Occurrence of the herbicide glyphosate and its metabolite AMPA in surface waters in Switzerland determined with on-line solid phase extraction LC-MS/MS.

Glyphosate is currently one of the most important herbicides worldwide. Its unique properties provide for a wide range of uses in agriculture but also in non-agricultural areas. At the same time, its zwitterionic nature prevents the inclusion in multi-residue analytical methods for environmental monitoring. Consequently, despite its extensive use, data on occurrence of glyphosate in the aquatic environment is still scarce. Based on existing methods, we developed a simplified procedure for the determination of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in water samples using derivatization with fluorenylmethyl chloroformate FMOC-Cl, combined with on-line solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. This method was extensively tested on over 1000 samples of surface water, groundwater, and treated wastewater and proved to be simple, sensitive, and reliable. Limits of quantification of 0.005 µg/L were routinely achieved. Glyphosate and AMPA were detected in the vast majority of stream water samples in the area of Zurich, Switzerland, with median concentrations of 0.11 and 0.20 µg/L and 95th percentile concentrations of 2.1 and 2.6 µg/L, respectively. Stream water data and data from treated wastewater indicated that non-agricultural uses may significantly contribute to the overall loads of glyphosate and AMPA in surface waters. In the investigated groundwater samples, selected specifically because they had shown presence of other herbicides in previous monitoring programs, glyphosate and AMPA were generally not detected, except for two monitoring sites in Karst aquifers, indicating that these compounds show much less tendency for leaching.

Environmental behavior of the chiral herbicide haloxyfop. 1. Rapid and preferential interconversion of the enantiomers in soil.

Haloxyfop-methyl is a chiral herbicide that was first introduced as racemate and later replaced by "haloxyfop-P-methyl", mainly consisting of the R-enantiomer, which carries the herbicidal activity. We studied the ester cleavage of haloxyfop-methyl and further degradation and chiral inversion of the acid enantiomers in three different soils using enantioselective gas chromatography-mass spectrometry. Our results confirm the rapid ester hydrolysis of haloxyfop-methyl with half-lives of a few hours and indicate that hydrolysis is weakly enantioselective. Further degradation of haloxyfop was slower with half-lives of several days. In all three soils, S-haloxyfop was rapidly converted to R-haloxyfop. In sterile soil, no degradation and no inversion were observed, indicating that both processes are biologically mediated. In soil where 50% of the water had been replaced by deuterium oxide, significant H-D exchange in haloxyfop was observed, pointing to a reaction mechanism involving abstraction of the proton at the chiral center of the molecule.

The chiral herbicide beflubutamid (II): Enantioselective degradation and enantiomerization in soil, and formation/degradation of chiral metabolites.

Beflubutamid is a chiral soil herbicide currently marketed as racemate against dicotyledonous weeds in cereals. Biotests have shown that (-)-beflubutamid is at least 1000× more active than (+)-beflubutamid. Potential substitution of the racemate by (-)-beflubutamid should therefore be further considered. Here, we investigated the degradation behavior in soils and formation and degradation of two chiral metabolites. Laboratory incubation experiments were performed with an alkaline and an acidic soil. The compounds were analyzed by enantioselective GC-MS. Degradation rate constants were determined by kinetic modeling. In the alkaline soil, degradation of beflubutamid was slightly enantioselective, with slower degradation of the herbicidally active (-)-enantiomer. In the acidic soil, however, both enantiomers were degraded at similar rates. In contrast, degradation of a phenoxybutanamide metabolite was highly enantioselective. Chiral stability of beflubutamid and its metabolites was studied in separate incubations with the pure enantiomers in the same soils. In these experiments, (-)-beflubutamid was not converted to the nonactive (+)-enantiomer and vice versa. Significant enantiomerization was, however, observed for the major metabolite, a phenoxybutanoic acid. With regard to biological activity and behavior in soils, enantiopure (-)-beflubutamid definitively has the potential to substitute for the racemic herbicide.

The chiral herbicide beflubutamid (I): Isolation of pure enantiomers by HPLC, herbicidal activity of enantiomers, and analysis by enantioselective GC-MS.

For many chiral pesticides, little information is available on the properties and fate of individual stereoisomers. A basic data set would, first of all, include stereoisomer-specific analytical methods and data on the biological activity of stereoisomers. The herbicide beflubutamid, which acts as an inhibitor of carotenoid biosynthesis, is currently marketed as racemate against dicotyledonous weeds in cereals. Here, we present analytical methods for enantiomer separation of beflubutamid and two metabolites based on chiral HPLC. These methods were used to assign the optical rotation and to prepare milligram quantities of the pure enantiomers for further characterization with respect to herbicidal activity. In addition, sensitive analytical methods were developed for enantiomer separation and quantification of beflubutamid and its metabolites at trace level, using chiral GC-MS. In miniaturized biotests with garden cress, (-)-beflubutamid showed at least 1000× higher herbicidal activity (EC50, 0.50 µM) than (+)-beflubutamid, as determined by analysis of chlorophyll a in 5-day-old leaves. The agricultural use of enantiopure (-)-beflubutamid rather than the racemic compound may therefore be advantageous from an environmental perspective. In further biotests, the (+)-enantiomer of the phenoxybutanoic acid metabolite showed effects on root growth, possibly via an auxin-type mode of action, but at 100× higher concentrations than the structurally related herbicide (+)-mecoprop.

Saccharin and other artificial sweeteners in soils: estimated inputs from agriculture and households, degradation, and leaching to groundwater.

Artificial sweeteners are consumed in substantial quantities as sugar substitutes and were previously shown to be ubiquitously present in the aquatic environment. The sweetener saccharin is also registered as additive in piglet feed. Saccharin fed to piglets was largely excreted and, consequently, found in liquid manure at concentrations up to 12 mg/L, where it was stable during 2 months of storage. Saccharin may thus end up in soils in considerable quantities with manure. Furthermore, other studies showed that saccharin is a soil metabolite of certain sulfonylurea herbicides. Sweeteners may also get into soils via irrigation with wastewater-polluted surface water, fertilization with sewage sludge (1-43 µg/L), or through leaky sewers. In soil incubation experiments, cyclamate, saccharin, acesulfame, and sucralose were degraded with half-lives of 0.4-6 d, 3-12 d, 3-49 d, and 8-124 d, respectively. The relative importance of entry pathways to soils was compared and degradation and leaching to groundwater were evaluated with computer simulations. The data suggest that detection of saccharin in groundwater (observed concentrations, up to 0.26 µg/L) is most likely due to application of manure. However, elevated concentrations of acesulfame in groundwater (up to 5 µg/L) may result primarily from infiltration of wastewater-polluted surface water through stream beds.

Composition of aldrin, dieldrin, and photodieldrin enantiomers in technical and environmental samples.

Aldrin and dieldrin belong to the group of polycyclic chlorinated insecticides that are banned under the Stockholm Convention (POP Convention). Despite the fact that the use of these compounds ceased many years ago, aldrin and, in particular, dieldrin are still present in the environment from former applications, leading occasionally to contamination of agricultural produce and food, particularly Cucurbitaceae. These prochiral compounds have a complex stereochemistry. In the environment, aldrin is rapidly converted to its epoxide, dieldrin. Photolysis is one of the environmental transformation processes reported to be important for the compounds, leading to photoproducts such as photoaldrin and photodieldrin. In contrast to the parent compounds, photoaldrin and photodieldrin are chiral and exist as pairs of enantiomers. Although dieldrin and its metabolites have been extensively reviewed, the chirality of many of its metabolites has so far not been considered. In this study, the composition of technical aldrin and dieldrin from the 1950s and their photoproducts was investigated using both non-enantioselective and enantioselective gas chromatography with detection by several mass spectrometric techniques. Full enantiomer resolution of photodieldrin was achieved using a column with a silylated gamma-cyclodextrin as chiral selector. Photoaldrin, however, showed peak broadening, indicating some marginal resolution of the enantiomers. Whereas photodieldrin was formed as a racemate from both aldrin and dieldrin by natural sunlight, the analysis of environmental and biological samples (soil, biota) indicated its presence mostly with enantiomer compositions clearly differing from 1:1. The presence of photodieldrin in soil, treated more than 40 years ago with aldrin or dieldrin, documents that the photoreaction of dieldrin plays some role in the transformation of the compounds in the environment and that enantioselective biological processes are involved in its further transformation. The preliminary data also indicate that photodieldrin probably is not bioaccumulated more than dieldrin.

Hydrophilic anthropogenic markers for quantification of wastewater contamination in ground- and surface waters.

Hydrophilic, persistent markers are useful to detect, locate, and quantify contamination of natural waters with domestic wastewater. The present study focused on occurrence and fate of seven marker candidates including carbamazepine (CBZ), 10,11-dihydro-10,11-dihydroxycarbamazepine (DiOH-CBZ), primidone (PMD), crotamiton (CTMT), N-acetyl-4-aminoantipyrine (AAA), N-formyl-4-aminoantipyrine (FAA), and benzotriazole (BTri) in wastewater treatment plants (WWTPs), lakes, and groundwater. In WWTPs, concentrations from 0.14 microg/L to several micrograms per liter were observed for all substances, except CTMT, which was detected at lower concentrations. Loads determined in untreated and treated wastewater indicated that removal of the potential markers in WWTPs is negligible; only BTri was partly eliminated (average 33%). In lakes, five compounds, CBZ, DiOH-CBZ, FAA, AAA, and BTri, were consistently detected in concentrations of 2 to 70 ng/L, 3 to 150 ng/L, less than the limit of quantification to 30 ng/L, 2 to 80 ng/L, and 11 to 920 ng/L, respectively. Mean per capita loads in the outflows of the lakes suggested possible dissipation in surface waters, especially of AAA and FAA. Nevertheless, concentrations of CBZ, DiOH-CBZ, and BTri correlated with the actual anthropogenic burden of the lakes by domestic wastewater, indicating that these compounds are suitable for quantification of wastewater contamination in lakes. Marker candidates were also detected in a number of groundwater samples. Carbamazepine concentrations up to 42 ng/L were observed in aquifers with significant infiltration of river water, receiving considerable wastewater discharges from WWTPs. Concentration ratios between compounds indicated some elimination of BTri and DiOH-CBZ during subsurface passage or in groundwater, while CBZ and PMD appeared to be more stable and thus are promising wastewater markers for groundwater. The wastewater burden in groundwater, estimated with the markers CBZ and PMD, reached up to 6%.

Ubiquitous occurrence of the artificial sweetener acesulfame in the aquatic environment: an ideal chemical marker of domestic wastewater in groundwater.

Artificial low-calorie sweeteners are consumed in considerable quantities with food and beverages. After ingestion, some sweeteners pass through the human metabolism largely unaffected, are quantitatively excreted via urine and feces, and thus reach the environment associated with domestic wastewater. Here, we document the widespread occurrence of four sweeteners in the aquatic environment and show that one of these compounds, acesulfame, meets all of the criteria of an ideal marker for the detection of domestic wastewater in natural waters, particularly groundwater. Acesulfame was consistently detected in untreated and treated wastewater (12-46 microg/L), in most surface waters, in 65% of the investigated groundwater samples, and even in several tap water samples (up to 2.6 microg/L) from Switzerland. The sweetener was not eliminated in wastewater treatment plants (WWTPs) and was quite persistent in surface waters, where concentrations increased with population in the catchment area and decreased with water throughflow. The highest concentrations in groundwater, up to 4.7 microg/L, were observed in areas with significant infiltration of river water, where the infiltrating water received considerable discharges from WWTPs. Given the currently achieved detection limit of approximately 0.01 microg/L, it is possible to trace the presence of > or = 0.05% wastewater in groundwater.

Azole fungicides: occurrence and fate in wastewater and surface waters.

The mode of action of azole compounds implies a potential to affect endocrine systems of different organisms and is reason for environmental concern. The occurrence and fate of nine agricultural azole fungicides, some of them also used as biocides, and four azole pharmaceuticals were studied in wastewater treatment plants (WWTPs) and lakes in Switzerland. Two pharmaceuticals (fluconazole, clotrimazole, 10-110 ng L(-1)) and two biocides (propiconazole, tebuconazole, 1-30 ng L(-1)) were consistently observed in WWTP influents. Loads determined in untreated and treated wastewater indicated thatfluconazole, propiconazole, and tebuconazole were largely unaffected by wastewater treatment, but clotrimazole was effectively eliminated (> 80%). Incubation studies with activated sludge showed no degradation for fluconazole and clotrimazole within 24 h, but strong sorption of clotrimazole to activated sludge. Slow degradation and some sorption were observed for tebuconazole and propiconazole (degradation half-lives, 2-3 d). In lakes, fluconazole, propiconazole, and tebuconazole were detected at low nanogram-per-liter levels. Concentrations of the pharmaceutical fluconazole correlated with the expected contamination by domestic wastewater, but not those of the biocides. Per capita loads of propiconazole and tebuconazole in lakes suggested additional inputs; for example, from agricultural use or urban runoff rainwater.

Nicotine derivatives in wastewater and surface waters: application as chemical markers for domestic wastewater.

Nicotine is extensively metabolized in the human body to a number of compounds, which may enter natural waters via discharge of domestic wastewater. However, little is known on exposure of and potential effects on the aquatic environment. In this study, two major urinary metabolites, cotinine and 3'-hydroxycotinine, as well as a further tobacco alkaloid, N-formylnornicotine, were measured in wastewater and water from Swiss lakes using an analytical procedure based on SPE and LC-MS/MS SRM with cotinine-d3 as internal standard (LOQs, 1.0-1.5 ng/L). Typical concentrations of cotinine and 3'-hydroxycotinine were approximately 1-10 microg/L in untreated wastewater, but clearly less in treated wastewater (approximately 0.01-0.6 microg/L), corresponding to elimination efficiencies of 90-99%. N-Formylnornicotine, however,was found at similar concentrations in untreated and treated wastewater (0.02-0.15 microg/L). Its apparent persistence during wastewater treatment was further confirmed by incubation experiments with activated sludge. In lakes, cotinine, 3'-hydroxycotinine, and N-formylnornicotine were detected at concentrations up to 15, 80, and 6 ng/L, respectively. Concentrations in lakes correlated with the expected anthropogenic burden by domestic wastewater (ratio population per water throughflow), demonstrating the suitability of these nicotine derivatives as hydrophilic, anthropogenic markers. In small receiving waters with significant wastewater discharges, concentrations of a few hundred ng/L may be expected. Possible ecotoxicological risks associated with such environmental concentrations, can, however, not be assessed at present as data on effects on aquatic organisms are very limited, in particular on long-term effects.

Hydroxylated metabolites of beta- and delta-hexachlorocyclohexane: bacterial formation, stereochemical configuration, and occurrence in groundwater at a former production site.

Although the use of hexachlorocyclohexane (HCH), one of the most popular insecticides after the Second World War, has been discontinued in many countries, problems remain from former production and waste sites. Despite the widespread occurrence of HCHs, the environmental fate of these compounds is not fully understood. In particular, environmental metabolites of the more persistent beta-HCH and delta-HCH have not been fully identified. Such knowledge, however, is important to follow degradation and environmental fate of the HCHs. In the present study, several hydroxy metabolites that formed during incubation of beta- and delta-HCH with the common soil microorganism Sphingobium indicum B90A were isolated, characterized, and stereochemically identified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). The metabolites were identified as isomeric pentachlorocyclohexanols (B1, D1) and tetrachlorocyclohexane-1,4-diols (B2, D2); delta-HCH additionally formed a tetrachloro-2-cyclohexen-1-ol (D3) and a trichloro-2-cyclohexene-1,4-diol (D4), most likely by hydroxylation of delta-pentachlorocyclohexene (delta-PCCH), initially formed by dehydrochlorination. The dehydrochlorinase LinA was responsible for conversion of delta-HCH into delta-PCCH, and the haloalkane dehalogenase LinB was responsible for the transformation of beta-HCH and delta-HCH into B1 and D1, respectively, and subsequently into B2 and D2, respectively. LinB was also responsible for transforming delta-PCCH into D3 and subsequently into D4. These hydroxylations proceeded in accordance with SN2 type reactions with initial substitution of equatorial Cls and formation of axially hydroxylated stereoisomers. The apparently high reactivity of equatorial Cls in beta- and delta-HCH toward initial hydroxylation by LinB of Sphingobium indicum B90A is remarkable when considering the otherwise usually higher reactivity of axial Cls. Several of these metabolites were detected in groundwater from a former HCH production site in Switzerland. Their presence indicates that these reactions proceed under natural environmental conditions and that the metabolites are of environmental relevance.

Occurrence and fate of the cytostatic drugs cyclophosphamide and ifosfamide in wastewater and surface waters.

The two oxazaphosphorine compounds cyclophosphamide and ifosfamide are important cytostatic drugs used in the chemotherapy of cancer and in the treatment of autoimmune diseases. Their mechanism of action, involving metabolic activation and unspecific alkylation of nucleophilic compounds, accounts for genotoxic effects described in the literature and is reason for environmental concern. The occurrence and fate of cyclophosphamide and ifosfamide were studied in wastewater treatment plants (WWTPs) and surface waters in Switzerland, using a highly sensitive analytical method based on solid-phase extraction and liquid chromatography tandem mass spectrometry. The compounds were detected in untreated and treated wastewater at concentrations of <0.3-11 ng/L, which corresponded well with concentrations predicted from consumption data and typical renal excretion rates. Weekly loads determined in influent and effluent wastewater were comparable and suggested a high persistence in WWTPs. Furthermore, no degradation was observed in activated sludge incubation experiments within 24 h at concentrations of approximately 100 ng/L. Processes that may be relevant for elimination in natural waterbodies were studied with a set of incubation experiments in the laboratory. After extrapolation to natural conditions in surface waters, a slow dark-chemical degradation (half-lives on the order of years) is the most important transformation process. Degradation by photochemically formed HO* radicals may be of some relevance only in shallow, clear, and nitrate-rich waterbodies but could be further exploited for elimination of these compounds by advanced oxidation processes, i.e., in a treatment of hospital wastewater. In surface waters, concentrations ranged from < or =50 to 170 pg/L and were thus several orders of magnitude lower than the levels at which acute ecotoxicological effects have been reported in the literature (mg/L range). However, due to a lack of studies on chronic effects on aquatic organisms and data on occurrence and effects of metabolites, a final risk assessment cannot be made.

Influence of pH on the stereoselective degradation of the fungicides epoxiconazole and cyproconazole in soils.

Many pesticides are chiral and consist of two or more enantiomers/stereoisomers, which may differ in biological activity, toxicity, effects on nontarget organisms, and environmental fate. In the last few years, several racemic compounds have been substituted by enantiomer-enriched or single-isomer compounds ("chiral switch"). In this context, the stereoselective degradation in soils is an important part of a benefit-risk evaluation, but the understanding of the environmental factors affecting the chiral preferences is limited. In this study, the stereoselective degradation of the fungicides epoxiconazole and cyproconazole was investigated in different soils, selected to cover a wide range of soil properties. The fungicides were incubated under laboratory conditions and the degradation and configurational stability of the stereoisomers were followed over time using enantioselective GC-MS with a gamma-cyclodextrin derivative as chiral selector. In alkaline and slightly acidic soils, the degradation of epoxiconazole was clearly enantioselective, whereas in more acidic soils, both enantiomers were degraded at similar rates (overall half-lives 78-184 d). The enantioselectivity, expressed as ES = (k(i) - k(j))/ (k(i) + k(j)), ranged from -0.4 in alkaline soils (faster degradation of enantiomer j) to approximately 0 in acidic soils (non-enantioselective), and showed a reasonably linear correlation with the soil pH. The four stereoisomers of cyproconazole (overall half-lives 5-223 d) were also degraded at different rates in the various soils, but only the stereoselectivities between epimers showed some correlations with pH, whereas enantioselectivities did not. Both fungicides were configurationally stable in soils, i.e., no enantiomerization or epimerization was observed. Correlations between pH and ES have previously been reported for other pesticides (metalaxyl, dichlorprop, mecoprop), but the presence or absence of such correlations is not obviously linked to the pathways of degradation. It can be assumed that different microorganisms and enzymes are involved in the primary degradation of these compounds, but on which level soil pH has an influence on ES remains to be investigated.

Combined sewer overflows to surface waters detected by the anthropogenic marker caffeine.

Continuous progress in wastewater treatment technology and the growing number of households connected to wastewater treatment plants (WWTPs) have generally resulted in decreased environmental loading of many pollutants. Nonetheless, further reduction of pollutant inputs is required to improve the quality of surface waters in densely populated areas. In this context, the relative contribution of combined sewer overflows as sources of wastewater-derived contaminants has attracted more and more attention, but the quantitative importance of these overflows has barely been investigated. In this study, caffeine was successfully used as a chemical marker to estimate the fraction of sewer overflows in the catchment area of lake Greifensee, Switzerland. Caffeine is a ubiquitous compound in raw, domestic wastewater with typical per capita loads of approximately 16 mg person(-1) d(-1). In WWTPs of the Greifensee region, caffeine is largely eliminated (>99%), resulting in much smaller loads of < or = 0.15 mg person(-1) d(-1) in treated wastewater. However, in receiving streams as in the inflows to Greifensee, caffeine loads (0.1-1.6 mg person(-1) d(-1)) were higher than those in WWTP effluents, indicating additional sources. As the loads in the streams correlated with precipitation during sampling, it was concluded that combined sewer overflows were the most likely source of caffeine. Using a mass balance approach, it was possible to determine the fraction of wastewater (in dry weather equivalents) discharged untreated to the receiving streams (up to 10%, annual mean, approximately 2-3%). The concept of caffeine as a marker for combined sewer overflows was then applied to estimate phosphorus inputs to Greifensee with untreated and treated wastewater (approximately 1.5 and 2.0 t P y(-1), respectively), which corresponded well with P inputs determined in a separate study based on hydraulic considerations. For compounds with high elimination in WWTPs such as phosphorus (96-98% in the Greifensee area), inputs from combined sewer overflows are thus of similar magnitude as inputs from treated wastewater. The study demonstrated that caffeine is a suitable marker for untreated wastewater (from combined sewer overflows, direct discharges, etc.), but its sensitivity depends on regional conditions and decreases with decreasing elimination efficiency in WWTPs.

Enantioselective transformation of alpha-hexachlorocyclohexane by the dehydrochlorinases LinA1 and LinA2 from the soil bacterium Sphingomonas paucimobilis B90A.

Sphingomonas paucimobilis B90A contains two variants, LinA1 and LinA2, of a dehydrochlorinase that catalyzes the first and second steps in the metabolism of hexachlorocyclohexanes (R. Kumari, S. Subudhi, M. Suar, G. Dhingra, V. Raina, C. Dogra, S. Lal, J. R. van der Meer, C. Holliger, and R. Lal, Appl. Environ. Microbiol. 68:6021-6028, 2002). On the amino acid level, LinA1 and LinA2 were 88% identical to each other, and LinA2 was 100% identical to LinA of S. paucimobilis UT26. Incubation of chiral alpha-hexachlorocyclohexane (alpha-HCH) with Escherichia coli BL21 expressing functional LinA1 and LinA2 S-glutathione transferase fusion proteins showed that LinA1 preferentially converted the (+) enantiomer, whereas LinA2 preferred the (-) enantiomer. Concurrent formation and subsequent dissipation of beta-pentachlorocyclohexene enantiomers was also observed in these experiments, indicating that there was enantioselective formation and/or dissipation of these enantiomers. LinA1 preferentially formed (3S,4S,5R,6R)-1,3,4,5,6-pentachlorocyclohexene, and LinA2 preferentially formed (3R,4R,5S,6S)-1,3,4,5,6-pentachlorocyclohexene. Because enantioselectivity was not observed in incubations with whole cells of S. paucimobilis B90A, we concluded that LinA1 and LinA2 are equally active in this organism. The enantioselective transformation of chiral alpha-HCH by LinA1 and LinA2 provides the first evidence of the molecular basis for the changed enantiomer composition of alpha-HCH in many natural environments. Enantioselective degradation may be one of the key processes determining enantiomer composition, especially when strains that contain only one of the linA genes, such as S. paucimobilis UT26, prevail.

Stereoisomer composition of the chiral UV filter 4-methylbenzylidene camphor in environmental samples.

4-Methylbenzylidene camphor (4-MBC) is an important organic UV filter used in many personal care products such as sunscreens and cosmetics. After use, 4-MBC may enter the aquatic environment due to its release from skin during recreational activities (swimming, bathing) and from personal hygiene measures (washing, laundering of cloths) via wastewater treatment plants (WWTPs). In fact, 4-MBC has been detected in wastewater, in surface waters, and even in fish. 4-MBC can exist as distinct cis-(Z)- and trans-(E)-isomers, both of which are chiral. Despite the fact that stereoisomers often show a different biological behavior, the stereochemistry of 4-MBC has hardly ever been considered in environmental or biological studies. In this study, enantioselective gas chromatography-mass spectrometry (GC-MS) was used to determine the stereoisomer composition of 4-MBC. For stereoisomer assignment, the pure enantiomers of (E)-4-MBC were synthesized from (+)- and (-)-camphor. The photochemical isomerization (sunlight) of these (E)-isomers to the corresponding (Z)-isomers eventually allowed the configurational assignment of all four stereoisomers of 4-MBC. In a technical material and in a major brand sun lotion, 4-MBC was shown to consist entirely (>99%) of (E)-isomers and to be racemic (R/S, 1.00 +/- 0.02). Wastewater showed the presence of both (E)- and (Z)-4-MBC with a clear excess of (E)-isomers (E > Z). Untreated wastewater showed a nearly racemic composition (R/S= 0.95-1.09), suggesting that most if not all commercial 4-MBC is racemic. Treated wastewater indicated some excess of (R)- or (S)-stereoisomers (R/S, 0.89-1.17), likely as a result of some enantioselective (bio)degradation in WWTPs. Residues of 4-MBC in lakes and in a river with inputs from WWTPs and/or recreational activities consisted mainly of (E)-4-MBC and, with exception of one lake (Greifensee), showed a small enantiomer excess (R/S, 1.04-1.16). In Greifensee, 4-MBC showed a higher enantiomer excess (R/S, 1.70-1.83), probably as a result of more extensive biotic degradation in this lake. The analysis of 4-MBC in a small number of fish from these lakes indicated residues with nearly racemic compositions or a moderate enantiomer excess (R/S, approximately 1.0-1.2) in roach (Rutilus rutilus), whereas in perch (Perca fluviatilis) a much higher enantiomer excess (R/S, approximately 5) was observed. The data indicate that the stereoisomer composition of 4-MBC in environmental samples is not only a function of initial product composition but is also modified by enantioselective processes in lakes and biota (fish).

Occurrence of some organic UV filters in wastewater, in surface waters, and in fish from Swiss Lakes.

Organic UV filters are used in personal care products such as sunscreen products, and in cosmetics, beauty creams, skin lotions, lipsticks, hair sprays, hair dyes, shampoos, and so forth. The compounds enter the aquatic environmentfrom showering, wash-off, washing (laundering), and so forth via wastewater treatment plants (WWTPs) ("indirect inputs") and from recreational activities such as swimming and bathing in lakes and rivers ("direct inputs"). In this study, we investigated the occurrence of four important organic UV filter compounds (benzophenone-3, BP-3; 4-methylbenzylidene camphor, 4-MBC; ethylhexyl methoxy cinnamate, EHMC; octocrylene, OC) in wastewater, and in water and fish from various Swiss lakes, using gas chromatographic/mass spectrometric analyses. All four UV filters were present in untreated wastewater (WWTP influent) with a maximum concentration of 19 microg L(-1) for EHMC. The data indicate a seasonal variation with influent loads higher in the warmer season (June 2002) than in the colder one (April 2002). The influent loads were in the order EHMC > 4-MBC approximately BP-3 > OC. The concentrations in treated wastewater (WWTP effluent) were considerably lower, indicating substantial elimination in the plants. 4-MBC was usually the most prevalent compound (maximum concentration, 2.7 microg L(-1)), followed by BP-3, EHMC, and OC. UV filters were also detected in Swiss midland lakes and a river (Limmat) receiving inputs from WWTPs and recreational activities. However, all concentrations were low (<2-35 ng L(-1)); no UV filters (<2 ng L(-1)) were detected in a remote mountain lake. Data from passive sampling using semipermeable membrane devices (SPMDs) supported the presence of these UV filters in the lakes and the river and suggested some potential for accumulation of these compounds in biota. SPMD-derived water concentrations increased in the order Greifensee < Zürichsee < Hüttnersee. This order is reversed from that observed for methyl triclosan, used as a chemical marker for WWTP-derived lipophilic contaminants in the lakes. This indicated inputs of UV filters from sources other than WWTPs to the lakes during summer,for example,inputs from recreational activities. Fish (white fish, Coregonus sp.; roach, Rutilus rutilus; perch, Perca fluviatilis) from these lakes contained low but detectable concentrations of UV filters, in particular, 4-MBC (up to 166 ng g(-1) on a lipid basis). 4-MBC concentrations relative to methyl triclosan were lower in fish than in SPMDs exposed in the same lakes, suggesting that 4-MBC is less bioaccumulated than expected or metabolized in fish. The lipid-based bioconcentration factor (BCF(L)) estimated from the fish (roach) data and SPMD-derived water concentrations was about 1-2.3 x 10(4) and thus approximately 1 order of magnitude lower than expected from its Kow value.

Occurrence of UV filter compounds from sunscreens in surface waters: regional mass balance in two Swiss lakes.

Consumer care products often contain UV filters, organic compounds which absorb ultraviolet light. These compounds may enter surface waters directly (when released from the skin during swimming and bathing) or indirectly via wastewater treatment plants (when released during showering or washed from textiles). Predicted and measured UV filter concentrations were compared in a regional mass balance study for two Swiss lakes: Lake Zurich, a typical midland lake which is also an important drinking water resource, and Hüttnersee, a small bathing lake. Both lakes are extensively used for recreational activities and considerable direct input of UV filters is thus expected. This input was estimated from the number of visitors at swimming areas around the lakes and a survey of the usage of sunscreen products among these visitors. Possible additional indirect input via wastewater treatment plants was not considered in this study. The quantitatively most important UV filters, as indicated by the survey data, ethylhexyl methoxycinnamate, octocrylene, 4-methylbenzylidene camphor, butyl methoxydibenzoylmethane, and benzophenone-3, all lipophilic compounds, were selected for analysis by gas chromatography-mass spectrometry. Concentrations of individual UV filters in water from Lake Zurich were low, ranging from <2 ng l(-1) (detection limit) to 29 ng l(-1), and somewhat higher at Hüttnersee, ranging from <2 to 125 ng l(-1), with the highest concentrations found in summer, consistent with direct inputs to the lakes during this time. The concentrations were clearly lower than predicted from input estimates based on the surveys. This may be in part due to (i) an overestimation of these inputs (e.g. less than the 50% wash-off of UV filters assumed to occur during swimming), and (ii) some removal of these compounds from the lakes by degradation and/or sorption/sedimentation. UV filters were also detected in semipermeable membrane devices (SPMDs) deployed at Lake Zurich and Greifensee, another midland lake, at concentrations of 80-950 ng SPMD(-1), confirming the presence of the compounds in surface waters and indicating a certain potential for bioaccumulation. SPMD-derived water concentrations were in the range of 1-10 ng l(-1) and thus corresponded well with those determined in water directly. No UV filters were detected above blank levels in SPMDs deployed at a remote mountain lake used for background measurements.

Occurrence of methyl triclosan, a transformation product of the bactericide triclosan, in fish from various lakes in Switzerland.

The bactericide triclosan and methyl triclosan, an environmental transformation product thereof, have been previously detected in lakes and a river in Switzerland. Both compounds are emitted via wastewater treatment plants (WWTPs), with methyl triclosan probably being formed by biological methylation. Passive sampling with semi-permeable membrane devices (SPMDs) showed the presence of methyl triclosan in some lakes, suggesting some potential for bioaccumulation of the compound. In this study, we report the presence of methyl triclosan in fish (white fish, Coregonus sp.; roach, Rutilus rutilus) from various lakes in Switzerland receiving inputs from WWTPs. Identification of the compound was based on mass spectral (MS) evidence including MS/MS data. The concentrations of methyl triclosan in the fish were up to 35 ng g(-1) on a wet weight basis and up to 365 ng g(-1) on a lipid basis with concentrations in a relatively narrow range for fish from the same lake (Thunersee, 4-6 ng g(-1); Zürichsee, 32-62 ng g(-1); Pfäffikersee, 43-56 ng g(-1); Greifensee, 165-365 ng g(-1), lipid basis). No methyl triclosan (<1 ng g(-1), lipid basis) was detected in fish (lake trout, Salmo trutta) from a remote lake in Sweden (Häbberstjärnen) and in fish (roach) from a small lake in Switzerland with no input from WWTPs (Hüttnersee, <2-<5 ng g(-1), lipid basis). The concentrations of methyl triclosan in fish correlated (r2 = 0.85) with the ratio of population in the watershed to water throughflow of the lakes (P/Q ratio), which is considered to be a measure for the domestic burden from WWTPs to a lake. Passive sampling with SPMDs confirmed the presence of methyltriclosan in lakes and a river (Zürichsee and Greifensee; Limmat) but not in a remote mountain lake (Jörisee) and in Hüttnersee. The bioconcentration factor (BCF) of methyl triclosan estimated from the fish data and SPMD-derived water concentrations was in the order of 1-2.6 x 10(5) (lipid basis) and thus in the range of other persistent organic pollutants. SPMDs were found to be reliable for monitoring low concentrations of methyl triclosan in surface water. Methyl triclosan appears to be a suitable marker for WWTP-derived lipophilic contaminants in the aquatic environment and fish.

Enantioselective degradation of metalaxyl in soils: chiral preference changes with soil pH.

Chiral pesticides are often degraded enantio-/stereoselectively in soils. Degradation is typically studied with one or a small number of soils so that it is not possible to extrapolate the findings on chiral preference to other soils. For this study, the fungicide metalaxyl was chosen as a "chiral probe" to investigate its enantioselective degradation in 20 different soils, selected primarily to cover a wide range of soil properties (e.g., acidic/alkaline, aerobic/ anaerobic) rather than to consider soils of agricultural importance. Racemic metalaxyl was incubated in these soils under laboratory conditions, and the degradation of the enantiomers as well as the enantioselective formation/ degradation of the primary major metabolite, metalaxyl acid, was followed over time, using enantioselective GC-MS after ethylation with diazoethane. In aerobic soils with pH > 5, the fungicidally active R-enantiomer was degraded faster than the S-enantiomer (k(R) > k(S)), leading to residues with a composition [S] > [R]. However, in aerobic soils with pH 4-5, both enantiomers were degraded at similar rates (k(R) approximately k(S)), and in aerobic soils with pH < 4 and in most anaerobic soils, the enantioselectivity was reversed (k(R) < k(S)). These considerable soil-to-soil variations were observed with soils from locations close to each other, in one case even within a single soil profile. Liming and acidification of a "nonenantioselective" soil prior to incubation resulted in enantioselective degradation with k(R)> k(S) and k(R) < k(S), respectively. While the enantioselectivity (expressed as ES = (k(R) - k(S))/(k(R) + k(S))) of metalaxyl degradation in aerobic soils apparently correlated with soil pH, no such correlation was found for metalaxyl acid. Reevaluation of published kinetic data for the herbicides dichlorprop and mecoprop indicated similar correlations between soil pH and ES as for metalaxyl.