Endosulfan and quinalphos residues and toxicity to soil microarthropods after repeated applications in a field investigation

Endosulfan (1,4,5,6,7,7-hexachloro-8,9,10-trinorborn-5-en-2,3-ylenedimethylsulphite) and quinalphos (O,O-diethyl O-quinoxalin-2-yl phosphorothioate) persistence and their effect on soil microarthropods were studied after repeated applications in cotton fields. Dissipation behavior of insecticides after repeated applications was observed from 78 to 292 days after the first insecticide treatment. At any given time the concentrations of endosulfan beta residues were always higher as compared to endosulfan alpha. From 78 to 85 days, 5.0% and 20.4% decrease in alpha and beta endosulfan residues was observed, respectively. Endosulfan beta isomer decreased up to 93.0% in 292 days. Endosulfan sulfate was detected as a major metabolite in the soil samples. Total endosulfan residues decreased by 86.6% from 78 to 292 days. The amounts of quinalphos residues were less as compared to endosulfan at any given time. The residues observed after 78 days of application were 0.88 ng g-1 d wt. soil. At the end of 145 days, a 35.0% decrease in quinalphos residue was observed, which decreased further by 50.9% in 292 days. Among the soil microarthropods studied, Acarina was more sensitive to the applied insecticides as compared to Collembola. Three days after the last treatment, up to 94.5% (p < 0.01) and 71.2% (p < 0.05) decrease in Acarina population was observed in endosulfan and quinalphos treated fields, respectively, compared to control field. In general, no noticeable change in Collembola population was observed after the insecticide treatments.     

Black cherry growth response to ambient ozone and EDU

Field-grown black cherry (Prunus serotina Ehrh.) seedlings were treated with the antioxidant ethylenediurea (EDU) to evaluate height, diameter, and above-ground dry-weight biomass growth response to ambient ozone over four years. Nine blocks with 44 trees/block were used in a randomized complete block design with three foliar spray treatments: (1) 1000 ppm EDU mixed with a surfactant and water; (2) surfactant mixed with water; and (3) water only. In each growing season treatments were applied seven times at approximately 10-day intervals. Repeated measures analysis of variance indicated significant (P< or =0.05) treatment and year effects for log-transformed height and diameter growth over the four-year period. After four years, EDU-treated trees were approximately 17% taller and stem diameters were 21% greater than non-EDU-treated trees. Total above-ground dry-weight biomass at the end of four years was 47% greater for EDU-treated trees compared to non-EDU-treated trees.     

Mobilization of soil organic matter by complexing agents and implications for polycyclic aromatic hydrocarbon desorption

Complexing agents are frequently used in treatment technologies to remediate soils, sediments and wastes contaminated with toxic metals. The present study reports results that indicate that the rate and extent of soil organic matter (SOM) as represented by dissolved natural organic carbon (DNOC) and polycyclic aromatic hydrocarbon (PAH) desorption from a contaminated soil from a manufactured gas plant (MGP) site can be significantly enhanced with the aid of complexing agents. Desorption of DNOC and PAH compounds was pH dependent, with minimal release occurring at pH 2-3 and maximal release at pH 7-8. At pH-6, chelate solutions were shown to dissolve large amounts of humic substances from the soil compared to controls. The complexing agents mobilized polyvalent metal ions, particularly Fe and Al from the soil. Metal ion chelation may disrupt humic (metal ion)-mineral linkages, resulting in mobilization of SOM and accompanying PAH molecules into the aqueous phase; and/or reduce the degree of cross-linking in the soil organic matter phase, which could accelerate PAH diffusion.     

A comparison of the environmental impact of pesticide multiresidues and their occurrence in river waters surveyed by liquid chromatography coupled in tandem with UV diode array detection and mass spectrometry

Twenty-two pesticides and metabolites selected on the basis of a regional priority list, were surveyed in surface river waters by high performance liquid chromatography coupled in tandem with UV diode array detection and mass spectrometry, after an off-line pre-concentration step. Pesticide concentrations ranged between 0.07 and 4.8 microg/l according to the compound and sampling period. Analytical results were linked to the environmental risk of pesticides, evaluated by their system investigation of risk by integration of score (SIRIS) rank.     

Accelerated remediation of pesticide-contaminated soil with zerovalent iron

High pesticide concentrations in soil from spills or discharges can result in point-source contamination of ground and surface waters. Cost-effective technologies are needed for on-site treatment that meet clean-up goals and restore soil function. Remediation is particularly challenging when a mixture of pesticides is present. Zerovalent iron (Fe0) has been shown to promote reductive dechlorination and nitro group reduction of a wide range of contaminants in soil and water. We employed Fe0 for on-site treatment of soil containing > 1000 mg metolachlor, > 55 mg alachlor, > 64 mg atrazine, > 35 mg pendimethalin, and > 10 mg chlorpyrifos kg(-1). While concentrations were highly variable within the windrowed soil, treatment with 5% (w/w) Fe0 resulted in > 60% destruction of the five pesticides within 90 d and increased to > 90% when 2% (w/w) Al2(SO4)3 was added to the Fe0. GC/MS analysis confirmed dechlorination of metolachlor and alachlor during treatment. Our observations support the use of Fe0 for ex situ treatment of pesticide-contaminated soil.     

Origin and Distribution of Suspended Organic Matter As Inferred From Carbon Isotope Composition in A Mediterranean Semi-Enclosed Marine System

Abstract

The origin and distribution of suspended organic matter, the trophic features and the stable carbon isotopic composition of particulate organic carbon (POC) were studied monthly in a Western Mediterranean semi-enclosed basin. Sampling stations were selected as a function of wind-exposure and the degree of vegetation cover and then compared with an adjacent unvegetated site. the predominant vegetation was seagrass (Posidonia oceanica and Cymodocea nodosa) and Caulerpa prolifera. Water samples were analyzed for total suspended matter (inorganic and organic fractions), photosynthetic pigments (chlorophyll-a and phaeopigments), dissolved organic carbon, particulate organic carbon and their isotopic composition. Temperature and salinity were also measured at the same sampling sites within range of Mediterranean limits. the suspended organic matter concentration was 1.77 ± 1.55 mg l^?1; the chlorophyll-a concentration was low (0.35 ± 0.24 μg l^?1); the disolved organic carbon concentration was 2,140 ± 2,010 μg l^?1; the particulate organic carbon concentration was 212 ± 106 μg l^?1 and the isotopic composition was 18.77 ± 2.51%_°. There were significant temporal differences except for phaeopigments, POC and its POC isotopic composition, and there were no spatial differences other than for δ¹³C. This picture highlighted a general seasonal trend and trophical features similar to adjacent sea.

Spatial differences in δ¹³C showed that the source of suspended organic matter was different between stations as that between sources and wind-hydrodynamic constraints. In     

Quantification of metallothionein in whole body gammarus locusta (crustacea: amphipoda) using differential pulse polarography

A polarographic method was optimised for the quantitative determination of metallothionein (MT) in whole body Gammarus locusta (Crustacea: Amphipoda). The identity of the MT-like proteins was examined using electrophoretic analysis (SDS-PAGE) and induction studies (water-borne exposures to copper). The MT-method was then used to examine changes in MT levels over the lifetime (juveniles, sub-adults and adults) of a laboratory population of G. locusta; copper (Cu) and zinc (Zn) body burden were also measured by flame atomic absorption spectrometry. MT was quantified by heat-denaturation of 30?000?g supernatants (to remove the bulk of non-MT proteins) followed by differential pulse polarography (DPP) to measure sulphydryl-group containing proteins. DPP proved to be a sensitive and reliable method to quantify heat-stable total sulphydryl-proteins. The majority of the latter was indicated to be MT from SDS-PAGE and induction studies. SDS-PAGE revealed a putative MT of 23?±?0.6?kDa app. mol. wt., consistent with the average size of dimeric MTs (10–20?kDa) found in several aquatic invertebrate species. Copper-exposure revealed parallel increases in the amounts of 23?kDa protein and total sulphydryl-proteins. Levels of whole body MT (rabbit pure MT as standard) range between 1.3 and 2.3?mg?g^?1 dry wt. over the lifetime of G. locusta. Sex-related changes in MT status were observed, the levels in females being 1.6 times higher than in males (p<0.05). Copper and Zn body content changed over the lifetime of G. locusta, the levels in juveniles (p>0.05) and sub-adults (p<0.05) being higher than in adults. It is concluded that the inclusion of MT in ecotoxicological studies with amphipod crustaceans require some caution with respect to the stages of moulting and/or sexual maturation of organisms, but this should not provide any major impediment in its use in metal pollution monitoring.     

Effects of bisphenol A on Gammarus fossarum and Lumbriculus variegatus in artificial indoor streams

The impact of bisphenol A (BPA) on Gammarus fossarum and Lumbriculus variegatus was studied in four artificial indoor streams (0, 5, 50 and 500?µg?L^?1 BPA, nominal) over 103 days in a pulse–dose exposure scenario (weekly BPA application). For G. fossarum populations at day 103, the proportions of juveniles and of breeding females from the highest BPA treatment were in tendency reduced. For individually exposed gammarid pairs an EC₁₀ of 17?µg?L^?1 BPA (nominal) for the proportion of reproductive females in the fourth brood was determined. During the first three broods, the largest brood size occurred at the highest BPA concentration, whereas in the fourth brood it decreased concentration-dependently (fourth brood EC₁₀?=?5?µg?L^?1 BPA, nominal). Effects on L. variegatus were a reduced population growth (103?d-EC₁₀ of 2?µg?L^?1 BPA, nominal) and an increase in dry weight and the number of segments in large, complete worms.     

Carbofuran induced changes in breeding of a freshwater fish,Labeo rohita (Hamilton)

The effect of carbofuran, a carbamate pesticide, on the breeding performance of the freshwater fish Labeo rohita (Hamilton) has been investigated in the present study. Breeding of L. rohita was conducted after treatment with three sublethal concentrations, i.e. 0.06, 0.15 and 0.30 mg L^?1 of carbofuran for 96 h. The present investigation showed that the number of total eggs and total amount of eggs (litre per kg body weight) decreased significantly (p < 0.01) at all concentrations of carbofuran in comparison to controls, while the reduction in fertilization percentage at all concentrations of carbofuran was not significantly different from controls. The reduction in hatching percentage, the expected number of hatchlings, and the expected number of hatched larvae were significantly (p < 0.01) different between treated and control groups at all carbofuran concentrations. No significant differences for the 96 h survivability of hatched larvae were reported at all concentrations of carbofuran.     

Feasibility of metabolic parameter estimation in pharmacokinetic models of carbon tetrachloride exposure in rats1

Carbon tetrachloride (CCl₄) is a toxic chemical that was once used in degreasers and detergents, and some remnants of the chemical may be present in the water supply. Physiologically-based pharmacokinetic (PBPK) modeling can assist in understanding resulting internal doses of CCl₄ after exposure, but the pharmacokinetic parameters describing the metabolism of CCl₄ are not well characterized. The goal of this study was to provide insights into how to more accurately estimate these values in rats using PBPK modeling and data from previous studies. Three different PBPK models were constructed to describe CCl₄ exposure in rats via inhalation, oral ingestion, and venous injection. Each of these models was compared to data, and sensitivity analysis was performed for each model to determine whether the available data could be used to accurately determine the metabolic parameters of interest. These parameter sensitivities were so low that optimization to the available data yielded physiologically unrealistic results. Model sensitivities were analyzed for different doses and routes of exposure in order to find experimental conditions that would allow for greater identifiability of the metabolic parameters. Data were simulated from these models at optimal conditions with varying levels of noise from a normal distribution. Optimizations were then performed to confirm that the original values could be obtained. The experiments developed are left as suggestions for investigators who wish to further pursue estimating these metabolic parameters.