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101.
JITENDRA SINGH DILEEP K. SINGH 《Journal of environmental science and health. Part. B》2013,48(8):1305-1318
Impacts of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate), imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] and lindane (1,2,3,4,5.6-hexachlorocyclohexane) treatments on ammonium, nitrate, and nitrite nitrogen and nitrate reductase enzyme activities were determined in groundnut (Arachis hypogaea L.) field for three consecutive years (1997 to 1999). Diazinon was applied for both seed- and soil-treatments but imidacloprid and lindane were used for seed treatments only at recommended rates. Diazinon residues persisted for 60 days in both the cases. Average half-lives (t1/2) of diazinon were found 29.3 and 34.8 days respectively in seed and soil treatments. In diazinon seed treatment, NH4 +, NO3 ?, and NO2 ? nitrogen and nitrate reductase activity were not affected. Whereas, diazinon soil treatment indicated significant increase in NH4 +-N in a 1-day sample, which continued until 90 days. Some declines in NO3 ?N were found from 15 to 60 days. Along with this decline, significant increases in NO2 ?N and nitrate reductase activity were found between 1 and 30 days. Imidacloprid and lindane persisted for 90 and 120 days with average half-lives (t1/2) of 40.9 and 53.3 days, respectively. Within 90 days, imidacloprid residues lost by 73.17% to 82.49% while such losses for lindane residues were found 78.19% to 79.86 % within 120 days. In imidacloprid seed-treated field, stimulation of NO3 ?N and the decline in NH4 +NO2 ?-N and nitrate reductase enzyme activity were observed between 15 to 90 days. However, lindane seed treatment indicated significant increases in NH4 +-N, NO2 ?-N and nitrate reductase activity and some adverse effects on NO3 ?N between 15 and 90 days. 相似文献
102.
Louis P. Lue C.C. Lewis Veronica E. Melchor 《Journal of environmental science and health. Part. B》2013,48(3):343-354
Abstract Aldicarb, Temik® 15 G, was incorporated in furrows at 3.37 and 6.73 kg ai (active ingredent)/ha and carrots (Caucus carota L.) were directly seeded on the same day. The numbers of nematode larvae were significantly suppressed in the treated plots; averages were 249, 74, and 51/ 50 cc soil samples for control (0), 3.37 and 6.73 kg ai/ha, respectively. Aldicarb treatment resulted in a 28% yield increase as compared to the untreated. Aldicarb residue in carrots was 28 ppb for the low treatment and 46 ppb for the high. Residual levels in soil of high treatment declined from 6l to 31 ppb during two weeks prior to harvest, meanwhile, those in the low decreased slightly from 13 to 12 ppb. Carrots placed in hydroponic solution containing aldicarb 14.5 ppm for 6 days, had an aldicarb residue of 10.26 ppb and the hydroponic solution, 2.7 ppb. Persistence of aldicarb residue was in carrot > in soil > in hydroponic solution. 相似文献
103.
V. A. Romanenkov J. U. Smith P. Smith O. D. Sirotenko D. I. Rukhovitch I. A. Romanenko 《Regional Environmental Change》2007,7(2):93-104
The Model of Humus Balance was used to estimate the influence of climate effects and changing agricultural practices on carbon
(C) levels in soddy–podzolic soils in the Russian Federation for the years 2000–2050. The model was linked with a spatial
database containing soil, climate and farming management layers for identification of spatial change of C sequestration potential.
Analysis of relationships between C, soil texture and climate indicated that compared with a business-as-usual scenario, adaptation
measures could increase the number of polygons storing soil organic carbon (SOC) by 2010–2020. The rate of possible C loss
is sensitive to the different climate scenarios, with a maximum potential for SOC accumulation expected in 2030–2040, thereafter
decreasing to 2050. The effect is most pronounced for the arid part of the study area under the emission scenario with the
highest rate of increase in atmospheric CO2 concentration, supporting findings from the dynamic SOC model, RothC. C sequestration during the study period was permanent
for clay and clay loam soils with a C content of more than 2%, suggesting that C sequestration should be focused on highly
fertile, fine-textured soils. We also show that spatial heterogeneity of soil texture can be a source of uncertainty for estimates
of SOC dynamics at the regional scale.
Figures in color are available at 相似文献
104.
Jukka Lehto Jussi Paatero Reijo Pehrman Seija Kulmala Juhani Suksi Teija Koivula Timo Jaakkola 《Journal of environmental radioactivity》2008,99(10):1656
Lichen–soil column samples were taken from several locations in the Southern Finland between 1986 and 2006. Columns were divided into three parts, upper lichen, lower lichen and underlying soil, and their gamma emitting radionuclides, 134Cs, 137Cs, 103Ru, 95Zr, 106Ru, 110mAg, 125Sb and 144Ce, were measured with gamma spectrometry. Deposition values were calculated as Bq/m2 for each sampling site. Distribution of various radionuclides in the three compartments as a function of time was determined. Both effective and ecological half-lives of all radionuclides were calculated for upper lichen, whole lichen and whole lichen–soil column. A linear relation was derived between the physical half-lives and effective half-lives for whole lichen and for whole lichen–soil column. Reindeer meat activity concentrations of various radionuclides and ensuing radiation doses to reindeer-herding people were also estimated for a hypothetical case where a similar high radioactive pollution, as was taken place in the Southern Finland, would have occurred in the reindeer-herding areas in the Finnish Lapland. 相似文献
105.
介绍了广州市在用机动车抽检工作情况和程序,分析了排气抽检工作中存在的问题,提出了解决问题的建议和方法。 相似文献
106.
107.
Modeling Streamflow and Water Quality Sensitivity to Climate Change and Urban Development in 20 U.S. Watersheds 下载免费PDF全文
T. Johnson J. Butcher D. Deb M. Faizullabhoy P. Hummel J. Kittle S. McGinnis L.O. Mearns D. Nover A. Parker S. Sarkar R. Srinivasan P. Tuppad M. Warren C. Weaver J. Witt 《Journal of the American Water Resources Association》2015,51(5):1321-1341
Watershed modeling in 20 large, United States (U.S.) watersheds addresses gaps in our knowledge of streamflow, nutrient (nitrogen and phosphorus), and sediment loading sensitivity to mid‐21st Century climate change and urban/residential development scenarios. Use of a consistent methodology facilitates regional scale comparisons across the study watersheds. Simulations use the Soil and Water Assessment Tool. Climate change scenarios are from the North American Regional Climate Change Assessment Program dynamically downscaled climate model output. Urban and residential development scenarios are from U.S. Environmental Protection Agency's Integrated Climate and Land Use Scenarios project. Simulations provide a plausible set of streamflow and water quality responses to mid‐21st Century climate change across the U.S. Simulated changes show a general pattern of decreasing streamflow volume in the central Rockies and Southwest, and increases on the East Coast and Northern Plains. Changes in pollutant loads follow a similar pattern but with increased variability. Ensemble mean results suggest that by the mid‐21st Century, statistically significant changes in streamflow and total suspended solids loads (relative to baseline conditions) are possible in roughly 30‐40% of study watersheds. These proportions increase to around 60% for total phosphorus and total nitrogen loads. Projected urban/residential development, and watershed responses to development, are small at the large spatial scale of modeling in this study. 相似文献
108.
Paula Paíga Kaline Amaral Wanderley Severino Alves Júnior C.M. Delerue-Matos 《毒物与环境化学》2015,97(6):687-699
Carbamate compounds are an important group of cholinesterase inhibitors. There is a need for creating awareness regarding the risks of the inadequate carbamate use in the residential areas due to potential adverse human effects. Carbaryl is a commonly used pesticide worldwide. A simple, fast, and high-throughput method was developed employing liquid chromatography with fluorescence detector to determine carbaryl residues in rat feces. The extraction was performed by using a rapid, easy, cheap, effective, reliable, and safe (QuEChERS) method, using acetonitrile as the extracting solvent. The parameters for the performance of the extraction method were optimized, such as ratio of mass of sample per volume of extraction solvent, QuEChERS content, and cleanup columns. Linear response was obtained for all calibration curves (solvent and matrix-matched) over the established concentration range (5–500 μg/L) with a correlation coefficients higher than 0.999. The achieved recovery was 97.9% with relative standard deviation values of 1.1% (n = 4) at 167 μg/kg fortified concentration level and the limits of detection and quantification were 27.7 and 92.3 µg/kg, respectively. 相似文献
109.
Potassium silicate drilling fluids (PSDF) are a waste product of the oil and gas industry with potential for use in land reclamation. Few studies have examined the influence of PSDF on abundance and composition of soil bacteria and fungi. Soils from three representative locations for PSDF application in Alberta, Canada, with clay loam, loam and sand textures were studied with applications of unused, used once and used twice PSDF. For all three soils, applying ≥ 40 m3/ha of used PSDF significantly affected the existing soil microbial flora. No microbiota was detected in unused PSDF without soil. Adding used PSDF to soil significantly increased total fungal and aerobic bacterial colony forming units in dilution plate counts, and anaerobic denitrifying bacteria numbers in serial growth experiments. Used PSDF altered bacterial and fungal colony forming unit ratios of all three soils. 相似文献
110.
Ilaria Guagliardi Domenico Cicchell Rosanna De Ros Gabriele Buttafuoco 《环境科学学报(英文版)》2015,27(7):179-187
Exposure to lead (Pb) may affect adversely human health. Mapping soil Pb contents is essential to obtain a quantitative estimate of potential risk of Pb contamination. The main aim of this paper was to determine the soil Pb concentrations in the urban and peri-urban area of Cosenza–Rende to map their spatial distribution and assess the probability that soil Pb concentration exceeds a critical threshold that might cause concern for human health. Samples were collected at 149 locations from residual and non-residual topsoil in gardens, parks, flower-beds, and agricultural fields. Fine earth fraction of soil samples was analyzed by X-ray Fluorescence spectrometry. Stochastic images generated by the sequential Gaussian simulation were jointly combined to calculate the probability of exceeding the critical threshold that could be used to delineate the potentially risky areas. Results showed areas in which Pb concentration values were higher to the Italian regulatory values. These polluted areas were quite large and likely, they could create a significant health risk for human beings and vegetation in the near future. The results demonstrated that the proposed approach can be used to study soil contamination to produce geochemical maps, and identify hot-spot areas for soil Pb concentration. 相似文献