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911.
Environmental impact of two successive chemical treatments in a small shallow eutrophied lake: Part I. Case of aluminium sulphate 总被引:1,自引:0,他引:1
Van Hullebusch E Deluchat V Chazal PM Baudu M 《Environmental pollution (Barking, Essex : 1987)》2002,120(3):617-626
This paper deals with the efficiency and effects of addition of aluminium sulphate on soft water quality of a shallow eutrophic lake. Almost all the controlled variables improved with treatment, especially nutrient concentrations such as soluble reactive phosphorus (SRP) and transparency. However, aluminium sulphate was not added in sufficient quantity to reduce the total phosphorus content. SRP concentration was significantly reduced in the short term. Moreover, external loading of phosphorus was high and not taken into account by the in-lake treatments. Finally, resuspension of sediment (polymictic lake) removed the alum hydroxide layer on the sediment surface, which reduced treatment effectiveness. No significant pH decrease was noted following alum addition. According to bibliographical toxicological data, monomeric aluminium content does not show any toxic effect on aquatic fauna and flora. In spite of low SRP in the water column, the treatment did not prevent appearance of Microcystis sp. colony (> 10 colony per ml) approximately 30 days after alum application. 相似文献
912.
西安地区旅游景点水体卫生细菌学调查及保护对策 总被引:1,自引:0,他引:1
以粪大肠菌和异养细菌总数做指标,对西安地区旅游景点水体的卫生细菌学状况进行了调查。结果表明,西安市区内旅游景点的人工湖、天然湖等大都受到不同程度的污染,而离市区较远、海拔较高的旅游景点则污染较轻。 相似文献
913.
Mariusz O. Jedrysek 《Environmental Chemistry Letters》2005,3(3):100-112
Microbial oxidation of organic compounds (including methane), in freshwater sediments, may result in precipitation of carbonates,
which may become an important geochemical archive of paleoenvironmental variations. Most probably low δ13C value in calcite in eutrophic systems results from an advanced oxidation of organic compounds in turbulent or/and sulphate-rich
conditions. Likewise, high δ13C value in calcite from organic-rich sediments may evidence low redox potential of the freshwater system. Oxidation of methane
and organic matter results in significant isotope effects in sulphates dissolved in water. Therefore, to better understand
the origin of carbon isotope signal in carbonates, concentration and stable isotope measurements in dissolved sulphate (water
column), bubble methane and calcite (freshwater sediments) have been carried out in 24 lakes, 2 ponds and 4 rivers in Poland.
The highest concentration of sulphate has been detected in rivers (85.47 SO4
2− mg/l) and an artificial lake (70.30 SO4
2− mg/l) located in the extremely SO4
2−-polluted region called the “Black Triangle”. The lowest concentration of sulphate is found in dystrophic and mountain lakes
(from 0.5 SO4
2− to about 3 mg/l). The lowest δ34S(SO4
2−) and δ18O(SO4
2−) values occur in unpolluted lakes in eastern Poland (−0.94 and 1.38‰, respectively). The highest S and O isotopic ratios
are found in a polluted lake in western Poland (δ14S(SO4
2)=12.95‰) and in a dystrophic lake in eastern Poland (δ18O(SO4
2) = 16.15‰) respectively. It is proposed that δ34SO4
2− and (18O(SO4
2−) values in lakes represent a good tool to assess and quantify anthropogenic impact by acid precipitation and to monitor variations
in the trophic state and redox processes controlled by biodegradation of organic compounds in sediments and water column.
In general, increasing depth (up to 12 m) of the water column is associated with decreasing trend the δ13C(CH4) value from about –35 to about –78‰. However, δ13C value in sedimentary calcite (δ13C vary from –10 to 0.5‰) shows opposite trends as compared to the corresponding methane. This is probably due to redox processes
and distribution of heavy isotopes between methane and calcite. Likewise, turbulent water (river) show high δ13C value in methane and low δ13C value in calcite—this is probably due to an enhanced oxidation of methane producing 13C-depleted CO2. In contrast to clean lakes, it is observed that an increase of the δ13C(CH4) value occurs with increasing depth of the water column in a strongly SO4
2−-contaminated lake. This is probably due to a loss of biological buffering potential of the lake accompanied by an active
oxidation of methane precursors. 相似文献
914.
Modelling the responses of the Lagoon of Venice ecosystem to variations in physical forcings 总被引:1,自引:0,他引:1
A Finite Element Ecological Model for the Lagoon of Venice (VELFEEM) has been used to test the responses of the Lagoon of Venice ecosystem to variations in physical conditions.The model is obtained by coupling a finite element hydrodynamic model, that computes the velocity fields of water, an energetic model to compute the water temperature fields, and an ecological model that simulates the dynamic of phytoplankton, zooplankton, nutrients (ammonia, nitrate and phosphate) organic detritus (organic nitrogen, organic phosphorous and CBOD) and dissolved oxygen.The transport model is a two-dimensional barotropic finite element model which allows for a better resolution of the lagoon morphology.The ecological model has been developed by starting from the ecological module EUTRO of WASP (Water Analysis Simulation System released by US EPA), and by adapting it to the peculiarity of the Lagoon of Venice.A reference condition has been identified by running a 1-year simulation under climatologic condition. Then, the sensitivity to physical forcing (tide and wind) and to the input of macronutrients has been investigated, by comparing model predictions of spatial and temporal evolution of major state variables and of an aggregate index of Water Quality Trophic Index (TRIX). 相似文献
915.
华北地区城市地下水中主要离子含量升高机理分析——以洛阳市为例 总被引:4,自引:0,他引:4
本文以洛阳市为例,讨论了华北地区地下水中主要离子的背景浓度及其形成作用。在此基础上,重点阐述了地下水中Ca^2+,Mg^2+浓度升高的若干机理,并对污染源各不相同的三个水源地地下水Ca^2+,Mg^2+浓度升高机理进行了定量分析,比较了Ca^2+,Mg^2+浓度与其它主要离子浓度的相关特征,研究表明:该区两类地下水主要形成了钙长石和镁榄石的风化作用,地下水中CO2分压升高,可促进Ca,Mg硅酸盐, 相似文献
916.
基于监测样本信息的水环境系统权重分配方法 总被引:4,自引:0,他引:4
针对水环境系统权重分配问题,从建筑系统客观背景入手,以环境因子监测样本资料为信息源,通过构造关联信息矩阵,并采用旋转正交转变换的主成分分析法,定量地描述了交五因子在整体系统的贡献,最后依贡献量大小识别对应各个因子的权重值,实例表明,该方法物理意义清晰结果客观合理。 相似文献
917.
国内外水环境管理体制对比分析 总被引:8,自引:0,他引:8
水环境管理体制建设是一项复杂的系统工程;即使在发达国家,水环境管理模式也随着认识水平的提高与需求的不断变化,处于逐步完善的过程。本文收集了国际上在水环境管理方面比较有代表性的国家,包括美国、英国、法国、荷兰、加拿大、澳大利亚、前苏联、日本、韩国、以色列与印度等水环境管理体制方面的资料,系统分析了这些国家在国家级、流域级与区域级的水环境管理体制与主要采取的水环境管理模式;并针对我国水环境管理体制的结症所在,提出了我国水环境管理体制改革所需遵循的基本原则。 相似文献
918.
利用计算机图像处理和多元统计方法处理了无锡市卫星遥感数据,形象直观地显示了无锡市水环境的宏观面貌,较好地反映了无锡水网主干河道的水质空间分布特征。研究表明,卫星遥感技术作为地面监测方法的一种有效补充,可提供丰富的遥感水质信息。 相似文献
919.
920.