J. Šedlbauer e-mail: josef.sedlbauer@tul.cz tel.: 48-535-3375

1. Contacts and materials J. Šedlbauer e-mail: josef.sedlbauer@tul.cz tel.: 48-535-3375 Materials for Environmental Chemistry: www.fp.tul.cz/kch/sedlbauer (link to the subject)

2. Syllabi 1/2 • Transport of chemicals and their distribution in the environment: parameters of the „environmental compartments“ model, thermodynamic description and data sources • Wet and dry atmospheric deposition, chemical equilibrium of rain droplets with acid-forming oxides, gas solubility • Solubility of solids and liquids in water, solubility of reactive gases - CO2 and carbonate formation • Transport of contaminants in soils and sediments • Model of bioaccumulation in food chains

3. Syllabi 2/2 + literature • Distribution of chemicals in the environment including advection and degradation processes • Kinetic model of wastewater treatment • Non-equilibrium transport of chemicals in the environment - diffusion • Summary: data, models and estimation methods for calculating the distribution of chemicals in the environment MACKAY D. Multimedia Environmental Models, CRC Press, 2001. MANAHAN S.E. Environmental chemistry, Lewis Publishers. , 2003. THIBODEAUX L.J. Environmental Chemodynamics, 2. Ed., J. Wiley. , 1995. web pages

4. Exam Seminar project Written exam – mostly calculations, a few theoretical quizzes (study materials can be used)

5. Why to care about chemicals in the environment? Environmental chemistry provides tools necessary to evaluate the fate of chemicals in the environment in both qualitative and quantitative way. Robert Boyle (1627-1691): „The task of chemistry is to study the essence of chemical compounds regardless of their utility“ About 100 000 chemicals are used industrially (European Chemical Bureau), at least 30 000 are transported in the environment, over 2000 chemicals on the EPA Priority Pollutant List Chemicals such as polychlorinated biphenyls dioxins, freons, some polyaromatic hydrocarbons… are purely human products Many chemicals (pharmaceuticals, pesticides) are directly designed to affect living organisms

6. Sources of environmentally important chemicals Hydrocarbons (aromatic, polyaromatic): oil Halogenated hydrocarbons: C1 – C3 - coolant media, solvents, aenestetics Aromatic – combustion, tar Biphenyls – isolation liquids Various structures – pesticides Oxygen compounds: Cresols and chlorophenols – combustion, disinfection Acetone, aldehydes – smog Humic acids – soil complexes Phtalates – increase plasticity of polymers Dioxines – combustion Nitrogen compounds: amines, amides, pyridines – dyes Sulfur compounds: thiols, benzenesulfonates – detergents Phosphorus compounds: organophosphates – pesticides Heavy metals: Hg, Pb, Cu, Sn, Cr etc.

7. „Laws“ of waste production THE NATURAL LAWS OF HAZARDOUS WASTE (Thibodeaux) __________________________________________________________ 1. I AM, THEREFORE I POLLUTE; undeniably, the production of some waste by beings and machines is not preventable. 2. RECYCLE, REUSE AND MINIMIZATION are only partial solutions to waste production. 3. CONVERT REMAINING WASTE to earthen-like materials that are environmentally compatible. 4. SMALL WASTE LEAKS ARE UNAVOIDABLE and acceptable. 5. NATURE SETS the standard for the earthen like forms and acceptable leak quantities. ________________________________________________

8. What decides about the distribution of chemicals - criteria Before setting regulation priorities, it is necessary to know the potential of chemicals to affect the environment – 4 criteria: Persistence(chemical reactivity and kinetic factors, P) Bioaccumulation potential(mobility from water or air to living tissues, BCF) Toxicity(biochemical factors, T) Potential of long-range transport(LRT) In addition, it is always necessary to estimate the amount, which we are dealing with. Environmental impact of a contaminant is a combination of all these factors.

9. What decides about the distribution of chemicals - examples Physico-chemical properties of chemicals can be very different (vapor pressure, solubility in water, reactivity…), which results in their very different distribution in the environment (e.g. freons quickly escape to the atmosphere and retain there for decades due to their non-reactivity, PCBs are primarily adsorbed on soil and sediment particles, the lifetime of alkenes in the atmosphere is only hours…) The most risky chemicals are non-reactive (i.e. long half-life of degradation), with high vapor pressure (distribution to atmosphere and an easy transport), hydrophobic (tendency to accumulate in fat tissues).

10. What do we actually mean by distribution of chemicals? Distribution of chemicals among environmental compartments (Environmental Partitioning) Environmental compartments are chemically and physically homogeneous media, which are separated from other media by a phase boundary (or boundaries). Due to complexity of environmental phases, their definition always depends on the applied level of approximation. Compartments: Most commonly considered are atmosphere, water, soil, sediments. Additional: snow and ice, aerosols, suspended colloids in water. Distribution to biota is sometimes evaluated a posteriori, because the most substantial transport occurs among abiotic compartments.

11. Four-compartment model

12. Eight-compartment model

13. Routes of transport

14. Model of distribution of chemicals among compartments The simple model of distribution is based on Nernst’s Law, which defines distribution coefficient between two systems with a phase boundary: Kij = (Ci / Cj )eq Ci , Cj are concentrations of a given compound in the two phases (environmental compartments) This relation is approximate and distribution coefficients depend on temperature – usually available only at 25°C and temperature dependence must be estimated.

15. Useful physico-chemical quantities Water solubility CS (mol m-3) Vapor pressure pS (Pa) Henry’s law constant H (Pa m3 mol-1) H = pS / CS Distribution coefficient octanol – water KOW Distribution coefficient organic carbon – water KOC (l/kg = mg/kgorguhlík_v_půdě / mg/lvoda) Partition coefficient soil – water KP = fOC KOC (fOC is the fraction of organic carbon in soil) Distribution coefficient biota – water Kb(closely related to KOWand BCF) Data: basic thermodynamic data are available e.g. at webbook.nist.gov/chemistry Specific data sources will be mentioned later

16. Fugacity model (Mackay) When all phases (compartments) are in equilibrium, fugacity of a compound is the same in each phase – this follows from thermodynamic intensive equilibrium criterion. For concentration in each phase: C = Z f f – fugacity of a compound (Pa) Z – fugacity capacity (mol m-3 Pa-1) It holds: Kij = (Ci / Cj ) = (f Zi / f Zj ) = (Zi / Zj )

17. Fugacity capacity - Z

18. Scheme of the equilibrium Environmental Compartments Model

19. mass ballance: Example of Level I fugacity model application Estimate the distribution of selected contaminants (naphthalene, anthracene, pyrene, phenol) among air, water and soil. Consider the relative proportions of these compartments as 11000:22:1 and the soil density as 2000 kg/m3

20. Example Level I - data Other needed data: Kp= 25,8 (exp. KOC for naphthalenefrom Bahnick and Doucette, 1988)

21. Basic parameters of environmental compartments Area and volume are not universal – locality dependent!

22. Example Level I – calculation and comparison CS = C / M = 0,242 mol m-3; H = pS / CS = 43,01 Pa m3 mol-1 Z1=4,034·10-4 mol m-3 Pa-1; Z2=0,02325 mol m-3 Pa-1; Z3=1,200 mol m-3 Pa-1 Assume e.g. M=100 mol: f=16,97 Pa; C1= 6,845·10-3 mol m-3; C2=0,3945 mol m-3; C3=20,36 mol m-3 m1= 75 mol; m2= 4.5 mol; m3= 20.5 mol

23. Higher level fugacity models Level II Assumes equilibria among compartments (the same as Level I), includes advection – degradation of a contaminant by chemical reactions (usually modeled by 1st order kinetics with half-life as a parameter) and the rate of income/outcome of a chemical between the considered systems and its surrounding environment (i.e. the sources and LRT are considered). Level III Does not require thermodynamic equilibrium among compartments, transport through the phase boundaries is controlled by diffusion (diffusion coefficients in all phases are required as parameters).