Faculty of Technology

Water Resources and Environmental Engineering Research Group

Master’s thesis

Stable water isotopes as tracers on surface water

induced esker aquifer in northern Finland

Oulu 28.07.2014

Author:

Odediran Dare Peter

Supervisor:

Prof. Bjørn Kløve

University of Oulu

Advisor:

Jarkko Okkonen (Ph.D)

Geological Survey of Finland-GTK

Advisor:

Pekka Rossi (Ph.D)

University of Oulu

UNIVERSITY OF OULU Abstract of Thesis Faculty of Technology

Faculty of Technology Research Group

Environmental Engineering Water Resources and Environmental Engineering

Author Thesis supervisor Odediran, Dare Peter Kløve, B., Professor

Thesis title

Water isotopes as a tracer on surface water induced esker aquifer with groundwater abstraction in Northern

Finland

Major Subject Thesis type

Submission date Number of pages

Water Resources and

Environmental Engineering

Master’s Thesis July [2014] 79p+2 Appendices

Abstract

Abstract

Temporal and spatial variation in precipitation due to climatic effects has results into fluctuation in recharge

and runoff pattern which has a great effect on hydrological regimes of water dependent ecosystems. The

major concern is the influence of this variation on the interaction between groundwater and surface water

which plays a major role in groundwater resources availability and sustainability.

This study was carried out with the aim of identifying groundwater recharge sources and estimating the

evaporation relative to water input in the surface water bodies in Pudasjärvi area. These objectives were

achieved through the application of stable isotope and geochemical tracers. In addition, the fractionation

effect on the isotopic composition of precipitation, surface water, and groundwater samples were

considered in order to quantify the processes and reactions in the hydrogeological system.

The local meteoric water line and groundwater line established for Pudasjärvi were: δ2H = 7.26δ

18O + 3.29

and δ2H = 8.76δ

18O + 21.40 respectively. The signature of the precipitation that recharge the surface water

before evaporation effects occur are -14.920/00 and -106.47

0/00 for δ

18O and δ

2H respectively.

The amount of water loss due to evaporation was estimated using the evaporation to water ratio input

method. The result obtained shows that approximately 17 to 23% of the surface water bodies are been

evaporated, resulting into 77 to 83% of residual water fraction.

The interaction between groundwater pipes (24, PVP9 and PVP8) located along the Kivarijoki River flow

channel were examined, using both silica and stable isotopes as a tracer. The isotopes and geochemical

tracer analysis indicate that recharge of pipes 24 and PVP9 are predominately from surface water while pipe

PVP8 is mainly recharged by precipitation during summer period. On the other hand, the mixing ratio

results obtained through solute concentration analysis was very high compared to the results obtained

through stable isotopes during summer period. During winter period, both PVP8 and PVP9 are recharged

by winter/autumn rainfall and runoff. Therefore, proper measures should be taken to keep Kivarijoki

catchment in good conditions since there is surface water intrusion into the aquifer. However, δ18

O seems to

be more effective in quantifying mixing ratio in an aquifer because of it conservative nature compared to

geochemical tracer.

Library location

University of Oulu, Science and Technology library Tellus

Additional Information

FOREWORD

I acknowledge the Almighty God, my creator, the author and finisher of my faith, for

his love, grace and guidance granted unto me to the end of this Master’s degree

programme.

Sincere appreciation goes to Water Resources and Environmental Engineering

Reasearch Group and Maa-ja Vesitekniikan tuki (MVTT) for providing financial

support for this project.

My profound appreciation also goes to my ever attentive supervisor, Prof. Bjorn Klove

and my advisors, Jarkko Okkonen (Ph.D) and Pekka Rossi (Ph.D) for their support and

advice. I thank you all for the wealth of experience you had imparted onto me in the

past, during the course of this project and for those I am gaining at present and those I

am hoping to gain in the future. Sincere appreciation also goes to all my lecturers for

making my academic pursuit a reality.

My in debtness is also expressed to my parents (Elder and Deaconess J.T Odediran) for

their parental care, moral and financial support. Also to my siblings, (Abiodun, Bukola

Omolara and Kikelomo), my lovely angel (Halima) and the Folorunso’s family for their

support and encouragement.

I remain ever grateful to the people whose words and actions always leave me better

than they found me.

Special thanks to Mr Tuomo Reinikka, for his assistance during the field measurements.

At Oulu 30.07.2014

Odediran Dare Peter

TABLE OF CONTENTS

1 INTRODUCTION .............................................................................................................. 8

2 SITE CHARACTERIZATION ......................................................................................... 11

2.1 Geography and Climate.............................................................................................. 11

2.2 Geology and hydrogeology of the area ...................................................................... 13

3 GROUNDWATER ........................................................................................................... 16

3.1 Types of Aquifer ........................................................................................................ 18

3.2 Groundwater and its chemical components ............................................................... 19

3.3 Groundwater Recharge ............................................................................................... 22

3.3.1 Recharge tracer ................................................................................................. 23

3.4 Oxygen and Deuterium Analysis of water ................................................................. 25

3.4.1 Isotopic Fractionalization ................................................................................. 26

3.4.2 Types of Groundwater ...................................................................................... 29

3.5 Isotopic composition of Precipitation Recharging Aquifer ....................................... 31

3.5.1 Interaction of groundwater with surface water ................................................. 35

4 METHODOLOGY ............................................................................................................ 36

4.1 Data Collection ........................................................................................................... 36

4.2 Estimation of Local Evaporation Loss ....................................................................... 41

4.3 Mixing Analysis ......................................................................................................... 43

5 RESULTS AND DISCUSSION ....................................................................................... 45

5.1 Seasonal variation in oxygen and hydrogen isotopes in Pudasjärvi .......................... 45

5.2 Isotopic compositions of precipitation ....................................................................... 48

5.3 The isotopic composition of surface water ................................................................ 51

5.3.1 Average isotopic composition of precipitation for Pudasjärvi ......................... 53

5.3.2 Effect of evaporation on isotopic composition of surface water body ............. 54

5.4 Isotopic composition of groundwater......................................................................... 56

5.5 Interaction between surface water and groundwater in the aquifer ........................... 62

6 SUMMARY AND CONCLUSION .................................................................................. 67

7 REFERENCES .................................................................................................................. 70

APPENDICES:

Appendix 1: The results of isotopic analysis in (0/0)

Appendix 2: The results of solute concentration (SiO2) in mg/l

SYMBOLS AND ABBREVIATIONS

CO2 Carbon (IV) oxide

d Deuterium excess

D Deuterium (2H)

E Evaporation

EMMA End member mixing analysis

ET Evapotranspiration

EVWL Evaporation water line

FMWL Finnish meteoric water line

GMWL Global meteoric water line

GW Groundwater

h Relative humidity

I Water input

IAEA International atomic energy agency

k Hydraulic conductivity

K Degree in Kelvin

LEL Local evaporation line

LMWL Local meteoric water line

Number of rare isotope species

Nj Number of common isotope species

Pa Atmospheric pressure

PW Pore water pressure

R Isotope ratio

RMWL Rokua meteoric water line

RW River Water

SiO2 Silica or silicon dioxide

SMOW Standard mean ocean water

SW Surface water

T Temperature

VSMOW Vienna standard mean ocean water

ZPE Zero point energies

δA Isotopic signature of ambient air moisture

δE Isotopic composition of the evaporation moisture

εeq Equilibrium effect

∆ Separation

∆ε Kinetic fractionation factor 0/00 Per mil

α Fractionation factor

δ Delta-values

δ18

O Oxygen delta value

δ2H Hydrogen delta value

δL Isotopic signature of the surface water

δP Isotopic composition of precipitation

δMW Isotopic composition of mixed components

ε Enrichment factor 0C Degree in Celsius

8

1 INTRODUCTION

Groundwater is inevitable in order to meet water demand due to the scarcity of water as

a result of its uneven distribution across the globe. Groundwater accounts for more than

98% of the total amount of available freshwater etc (Hudak, 2005). Therefore, it is

considered as a vital feature of the natural environment, which serves as a medium for

environmental solutions and a key factor in understanding variety of geological

processes (Freeze et al., 1979).

The amount of water stored in the Finnish soil is more than the volume of water in

surface systems. This could complement the surface water during dry season or drought

period, but the alarming challenge is how to meet the future demand as human

population continues to increase and the climatic condition changes in order to avoid

over-abstraction of groundwater and squeezing ecological water consumption.

Previous studies have shown great concern on the sensitivity of catchments to climate

change (Siberstein et al., 2012; Pasini et al., 2012; Kløve et al., 2013; Kenneth et al.,

2014), but major challenge is how to predict and estimate these climatic effects on

subsurface waters as a result of time lag between incidence and effect (Rathore, 2005)

with some associated uncertainties (Thorpe, 2005) such as natural and anthropogenic

emissions due to human activities (Mort et al., 2001), land development activities which

involves covering of permeable soils with impervious surface whose adverse effect are

seen in groundwater recharge. The hydrological regimes of water- dependent

ecosystems have been affected (Barron et al., 2012) as a result of reduction in

precipitation and increase in evapotranspiration which potentially escalate groundwater

pumping rates and minimise its recharge (Treidel et al., 2012; cited in Kløve et al.,

2013). Therefore, pose a great risk to the effective management of groundwater

resources.

The temporal and spatial variation in the amount of water available on land surface due

to climatic changes can been seen in the fluctuation in recharge and runoff pattern

9

which have a great influence on the level of the groundwater, surface water and the way

they interact (Ficklin et al., 2010; Okkonen, 2011; Greg et al., 2012). Also, the

precipitation variation does affect the natural state of convective heat transfer as a result

of subsurface layer temperature been dispersed by conduction and groundwater recharge

(Luminda et al., 2012). This exchange of heat with the groundwater and ground surface

(Craig et al., 2009) is due to the direct contact between groundwater, ground surface and

unconfined aquifers (Okkonen, 2011).

Understanding groundwater recharge gives an insight to the source/ origin of the

groundwater. Different methods have been adopted in previous studies to measure

groundwater recharge and discharge such as analytical method (e.g.,Walton W.C, 1962;

Liang et al., 2012 ), groundwater flow models and flow net, water-budget methods (e.g.,

Nimmo et al., 2005; Lee et al., 2006), thermal methods (e.g., Becker et al., 2004; Blasch

et al., 2007; Christain et al., 2011; Epting et al., 2013), chemical and isotopic methods

which involves the use of chloride-mass balance methods, stable isotopes etc. (e.g.,

Kendall et al., 1998; Oxtobee et al., 2002; Kortelainen, 2007), and geological and

hydrological consideration.

Over the past decades, environmental isotopes have been a useful tool that gives

introspection into hydrological processes which involves evaporation effects on both

surface and sub-surface bodies (Kendall et al., 1998; Geyh 2000). Kendall et al. (1998)

were bordered on why these environmental isotopes were under-utilised even with the

fact that hydrological connection for precipitation with unusual isotopic composition

along a flow path can be established despite any contrast from hydraulic measurement

or model.

This project will give an insight on how the application of stable isotopes oxygen (18

O

/16

O), hydrogen (D/ H) can be used to explain hydrogeological processes of the area

under studies. Previous studies carried out in this area by Okkonen (2011) focused on

groundwater and surface water interaction by analysing Ca2+

, Cl-, NO3-N and SiO2

concentration and electrical conductivity.

10

The aims of this project are to:

i) identify groundwater recharge sources in Pudasjärvi area through isotopic

measurement

ii) identify the interaction between the surface and sub-surface water in the area

iii) estimate the evaporation rate on surface water bodies

11

2 SITE CHARACTERIZATION

Having depth knowledge on the climatic condition of catchment area and

hydrogeological aspects of an aquifer is very important to carry out a successful study

on groundwater.

2.1 Geography and Climate

The site (Pudasjärvi) considered in the study is located in the northern part of Finland

area and belongs to the middle-boreal zone. The Pudasjärvi aquifer (Figure 1) has a

surface area of 4.5km2 and constitute an integral part of the 10000km

2 river

Ijoki

catchment encircled by Lake Pudasjärvi with catchment area of 8424 km2 and both

Lake Kivarijärvi and river Kivarijoki is 316 km2

(Okkonen, 2011)

During the study periods in Pudasjärvi, mean annual air temperature was 30C and

precipitation usually varies between 600mm to 650mm (OIVA, 2014). Several

predictions have shown that an increase between 2-60C in the mean annual air

temperature and about 7–26% increase in mean annual precipitation will occur due to

influence of climate change, this changes will enhance an increase in groundwater

recharge and its impact will be felt mostly in the northern region during winter period

than the southern part and summer period (e.g Gong et al., 2012, Jylhä et al., 2009) with

reduction in unsaturated zone (Negrel and Petelet-Giraud 2011).

12

Figure 1: (a) The river iijoki watershed and its location in Finland (b) view of the

Pudasjärvi aquifer and sub-basins 1-3 with the red arrows indicating the flow directions.

(Okkonen and Klove, 2011)

The groundwater quality in Pudasjärvi aquifers are exposed to a lot of risks as a result of

human impacts on the environment due to activities such as farming, abattoir location in

the area, airport and de-icing salt used to prevent ice on the road networks in the area

13

(Okkonen 2011: 25). The area is also partially covered with gravel pit. Therefore proper

management policies need to be carried out in such area in order to improve the quality

of groundwater in Pudasjärvi.

2.2 Geology and hydrogeology of the area

The Pudasjärvi area belongs to the Archean basement region (Figure 2) which constitute

of ancient rocks that serves as the beginning of a new era for the second stage in the

development of Finnish bedrock from age 3200-2700 Ma (Nenonen and Portaankorva

2009). The landscape of the area is characterised by different shapes of small hills,

valleys, depressions and small plains with a combination of forest, lakes and mires, ca.

70km northeast of Oulu (Nenonen and Portaankorva 2009).

The Pudasjärvi aquifer is a part of an esker deposited between two ice lobes during the

ice treat age (PSV-Maaja Vesi 2001). According to definition in the Encyclopaedia

Britannica an esker “is a long, narrow, winding ridge composed of stratified sand and

gravel deposited by a sub-glacial or en-glacial melt water stream”. Eskers do have a

unique landscape and are mostly unconfined aquifers through which groundwater seeps

to other features close to it such as lakes, springs, rivers and marshy lowland (Rossi et

al., 2012).

Based on the Archean bedrock formation in the area of study, there is an accumulation

of clay, sand, gravel and glacial till (Lehtinen et al., 2005) According to (Okkonen

2011), the sand size varies and its layer thickness ranges from 1 to 20m with the

bedrock and ground surface between 94 to 96m and 110 to 135m above sea level

respectively.

14

Figure 2: General geology of Finland showing Archean Pudasjärvi complex (modified

from Huhma et al. 2011)

15

There are varieties of groundwater deposits in Pudajärvi region which includes eskers,

ice-marginal formations, basal tills etc. with different rock types. Rocks in the area are

mainly gneisses with greenstone periods and igneous rocks which represent bimodal

(basaltic/felsic) magnetism and its interaction with loose surficial deposit present in the

area determines its topography while some of the rocks are also seen as mica schist’s

containing either pyroxene or cordierite.

Till materials from the ice degalciation can gather together to form hummocky moraines

with different sizes and shapes. According to Tikkanen (2002), the till covers upto 1,600

Square kilometres of the areas in northern Finland. The formations of these hummocky

moraines are due to the independent accumulation of thick layers on basal till and the

lithological composition of the uppermost till gives a reflection of features of the local

bedrock while the till geochemistry reveals metal anomalies in the area under study

(Sarala and Rossi 2006).

16

3 GROUNDWATER

Understanding groundwater formations requires having a vital knowledge of the

geological environments of its occurrence, physical laws involves in its flow and its

chemical evolution. Also, understanding the influence of hydrological cycle is of a great

importance.

Groundwater is defined as “subsurface water that occurs beneath the water table in soils

and geological formations that are fully saturated” (Freeze and Cherry, 1979) and can be

observed only at recurrent points such as springs and boreholes. According to U.S

Geological Survey, the total water supply across the globe is approximately 1,386

million cubic kilometres of water with 90 percent of it salty while 68 percent of the total

fresh water is in ice and glacier and 30% of the fresh water is stored in ground.

Nevertheless, 1/150th

of one percent (0.007 percent) of total water is attributed to fresh

surface water sources (Figure 3).

Figure 3: World fresh water resources (modified from USGS 2014)

17

Groundwater resides in openings within rocks and dispersed rock particles (Hudak

2005). Although it is less vulnerable to contaminants compared to surface water due to

the filtration process that occurs through the vadose zone of the soil, but it’s prone to

depletion due to the pressure mounted on it as a result of uneven distribution of water

across the globe. However, it can be found in two major zones (Figure 4) namely:

i) Unsaturated Zone: It’s the subsurface sediment above the water table

containing air and water and quantity of water in this zone varies widely

with high sensitivity to climatic factors (Chapelle, 2001) but the water can’t

be pumped by pipe as a result of capillary forces holding it together. Note

that this zone can also be divided into three sub-zones such as the root zone

(soil water zone), the capillary zone or fringe zone and the vadose zone or

intermediate zone.

ii) Saturated Zone: This is the area beneath the water table where all pores are

completely filled with water. The water table separates the aeration zone

from saturation zone and its elevation can be obtained when the pore water

pressure PW is equal to atmospheric pressure Pa but fluctuate in response to

seasonal climatic variations and recharge from individual storms events. The

pore water pressure (PW) is defined as the stress carried by the pore water

while atmospheric pressure (Pa) is known as pressure exerted by the earth’s

atmosphere at a given point.

18

Figure 4: Groundwater Zone (from U.S. Geological Survey 2012)

3.1 Types of Aquifer

According to Hudak P.F. (2005) an aquifer “is a body of saturated rock or sediment

capable of transmitting useful qualities of water to pipes or springs”. However, the

materials composition determines the amount and quality of groundwater. For example,

large particles enhance fast flowing water as a result of openings in soil, typically in a

river channel, and where the spaces are small or area with small particles the flow rate is

slower which is often less than 10 m/a such as water inundating a flood plain (Hudak

2005: 25). These qualities could be associated with the size, the number of voids and the

degree of interconnection between the pores and fissures (Mazor 2004: 16).

Aquifers are made of unconsolidated sand, gravel, fractured rocks, sandstone etc and

serve as a means through which groundwater can be recovered. Its ability to store,

transmit and produce groundwater is attributed to variety of factors, which are:

permeability, hydraulic conductivity (k) etc. The permeability is the ability of soil to

19

allow water to penetrate theough its pores or voids while the hydraulic conductivity is

the measure of soil permeability.

Aquifer can be classified as:

i) Confined aquifer: it’s an aquifer bounded by a low-permeability bed (usually

consist of either clays,shales or dense rock) and is a complete saturated

aquifer. The removal or pumping out of water in this type of aquifer leads

sto decrease in porosity as the granualr skeleton contracts which alter result

in an increase in water volume. Note: the pressure of water in confined

aquifer is greated than the atmospheric pressure, which is the main reason

why the water rises to a level higher than the aquifer when it is been

penetrated with pipe while the flow of groundwater in it is determined by the

water head gradient and the degree to which the system is drained (Mazor

2004: 27)

ii) Unconfined aquifer: in this aquifer the water table is exposed to the

atmosphere through permeable materials i.e it has no confining alyer above

it. Examples include areas of coastal sands and alluvial deposits in river

valley.

3.2 Groundwater and its chemical components

Having depth knowledge of groundwater chemistry gives more insight on groundwater

flow processes, its interaction with the environment, bio-geochemical reactions of water

with soil and rock material.

Groundwater is an inevitable component of the hydrologic cycle (Figure 5) because it is

renewable in nature. Its replenishment comes from precipitation, surface water and

human activity related to water such as irrigation water in a basin.

20

Figure 5: Hydrological Cycle (Modified from eoearth.org).

Water contains two hydrogen atoms with one oxygen atom which are bonded together

un-symmetrically, the ions formed is as result of water dissolution as presented in

equation (i)

H2O H+ + OH

- (1)

Where the positive and negative signs indicate the charge on the ions.

The composition of groundwater is influenced through penetration of rainwater and

surface water, which are slightly acidic in nature. The acidic nature of rainwater and

surface water are due to small concentration of atmospheric constituents, dissolved

21

gases and salts derived from ocean aerosols such as chloride and sodium. When soil

interacts with dissolves minerals, different composition of groundwater is formed

depending on its residence time, temperature and oxidation-reduction reaction which are

influenced by chemical reaction. Most of the constituents (Table 1) are in ionic form.

Therefore, groundwater can be seen as an electrolyte solution (Freeze and Cherry, 1979:

84). The reasons for the dissolved gases are described by Freeze and Cherry (1979):

1. Exposure to the earth’s atmosphere prior to infiltration into the subsurface

environment

2. Contact with gases during infiltration through the unsaturated zone

3. Gas production below the water table by chemical or biochemical reactions

involving groundwater, minerals, organic matter, and bacterial activity.

Table 1: Classification of Dissolved Inorganic Constituents in

Groundwater (Modified from Freeze and Cherry, 1979: 85)

Major constituents (greater than 5 mg/l)

Bicarbonate Silicon

Calcium Sodium

Chloride Sulfate

Magnesium Carbonic acid

Minor constituents (0.01-10.0 mg/l)

Boron Nitrate

Carbonate Potassium

Fluoride Strontium

Iron Major constituents (less than 0.1 mg/l)

Aluminum Molybdenum

Antimony Nickel

Arsenic Niobium

Barium Phosphate

Beryllium Paltinium

Bismuth Radium

Bromide Rubidium

Cadmium Ruthenium

Cerium Scandium

Cesium Selenium

22

The reaction of groundwater with CO2 which is the most important dissolved gases is

shown in equation (2) and (3), the concentration of CO2 in the soil is 50 to 100 times

higher compared to its concentration in the atmosphere which is 0.03% by volume

(Mazor, 2004: 136).

CO2 (g) + H2O CO2 (aq) + H2O (2)

CO2 (g) + H2O H2CO3 (aq) (3)

In Finland, the groundwater is liable to be influenced by acidification due to the low

natural buffering capacity of the mineral soil, low calcium content in the precambrian

bedrock including areas covered with acidic rocks (Soveri, 1985) and in some places

where the unsaturated zone is shallow, the time of infiltration water with the soil will be

short. In this case, the isotopic composition of the groundwater might be enriched.

3.3 Groundwater Recharge

Recharge is seepage of water into groundwater system. The replenishment of the

groundwater system might be through rainfall which could also come in form of snow

and surface water (rivers and lakes). This recharge occurs rapidly or slowly through

Chromium Silver

Cobalt Thallium

Copper Thorium

Gallium Tin

Germanium Titanium

Gold Tungsten

Indium Uranium

Iodide Vanadium

Alnthanum Ytterbium

Lead Yttrium

Lithium Zinc Manganese Zirconium

23

fissures or by infiltration through permeable soil and rock formations during and after

period of rain and snow-melt. Groundwater recharge is regulated by different factors

such as: the amount of precipitation, evaporation, transpiration and infiltration rate

which depends on the soil texture, ambient moisture content, runoff and its compaction

degree. For example, high intensity of precipitation on soil such as clay will lead to an

increase in overland flow with a less recharge in such area due to low permeability of

clay soil and during this period less water is lost as evapotranspiration. In temperate

region, less than 5 to 25% of precipitation penetrates to the water table (Clark and Fritz,

1997: 80). Gong et al (2012) noted that the evapotranspiration rate differs in each soil

types. For example, peatland evapotranspiration (ET) is strongly influenced by surface

energy partitioning and its resistance features.

However, recharge to a lake or a river can be as a result of leakage through its beds.

This interaction result to a change in the quality of the groundwater. The mixture

composition can be identified with the use of stable isotope and other environmental

tracers.

3.3.1 Recharge tracer

Identifying groundwater recharge plays a major role in groundwater resources

availability and sustainability. As a result of this, different techniques and methods have

been adopted to estimate recharge rate, discharge rate and their sources. Some of the

methods are: stable isotopes, chloride mass-balance method, groundwater dating using

carbon-14, radiocarbon data (tritium), water table fluctuation analysis, solute

concentrations, CFC-concentrations and artificial tracer (deuterated water). (Crandall et

al., 1999; Becker and Coplen 2001; Okkonen 2011; Gao et al., 2010; Ordens et al.,

2012).

Nevertheless, water isotopes and a solute concentration of silica (SiO2) method were

adopted in this study. Water isotopes are presented in next sub heading (chapter 3.4).

Silica, a geochemical tracer was used by Okkonen (2011) to examine the interaction

24

between groundwater and surface water in Pudasjärvi region and it is of great interest to

validate the result obtained by comparing it with the result from stable isotope analysis.

Silica or silicon dioxide (SiO2) is the most abundant mineral in the Earth’s crust and

rarely occurs in elemental form. They are mostly in alpha-quartz form which is a major

component of igneous rock such as granite and pegmatites (Gbadebo et al 2013). The

chemical weathering of silicate in rocks results into dissolved silicate in natural water

and it solubility can be characterized by the following equilibria (Freeze and Cherry

1979: 269):

SiO2 (quartz) + 2H2O Si(OH)4 (3)

Si(OH)4 + (4)

=

+ (5)

4Si(OH)4 = + + O (6)

The concentration of SiO2 varies in most groundwater with a typical range from 10 to

30 mg/l while it content in rain water is less than 1mg/l (Freeze and Cherry 1979) and

silicate content in the snow sample in this study is less than 0.1 mg/l. The silicon

concentration of groundwater increases compared to surface water due to long residence

times of groundwater in the aquifer and contact time of water with soils and rocks

during seepage. It is therefore obvious that an increase in silicate content of surface

water is as a result of groundwater input into the system and vice versa. Therefore, the

rainfall, surface water, groundwater flow path and residence time can be distinguished

by using this geochemical tracer based on its concentration.

25

3.4 Oxygen and Deuterium Analysis of water

The transition phase of water between ice, liquid and vapour with the properties of the

isotopic molecules of water throughout the hydrological cycle were noted in order to

carry out a successful research.

Isotopes are either stable or unstable. The unstable isotopes are radioactive in nature and

changes into different element while stable ones behave almost identical in chemical

reaction. An oxygen and hydrogen isotope falls into the stable isotopes categories.

Oxygen has three major isotopes namely: 16

O which is the most abundant oxygen

isotope (99.726%) and two heavy isotopes in form of 18

O and 17

O whose average

abundance are 0.200% and 0.0379% respectively while the hydrogen isotopes has

both1H and

2H (Deutrium) with mass abundance of 99.985% and 0.015% respectively

(Gat 2010: 9).

The combination of oxygen and hydrogen gives an isotopic composition of water with

the water cycle. The water molecules are classified into light molecules (1H2

16O) and

heavy water molecules (1HD

16O and

1H2

18O) (Mazor 2004; 181). The conservative

nature of stable isotopes of oxygen (18

O) and hydrogen (2H) makes it more reliable and

an important water tracer. This means stable isotopes do not undergo chemical changes

along flow path and makes it a better tracer to characterise recharge source

The isotopic systems are usually reported in isotope ratio R (Gat 2010: 10)

R =

⁄ (7)

Where is the number of rare isotope species

is the number of common isotope species

26

However, it’s better to directly report the measured difference in the isotope

composition of the sample (x) and an accepted standard (std) in terms of dimensionless

δ-values (also known as “delta-values”) as shown in equation (8) because the

abundances of the heavy isotopes are very low in many cases Criss (1999: 31).

=

× 1000 (8)

Since the composition are expressed in terms of isotopic composition of ocean water.

The accepted standard (std) as agreed upon by international bodies is called Standard

Mean Ocean Water (SMOW) (Craig 1961). Therefore equation (8) above can be

expressed as shown below for the isotopic composition of water.

δD0/00 =

× 1000 (9)

δ18

O 0/00 =

× 1000 (10)

Nowadays, VSMOW (Vienna Standard Mean Ocean Water) is the established standard

used since the period the standard composition has been deposited at the International

Atomic Energy Agency (IAEA) in Vienna (Gat 2010: 17). The delta value (δ) is

expressed in per mil 0/00 deviation from the SMOW standard. A positive delta value

indicates an enriched isotope while a negative value denoted a depleted isotope.

3.4.1 Isotopic Fractionalization

Isotopes fractionation is one of the major factors and tool considered in order to justify

the result of the isotopic composition of the samples and quantifies the processes in the

hydrogeological system.

Fractionation is the change in the relative proportion of one isotope to another in

chemical or physical process. Isotopes fractionation is caused as a result of both kinetic

and equilibrium effect. However, it involves the partitioning of a sample into two or

27

more parts that have different ratios of heavy (enriched) and light (depleted) isotopes

than the original ratio (Criss 1999: 18). Isotopic equilibrium considered in this study

involves the fractionation between water and vapour that plays a major role in

partitioning of 18

O and 2H (deuterium). The fractionation factor (α) between substance

X and Y is denoted as:

= RX/RY (11)

Where R is the atomic ratio of N*/N of a heavy (N*) to a light (N) isotopes and it

represents both 18

O/16

O and 2H/

1H in the context of this study.

Isotopic exchange is influenced by other parameters such as enrichment factor ( ) and

separation ( ) Clark et al (1999). The relationship between these parameters can be

expressed as shown below:

= - (12)

However, the fractionation factor (α) needs to be expressed in per mil (0/00). Therefore

equation (11) becomes:

=

=

(13)

While the enrichment factor ( is also used to express the isotopic difference in 0/00

notation:

= (

) ×10

3 = (α-1) ×10

3 (14)

Molecules with heavy isotopes have a higher dissociation and binding energy compared

to molecules of lighter isotopes. This is attributed to the difference in their Zero point

energies (ZPE) (Criss 1999: 59). According to Clark et al (1997: 22), Zero point energy

“is the minimum potential energy of a molecular bond in a vibrating atom.

28

The composition of precipitation depends mainly on temperature at which the oceanic

water is evaporated and the condensation temperature at which clouds and rain or snow

are formed. This means that temperature has a major influence on the isotopic

composition of precipitation, surface water and sub-surface water. The degree of

evaporation on the isotope composition of precipitation is highly influenced by

temperature and other factors such as humidity, aerial coverage due to vegetation etc.

There is distinct difference between the evaporation of water within the soil column and

surface water as a result of restriction in the mixing within the liquid and gas phase due

to the texture of soil matrix (Gat 2010). Due to a decrease in temperature, the

precipitation process is affected resulting into an increase in the depleted value of δ18

O

and δ2H. It shows that strong relationship exists between temperature and isotopes of

precipitation which helps to develop an insight into groundwater recharge and its rate of

circulation.

Hydrogen isotopic variations are often generated in phase transition of water between

vapor, liquid and water. Clark and Fritz (1997) examined the results of fractionation

factors for δ18

O in water-vapor exchange at different temperature conducted by different

researchers and discovered that fractionation is temperature dependent as fractionation

factors decreases with an increases in temperature.

As a result of fractionation, vapor is enriched in light water molecules with a relative

negative δD and δ18

O values. There is a high correlation in the way both hydrogen (2H)

and oxygen (18

O) is fractionated but a little different in their magnitude. The

fractionation factor (α) is 1.0094 and 1.079 at room temperature for oxygen and

hydrogen respectively (Criss 1999: 19). This relationship is established as Global

Meteoric Water Line (GMWL) (Craig 1961) and it presented as:

δ2H = 8δ

18O + 10 (15)

Where +10 intercept is known as “deuterium excess”.

29

The deuterium excess (d) is a great tool to determine the source of water vapor and

contribution of recycled moisture to precipitation (Vandenschrick et al 2002: 48;

Andreo et al 2004: 562; Windhorst et al 2013) with little insignificant variation in the

alter history of cloud mass. It is acquired during evaporation. According to the Andreo

et al (2004), the deuterium excess (d) values of precipitation close to 10 are e.g.

characterized as water from Atlantic Ocean and values close to 22 are attributed to East-

Mediterranean while the intermediate valves closer to 14 are considered to be from

Western Mediterranean basin. The d values become higher as a result of high

evaporation rate attributed to high temperature and low relative humidity during the

formation of water vapor associated with kinetic isotopic effect.

3.4.2 Types of Groundwater

Ground waters are classified based on the kind of rock formation within the geological

area where the water resides. According to Hudak (2005), the classifications are thus; (i)

Connate water; (ii) Magmatic water; (iii) Metamorphic water; (iv) Meteoric water.

Meanwhile, the isotopic composition of the water differs as shown in Figure 6(a) and

Figure 6(b).

Connate water is formed as a result of entrapped water in marine sediments during the

deposition period and does not have a contact with the atmosphere for a significant part

of a geological time interval (Bowen R., 1986). The concentration of mineral contents is

very high in connate water because of its contact with sediments. Magmatic water is

also called Juvenile water. It originates from magma through volcanic eruption while

metamorphic water is formed due to minerals reaction which involves ions exchange

during metamorphism. However, its contribution to the groundwater is uncertain but

extremely low compared to recharge through infiltration (Holting 1980).

Meteoric water is derived from Earth’s atmosphere and has its formation in the ground

through rainfall or seepage from surface water bodies. Groundwater from meteoric

origin has a high depleted isotopic composition compared to groundwater from other

sources. Knowing the meteoric water input into the system is very vital because it

30

serves as a baseline for groundwater. Thus, the Local Meteoric Water Line (LMWL)

must be established. The δ18

O and δ2H

0/00 VSMOW both represent the composition of

heavy stable isotopes in per mil according to Vienna Standard Mean Ocean Water.

Figure 6a: Ranges of δ18

O in rocks and water types (Modified from Clark and Fritz,

1997)

31

Figure 6b: Ranges of δ2H in rocks and water types (Modified from Clark and Fritz,

1997)

3.5 Isotopic composition of Precipitation Recharging Aquifer

There is spatial variation in the isotopic composition of precipitation across the Earth’s

surface (Figure 7) due to atmospheric effect such as evaporation, recycling by

ecosystems and condensation temperature which enhance a decrease in the heavy

isotope content of precipitation (Dansgaard 1964, Bowen and Revenaugh 2003)

32

Figure 7: The global maps of δ18

O and δ2H in precipitation across the globe (Modified

from Darling et al., 2003).

During the infiltration process through the unsaturated zone, the variation of δ18

O and

δ2H in precipitation are disentangled or lost (Figure 8) (Clark and Fritz 1997). It means

there is deviation in the isotopic composition of groundwater from the precipitation

values. This deviation can be attributed to the vegetation types, soil types,

evapotranspiration, runoff, and seasonal variation in recharge, climatic change, length of

33

flow path and residence time (Clark and Fritz 1997; Lerman et al 1995). Studies have

shown that isotope ratios in shallow groundwater represent the mean annual

precipitation (Clark and Fritz 1997; Criss 1999). For example, Kortelainen (2007)

reported that, there were no significant differences between the isotopic ratio of

precipitation and groundwater in Finland which denote that the isotopic composition of

precipitation and temperature are conserved in groundwater.

In some cases, there might be a significant difference in groundwater isotopic signal

from the precipitation due to seasonal biases to recharge. In temperate region, recharge

during summer is low and the isotopic composition of groundwater is enriched in heavy

isotope ratio while the highest recharge occurs during runoff (snowmelt) with

composition isotopically depleted.

Figure 8: Schematic of the attenuation of seasonal isotope variations (δ18

O and δ2H) in

recharge waters during infiltration through the unsaturated zone and movements within

the saturated zone (Modified from Clark and Fritz 1997: 82)

In Finland, the seasonal variations in isotopic composition of groundwater (Figure 9)

are even in the southern part, higher in the northerner and eastern part of the country.

34

There is an indication of snowmelt water input in early summer due to signal of lighter

isotopes in the groundwater system (Kortelainen and Karhu, 2004).

Figure 9: The distribution of δ18

O in groundwater from dug pipes, springs and drilled

bedrock pipes in Finland (modified from Kortelainen and Karhu 2004).

35

3.5.1 Interaction of groundwater with surface water

The interaction between lakes and groundwater occurs basically in two ways:

groundwater flows through the streambed into the lakes, the lake water seeps through

the sediments into groundwater and both ways are regarded as gaining body and losing

body respectively. The direction of exchange flow within the systems can be determined

through hydraulic head which is controlled by the positions of water bodies with

reference to groundwater flow systems, geological attributes of the beds, and their

climatic settings (Winter 1999).

Surface water is subjected to evaporation and its isotopic composition clusters along the

Local Evaporation Line (LEL). The Local Evaporation Line (Figure 10) is the line that

shows the influence of local conditions such as the temperature, humidity and wind over

the evaporation period (Gibson et al., 1993)

Figure 10: Generalized δ18

O and δ2H plot showing the Meteoric water line and the

Local evaporation Line (Modified from Gibson et al., 1993)

36

4 METHODOLOGY

Precipitation, subsurface water and surface water samples were collected from

Pudasjärvi study site and analzyed for Oxygen (18

O/16

O or δ18

O) and deuterium (2H/

1H

or δD). The water samples were carried out in two contrasting seasons mainly: the

summer and winter period in order to distinguish the isotopic composition of subsurface

water input to the lake or vice versa. The isotopic ratios of these samples were evaluated

to ascertain the main source of recharge to the groundwater points. Also, comparison

was carried out about the effectiveness of silica (SiO2) tracer that was previously used

by Okkonen (2011) in Pudasjärvi. The isotopic compositions of data collected between

18.5.2006 to 31.5.2007 were used for the result calculations while the isotopic

compositions of year 2013 samples were used to ascertain the correctness of earlier

measurements. The winter period compositions are calculated based on period from

5.7.2006 to 4.3.2007 while 18.5.2006 to 9.8.2006 and 3.4.2007 to 31.5.2007 were

considered as the summer period.

4.1 Data Collection

The groundwater and surface water sampling points are located in Pudasjärvi, in North

Ostrobothnia (Altitude 65.4o, Longitude 26.96

o) as shown in (Figure 11). The sampling

period was between year 2006 to year 2007 by Okkonen (2011) and later in 2013. The

precipitation samples were taken from Nuoritta, 40 km South-East from Pudajärvi in

2013. The collector for the precipitation samples had little paraffin oil in order to

prevent evaporation and the samples were later stored in a 100 ml clean bottle. The

groundwater sampling follows the sequence shown in (Figure 13) below. The

groundwater level was noted in the pipe with the use of sampler attached to the end of a

measurement tape which makes a dangling sound when it hits the water table level. In

addition, the groundwater was purged out (Figure 12) with a submersible pump for 20-

25 minutes in order to remove stagnant water and ensure that the subsurface water

characteristics are been reflected. This was done by measuring the field parameter such

as the PH, electric conductivity and the temperature of the samples. The needed samples

37

were collected with the bottles filled with no air space in order to prevent gas exchange

within the samples and the bottles were tightly closed, labelled, wrapped with parafilm

and stored in a dark container to prevent it from kinetic fractionalization through

evaporation because the evaporation during storage and transportation of the samples

from field to the laboratory will alter the isotopic enrichments of 2H and

18O of the

samples.

Figure 11: Map showing sampling points. (Background map from National Land

Survey of Finland and modifications by Odediran Dare).

38

Figure 12: Pumping of the groundwater samples through a submersible pump (photo by

Odediran Dare).

39

Figure 13: Steps in groundwater sampling (modified after Sunsaram et al; 2009: 10)

40

The isotopic composition of the water samples was carried out through Picarro L2120-I

analyzer (Figure 14) in the Water and Environmental Laboratory at the University of

Oulu, Finland through a wavelength-scanned cavity ring-down spectroscopy (WS-

CRDS). This analyzer is based on absorption measurement technique; the absorption of

laser beam in the optical cell is measured by using the changes in the frequency of the

beam to form absorption spectrum in the samples through which the isotopic

composition can be determined. Each beam has ions that have common features such as

momentum that differs from the character of the ions in another beam through which the

mass spectrum of individual beams are counted and compared electronically with the

results given in relative abundances.

Figure 14: Picarro L2120-i analyser (Isokangas 2012, 38 )

41

Each sample were filled into a 2ml glass vials with caps and loaded into the machine

autosampler and precipitation samples, few groundwater and surface water samples

were filtered with syringe filter before filled into the vials as a result of mineral oil

added to prevent evaporation in the precipitation samples and particulate matter in both

surface and subsurface water. The analysis is done six times per sample in order to

enhance measurement accuracy and eliminate memory effects. During the analysis

process, three sets of standards samples (Table. 2) namely: Hawaii-water, Oulu tap

water and Snow are introduced into the data at the beginning, middle and end of each

analysis in order to calibrate the results and assure accuracy with precision.

Table 2: Isotopic composition of the standards

Average Standard Average Standard

Calibrated δ18O deviation δ18O Calibrated δ2H deviation δ2H

Hawaii 0 0.15 2.1 0.7

Hanavesi (Tap water) -10.33 0.12 -78 0.24

Lumi (snow) -18.82 0.07 -138.8 0.17

4.2 Estimation of Local Evaporation Loss

The evaporation effect on the surface water bodies was estimated by adopting Craig and

Gordon (1965) method. Factors taken into consideration are relative humidity, isotopic

composition of ambient vapour and temperature (K).

The net enrichment factor ( that exist between the surface water and open atmosphere

is the sum of kinetic isotope fractionation and equilibrium effect ( ). The kinetic

fractionation factor ( ) proposed by Gonfiantini (1986) for 18

O and 2H respectively are

of these form:

O = 14.2 (1-h) 0

/00 (16)

H = 12.5 (1-h) 0

/00 (17)

42

Where, the relative humidity (h) is to be determined.

The equation of the net enrichment factor is shown below:

= + (18)

The equilibrium effect was calculated by considering the fractionation between vapour

and water for both 18

O and 2H with respect to temperature (Criss, 1999)

= 1000(1- ) (19)

Where 18

O = −2.0667−0.4156 (103/T) +1.137(10

6/T

2) (20)

2H = 52.612−76.248 (10

3/T) +24.844(10

6/T

2) (21)

As proposed by Craig and Gordon (1965), the isotopic composition of the evaporation

moisture ( ) is determined and the result presented in the per mil notation:

= (δL –hδA- ) / (1-h + ) (22)

Where δL is the isotopic signature of the surface water; h is the relative humidity; δA is

the isotopic signature of ambient air moisture; is the the net enrichment factor. The δA

is calculated based on the assumption that the precipitating vapour is in equilibrium with

the isotopic composition of precipitation (δP) (Peng et al., 2012) and it is represented

below as:

= δP - (23)

However, the evaporation (E) relative to water input (I) in the surface water bodies can

be estimated by considering that the isotopic composition of the surface water at time (t)

is at steady state and pipe the surface water is pipe mixed (Gibson and Edwards 1996;

Ferguson et al., 2007; Wassenaar et al., 2011) and is expressed with respect to δ18

O as:

43

= (δ

18OL - δ

18OI) ((1-h + 18

O) / (δ18

OL + 1) ( 18O +

⁄ )

+ h (δ18

OA - δ18

OL) (24)

Where, δI is the isotopic signature of the precipitation and α is the isotope fractionation

factor ( ).

4.3 Mixing Analysis

In order to estimate the water source mixing proportion in the observation pipes

examined during this work as a result of discharge from surface water and runoff from

precipitation, an effective analytical tool called end member mixing analysis (EMMA)

was adopted. This was achieved by quantifying the principal components that

constituted to the groundwater with the use of appropriate tracers (stable isotopes and

geochemical tracer-SiO2).

In brief, Leibundgut et al (2009) described EMMA as the measurement of water

chemistry and isotopes based on some assumptions about the mixture. Those

assumptions are as follows (Barthold et al., 2011):

1. The groundwater is a complete mixture of source substance with fixed

composition

2. The mixing should be based on hydrodynamic process

3. The tracers substances must be conservative

4. The solutions from the origin/source have extreme concentrations.

According to Peng et al. (2012), the calculation of the two-end member isotopic mixture

can be carried out using equations below based on the proportions of W1 and W2 in the

mixed water.

= × + × (25)

44

= 1- (26)

To get , equation (26) is substituted into equation (25) and then rearranged.

Therefore:

=

(27)

Where and represent the fractions of W1 and W2 in the mixed water

represents mixture components

However, mixing relationship might not show the exact point where the mixing occurs

within the aquifer or the pipe observed. Stable isotopes preserve the mixing ratio due to

their conservative nature while the solutes changes due to geochemical reaction (Clark

and Fritz, 1999: 105)

45

5 RESULTS AND DISCUSSION

5.1 Seasonal variation in oxygen and hydrogen isotopes in Pudasjärvi

The trend of the isotopic composition of samples used is presented in box plot (Figure

15). It is obvious that the isotopic compositions of surface waters are enriched, and

groundwater is depleted with heavier isotopes.

Figure 15: Isotopic trends for surface waters and groundwater in Pudasjärvi region

The results were later classified into two major seasons (summer and winter) samples as

showed in Figure (16) and (17) respectively. The mean values of the surface water and

groundwater samples from May 2006 to May 2007 and the precipitation samples from

May 2013 to October 2013 are shown in Table (1).

46

Table 3: Stable isotopic composition of precipitation, groundwater and

surface water with respective to summer and winter seasons.

Water Type

Summer Winter

δ18O (0/00) δ2H (

0/00) δ18O (

0/00) δ2H (

0/00)

Precipitation -9.89 -68.12 -10.27 -71.56

Surface Water

KJ -11.37 -84.64 -13.19 -95.51

PJ -12.15 -86.77 -13.17 -95.42

Groundwater

AK -13.12 -96.63 -13.79 -99.37

OY2 -13.75 -99.89 -14.49 -104.87

POR2 -13.34 -96.46 -13.71 -98.85

PVP9 -12.72 -91.29 -13.36 -94.57

PVP8 -12.99 -92.76 -13.63 -96.97

TK -13.60 -97.65 -14.08 -100.88

VVO -13.44 -97.30 -13.99 -100.92

24 -12.77 -90.78 -12.91 -91.70

During the summer period, the δ18

O values of Kivarijoki River are between -10.310/00 to

-12.450/00, Pudasjärvi Lake are between -10.88

0/00 to -12.99

0/00 while the δ

2H values for

both Kivarijoki River and Pudasjarvi Lake is (-80.230/00 to -89.13

0/00) and (-80.61

0/00 to

-94.730/00) respectively. The variation in the groundwater samples during the summer

period ranged from (-12.100/00 to -13.97

0/00) and (-86.34

0/00 to -101.45

0/00) in both δ

18O

and δ2H values respectively.

During the winter period, the isotopic composition of the samples are depleted in both

δ18

O and δ2H values. The δ

18O values of Kivarijoki River is between -11.29

0/00 to -

14.750/00, Pudasjärvi Lake is between -12.31

0/00 to -13.75

0/00 while the δ

2H values for

both Kivarijoki River and Pudasjarvi Lake is (-81.880/00 to -104.88

0/00) and (-89.61

0/00 to

-97.280/00) respectively. The variation in the groundwater samples during the winter

47

period ranged from (-12.310/00 to -15.40

0/00) and (-87.10

0/00 to -110.19

0/00) in both δ

18O

and δ2H values respectively. It was noticed that, the isotopic composition of

groundwater pipe (24) is more enriched in both δ18

O and δ2H compared to other

groundwater samples even during both summer and winter period. This is associated to

the equilibrium effect suggested by Craig and Gordon (1965). This equilibrium effect is

as a result of differences in chemical potential between the isotopes during which the

liquid water is in equilibrium with its vapour resulting into less isotopic ratio in the

vapour phase. Details about the values of the isotopic composition of all the samples

analyzed are shown in Appendix (1).

Figure 16: The mean isotopic compositions values during summer period. First value is

δ18

O, second value is δ2H.

48

Figure 17: The mean isotopic compositions values of winter samples. First value is

δ18

O, second value is δ2H.

5.2 Isotopic compositions of precipitation

There is a wide seasonal variation in the stable isotope compositions of the Precipitation

of the samples analyzed (Appendix 1). The δ18

O values varied between -8.640/00 to -

13.330/00 and δ

2H values varied between -62.12

0/00 to -93.65/00. The Annual mean

precipitation values for δ18

O and δ2H are -10.12

0/00 and -70.20

0/00 respectively. There is

a high correlation (r2= 0.99) between the isotopic compositions of precipitation in

Pudasjärvi region with a linear regression line

δ2H = 7.26δ

18O + 3.29 (29)

49

Based on (Figure 18) above, it was observed that most samples analyzed are very close

to the Global Meteoric Water Line (GMWL) and the Local Meteoric Water Line

(LMWL) has a lower slope and intercept compared to the GMWL. This is due to the

modification effect that occurs during rain falls as a result of partial evaporation of the

water drops and its reaction with atmospheric water vapor (Ingraham 1998). The

depleted δ values were found in the winter samples while the enriched values were

gotten during the spring-summer period. For example, during winter the δ18

O and δ2H

are -11.080/00 and -77.88

0/00 respectively while spring-summer period, the average

varied between (-9.37 and -9.53)0/00 for δ

18O and (-64.09 and -65.57)

0/00 for δ

2H. This

temporal variation of the isotopic data is attributed to kinetic isotope fractionation and

equilibrium exchange effects that occurs mainly during the secondary evaporation

process (Clark and Fritz, 1997).

Meteoric water lines obtained for Finland by Kortelainen and Karhu (2004) and Rokua

esker in the northern region of Finland by Isokangas (2013) were compared with

Pudasjärvi meteoric water line Figure (20). The Finnish meteoric water line (FMWL) is

shown in equation (30) below:

δ2H = 7.67δ

18O + 5.79 (30)

While the Rokua meteoric water line (RMWL) obtained by Isokangas (2013) is also

represented in equation (31) below:

δ2H = 7.77 δ

18O + 9.55 (31)

51

Figure (18) also reflects the source of water vapor and the effect of changes that occurs

during secondary processes of re-evaporation and mixing. It was observed that, the

Finnish, Rokua and Pudasjärvi water line all deviate from the global meteoric water line

but the Pudasjärvi water line has the highest isotopic variance probably due to small

amount of samples. The deviation of Finnish, Rokua and Pudasjärvi water line can be

attributed to amount effect (Dansgaard, 1964) and convective recycling effects that

enhance late spring and summer precipitation (Wassenaar et al., 2011) due to high

evapotranspiration rate in dry air and temperature during this period which is higher in

the northern part of Finland. It was observed that the isotopic composition values are

high during period of low rainfall and low during period of high rainfall.

5.3 The isotopic composition of surface water

The δ18

O and δ2H value for Kivarijoki River ranged from -14.75

0/00 to -10.31

0/00 with

mean value (-12.040/00) and -104. 88

0/00 to -79.55

0/00 with mean value (-87.89

0/00)

respectively while the δ18

O and δ2H value for Pudasjärvi Lake ranged from -13.75

0/00 to

-10.880/00 with mean value (-12.47

0/00) and -99.81

0/00 to -80.61

0/00 with mean value (-

91.220/00) respectively. The plot of surface water (Kivarijoki River and Pudasjärvi Lake)

isotopic compositions are shown in Figure (19) with the local meteoric water line. All

the samples plotted towards right of the LMWL. It is the reflection of the temporal

variability in isotopic composition of surface water due to fractionation effect. It is

obvious from the plot that the Kivarijoki River samples are more enriched in heavy

isotopes than the Pudasjärvi Lake samples, irrespectively of this, the highest depleted

value of δ18

O and δ2H (-14.7

0/00 and 104.88

0/00) are obtained during the winter period

from the same river. The river samples in this study are more enriched in heavy isotopes

compared to the lake samples; this could be as a result of direct river evaporation or

discharge of already evaporated water to the river by tributaries. For example, Ingraham

et al.,(1998) showed that River Murray in Australia was more enriched in heavy

isotopes than the local meteoric water due to evaporation and tributaries contribution,

resulting into 0.620/00 enrichment in heavy isotopes of hydrogen foe every 1% water for

loss by evaporation of the river.

52

Figure 19: Plot of δ18

O verse δ2H valves for 2006-2007 surface waters showing the

Evaporation water line (EVWL), Rokua meteoric water line and Pudasjärvi meteoric

water line.

Also, the seasonal variation in the surface waters was observed. The variation of the

isotopic composition of water was moderate, with (30.10% and 24.15%) and (20.87%

and 19.24%) for δ2H and δ

18O in Kivarijoki River and Pudasjärvi Lake respectively. Gat

(2010) noted that, seasonal changes that lead to enrichment of surface water

-120.00

-110.00

-100.00

-90.00

-80.00

-70.00

-60.00

-16.00 -15.00 -14.00 -13.00 -12.00 -11.00 -10.00 -9.00 -8.00

Kivarijoki (River)

Pudasjarvi (Lake)

RMWL

Pudasjärvi LMWL

EVWL

δ2H

(𝟎𝟎𝟎

⁄ V

SM

OW

)

Evaporation Water Line

δ2H = 5.87δ

18O -17.64

δ18

O ( ⁄ VSMOW)

53

composition during summer period could be attributed to heating of the surface layer,

while the later depletion in autumn is due to decrease in temperature gradient.

Nevertheless, the effect of ice formation could be seen on the surface water sample

especially in the lake samples. This is clearly reflected through the depleted values of

heavy isotopes obtained between November to early April. Gat (2010) explained further

that, the accumulation of snow which results into ice formation during winter influenced

the surface water composition, and could help in understanding whether the through-

flow of groundwater continues during the winter period.

The Pudasjärvi meteoric water line slope and d-excess (intercept) are (5.35% and

43.18%) and (6.56% and 65.55%) lower than both Finnish meteoric water line, and

Rokua meteoric water line respectively. It shows that evaporation effect is higher in the

northern region of Finland as expected.

5.3.1 Average isotopic composition of precipitation for Pudasjärvi

As a result of few precipitation samples used during this research and difference in the

location where the rainwaters were taken, it’s difficult to establish the real average

composition of precipitation for Pudasjärvi area. Nevertheless, the fact about the

average composition of precipitation was established at the point where both Pudasjärvi

Local Meteoric Water Line (LMWL) and Evaporation Water Line (EVWL) intercept

(Figure 19) and are expressed as

δ18

OP = -14.92 0/00

and

δ2HP = -106.47

0/00

To establish the uncertainty involved in this result due to the few water samples

analyzed, the interception point of Rokua meteoric water line (RMWL, collected 90 km

south from Pudasjärvi) with Evaporation Water Line (EVWL) was also noted and the

result obtained is shown below

54

δ18

OP = -14.10 0/00

and

δ2HP = -100.20

0/00

This reflects the signature of the precipitation that recharge the surface waters before

evaporation effects occur.

5.3.2 Effect of evaporation on isotopic composition of surface water body

As a result of evaporation on the surface water bodies, it was observed that, there was

enrichment in the oxygen-18 and hydrogen-2 values with a slope of 5.87 and d-excess

of -17.64. It’s obvious that the effects of evaporation will be greater in surface water

and this evidence was established in Figure (19) as both Kivarijoki River and Pudasjärvi

Lake deviated from the Local meteoric Water Line (LMWL).

The Evaporation water line for Pudasjärvi region is shown in Fig (19)

Evaporation Water Line: δ2H = 5.87δ

18O -17.64 (32)

It was noticed that the most divergent values relative to EVWL are enriched in oxygen-

18 which are during the spring and summer period

Further measures were taken to estimate the average evaporation loss on surface water

bodies during summer period. The parameters considered for the calculations are shown

in Table (3). The calculations were done based on equation (16) to (24) on chapter 4.2

55

Table 4: Parameters considered for the estimation of evaporation loss on

surface water bodies (Kivarijoki River and Pudasjärvi Lake) (OIVA,

2014)

The mean temperature value used in this context was obtained from OIVA (2014) for

the sampling period May 2006 to May 2007 through which the equilibrium

fractionation factor ( ) was obtained:

= −2.0667−0.4156 (103/276.6) +1.137(10

6/ (276.6)

2) = 11.29

The kinetic isotope fractionation ( ) value was obtained by substituting the relative

humidity value into equation (16)

O = 14.2 (1-0.65) 0

/00 = 4.970/00

While, the isotopic fractionation factor (α) = -1 = 10.29. The δ18

Op represents the

signature of the precipitations that recharge the surface water bodies before evaporation

effects occur and was obtained from the point where the LMWL intercepts with the

EVWL and where the RMWL intercepts with the EVWL, δ18

OA is the isotopic signature

Parameters Values based on

LMWL

Value based on

RMWL

T(0C) 3.4 3.4

T (K) 276.6 276.6

h 0.65 0.65

δ18

Op -14.920/00 -14.10

0/00

δ18

OA -26.210/00 -25.39

0/00

11.29 11.29

δ18

OL -11.760/00 -11.76

0/00

O 4.970/00 4.97

0/00

α 10.29 10.29

56

of ambient atmospheric moisture and δ18

OL is the isotopic signature of the surface water

bodies calculated based on summer values only.

However, the evaporation relative to water input is calculated based on equation (24)

and expressed below:

= (-11.76–(-14.92)) (1-0.65 + ) / (-11.76 + 1) ( + ⁄ ) +

0.65 (-26.21- (-11.76)) = 0.23

The evaporation to water input ratio based on LMWL was 0.23, which means the water

loss due to evaporation in the surface water bodies is approximately 23% and, the

residual water fraction (f) for Kivarijoki River and Pudasjärvi Lake is 77%. The

evaporation to water input ratio result based on RMWL was 0.17. i.e, 17% of water was

lost due to evaporation in surface water bodies. However, the results show that the

estimation of evaporation rate on surface water bodies using the δ18

O balance method

ranged within 17 to 23%. Some analytical uncertainties are involved in the calculation

and are expected to yield little deviation in the final result obtained. These uncertainties

may occur during, estimation of evaporation fluxes from the surface water, estimation

of isotope signature of precipitation which changed due to influence of a cold air

intrusion, the temperature and relative humidity may not represent the conditions when

the isotopic evaporation enrichment occurs.

5.4 Isotopic composition of groundwater

The isotopic composition of oxygen and hydrogen was analyzed from the groundwater

samples obtained from Pudasjärvi region between 2006-2007 and later in the year 2013.

These samples were extracted from different groundwater pipes namely: AK, OY1,

POR2, PVP8, PVP9, TK, VVO and 24.

Data from May 2006 to May 2007 and the year 2013 (Appendix 2) were considered in

this section and the isotopic composition during this period ranges from -12.280/00

57

obtained at point AK to -15.410/00 obtained at point OY2 for δ

18O and δ

2H values from -

95.550/00 at point AK to -110.19

0/00 at point OY2. The arithmetic mean of δ

18O and δ

2H

values for samples obtained between year 2006 to 2007 and later year 2013 for each

groundwater point is shown in Table (5).

Table 5: Arithmetic Mean of Groundwater Isotopic Composition

δ18O mean δ2H mean

Ak -13.41 -97.21

OY2 -14.19 -102.90

POR2 -13.51 -97.54

PVP8 -13.36 -95.47

PVP9 -13.12 -93.62

TK -13.73 -98.54

VVO -13.65 -98.62

24 -12.83 -91.61

This has a strong relationship with the distribution of δ18

O in the Finnish groundwater

presented by Kortelainen and Karhu (2004) as shown in Figure (11), on Chapter 3.5 of

this report.

The Pudasjärvi Groundwater Line was established by plotting its oxygen composition

against hydrogen composition. As a result of this, the linear correlation obtained is

shown in Figure (20) and its equation presented as:

58

Figure 20: Plot of δ18

O verse δ2H valves for groundwater samples including: (a) the

Local Meteoric Water Line is determined from the linear regression of all the

precipitation samples; and (b) Pudasjärvi Groundwater Line.

-130

-125

-120

-115

-110

-105

-100

-95

-90

-85

-80

-75

-70

-17 -16 -15 -14 -13 -12 -11 -10

AK

OY2

POR2

PVP9

PVP8

TK

VVO

24

Kivarijoki (River)

Pudasjarvi (Lake)

GMWL

Pudasjärvi LMWL

PudasjärviGroundwater LineEVWL

Pudasjärvi Groundwater Line

δ2H = 8.75δ

18O + 21.40

R2 = 0.9537

δ18

O ( ⁄ VSMOW)

δ2H

(𝟎𝟎𝟎

⁄ V

SM

OW

)

59

Pudasjärvi GWL: δ2H = 8.75δ

18O + 21.40 (33)

It was observed that the slope of Pudasjärvi GWL is a little bit higher compared to the

Finnish Groundwater equation (δ2H = 8.51δ

18O + 16.65) derived by Kortelainen (2004).

The GWL established for Pudasjärvi region has a high correlation value (r2= 0.954)

while its slope and deuterium excess are 2.74% and 22.20% respectively greater than

the Finnish groundwater line. The slope indicates that the groundwater isotopic

compositions are highly depleted in heavy isotopes.

In Figure (20), the isotopic of the groundwater values are heavily depleted and clusters

along the Global Meteoric Water Line (GMWL). This probably indicates that winter

precipitation is predominant in the groundwater and the samples are isotopically

conservative (Peng et al., 2012) and give an insight to the bias in the seasonality of

recharge and the nature of summer precipitation. However, the trend analysis of the

isotopic composition (δ18

O verse δ2H) of the groundwater samples shown in Figure (21)

and (22) show enrichment in the isotopic composition of groundwater observation pipe

24, PVP8 and PVP9 signifying the infiltration of surface water into the pipes. These

three (3) observation pipes are located in vicinity close to the flow path of Kivarijoki

River. As a result of few precipitation samples analysed, it is difficult to establish the

fact that groundwater reflects the isotope composition of average precipitation.

LMWL: δ2H = 7.26δ

18O + 3.29

R2 = 0.9972

60

Figure 21: The δ18

O values of groundwater observation pipes and surface water with

respect to time in 2006-2007 and in 2013

-18.00

-17.00

-16.00

-15.00

-14.00

-13.00

-12.00

-11.00

-10.00

-9.00

-8.00

AK

OY2

POR2

PVP8

TK

VVO

24

PVP9

Kivarijoki(River)

Pudasjarvi(Lake)

Time

δ1

8O

( 𝟎𝟎𝟎

⁄ V

SM

OW

)

Summer

Period

Winter

Period

Summer

Period

61

Figure 22: The δ2H values of groundwater observation pipes and surface water with

respect to time

-115.00

-110.00

-105.00

-100.00

-95.00

-90.00

-85.00

-80.00

AK

OY2

POR2

PVP8

TK

VVO

24

PVP9

Kivarijoki(River)Pudasjarvi(Lake)

δ2H

( 𝟎𝟎𝟎

⁄ V

SM

OW

)

Time

Summer

Period

Winter

Period

Summer

Period

62

5.5 Interaction between surface water and groundwater in the aquifer

Isotopic and geochemical tracers were employed to examine the contribution of

Kivarijoki River to the groundwater observation pipe located along its flow path. The

chemical concentration of the geochemical tracer used in the groundwater and surface

water were shown in Appendix (2). The pipes examined are PVP8, 24, and PVP9, but

observation pipe PVP9 seemed to be the closest to the river flow path.

Based on the result shown on Table (6), it was observed that, the concentration of SiO2

varied from one observation pipe to another pipe with time, the solute concentration

decreased during and after snow melt period. This pattern was similar to the stable

isotope tracer as the values of isotopic compositions of the samples changes with

seasons. The decrease in the concentration can be attributed to snowmelt and rainfall

penetrating the observation pipes and surface water. The mean silica concentration of

the surface water (9.23 mg/l to 12.14 mg/l) is higher compared to the concentrations of

the observed pipes (0.42 mg/l to 8.98 mg/l); it indicates surface water intrusion into the

PVP9 and 24. However, the high value of silica concentration in surface water can be

due to high Total dissolved solutions (TDS) and anthropogenic influence in the surface

water. Based on Table (1), the mean δ18

O values of precipitation are higher than the

ground water isotopic compositions. This indicates the contribution of an enriched δ18

O

value from precipitation to the groundwater with another source of lighter δ18

O value.

According to Okkonen (2011) report, the silica concentration of snow in the Pudasjärvi

area is less than 0.1 mg/l, and that of rainwater is generally less than 1 mg/l (Freeze and

Cherry 1979). This evidence can be seen in observed pipe PVP8 with a solute

concentration less than 1mg/l during and after snow melt period. This shows that pipe

PVP8 is predominately recharged by precipitation and snowmelt and also in line with

earlier discussion that groundwater is probably more of snowmelt based on groundwater

results placement on LWML.

The stable isotopes in Table (6) were calculated based on their mean values before and

after flood period. The mean values of δ18

O and δ2H before and after flood period in

63

kivarijoki River are -13.190/00 and -11.37

0/00 for δ

18O; and -95.51

0/00 and -84.64

0/00 for

δ2H. The values of pipe (24) are -12.91

0/00 and -12.77

0/00 for δ

18O; and -91.70

0/00 and -

90.780/00 for δ

2H. The values of pipe (PVP9) are -13.36

0/00 and -12.72

0/00 for δ

18O; and -

94.570/00 and -91.29

0/00 for δ

2H, while the values of pipe (PVP8) are -13.63

0/00 and -

12.990/00 for δ

18O; and -96.97

0/00 and -92.76

0/00 for δ

2H. However, the mean values of

the isotopic compositions of pipe PVP9 after the flood period are lighter; this indicates

that the infiltrated water has been affected by evaporation before entering the aquifer.

The isotopic composition of the groundwater samples and their solute concentrations

are classified based on seasonal variation (Table 5).

Table 6: Isotope compositions and solute concentration in pipes located

along Kivarijoki River flow path

Before Flood Period (Winter) δ18

O (0/00) δ

2H (

0/00) SiO2 (mg/l)

Kivarijoki River -13.19 -95.51 12.14

24 -12.91 -91.70 8.92

PVP9 -13.36 -94.57 8.98

PVP8 -13.63 -96.97 0.42

After Flood Period (Summer)

Kivarijoki River -11.37 -84.64 9.23

24 -12.77 -90.78 8.90

PVP9 -12.72 -91.29 8.65

PVP8 -12.99 -92.76 0.47

The fraction of river water in the observed pipes were calculated based on the binary

mixing model formula similar to equation (25), and the result obtained is shown in

Table (7).

=

(34)

Where CM is the δ18

O or SiO2 of the mixture; CP is the δ18

O or SiO2 of the precipitation

that recharge the surface waters before evaporation effects occur; Crw is the δ18

O or

64

SiO2 of the Kivarijoki River. Based on LMWL, the delta value of CP in this context is -

14.920/00, and -14.10% from RMWL and the solute concentration is 0.1 mg/l

The precipitation fraction are estimated based on equation (26)

Table 7: Calculated fraction of river water and precipitation in the

observed pipes using the isotope and geochemical tracers during summer

period

The fractional results (Table 7) show that 61%, 62% and 54% of Kivarijoki River

contributes to the recharge of groundwater in 24, PVP9 and PVP8 when the CP of

LMWL was considered in the calculation respectively, indicating that a higher

proportion of water in the pipes come from the surface water during summer period .

Furthermore, the fractional results of 49%, 51% and 41% were obtained when the CP of

RMWL was considered in the calculation and reflect that precipitation contributes a

greater proportion of water to 24 and PVP8 except pipe PVP9 that reflect high

proportion of surface water. It can be deduced from the results that the contribution of

Kivarijoki River to the pipe ranged from 49-61% with mean value (55%), 51-62% with

mean value (57%) and 41-54% with mean value (48%) in 24, PVP9 and PVP8

respectively during winter period. However, the SiO2 tracer result reflects high

proportion of Kivarijoki River contributions to pipe 24 (96%) and PVP9 (93%) but a

very low proportion of 4% to PVP8.

Tracer

Pipe

δ18O (LWML) δ18O (RMWL) SiO2

Summer Summer Summer

RW Fraction

Precipiation RW Fraction

Precipiation RW Fraction

Precipiation

Fraction Fraction Fraction

24 0.61 0.39 0.49 0.51 0.96 0.04

PVP9 0.62 0.38 0.51 0.49 0.93 0.07

PVP8 0.54 0.46 0.41 0.59 0.04 0.96

65

During the winter period, the isotopic composition of the Kivarijoki River was highly

depleted in heavy isotopes compared to its composition values during summer period.

The isotope compositions of the groundwater pipe PVP9 and PVP8 with the exception

of pipe 24 are similar to Kivarijoki River compositions values. This indicates the

predominance of precipitation (rainfall and snow) in the surface water body, PVP9 and

PVP8 during this period. However, the mixing fractions during the winter period are

shown in Table (8).

Table 8: Calculated fraction of river water and precipitation in the

observed pipes using the isotope and geochemical tracers during winter

period

The fractional results obtained based on CP of LMWL show that 73% and 90% of

precipitation recharge pipe PVP8 and PVP9 during winter period respectively.

However, 52% and 81% of precipitation contributes to the recharge of groundwater in

PVP8 and PVP9 when the CP of RMWL was considered in the calculation respectively

Therefore, the contribution of precipitation to the pipe ranged from 73-90% with mean

value (82%) and 52-81% with mean value (67%) in pipe PVP8 and PVP9 respectively

during winter period. This indicates that both pipes are recharged by precipitation

(winter/autumn rainfall and winter/autumn runoff).

On the other hand, the fractional result obtained for Pipe 24 is unrealistic because it has

values of 1.16 and 1.31 with CP of LMWL and RMWL respectively. These results can

be attributed to the high enriched value of heavy isotope in Pipe 24 compared to both

end members (CP and Kivarijoki River). Also, the composition of precipitation in PVP8

Tracer

Pipe

δ18O (LWML) δ18O (RMWL) SiO2

Winter Winter Winter

RW Fraction

Precipiation RW Fraction

Precipiation RW Fraction

Precipiation

Fraction Fraction Fraction

24 - - - - 0.73 0.27

PVP9 0.10 0.90 0.19 0.81 0.74 0.26

PVP8 0.27 0.73 0.48 0.52 0.03 0.97

66

pipe based on SiO2 tracer was 97% during winter, while PVP9 and Pipe 24 are 26% and

27% during winter respectively. The high recharged rate obtained from δ18

O of Pipe

(PVP9 and PVP8) and SiO2 tracer of Pipe PVP8 during the winter period can be

attributed to change in seasonal distribution of runoff. Based on Okkonen (2011)

research in the site, it was predicted that the surface water level will be higher compared

to the groundwater level throughout the year with the exception of January, August and

September as a result of increase in winter runoff and flooding. Thus, the increase in

snowmelt and rain during winter could cause decrease in spring flooding.

67

6 SUMMARY AND CONCLUSION

The aim of this project was to examine the groundwater recharge sources and quantify

the mixing ratio within the aquifers observed in Pudasjärvi area. In order to achieve this,

groundwater, surface water and precipitation samples were collected from the area

between year 2006 to year 2007 by Okkonen (2011) and later year 2013. The isotopic

compositions of the samples were analysed using Picarro L2120-I analyzer at the

University of Oulu water Laboratory while the solute concentration (SiO2) analysis has

been carried out by Okkonen (2011) during his previous research on the area. Both

results were used to estimate the mixing ratio of surface water infiltration into the

aquifer located along the Kivarijoki River flow channel.

Based on the isotopic compositions of the samples. The following conclusions were

drawn:

i) The isotopic compositions of the precipitation samples for the area resulted

to a local meteoric water line of δ2H = 7.26δ

18O + 3.29. The slope and

intercept of the local meteoric water line are 5.35% and 43.18% lower than

the Finnish meteoric water line (δ2H = 7.67δ

18O + 5.79). These variations

can be attributed to amount and convective recycling effects that enhanced

late spring and summer precipitation, which are mostly higher in the

northern part of the Finland. It was challenging to determine the average

weighted isotopic compositions of the precipitation due to few samples been

analyzed. Therefore, monthly precipitation sample should be taken in case of

future research.

ii) Through the isotopic composition of the groundwater samples, Local

groundwater line δ2H = 8.76δ

18O + 21.40 was established for Pudasjärvi

area. Groundwater samples were the heavy depleted except observation pipe

(24). It reflects the influence of winter runoff in the groundwater pipes and

shows the bias in seasonality of recharge including the nature of summer

precipitation.

68

iii) The surface water samples are highly enriched in heavy isotopes due to

fractionation effect. However, the evaporation water line established was

δ2H = 5.87δ

18O -17.64. The δ

18O and δ

2H value for Kivarijoki River ranged

from -14.750/00 to -10.31

0/00 with mean value (-12.04

0/00) and -104. 88

0/00 to -

79.550/00 with mean value (-87.89

0/00) respectively while the δ

18O and δ

2H

value for Pudasjärvi Lake ranged from -13.750/00 to -10.88

0/00 with mean

value (-12.470/00) and -99.81

0/00 to -80.61

0/00 with mean value (-91.22

0/00)

respectively.

The evaporation rate on surface water bodies in Pudasjärvi area was estimated

through evaporation to water input ratio (E/I) method. Factors taken into

consideration are: relative humidity of the area, isotopic composition of ambient

vapour, mean temperature during the study period, enrichment factor, kinetic

fractionation and equilibrium fractionation factors, the signature of the precipitation

that recharge the surface water before evaporation effects occur. Based on this

approach, the evaporation to water input ratio in the surface water bodies for

Pudasjärvi region ranged between 17 to 23%. Therefore, the residual water fraction

(f) ranged between 77 to 83%.

The relative contribution of Kivarijoki Rivers to observed pipe PVP9, 24 and PVP8

located along its flow channel were estimated using two end member mixing

analysis based on the isotopes and solute concentrations values. The isotopes and

geochemical tracer analysis indicate that recharge of pipes 24 and PVP9 are

predominately from surface water while pipe PVP8 is mainly recharged by

precipitation during summer period. However, the mixing ratio results obtained

through solute concentration analysis was very high compared to the results

obtained through stable isotopes during summer period. During winter period, both

PVP8 and PVP9 are recharged by winter/autumn rainfall and runoff. Based on the

tracers test, there is surface water intrusion into the aquifer even though the exact

amount can’t be established due to variation in the tracer’s results. However, it’s

69

advisable to keep the Kivarijoki catchment in good conditions, which in turns make

the esker groundwater also in a better condition.

Based on these results, the stable isotopes were more effective for quantifying

mixing ratio in an aquifer based on their conservative nature while solute tracer

(SiO2) was more of flow path tracer and its concentration varies after contact with

mineral and organic materials. Therefore, it would be advisable to combine both

tracers for better understanding of groundwater and surface water hydrological

interaction in order to get more reliable results.

Future studies should focus more on the biogeochemical processes within the

sediments in surface water bodies, their influence on the variation in solute

concentration and their impact on subsurface water. The seasons should also be

classified into summer, spring, winter and autumn period to understand better the

recharge scenarios in each period. The hydraulic head measurements should be

taken serious, as the direction of exchange flow depends on it. For better results

regarding groundwater and surface water interaction, more techniques should be

embraced, such as: simulating model of the area under study, thermal tracer methods

and analytical approach.

70

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Appendix 1 (1/2)

APPENDICES

Appendix 1: The results of isotopic analysis in (0/00)

Precipitation

Date δ18O δ2H

31.5.2013 -9.37 -64.09

1.8.2013 -10.41 -72.22

1.9.2013 -8.64 -58.93

9.10.2013 -13.33 -93.65

30.10.2013 -8.84 -62.12

Mean -10.12 -70.20

Surface Water

Date

Kivarijoki (River) Pudasjarvi (Lake)

δ18O δ2H δ18O δ2H

15.5.2006 to 18.5.2006 -12.45 -89.13 -12.99 -94.73

8.6.2006 to 30.6.2006 -10.78 -81.88 -10.95 -83.84

9.8.2006 to 31.8.2006 -10.31 -80.23 -11.10 -85.09

5.10.2006 -11.29 -84.4 -12.31 -89.61

1.11.2006 -12.09 -88.46 -13.33 -96.19

19.12.2006

-13.75 -97.28

17.1.2007 -14.63 -104.31 -13.63 -99.81

4.3.2007 to 7.3.2007 -14.75 -104.88 -13.39 -96.07

3.4.2007

-13.44 -96.23

31.5.2007 -11.93 -87.32 -12.26 -90.91

25.5.2009

-12.66 -92.10

9.7.2013 to 10.7.2013 -11.11 -79.55 -10.88 -80.61

27.8.2013 -11.29 -81.88 -11.22 -83.44

21.10.2013 -11.83 -84.76 -12.61 -91.15

Mean -12.04 -87.89 -12.47 -91.22

Appendix 1 (2/2)

Appendix 2

Appendix 2: The results of solute concentration (SiO2) in mg/l

Date AK OY2 POR2 PVP8 PVP9 TK VVO 24 Pudasjarvi

(Lake) Kivarijoki

(River)

9.8.2006 12 0.8 12 0.3 12 12 10 5.2 5.7

5.10.2006 11 0.7 13 0.4 11 12 13 11 8.2 11

1.11.2006 10 0.7 12 0.5 8.3 12 12 8.3 12 17

19.12.2006 10 0.7 13 0.6 8.7 12 13 8.5 7.8 7.7

17.1.2007 10 0.6 9.6 0.3 8.4 12 12 8.4 7 13

4.3.2007 10 0.3 8.6 0.3 8.5 12 12 8.4 14 12

3.4.2007 11 0.5 10 0.6 8.3 12 12 8.5 1.8 15

31.5.2007 10 0.3 7.6 0.5 9 12 12 8.2 7.2 7