1

Integrated acidification study and survey on acid rain impacts

in China

Soil and soilwater interactions

The Environmental Chemistry groupDepartment of ChemistryUniversety of Oslo, Norway

SteppingstonesSteppingstones inin our our Cooperation withCooperation with ChinaChina

19881988:: Cooperation with Cooperation with ResearchResearch center forcenter for EcoEco--Environmental SciencesEnvironmental Sciences, CAS, CAS19921992: Catchment: Catchment studies withstudies withGuizhou Institute ofGuizhou Institute of EnvironmentalEnvironmental Science Science &&Chongqing Inst. ofChongqing Inst. of EnvironEnviron. Science and. Science and MonitoringMonitoring19951995:: Collaboration agreement betweenCollaboration agreement betweenThe Norwegian ministry of environment The Norwegian ministry of environment andand SEPASEPA19961996: PIAC: PIAC fundedfunded by by Norwegian Agency for Development CoNorwegian Agency for Development Co--operationoperation (NORAD) (NORAD) and theand the World BankWorld Bank--ASTENASTEN19961996: PIAC: PIAC cooperation withcooperation with SEPA SEPA && CREASCREAS19971997: PIAC: PIAC cooperation withcooperation with South China Institute ofSouth China Institute of BotanyBotany, CAS, CAS

PIACPIACPlanningPlanning of anof an Integrated ACidificationIntegrated ACidification study study

andand surveysurvey onon acid rain impactsacid rain impacts in Chinain ChinaNorwegianNorwegian participantsparticipants::

In NorwayIn Norway: : Norwegian Institute of InternationalNorwegian Institute of International AffairsAffairsNorwegian Institute for AirNorwegian Institute for Air ResearchResearchNorwegian Institute forNorwegian Institute for Forest ResearchForest ResearchThe Norwegian foundation The Norwegian foundation forfor naturenature andand cultural heritage researchcultural heritage researchNorwegian Institute for WaterNorwegian Institute for Water ResearchResearchUniversity of OsloUniversity of Oslo

The PIACThe PIAC projectprojectEstablish contacts Obtain an overview Evaluate needsSelection of sites

WhyWhy AlAl leaching mechanismsleaching mechanismsare important to understandare important to understand

Al isAl isMobilisedMobilised inin acidification processesacidification processesToxicToxic toto plantsplants andand aquaticaquatic faunafauna

ToTo predict future effectspredict future effects ofof acidification acidification we mustwe must bebe ableable toto predictpredict futurefuture AlAl--concentrationsconcentrations

UnderUnder variousvarious anthropogenicanthropogenic deposition scenariosdeposition scenariosIn differentIn different environmentsenvironments

OverviewOverview (After(After BergrenBergren && MulderMulder, 1995), 1995)

Al in primary minerals

Al in secondarymineral phases

Al adsorbedby SOM andexchangeable

Adsorbed Al(OH)3and Al in secondary minerals

Al3+ (aq)

Al(OH)2+Al(OH)2 +

Al(OH)F+

AlSO4+ AlF2+AlF

2 +

Slowly Slowly reactingreactingsolidsolid phasesphases

Rapidly Rapidly reactingreactingsolidsolid phasesphases

1. Gibbsite1. GibbsiteSolubilitySolubility && IonexchangeIonexchange

Al(OH)Al(OH)3 3 (S)(S) + 3H+ 3H++ = Al= Al3+3+ + H+ H22OO

MayMay bebe expressedexpressed as:as:

pAl = 3pH +pAl = 3pH + pKpK

Reported values varymore than afactor 1000

Most reported valuesfor soilwater are

less than 3

2. 2. IonIon exchangeexchangewithwith base cationsbase cations

E.g. CaE.g. Ca2+2+::2Al2Al3+3+ + 3CaX = 3Ca+ 3CaX = 3Ca2+2+ + 2AlX+ 2AlX

TheGaines Thomas constant

is difficoult toestimate

3.3. Jurbanite Jurbanite SolubilitySolubility/Co/Co--adsorptionadsorption

Al(OH)SOAl(OH)SO4 4 (S)(S) + H+ H++ = Al= Al3+3+ + + SOSO4422-- + H+ H22OO

MayMay bebe expressedexpressed as:as:

pAl = pH pAl = pH -- pSOpSO4 4 ++ pKpKsp sp

ChallengeChallengeTheThe relationships betweenrelationships between

soilwater chemical parameters as pH, pSOsoilwater chemical parameters as pH, pSO44 and pAland pAlexhibitexhibit largelarge spatial variationspatial variation

TheThe questquest is tois to findfind::A simpleA simple soilsoil chemical parameterchemical parameterthatthat,, together with keytogether with keywater chemical parameters,water chemical parameters,decribesdecribes the Althe Al--activityactivity

4. SOM4. SOM--AlAlComplexationComplexation

AlAl complexedcomplexed to solidto solid Soil OrganicSoil Organic MatterMatter

{ }{ }

RAl H RH Al

RH

RAl

(3 ) 3

(3 )

− + + +

+

− + +

+ ⇔ +

=

aa

a

a a

a

KAl

HRAl

3

4. SOM4. SOM--AlAlContCont..

Rearranging the equationgives:

Approximation to identifyable parameters

gives:

{ } { }

{ }

Al RHRAl

K H

RHRAl

Al

pY pK

3(3 ) RAl

(3 )

3

RAl*

+

− +

+

− +

+

=

≈

=

= +

aa

a

aa

tot

org

tot

org

CAl

Y CAl

xpH

Amount of Carbon in soil

Al extracted with e.g. pyrophosphate

13

StrategyStrategy

ByBy analysing soilanalysing soil & soilwater& soilwater samplessamples from from differentdifferent environments we find empirical environments we find empirical relationships betweenrelationships between pAl, pH andpAl, pH and AlAlpyropyro/C/C

OtherOther relevant water parameters: SOrelevant water parameters: SO4422--, Ca, Ca2+2+, I, I

OtherOther relevantrelevant soilsoil parameters: Alparameters: AlCuClCuCl22,,AlAloxox

Field studiesField studiesPrecipitationPrecipitationThroughfallThroughfallSoilSoil waterwaterStreamStream waterwaterSoilsSoils

N

100 m

Liu Chong Guang siteSoil water samplers

Bottles for sample collection

Soil Soil

Throughfall sampler

IonsIons inin precipitationprecipitation µeq/L

HUMEXBirkenes Kosetice Czerniawka

Ratanica LCG TSP Guangzhou0

100

200

300

400

500

Locations

Ca2+Mg2+

Na+K+

NH4+

H+

NO3-

Cl-SO4²-

Norway CzechRepublic

Poland China

0.6 1.1

9.1

1.6

4.4

5.3

8-10

8-10

ExchangeableExchangeable cations incations in soilssoilsChinaChina PolandPoland/Norway/Norway

LeigongLeigong

ChonghuaGuiyang

NanshanTieshanPing

NanshanSiminanShan

LeigongDingHuShan

DingHuShanHeShan

DingHuShanBai Yun HUMEX

BrennaIngabekken

RatanicaJanow

BirkenesCzerniawka

Ciekon0

20

40

60

80

100

meq

/kg

BS HS AlS

13 11 11 83 34 31 44 53 47 26 37 39 34 22 7 58 30 28 16 43 26 74

IonsIons inin soilsoil waterwater

TieShanPingLiuChongGuang

RatanicaJanow

CzerniawkaBrenna

CiekonIngabekken

BirkenesHUMEX

0

200

400

600

800

1000

1200

1400

1600µe

q/L

H+ Ali NH4+ Na+K Ca+Mg SO4 NO3 F- Cl-

ChinaChina PolandPoland NorwayNorway

""Critical loadCritical load ratio"ratio"Al/(Ca+Mg)Al/(Ca+Mg)

““TheThe deposition below which significant harmful effectsdeposition below which significant harmful effectsdo notdo not occur accordingoccur according to presentto present knowledgeknowledge””

How doesHow does real soilwater datareal soilwater data fitfit the the GibbsiteGibbsite modelmodel??

3 4 5 6 7 82

4

6

8

10

12

pH

pAl

pK=-8.11

pK=-10.8

O

H

A

B

C

InIn manymany (most)(most) casescases the gibbsitethe gibbsite model model doesdoes notnot describedescribe the data at pH < 4.5the data at pH < 4.5

What doesWhat does the data tell us ?the data tell us ?

Gibbsite:Gibbsite:pAl =pAl = pKpKspsp + 3pH+ 3pH

Empirical fittingEmpirical fitting::pAl = pKpAl = pK00 ++ apHapH

ReussReuss et al., 1990: ret al., 1990: r22=0.75=0.75pAl = pAl = --2.29 + 1.65pH2.29 + 1.65pH

pKpKspsp::--8.118.11((synteticsyntetic))--10.8 10.8 ((amorphamorph))

Locality Hor. N r2 a pKAll All 797 0.58 1.6 -2.6

Birkenes H 85 0.93 1.7 -2.4Tieshanping A 44 0.84 1.7 -2.8Czerniawka A 15 0.94 2.6 -7.2Guiyang B 53 0.76 1.8 -4.0Tieshanping B 43 0.82 1.6 -2.7Guiyang C 84 0.80 1.7 -3.1Czerniawka C 70 0.87 2.2 -5.7Birkenes C 46 0.92 2.0 -4.3

DoesDoes thethe Jurbanite model describeJurbanite model describe thethefieldfield datadata better thanbetter than the Gibbsitethe Gibbsite modelmodel ? ?

0 2 4 6 8 10-14

-12

-10

-8

-6

-4

pK = pAl + pSO4 - pH (Jurbanite)

pK =

pA

l - 3

pH (G

ibbs

ite)

O

H

A

B

C

What doesWhat does the data tell us ?the data tell us ?pKsppKsp: 3.8: 3.8

((NordstomNordstom, 1982), 1982)JurbaniteJurbanite::pAl = pH - pSO4 + pKsp

EmpiricalEmpirical::pAl = apH + bpSO4 + pK

Locality Hor. N r2 a b pKAll All 796 0.63 1.6 0.7 -4.8Tieshanping All 86 0.83 1.5 0.5 -3.8Guiyang All 213 0.70 1.5 0.1 -2.8Czerniawka All 174 0.78 1.7 2.6 -12.5Birkenes All 214 0.57 1.3 0.4 -2.4

Birkenes H 84 0.93 1.6 0.3 -3.3Tieshanping A 43 0.84 1.6 0.3 -3.3Czerniawka A 14 0.95 2.7 -1.3 -2.7Tieshanping B 43 0.86 1.4 1.2 -5.6Guiyang C 83 0.80 1.7 0.1 -3.6Czerniawka C 69 0.87 2.2 0.4 -7.0Birkenes C 45 0.92 1.9 -0.3 -2.9

How doesHow does real datareal data fitfit the the SOMSOM--AlAl modelmodel ??

3 4 5 6 70

2

4

6

8

pH

pY

H

O

A

B

C

SOMSOM--AlAl modelmodelWesselinkWesselink et al., 1995: ret al., 1995: r22=0.82=0.82

pYpY = = --1.84 + 1.14pH1.84 + 1.14pH

Locality Hor. N r2 a pKAll All 295 0.67 1.6 -3.7Guiyang All 119 0.60 1.4 -2.9Czerniawka All 136 0.77 1.8 -4.6

Guiyang A 35 0.42 1.1 -1.9Czerniawka A 11 0.37 1.6 -3.1Guiyang B 35 0.62 1.3 -2.2Ratanica B 9 0.44 1.7 -4.0Guiyang C 42 0.65 1.2 -1.7Czerniawka C 45 0.82 3.0 -10.1

{ }pY p pK apH*RAl=

= ++Al3 C

Altot

org

What doesWhat does the data tell us ?the data tell us ?

ModelModel developmentdevelopment

pAl ispAl is empirically correlatedempirically correlated to:to:pH, pSOpH, pSO4 4 && p(p(AlAlorgorg//CCtottot))

We hypothesise that Al-mobilisation is controlledby a combined SOM-Al mechanismand sulfate desorption

RAlRAlnn++((nn½SO½SO4422--)+(3)+(3--nn)H)H++=RH =RH 33--nn+Al+Al3+3++(n½)SO+(n½)SO44

22--

pAl =pAl = pKpKSOMSOM--AlAl+ (3+ (3--n)pH n)pH -- (n½)pSO(n½)pSO4 4 + p(+ p(AlAlorgorg //CCTotTot))

Fitted empiricalFitted empirical to all data:to all data:pAl = pAl = -- 3.52 + 1.6 pH 3.52 + 1.6 pH -- 0.03 pSO4 + 0.8p(0.03 pSO4 + 0.8p(CCTotTot//AlAlpyropyro))

ModelModel testingtesting

pp∆∆ = = --loglog[(Σ[(Σ(10(10--pAlpAlmeasuredmeasured -- 1010--pAlpAlmodelledmodelled))22)/N])/N]1/21/2

GibbsiteGibbsite pAl = pAl = --2.6 + 1.6pH2.6 + 1.6pHJurbaniteJurbanite pAl = pAl = --4.8 + 1.6pH + 0.7pSO4.8 + 1.6pH + 0.7pSO44

SOMSOM--AlAl modelmodel pAl = pAl = --3.7 + 1.6pH + p(3.7 + 1.6pH + p(CCTotTot//AlAlorgorg))New combinedNew combined modelmodel pAl = pAl = --3.5 + 1.6pH 3.5 + 1.6pH -- 0.03pSO0.03pSO44 + 0.8p(+ 0.8p(CCTotTot//AlAlorgorg))

GibbsiteGibbsite JurbaniteJurbanite SOMSOM--AlAl NewNew

pp∆∆Alle 3.65 3.62 3.62 3.74Ciekonek 3.72 3.71 3.76 3.79Ratanika 4.21 4.42 4.19 4.51Guiyang 3.51 3.41 3.97 3.91Janow 4.07 4.10 3.47 3.71Czerniawka 3.53 3.73 3.66 3.69Tieshanping 3.92 3.57Birkeland 3.89 4.14

ConclusionsConclusions from from AlAl--mobilisation studiesmobilisation studies

DifferentDifferent mechanisms controlmechanisms control the Althe Al--mobilisation mobilisation dependingdepending on e.g. pH range and sulfateon e.g. pH range and sulfate concentrationsconcentrations

ComplexationComplexation of Al toof Al to soil organicsoil organic matter (SOMmatter (SOM--Al)Al) maymaydescribedescribe AlAl--activityactivity in mostin most Chinese soil watersChinese soil waters

In regions of high S-deposition Al mobilisationis best described by an combined pH dependent Al dissolution and sulfate desorption (“Jurbanite model”)

A combination of SOMA combination of SOM--AlAl dissolutiondissolution and and mobile anionmobile anion mobilisation appears promisingmobilisation appears promising

ConclusionsConclusions fromfrom field studiesfield studies

Very highVery high depositiondeposition ofof sulfursulfur atat some sitessome sitesWaterWater acidification onlyacidification only in small 1. orderin small 1. order streamsstreamsSoilSoil & soilwater& soilwater acidificationacidification isis likelylikely in largein large areasareas

LargeLarge spatial variationspatial variation inin soil chemistrysoil chemistryHighHigh concconc. of Al in. of Al in soilsoil water,water, but alsobut also high Cahigh Ca2+2+-- concconc..

Development in Development in S and CaS and Ca2+2+ deposition criticaldeposition critical

Laboratory experimentsLaboratory experimentsSoil columnsSoil columns:: Batch experimentBatch experiment::

1

1

2

Soil A Soil B

ConclusionsConclusions fromfromlaboratory experimentslaboratory experiments

SimpleSimple batch experiments yieldbatch experiments yield samesame resultsresults as moreas morecomprehensive soil column leaching experimentscomprehensive soil column leaching experimentsSulfateSulfate adsorptionadsorption onon YellowYellow-- and Redand Red soilsoil isis lowlowAlAl mobilisation correlatesmobilisation correlates best tobest to soilsoil pH andpH and AlAlorgorg

The base cationThe base cation weatheringweathering isis lowlow

Future soilFuture soil waterwater acidification depends acidification depends stronglystrongly onon changeschanges in base cationin base cationdepositiondeposition inin additionaddition to Sto S--depositiondeposition

Model workModel work

SimpleSimple equationsequations for:for:CationCation exchangeexchangeGibbsiteGibbsite solubilitysolubilitySulfateSulfate adsorptionadsorptionWeatheringWeatheringChargeCharge balancebalance

Model calibrationModel calibrationHindcastHindcast

ModelModel runningrunningSimulationSimulation && ForcastForcast

Magic simulationsMagic simulations

1970 1980 1990 2000 2010 2020 2030 2040 20500

0.2

0.4

0.6

0.8

Year

RC

L

No change +30%: Ca,Mg,SO4 - 80%: Ca,Mg,SO4

-30%: Ca,Mg -30%: SO4 +30%: SO4

1970 1980 1990 2000 2010 2020 2030 2040 20505

10

15

20

25

30

Year

BS

%

ConclusionsConclusions fromfrommodel studiesmodel studies

SoilSoil & soilwater& soilwater acidification may occuracidification may occur inin SouthernSouthern China China underunder longlong termterm acid depositionacid depositionPresentPresent deposition loadingdeposition loading givesgives minor changesminor changes

AnAn increaseincrease in sulfatein sulfate depositiondeposition or or aa decreasedecrease in base cationin base cation deposition deposition givegive rise torise to accelerated accelerated soilsoil and soilwaterand soilwater acidificationacidification

ConclusionsConclusions from PIACfrom PIACPrecursors for the formation of O3 and other photooxidants occur at high levels

Increased emissionsIncreased emissions of NOof NOxx may leadmay lead totoseriously increasedseriously increased OO33--concentrationsconcentrations

Damage to vegetation may be attributable to high levels of SO2, O3, lack of P or high Al content in soil water.Ecological effects of acidificationhave been observed on surface water organismsWaters low in dissolved saltsare found in rural areas with low acid loading at present

These watersThese waters areare poorly bufferedpoorly bufferedandand thereforetherefore very vulnerable tovery vulnerable to acidificationacidification