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排序方式: 共有102条查询结果,搜索用时 265 毫秒
91.
ABSTRACT: Agricultural practices such as cattle grazing and animal manure application can contribute to relatively high runoff concentrations of fecal coliform (FC) and fecal streptococcus (FS). Available information, however, is inconsistent with respect to the effects of such practices as well as to measures that can discriminate among candidate sources of FC and FS. The objective of this study was to assess the effects of grazing, time of year, and runoff amounts on FC and FS concentrations and to evaluate whether FCIFS concentration ratios are consistent with earlier values reported as characteristic of animal sources. Runoff from four Northwest Arkansas fields was sampled and analyzed for fecal coliform (FC) and fecal streptococcus (FS) for nearly three years (1991–1994). Each field was grazed and fertilized, with two fields receiving inorganic fertilizer and two receiving animal manure. Runoff amount had no effect on runoff concentrations of FC or FS. There were no consistent relationships between the presence of cattle and FC and FS runoff concentrations. Both FC and FS concentrations were affected by the season during which the runoff occurred. Higher concentrations were observed during warmer months. Runoff FC concentrations exceeded the primary contact standard of 200 cfu/100 mL during at least 89 percent of all runoff events and the secondary contact standard of 1000 cfu/100 mL during at least 70 percent of the events. Ratios of FC to FS concentrations varied widely (from near zero to more than 100), confirming earlier findings that FC/FS ratios are not a reliable indicator of the source of FC and FS.  相似文献   
92.
With its total drainage basin of 37 107 km2 and mean annual discharge of 307 m3 s-1, the River Kymi is one of the largest in Finland. Presently it receives treated domestic wastewaters of about 160 000 inhabitants through eight treatment plants and treated industrial effluents from four paper mills, two cardboard mills and one pulp mill. In the 1960s all the wastewaters were discharged untreated to the river. However, the construction of domestic wastewater treatment plants began in the 1970s and mechanical wastewater treatment became common in industry. By the end of the 1980s practically all the wastewaters discharged to the river were treated in activated sludge processes. The aim of this paper was to investigate the influence of wastewater purification on the bacteriological quality of the river during these three decades. The bacteriological quality of the river was evaluated on the basis of annual medians of fecal streptococci (FS) calculated for 15 sites on the basis of 4804 FS enumerations from the years 1964-1992. The results show that the bacteriological quality improved steadily as the number of treatment plants increased and wastewater treatment became more effective. In the beginning of the 1960s the annual FS medians in the central part of the river were typically 1000-1500 CFU/100 ml, whereas in the 1990s they had decreased to 30-40 CFU/100 ml (CFU = colony forming units). The results indicate that FS input to the river was mainly of domestic origin.  相似文献   
93.
ABSTRACT: Driven by increasing concerns about bacterial pollution from agricultural sources, states such as Virginia have initiated cost sharing programs that encourage the use of animal waste best management practices (BMPs) to control this pollution. Although a few studies have shown that waste management BMPs are effective at the field scale, their effectiveness at the watershed scale and over the long term is unknown. The focus of this research was to evaluate the effectiveness of BMPs in reducing bacterial pollution at the watershed scale and over the long term. To accomplish this goal, a 1,163 ha watershed located in the Piedmont region of Virginia was monitored over a ten‐year period. Fecal coliforms (FC) and fecal streptococci (FS) were measured as indicators of bacterial pollution. A pre‐BMP versus post‐BMP design was adopted. Major BMPs implemented were manure storage facilities, stream fencing, water troughs, and nutrient management. Seasonal Kendall trend analysis revealed a significant decreasing trend during the post‐BMP period for FC concentrations at the watershed outlet, but not at the subwatershed level. Implementation of BMPs also resulted in a significant reduction in the geometric mean of FS concentrations. FC concentrations in streamflow at the watershed outlet exceeded the Virginia primary standard 86 and 74 percent of the time during pre‐BMP and post‐BMP periods, respectively. Corresponding exceedances for the secondary standard were 50 and 41 percent. Violations decreased only slightly during the post‐BMP period. The findings of this study suggest that although BMP implementation can be expected to accomplish some improvement in water quality, BMP implementation alone may not ensure compliance with current water quality standards.  相似文献   
94.
IntroductionLandtreatmentsystemfortreatingmunicipalsewagehasbeenfairlydevelopedathomeandabroad ,whichisalowcostandhighefficiencysewagetreatmentmethodoncertainconditions.InthepastafewyearsartificialaquaticproductsbreedingindustryhadrapiddevelopedinChin…  相似文献   
95.
Abstract:  Identifying the factors that influence the extinction risk of animals is essential in conservation biology because they help identify endangered species and provide the basis for their preservation. We present a comparative study that uses data from the literature on the diet and morphological specialization of European and North American bat species to investigate the effect of specialization on extinction risk. We focused on bats because many species are endangered and their high ecological diversity makes them a good model system for our purpose. After correcting for phylogenetic inertia, we compared the influence of dietary niche breadth as a measure of food specialization and of wing morphology as a measure of foraging strategy, habitat adaptation, and migratory ability on the vulnerability of 35 insectivorous bat species. Our results do not support the hypothesis that a narrow dietary niche breadth is related to high extinction risk. Instead they suggest that habitat specialization, which is reflected in wing morphology, influences the extinction risk of bats. Our study shows that an initial risk assessment in temperate-zone bats could be based on data of wing morphology but not on dietary data obtained from fecal analyses.  相似文献   
96.
97.
谢嵘 《干旱环境监测》2004,18(3):191-192
通过实验摸索出粪大肠菌群的一种五管发酵法。该方法检测下限为9个/L,适用于地表水和废水中粪大肠菌群的测定。  相似文献   
98.
通过响应面Box-Behnken实验设计,对镁盐回收高速铁路列车(高铁)粪便污水中磷进行优化研究,并对回收的产物进行分析.考察了p H值(8~10)、镁磷元素物质的量比(2~6)、反应时间(5~25 min)和温度(5~25℃)等条件对磷回收率的影响.结果表明,镁盐回收高铁粪便污水中磷的最优参数为:p H为9.5,镁磷元素物质的量比为5.7、反应时间为6.4 min、温度为5.0℃,磷的回收率响应值可达到95.3%.傅里叶变换红外光谱(FT-IR)和扫描电子显微镜(SEM)分析回收产物,表明主要的物质为磷酸铵镁,可能存在一定磷酸镁.能量弥散X射线(EDAX)分析回收产物,得到物质中磷元素的质量分数为17.1%.研究结果表明,运用镁盐从高铁粪便污水回收磷是可行的,具有一定的参考和借鉴意义.  相似文献   
99.
岩溶地下水的微生物污染日益严重,其来源的研究得到国际学术界的广泛关注.本研究以重庆南山老龙洞岩溶地下河系统为对象,采用滤膜法监测地下水中的总细菌、大肠杆菌、粪大肠菌及粪链球菌等微生物指标,以拟杆菌(Bacteriodes)为指示细菌,采用PCR-DGGE示踪地下水中大肠杆菌/粪大肠杆菌的来源.结果表明,老龙洞地下河流域各类细菌含量严重超标,总细菌数为10~2.9×10~7CFU·m L~(-1),大肠菌群总数达4.3~4.0×10~5CFU·m L~(-1),其中粪大肠菌群(FC)和粪链球菌(FS)分别最高达到1.1×10~6CFU·(100 m L)~(-1)、1.1×10~5CFU·(100 m L)~(-1);FC/FS多数为2以上,暗示流域地下水受人类粪便影响为主.地下水样和粪便样品的拟杆菌群落的PCR-DGGE比对分析表明地下水与人粪之间相似性为7.1%~69.1%,其中地下河出口处达到69.1%.地下水与猪粪之间相似性为1.1%~53.4%,地下河出口处仅为1.5%.因此,人类粪便为地下河污染的主要来源,猪粪污染为动物粪便污染的一部分,还存在其他动物粪便污染来源.此外,PCR-DGGE产物切胶测序发现大部分Bacteroides为人类肠道或粪便来源的细菌.  相似文献   
100.
用糖皮质激素受体重组基因酵母报道系统对3种天然与4种合成的糖皮质激素的糖皮质激素受体(GR)效应进行测定.结果表明,天然糖皮质激素中,肾上腺酮的活性最高;而合成激素中甲基强的松的活性最强.这些物质的GR效应与物质的化学结构密切相关.天然和合成糖皮质激素的GR效应随各自的辛醇水分配系数的增加而增强.  相似文献   
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