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PubMed1990

Pollution by the fungicide pentachloronitrobenzene in an intensive farming area in Japan.

Environmental pollution by pentachloronitrobenzene (PCNB) was investigated at Tsumagoi, an intensive farming area, where a great amount of PCNB has been applied. High concentrations of PCNB were detected in river water near an area of cabbage cultivation. Further, pentachloroaniline (PCA) and pentachlorothioanisole (PCTA), which are the principal biodegradation products of PCNB, were also detected, and their ratios to PCNB were higher in autumn than in summer. PCNB concentrations in soil were similar to those of river sediment, in which PCNB was concentrated 5000-10,000 times over levels in river water. The biodegradation rate of PCNB in river water was higher than in river sediment and soil. The formation rates of PCA from PCNB were higher in river sediment and soil than in river water. It is considered that PCA remains for a long time in the environment and accumulates in river sediment and soil.

Agriculture↗

PubMed2005

Environmental fate of herbicides trifluralin, metazachlor, metamitron and sulcotrione compared with that of glyphosate, a substitute broad spectrum herbicide for different glyphosate-resistant crops.

The introduction of crops resistant to the broad spectrum herbicide glyphosate, N-(phosphonomethyl)glycine, may constitute an answer to increased contamination of the environment by herbicides, since it should reduce the total amount of herbicide needed and the number of active ingredients. However, there are few published data comparing the fate of glyphosate in the environment, particularly in soil, with that of substitute herbicides. The objective of this study is to compare the fate of glyphosate in three soils with that of four herbicides frequently used on crops that might be glyphosate resistant: trifluralin, alpha,alpha,alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine, and metazachlor, 2-chloro-N-(pyrazol-1-ylmethyl)acet-2',6'-xylidide for oilseed rape, metamitron, 4-amino-4,5-dihydro-3-methyl-6-phenyl-1,2,4-triazin-5-one for sugarbeet and sulcotrione, 2-(2-chloro-4-mesylbenzoyl)cyclohexane-1,3-dione for maize. The distribution of herbicides between the volatilized, mineralized, extractable and non-extractable fractions was studied, along with the formation of their metabolites in laboratory experiments using 14C-labelled herbicides, over a period of 140 days. The main dissipation pathways were mineralization for glyphosate and sulcotrione, volatilization for trifluralin and non-extractable residues formation for metazachlor and metamitron. The five herbicides had low persistence. Glyphosate had the shortest half-life, which varied with soil type, whereas trifluralin had the longest. The half-lives of metazachlor and sulcotrione were comparable, whereas that of metamitron was highly variable. Glyphosate, metazachlor and sulcotrione were degraded into persistent metabolites. Low amounts of trifluralin and metamitron metabolites were observed. At 140 days after herbicide applications, the amounts of glyphosate and its metabolite residues in soils were the lowest in two soils, but not in the third soil, a loamy sand with low pH. The environmental advantage in using glyphosate due to its rapid degradation is counterbalanced by accumulation of aminomethylphosphonic acid specifically in the context of extensive use of glyphosate.

Biodegradation, Environmental↗

PubMed2001

Ecotoxicology of glutaraldehyde: review of environmental fate and effects studies.

Glutaraldehyde is a biocide used in many industrial applications with potential releases to the environment. This review discusses the environmental fate and effects data on this important biocide. Information drawn from this review indicates that glutaraldehyde is acutely toxic to aquatic organisms. Glutaraldehyde is equally toxic to warm water and cold water fish, but is slightly more toxic to freshwater fish than salt water fish. The acute toxicity of glutaraldehyde for avian species is comparable to that for mammalian species. The toxicity of glutaraldehyde is not appreciably increased with repeated long-term exposures. Results from environmental partitioning studies indicate that glutaraldehyde tends to remain in the aquatic compartment and has little tendency to bioaccumulate. Aqueous solutions of glutaraldehyde are stable at room temperature under acidic to neutral conditions, and to sunlight, but unstable at elevated temperatures, and under alkaline conditions. Glutaraldehyde is readily biodegradable in the freshwater environment and has the potential to biodegrade in the marine environment. Aquatic metabolism studies suggest that glutaraldehyde, under aerobic conditions, is metabolized to CO(2) via glutaric acid as an intermediate. Under anaerobic conditions, glutaraldehyde is metabolized to 1,5-pentanediol. Pretreatment with sodium bisulfite is the best method for inactivating glutaraldehyde prior to disposal to treatment systems.

Animals↗

PubMed1998

Pharmaceuticals in the environment--a human risk?

Pharmaceuticals in the environment and their potential toxic effects are emerging research areas, which is also reflected in the drug approval regulation. This far, focus has mainly been directed toward potential effects on nature and wildlife. In this paper, human risk as a consequence of exposure via the environment has been addressed and assessed. The synthetic estrogen 17alpha-ethinylestradiol (EE2), the antibiotic phenoxymethylpenicillin (Pen V), and the antineoplastic drug cyclophosphamide (CP) were chosen as modeling substances based on criteria of receptor specificity, elevated risk for human population groups for which the pharmaceuticals are not therapeutically intended, different modes of action, and prescription frequency. Attention has been focused on emissions from the use phase and subsequent diffuse release via the sewer systems. A reasonable worst-case environmental fate and human exposure were estimated using the software EUSES on worst-case emission quantities. The results indicate a negligible human risk connected to the environmental exposure for these substances. Danish conditions have been used as the modeling area, but the results are assumed to be valid for regions with similar drug consumption profiles.

Biodegradation, Environmental↗

PubMed2006

Environmental fate processes and biochemical transformations of chiral emerging organic pollutants.

This review highlights the analytical chemistry, environmental occurrence, and environmental fate of individual stereoisomers of chiral emerging pollutants, which are modern current-use chemicals of growing environmental concern due to their presence in the environment and potential for deleterious effects. Comparatively little is known about individual stereoisomers of pollutants, which can have differential toxicological effects and can be tracers of biochemical weathering in the environment. Stereoisomers are resolved by gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrophoresis (CE). Separation techniques in environmental analysis are typically coupled to mass spectrometry (MS) and tandem mass spectrometry (MS/MS), as these provide the sensitivity and selectivity needed. The enantiomer composition of phenoxyalkanoic and acetamide herbicides, organophosphorus and pyrethroid pesticides, chiral polychlorinated biphenyl metabolites, synthetic musks, hexabromocyclododecane, and pharmaceuticals in the environment show species-dependent enantioselectivity from biotransformation and other biologically mediated processes affecting enantiomers differentially. These enantiomer compositions are useful in detecting biologically mediated environmental reactions, apportioning sources of pollutants, and gaining insight into the biochemical fate of chiral pollutants in the environment, which are needed for accurate risk assessment of such chemicals.

Biodegradation, Environmental↗

PubMed2001

Degradation in soil and water and ecotoxicity of rimsulfuron and its metabolites.

The degradation and ecotoxicity of sulfonylurea herbicide rimsulfuron and its major metabolites were examined in batch samples of an alluvial sandy loam and in freshwater. An HPLC-DAD method was adapted to simultaneously identify and quantify rimsulfuron and its metabolites, which was successfully validated by GC-MS analysis. In aqueous solutions, pure rimsulfuron was rapidly hydrolyzed into metabolite 1 (N-(4,6-dimethoxypyrimidin-2-yl)-N-(3-(ethylsulfonyl)-2-pyridinylurea)), which itself was transformed into the more stable metabolite 2 (N-((3-(ethylsulfonyl)-2-pyridinyl)-4,6-dimethoxy-2-pyrimidineamine)), with half-life (t(1/2)) values of 2 and 2.5 days, respectively. Hydrolysis was instantaneous under alkaline conditions (pH = 10). In aqueous suspensions of the alluvial soil (pH = 8), formulated rimsulfuron had a half-life of 7 days, whereas that of metabolite 1 was similar to that in water (about 3.5 days). The degradation of the two major metabolites was also studied in soil suspensions with the pure compounds at concentrations ranging from 1 to 10 mg l(-1). The half-life of metabolite 1 ranged from 3.9 to 5 days, close to the previous values. Metabolite 2 was more persistent and its degradation is strongly dependent on the initial concentration (C0): half-life values ranged from 8.1 to 55 days at 2-10 mg l(-1), respectively. These values are higher than those determined from the kinetics of metabolite 1 transformation into metabolite 2 (t(1/2) = 8-19 days). The ecotoxicity of the three chemicals was evaluated through their effect on Daphnia magna and Vibrio fischeri (Microtox bioassay). No effect was observed on D. magna with 24 and 48 h acute toxicity tests. Similarly, no toxic effect was observed with the Microtox test for the three chemicals in the range of concentrations tested that included the field application dose. Thus, being of low persistence and lacking acute toxicity, these chemicals present a low environmental risk. However, chronic effects should be studied in order to confirm the safety of rimsulfuron and its major metabolites.

Animals↗

PubMed1998

An indicator of pesticide environmental impact based on a fuzzy expert system.

Pesticide use options available to farmers differ strongly with respect to the risks they pose to the environment. This paper proposes a fuzzy expert system to calculate an indicator "Ipest" which reflects an expert perception of the potential environmental impact of the application of a pesticide in a field crop. We defined four modules, one reflecting the presence (rate of application) of the pesticide, the other three reflecting the risk for three major environmental compartments (groundwater, surface water, air). The input variables for these modules are pesticide properties, site-specific conditions and characteristics of the pesticide application. For each input variable two functions describing membership to the fuzzy subsets Favourable (F) and Unfavourable (U) have been defined. These functions are based on criteria drawn from the literature or on the authors' expert judgment. The expert system calculates the value of modules according to the degree of membership of the input variables to the fuzzy subsets F and U and according to sets of decision rules. The four modules can be considered individually or can be aggregated (again according to membership to fuzzy subsets F and U and a set of decision rules) into the indicator Ipest. The system is flexible and can be turned to expert perception, it can be used as a decision aid tool to rank or choose between alternative pesticide application options with respect to their potential environmental impact. Results of a sensitivity analysis and module and Ipest scores for some pesticide application cases are presented. An agro-ecological indicator IPEST, based on the expert system, is proposed as a tool to assess the environmental impact of all pesticide applications related to a crop within a year. The practical implementation of the expert system and its validation are discussed.

Biodegradation, Environmental↗

PubMed2001

Microbial nitrogen cycles: physiology, genomics and applications.

Genes and pathways involved in inorganic nitrogen cycles have been found in traditional as well as unusual microorganisms. These pathways or enzymes play a very important role in the adaptation or survival of these microorganisms under a variety of environmental conditions. Microbial nitrogen metabolism has industrial applications ranging from wastewater treatment to bioremediation and potential future use in biocatalysis for chemical production.

Ammonia↗

PubMed1999

Influence of environmental changes on degradation of chiral pollutants in soils.

Numerous anthropogenic chemicals of environmental concern--including some phenoxy acid herbicides, organophosphorus insecticides, polychlorinated biphenyls, phthalates, freon substitutes and some DDT derivatives--are chiral. Their potential biological effects, such as toxicity, mutagenicity, carcinogenicity, and endocrine disrupter activity, are generally enantiomer-selective, and different enantiomers are preferentially degraded (transformed) by micro-organisms in various environments. Here we use field and laboratory experiments to demonstrate that environmental changes in soils can alter these preferences, and to suggest that the preferences shift owing to different groups of related microbial genotypes being activated by different environmental changes. In Brazilian soils, almost all pasture samples preferentially transformed the non-herbicidal enantiomer of dichlorprop ((RS)-2-(2,4-dichlorophenoxy)propionic acid), while most forest samples either transformed the herbicidal enantiomer more readily or as rapidly as the non-herbicidal enantiomer. Organic nutrient enrichments shifted enantioselectivity for methyl dichlorprop ((RS)-methyl 2-(2,4-dichlorophenoxy)propionic acid) strongly towards preferentially removing the non-herbicidal enantiomer in soils from Brazil and North America, potentially increasing phytotoxicity of its residues relative to that of the racemate. Assessments of the risks chemical pollutants pose to public health and the environment need to take into account the chiral selectivity of microbial transformation processes and their alteration by environmental changes, especially for pesticides as up to 25 per cent are chiral.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2000

Acrylonitrile induces autolysis Bacillus subtilis.

Acrylonitrile (AN) is an industrial chemical used in the manufacture of plastics and other polymers. AN has been reported to be an acute toxin and is a known carcinogen in rodents. When AN was mixed with suspensions of Bacillus subtilis, the bacteria began autolysis. It was determined that AN is partially converted to cyanide, a strong protonophore in B. subtilis. Autolytic enzymes in B. subtilis become active when the protonmotive force is dissipated. The amount of cyanide produced from AN, however, was not enough to promote autolysis in exponential B. subtilis. This is the first report showing that AN may induce autolytic reactions in bacteria. It is suggested the autolysis of B. subtilis may be useful in the environmental monitoring of AN. In addition, the metabolism of AN by bacilli may be useful in bioremediation.

Acrylonitrile↗

PubMed2000

[Chlorinated hydrocarbon insecticides(DDT, methoxychlor, HCH etc.)].

Endocrine disrupting properties of organochlorine(chlorinated hydrocarbon) insecticides are reviewed. Physicochemical properties such as water solubility and partition coefficient of the organochlorine insecticides greatly influence their environmental fates. Insolubility in water and high partition coefficient usually enhance the environmental persistence of the compounds. On the endocrine disrupting properties, an important metabolite of p,p'-DDT, p,p'-DDE, is known to exhibit weak anti-androgenic properties. An isomer o,p'-DDT is estrogenic. Metabolites of methoxychlor, mono-demethylated and di-demethylated methoxychlor derivatives, are weakly estrogenic. Their dehydochlorinated product also exhibits estrogenicity. HCH isomers are environmentally persistent compounds, but there is few reports on their endocrine disrupting properties. Some other organochlorine pesticides such as cyclodienes and chlordecone is reported to be estrogenic.

Androgen Antagonists↗

PubMedDate not supplied

Factors affecting heavy metal uptake in plant selection for phytoremediation.

The heavy metal uptake of ten plant species was studied under different soil and climatic conditions. Effects of soil pH, temperature, plant species and phenophase on the heavy metal content of stems and leaves were determined in pot experiments. Plants and soil samples were collected from a lead/zinc mine ore (Gyöngyösoroszi, Hungary) and characterised by high contents of Pb, Zn, As, Cd, Cu. The possibility of an adapted phytoremediation technology was indicated by different bioconcentration factors (BCF). The BCF depended markedly (10- to 100-fold) on plant species and environmental conditions. Based on our results a "season-adapted" phytoextraction technology with different plant species (utilising their different temperature requirements and/or harvest time) is suggested.

Biodegradation, Environmental↗

PubMed2005

Structural insight into the dioxygenation of nitroarene compounds: the crystal structure of nitrobenzene dioxygenase.

Nitroaromatic compounds are used extensively in many industrial processes and have been released into the environment where they are considered environmental pollutants. Nitroaromatic compounds, in general, are resistant to oxidative attack due to the electron-withdrawing nature of the nitro groups and the stability of the benzene ring. However, the bacterium Comamonas sp. strain JS765 can grow with nitrobenzene as a sole source of carbon, nitrogen and energy. Biodegradation is initiated by the nitrobenzene dioxygenase (NBDO) system. We have determined the structure of NBDO, which has a hetero-hexameric structure similar to that of several other Rieske non-heme iron dioxygenases. The catalytic subunit contains a Rieske iron-sulfur center and an active-site mononuclear iron atom. The structures of complexes with substrates nitrobenzene and 3-nitrotoluene reveal the structural basis for its activity with nitroarenes. The substrate pocket contains an asparagine residue that forms a hydrogen bond to the nitro-group of the substrate, and orients the substrate in relation to the active-site mononuclear iron atom, positioning the molecule for oxidation at the nitro-substituted carbon.

Amino Acid Sequence↗

PubMed1976

Diatom diversity as a function of insecticidal treatment with a controlled-release formulation of chlorpyrifos.

Following treatment with a controlled-release formulation of chlorpyrifos, no substantial differences between diversity estimates were evident for 6 post-treatment weeks for both treated and control plots. By post-treatment week 12, significant decreases in diversity estimates occurred in treated plots, suggesting that a directly proportional relationship exists between chlorpyrifos concentrations and reduced diatom colonization through time. Comparatively, diatom colonization progress "normally" and populations proceeded toward "maturity" in the control plots as indicated by the increase in the diversity estimates between post-treatment weeks 6 and 12. Any adverse effects due to the insecticidal treatment, however, were not considered to be environmentally deleterious in light of the restricted type of habitat (rice culture) in which the chlorpyrifos was used.

Biodegradation, Environmental↗

PubMed2006

Influence of electron donor, oxygen, and redox potential on bacterial perchlorate degradation.

Experiments were conducted to assess the influence of electron donor, redox potential, and dissolved oxygen on bacterial perchlorate degradation. Microcosms containing a diverse, perchlorate-acclimated, bacterial culture fed lactate at a 1:1 electron donor-to-perchlorate ratio (electron-equivalent basis) degraded perchlorate more slowly (k = 0.038 mg ClO4-/mg VSS h) and to a lesser extent than microcosms fed lactate at 2:1 and 4:1 ratios (k = 0.045 mg ClO4-/mg VSS h). The optimal COD/ClO4- ratio to consume all perchlorate and all electron donor was approximately 1.2 mg COD/mg ClO4-. In experiments where the redox potential was held constant, the extent of perchlorate degradation increased with decreasing redox potential, and 100% removal was only achieved at the lowest redox potential examined (-220 mV); however, perchlorate degradation (32% of added perchlorate) was observed as high as +180 mV. Additions of oxygen to actively degrading treatments did not adversely effect perchlorate degradation. It appears, therefore, that addition of excess electron donor is sufficient to negate potential inhibitory effects of molecular oxygen. If the redox conditions are more oxidized, however, the rate and extent of perchlorate degradation will be significantly decreased. This is the first report of perchlorate degradation under oxidized conditions using an environmentally relevant, diverse, bacterial enrichment culture, and this is also the first report of perchlorate reduction occurring at appreciable dissolved oxygen concentrations in a batch system.

Bacteria↗

PubMed1998

Occurrence, fate and effects of pharmaceutical substances in the environment--a review.

Medical substances (pharmaceuticals) are a group of substances that until recently have been exposed to the environment with very little attention. The reason why they may be interesting as environmental micropollutants, is that medical substances are developed with the intention of performing a biological effect. Especially antibiotics used as growth promoters, as feed additives in fish farms are anticipated to end up in the environment. Very little is known about the exposure routes of the medical substances to the environment. Only few investigations have reported findings of medical substances in other field samples than sediment or treated waste water samples. Several substances seem to be persistent in the environment. This paper outlines the different anticipated exposure routes to the environment, summarises the legislation on the subject and gives an outline of present knowledge of occurrence, fate and effect on both the aquatic and terrestrial environments of medical substances. Present knowledge does not reveal if regular therapeutic use may be the source of a substance carried by sewage effluent into the aquatic system, even though clofibrate, a lipid lowering agent, has been identified in ground and tap water samples from Berlin. Further research would be necessary to assess the environmental risk involved in exposing medical substances and metabolites to the environment.

Animals↗

PubMed2002

The potential for anaerobic mineralisation of hydrocarbon constituents of oily drill cuttings from the North Sea seabed.

The potential for natural attenuation of hydrocarbons in oily drill cuttings from the seabed beneath a North Sea oil platform was investigated. The study focused on the anaerobic degradation of n-hexadecane, n-octacosane and naphthalene using additions of 14C-labelled analogues to drill cuttings samples and was conducted under realistic seabed conditions (except pressure) over an 11-month period. No mineralisation of naphthalene was detected over this time period and mineralisation of octacosane represented only 0.5-1.5% of the added label. In contrast, mineralisation of hexadecane was 10-49% after 11 months of incubation. Selective inhibition of key functional bacterial groups revealed the key role of both sulfate reduction and methanogenesis in the degradation process. This study demonstrates the potential for natural attenuation of at least some hydrocarbon constituents of oily drill cuttings under realistic environmental conditions and highlights the involvement of a wide functional consortium in the natural attenuation process.

Bacteria, Anaerobic↗

PubMed2003

Dissipation of the herbicide clopyralid in an allophanic soil: laboratory and field studies.

Soil dissipation of the herbicide clopyralid (3,6-dichloropicolinic acid) was measured in laboratory incubations and in field plots under different management regimes. In laboratory studies, soil was spiked with commercial grade liquid formulation of clopyralid (Versatill, 300 g a.i. L(-1) soluble concentrate) @ 0.8 microg a.i. g(-1) dry soil and the soil water content was maintained at 60% of water holding capacity of the soil. Treatments included incubation at 10 degrees C, 20 degrees C, 30 degrees C, day/night cycles (25/15 degrees C) and sterilized soil (20 degrees C). Furthermore, a field study was conducted at the Waikato Research Orchard near Hamilton, New Zealand starting in November 2000 to measure dissipation rates of clopyralid under differing agricultural situations. The management regimes were: permanent pasture, permanent pasture shielded from direct sunlight, bare ground, and bare ground shielded from direct sunlight. Clopyralid was sprayed in dilute solution @ 600 g a.i. ha(-1) on to field plots. Herbicide residue concentrations in soil samples taken at regular intervals after application were determined by gas chromatograph with electron capture detector. The laboratory experiments showed that dissipation rate of clopyralid was markedly faster in non-sterilized soil (20 degrees C), with a half-life (t1/2) of 7.3 d, than in sterilized soil (20 degrees C) with t1/2 of 57.8 d, demonstrating the importance of micro-organisms in the breakdown process. Higher temperatures led to more rapid dissipation of clopyralid (t1/2, 4.1 d at 30 degrees C vs 46.2 d at 10 degrees C). Dissipation was also faster in the day/night (25/15 degrees C) treatment (t1/2, 5.4 d), which could be partly due to activation of soil microbes by temperature fluctuations. In the field experiment, decomposition of clopyralid was much slower in the shaded plots under pasture (t1/2, 71.5 d) and bare ground (t1/2, 23.9 d) than in the unshaded pasture (t1/2, 5.0 d) and bare ground plots (t1/2, 12.9 d). These studies suggest that environmental factors such as temperature, soil water content, shading, and different management practices would have considerable influence on rate of clopyralid dissipation.

Agriculture↗