Spatial analysis of water quality trends in the Han River basin, South Korea

Spatial patterns of water quality trends for 118 sites in the Han River basin of South Korea were examined for eight parameters-temperature, pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended sediment (SS), total phosphorus (TP), and total nitrogen (TN). A non-parametric seasonal Mann-Kendall's test determined the significance of trends for each parameter for each site between 1993 and 2002. There are no significant trends in temperature, but TN concentrations increased for the majority of the monitoring stations. DO, BOD, COD, pH, SS, and TP show increasing or decreasing trends with approximately half of the stations exhibiting no trends. Urban land cover is positively associated with increases in water pollution and included as an important explanatory variable for the variations in all water quality parameters except pH. Topography and soil factors further explain the spatial variations in pH, COD, BOD, and SS. BOD, COD, SS, and TP variations are consistently better explained by 100m buffer scale analysis, but DO are better explained by the whole basin scale analysis. Local water quality management or geology could further explain some variations of water quality. Non-point-source pollution exhibits strong positive spatial autocorrelation as measured by Moran's I, indicating that the incorporation of spatial dimensions into water quality assessment enhances our understanding of spatial patterns of water quality. The spatial regression models, compared to ordinary least square (OLS) models, always better explain the variations in water quality. This study suggests that spatial analysis of watershed data at different scales should be a vital part of identifying the fundamental spatio-temporal distribution of water quality.     

主成分分析法在乐安河水质评价中的应用

采用主成分分析法,借助SPSS软件,对乐安河7个监测断面的DO、COD、CODMn、BOD5、NH3-N、Cu、Cr等7个水质指标进行了分析计算.从原始数据中提取占总方差的82.367%的两个因子来反映水体的污染程度,经分析识别得到了乐安河的两个主成分因子:有机物及重金属(Cu、Cr),结果与实际情况相吻合.证实主成分分析法是一种有效的水质评价方法.     

Moderating effects of the geometry of reservoirs on the relation between urban land use and water quality

Edges mediate the material flux between adjacent systems. This mediating effect of edges is strongly tied to the complexity of the adjacent shapes. Land use within a watershed has a direct impact on the water quality of adjacent aquatic systems. Hydrological processes carry material produced by land-use activities into aquatic ecosystems through the edges of the ecosystem. Therefore, the geometry of aquatic ecosystems theoretically affects the relationship between land use and water quality. This study investigates whether the shape complexity of reservoirs moderates the direct impact of land use on the water quality of adjacent reservoirs. A moderation model was adopted to measure the shape effects, and 153 reservoirs were randomly sampled with a consideration of reservoir size (surface area), geographic location, and data availability. With a focus on urban land use, we used GIS to measure land-use types within a 1 km buffer of reservoir boundaries. The shape complexity of sampled reservoirs was measured using fractal dimensions. Land uses and shape complexity were then regressed to measure water quality parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP). Correlation analysis revealed that the shapes of reservoirs are likely to be simple where urban land use dominates the areas close to reservoirs. Use of the standard regression model indicated that the increasing shape complexity of reservoirs significantly reduces the concentration of BOD, COD, and TP within reservoir water. Moderation models for BOD, COD, TN, and TP suggest that shape complexity can considerably relieve the negative impacts on water quality of urban land use in areas adjacent to reservoirs. The results of this study highlight the need to focus on shoreline management in order to mitigate the adverse impacts of land use on lakes and reservoirs.     

基于主成分分析的松花江流域黑龙江段水质评价

对松花江流域黑龙江控制区段13个监测断面不同水期的水质指标进行主成分分析,以鉴别主要的污染源,进而提出有针对性的水污染控制对策。结果表明,BOD5、COD、TP、TN为主要污染指标,合计贡献率为49. 529%,首要污染源为生活污水与农业废水。第二大污染指标主要为石油类、阴离子表面活性剂、氰化物,主要来源于工业废水。总污染最严重的主要是阿什河口内平水期与龙安桥平水期。龙安桥平水期等对应的河流区段受生活污水及农业废水污染较为严重,苗家平水期等对应的河流区段受工业污染较为严重。     

深圳龙华污水处理厂的工程设计与调试

龙华污水处理厂设计采用了A2/O/Aqua-ABF滤池/辅助化学除磷处理工艺,出水执行《城镇污水处理厂污染物排放标准》（GB 18918—2002）中的一级A标准。经过调试,出水实现了达标排放,在进水平均COD、BOD5、SS、TP、TN、NH3-N分别为259.1、118.3、369.9、5.7、32.0、23.2mg/L时,出水分别为14.8、4.9、4.7、0.7、11.2、4.0mg/L。     

改良A~2/O工艺在长春北郊污水厂的应用

改良A2/O污水厂工艺运行稳定,具有较强的抗冲击性能,出水水质优于设计标准。平均进水COD为433mg/L时,平均出水COD为58.8mg/L,平均COD去除率达到86.3%,平均BOD5去除率达到91.8%,平均NH3-N去除率达到88.5%,平均TP去除率达到81.1%,均达到国家GB18918-2002污水排放一级B标准。     

OAO工艺在镇江市新区大路污水厂的应用

镇江市新区大路污水厂采用好氧-厌氧-好氧(OAO)工艺。在进水COD、BOD、SS、NH3-N、TP浓度分别为263.00、106.00、118.00、17.00和3.25 mg/L的条件下,处理出水COD、BOD、SS、NH3-N、TP浓度分别为41.000、8.000、8.000、3.780和0.348 mg/L,出水达到GB 18918—2002《城镇污水处理厂污染物排放标准》的一级A标准。     

上海中心城区合流制排水系统雨天溢流水质研究

合流制排水系统雨天溢流已成为上海中心城区河道的主要污染源.为此,重点研究了上海中心城区某合流制排水区域JXB系统雨天污染物溢流的出流过程和污染物的事件平均浓度,并探讨了溢流污染物的初期效应.结果表明,降雨特性对污染物溢流过程的水质影响较大;该区域雨天溢流COD、BOD5、SS、NH3-N的事件平均浓度分别为268、101、110、9.5 mg/L,SS浓度明显低于相关研究的结果;分析溢流污染物的初期效应表明,JXB系统排江污染物的初期效应较为显著,其中COD和BOD5的初期效应比SS的显著.     

基于区域水量-水质的水资源承载力研究

目前国内外对水资源承载力的研究都存在较多关注水资源数量而忽略水质的问题,然而在水资源的实际利用中,最小生态需水量、水环境容量也是水资源承载能力的重要约束条件。基于此,对水资源承载力的概念提出新的理解,从水量和水质角度出发,建立了以最小生态需水量、水环境最大可容纳量为约束条件的水资源承载力模型,提出以人口和经济承载规模来表征水资源承载力。以北京市房山区为例,选取COD和NH₃-N为主要污染因子,通过一维稳态水质模型计算研究区域内河道纳污能力,进而推算出在水量-水质约束条件下的水资源可利用量对研究区域经济系统的支撑能力。结果表明:房山区不同水功能区由于其河段长度、现状水质不同,导致纳污能力差别较大;河流对COD和NH₃-N的纳污能力分别为4 411. 92 t/a和121. 61 t/a,预测2030年房山区水资源承载力即GDP规模为3 348. 43亿元、人口数量为243万人。     

Treatment of landfill leachate using an aerated, horizontal subsurface-flow constructed wetland

A pilot-scale subsurface-flow constructed wetland was installed at the Jones County Municipal Landfill, near Anamosa, Iowa, in August 1999 to demonstrate the use of constructed wetlands as a viable low-cost treatment option for leachate generated at small landfills. The system was equipped with a patented wetland aeration process to aid in removal of organic matter and ammonia nitrogen. The high iron content of the leachate caused the aeration system to cease 2 years into operation. Upon the installation of a pretreatment chamber for iron removal and a new aeration system, treatment efficiencies dramatically improved. Seasonal performance with and without aeration is reported for 5-day biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), ammonia nitrogen (NH(4)-N), and nitrate nitrogen (NO(3)-N). Since winter air temperatures in Iowa can be very cold, a layer of mulch insulation was installed on top of the wetland bed to keep the system from freezing. When the insulation layer was properly maintained (either through sufficient litterfall or replenishing the mulch layer), the wetland sustained air temperatures of as low as -26 degrees C without freezing problems.