Determination of the residue dynamics and dietary risk of thiamethoxam and its metabolite clothianidin in citrus and soil by LC-MS/MS

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the determination of thiamethoxam and its metabolite clothianidin in citrus (including the whole citrus, peel and pulp) and soil samples by liquid chromatography-tandem mass spectrometry. The sample was extracted with acetonitrile and purified with octadecylsilane. The detection limits of both compounds were 0.0001–0.0002?mg kg^–1, while the limit of quantification of thiamethoxam was 0.002?mg kg^–1 and the limit of quantitation of metabolites was 0.001?mg kg^–1. The recovery was 70.37%–109.76%, with inter-day relative standard deviations (RSD) (n?=?15) values ≤9.46% for the two compounds in the four matrices. The degradation curve of thiamethoxam in whole citrus and soil was plotted using the first-order kinetic model. The half-life of the whole citrus was 1.9–6.2?days, and the half-life of the soil was 3.9–4.2?days. The terminal residue of thiamethoxam (the sum of thiamethoxam and clothianidin, expressed as thiamethoxam) was found to be concentrated on the peel. The final residual amount of thiamethoxam in the edible portion (pulp) was less than 0.061?mg kg^–1. The risk quotient values were all below 1, indicating that thiamethoxam as a citrus insecticide does not pose a health risk to humans at the recommended dosage.     

Bromide affecting drinking water mutagenicity

The effect of bromide on the mutagenicity of artificially recharged groundwater and purified artificially recharged groundwater after chlorine, ozone, hydrogen peroxide, permanganate, and UV treatments alone and in various combinations was studied. The highest mutagenicity was observed after chlorination, while hydrogen peroxide-ozone-chlorine treatment produced the lowest value for both waters. Chlorinated waters, which were spiked with bromide, had up to 3.7 times more mutagenic activity than waters without bromide after every preoxidation method. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to correspond as much as 76% of the overall mutagenicity in the waters not spiked with bromide. MX formation was found to be lower when the treated water contained bromide, implicating the formation of brominated MX analogues. Trihalomethane formation increased when the treated water contained bromide.     

Toxicity of chemical components of fine particles inhaled by aged rats: effects of concentration

This study tested the hypothesis that exposure to mixtures containing fine particles and ozone (O3) would cause pulmonary injury and decrements in functions of immunological cells in exposed rats (22-24 months old) in a dose-dependent manner. Rats were exposed to high and low concentrations of ammonium bisulfate and elemental carbon and to 0.2 ppm O3. Control groups were exposed to purified air or O3 alone. The biological end points measured included histopathological markers of lung injury, bronchoalveolar lung fluid proteins, and measures of the function of the lung's innate immunological defenses (macrophage antigen-directed phagocytosis and respiratory burst activity). Exposure to O3 alone at 0.2 ppm did not result in significant changes in any of the measured end points. Exposures to the particle mixtures plus O3 produced statistically significant changes consistent with adverse effects. The low-concentration mixture produced effects that were statistically significant compared to purified air but, with the exception of macrophage Fc receptor binding, exposure to the high-concentration mixture did not. The effects of the low- and high-concentration mixtures were not significantly different. The study supports previous work that indicated that particle + O3 mixtures were more toxic than O3 alone.     

Does the Harvard/U.S. Environmental Protection Agency Ambient Particle Concentrator change the toxic potential of particles?

Inhalation exposure to urban air particles is known to increase morbidity in humans and animals. Our group utilizes the Harvard/U.S. Environmental Protection Agency Ambient Particle Concentrator (HAPC) to generate concentrated aerosols of outdoor air particles for experimental exposures. We have reported increased pathologic responses to inhalation of concentrated urban air particles and identified silicon (as silicate) as an element associated with many of these responses. Using silicate-rich Mt. St. Helen's volcanic ash (MSHA), we exposed three groups of Sprague-Dawley rats by inhalation for 6 hr to filtered air, MSHA, or MSHA passed though the HAPC. Twenty-four hours following exposure, bronchoalveolar lavage was performed to assess total cell count, differential cell count, protein, lactate dehydrogenase, and n-beta-glucosaminidase levels. Peripheral blood was examined for packed cell volume, total protein, total white cells, and differential cell count. Morphologic studies localized particles in the lung and assessed pulmonary vasculature. No significant differences were observed among any of the groups in any parameter measured including morphometric analysis of pulmonary vasoconstriction. Scanning electron microscopy and X-ray analysis identified particles as silicates typical of MSHA throughout the lung. These findings suggest that particles passing through the HAPC have no change in their toxic potential in an exposure setting where particle deposition in the lung has occurred.     

Assessment of the potential for soil acidification in North India using the critical load approach and locally derived data for acidic and basic inputs

Major ions (Cl-, NO3(-), SO4(2-), Ca2+, Mg2+, Na+, K+ and NH4(+)) were analysed in wet and dry deposition samples collected for 2 years using a polyethylene bottle and funnel collector at Agra in India. The deposition of ionic components (Ca2+ and Mg2+) derived from natural sources i.e. soil were higher than those of anthropogenic origin. In rainwater samples, non-sea-salt fraction was found to be 60-90%. In both wet and dry deposition Ca2+ was found to be the dominant ion which may be due to its large particle diameter. Results suggest that most of the acidity, which occurs due to NO3(-), SO4(2-) and Cl- is neutralized by alkaline constituents, which originate from airborne local soil and dust transported from the Thar desert. Acid neutralizing capacity of soil has also been quantified and found to be 33 x 10(3) neqg(-1). Using deposition data, the critical load for acidity of soil with respect to Ashoka and Eucalyptus was evaluated. The present level of deposition of S and N was found to be much lower than critical loads calculated for S and N. Critical load of exceedance in terms of deposition acidity was also calculated and found to be negative. This indicates that with respect to these species, the ecosystem is protected at the current level of deposition.     

Environmental impacts of coastal aquaculture in eastern mediterranean bays the case of astakos gulf,Greece

GOAL, SCOPE AND BACKGROUND: Over the last decade Greece has become a leading country in the EU as concerns the cage farming of seabream and seabass. A strong debate has risen, however, about the environmental impacts of aquacultures in the coastal areas. The present paper deals with this problem and it is based on measurements of physico-chemical parameters in the water column, particulate matter and sediments in the area of Astakos Gulf, a coastal embayment in western Greece where three big fish farms are currently operating. METHODS: Water samples were collected by using Hydro-Bios sampling bottles, whereas a prototype sediment trap was installed under a fish cage for the collection of particulate matter. Temperature, dissolved oxygen, pH and salinity were measured in situ using portable equipment. Nutrients were determined by standard spectrophotometric methods. Trace metals were determined by Atomic Absorption Spectrometry. Dissolved organic carbon was determined by a Shimadzu 5000A carbon analyzer, whereas organic carbon in sediments was determined titrimetrically. RESULTS AND DISCUSSION: No clear eutrophication incidents have been identified, although the water column near the fish farms was enriched in nutrients and organic carbon. A sludge 'blanket' covers considerable parts of the seabed and is enriched in colloidal organic carbon and trace metals (Cd, Cu, Fe and Zn) that come from unused fish food. The biodegradation of this sludge leads to the development of anoxic conditions followed by the formation of undesirable gases, precipitation or remobilization of metals and the extinction of benthic fauna. CONCLUSION: The operation of fish farms at the coastal area of Astakos Gulf, and probably in similar Mediterranean gulfs, affects the marine environment, particularly in the vicinity of the cages. The most significant influence concerns the near-bottom water layer. The environmental impacts depend on the amount of food given to fishes, the mode of feeding, the fish density in cages, the annual production and the years of unit operation. The hydrology and the geomorphology of the area are also critical factors for its environmental quality. RECOMMENDATION AND OUTLOOK: The success of the fish-farming sector in the Mediterranean is accompanied by environmental and, in some extents, by social and marketing problems. These problems, derived from the rapid development of fish farming, can be solved only through an integrated management, using methods such as environmental impact assessment, risk assessment, economic evaluation, vulnerability assessments, resource accounting, cost-benefit analysis and outcome-based monitoring.     

Trimethylbenzoic acids as metabolite signatures in the biogeochemical evolution of an aquifer contaminated with jet fuel hydrocarbons

Evolution of trimethylbenzoic acids in the KC-135 aquifer at the former Wurtsmith Air Force Base (WAFB), Oscoda, MI was examined to determine the functionality of trimethylbenzoic acids as key metabolite signatures in the biogeochemical evolution of an aquifer contaminated with JP-4 fuel hydrocarbons. Changes in the composition of trimethylbenzoic acids and the distribution and concentration profiles exhibited by 2,4,6- and 2,3,5-trimethylbenzoic acids temporally and between multilevel wells reflect processes indicative of an actively evolving contaminant plume. The concentration levels of trimethylbenzoic acids were 3-10 orders higher than their tetramethylbenzene precursors, a condition attributed to slow metabolite turnover under sulfidogenic conditions. The observed degradation of tetramethylbenzenes into trimethylbenzoic acids obviates the use of these alkylbenzenes as non-labile tracers for other degradable aromatic hydrocarbons, but provides rare field evidence on the range of high molecular weight alkylbenzenes and isomeric assemblages amenable to anaerobic degradation in situ. The coupling of actual tetramethylbenzene loss with trimethylbenzoic acid production and the general decline in the concentrations of these compounds demonstrate the role of microbially mediated processes in the natural attenuation of hydrocarbons and may be a key indicator in the overall rate of hydrocarbon degradation and the biogeochemical evolution of the KC-135 aquifer.     

Emission and fate assessment of methyl tertiary butyl ether in the Boston area airshed using a simple multimedia box model: comparison with urban air measurements

Expected urban air concentrations of the gasoline additive methyl tertiary butyl ether (MTBE) were calculated using volatile emissions estimates and screening transport models, and these predictions were compared with Boston, MA, area urban air measurements. The total volatile flux of MTBE into the Boston primary metropolitan statistical area (PMSA) airshed was calculated based on estimated automobile nontailpipe emissions and the Universal Quasi-Chemical Functional-Group Activity Coefficient computed abundance of MTBE in gasoline vapor. The fate of MTBE in the Boston PMSA was assessed using both the European Union System for the Evaluation of Substances, which is a steady-state multimedia box model, and a simple airshed box model. Both models were parameterized based on the meteorological conditions observed during air sampling in the Boston area. Measured average urban air concentrations of 0.1 and 1 microg/m3 MTBE during February and September of 2000, respectively, were comparable to corresponding model predictions of 0.3 and 1 microg/m3 and could be essentially explained from estimated temperature-dependent volatile emissions rates, observed average wind speed (the airshed flushing rate), and reaction with ambient tropospheric hydroxyl radical (*OH), within model uncertainty. These findings support the proposition that one can estimate gasoline component source fluxes and use simple multimedia models to screen the potential impact of future proposed gasoline additives on urban airsheds.     

Real-time indoor and outdoor measurements of black carbon in an occupied house: an examination of sources

Black carbon (BC) was measured every 5 min for two years (May 1998-May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two aethalometers, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.53 in the first year and 0.35 in the second year. The main outdoor source of BC was the general regional background, contributing 83-84% of the total during each of the two years. Morning rush hour traffic contributed 8-9% of the total BC. An evening peak in the fall and winter, thought to include contributions from wood burning, was responsible for approximately 8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16 and 31%, respectively, of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor aethalometer in both years. An artifact associated with the tape advance was noted for the aethalometer, but a correction factor was developed that reduced the associated error by a factor of 2.