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171.
IdentificationofbiomarkersofcoresfromtheSouthChinaSea¥TangYunqianandLiuKewen(ReceivedAM10,1994;acceptedJuly5,1994)(SecondInst... 相似文献
172.
Water pollution sources assessment by multivariate statistical methods in the Tahtali Basin,Turkey 总被引:3,自引:0,他引:3
In this study, multivariate statistical methods including factor, principal component and cluster analysis were applied to
surface water quality data sets obtained from the Tahtali River Basin, Turkey. Factor and principal components analysis results
revealed that surface water quality was mainly controlled by agricultural uses and domestic discharges. Cluster analysis generated
two clusters. Based on the locations of the sites consisted by each cluster and variable concentrations at these stations,
it was concluded that agricultural discharges strongly affected north and northeast part of the region. These methods are
believed to assist water managers to understand complex nature of water quality issues and determine priorities to improve
water quality. 相似文献
173.
通过对廊坊市近20年来浅层地下水水位观测资料进行整理分析,揭示了其水位动态曲线特征及其变化规律,找出了影响浅层地下水水位动态变化的主要因素,并就合理开发、科学利用浅层地下水资源提出了切实可行的对策措施。 相似文献
174.
In this study,a novel culture medium that simulates shrimp pond conditions was established to screen nitrite-degrading isolates.The medium was supplemented with nitrite as a nitrogen source and shrimp feed as the major carbon source,to achieve the high nitrogen and low carbon nutritional status found in shrimp farming ponds.Screening using this medium identified potent denitrifying Bacillus isolates,among which Bacillus subtilis M7-1 was considered best.M7-1 was able to completely degrade nitrite-N in 24 h without much consumption of dissolved oxygen.Efficient denitrification activity took place in liquid cultures within a set of non-stringent ranges of pH(5.0–9.0),salinity(0–30)and temperature(25–35℃).The denitrifying enzyme gene was amplified,sequenced and further identified as nirS type.In biosecurity assessments,M7-1 had no negative effects on shrimps at a dose of 106 cfu mL−1.M7-1 could therefore be used in aquaculture to reduce and control the nitrogen concentration,and to promote the development of sustainable and healthy culture systems. 相似文献
175.
176.
为了解研究区岩溶地下水水质形成及离子质量浓度空间变异影响因素,以毕节市大方县南部为研究区,采用因子分析方法对56组水样进行分析,得到基于研究区岩溶地下水水质形成及其影响的4组因子(F1、F2、F3、F4):F1以TH、TDS、COD、Ca2+、SO42-、F-为主,代表了碳酸盐岩及膏盐矿物的充分溶解对水质的影响;F2以游离CO2、Mg2+、HCO3-为主,反映了碳酸盐岩中白云石矿物的溶解对水质的影响;F3以Na+、K+、Cl-为主,代表了盐岩溶解、大气降水对水质的影响;F4以pH、NO3-为主,揭示了人类生活污水和农业灌溉污水对岩溶地下水水质的影响。以上4种因子可以解释研究区岩溶地下水水质影响因素的80%以上。 相似文献
177.
旅游业日益成为各国各地区重点扶持的战略产业,旅游环境竞争力的研究是旅游竞争力研究的重要方面。本文构建了旅游环境竞争力评价指标体系,借助SPSS17.0统计软件,运用因子分析法和聚类分析法,定量评价了西北五省区旅游环境竞争力,并依据评价结果提出了提升区域旅游环境竞争力和加强区域旅游合作的措施及建议。 相似文献
178.
《Chemie der Erde / Geochemistry》2014,74(4):641-651
Groundwaters in the crystalline aquifers are the major source of drinking water in Vaniyambadi area of Vellore district. Geochemical methods in collaboration with statistical methods were applied in this industrial area to understand the natural and anthropogenic influences on groundwater quality. To accomplish this objective, groundwater samples were collected and analyzed for physicochemical parameters and the results showed a dominance in the order of Na+ > Mg2+ > Ca2+ > K+ and HCO3− > Cl− > SO42− > NO3− for anions and cations, respectively. In contrast to this anion dominance were changed to Cl− > HCO3− > SO42− > NO3− in samples collected near the tannery industries. Groundwater quality evaluation using TDS and TH suggested that 57% of the total samples are hard-brackish type, indicating its unsuitability for drinking purpose. Generally the water type is Na+Cl− to Ca2+Mg2+HCO3− type with an intermediate Ca2+Mg2+Cl−, suggesting the mixing of fresh groundwater with tannery effluent and cation exchange. Factor analysis and bivariate plots of major ions suggests that both natural and anthropogenic inputs are equally influencing the groundwater quality. Further investigations proved that silicate weathering is the dominant geogenic source of groundwater solute content, whereas tannery effluent is the anthropogenic source. Saline water mixing index (SWMI) and Cl− vs NO3− bivariate plot were employed to differentiate the tannery contamination from the other anthropogenic inputs such as agricultural fertilizers, municipal sewages, etc. This analysis shows that samples 2, 4, 8 and 9 (located within the tannery cluster) have a SWMI value greater than 1, representing the groundwater–tannery effluent mixing. This study infers that groundwater in the Vaniyambadi area is under serious threat from both natural and anthropogenic contamination. However, the controlling discharge of untreated tannery effluents must be regulated to reduce the further deterioration of this vital resource in this part of the country. 相似文献
179.
In general, the determination of the factor of safety and the location of the critical slip surface are two major challenges in seismic slope stability analysis. In this paper, a new approach for determining the factor of safety and the corresponding critical slip surface of a layered rock slope subjected to seismic excitations is presented, through a case study based on the combination of the shear strength reduction technique and distinct element method. According to this proposed method, the seismic factor of safety and the critical slip surface of the slope are estimated and compared with those obtained by the pseudo-static approach, combined with the limit equilibrium method. It is found that the factor of safety obtained from the proposed method is slightly greater than that computed by the pseudo-static analysis, with a difference of 4.2%, and that the critical slip surface obtained from the two methods is identical, which confirms the reasonability and feasibility of the proposed method. 相似文献
180.