Environmental Chemistry of Organic Substances CHEM 651 Spring 2008

1. Environmental Chemistry of Organic Substances CHEM 651 Spring 2008

2. Course Objectives Objectives • identify primary sources of important classes of organic substances of environmental interest • understand and predict processes which govern the behavior and fate (phase transfer and reaction) of organic chemicals in the environment • obtain or derive important physicochemical properties of organic compounds • Rapidly assess the holistic environmental distribution of organic chemicals using simple distribution models

3. Organic Substances In The Environment • Environmental Organic Chemicals: Chemicals released into the environment as a result of human activities that affect human and ecosystem health at very low concentrations (i.e., ppm concentrations or lower); or natural (biogenic) organic substances that are useful as molecular markers of environmental processes. • S2ET2: the most important issues to study in environmental organic chemistry are sources, sinks, exposure, transport and transformation. Regulatory Chemistry • Various laws relate to the protection of environmental and human health. These laws are passed by Congress and signed by the President. A summary of the various laws is provided below. EPA is charged with administering these laws and develops technical, operational and the legal details.

4. Environmental Laws Important Environmental Legislation to Minimize Risk • Atomic Energy Act • Clean Air Act • Clean Water Act • Comprehensive Environmental Response, Compensation and Liability Act • Emergency Planning and Community Right to Know Act (EPCRA) • Endangered Species Act • Energy Policy Act • Federal Food, Drug and Cosmetic Act • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) • Federal Water Pollution Control Amendments • Marine Protection, Research, and Sanctuaries Act • National Environmental Policy Act

5. Environmental Laws (cont’) • Nuclear Waste Policy Act • Occupational Safety and Health • Ocean Dumping Act • Oil Pollution Act • Pollution Prevention Act • Resource Conservation and Recovery Act • Safe Drinking Water Act • Toxic Substances Control Act (TSCA) For more details, go to the following URL: http://www.epa.gov/lawsregs/laws/index.html

6. Regulatory Chemistry: Examples • Clean Air Act: Established funding and study for air pollutants in 1963; Congress passed legislation in 1970, and revised in 1990; EPA sets limits on certain air pollutants • Clean Water Act: Establishes limits of chemicals discharged into water bodies; first passed in 1972; established water quality criteria and TMDLs • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA): Established to provide federal control of pesticide distribution, sale, and use; EPA was given authority under FIFRA not only to study the consequences of pesticide usage but also to require users (farmers, utility companies, and others) to register when purchasing pesticides • Toxic Substances Control Act (TSCA): Established to give EPA the ability to track the 75,000 industrial chemicals currently produced or imported into the United States. EPA repeatedly screens these chemicals and can require reporting or testing of those that may pose an environmental or human-health hazard. EPA can ban the manufacture and import of those chemicals that pose an unreasonable risk.

7. Regulatory Chemistry (cont’) • Emergency Planning & Community Right-to-Know Act (EPCRA):Enacted by Congress in 1986 as the national legislation on community safety; this law is designed to help local communities protect public health, safety, and the environment from chemical hazards • Federal Food, Drug, and Cosmetic Act (FFDCA): Defines "pesticide chemical" to be any substance that is a pesticide under FIFRA, including all active and inert ingredients. Definition in previous law was limited to pesticides used in the production of a raw agricultural commodity; defines "pesticide chemical residue" to be a residue of a pesticide chemical, its metabolites, and degradates in or on raw or processed foods; allows EPA to except a substance from these definitions, if its origin in food is primarily natural or resulting from non-pesticidal use • Environmental regulations drive research • New regulations need to be scientifically based

8. Hazard & Risk and Risk Reduction • The purpose of environmental chemistry is to minimize the risks associated with chemicals used by society • Hazard is a function of toxicity and exposure and related to potential harm Hazard = fn{Toxicity x Exposure} • Toxicity relates to the inherent sensitivity of the organism to a chemical and the mechanism of biological effect • Exposure is related to the following scheme: Structure of chemical  Physical and Chemical Properties  Chemical Reactivity in Environment (distribution and degradation)  Transport to Biological Receptor • Risk relates magnitude of hazard and probability of its occurrence Risk = fn{hazard x probability of occurrence}

9. Role for Environmental Chemistry • TSCA inventory contains 70,000 substances that have not been fully evaluated; list is growing rapidly • How do you ensure risk minimization with such a large inventory of chemicals? • Many chemical properties are not available through empirical measurements • Chemical design: how can we better design chemicals to be environmentally friendly and non-toxic? Green Chemistry

10. Leading Environmental Pollutants • Silt (erosion from farmlands and urban/suburban regions) • Nutrients (agricultural/urban runoff) • Metals (urban runoff, industrial discharge, energy production, transportation) • Toxic Organics (agricultural/urban runoff, energy production, transportation; industry) • Pathogens (feed lots, wastewater) • Organic matter: (wastewater, runoff)

11. Emissions & Source Terms • Emissions: mode of entry of organic contaminants in the environment and quantity of inputs • Point sources: specific and determinable sites of entry that can be regulated, e.g., pipe discharge, smokestack plumes • Non-point sources: diffuse or multiple sites of entry that are not easily regulated, e.g., agricultural runoff, atmospheric deposition, volatilization from land surfaces

12. Some Critical Observations on Organics • Egg shell thinning in Pelicans by DDT (1960’s) - led to Rachel Carson’s book “Silent Spring” • Ozone depletion by CFCs (1970’s – Nobel prize by Rowland and Molina) • Food chain biomagnification of synthetic chemicals (1970’s) • Global dispersal of organochlorines (1980’s) • Health problems in polar Aboriginal populations (1990’s) • Nature versus nurture in public health issues (present): causes of cancer, hormonal regulation and other diseases

13. Toxics Loading and Release Inventory • EPCRA • TLRI: toxics loading and release inventory. Industries required to document use and releases of chemicals to the environment. Information is available on the web (http://www.epa.gov/tri). • Each year TRI inventory is compiled and eventually published.

14. TLRI 2000 Figures Total releases of chemicals regulated according to TRI 7.1 billion pounds (2000) Total PBT releases 12 million pounds (2000) Source: www.epa.gov/tri

15. Water Quality Conditions in the US A profile from the 1998 national water quality Inventory report to congress • ~40% of lakes, streams and estuaries sampled were not clean enough to support fishing and swimming activities throughout the US • Rivers: 842,426 mi assessed, 35% polluted • Lakes: 17,390,370 acres assessed, 45% polluted • Estuaries: 28,687 sq mi assessed, 44% polluted

16. Water Quality is Affected by Land Use Pressure • ~4 million people live in Metro DC region • By 2030 ~19 million people will reside in Bay watershed • Human development has substantially altered the nature of watersheds • Watershed land use is divided between natural forested, urban, and agricultural Source: http://chesapeake.usgs.gov/

17. Principal Sources - Identifying where chemicals come from Energy Production Ag Fertilizers Urban Horticulture Sewage Discharge Auto emissions

18. Example Watersheds in Chesapeake Bay Showing Land Use Diversity Susque R. Chesterville Br. Anacos R. Basin Area (km2) 70,000 15.8 440 Land Use Cover (%) Agricultural 31 93 <5 Mixed Urban 5 <1 54 Forest 62 6.8 25

19. Forested Land

20. Agricultural Land Use

21. Suburban Land Use

22. Urban Land Use: Substantially Altered Landscape

23. Example Source Profile: N Sources to The Bay Source: Deposition of Nitrogenous Pollutants in the Chesapeake Bay Watershed (2002) State Advisory Board on Air Pollution • 70-75% of N is NO3- • Basin states contribute ~50% of atmospheric N • Atmospheric emissions derived from up to 36 states

24. Comparison of Land Use v. Runoff Ag fertilizer application often occurs in fall Urban runoff comparable to Ag but sustained through the year; multiple sources Forests act to buffer N runoff through denitrification; very low N loadings in streams Source: http://ww.cbf.org

25. Hydrosphere Atmosphere Biota Major compartments are further divided into sub-compartments Air – air, aerosols Water – water, particles, colloids Soil – soil, air, water, colloids “The environment” is defined by 4 major compartments Geosphere • Chemicals can be introduced into atmosphere, hydrosphere or geosphere • Chemicals move between 4 major compartments through bulk or diffusive transport processes (arrows) • Bulk transport depends on mass transport of phase (air, water particles, etc.) and chemical concentration in phase • Diffusive transport depends on physical and chemical properties and concentration differential between compartments

26. Chemical Fate Cartoon Arrows indicate pathways

27. Global Air Circulation & Global Distribution Net PCB Transport is toward poles; grasshopper effect; dependent on physical & chemical properties Source: http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Easterly_Waves/Trade_Winds/Trade_Winds.html

28. Chemicals of Concern • Persistent, bioaccumulative, and toxic substances (PBTs) • Example PBTs • PAHs (polycyclic aromatic hydrocarbons) • PCBs (polychlorinated biphenyls) • Dioxins and Furans • Pesticides • PBDEs (Polybrominated diphenyl ethers) • Phthalate Esters • Emerging Contaminants • Pharmaceuticals (human and vet) & Personal Care Products • Perfluorinated acids (derived from Teflon) • Fragrances • Detergents • Biogenic Substances • Steroids • Aromatic hydrocarbons

29. Xenoestrogens • Some contaminants interfere with the normal hormonal regulation of estrogen • Evidence becoming more widespread of “feminization” effect in males of aquatic species • Examples of important environmental estrogens • Organohalogen compounds (esp. those that bind strongly to the AH receptor) • Pesticides • n-Nonyl phenol (detergents) • Pharmaceuticals (esp. some steroids)

30. Naphthalene Benzo(a)pyrene Phenanthrene Pyrene Polycyclic Aromatic Hydrocarbons (PAHs)

31. Rules for PAH Nomenclature 1. The structural formula is written with the greatest possible number of rings lying in a horizontal row. 2. Horizontal and vertical axes are drawn through the center of the longest horizontal row in such a way that maximal number of rings (those which are not lined up horizontally) are placed in the upper right quadrant and the minimal number of rings in the lower left quadrant. 3. Carbon atoms are numbered in a clockwise direction starting with the carbon atom that is not a part of another ring and is in the most counterclockwise position of the uppermost ring or, if there is a choice, of the uppermost ring farthest to the right. Carbon atoms common to two or more rings are not numbered. 4. Ring faces, which are not common to two rings, are lettered in alphabetical order with the side between carbon atoms 1 and 2 designated "a". Alphabetical order is continued clockwise around the molecule. 5. Compounds (or isomers) formed by the addition of a component are named with numbers and letters enclosed in brackets. These are placed immediately after the name of the added component to describe where a substituent group is attached or where a ring is fused to the face of the molecule. Appropriate letters are used where a ring is fused to more than one face of the molecule. 6. The structural formulas used show aromatic rings as plain hexagons and a methylene group as CH2

32. Example: benzo(a)pyrene a q r 12 1 p 12a 11 2 o b l 10 m 10b 12b 10a 3 9 n c 12c 3a k d 4 8 6a 5a e j i h g f 5 7 6

33. Sample Problems Draw the following structures: 1. Benzo{e}pyrene [contrast with benzo(a)pyrene]; propose another way to name this chemical 2. Dibenz{a,h}anthracene 3. Fluoranthene (hint = benzo{j,k}fluorene) 3. Benzo{b}fluoranthene & benzo{k}fluoranthene

34. Major PAH Sources • Fossil Fuels (runoff & discharges) • Petroleum spills • Coal piles • Pyrolysis (carbon combustion) • Coking operations • Utilities (energy production) • Automobiles (transportation) • Incineration (waste reduction) • Asphalt (weathering of paved surfaces) • Natural Sources • – Diagenesis • – Catagenesis

35. Free Radical Condensation • Formation of PAHs by pyrolysis • Reaction scheme proposed by Connell • Occurs in industrial furnaces

36. Polychlorinated Biphenyls (PCBs) General Molecular Formula C12H10-nCln IUPAC Nomenclature

37. Polychlorinated Biphenyls (PCBs) • Uses • Large capacitors & transformers: dielectrics (~90%) • Hydraulic & lubricating fluids • Plasticizer and/or fireproofing agent • Sources • Incomplete combustion of PCB waste • Vaporization of PCB in open use applications • Leakage from closed systems (transformers) • Illegal disposal

38. PCB Facts • 2x109 kg produced worldwide commercially; production peaked in 1960’s • Banned in July 1979 (TSCA) • Solely of anthropogenic origin • Industrial applications used Aroclor mixtures, e.g., 1242, 1248, 1254, and 1260 12 = # C atoms 42 = average wt% chlorine in technical mixture • Congener distribution (10 homologues) mono = 2 penta = 46 nona = 2 di = 12 hexa = 42 deca = 1 tri = 24 hepta = 24 tetra = 42 octa = 12 209 Congeners + atropisomers

39. PCBs in the Environment • PCBs are globally distributed, and tend to be highly concentrated in polar organisms • PCBs have low water solubilities, favoring uptake into sediments and biota • PCBs are lipophilic and bioconcentrate • PCBs are a particular problem in Arctic regions because of reliance of endemic populations on high fat diets • PCBs are a “toxics of concern” in the Chesapeake Bay region because of a high bioconcentration in aquatic organisms and potential health effects in humans

40. counts 80000 70000 60000 50000 40000 30000 20000 10000 0 10 20 30 40 50 60 70 min GC-ECD Chromatogram of PCBs PCBs present as a complex mixture and are difficult to separate and analyze in environmental samples Response Time, min

41. Dioxins and Dibenzofurans • Dioxin & Dibenzofuran Sources • Municipal incineration (C + Cl-) • Paper mill pulp waste (2 Cl2-Ar-OH yields 2,3,7,8-TCDD) • Combustion of organic matter; can be derived from natural sources

42. Chlorodibenzo-p-dioxins Chlorodibenzofurans 2,3,7,8-TCDD 2,3,7,8-TCDF

43. Phthalate Esters • Used to increase flexibility of PVC-based polymers as a softener • Up to 50% (wt/wt) content in some plastics • 5-20 millions tons produced annually • There are 18 commercially important PEs • Most of high MW PEs used in PVC products (>DBP) • Some phthalates show estrogenic effects (DBP) • DEHP makes up ~50% of phthalate ester use DEHP- Di-(2-ethylhexyl) phthalate DBP – Di-(n-butyl) phthalate

44. Pesticides • Very biologically active and diverse group of compounds used in crop protection and horticulture • Herbicides • Triazines • Chloroacetamides • Ureas & thioureas • Thiocarbamates • Phenoxy acids • Oximes • Insecticides • Organochlorines • Organophosphorus derivatives • Carbamates • Pyrethroids

45. Aldicarb (oxime carbamate) Diazinon (organophosphorus) Atrazine (triazine) Chlordane (organochlorine) Alachlor (chloracetamide) Linuron (urea)

46. Polybromodiphenyl Ethers • High production volume chemicals used primarily as fire retardants in many common clothing items, upholstery, and hardware • 132,000 t/year produced globally in 2002; amounts increasing • 30% of brominated flame retardants are BDPEs BDE 47 BDE 99 BDE 47 2,2’,4,4’-tetrabromo DPE BDE 99 2,2’4,4’,5 -pentabromo DPE BDE 209 decabromo DPE BDE 209

47. PDBE Production and Properties • PBDE products produced by brominating diphenyl ether in the presence of a catalyst (e.g., FeBr3) • There are theoretically 209 PBDE congeners (like PCBs) • Major technical products contain mainly pentaBDEs octaBDEs and decaBDE • Log Kow values for PBDEs range from 5.9 to 10 • Vapor pressures are very low • Very low water solubilities • PBDEs have potential for global dispersal

48. Pharmaceutical Chemicals • Divided into human and veterinary pharmaceuticals • Primary source to surface waters is wastewater discharge or runoff from animal feedlots • Trends in population and demographics correlate with increasing drug use • Many drugs are excreted intact or as liable conjugates • Important class of emerging contaminants • Tend to have high solubilities in water and have rapid degradation rates • High potential biological activity in non-target organisms is greatest concern

49. Naproxen (+)-2-(6-Methoxy-2-naphthyl)-propionic acid Ibuprofen (+)-2-(4-Isobutylphenyl) propionic acid Oxytetracycline 4-(dimethylamino)-1,4,4a,5,5a, 6,11,12a-octa-hydro-3,5,6,10,12,12a-hexa-hydroxy-6-methyl-1,11-dioxo-naphthacenecarboxamide Triclosan 5-chloro-2-(2,4-dichlorophenoxy) phenol

50. Fluorinated Organic Chemicals • Derived from the degradation of perfluorinated polymers, such as Teflon, and are used as surfactants, fire retardants and lubricants Perfluorooctanesulfonamide R Perfluorooctanoic Acid (fluoropolymer production, foams and varnishes) Perfluorooctanesulfonic Acid (surfactants & fire retardants)