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991.
Creed I. F. Trick C. G. Band L. E. Morrison I. K. 《Water, Air, & Soil Pollution: Focus》2002,2(1):81-102
There is considerable spatial heterogeneity in organic carbon (C), total nitrogen (N), and potentially mineralizable nitrogen (PMN) pools in the soils of the Turkey Lakes Watershed. We hypothesized that topography regulates the spatial pattern of these pools through a combination of static factors (slope, aspect and elevation), which influence radiation, temperature andmoisture conditions, and dynamic factors (catenary position,profile and planar curvature), which influence the transport ofmaterials downslope. We used multiple linear regression (MLR)and tree regression (TR) models as exploratory techniques todetermine if there was a topographic basis for the spatialpattern of the C, N and PMN pools. The MLR and TR modelspredicted similar integrated totals (i.e., within 5% of eachother) but dissimilar spatial patterns of the pools. For thecombined litter, fibric and hemic layer, the MLR models explaineda significant portion of the variance (R2 = 0.38, 0.23 and0.28 for C, N and PMN, respectively), however, the residuals werelarge and biased (the smallest contents were over-predicted andthe largest contents were under-predicted). The TR models (9-branch), in contrast, explained a greater portion of the variance (R2 = 0.75, 0.67 and 0.62 for C, N and PMN, respectively) and the residuals were smaller and unbiased. Based on our sampling strategy, the models suggested that static factors were most important in predicting the spatial pattern of the nutrient pools. However, a nested sampling strategy that included scales where both static (among hillslopes) and dynamic (within hillslope) factors result in a systematic variation in soil nutrient pools may have improvedthe predictive ability of the models. 相似文献
992.
Lauren E. Hay Gregory J. McCabe 《Journal of the American Water Resources Association》2002,38(3):847-860
ABSTRACT: A monthly water‐balance (WB) model was tested in 44 river basins from diverse physiographic and climatic regions across the conterminous United States (U.S.). The WB model includes the concepts of climatic water supply and climatic water demand, seasonality in climatic water supply and demand, and soil‐moisture storage. Exhaustive search techniques were employed to determine the optimal set of precipitation and temperature stations, and the optimal set of WB model parameters to use for each basin. It was found that the WB model worked best for basins with: (1) a mean elevation less than 450 meters or greater than 2000 meters, and/or (2) monthly runoff that is greater than 5 millimeters (mm) more than 80 percent of the time. In a separate analysis, a multiple linear regression (MLR) was computed using the adjusted R‐square values obtained by comparing measured and estimated monthly runoff of the original 44 river basins as the dependent variable, and combinations of various independent variables [streamflow gauge latitude, longitude, and elevation; basin area, the long‐term mean and standard deviation of annual precipitation; temperature and runoff; and low‐flow statistics (i.e., the percentage of months with monthly runoff that is less than 5 mm)]. Results from the MLR study showed that the reliability of a WB model for application in a specific region can be estimated from mean basin elevation and the percentage of months with gauged runoff less than 5 mm. The MLR equations were subsequently used to estimate adjusted R‐square values for 1,646 gauging stations across the conterminous U.S. Results of this study indicate that WB models can be used reliably to estimate monthly runoff in the eastern U.S., mountainous areas of the western U.S., and the Pacific Northwest. Applications of monthly WB models in the central U.S. can lead to uncertain estimates of runoff. 相似文献
993.
994.
1IntroductionNowadays,asthenaturalresourcesbecomemoreandmorelimitedtotheeconomicdevelopmentintheworld,themanagementofhumanbeh... 相似文献
995.
996.
湖泊水质富营养化评价的物元分析法 总被引:16,自引:2,他引:16
建立了利用物元分析理论进行湖泊水质富营养化评价的新模型.并研究了我国五个主要湖泊的富营养化状况,和其它方法比较,取得了满意的结果. 相似文献
997.
对偶线性规划模型在大气污染物最优化控制中的应用 总被引:3,自引:0,他引:3
针对大气污染的问题,运用系统工程的方法,建立对偶线性规划模型,采用最优控制理论对大气环境治理实施最优控制,最终实现经济效益,社会效益和环境效益的统一。 相似文献
998.
通过水稻盆栽实验和沈阳西部污水生态工程土地处理系统试验,应用回归分析等方法研究了合成洗涤剂LAS在土壤-水稻系统中的净化规律和沈阳西部污水生态工程土地处理系统不同生态结构类型的土壤-植物系统对LAS的净化效果。其结果是:(1)LAS在土壤-水稻系统中的净化速率符合一级反应动力学方程,其半衰期为2S—30天,净化率达93—94%;(2)在目前沈阳西部原污水中LAS含量情况下,土壤—植物系统可使LAS浓度降低一个数量级。 相似文献
999.
表面活性剂(LAS&NIS)的环境安全性评价 总被引:10,自引:0,他引:10
阴离子表面活性剂直链烷基苯磺酸盐(LAS)和非离子表面活性剂(NIS)是产量和消耗量都相当大的两类表面活性剂。文章从生物降解性、毒性及在环境和生物体内的累积性3个方面分析了它们的环境安全性,认为表面活性剂对环境会产生不同程度的影响。LAS对动植物有毒害,在环境中和生物体内有累积(尽管易降解),应引起重视;NIS中脂肪醇聚氧乙烯醚(APEO)的降解产物毒性高、降解速度慢,对环境有很大的危害。 相似文献
1000.
地表水环境质量灰关联评价方法探讨 总被引:6,自引:2,他引:6
针对当前灰关联评价法的不足 ,采用线性内插的方法进行了改进 ,提高了分辨率 ,在此基础上 ,以马颊河为例 ,对其 1 986~1 998年间的水环境监测数据进行了评价 ,得到了较为可靠且可比的结果。 相似文献