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221.
Pyrethroid insecticides are hydrophobic compounds that partition to streambed sediments and have been shown to cause toxicity to non-target organisms; their occurrence is well documented in parts of California, but there have been limited studies in other urban and agricultural areas across the United States. To broaden geographic understanding of pyrethroid distributions, bed sediment samples were collected and analyzed from 36 streams in 25 states, with about 2/3 of the sites in urban areas and 1/3 in agricultural areas. At least one pyrethroid (of the 14 included in the analysis) was detected in 78% of samples. Seven pyrethroids were detected in one or more samples. Bifenthrin was the most frequently detected (58% of samples), followed by permethrin (31%), resmethrin (17%), and cyfluthrin (14%). The other three detected pyrethroids (cyhalothrin, cypermethrin and delta/tralomethrin) were found in two or fewer of the samples. Concentrations ranged from 0.3 to 180 ng g(-1) dry weight. The number of pyrethroids detected were higher in the urban samples than in the agricultural samples, but the highest concentrations of individual pyrethroids were split between urban and agricultural sites. The pyrethroids detected in the agricultural areas generally followed use patterns. Predicted toxicity was greater for urban areas and attributed to bifenthrin, cyfluthrin and cypermethrin, while in agricultural areas the toxicity was mainly attributed to bifenthrin. 相似文献
222.
Evaluation of surface water quality in aquatic bodies under the influence of uranium mining (MG, Brazil) 总被引:1,自引:0,他引:1
Suzelei Rodgher Heliana de Azevedo Carla Rolim Ferrari Cláudio Vítor Roque Leilane Barbosa Ronqui Michelle Burato de Campos Marcos Roberto Lopes Nascimento 《Environmental monitoring and assessment》2013,185(3):2395-2406
The quality of the water in a uranium-ore-mining area located in Caldas (Minas Gerais State, Brazil) and in a reservoir (Antas reservoir) that receives the neutralized acid solution leaching from the waste heaps generated by uranium mining was investigated. The samples were collected during four periods (October 2008, January, April and July 2009) from six sampling stations. Physical and chemical analyses were performed on the water samples, and the data obtained were compared with those of the Brazilian Environmental Standards and WHO standard. The water samples obtained from waste rock piles showed high uranium concentrations (5.62 mg L?1), high manganese values (75 mg L?1) and low average pH values (3.4). The evaluation of the water quality at the point considered the limit between the Ore Treatment Unit of the Brazilian Nuclear Industries and the environment (Consulta Creek) indicated contamination by fluoride, manganese, uranium and zinc. The Antas reservoir showed seasonal variations in water quality, with mean concentrations for fluoride (0.50 mg L?1), sulfate (16 mg L?1) and hardness (20 mg L?1) which were low in January, evidencing the effect of rainwater flowing into the system. The concentrations for fluoride, sulfate and manganese were close or above to the limits established by current legislation at the point where the treated mining effluent was discharged and downstream from this point. This study demonstrated that the effluent discharged by the UTM affected the quality of the water in the Antas reservoir, and thus the treatments currently used for effluent need to be reviewed. 相似文献
223.
Michelle M. Patterson Ginger B. Paige Katta J. Reddy 《Environmental monitoring and assessment》2010,171(1-4):267-280
High selenium (Se) concentrations have been found in surface waters in the Kendrick Reclamation Project, Wyoming. Precipitation and irrigation water moving over seleniferous soils are contributing causes, and drought may exacerbate this. This study surveyed Se concentrations and discharges in local surface streams, irrigation drains, and the delivery canal. Sites were sampled monthly and analyzed for Se and total suspended solids (TSS). A completely randomized design with two factors (soil parent material and location, inside or outside irrigation district) was used. Mean Se concentrations were 64 μg L???1 inside the irrigation district on shale soils, 17 μg L???1 inside the district off shale soils, 5 μg L???1 outside the district on shale soils, and 3 μg L???1 outside the district off shale soils. Correlations between discharge and Se concentrations were generally negative, while correlations between discharge and Se load were generally positive. There was little correlation between load and concentration, and little correlation between TSS and Se. A comparison of Se concentrations in streams and drains showed Se concentrations were significantly higher (p?<?0.001) in streams during the irrigation season, but not in the off-season (p?=?0.515). We conclude that higher discharges decrease Se concentration, but increase load. Conversion from flood to sprinkle irrigation may increase Se concentrations by reducing discharge, but decrease Se loads going into the N. Platte River, and will likely alter the timing and magnitude of flows. Both load and concentration should be considered when implementing Se regulations and standards. 相似文献
224.
225.
We developed and tested a theory of the relationship between merit pay raises and organization‐based self‐esteem (OBSE) in a longitudinal study of hospital employees. We predicted that the positive relationship between merit pay raise size and OBSE would be stronger when pay‐for‐performance (PFP) perceptions were high and predicted further that this interaction would be stronger among older employees. As predicted, merit pay raises were not related to OBSE levels for younger employees, but, among older employees, larger merit raises increased OBSE when PFP perceptions were high and decreased OBSE when PFP perceptions were low. Implications of the study for merit pay theory and practice are addressed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
226.
Lori E. Apodaca Jeffrey B. Bails C. Michelle Smith 《Journal of the American Water Resources Association》2002,38(1):133-149
ABSTRACT: Shallow ground water in areas of increasing urban development within the Upper Colorado River Basin was sampled for inorganic and organic constituents to characterize water‐quality conditions and to identify potential anthropogenic effects resulting from development. In 1997, 25 shallow monitoring wells were installed and sampled in five areas of urban development in Eagle, Grand, Gunnison, and Summit Counties, Colorado. The results of this study indicate that the shallow ground water in the study area is suitable for most uses. Nonparametric statistical methods showed that constituents and parameters measured in the shallow wells were often significantly different between the five developing urban areas. Radon concentrations exceeded the proposed USEPA maximum contaminant level at all sites. The presence of nutrients, pesticides, and volatile organic compounds indicate anthropogenic activities are affecting the shallow ground‐water quality in the study area. Nitrate as N concentrations greater than 2.0 mg/L were observed in ground water recharged between the 1980s and 1990s. Low concentrations of methylene blue active substances were detected at a few sites. Total coliform bacteria were detected at ten sites; however, E. coli was not detected. Continued monitoring is needed to assess the effects of increasing urban development on the shallow ground‐water quality in the study area. 相似文献
227.
Jiuli Yang Mingyang Liu Qu Cheng Lingyue Yang Xiaohui Sun Haidong Kan Yang Liu Michelle L. Bell Rohini Dasan Huiwang Gao Xiaohong Yao Yang Gao 《Frontiers of Environmental Science & Engineering》2022,16(5):56
228.
One adverse consequence of interpersonal mistreatment is that it damages the relationship between the victim and the transgressor. Scholars have promoted forgiveness of such mistreatment as a victim response that can motivate transgressors to work towards relationship restoration. Building on social exchange theory and the social perception literature, we provide an account of when transgressors are less (vs. more) willing to restore their relationship with the victim in response to forgiveness. Specifically, we argue that transgressors perceive forgiveness from a victim who has high (vs. low) power, relative to the transgressor, as insincere, making transgressors less willing to restore the relationship. We further argue that this effect of high (vs. low) victim power is pronounced especially when the victim also has low (vs. high) status. Two experiments and two field studies support these predictions. These findings highlight the relevance of studying how contextual conditions color transgressors' perceptions of victims' behavior to understand relationship restoration after interpersonal mistreatment. 相似文献
229.
Michelle A. Mycoo 《Regional Environmental Change》2018,18(8):2341-2353
Global warming of 1.5 °C above preindustrial levels and a commensurate increase in global greenhouse gas emissions pose an unprecedented danger to human settlements, livelihoods and the sustainable development of Small Island Developing States (SIDS), yet these challenges present tremendous opportunities to rethink development pathways. The paper has two objectives. One is to critically review present vulnerabilities and adaptation strategies employed by the state, private sector, non-governmental organisations, community-based organisations and households. The other is to discuss vulnerabilities and identify adaptation and resiliency strategies which are considered most applicable beyond the 1.5 °C limit. The Caribbean Region is the focus of the paper. A key finding of the paper is that temperature change above the 1.5 °C limit set by the Paris Conference of the Parties will make the natural and human systems of SIDS even more highly vulnerable than they are already. Another finding is that Caribbean states have implemented various innovative climate change adaptation strategies, but their relevance should the 1.5 °C target be exceeded, requires further exploration. The paper is useful to policymakers, decision-makers and finance agencies in search of practical solutions to avert the implications for Caribbean settlements, economies and ecosystems should the temperature warming exceed 1.5 °C. 相似文献
230.
There is a critical need for highly sensitive, cost-effective sensors to conduct ecological analyses for environmental and homeland security-related applications. Enzyme biosensors, which are currently gaining acceptance for environmental monitoring applications, need improvements to deliver faster measurements with stabilized sensing elements, e.g., enzymes. We report here on a method which significantly overcomes this difficulty, and demonstrate its application in a biosensor for aquatic environmental applications. A fast-responding and stable biosensor was developed via immobilization of organophosphorus hydrolase (OPH) in functionalized mesoporous silica (FMS) with pore sizes in tens of nanometers. The OPH-FMS composite was held on glassy carbon electrode by a dried Nafion gel and FMS protected OPH from Nafion-resulted activity loss. The resulting enzyme biosensor, when integrated with an electrochemical instrument, responded rapidly to low paraoxon concentration and achieved steady-state current in less than 10 s, with a detection limit of 4.0x10(-7) M paraoxon. The biosensor was tested for detection of paraoxon in simulated environmental samples, under wide-ranging physicochemical conditions. Results clearly indicate high recovery efficiencies in aqueous solutions (96 to 101%) at different pH, total organic carbon, total dissolved solids, and total suspended solids, and demonstrate the ability of the biosensor unit to continuously monitor paraoxon in aqueous conditions similar to those found in river and lake systems. 相似文献