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171.
M. W. Kress R. Baker S. J. Ursic 《Journal of the American Water Resources Association》1990,26(5):747-756
ABSTRACT: The deposition and chemistry of precipitation were estimated for one year in two forest ecosystems in the South-Central United States. Precipitation, throughfall, litter leachate, and soil leachate were analyzed for a small catchment of pine-hardwoods in southeastern Oklahoma and for a catchment of loblolly pines (Pinus taeda L.) in northern Mississippi. In the pine-hardwood forest, 98 percent of the acid deposition was neutralized, 50 percent in the forest canopy, and 48 percent in the forest floor. In the pine forest, 75 percent of the acid deposition was neutralized, all in the forest floor. The pine-hardwood ecosystem accumulated sulfate, nitrate, and ammonia ions, and lost base cations. During seasons of deficient precipitation, dry deposition appeared to enrich the concentrations of hydrogen, nitrate, sulfate, and ammonia ions in throughfall samples at both locations. 相似文献
172.
Wendy A. Rice Steven M. Gorelick 《Journal of the American Water Resources Association》1985,21(6):919-930
A graphical inverse method for determining the regional transmissivity distribution was applied to three field problems. The study areas were the Hanford Site, Washington; the Rocky Mountain Arsenal, Colorado; and the Nevada Test Site, Nevada. This method can aid in flow system conceptualization by revealing the location of bedrock controls for groundwater flow. It is a valuable tool for aiding the hydrogeologist in asking questions about the nature of trends in the pattern of transmissivity values. Quantitative estimates of regional transmissivities can be used as starting points for further parameter refinement. Sensitivity analysis using Monte Carlo simulation shows that quantitative estimates of transmissivity can be obtained when measurement error in the hydraulic head does not cause a large error in the hydraulic gradient. 相似文献
173.
Mary Beth Adams James N. Kochenderfer Pamela J. Edwards 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):267-273
In 1989, a watershed acidification experiment was begun on the Fernow Experimental Forest in West Virginia, USA. Ammonium
sulfate fertilizer (35.5 kg N ha−1 yr−1and 40.5 kg S ha−1 yr−1) was applied to a forested watershed (WS3) that supported a 20-year-old stand of eastern deciduous hardwoods. Additions of
N and S are approximately twice the ambient deposition of nitrogen and sulfur in the adjacent mature forested watershed (WS4),
that serves as the reference watershed for this study. Acidification of stream water and soil solution was documented, although
the response was delayed, and acidification processes appeared to be driven by nitrate rather than sulfate. As a result of
the acidification treatment, nitrate solution concentrations increased below all soil layers, whereas sulfate was retained
by all soil layers after only a few years of the fertilization treatments, perhaps due to adsorption induced from decreasing
sulfate deposition. Based on soil solution monitoring, depletion of calcium and magnesium was observed, first from the upper
soil horizons and later from the lower soil horizons. Increased base cation concentrations in stream water also were documented
and linked closely with high solution levels of nitrate. Significant changes in soil chemical properties were not detected
after 12 years of treatment, however. 相似文献
174.
气相色谱法测定水和废水中丙烯腈 总被引:2,自引:0,他引:2
本文通过采用气相色谱法,以GDX-502为固定相,FID为检测器测定水和废水中的丙烯腈,精密度和回收率高.方法简便易行,能满足行业废水和地面水的监队是水和废水中丙烯腈分析的较理想方法。 相似文献
175.
气相色谱测定土壤中微量阿特拉津 总被引:6,自引:0,他引:6
采用丙酮加水提取土壤中的阿特拉津,再用三氯甲烷萃取,经浓缩、定容后,用毛细管气相色谱法测定. 相似文献
176.
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
177.
The efficiency of water rinsing for removing fenthion from non-combustible used pesticide containers was investigated. Four hundred empty containers from four olive oil producing areas in Greece were studied. Following triple rinsing cleaning procedures, the amount of fenthion retained in the container ranged from 0.01% to 0.1% w/w of its initial concentration. Extraction was accomplished with acetone, and the extracts were analyzed with a capillary gas chromatographic system coupled with flame ionization detector. The results obtained showed that triple rinsing is an effective procedure for removing fenthion from used pesticide containers, since the remaining pesticide concentration was below the legislated threshold value. Consequently, the containers can be handled as non-hazardous solid wastes. 相似文献
178.
建立了测定工业废水中乙醇和异丙醇的顶空毛细管气相色谱法.采用顶空进样技术,分析过程不使用有机试剂,避免了对分析人员和环境的危害.乙醇和异丙醇在3.00~ 20.0mg/L浓度范围内呈良好线性关系,水样测定结果重现性较好,相对标准偏差范围均小于2%,乙醇加标回收率为93.6%~104.0%,异丙醇加标回收率为94.0%~ 102.0%.本方法操作简单快速,灵敏度高,能满足工业废水中乙醇和异丙醇的监测. 相似文献
179.
180.
研究了固相膜萃取对地表水中有机氯农药(OCPs)物质的提取效果,并与液液提取法(LLE)进行比较.建立了固相膜萃取/气相色谱法检测地表水中20种有机氯农药的方法.结果表明:当萃取膜为HLB膜,洗脱液溶剂为丙酮和正己烷,萃取效果最理想,20种OCPs的回收率稳定在74.1%~94.3%之间,固相膜萃取法与传统液液提取法相比,既提高了萃取效率同时又减少了有机萃取溶剂的用量.该法检测实际样品时,同时加入2种内标指示剂对方法的性能进行了验证,2种内标示踪剂的回收率分别为71.6%~94.8%和69.9%~109.5%,样品中20种OCPs均未检出. 相似文献