基于相关系数优化法的河流突发污染源项识别

基于相关系数优化法,结合地表水环境特征和污染物水质过程特征,推导出一维河道中单点源瞬时排放的源项反演算法,得到了污染源排放特征与河流环境特征参数的反演公式.采用假想算例进行数值试验,综合分析了流速信息、污染物衰减、监测距离、监测数据误差及中间参数?T选取等因素对反演结果的影响,确定了该方法的适用条件和最优条件的寻找方式.间隔10min进行两次监测采样,若监测误差小于5%,反演结果的相关系数达到-0.97,污染源位置和排放量反演结果的相对误差均小于4%,综合相对误差在2%以内.并且方法具有监测布点简单高效,数据需求低,编程简单等优点,值得在环境应急管理中进行实际应用.     

河网城市不透水面的河流生态系统响应:方法论框架

河网城市不透水面快速扩展,已成为影响河流生态系统健康的主要因素,理解掌握区域不透水面与河流生态系统之间的压力响应关系十分必要。以国外研究为重点,从不透水面的识别技术方法、 流域不透水面与河流生态系统状况之间的压力响应关系、 不透水面在流域土地利用规划调控和河流管理应用等三个方面,回顾了不透水面研究的主要进展,特别对不透水面影响河流生态系统的阈值效应进行了较细致梳理。从研究区域、 研究视角、 研究方法、 决策应用等四个方面,讨论了当前研究可能存在的问题。结合河网地区较为特殊的水文地貌特点,提出了河网城市开展相关研究的主要任务,认为必须解决的若干关键技术方法问题包括:不透水面实地调查方法及与有效不透水面转换、 汇水单元及其多尺度体系、 压力响应体系构建,以及数据分析技术方法等。最后以上海地区为案例,分析了河岸带尺度上的不透水面与河流生态系统之间的压力响应关系。这一研究体系框架试图为相关实证研究提供可实际操作的方法论参考。     

基于空间数据的太子河河流生境分类

在文献调研的基础上,结合河流特征和专家经验确定分类使用的指标,利用DEM、河流水系等空间数据,在ArcGIS软件下提取子流域,并计算子流域内河流系统的坡降、蜿蜒度、河网密度和河流等级4个分类指标值,应用聚类分析方法对太子河河流生境进行分类,将太子河河流生境分为源头陡峭河流生境、源头弯曲河流生境、源头河流生境、支流中下游河流生境、平原支流密集河网生境、支流弯曲河流生境、干流下游生境和干流蜿蜒河流生境等8种类型,各类型河流长度在223.8~773.1km之间,其中支流弯曲河流生境最长,而干流下游生境最短. 根据各生境类型的特征,提出了我国东北地区河流生境分类的指标参考值;根据不同生境类型的河道侵蚀、水量以及多样性潜力等特征,提出了不同河流生境类型的环境管理对策.      

Impact of drought on the ecological and chemical status of surface water and on the content of arsenic and fluoride pollutants of groundwater in the province of Salamanca (Western Spain)

The impact of drought on the ecological and chemical status of surface and groundwaters of the River Tormes (River Duero basin, northwestern Iberian Peninsula) was studied to evaluate the evolution of the quality of the river during its passage through the city of Salamanca (Spain). The Water Quality Index (WQI) of the river revealed that the drought period of 2005 did not significantly affect water chemical quality. However, during the study period differences were found in surface water ecological quality, using phytoplankton quality as AN indicator. These differences may be accentuated as a result of regulation of the River Tormes by the Santa Teresa reservoir. Arsenic and fluoride concentrations were measured in water wells, finding higher arsenic concentrations after the drought period and no correlation between the arsenic and fluoride contents. The results are useful for an overall understanding of potential impact of climate change on the ecological and chemical status of water in regional systems.     

The Distribution and Impacts of Dioxins and Polychlorinated Biphenyls in the Taiwan Er-Jen River

Abstract

The distribution and impacts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and polychlorinated biphenyls (PCBs) in the Taiwan Er-Jen River were investigated by monitoring fish distribution and measuring PCDD/DFs and PCBs levels in sediment and fish samples. Most of the fish collected are pollution-resistant species such as Oreochromis spp, Liza macrolepsis, Channa spp and Megalops cyprinoides. the most polluted river sections are in the upstream where large amount of waste effluents from households, livestock rearing and nearby dumping sites were discharged into the river, and the lower reaches of the river where metal recovery activities including open burning of waste electrical wire/scrap occurred. Sediment samples collected near the burning site show 2,3,7,8-TCDD toxicity equivalents (TEQ) ranging from 0.014 to 14.2 ng g^?1 by PCDD/DFs and from 0.015 to 1.03 ng g^?1 by coplanar PCBs (Co-PCBs). the fish samples show TEQ ranging from 0.029 to 0.615 ng g^?1 by PCDD/DFs and from 0.012 to 0.12 ng g^?1 by Co-PCBs. Possible PCDD/DFs sources are discharged PCBs, open burning of waste wire/scrap, and pentachlorophenol. the consumption of these fish will cause an average intake of 54 pg kg^?1 d^?1 TEQ. the prevention of direct discharge of livestock and the dumping of waste effuents into River Er-Jen as well as the control of metal recovery activities appears to be the first step toward the restoration of River Er-Jen.     

Spatial distribution of perfluorooctane sulfonate (PFOS) in major rivers in southwest Nigeria

Concentrations of perfluorooctane sulfonate (PFOS) were measured for the first time in major rivers within southwest, Nigeria. PFOS was concentrated from water and sediment using solid-phase extraction, identified and quantified with high-performance liquid chromatography coupled with tandem mass spectrometry. Concentrations of PFOS ranged from 1.71 to 16.19 ng L^?1 in water, and from 1.64 to 10.29 ng g^?1 in sediments across all locations. Comparatively, the concentrations of PFOS observed in this study were within the range ever measured in the environment. Field-based sediment water distribution coefficients (log K_d, L kg^?1) ranged from 2.08 to 3.56. While no correlation was observed between K_d and organic carbon contents, there was significant positive correlation between K_d and salinity (r² = 0.7867), which suggested that activities capable of increasing salinity can enhance PFOS removal from the environment.     

A sensitive method for selective determination of vanadium species by dispersive liquid–liquid microextraction (DLLME) with spectrophotometric detection

A simple, fast, and low-cost analytical procedure was developed for trace-level determination of inorganic vanadium species by dispersive liquid–liquid microextraction in combination with spectrophotometry. Vanadium in pentavalent form, V(V), was quantitatively extracted into organic phase as 4-(2-pyridylazo)-recorcinol (PAR) complex in the presence of N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) as counter-ion. Vanadium (IV) was masked with 1,2-diaminocyclohexanetetraacetic acid to allow speciation analysis. Total vanadium was determined after oxidation of V(IV) to V(V). The main factors affecting preconcentration and spectrophotometric detection of vanadium species such as pH, concentration of PAR and CTAB, the type and volume of the extraction, and disperser solvents were optimized. The limit of detection and enhancement factor obtained under optimum conditions were found to be 0.06 μg L^?1 and 98, respectively. Relative standard deviations for V(IV) and V(V) at 3.0 μg L^?1 were less than 2.4%. The presented procedure was applied to environmental water samples for selective determination of vanadium species. Moreover, the method was applied to determination of vanadium in edible salt samples, due to its applicability in high-NaCl-containing solutions. The validity of proposed method was proven by spike recovery experiments and also independent analysis by inductively coupled plasma mass spectrometry.     

Determination of pesticide residues in muscle of Cyprinus carpio from River Ravi

The levels of dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), endosulfan, endosulfan sulfate, carbofuran, and cartap were determined in muscles of Cyprinus Carpio sampled from 10 different sites of River Ravi between Shahdara to Balloki Headworks to assess level of contamination of these pesticides by GC-ECD (gas chromatograph equipped with electron capture detector) method. All fish samples were found contaminated with different concentrations of DDT, DDE, endosulfan, and carbofuran. DDT and DDE concentrations were higher than maximum residue limits (MRL) in food standards, while endosulfan sulfate and cartap were not detected. These findings indicate that pesticide concentrations in fish muscles decreased in the order: DDT > DDE > carbofuran > endosulfan. Furthermore, the sampling sites after Degh fall and beyond Hudiara Nulla Fall river sampling sites were more polluted. It is proposed that constant monitoring programs are needed to assess potential exposure risks.     

上海市河网水体中As的分布特征及其生态风险评价

2012年4月,在上海市河网采集表层水和沉积物样品各53个,测定其As含量,并采用潜在生态风险指数法对沉积物As的污染状况进行了评价。研究结果表明,上海市河网表层水和沉积物中As的含量分别为0.47～8.84μg·L-1和3.72～12.65μg·g-1,其中表层水中As的浓度处于中国地表水环境质量标准Ⅰ类水平,沉积物中As的浓度有15个样点超过了上海市土壤背景值,但均低于欧盟标准推荐值;表层水中As的浓度与pH呈显著正相关,说明pH值影响河水中As的迁移和转化;沉积物中As的浓度与总有机碳含量呈显著性正相关,说明沉积物中的As主要与总有机碳结合在一起;潜在生态风险评价结果显示,上海市河网沉积物中的As属于低生态风险。     

污染场地河道底泥浸出液对斑马鱼胚胎的毒性效应

为了评价某污染场地河道底泥对水生生物的毒性效应及其潜在生态风险,以斑马鱼(Brachydanio rerio)为受试生物,进行了河道底泥浸出液对斑马鱼胚胎的发育毒性实验。结果表明,5种底泥浸出液(A1、A2、A3、A4、A5)对斑马鱼胚胎的发育均有毒性效应,浸出液对斑马鱼胚胎的死亡率存在一定的剂量-效应关系,随着浸出液体积分数的增加,死亡率显著上升。浸出液对胚胎孵化抑制作用明显,随着浸出液体积分数的增加,孵化率显著下降。且能引起斑马鱼胚胎多种中毒症状,如水肿,鱼体弯曲,发育不全等异常现象,表明该段河道底泥存在潜在的生态风险。因此,在后期的污染场地河道整治中,需对河道底泥进行挖掘清理和无害化处理。