Chemical Properties & Contaminant Classescfcc.edu/blogs/srowe/files/2015/08/5-Chemical-Properties-and... · Physical-Chemical Properties of the Compound ... Behavior of Chemicals

Chemical Properties & Contaminant ClassesAN ENVIRONMENTAL CHEMISTRY INTRO

Lecture 5 – Fall 2016

MSC-210 – Marine Environmental Sampling & Analysis

Environmental Chemistry• Environmental Chemistry:

The study of sources, reactions, transport, and fate of chemical entities in the air, water, and soil of environments, as well as their effects on human health and the natural environment.

• Antoine-Laurent de Lavoisier (1743-1794)• Paris, France

• 1789, published Elementary Book of Chemistry

• Atmospheric environment

• Animal Respiration

• Combustion

September 2015 CFCC MSC-210 2

Role of Environmental ChemistryCharacteristics of the Molecule

• Surface area, molecular weight (mw), functional groups, chemical bonds, etc.

Physical-Chemical Properties of the Compound

• Aqueous solubility, vapor pressure (vp), melting point (mp), Octanal/Water partitioning, etc

Transformation & Distribution in the Environment

• Persistence, transportation, bioaccumulation, biomagnification, etc.

Biological Effects

• Lethal toxicity, reduction in growth, reduction in reproduction, etc.


Behavior of Chemicals• Governed by:• Physical-Chemical properties

• Transformation processes

• Degradation processes

• Physical-Chemical Properties include:• Molecular weight (mw)

• Boiling point (bp)

• Melting point (mp)

• Solubility in water

• Vapor pressure (vp)


Basic ChemistryCRASH COURSE

The Atom


• Nucleus contains Protons & Neutrons:◦ Protons: positively charged

◦ Neutrons: no charge

• Electron shells contain Electrons:◦ Electrons: negatively charged

◦ Very small, almost negligible mass

◦ Valence Shell: outer electron shell

p+n

p+p+

p+

p+

np+

n

nnn

e-

e-

e-

e-

e-

e-

Not to scale

p+

n

e-

The Atom


• Atomic Number: number of protons in the nucleus

• Atomic Mass: mass of the atom

Molecules


Physical States of Matter• Solids• Definite volume & shape

• Molecules have a fixed relationship to one another

• Liquids• Definite volume, but variable shape

• Molecules free to move among each other

• Gases• Indefinite volume, indefinite shape

• Molecules free to move among each other

• Molecules far apart


Increasin

g Energy

Physical-Chemical Properties:• Melting Point (mp):• The temperature at which a substance changes from solid to

liquid at atmospheric pressure.• At the melting point, the solid and liquid phase exist in

equilibrium

• Boiling Point (bp):• The temperature at which a substance changes from liquid to

gas at atmospheric pressure.• At the boiling point, the vapor pressure of the liquid becomes

sufficient to overcome atmospheric pressure and allow bubbles of vapor to form inside the liquid.


Physical-Chemical Properties:• Vapor Pressure (vp):• The pressure that is exerted by a liquid

• Directly related to bp

• Aqueous Solubility:• How soluble a substance is in water

• Solubility tables

• Solute

• Solvent

• Solution

• Precipitant


• Hydrophilic• Lipophobic

Physical-Chemical Properties:• Lipid Solubility:• How soluble a substance is in lipids/fats

• Hydrophobic

• Lipophilic

• Bioaccumulation

• Biomagnification


Properties of SubstancesSubstance

Molecular Formula

Environmental Occurrence

Physical State

Melting Point (°C)

Boiling Point (°C)

Oxygen O2

21% of atmosphere

Gas -218 -183

Nitrogen N2

78% of atmosphere

Gas -210 -196

Water H2OOceans, lakes, rivers

Liquid 0 100

CommonSalt

NaCl 3.5% of seawater Solid 801 1413

Quartz SiO2

Rocks, sand, geological strata

Solid 1610 2230


Organic vs. Inorganic

Organic Compounds Inorganic Compounds

Formed mainly of Carbon (C), Hydrogen (H), Oxygen (O), andNitrogen (N) – having a “backbone” of Carbon and Hydrogen

Simple molecules formed by atoms of any element; typically do not contain both Carbon (C) and Hydrogen (H)

Lower melting points Higher melting points

Lower boiling points Higher boiling points

Generally, less soluble in water Generally, more soluble in water

Examples: Sugars, Lipids, Amino Acids

Examples: H2O, CO2, NaCl


Contaminant Classifications LEGACY POLLUTANTS & EMERGING CONTAMINANTS

MAJOR CHEMICAL -USE CLASSES

MAJOR ENVIRONMENTAL CONTAMINANT GROUPS

Legacy Pollutants

Well known pollutants that were introduced in the past (many of which have since been banned, or strictly regulated), that are still present and causing problems in the environment today.


Key Characteristics of Legacy Pollutants• Persistence

• Bioaccumulation

• Biomagnification

• Global Fate & Transport

• Bioavailability

• Bioaccessibility

• Acute Toxicity and/or carcinogenicity

• Endocrine Modulations


Legacy Pollutants: Examples

Organic Inorganic

PCBs Mercury

DDT Sulfur

Chlorinated Hydrocarbons Nitrate

Petrol, Fuel Oil Arsenic

Explosives Copper

Herbicides Lead

Insecticides Chromium

Rodenticides Radioactive Waste


Contaminants of Emerging Concern (CECs)

Pollutants that either:

- have only recently been detected in the environment due to advances in analytical instrumentation;

or

- are from more recently developed materials and products with widespread use in everyday life.


CECs: Examples


Persistent Organic Pollutants (POPs)

Polybrominated Diphenyl Ethers (flame retardants, foams, plastics, etc.)

Perfluorinated Organic Acids

Organochlorine pesticides

Pharmaceuticals & Personal Care Products (PPCPs)

Human prescribed drugs and over-the-counter medications

Bactericides, antimicrobials, antibiotics, anti-fungals

Sunscreens

Veterinary medications

Endocrine-Disrupting Chemicals (EDCs)

Synthetic and natural estrogens and androgens

Nanomaterials

Cosmetics, Sunscreens, Carbon Nanotubes

Environmental Compartments & Chemical FugacityCHEMICAL TRANSPORT & FATE


Environmental Compartments

26

ParticulatesAir

WaterParticulates

Porewater

Soil Biota

Sediment

September 2015 CFCC MSC-210

27September 2015 CFCC MSC-210

Environmental Chemodynamics


FugacityFugacity: ◦ the tendency of a compound to escape from

one environmental compartment into another one

◦ Latin term fugere, “to flee”

◦ Chemicals escape from compartments in which they have high fugacities to those of low fugacity


Two-Phase Partitioning Partitioning of a chemical into two adjacent, immiscible phases

(compartments) can be described mathematically as:

C1 = K(C2)n

or

LogC1 = LogK + nLogC2

Using these equations, partitioning coefficients for different phase interactions can be calculated…


Partition Coefficients

31

Media Partition

Coefficient & Equation

Description

Air-Water KH

KH = Pair

Cwater

Relationship between the partial pressure of the chemical in air & the corresponding concentration in water

Octanol-Water

KOW

Kow = Coctanol

Cwater

Relationship between hydrophilic & hydrophobic phases

Biota-Water

(BioconcentrationFactor)

KB (BCF)

KB = Cbiota

Cwater

Characterizes the magnification of concentrations through the food chain; hydrophobicity important

Particle-Water

(Soil Sorption)

KOC

KOC = Corg carbon

Cwater

Characterizes relationship between solid & liquid phases to determine mobility in soils, sediments, and particles; solubility important


Partition CoefficientsFortunately, these values can be looked up…and modeled!

For general physical-chemical property information regarding common hazardous contaminants:◦ ATSDR – Toxicological Profile Sheets

For physical-chemical properties and environmental fate estimation:◦ US EPA – Estimation Program Interface (EPI)

For estimating chemical fates and exposures:◦ US EPA – Exposure & Fate Assessment Screening Tool (E-FAST)


http://www.atsdr.cdc.gov/toxprofiles/index.asp

https://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program-interface

https://www.epa.gov/tsca-screening-tools/e-fast-exposure-and-fate-assessment-screening-tool-version-2014

Trends• Persistent & Bioaccumulating Organic Pollutants:

◦ Low aq. solubility

◦ High logKOW

◦ High logBCF

◦ High logKOC


Let’s look at some chemical profiles…ATSDR Toxicological Profiles:

• DDT, DDE, DDD

• PCBs

• Pyridine

• Formaldehyde (CH2O)

• Mercury


http://www.atsdr.cdc.gov/toxprofiles/index.asp#P

Let’s look at some chemical profiles…ATSDR Toxicological Profiles:

Chemical Aq. Sol. logKOW logBCF logKOC

DDT

PCBs

Pyridine

CH2O

Mercury


http://www.atsdr.cdc.gov/toxprofiles/index.asp#P

ReferencesLecture Content

• Connell, D.W. (2005). Basic Concepts of Environmental Chemistry, 2nd ed. Boca Raton, FL: CRC Press, Taylor & Francis Group.

Images

• Title Slide: • Drawing Chemical Formula

http://www.presentermedia.com

• Slide 5: • Chemistry Lab clipart

http://www.openclipart.org

• Slide 8:• O2 – http://www.ck12.org

• H2O – http://www.openstudy.com

• Slide 9: • H2O bonds - http://commons.wikimedia.org

• Ionic bonding – http://study.com

• Slide 10: • States of Matter http://www.britannica.com

August 2015 CFCC MSC-210 36

http://www.presentermedia.com/

http://www.openclipart.org/

http://www.ck12.org/

http://www.openstudy.com/

http://commons.wikimedia.org/

http://study.com/

http://www.britannica.com/

ReferencesImages (cont’d)

• Slide 25: ◦ Block Diagram

www.usgs.gov

• Slide 26: • Green fish

www.iconshut.com

•Slide 27:• Contaminant transport/Chemodynamics

www.simmakers.com

•Slide 28:◦ Chemical movement

www.usgs.gov

Slide 29◦ Boiling in beaker

www.fallriverschools.org

August 2015 CFCC MSC-210 37

http://www.usgs.gov/

http://www.iconshut.com/

http://www.simmakers.com/

http://www.usgs.gov/

http://www.fallriverschools.org/

Documents

Chemical Properties & Contaminant Classescfcc.edu/blogs/srowe/files/2015/08/5-Chemical-Properties-and... · Physical-Chemical Properties of the Compound ... Behavior of Chemicals