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The nitrification process was simulated using benchtop bioreactors to gain insight into the fate of the antimicrobials triclosan (TCS) and triclocarban (TCC), as well their transformation products, during wastewater treatment. Currently, little information exists on the impact of nitrification treatment on concentrations of TCC, TCC degradation products, and TCS degradation products. Reactors were run using samples collected from a large municipal wastewater treatment plant at two pH ranges (6.5–7.5 and 8.5–9.5) for 171 h to simulate an extended hydraulic retention time (HRT). TCS was degraded under both pH conditions, with a 28.5% overall reduction in solids samples when the pH range was 6.5–7.5 and an overall reduction of 83.2% in solids samples when the pH ranged 8.5–9.5. Methyltriclosan (MeTCS) was formed in solids samples during both treatment conditions. MeTCS formed the most rapidly during the first 25 h of treatment at pH 8.5–9.5. Levels of 2,4-dichlorophenol, a TCS photolysis product, and TCC did not change over the 171 h treatment period, indicating that nitrification is not an effective treatment for reduction of these compounds. Three TCC dechlorination products and triclosan-O-sulfate were not observed at or above the limit of quantitation in any bioreactor samples.

Characterization of the soil metabolome contributes to our understanding of how soil microbial community functions, central to sustainable agriculture, are impacted by agricultural management practices. The aim of this study was to refine the Bligh-Dyer 2-phase extraction method, commonly used in soil phospholipid fatty acid analysis (PLFA), to enhance soil metabolite detection and use this refined method to look at the impact of specific crop production factors on the soil metabolome. We modified the Bligh-Dyer 2-phase extraction method through the addition of the volatile salt, 0.25 M ammonium bicarbonate, to increase the number of metabolites extracted from soil. A greenhouse pot study with three soil types and two crop species was conducted, and soil metabolites extracted using this refined Bligh-Dyer 2-phase extraction, to determine the impact of soil type and crop species treatments on the soil metabolome. Numerous amino acids, carbohydrates, TCA cycle intermediates, and fatty acids as well as the potentially inhibitory compounds ferulic acid, caffeic acid, oxalic acid, and quinic acid differed significantly with treatment. At the onset of the greenhouse pot experiment the three soil types differed significantly in metabolite composition and at the end of the 6 week experiment both soil and crop had significant impacts on the soil metabolome. Substituting the volatile salt 0.25 M ammonium bicarbonate for phosphate buffer in the Bligh-Dyer 2-phase extraction did not significantly impact PLFA analysis of the three soils. The extract was also found to be useable in lipidomic analysis. We conclude that the addition of this volatile salt to the Bligh-Dyer 2-phase extraction provided an effective method for analysis of both the soil metabolome and soil PLFA.

Since the 1950's, the broad-spectrum, organochlorine insecticide endosulfan (6,7,8, 9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepine-3-oxide) has been used on numerous crops. Due to its persistence, bioaccumulation, long-range transport, and adverse effects to human health and ecosystems, it was officially identified as a persistent organic pollutant (POP) in 2011. The last uses in the United States were phased out in 2016. Endosulfan consists of two diastereomers, α-endosulfan and β-endosulfan, and while the α-isomer exists as two asymmetrical, twist-chair enantiomers which interchange, the β-isomer is a symmetrical-chair conformation. In addition, the β-isomer was found to isomerize to the α-isomer. Gradient Temperature Raman Spectroscopy (GTRS) enables identification the molecular sites at which bending vibrational modes becomes twisting or wagging vibrational modes. Previous studies using GTRS and chemical calculations afforded evidence for specific bond movements and the irreversibility of the isomerization mechanism. However, not all of the vibrational modes observed in the spectra could be explained. Thus, new analyses of the GTRS data were conducted to examine the effects of torsional forces on the bond movement, which allowed for the identification of all the peaks. These newly-identified torsional forces provide further confirmation of the isomerization mechanism and its irreversibility. Finally, this isomerization explains why β-endosulfan is rarely detected in the atmosphere.

To better address how much groundwater contributes to the loadings of pollutants from agriculture we developed a specific dating tool for groundwater residence times. This tool is based on metolachlor ethane sulfonic acid, which is a major soil metabolite of metolachlor. The chiral forms of metolachlor ethane sulfonic acid (MESA) and the chiral forms of metolachlor were examined over a 6-year period in samples of groundwater and water from a groundwater-fed stream in a riparian buffer zone. This buffer zone bordered cropland receiving annual treatments with metolachlor. Racemic (rac) metolachlor was applied for two years in the neighboring field, and subsequently S -metolachlor was used which is enriched by 88% with the S -enantiomer. Chiral analyses of the samples showed an exponential increase in abundance of the S -enantiomeric forms for MESA as a function of time for both the first order riparian buffer stream ( R 2 = 0.80) and for groundwater within the riparian buffer ( R 2 = 0.96). However, the S -enrichment values for metolachlor were consistently high indicating different delivery mechanisms for MESA and metolachlor. A mean residence time of 3.8 years was determined for depletion of the initially-applied rac-metolachlor. This approach could be useful in dating groundwater and determining the effectiveness of conservation measures. One sentence summary A mean residence time of 3.8 years was calculated for groundwater feeding a first-order stream by plotting the timed-decay for the R -enantiomer of metolachlor ethane sulfonic acid.

Nitrogen pollution in watersheds containing significant cropland area is generally problematic. Conservation practices intended to reduce nitrate-N (NO3--N) export from watersheds are being implemented by many regions without necessary tools to assess effectiveness of abatement. A commonly used herbicide metolachlor degrades in the vadose zone of croplands to form two metabolites (metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA)) which are both highly soluble in soils. Study of metabolite fates in a first order watershed provided evidence that transport of these metabolites to stream water is highly correlated to transport of agricultural NO3--N that also forms in the cropland vadose zone. Linear models describing the relationships of stream flux of MESA and MOXA to NO3--N flux generated goodness of fit values of 0.93 and 0.81, respectively. These findings support a conclusion that both MESA and MOXA act as excellent transport analogs of NO3--N and become strongly correlated to agricultural NO3--N leaching from the cropland vadose zone. Moreover, their use as conservative tracers in agricultural watersheds can provide valuable information concerning movement and fate of agricultural nitrogen at watershed scales of observation.

A common response of plant leaves and roots to stress, biotic or abiotic, is the oxidative burst. In leaves, this results in reactive oxygen species being produced within the apoplast, the space surrounding the responding cells. A second response that occurs in the tobacco apoplast during this period is the production and accumulation of phenolic metabolites. The interaction of these redox active metabolites should have major effects on the redox potential of the apoplast and subsequently affect the outcome of the plant tissue. To begin to understand the effects of these responses on the redox potential, two induced phenolics, acetovanillone (AV) and acetosyringone (AS) were studied in vitro with peroxidase and H2O2, all of which are present in the tobacco apoplast. While both phenolics were observed to be substrates for peroxidase, AV was found to react 10x faster than AS. The oxidation of AV resulted in an increase of the redox potential to a maximum of 0.35 V. The oxidation of AS resulted in an increase to a maximum of 0.55 V. Interestingly, the redox potential was not proportional to the oxidation of either phenolic. It was found that when present together, co-oxidation occurs with the faster acting AV as a catalyst to oxidize AS. This has an immediate effect on the redox potential. The rate of AS oxidation is dependent on the AV concentration and thus so is the redox potential reaching 4.5 V. The results suggest that these phenolics could play a role in the regulation of the apoplast redox potential during the early stages of stress.

The objective of this study was to corroborate, in pepper, the response of tobacco to induce apoplast phenolics upon bacterial inoculation. Leaves of Bell peppers (Capsicum annuum), 6–8 weeks old, were inoculated with bacteria and analyzed for apoplast phenolics after different periods of incubation. Pseudomonas syringae pv. tabacci, 108 cfu ml−1, induced numerous phenolics to accumulate in the leaf apoplast after 24 h. UPLC-UV chromatograms revealed about 15 UV-peaks, some containing several components. Using this bacterial isolate, it was found that all the fully developed leaves on a single plant had a similar phenolic response based on magnitude and composition of the phenolics. Between plants, the phenolic composition was also similar, although there was more variability. The magnitude of response was proportional to the bacterial concentration between 105-108 cfu ml−1. Plants inoculated with water or P. fluorescens, a saprophyte, had a negligible response. When pepper plants were inoculated with different bacterial pathogens, P. s. pv. tomato and pv. syringae, there were differences in the magnitude and composition of the phenolics after 24 h. A time course showed that phenolic accumulation was underway by 7 h and appeared to peak by 24 h. The bacterial induction of apoplast phenolics in pepper, described here, corroborates the similar response previously described for tobacco. The preliminary characterization by UPLC-UV/MS suggests the apoplast phenolics found in pepper are structurally different from those in tobacco. However, the similar timing and location of the responses in both plants would suggest that their roles in the plant bacterial interaction are also similar. Further investigation of the redox and bioactivity properties of these apoplast phenolics is needed.

Urban streams are an integral part of the municipal water cycle and provide a point of discharge for wastewater treatment plant (WWTP) effluents, allowing additional attenuation through dilution and transformation processes, as well as a conduit for transporting contaminants to downstream water supplies. Domestic and commercial activities dispose of wastes down-the-drain, resulting in wastewater containing complex chemical mixtures that are only partially removed during treatment. A key issue associated with WWTP effluent discharge into streams is the potential to cause endocrine disruption in fish. This study provides a long-term (1999–2009) evaluation of the occurrence of alkylphenolic endocrine disrupting chemicals (EDCs) and other contaminants discharged from WWTPs into streams in the Great Lakes and Upper Mississippi River Regions (Indiana, Illinois, Michigan, Minnesota, and Ohio). The Greater Metropolitan Chicago Area Waterways, Illinois, were evaluated to determine contaminant concentrations in the major WWTP effluents and receiving streams, and assess the behavior of EDCs from their sources within the sewer collection system, through the major treatment unit processes at a WWTP, to their persistence and transport in the receiving stream. Water samples were analyzed for alkylphenolic EDCs and other contaminants, including 4-nonylphenol (NP), 4-nonylphenolpolyethoxylates (NPEO), 4-nonylphenolethoxycarboxylic acids (NPEC), 4- tert -octylphenol (OP), 4- tert -octylphenolpolyethoxylates (OPEO), bisphenol A, triclosan, ethylenediaminetetraacetic acid (EDTA), and trace elements. All of the compounds were detected in all of the WWTP effluents, with EDTA and NPEC having the greatest concentrations. The compounds also were detected in the WWTP effluent dominated rivers. Multiple fish species were collected from river and lake sites and analyzed for NP, NPEO, NPEC, OP, and OPEO. Whole-body fish tissue analysis indicated widespread occurrence of alkylphenolic compounds, with the highest concentrations occurring in streams with the greatest WWTP effluent content. Biomarkers of endocrine disruption in the fish indicated long-term exposure to estrogenic chemicals in the wastewater impacted urban waterways.

Over 50% of streams in the Chesapeake Bay watershed have been rated as poor or very poor based on the index of biological integrity. The Choptank River estuary, a Bay tributary on the eastern shore, is one such waterway, where corn and soybean production in upland areas of the watershed contribute significant loads of nutrients and sediment to streams. We adopted a novel approach utilizing the relationship between the concentration of nitrate-N and the stable, water-soluble herbicide degradation product MESA {2-[2-ethyl-N-(1-methoxypropan-2-yl)-6-methylanilino]-2-oxoethanesulfonic acid} to distinguish between dilution and denitrification effects on the stream concentration of nitrate-N in agricultural subwatersheds. The ratio of mean nitrate-N concentration/(mean MESA concentration * 1000) for 15 subwatersheds was examined as a function of percent cropland on hydric soil. This inverse relationship (R2 = 0.65, p

Nutrient inputs from urban encroachment and agricultural activities have been implicated in contributing to the environmental health decline and loss of organism diversity of South Florida ecosystems. Intensive agricultural pesticide use may also challenge these ecosystems. One possible mechanism is pesticide release to the atmosphere after application. The process is enhanced in this region due to the calcareous soils, frequent rainfall, and high humidity and temperatures. This study examined the atmospheric fate of the widely-used insecticide endosulfan. Air samples were collected over a five-year period (2001–2006) at a site within the agricultural community of Homestead, Florida and at sites located in nearby Biscayne and Everglades National Parks (NPs). Mean gas phase air concentrations of α-endosulfan were 17 ± 19 ng m−3 at Homestead, 2.3 ± 3.6 ng m−3 at Everglades NP, and 0.52 ± 0.69 ng m−3 at Biscayne NP. Endosulfan emissions from agricultural areas around Homestead appeared to influence air concentration observations at the NP sites. During an intensive sampling campaign, the highest total endosulfan concentrations at the NP sites were observed on days when air parcels were predicted to move from Homestead towards the sampling locations. The α-endosulfan fraction (α/(α + β)) was used to examine the contribution of pesticide drift versus volatilization to the overall residue level. The formulated product has an α fraction of approximately 0.7, whereas volatilization is predicted to have an α fraction of ≥0.9. The median α- fraction observed during periods of high agricultural activity at Homestead and Everglades NP was 0.84 and 0.88, respectively, and during periods of low agricultural activity the median at Homestead was 0.86, indicating contributions from drift. The median α fraction at Everglades NP was 1.0 during periods of low agricultural activity, while Biscayne NP was 1.0 year round indicating air concentrations are primarily influenced by regional volatilization.

Excess nutrients and agrochemicals from non-point sources contribute to water quality impairment in the Chesapeake Bay watershed and their loading rates are related to land use, agricultural practices, hydrology, and pollutant fate and transport processes. In this study, monthly baseflow stream samples from 15 agricultural subwatersheds of the Choptank River in Maryland USA (2005 to 2007) were characterized for nutrients, herbicides, and herbicide transformation products. High-resolution digital maps of land use and forested wetlands were derived from remote sensing imagery. Examination of landscape metrics and water quality data, partitioned according to hydrogeomorphic class, provided insight into the fate, delivery, and transport mechanisms associated with agricultural pollutants. Mean Nitrate-N concentrations (4.9 mg/L) were correlated positively with percent agriculture (R2 = 0.56) and negatively with percent forest (R2 = 0.60). Concentrations were greater (p = 0.0001) in the well-drained upland (WDU) hydrogeomorphic region than in poorly drained upland (PDU), reflecting increased denitrification and reduced agricultural land use intensity in the PDU landscape due to the prevalence of hydric soils. Atrazine and metolachlor concentrations (mean 0.29 μg/L and 0.19 μg/L) were also greater (p = 0.0001) in WDU subwatersheds than in PDU subwatersheds. Springtime herbicide concentrations exhibited a strong, positive correlation (R2 = 0.90) with percent forest in the WDU subwatersheds but not in the PDU subwatersheds. In addition, forested riparian stream buffers in the WDU were more prevalent than in the PDU where forested patches are typically not located near streams, suggesting an alternative delivery mechanism whereby volatilized herbicides are captured by the riparian forest canopy and subsequently washed off during rainfall. Orthophosphate, CIAT (6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine), CEAT (6-chloro-N-ethyl-1,3,5-triazine-2,4-diamine), and MESA (2-[(2-ethyl-6-methylphenyl) (2-methoxy-1-methylethyl)amino]-2-oxoethanesulfonic acid) were also analyzed. These findings will assist efforts in targeting implementation of conservation practices to the most environmentally-critical areas within watersheds to achieve water quality improvements in a cost-effective manner.

Triclosan (5-chloro-2-[2,4-dichloro-phenoxy]-phenol (TCS) is an antimicrobial compound that is added to a wide variety of household and personal care products. The consumer use of these products releases TCS into urban wastewater and this compound ends up in the environment when agricultural land is fertilized with wastewater biosolids. This study examines the occurrence of TCS in biosolids and its fate in biosolid-treated soils. TCS levels in biosolids generated from one repeatedly-sampled wastewater treatment plant averaged 15.6 + or - 0.6 mg kg(-1) dry wt. (mean + or - standard error) with a slight increase from 2005 to 2007. Surface soil samples were collected from several farms in northern Virginia, US that had received no biosolids, one biosolid application or multiple biosolid applications since 1992. Farm soils that received one application presented TCS concentrations between 4.1 and 4.5 ng g(-1) dry wt. when time since application was over 16 months and between 23.6 and 66.6 ng g(-1) dry wt. for farms where sampling time after application was less than a year. Our results suggest that TCS content of biosolids are rapidly dissipated (estimated half-life of 107.4 d) when applied to agricultural fields. Statistical differences were found (p

The benzoxazinoid 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) is produced by rye (Secale cereale) and may contribute to plant-parasitic nematode suppression when rye plants are incorporated as a green manure. We investigated the fate of DIBOA in soil and DIBOA’s effects on nematode reproduction. Soil in plastic bags was treated with DIBOA at concentrations ranging from 1.1 to 18 m gg �1 dry soil, and with the root-knot nematode Meloidogyne incognita. Control soils were treated with water or with 0.31% methanol, with or without nematodes. DIBOA concentrations extracted from the soil were measured at selected times for 5 consecutive days. The soil from each bag was then placed into a pot in the greenhouse, and a cucumber seedling was transplanted into each pot. Five weeks later, only the highest DIBOA concentration, 18 m gg �1 soil, reduced nematode egg numbers. At 0 h, DIBOA measured in soil ranged from 19.68 to 35.51% of the initial DIBOA concentration, and was dependent on the concentration added to the soil. DIBOA half-life was from 18 to 22 h, and very little DIBOA was present in soil after 120 h. Identified breakdown products accounted for only 4% at maximum of the initially added DIBOA. The results of our study demonstrate that high soil concentrations of DIBOA are necessary to suppress M. incognita; DIBOA may not be a major factor in nematode suppression by a rye cover crop. Published by Elsevier Ltd.

This study focuses on the differential induction of extracellular phenolic amides that accumulate in potato cell suspensions during the first few hours of the interaction between these plant cells and either bacterial pathogens or pathogen-related elicitors. Using suspension cells of Solanum tuberosum we identified 4 hydroxycinnamic acid amides that accumulate in the extracellular environment. Treatment of the suspension cells with pathovars of the plant pathogens Pseudomonas syringae or Ralstonia solanacearum or with pathogen-related elicitors changed the composition of the extracellular phenolic amides within hours and the composition differed for each treatment. Some of the phenolic amides were sensitive to oxidative stress; when suspension cells were treated with bacterial strains or elicitors that triggered an oxidative burst, the phenolics were oxidized and depleted for the duration of the burst. Other critical parameters that affected the qualitative and quantitative makeup of these phenolic amides were plant cell age and density.

Antibiotics and hormones are considered emerging environmental microcontaminants because of their potential adverse effects on ecosystems and human health. Available information on the source of these emerging contaminants in surface waters is very limited. The objectives of this study were to determine the occurrence of antibiotics and hormones in an agricultural watershed and to determine the seasonal variability of these contaminants. Water samples were collected from 15 subwatershed stations and 7 stations on the major receiving river, Choptank, Maryland, USA, over four different seasons (April, June, September and December). Antibiotics (sulfathiazole, sulfamerazine, sulfamethizole, sulfamethazine, sulfachloropyridazine, sulfamethoxazole, sulfadimethoxine, tetracycline, oxytetracycline, chlortetracycline and doxycycline) and hormones (estriol, estradiol, 17α-ethynylestradiol, estrone, testosterone and progesterone) as well as arsenic which is used as feed additive were determined in these water samples. In addition, the same antibiotics were analyzed in one set of sediment samples. This study indicated that agriculture may act as a source of antibiotic residues in the aquatic environment.

The removal of several hormones and antibiotics by nanofiltration membranes was studied in mixed solutions. The effects of solution chemistry, organic matter and salinity were investigated on the rejection of tetracycline's and sulfanamides and selected hormones and their adsorption on membranes. Tetracyclines were observed to have a high adsorptive affinity for the membrane. Almost 80% of chlorotetracycline was adsorbed on the membrane surface compared with 50% for doxcycline while the adsorption rates for hormones were lower than those obtained for tetracyclines. Addition of calcium, organic matter and salinity had an influence on the rejections. Rejection of sulfanamides was low compared to hormones and tetracyclines. Addition of antibiotics to hormone solution increased the hormone rejections while almost complete rejections were observed for tetracyclines.

Various chemical and biological measures were determined in carp ( Cyprinus carpio ) sampled from seven sites along the Cuyahoga River, Ohio; from the relatively pristine headwaters to the lower portion heavily polluted from various industrial, urban and wastewater treatment plants (WWTP). Levels of nonylphenol (NP), nonylphenol ethoxylates (NPEs; NP1EO, NP2EO) and total NPEs (NP plus the NPEs) in fish increased in a downstream direction, with maximal values observed below the discharge of the Akron WWTP. In female fish there were no significant differences between sites in GSI or levels of vitellogenin (VTG) and 17β-estradiol (E2). However, differences were observed between sites using measures of 11-ketotestosterone (11-KT) and the ratio E2/11-KT. In male fish the highest levels of VTG were observed downstream of the Akron WWTP and a significant correlation ( r = 85%) between levels of NP and VTG was demonstrated. No site differences were observed in the measures of GSI, E2, 11-KT or the E2/11-KT ratio in male fish. These data suggest that endocrine active chemicals, such as, NP and NPEs are impacting fish downstream of the Akron WWTP; however, further work is warranted to separate linkages to other possible chemical factors in the water.

The fate of antibiotic residues in the manure of treated animals is of considerable concern because of the potential development of antibiotic-resistant bacteria in the environment and because of the effect of these residues on manure treatment systems. The objective of this study was to determine the fate and effect of oxytetracycline (OTC) during the anaerobic digestion of manure from medicated calves. Five beef calves were medicated for 5 days with 22 mg/kg/day of OTC. Manure samples collected from calves prior to and after medication were diluted five-fold with water, loaded into replicate 1.2 l anaerobic digesters and incubated at 35 °C. OTC levels in the manure slurry decreased from 9.8 ± 0.1 to 4.1 ± 0.1 mg/l in 64 days (59% removal) yielding a calculated value half-life for OTC of 56 days. Levels of the OTC epimer 4-epi-oxytetracycline increased gradually from 0.55 ± 0.03 mg/l at the start of experiment to 1.3 ± 0.1 mg/l on day 27 and then decreased to 0.84 ± 0.04 mg/l on day 64. Levels of two other OTC metabolites (α-apo-oxytetracycline and β-apo-oxytetracycline) decreased or remained unchanged during the anaerobic digestion process. Cumulative biogas production was 27% lower from digesters containing manure from medicated calves relative to that from digesters containing unmedicated manure. However, the presence of OTC did not show other negative effects on process stability as there were no significant differences in biogas methane content or in reductions of volatile solids and soluble organic carbon.

This study focuses on the transient and complex nature of phenolics that accumulate in the extracellular environment of plant suspension cells during the first few hours of the interaction between these plant cells and bacterial pathogens. Using suspension cells of Nicotiana tabacum we identified four acetophenones and four hydroxycinnamic acid amides that accumulate in this extracellular environment. Treatment of the suspension cells with isolates of the plant pathogen Pseudomonas syringae or heat-killed bacteria increased elicitation of extracellular phenolics and changed the composition of the compounds that accumulated. These phenolics were sensitive to oxidative stress; when suspension cells were treated with bacterial strains or elicitors that triggered an oxidative burst, these phenolics were oxidized and depleted for the duration of the burst. The qualitative and quantitative makeup of phenolics produced by N. tabacum suspensions was also affected by plant cell age and density. To our knowledge, this is the first study that closely follows the kinetics of individual extracellular phenolic compounds and the concurrent oxidative stress during the first few hours of a plant–bacterial interaction. Published by Elsevier Ltd.

Polybrominated diphenyl ethers (PBDEs) were identified in fish collected from the Detroit River, MI and Des Plaines Rivers, IL. In the Detroit River fish, carp and large mouth bass, the congener patterns were dominated by the 2,2',4,4'-tetrabromo (BDE-47) congener, however, in Des Plaines River carp the dominant isomers were the heptabromo congeners BDE-181 and BDE-183 and lesser amounts of another heptabromo congener, BDE-190, and two hexabromo congeners, BDE-154 and BDE-153. Three possible sources exist for these less-commonly identified PBDE congeners: (a) waste discharge from manufacturing or discarded products near the river, (b) public owned treatment work (POTW) effluents which constitute more than 75% of the flow in the Des Plaines River, (c) or formation of these congeners by debromination of in-place deposits of decabromodiphenyl ether. Average concentration totals (sum of concentrations for seven of the dominant PBDE congeners) were similar on a wet weight bases for the carp (5.39 ng/g wet weight) and large mouth bass (5.25 ng/g) in the Detroit River samples; however, the bass were significantly higher, p = 0.01, when compared on a lipid basis (bass--163 ng/g vs. carp--40.5 ng/g lipid weight). Some of the PBDE congeners were positively correlated with increasing lipid levels in both fish species. Average total PBDE concentrations in the carp from the Des Plaines River (12.48 ng/g wet weight) were significantly higher, p = 0.01, than in carp from the Detroit River. The residues were isolated using standard organochlorine methods for fish and analyzed using gas chromatography/mass spectrometry-negative chemical ionization methods.

Coincident samples of arctic marine fog and air were found to contain the following pesticides, chlorpyril chlorothalonil, metolachlor, terbufos and trifluralin. The levels of the different pesticides in the fog ranged from 0.08 to 12 ng/L and for the air from < 0.1 to 5.0 pg/m3. Field derived air-water partition coefficients (Henry's law contstants-HLCs) were calculated from the paired air and water concentrations for chlorpyrifos and trifluralin. Comparisons of the field measured HLC values with laboratory determined HLCs (based on distilled water and on the fogwater itself) indicated that the pesticides were enriched in the field collected fogwater. The enrichments apwear to be predominantly caused by surface interaction processes. Concentrations of the pesticides in the fog were much higher than adjoining compartments of snow, ice, air, water or microlayer. Exchanges at these interfaces may be a common occurrence in the Arctic especially since fogs are common over much of the area.

Investigation of currently-used pesticides (triazines, acetanilides, organophosphates and organochlorines) was carried out in the Bering and Chukchi marine ecosystems in the summer of 1993. Chlorpyrifos and trace levels of endosulphan were the most frequently identified contaminants in seawater, chlorpyrifos and atrazine were found in marine ice, and chlorothalonil and trifluralin were found in surface microlayer samples. Concentrations of chlorpyrifos were highest (170 ng l−1) in marine ice and higher in seawater (19–67 ng l−1) at locations which were closest to the ice edge. Endosulphan was found as a widely distributed currently used pesticide in the polar atmosphere. The greatest concentration of any one single agrochemical was trifluralin (1.15 μg l−1) in a Bristol Bay surface microlayer sample. Arctic marine fog was sampled and for the first time, several currently-used pesticides (chlorpyrifos, trifluralin, metolachlor, chlorothalonil, terbufos and endosulphan) were detected at concentrations several times higher than in adjacent waters or ice.

An electron capture negative ion mass spectrometric method for quantitative determination of chlorobornanes was tested on selected samples from an arctic marine food chain. The method provided sufficient sensitivity to detect residues down to 0.3 ppb. Detailed area counts at prescribed mass scans were collected and processed for two selected samples, a fish and a neuston sample. Total chlorobornane concentrations were, 1.6 ng/g for the neuston and 12.8 ng/g for the pollack. Chlorine homologue class (Cl 6 to Cl 10 ) concentrations for each sample were determined. Relative homologue amounts linked the neuston to an atmospheric input since it had highest concentrations of Cl 6 , which is more prevalent in air, while the fish had a higher relative levels of Cl 8 and Cl 9&10 homologues indicative of the tendency for these more lipophilic homologues to concentrate in fish lipids.

Composite, nearshore, whole fish samples of selected species, collected in fall 1983 from 13 Lake Michigan tributaries and Grand Traverse Bay, were analyzed for a wide range of pesticides and priority pollutants using gas chromatography-mass spectrometry. This study was carried out to identify existing source areas for known and previously unrecognized toxic substances. Our strategy was to analyze those resident fish with the highest likely levels of contaminants. All fish analyzed (eight species from southern Michigan to the upper peninsula) exceeded the 2 mg/kg FDA action levels for PCBs, while 50% of the samples exceeded the DDTr IJC objective of 1 mg/kg. St. Joseph River common carp (Cyprinus carpio) carried the heaviest contaminant burden of all fish examined for PCBs (27.6 mg/kg), DDTr (10.2 kg/mg), and toxaphene (3.3 mg/kg); chlordane levels (0.85 mg/kg) were second highest to those in Kalamazoo River common carp (0.87 mg/kg). Concentrations of PCBs, toxaphene, DDT, DDE, and other pesticides were higher in bottom-feeding fish, such as common carp, than in top predators, e.g., northern pike (Esox lucius). Bottom feeders are relatively fatty fish, and live and feed near contaminated sediments, which increases their potential to bioaccumulate fat-soluble contaminants. Pesticides were also present in elevated concentrations in fish from sites with higher industrial and agricultural development.

PCB residues were measured in samples of Cladophora, Ulothrix , net plankton, water, and fish collected in the Harbor Beach area of Lake Huron. The average concentrations of total PCB in each of the sample groups were as follows: water - 0.154 ng/g; Cladophora - 92 ng/g; Ulothrix - 126 ng/g; net plankton - 1,651 ng/g; and fish - 40 to 4,400 ng/g. The PCB patterns in the samples were found to match a mixture of Aroclo6r 1242 and 1254. Aroclor 1242 represented about 60% of the mixture in all the samples except the fish, where Aroclor 1254 represented about 75% of the total PCB measured. The accumulation factors observed in the progression from Cladophora to net plankton to fish were 1:15:30; these were similar to the concentration factors (1:14:44) developed on these ecosystem compartments in Lake Ontario during the 1972 IFYGL program.

The processes of exchange of PCBs and related organics at the surface of large bodies of water such as the Great Lakes are unavoidably linked to the unique properties of surface films. We have observed a 3 to 8 fold enrichment of PCB over underlying water in surface film samples taken from Lake Michigan with a Garrett screen sampler. The particle association of the PCBs was highest in the microlayer, averaging 50% compared to 20% on particles in the subsurface water and less than 5% in the air. The PCBs in the samples were identified as Aroclor 1254 and Aroclor 1242. The percentage composition of the two Aroclors varied between the air and the water as follows: the air was 30.2% Aroclor 1254 and the water (microlayer plus subsurface) was 57.6% Aroclor 1254.

Part I of this series examined the chemical and thermodynamic principles underlying the solubility and partitioning characteristics of non-electrolyte organic compounds in aqueous systems. It further considered those concepts which interrelate solubility and partitioning phenomena with retentive behavior in reverse phase liquid chromatography. Conceptual and predictive models which intercorrelate solubility, octanol/water partitioning, and reverse phase retention times were developed. Part II of the seres evaluates the relative predictive abilities of these models for a wide range of different classes of organic pollutants. The results reveal that the reverse phase liquid chromatography models developed in Part I provide good estimates of octanol/water coefficients and aqueous solubilities from experimentally determined chromatographic retention times. Models structured to predict aqueous solubilities from octanol/water partition coefficient data were also found to provide reasonable estimates, but require as input physical and chemical parameters which are not readily accessible.

The top 280 ~m of water from Lake Michigan was studied in order to determine the types of particles and organisms present in the surface microlayer. The microlayer was sampled by dipping an aluminum screen into the water horizontal to the surface at stations located in Southern and Northern Lake Michigan. Surface microlayer and corresponding subsurface samples were collected in April and July, 1980.