Application of preparative capillary gas chromatography (pcGC), automated structure generation and mutagenicity prediction to improve effect-directed analysis of genotoxicants in a contaminated groundwater

Background, aim and scope  

The importance of groundwater for human life cannot be overemphasised. Besides fulfilling essential ecological functions, it is a major source of drinking water. However, in the industrial area of Bitterfeld, it is contaminated with a multitude of harmful chemicals, including genotoxicants. Therefore, recently developed methodologies including preparative capillary gas chromatography (pcGC), MOLGEN-MS structure generation and mutagenicity prediction were applied within effect-directed analysis (EDA) to reduce sample complexity and to identify candidate mutagens in the samples. A major focus was put on the added value of these tools compared to conventional EDA combining reversed-phase liquid chromatography (RP-LC) followed by GC/MS analysis and MS library search.     

Development of GC capillary column for isomer-specific separation of toxic isomer of PCDDs and PCDFs in environmental samples

Analysis of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) has been performed using gas chromatography mass spectrometry (GC-MS). Analysis of the most toxic isomers, in particular, 2,3,7,8-substituted PCDD/PCDF in the presence of other isomers requires a special isomer specific capillary column or high performance liquid chromatography (HPLC) fractionation prior to GC-MS analysis. Commercially available long (>50 m) polar columns can separate 2,3,7,8-TCDD from other tetra isomers. However, those columns are not satisfactory for the analyses of total PCDD/PCDF in the environmental samples. Gas chromatography -high resolution mass spectrometry (GC-HRMS) and GC-MS/MS techniques are not helpful in the analysis of 2,3,7,8-TCDD unless it is separated from the other tetra isomers. The analysis of 2,3,7,8-TCDD and total PCDD and PCDF in a single GC-MS run can ease the laborious techniques presently used. In this study we have developed a new stationary phase for the GC capillary column. The capillary column developed using this new stationary phase showed unsurpassed selectivity for the separation of 2,3,7,8-TCDD from other tetra isomers. There are several advantages of the newly developed GC capillary column.     

A new approach for the fractionation of water-soluble organic carbon in atmospheric aerosols and cloud drops

A novel approach is described for the fractionation of water-soluble organic carbon (WSOC) in atmospheric aerosols and cloud drops. The method is based on the preliminary adsorption of the sample, acidified at pH 2, on a polymeric styrene-divinylbenzene resin (XAD-2) and subsequent elution with a series of solvents, which leads to the fractionation of the sample into three classes of compounds. The method was set up using synthetic mixtures of organic compounds and then applied to selected samples of atmospheric aerosols and cloud drops. All samples and collected fractions were analysed using size exclusion chromatography (SEC). This method proved particularly useful both in providing information on the organic content of the samples and for the characterisation of the macromolecular compounds (MMCs) in the samples. Synthetic samples were prepared using humic, fulvic and tannic acid to simulate naturally occurring MMCs. In the first fraction, eluted with HCl, only the most soluble organic compounds (oxalic acid, formic acid and acetic acid) were collected. In the second fraction, eluted with methanol, the major part of the organic material was collected together with the more hydrophilic constituents of the humic substances. In the third fraction, it was possible to separately recover the more hydrophobic component of the humic substances. A large number of atmospheric samples (fog, aerosol, cloud) were then analysed using SEC. Most of these samples evidenced a noteworthy chromatogram at 254 nm. Moreover, the chromatographic area evidenced a clear linear correlation with the total organic carbon (TOC) values. The fractionation method on XAD-2 was finally applied to selected atmospheric samples, yielding three classes of organic compounds. In each sample, a non-negligible amount of compounds with dimensional and chemical properties similar to humic substances were collected in the third fraction. The carbon content in this latter fraction was estimated both by TOC and by means of the correlation between TOC and SEC area.     

Identification of the dimethylbenzyl mercapturic acid in urine of rats administered with 1,2,4-trimethylbenzene

A study was undertaken of the mercapturic acid metabolism of 1,2,4-trimethylbenzene in the rat. Of three regioisomeric dimethylbenzyl mercapturic acids, i.e. 2,4-, 2,5- and 3,4-dimethylbenzyl isomers, the third isomer was not found in the urinary mercapturic acid isolated by preparative HPLC, from the comparison of NMR spectrum of the isolate with those of authentic specimens. The urinary mercapturate was then assigned to 2,4- and/or 2,5-dimethylbenzyl isomers. The excretion rate of the mercapturic acid was 14-20% of dose as 2,4-dimethylbenzyl isomer.     

Distribution of hexachlorocyclohexane isomers in soil samples from a small scale industrial area of Lucknow, North India, associated with lindane production

Concentrations of hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH, and delta-HCH) were studied in soils samples collected from a small scale industrial unit of Lucknow associated with lindane production. All four isomers were detected from ten sites and the total HCH isomers in the analyzed samples varied from 53 to 99mgkg(-1). Cluster analysis was performed to group the soil sites in terms of their HCH contamination level. Low alpha/gamma HCH ratios were found and they indicate recent input of HCH. There is an urgent need for the on-site remediation of these contaminated sites in order to prevent the long-term environmental pollution.     

Separation of non-ortho polychlorinated biphenyl congeners on pre-packed carbon tubes. Application to analysis in sewage sludge and soil samples

The analysis of planar (non-ortho) polychlorinated biphenyls (PCB) by HRGC-ECD or HRGC-HRMS requires a fractionation step to avoid the interferences of the bulk of PCB, usually in much higher concentration than the planar ones. In this paper, a new method, based on the fractionation of PCB on SPE commercial tubes pre-packed with Carbopack B, has been developed. After the extract has been applied on the stationary phase, the bulk of PCD are eluted with 15 ml of hexane (fraction I), mono-ortho PCB with 20 ml of hexane/toluene 99:1 (fraction II) and planar PCB with 20 ml of toluene (fraction III) in a station under vacuum. The method has been validated: accuracy (expressed as recovery in %) is >70% and precision (expressed as % RSD) is <20% considering changes of day, analyst and batch of tubes. The method is linear in the range studied. Other advantages are that the method is simple, rapid and it can be easily automated. The application of this separation to the determination of planar PCB in fly-ash extracts from an intercalibration exercise and to sewage sludge, sediment and soil samples has been successful. In addition, this method removes hydrocarbons from the planar PCB fraction and allows its concentration to very small volumes.     

Occurrence and distribution of hexachlorocyclohexane isomers in vegetation samples from a contaminated area

The occurrence and distribution of four major hexachlorocyclohexane (HCH) isomers (alpha-, beta-, gamma- and delta-) were studied in vegetation samples of a highly contaminated area close to a small-scale industrial belt in Lucknow (North India). Eight species of plants were collected at different points of the contaminated area and different parts of the plants were separated in order to study the difference in uptake and accumulation. The samples were extracted by matrix solid-phase dispersion (MSPD) extraction and finally determined by a gas-chromatograph equipped with (63)Ni electron capture detector (ECD). HCH isomers were present in almost all samples and the concentration of total HCH in the plant sample analyzed varied between 13 and 44 mg kg(-1), being the main isomer of beta-HCH (8-22 mg kg(-1)). Lindane (gamma-HCH) was present in all samples (1-9 mg kg(-1)). Solanum torvum Sw., and Erianthus munja shows the highest and lowest capacity for accumulation of HCH, respectively with a significant difference at p<0.01 level. The highest concentration of HCH residue in root samples indicates the most likely mechanism of HCH accumulation in these plants was sorption of soil HCH on roots. Solanum torvum Sw., and Withania somnifera (L.) Dunal could accumulate considerable levels of HCH isomers (44 and 34 mg kg(-1), respectively). The results reflect the importance of plants in monitoring purposes and their potential for phytoremediation of HCH contaminated soils.     

Microbial in situ degradation of aromatic hydrocarbons in a contaminated aquifer monitored by carbon isotope fractionation

We present an approach for characterizing in situ microbial degradation using the 13C/12C isotope fractionation of contaminants as an indicator of biodegradation. The 13C/12C isotope fractionation of aromatic hydrocarbons was studied in anoxic laboratory soil percolation columns with toluene or o-xylene as the sole carbon and electron source, and sulfate as electron acceptor. After approximately 2 months' of incubation, the soil microbial community degraded 32 mg toluene l(-1) and 44 mg o-xylene l(-1) to less than 0.05 mg l(-1), generating a stable concentration gradient in the column. The 13C/12C isotope ratio in the residual non-degraded fraction of toluene and o-xylene increased significantly, corresponding to isotope fractionation factors (alphaC) of 1.0015 and 1.0011, respectively. When the extent of biodegradation in the soil column was calculated based on the measured isotope ratios (R(t)) and an isotope fractionation factor (alphaC=1.0017) obtained from a sulfate-reducing batch culture the theoretical residual substrate concentrations (C(t)) matched the measured toluene concentrations in the column. This indicated that a calculation of biodegradation based on isotope fractionation could work in systems like soil columns. In a field study, a polluted, anoxic aquifer was analyzed for BTEX and PAH contaminants. These compounds were found to exhibit a significant concentration gradient along an 800-m groundwater flow path downstream of the source of contamination. A distinct increase in the carbon isotope ratio (delta13C) was observed for the residual non-degraded toluene (7.2 per thousand ), o-xylene (8.1 per thousand ) and naphthalene fractions (1.2 per thousand ). Based on the isotope values and the laboratory-derived isotope fractionation factors for toluene and o-xylene, the extent to which the residual substrate fraction in the monitoring wells had been degraded by microorganisms was calculated. The results revealed significant biodegradation along the groundwater flow path. In the wells at the end of the plume, the bioavailable toluene and o-xylene fractions had been almost completely reduced by in situ microbial degradation. Although indane and indene showed decreasing concentrations downstream of the groundwater flow path, suggesting microbial degradation, their carbon isotope ratios remained constant. As the physical properties of these compounds are similar to those of BTEX compounds, the constant isotope values of indane and indene indicated that microbial degradation did not lead to isotope fractionation of all aromatic hydrocarbons. In addition, physical interaction with the aquifer material during the groundwater passage did not significantly alter the carbon isotope composition of aromatic hydrocarbons.     

Separation of PCBs and PAHs in sediment samples using silica gel fractionation chromatography

The aim of this research is to develop a silica gel fractionation procedure for sediment sample extracts, which separates polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) into two groups, while simultaneously eliminating most interfering substances for subsequent instrumental analysis. This is achieved by optimizing the fraction cut-off volume of eluting solvent and the deactivation level of the silica gel. Using fully activated silica gel and cutting off PCB collection after passing 60-65 ml eluting solvent (pentane or hexane) through the column resulted in satisfactory separation of PCBs and PAHs. This procedure tends to have a higher reliability for PCBs and PAHs with higher molecular mass. This approach deviates only slightly from the standard methods of the USEPA, and it is less expensive due to reduced sample pre-treatment time and solvent consumption.     

Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH=7) were loaded with nickel and cobalt in adsorption experiments (monometal and competitive conditions). The combination of sequential extraction with the sorption isotherm analysis allowed the assessment of the sorption capacity of individual fractions present in the anaerobic granular sludges. The operational fractionation of the sorbed heavy metals was determined using a modified Tessier sequential extraction procedure. The sorption characteristics of each extracted fraction (exchangeable, carbonates, organic matter/sulfides and residual fractions) fitted well to the Langmuir model. The organic matter/sulfides fraction showed the highest affinity for cobalt and nickel in both sludges investigated compared to the other operationally defined fractions. The presence of iron negatively affected cobalt and nickel accumulation in this organic matter/sulfides fraction. The trace metals-iron sulfide interactions are likely to be the key process in controlling the distribution of cobalt and nickel during sorption onto non-fed methanogenic granules due to the high affinity of iron sulfides towards the metals studied.     

Variation of zinc and copper in metallothionein-like protein in killifish (Oryzias latipes) exposed to cadmium

Killifish (Oryzias latipes) were exposed for 0, 24, 48 and 168 hours to cadmium solution. The hepatic cytoplasm was fractionated by using Sephadex G-75 and the content of zinc, copper and cadmium in the fractions was measured. Cadmium content in the metallothionein fraction increased with increase of exposure time. Zinc content in the metallothionein fraction was reduced at early exposure time and increased after prolonged exposure. Copper content in the metallothionein fraction was unchanged. It is shown that zinc bound to thionein in the liver is partially replaced by cadmium and that at least two isomers of metallothionein occur in this fish.     

Enantioselective effects of alpha-hexachlorocyclohexane (HCH) isomers on androgen receptor activity in vitro

Alpha-hexachlorocyclohexane (alpha-HCH), a part of the HCH pesticide mixture, is one of the most widespread persistent organic pollutants. Interestingly, only limited number of studies addressed the toxicity of alpha-HCH and the effects of its individual optical isomers have not been investigated in detail. In the present study we separated two alpha-HCH enantiomers by preparative HPLC and studied their activities towards androgen receptor (AR) using the MDA-kb2 cell line stably transfected with the luciferase reporter gene under the control of AR. There was no direct effect of alpha-HCH on AR but both isomers significantly suppressed the activity of AR in co-exposure with the natural ligand dihydrotestosterone in a concentration-dependent manner. One of the enantiomers appeared to be more active at lower concentration, which was also supported by the molecular modeling calculations with AR that showed a slight difference in estimated free energy of binding and inhibition constant between two enantiomers. Although studies with other pesticides demonstrated strong enantioselective differences in toxicity, the present research shows rather minor differences in modulations of AR by both alpha-HCH enantiomers. For the first time, enantioselective effects of alpha-HCH were demonstrated and the results suggest interaction with multiple regulatory events controlling the AR activity. Full elucidation of the toxicity mechanism will require further research.     

Large PAHs detected in fine particulate matter emitted from light-duty gasoline vehicles

Emission factors of large PAHs with 6–8 aromatic rings with molecular weights (MW) of 300–374 were measured from 16 light-duty gasoline-powered vehicles (LDGV) and one heavy-duty diesel-powered vehicle (HDDV) operated under realistic driving conditions. LDGVs emitted PAH isomers of MW 302, 326, 350, and 374, while the HDDV did not emit these compounds. This suggests that large PAHs may be useful tracers for the source apportionment of gasoline-powered motor vehicle exhaust in the atmosphere. Emission rates of MW 302, 326, and 350 isomers from LDGVs equipped with three-way catalysts (TWCs) ranged from 2 to 10 (μg L⁻¹ fuel burned), while emissions from LDGVs classified as low emission vehicles (LEVs) were almost a factor of 10 lower. MW 374 PAH isomers were not quantified due to the lack of a quantification-grade standard. The reduced emissions associated with the LEVs are likely attributable to improved vapor recovery during the “cold-start” phase of the Federal Test Procedure (FTP) driving cycle before the catalyst reaches operating temperature. Approximately 2 (μg g⁻¹ PM) of MW 326 and 350 PAH isomer groups were found in the National Institute of Standards and Technology standard reference material (SRM)#1649 (Urban Dust). The pattern of the MW 302, 326, and 350 isomers detected in SRM#1649 qualitatively matched the ratio of these compounds detected in the exhaust of TWC LDGVs suggesting that each gram of Urban Dust SRM contained 5–10 mg of PM originally emitted from gasoline-powered motor vehicles.Large PAHs made up 24% of the total LEV PAH emissions and 39% of the TWC PAH emissions released from gasoline-powered motor vehicles. Recent studies have shown certain large PAH isomers have greater toxicity than benzo[a]pyrene. Even though the specific toxicity measurements on PAHs with MW >302 have yet to be performed, the detection of significant amounts of MW 326 and 350 PAHs in motor vehicle exhaust in the current study suggests that these compounds may pose a significant public health risk.     

Ultraviolet disinfection of fecal coliform in municipal wastewater: effects of particle size.

Suspended solids interfere with the efficiency of disinfection using UV radiation by decreasing the rate of disinfection and inducing tailing. However, conventional measures of solids (total suspended solids, turbidity, and UV transmittance) do not adequately predict the presence or degree of these effects. Bacteria and viruses can become associated with particles in wastewater. A fractionation technique was developed to separate particle-associated bacteria into three fractions, based on particle size. The results show that the degree to which particles interfere with UV disinfection efficiency is dependent on particle size. The small size fraction (< 5 microm) consistently produced a statistically significant faster disinfection rate than the large fraction (> 20 microm), with the unfiltered sample and the medium fraction (particles > 5 microm, but < 20 microm) between the two extremes. Tailing also was observed only in the large fraction. Correlations between the disinfection rate constant and the percentage of large fraction bacteria of a sample were good.     

Effect of Fractionation and Pyrolysis on Fuel Properties of Poultry Litter

Abstract

Raw poultry litter has certain drawbacks for energy production such as high ash and moisture content, a corrosive nature, and low heating values. A combined solution to utilization of raw poultry litter may involve fractionation and pyrolysis. Fractionation divides poultry litter into a fine, nutrient-rich fraction and a coarse, carbon-dense fraction. Pyrolysis of the coarse fraction would remove the corrosive volatiles as bio-oil, leaving clean char. This paper presents the effect of fractionation and pyrolysis process parameters on the calorific value of char and on the characterization of bio-oil. Poultry litter samples collected from three commercial poultry farms were divided into 10 treatments that included 2 controls (raw poultry litter and its coarse fraction having particle size greater than 0.85 mm) and 8 other treatments that were combinations of three factors: type (raw poultry litter or its coarse fraction), heating rate (30 or 10 °C/min), and pyrolysis temperature (300 or 500 °C). After the screening process, the poultry litter samples were dried and pyrolyzed in a batch reactor under nitrogen atmosphere and char and condensate yields were recorded. The condensate was separated into three fractions on the basis of their density: heavy, medium, and light phase. Calorific value and proximate and nutrient analysis were performed for char, condensate, and feedstock. Results show that the char with the highest calorific value (17.39 ± 1.37 MJ/kg) was made from the coarse fraction at 300 °C, which captured 68.71 ± 9.37% of the feedstock energy. The char produced at 300 °C had 42 ± 11 mg/kg arsenic content but no mercury. Almost all of the Al, Ca, Fe, K, Mg, Na, and P remained in the char. The pyrolysis process reduced ammoniacal-nitrogen (NH₄-N) in char by 99.14 ± 0.47% and nitrate-nitrogen (NO₃-N) by 95.79 ± 5.45% at 500 °C.     

Separation, synthesis and estrogenic activity of 4-nonylphenols: two sets of new diastereomeric isomers in a commercial mixture

Two sets of new diastereomeric 4-nonylphenol (NP) isomers [4-(3,4-dimethylheptan-4-yl)phenol (344NP, NP-J, L) and 4-(3,4-dimethylheptan-3-yl)phenol (343NP, NP-K, P)] were separated from a commercial NP mixture. The mixture of these diastereomers was synthesized at the same time by a single Friedel-Crafts reaction of 3,4-dimethyl-4-heptanol and phenol, and the mixture was separated into individual NPs by HPLC equipped with Hypercarb column. For the first time, in this study the stereostructure-estrogenic activity relationship of NP diastereomers was investigated. The NP isomers (NP-L and NP-P) having the beta-methyl group over the benzene ring were found to be 2-4 times more estrogenic than their diastereomers (NP-J and NP-K). In the case of the other set of diastereomer [4-(3,5-dimethylheptan-3-yl)phenol, (353NP, NP-E, G)] containing gamma-methyl group in the molecule, the gamma-methyl proton signal (delta 0.49) in the more estrogenic isomer (NP-G) also appeared in a higher field than the corresponding methyl signal (delta 0.76) of the less estrogenic isomer (NP-E).     

Dissipation, half-lives, and mass spectrometric identification of endosulfan isomers and the sulfate metabolite on three field-grown vegetables

Endosulfan 3 EC, a mixture of α- and β-stereo isomers, was sprayed on field-grown pepper, melon, and sweet potato plants at the recommended rate of 0.44 kg A.I. acre(-1). Plant tissue samples (leaves, fruits, or edible roots) were collected 1 h to 30 days following spraying and analyzed for endosulfan isomers (α- and β-isomers). Analysis of samples was accomplished using a gas chromatograph (GC) equipped with a mass detector in total ion mode. The results indicated the formation of endosulfan sulfate as the major metabolite of endosulfan sulfite and the relatively higher persistence of the β-isomers as compared to the α-isomer. The initial total residues (α- and β-isomers plus endosulfan sulfate) were higher on leaves than on fruits. On pepper and melon fruits, the α-isomer, which is the more toxic to mammals, dissipated faster (T(1/2) = 1.22 and 0.95 d, respectively) than the less toxic β-isomer (T(1/2) = 3.0 and 2.5 d, respectively). These results confirm the greater loss of the α-isomer compared to the β-isomer, which can ultimately impact endosulfan dissipation in the environment. Additionally, the higher initial residues of endosulfan on pepper and sweet potato leaves should be considered of great importance for timing field operations and the safe entry of harvesters due to the high mammalian toxicity of endosulfan.     

Distribution, fate and formation of non-extractable residues of a nonylphenol isomer in soil with special emphasis on soil derived organo-clay complexes

Anthropogenic contaminants like nonylphenols (NP) are added to soil, for instance if sewage-sludge is used as fertilizer in agriculture. A commercial mixture of NP consists of more than 20 isomers. For our study, we used one of the predominate isomers of NP mixtures, 4-(3,5-dimethylhept-3-yl)phenol, as a representative compound. The aim was to investigate the fate and distribution of the isomer within soil and soil derived organo-clay complexes. Therefore, (14)C- and (13)C-labeled NP was added to soil samples and incubated up to 180 days. Mineralization was measured and soil samples were fractionated into sand, silt and clay; the clay fraction was further separated in humic acids, fulvic acids and humin. The organo-clay complexes pre-incubated for 90 or 180 days were re-incubated with fresh soil for 180 days, to study the potential of re-mobilization of incorporated residues. The predominate incorporation sites of the nonylphenol isomer in soil were the organo-clay complexes. After 180 days of incubation, 22 % of the applied (14)C was mineralized. The bioavailable, water extractable portion was low (9 % of applied (14)C) and remained constant during the entire incubation period, which could be explained by an incorporation/release equilibrium. Separation of organo-clay complexes, after extraction with solvents to release weakly incorporated, bioaccessible portions, showed that non-extractable residues (NER) were preferentially located in the humic acid fraction, which was regarded as an effect of the chemical composition of this fraction. Generally, 27 % of applied (14)C was incorporated into organo-clay complexes as NER, whereas 9 % of applied (14)C was bioaccessible after 180 days of incubation. The re-mobilization experiments showed on the one hand, a decrease of the bioavailability of the nonylphenol residues due to stronger incorporation, when the pre-incubation period was increased from 90 to 180 days. On the other hand, a shift of these residues from the clay fraction to other soil fractions was observed, implying a dynamic behavior of incorporated residues, which may result in bioaccessibility of the NER of nonylphenol.     

Identification of petrogenic contamination in recent sediments by HPLC monitoring of aromatic components: A preliminary investigation

Separation of neutral extracts from sediments and oils into aliphatic and aromatic fractions by simple fractionation techniques may not be sufficiently accurate for complete resolution of these hydrocarbon classes. In particular, the profiles of unresolved complex mixture (UCM) from GC analysis can be significantly affected by the fractionation method employed, which can have implications for the assessment of levels and sources of petrogenic pollution in Recent sediments. Results obtained from a number of sediment extracts suggest that screening of the aromatic UCM by normal phase HPLC may provide a rapid technique for assessing the relative levels of petrogenic contamination in such sediments. HPLC sub-fractionation of aromatic components and subsequent GC analysis resulted in varying UCM profiles for each fraction, suggesting that HPLC fractionation may provide a means to study the composition of the aromatic UCM.     

Source and transport of tricresyl phosphate (TCP) isomers in Kurose river basin

Atmospheric tricresyl phosphate (TCP) isomers in Kurose river basin were determined. The concentrations of o-TCP and m-TCP were 0.13 and 0.09 ng m⁻³, respectively, while p-TCP was scarcely detected. Exhaust gases from motorcycles and automobiles were main sources for TCP isomers in the atmosphere. Exhaust gas from incinerator also contributes to atmospheric concentration of TCP isomers. Most of the TCP isomers could be estimated to be sorbed to particles, due to their low vapor pressures. The concentrations of TCP isomers were relatively high in soils collected from an open storage yard of waste PVC and near the highway and greenhouse of agricultural film. On the other hand, the concentrations were negligibly small in soil collected from the forest except for the silt-clay fraction in the soil. Dry deposition fluxes of o-TCP and m-TCP from the atmosphere was 0.2 and 0.04 μg m⁻² d⁻¹, respectively. Wet deposition flux of TCP isomers during one rainfall exceeded occasionally the dry deposition flux for two weeks. TCP isomers accumulated in soil were discharged into river by precipitation event. Their concentrations increased with an increase in river flow, characteristic of a non-point source of TCP isomers.