Showing papers in "Environmental Science & Technology in 1988"

Octanol-water partition coefficients of polychlorinated biphenyl congeners

Abstract: Octanol-water partition coefficients (K{sub OW}) for 13 polychlorinated biphenyl (PCB) congeners were accurately determined by the generator column technique. These values were used to confirm a highly significant linear relationship between log K{sub OW} and the logarithm of the relative retention time on a nonselective gas chromatographic stationary phase. The total surface areas (TSA) for all the PCB congeners were determined by assuming planar molecules, van der Waal's radii for component atoms, and appropriate values for solvent radius, bond angles, and distances. The TSA was highly significantly correlated with log K{sub OW} and the relationship used to calculate log K{sub OW} values for all the PCB congeners. Further development of these relationships gave an expression for aqueous solubility which can be used to calculate the solubility for these PCB's where appropriate data are available.

Photocatalytic production of hydrogen peroxides and organic peroxides in aqueous suspensions of titanium dioxide, zinc oxide, and desert sand.

Abstract: The formation of H_2O_2 and organic peroxides in illuminated aqueous suspensions of ZnO, TiO_2, and desert sand in the presence of O_2 and organic electron donors has been studied. The photocatalytic rate of formation of H_2O_2 on ZnO was shown to depend on the O_2 partial pressure, on the concentration of organic electron donors, and on the concentration of H_2O_2.

Chromate removal from aqueous wastes by reduction with ferrous ion

Abstract: Experimental measurements of reaction stoichiometries indicate that optimum conditions for chromate removal from oxygenated, 25/sup 0/C aqueous wastes by reduction with ferrous ion occur at pH less than 10.0 in solutions containing the following anions: ClO/sub 4//sup -/, Cl/sup -/, F/sup -/, NO/sub 3//sup -/, and PO/sub 4//sup 3 -/. At pH greater than 10.0 and at lower pH in solutions that contain greater than 10/sup -4/ M total phosphate, chromate is less efficiently reduced by ferrous ions as evidenced by nonstoichiometric reduction. Nonstoichiometric reduction of the chromate by the ferrous ion is caused by the competitive oxidation of the ferrous ions by dissolved oxygen. Depending on pH and solution composition, the reduction of chromate by ferrous ions causes rapid precipitation of (Cr/sub x/Fe/sub 1-x/)(OH)/sub 3/(s). The solubility of this solid limits Cr(III) concentrations, between pH 5.0 and pH 11.0, to less than the drinking water limit of 10/sup -6/ M.

Organochlorine contaminants in arctic marine food chains: accumulation of specific polychlorinated biphenyls and chlordane-related compounds

Abstract: Polychlorinated biphenyl congeners (S-PCB) and chlordane-related compounds (S-CHLOR) as well as DDT, hexachlorocyclohexane, toxaphene, and chlorobenzenes were determined in pooled arctic cod (Boreogadus saida) muscle and polar bear (Ursus maritimus) fat and in the blubber and liver of 59 ringed seals (Phoca hispida) from the east-central Canadian Arctic. S-PCB concentrations ranged from 0.0037 mg/kg (wet wt) in cod muscle to 0.68 mg/kg in male seal blubber and 4.50 mg/kg in bear fat. Tri- and tetrachloro PCB homologues were the dominant PCBs in fish, while pentachloro/hexachloro and hexachloro/heptachloro congeners predominated in ringed seal blubber and polar bear fat, respectively. Chlordane compounds detected in seal blubber were oxychlordane, cis- and trans-nonachlor, and cis-chlordane as well as nine minor components of technical chlordane, including nonachlor-III (a nonachlor isomer). Toxaphene and HCH isomers were the major organochlorines in cod muscle with mean concentrations of 0.018 and 0.010 mg/kg, respectively. S-CHLOR/S-PCB ratios ranged from 0.6 in fish muscle and bear fat to 0.7-0.9 in seal blubber, much higher than observed in more southerly marine environments, suggesting a proportionally greater input of chlordane into the Arctic.

Trophodynamic analysis of polychlorinated biphenyl congeners and other chlorinated hydrocarbons in the Lake Ontario ecosystem

Abstract: The bioaccumulation of polychlorinated biphenyl (PCB) congeners and some other chlorinated organics in the Lake Ontario ecosystem has been studied. In addition to the classical biomagnification of PCBs and some of the other organics, the chlorine content of the PCBs was observed to increase with trophic level. Most of the differential PCB fractionation seemed to occur at the lower end of the food chain (water to plankton to mysid). At the higher trophic levels (mysid to smelt to salmonid), the PCBs seemed to be distributed as a uniform composition mixture. The bioaccumulation factor of these hydrophobic organics increased linearly with octanol-water partition coefficient of the chemicals at all trophic levels. The environmental bioaccumulation of these chemicals in salmonids was higher than that predicted from bioconcentration from water alone, showing that contaminated food is a major source of these chemical residues in fish.

Organochlorine contaminants in arctic marine food chains: identification, geographical distribution and temporal trends in polar bears.

Abstract: Contamination of Canadian arctic and subarctic marine ecosystems by organochlorine (OC) compounds was measured by analysis of polar bear (Ursus maritimus) tissues collected from 12 zones between 1982 and 1984. PCB congeners (S-PCB), chlordanes, DDT and metabolites, chlorobenzenes (S-CBz), hexachlorocyclohexane isomers (S-HC-H), and dieldrin were identified by high-resolution gas chromatography-mass spectrometry. Nonachlor-III, a nonachlor isomer in technical chlordane, was positively identified for the first time as an environmental contaminant. S-PCB and S-CHLOR accounted for >80% of the total organochlorines in adipose tissue. Six PCB congeners constituted approximately 93% of S-PCB in polar bears. Levels of most OCs were lowest in the high Arctic, intermediate in Baffin Bay, and highest in Hudson Bay. Levels of ..cap alpha..-HCH were evaluated in zones influenced by surface runoff. Levels of S-CHLOR were four times higher and levels of the other OCs were two times higher in adipose tissue of bears from Hudson Bay and Baffin Bay in 1984 than in adipose tissue archived since 1969 from these areas; levels of S-DDT did not change.

Metals in aquatic systems.

Abstract: In this article we address the general question of whether we can yet predict metal-scavenging residence times in natural systems based on current knowledge about metal behavior as derived from laboratory studies. Although we will show that our ability to predict metal behavior is still relatively limited, such a conclusion should not be construed as a criticism of the reductionist approach. Rather, it should be seen that a number of challenges remain for surface chemists interested in the natural environment.

Destruction of pollutants in water with ozone in combination with ultraviolet radiation. 3. Photolysis of aqueous ozone.

Abstract: Etude permettant de determiner si la photolyse de l'ozone en solution aqueuse donne une production directe de peroxyde d'hydrogene ou une production directe de radical hydroxyle

Bioconcentration of organics in beef, milk, and vegetation

Abstract: Mise en evidence de correlations entre les facteurs de concentration biologiques des elements organiques de l'environnement (pesticides, dioxine) et leur coefficient de partage entre octanol et eau

Partitioning of arsenic and metals in reducing sulfidic sediments

Abstract: The sediment in a reservoir on the Clark Fork River in western Montana is contaminated with arsenic, copper, zinc, and other elements. This sediment is the source of groundwater contamination in the adjacent alluvial aquifer, and this study elucidates the processes transferring arsenic to the groundwater by the formation of diagenetic sulfides in the sediment. Vertical trends in a core through oxidized surface sediment into reducing sediment below show that concentration and partitioning of metals and arsenic are controlled by the redox interface. Solid phases of arsenic, copper, and zinc change from dominantly oxyhydroxide and organic phases to sulfide phases across the interface. Arsenic, copper, zinc, manganese, and iron in the pore water are controlled by the solubility of iron and manganese oxyhydroxides in the oxidized zone and metal sulfides in the reduced zone. The change in redox conditions upon burial results in a system where the growth of diagenetic copper, zinc, and arsenic sulfides controls the distribution and partitioning of metals and arsenic in the sediment and the speciation and release of arsenic to the adjacent groundwater system.

Photochemical formation of hydrogen peroxide in natural waters exposed to sunlight.

Abstract: Hydrogen peroxide is formed in most natural waters when they are exposed to sunlight. The rate at which H/sub 2/O/sub 2/ accumulates is related to the concentration of light-absorbing (>295 nm) organic substances in these waters. The photochemical accumulation rate of H/sub 2/O/sub 2/ in sunlight has been measured for several surface waters and ground waters and was found to be 2.7 /times/ 10/sup /minus/7/ to 48 /times/ 10/sup /minus/7/ mol L/sup /minus/1/ h/sup /minus/1/, in waters ranging from 0.53 to 18 mgL/sup -1/ dissolved organic carbon (DOC), respectively. These rates were determined in midday sunlight, 0.4 W m/sup /minus/2/ (295-385 nm), latitude 24.3/degrees/ N. Apparent quantum yields of H/sub 2/O/sub 2/ have been determined for natural waters at different wavelengths. These quantum yields decreased with increasing wavelength, from 10/sup /minus/3/ in the near-ultraviolet to 10/sup /minus/6/ in the visible spectral range. The quantum yields have been used in a photochemical model to calculate H/sub 2/O/sub 2/ accumulation rates of natural water samples. Model calculations agree with H/sub 2/O/sub 2/ accumulation rates obtained from exposing three different water samples to sunlight.

Henry's law constants of some environmentally important aldehydes

Abstract: The Henry’s law constants of seven aldehydes have been determined as a function of temperature by bubble-column and by head-space techniques The compounds were chosen for their potential importance in the polluted troposphere and to allow structure-reactivity patterns to be investigated The results (at 25 oC) are as follows (in units of M atm^(-1)): chloral, 344 X 10^5; glyoxal, ≥ 13 X 10^5; methylglyoxal, 371 X 10^3; formaldehyde, 297 X 10^3; benzaldehyde, 374 X 10^1; hydroxyacetaldehyde, 414 X 10^4; acetaldehyde, 114 X 10^1 A plot of Taft’s parameter, ∑σ^*, vs log H^* (the apparent Henry’s law constant) gives a straight line with a slope of 172 H^* for formaldehyde is anomalously high, as expected, but the extremely high value for hydroxyacetaldehyde was unexpected and may indicate that α-hydroxy-substituted aldehydes could have an unusually high affinity for the aqueous phase The intrinsic Henry’s law constants, H, corrected for hydration, do not show a clear structure-reactivity pattern for this series of aldehydes

The influence of humidity, sunlight, and temperature on the daytime decay of polyaromatic hydrocarbons on atmospheric soot particles.

Abstract: In this paper we have attempted to quantify the loss of polyaromatic hydrocarbons (PAH) on atmospheric soot particles with respect to the effects of humidity, solar radiation, and temperature. Dilute residential wood smoke and internal gasoline combustion emissions were individually aged in the presence of natural sunlight in 25-m/sup 3/ outdoor Teflon film chambers. Soot particles were collected on filters and analyzed for PAH. In each experiment first-order rate constants were computed for the disappearance of individual PAH. Rate expressions as a function of humidity, light, and temperature were then generated for nine different PAH from the wood smoke experiments. Estimates suggest that, at moderate humidities and temperatures. PAH half-lives in the chamber atmosphere were of the order of 1 h. At very low angle sunlight, very low water vapor concentrations, or very low temperatures. PAH daytime half-lives on airborne soot particles increased for many compounds to a period of days.

Receptor models: development and testing of such models has moved from the research domain into application to practical problems

Abstract: Air pollution authorities use models to develop optimal control strategies for air pollutants. According to the traditional approach, emissions inventories for various sources are used as inputs for plume, box, or grid models to predict ambient concentrations of total suspended particulate matter (TSP), SO/sub 2/, or other air pollutants. These methods, however, are inadequate for many purposes today and will be even less useful for many future needs. Even if dispersion models were accurate, the source emissions inventories upon which they rely are not. Source emission inventories, especially for sources equipped with pollution controls, usually do not include contributions from fugitive process emissions and dust. Furthermore, air quality standards are beginning to require knowledge of source of particles in certain size ranges, particles bearing certain toxic substances, or particles that have a special role in problems such as visibility degradation or climate modification.

Interactions of metals and protons with algae.

Abstract: Proton uptake by intact algal cells was found to consist of two processes: (1) a fast (<4 s) surface reaction and (2) a slow (2h) diffusion of protons into cells. A pH titration technique measured only the rapid surface reaction that forms negative sites at higher pH. Adsorption of alkali, alkaline earth, and transition metal ions on algae was quantitatively represented by the Langmuir adsorption isotherm with its two parameters y/sub m/, the maximum amount of metal adsorbed, and K, the equilibrium constant taken as a measure of bond strength. Variations of these parameters with pH and type of metal indicate that metals adsorb to algal surfaces by electrostatic attraction to negative sites, such as carboxylate anions of poly(galaturonic acid) (pectin), as previously suggested.

Physical-chemical properties of chlorinated dibenzo-p-dioxins

Abstract: Reported and newly determined experimental data for aqueous solubility, octanol-water partition coefficient, vapor pressure, and Henry's law constants of the polychlorinated dibenzo-p-dioxins are presented and reviewed. Correlation equations are derived for these properties as a function of chlorine number and molar volume, which enable the solubility and octanol-water partition coefficients of most congeners to be estimated with an accuracy within a factor of 2 and vapor pressure and Henry's law constant within a fador of 5. It is suggested that properties of homologous series are best correlated by a two-stage process. In the first stage, treated here, simple correlations are developed to establish approximate values as a function of molar volume and chlorine number. This should be followed by a more rigorous second stage treating isomer differences and using more refined molecular descriptors. The data presented here should be sufficiently accurate for many environmental assessment purposes.

A thermodynamic-based evaluation of organic chemical accumulation in aquatic organisms

Abstract: A thermodynamic-based (the fugacity model) approach and a kinetic bioenergetic based (the food chain model) approach to predicting organic chemical concentrations in aquatic organisms yield dichotomous conclusions regarding the existence of biomagnification. The former indicates that biomagnification is not possible while the latter has concluded in several applications that biomagnification is a dominant process for hydrophobic chemicals. This paper examines biomagnification by evaluating laboratory and field data relative to the two models. Ratios of fugacities in field animals and water are generally above 1 and increase with trophic level and the hydrophobicity of the chemical. This finding is consistent with the food chain model but violates the assumption of the fugacity model that maximum ratio value is 1. It is concluded that food chain transfer can result in an increase in concentration with trophic level. This increase appears to be significant for chemicals with octanol-water partition coefficients greater than about 10/sup 4/.

Distribution of volatile organic chemicals in outdoor and indoor air

Abstract: The EPA volatile organic chemistry (VOC) national ambient data base (Shah, 1988) is discussed. The 320 chemicals included in the VOC data base are listed. The methods used to obtain the data are reviewed and the availability, accessibility, and operation of the data base are examined. Tables of the daily outdoor concentrations for 66 chemicals and the daily indoor concentrations for 35 chemicals are presented.

Humic Acid Complexation of Calcium and Copper

Abstract: High-affinity metal binding by isolated humic acids has been observed for both copper and calcium in metal titration experiments. Results of titrations of humic acids with a single metal (either calcium or copper) are consistent with a discrete ligand site model of humate-metal binding. However, copper titrations in the presence of excess calcium do not show competitive effects predicted by such a model. Hence, different ligand sites must be involved in calcium and copper binding, or a binding mechanism other than discrete ligand binding must be operative.

Photolysis of polycyclic aromatic hydrocarbons adsorbed on fly ash

Abstract: Degradation photochimique de ces composes adsorbes sur des particules atmospheriques. Les conditions operatoires ont ete selectionnees de facon a simuler l'environnement rencontre par les particules liees aux HPA

Cloudwater chemistry from ten sites in North America

Abstract: Cloudwater and rainwater samples were collected at 25 m above ground during 2 years from 10 nonurban sites in North America On the average, cloudwater collected from sites in the eastern United States was more acidic and had higher concentrations of NO/sub 3//sup -/ and SO/sub 4//sup 2 -/ than that at sites in the western United States and Puerto Rico Of all the sites in the network, cloudwater from Maine had the highest concentrations of these ions Concentrations of hydrogen ion, nitrate, and sulfate were significantly higher in cloudwater than in rainwater at most sites; however, on a paired-event basis, enrichment factors for cloud vs rain varied greatly In contrast to distributions of inorganic anions, the concentrations of formate and acetate in cloudwater and rainwater were similar at sites in the western and eastern United States, suggesting that these compounds originated primarily with natural rather than anthropogenic sources

Developing national sediment quality criteria

Abstract: La methode faisant intervenir les coefficients de partition est utilisee pour controler les teneurs en composes hydrophobes dans les sediments

Occurrence and bioaccumulation of organochlorine compounds in fishes from Siskiwit Lake, Isle Royale, Lake Superior.

Abstract: A wide range of chlorinated organic compounds was measured in different size classes of lake trout (Salvelinus namaycush namaycush) and whitefish (Coregonus culpeaformis neohantoniensus) from Siskiwit Lake, a remote lake on Isle Royale in Lake Superior. Our results confirm the long-range transport of several chlorinated pesticides and polychlorinated biphenyls (PCBs) and, in addition, indicate that technical chlordane constituents, octachlorostyrene, pentachloroanisole, and decachlorodiphenyl ether also are transported to remote locations. Chemical concentrations as a function of fish age (size) were not similar between species and were not consistent among compounds. Differences in bioaccumulation with age between species for a given compound indicated that physical-chemical properties alone do not determine bioaccumulation in a species; fish characteristics are also important. The relationship of the bioconcentration factor (BCF) and the octanol-water partition coefficient (K{sub OW}) was examined. The correlation was weak for pesticides and poor for PCB congeners when compared to published relationships based on laboratory data.

Evaluation of an annular denuder/filter pack system to collect acidic aerosols and gases.

Abstract: A glass impactor was designed and evaluated along with an annular denude/filter pack system. The glass impactor has a 50% aerodynamic cutoff of 2.1 ..mu..m at a flow of 10 L min/sup /minus/1/ and allows a quantitative transfer of gases and fine particles to the annular denuder and filter pack components. Fine particle and gas concentrations, determined by using the glass impactor along with the annular denuder/filter pack, were in good agreement with those obtained with colocated reference samplers. Measurements of SO/sub 2/, HNO/sub 3/, and HNO/sub 2/ gases showed mean collection efficiencies of 0.993, 0.984, and 0.952, respectively, which compare well with predicted values. Additionally, it was found that artifact formation of nitrate and nitrite ions, representing about 5-10% of the concentrations of HNO/sub 3/ and HNO/sub 2/, occurs in the Na/sub 2/CO/sub 3/-coated annular denuder. Corrections for these artifacts were made with a second Na/sub 2/CO/sub 3/-coated annular denuder. The results of this pilot study suggest that the glass impactor/annular denuder/filter pack sampling system is suitable for measuring acidic aerosols and gases.

Bioconcentration and residue patterns of chlordane compounds in marine animals: invertebrates, fish, mammals, and seabirds.

Abstract: The bioconcentration and compositional patterns of chlordane compounds (CHLs: cis-chlordane, transchlordane, cis-nonachlor, trans-nonachlor, and oxychlordane) were investigated in organisms from two marine ecosystems. The bioconcentration factors (BCF: concentration in organism/concentration in seawater) of CHLs in lower trophic organisms were in between the values obtained for HCHs (a-HCH, P-HCH, and yHCH) and DDTs (p,p’-DDE and p,p’-DDT). In the case of higher trophic organisms, the scatter in the biomagnification factors (BMF: concentration in organism/concentration in food) of CHLs was found to be wider than those observed for HCHs and DDTs. Also, there were remarkable differences in CHLs composition among higher trophic organisms. For example, the percent composition of oxychlordane, which is one of the persistent metabolites of CHLs in seabirds from both areas, was higher than those of marine mammals.

DNA adsorption to soils and sediments

Abstract: Deoxyribonucleic acid (DNA) adsorption to five soils, an acid-washed sand, and a lake sediment was investigated. All DNA at environmentally relevant concentrations was adsorbed by soils containing a significant amount of montmorillonite at low to neutral pH values. Studies on the effects of DNA molecular size on adsorption to sand and a sandy soil were described by the Freundlich isotherm model (r/sup 2/ > 0.85) and indicated a direct relationship between molecular weight and adsorption.

Kinetics of trace metal complexation: role of alkaline-earth metals

Abstract: The rate of reaction of inorganic copper with the model ligand ethylenediaminetetraacetic acid (EDTA) is significantly retarded in the presence of calcium at seawater concentrations. The half-life for inorganic copper reacting with EDTA in seawater is /similar to/2 h at 10/sup /minus/7/M EDTA. This kinetic hindrance to the formation of the thermodynamically favored CuEDTA species results from several factors: (1) the preponderance of the calcium complex in the speciation of EDTA, (2) the competition of calcium and copper for reaction with any free EDTA formed by the dissociation of CaEDTA, and (3) the slow kinetics of direct attack of copper on CaEDTA compared to reaction with free or protonated EDTA species. If metal-complexing agents in natural waters behave as discrete ligands, then the reaction of a metal at strong binding sites may also be kinetically hindered at high alkaline-earth concentrations. In contrast with the reaction of EDTA, however, the rate of completion of copper by humic acid is not observably affected by high calcium concentrations.