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201.
Gyps vultures across India are declining rapidly and the NSAID diclofenac has been shown to be the major cause. Vultures scavenge livestock carcasses that have been treated with diclofenac within the days preceding death. We present data on diclofenac disposition in Indian cow and goat, and field data on the prevalence of diclofenac in carcases in the environment. In the disposition experiment, animals were treated with a single intramuscular injection of diclofenac at 1000 microg kg-1 bw. In cow, diclofenac was detectable in liver, kidney and intestine up to 71 h post-treatment; in plasma, half-life was 12.2 h. In goat, tissue residues were undetectable after 26 h. Prevalence of diclofenac in liver from 36 dead livestock collected in the field was 13.9%. Data suggest that diclofenac residues in Indian cow and goat are short-lived, but diclofenac prevalence in carcasses available to vultures may still be very high.  相似文献   
202.
The occurrence of enteric viruses in reclaimed wastewater, their removal by efficient treatment processes and the public health hazards associated with their release into the environments are of great significance in environmental microbiology. In this study, TaqMan-based real-time polymerase chain reaction (qPCR) was used to assess the prevalence of human adenovirus (HAdV), rotavirus (RV) and hepatitis A virus (HAV) in the final effluents of two wastewater treatment plants in the Eastern Cape Province, South Africa, over a twelve-month sampling period. The correlation between the concentrations of viruses in the effluents samples and faecal coliform (FC) densities were assessed as to validate the use of FC as microbiological indicator in water quality assessment. HAdV was detected in 62.5 % (30/48) of the samples with concentrations ranging between 8.4 × 101 and 1.0 × 105 genome copies/L while HAV and RV were only detected at concentrations below the set detection limits. FCs densities ranged from 1 to 2.7 × 104 CFU/100 ml. Adenovirus species HAdV-B (serotype 2) and HAdV-F (serotype 41) were detected in 86.7 % (26/30) and 6.7 % (2/30) of the HAdV-positive samples, respectively. No consistent seasonal trend was observed in HAdV concentrations, however, increased concentrations of HAdV were generally observed in the winter months. Also, there was no correlation between the occurrence of HAdV and FC at both the treatment plants. The persistent occurrence of HAdV in the discharged treated effluents points to the potential public health risk through the release of HAdV into the receiving watersheds, and the possibility of their transmission to human population.  相似文献   
203.
In recent decades, public and private environmental entities have been purchasing or leasing water rights across the Western United States (U.S.) in efforts to restore river flows and aquatic ecosystems. The need to pay for flow restoration arises from the fact that state governments did not begin to reserve water for instream purposes until the 1970s, long after water rights had become over‐appropriated and flows were substantially depleted in most rivers. As a consequence, flow depletion has become the leading cause of fish endangerment in the U.S., including the imperilment of two‐thirds of all native fish species in the Colorado River system. This paper takes stock of the progress made in buying water for the environment, specifically by reviewing and analyzing more than 50 transactions executed by public and private entities and the sources of funding underpinning these transactions. We conclude that nongovernmental actors — such as environmental organizations and state water trusts — are integral to regional efforts to restore river flows; these nongovernmental actors executed more than two‐thirds of the transactions we documented. However, we also conclude that the long‐term success of these nongovernmental actors depends upon the availability of sustained public funding that enables them to build capacity and engage in the large number of transactions needed to restore flows across each state.  相似文献   
204.
Bastos PM  Eriksson J  Green N  Bergman A 《Chemosphere》2008,70(7):1196-1202
The term persistence has been used to confusion since it is used as a conceptual parameter without a uniform definition. Work is therefore being done in order to unite ideas and describe persistence based on the chemical reactivity and chemico-physical properties of compounds via investigation of the main degradation pathways in the environment; photolysis, hydrolysis-substitution-elimination (hse), oxidation, reduction and radical reactions. The present work is focused on developing a method to determine oxidative degradation rates of chemicals and thereby measurement of their susceptibility to undergo oxidation reactions. The method based on potassium permanganate works well for water soluble compounds and is easy, robust, inexpensive and reproducible. By using the method and varying the analysed substances, the degradation rates for brominated phenols, two chlorinated phenols and high volume production compounds such as tetrabromobisphenol A (TBBPA), tetrachlorobisphenol A (TCBPA) and bisphenol A (BPA) have been determined at pH 7.6+/-0.2. The reaction rates of the two halogenated BPA's are particularly fast, giving half-lives in seconds. The other test compounds have slower reaction rates but easily measured under the reaction conditions applied. The reactions are temperature dependent. There is evidence that pK(a) and the substitution pattern of the halogens affects the rate of the reactions. The method is robust and applicable for reaction rate constant measurements of present and potential future environmental contaminants.  相似文献   
205.
Hwang HM  Green PG  Young TM 《Chemosphere》2008,71(11):2139-2149
To assess potential health risks to benthic organisms from exposure to toxic contaminants, sediment chemistry data from five salt marshes along the coast of California were compared with threshold effects levels (TELs) and probable effects levels (PELs). As an integrated estimate of toxicity potential of multiple contaminants, mean PEL quotients (mPELQs) were used to categorize sampling stations into three groups: high (>0.5), medium (0.1–0.5) and low (<0.1). In all sediments from Stege Marsh located in San Francisco Bay, at least one contaminant exceeded PELs by up to 18-fold and mPELQs were higher than 0.7. Mean PELQs in two core sediments from eastern Stege Marsh ranged from 0.7 to 2.1, indicating that benthic organisms in Stege Marsh may have been adversely affected for several decades. To investigate bioavailability and bioaccumulation of contaminants in sediments, longjaw mudsuckers (Gillichthys mirabilis) were transplanted to six Stege Marsh stations for 60 days. Body burdens of organic contaminants clearly showed that they were readily available for benthic organisms. Measured concentrations of organic contaminants in mudsuckers were similar to estimated levels computed using a theoretical bioaccumulation potential model. Levels of PCBs and arsenic in mudsuckers were higher than screening values set as guidelines for the protection of humans and levels of PCBs and DDTs were higher than criteria for wildlife. The results of this study indicate that the levels of contaminants in Stege Marsh sediments may not fully support the well-being of benthic organisms and also may provoke adverse effects on fish-eating animals and humans through trophic transfer.  相似文献   
206.
Medina playa lake, a Ramsar site in western Andalusia, is a brackish lowland lake of 120 ha with an average depth of 1 m. Water flows into Medina from its 1,748-ha watershed, but the hydrology of the lake has not previously been studied. This paper describes the application of a water budget model on a monthly scale over a 6-year period, based on a conceptual hydrological model, and considers different future scenarios after calibration to improve the understanding of the lake’s hydrological functioning. Climatic variables from a nearby weather station and observational data (water-level evolution) were used to develop the model. Comparison of measured and predicted values demonstrated that each model component provided a reasonable output with a realistic interaction among the components. The model was then used to explore the potential consequences of land-use changes. Irrigation of olive groves would significantly reduce both the hydroperiod (becoming dry 15% of the time) and the average depth of the lake (water level <0.5 m 40% of the time). On the other hand, removal of an artificial overflow would double the average flooded surface area during high-water periods. The simulated water balance demonstrates that the catchment outputs are dominated by lake evaporation and surface outflow from the lake system to a creek. Discrepancies between predicted and observed water levels identify key areas of uncertainty for future empirical research. The study provides an improved basis for future hydrological management of the catchment and demonstrates the wider utility of this methodology in simulating this kind of system. This methodology provides a realistic appraisal of potential land-use management practices on a catchment-wide scale and allows predictions of the consequences of climate change.  相似文献   
207.
Traditional methods of assessing fungal exposure have been confounded by a number of limiting variables. The recent utilization of molecular methods such as internal transcribed spacer (ITS) sequencing of ribosomal RNA genes has provided improved insight into the diversity of fungal bioaerosols in indoor, outdoor and occupational environments. However, ITS analyses may also be confounded by a number of methodological limitations. In this study, we have optimized this technology for use in occupational or environmental studies. Three commonly used DNA extraction methodologies (UltraClean Soil kit, High Pure PCR Template kit, and EluQuik/DNeasy kit) were compared in terms of sensitivity and susceptibility to PCR inhibitors in dust for three common fungal bioaerosols, Aspergillus versicolor, Rhizopus microsporus and Wallemia sebi. Environmental dust samples were then studied using each extraction methodology and results were compared to viable culture data. The extraction methods differed in terms of their ability to efficiently extract DNA from particular species of fungi (e.g. Aspergillus versicolor). In addition, the ability to remove PCR inhibitors from dust samples was most effective using the soil DNA extraction kit. The species composition varied greatly between ITS clone libraries generated with the different DNA extraction kits. However, compared to viable culture data, ITS clone libraries included additional fungal species that are incapable of growth on solid culture medium. Collectively, our data indicated that DNA extraction methodologies used in ITS sequencing studies of occupational or environmental dust samples can greatly influence the fungal species that are detected.  相似文献   
208.
Thirty cases of cervical cystic hygroma were diagnosed in the first trimester of pregnancy. Karyotype analysis was available in 29 (97 per cent). Fifteen (52 per cent) had a chromosomal abnormality. The ultrasound appearance was described as posterior cervical, lateral cervical, or cervical hygroma with hydrops. Of the 14 euploid embryos, six were electively aborted, two are undelivered, and six have been delivered as phenotypically normal infants. In cases in which the chromosomes were normal and the pregnancy continued, all lesions resolved by 18 weeks.  相似文献   
209.
Abstract

A simple data analysis method called the Tracer-Aerosol Gradient Interpretive Technique (TAGIT) is used to attribute particulate S and SO2 at Big Bend National Park in Texas and nearby areas to local and regional sources. Particulate S at Big Bend is of concern because of its effects on atmospheric visibility. The analysis used particulate S, SO2 , and perfluorocarbon tracer data from six 6-hr sampling sites in and near Big Bend National Park. The data were collected in support of the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study; the field portion was conducted from July through October 1999. Perfluorocarbon tracer was released continuously from a tower at Eagle Pass, TX, approximately 25 km northeast of two large coal-fired power plants (Carbon I and II) in Coahuila, Mexico, and approximately 270 km east-southeast of Big Bend National Park.

The perfluorocarbon tracer did not properly represent the location of the emissions from the Carbon power plants for individual 6-hr sampling periods and attributed only 3% of the particulate S and 27% of the SO2 at the 6-hr sites in and near Big Bend to sources represented by the tracer. An alternative approach using SO2 to tag “local” sources such as the Carbon plants attributed 10% of the particulate S and 75% of the SO2 at the 6-hr sites to local sources. Based on these two approaches, most of the regional (65–86%) and a small fraction (19–31%) of the local SO2 was converted to particulate S. The analysis implies that substantial reductions in particulate S at Big Bend National Park cannot be achieved by only reducing emissions from the Carbon power plants; reduction of emissions from many sources over a regional area would be necessary.  相似文献   
210.
ABSTRACT

Project MOHAVE was a major monitoring, modeling, and data analysis study whose objectives included the estimation of the contributions of the Mohave Power Project (MPP) and other sources to visibility impairment in the southwestern United States, in particular at Grand Canyon National Park. A major element of Project MOHAVE was the release of perfluorocarbon tracers at MPP and other locations during 50-day summer and 30-day winter intensive study periods. Tracer data (from about 30 locations) were sequestered until several source and receptor models were used to predict tracer concentrations. None of the models was successful in predicting the tracer concentrations; squared correlation coefficients between predicted and measured tracer were all less than 0.2, and most were less than 0.1.  相似文献   
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