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861.
862.
海水中石油类国标分析方法存在的问题及改进建议 总被引:1,自引:0,他引:1
当前海水石油类分析三种国标方法存在代表性和适用性不足的问题,不同方法的数据间缺乏可比性,给政府和民众控制水体污染、评价水质状况带来偏差和不便。建议国家相关部门修订海水石油类分析方法,将水质石油类分析国标方法统一为红外分光光度法。通过海水样品加标实验验证了该方法的可行性,实际操作简便、准确。 相似文献
863.
Fanghua Hao Xuan Zhang Xiao Wang Wei Ouyang 《Journal of the American Water Resources Association》2012,48(6):1162-1177
Abstract: The constrained ordination method from quantitative ecology was utilized to assess the relationship between landscape patterns and nonpoint‐source (NPS) pollution for the purpose of identifying effective water‐quality improvement practices in Danjiangkou Reservoir (DJKR) basin, China. The soil and water assessment tool (SWAT) was applied to simulate NPS pollution and the Fragstats model was applied to calculate the landscape metrics. The study concluded that organic nutrients formed the main NPS pollutant in the DJKR basin and that most of the NPS pollution occurred along with soil loss. Based on partial redundancy analysis, the conclusion that landscape metrics were significantly correlated to NPS pollution indices was obtained. Specifically, the composition of LULC (land use/land cover) was the most effective factor to estimate NPS pollution. Dry cultivated land was identified as the main source of NPS pollution, and paddy fields were characterized with the most intensive soluble nutrients loss. In addition, the reason that fragmented and complex landscape patterns exacerbate NPS pollution was that natural landscape composed most of this area. Moreover, the fragmented natural landscape indicated intensive agricultural activities that were the crucial trigger for NPS pollution. Combined with the economic condition in China, Conversion of Cropland to Forests Program (CCFP) should be conducted selectively and gradually in the DJKR basin. 相似文献
864.
Biotransformation is widely recognized as the most important and most uncertain determinant of bioaccumulation. A step-wise method for estimating organism-specific biotransformation half-lives from field observations and using established food web modeling is developed. As a proof of concept, the method is applied to the case of nine polycyclic aromatic hydrocarbons (PAHs) in a well-studied food web in Bohai Bay, China. The estimated half-lives are in good agreement with the existing literature. The proposed biotransformation estimation method, through data mining, for sufficiently defined ecosystems, may greatly reduce the necessary animal testing involved in chemical assessments by providing useful guidance to experimentalists and regulators. 相似文献
865.
Proctor DM Suh M Aylward LL Kirman CR Harris MA Thompson CM Gürleyük H Gerads R Haws LC Hays SM 《Chemosphere》2012,89(5):487-493
Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in the stomach prior to absorption is a well-recognized detoxification process thought to limit the toxicity of ingested Cr(VI). However, administration of high concentrations of Cr(VI) in drinking water cause mouse small intestinal tumors, and quantitative measures of Cr(VI) reduction rate and capacity for rodent stomach contents are needed for interspecies extrapolation using physiologically-based toxicokinetic (PBTK) models. Ex vivo studies using stomach contents of rats and mice were conducted to quantify Cr(VI) reduction rate and capacity for loading rates (1-400 mg Cr(VI) L−1 stomach contents) in the range of recent bioassays. Cr(VI) reduction was measured with speciated isotope dilution mass spectrometry to quantify dynamic Cr(VI) and Cr(III) concentrations in stomach contents at select time points over 1 h. Cr(VI) reduction followed mixed second-order kinetics, dependent upon concentrations of both Cr(VI) and the native reducing agents. Approximately 16 mg Cr(VI)-equivalents of reducing capacity per L of fed stomach contents (containing gastric secretions, saliva, water and food) was found for both species. The second-order rate constants were 0.2 and 0.3 L mg−1 h−1 for mice and rats, respectively. These findings support that, at the doses that caused cancer in the mouse small intestine (?20 mg Cr(VI) L−1 in drinking water), the reducing capacity of stomach contents was likely exceeded. Thus, for extrapolation of target tissue dose in risk assessment, PBTK models are necessary to account for competing kinetic rates including second order capacity-limited reduction of Cr(VI) to Cr(III). 相似文献
866.
867.
介绍了固定污染源中挥发性有机物(VOCs)的主要采样方法,并重点介绍了动态稀释法在固定污染源中采样的应用。采用动态稀释法取样,对某汽车企业涂装车间的排放废气进行了定性分析,并对其中主要的10种VOCs进行了定量分析。研究了方法测定的稳定性,10种化合物相对标准偏差为9%~32%,符合工况变动范围。将不同采样时间及不同吸附材料的测定结果与在线监控数据进行比较,结果显示动态稀释法的测定结果均在实际工况波动范围内,说明该方法能够较好地满足汽车涂装行业VOCs的采样要求。 相似文献
868.
VOCs快速检测在某化工企业搬迁遗留污染场地调查中的应用 总被引:1,自引:0,他引:1
以天津市某化工企业搬迁遗留污染场地为例,采用VOCs快速检测法辅助现场钻孔取样,以初步判断土壤污染深度,同时将现场样品送实验室检测。试验表明,VOCs快速检测法与实验室检测法结果基本一致。将452个样品测定结果做比对,结果表明实验室检测数据VOCs加和值与快速检测法现场检测数据存在显著相关,R2为0.803 7。污染物主要集中于场地5 m~9 m的粉土层中。其中,13种VOCs检出,4种VOCs超过《场地土壤环境风险评价筛选值》(DB11/T 811—2011)商业用地筛选值。 相似文献
869.
In the last decades the European Union exerted influence on precautionary environmental planning by the establishment of several Directives. The most relevant were the Habitat-Directive, the EIA-Directive, the SEA-Directive and the Water Framework Directive. Comparing these EU policies in the area of environmental precaution it becomes obvious that there is a lot of common ground. Thus, the conclusion seems likely that the European Union, in doing so, has intended to establish general planning concepts through introducing several methodological steps indicated by the regulations. The goal of this article is firstly to point out, which are the common planning principles, converted by methodological elements and secondly examine the consideration of these planning concepts by the implementation and application in the member states. In this context it is analysed whether the connections and divergences between the directives lead to significant differences in the implementation process. To this aim the directives are shortly introduced and significant steps of the processes regulated by them are outlined. In the second steps the national legal implementation in the Alpine states and its consequences for the practical application are discussed. The results show a heterogeneous application of the EU principles. Within the comparative view on the four directives influence and causalities between the national implementation and the practical application were identified, which can be simplified as four types. Since a coherent strategic and methodological concept for improving environmental precaution planning from part of the EU is noticeable, more unity and comparability within the implementation is desirable, particularly in areas with comparable habitats such as the alpine space. Beyond this the trade-off between the directives poses an important task for the future. 相似文献
870.
We consider the management of urban stormwater in two connected dams. Stormwater generated by local rainfall flows into a
capture dam and is subsequently pumped into a similar sized holding dam. We assume random gross inflow and constant demand.
If we wish to minimise overflow from the system then the optimal management policy is to pump as much water as possible each
day from the capture dam to the holding dam without allowing the holding dam to overflow. We shall refer to this policy as
the pump-to-fill policy. The model is based on the Parafield stormwater management system in the City of Salisbury (CoS) but assumes constant
demand instead of level dependent outflow. If there is insufficient water in the holding dam to meet the desired daily demand
then all water in the holding dam is used and the shortfall is obtained from other sources. CoS, in suburban Adelaide in South
Australia, is recognised in local government circles as a world leader in urban stormwater management. The water is supplied
to local industry to replace regular mains water and is also used to restore and maintain urban wetlands. In mathematical
terms the pump-to-fill policy defines a Markov chain with a large transition matrix and a characteristic regular block structure.
We use specialised Matrix Analytic Methods to decompose the event space and find simplified equations for the steady state
probability vector. In this way we enable an elementary solution procedure which we illustrate by solving the modified Parafield
problem. The optimal nature of the pump-to-fill policy is established in a recent paper by Pearce et al. (JIMO 3(2):313–320,
2007). The purpose of the current study is to find optimal management policies for urban stormwater systems.
Work supported by the Australian Research Council. 相似文献