Distribution and source of microplastics in China's second largest reservoir - Danjiangkou Reservoir

Fresh water microplastic pollution is of pressing concern globally, but its distribution and sources in reservoirs are poorly documented. Danjiangkou Reservoir is the second largest reservoir in China and is divided into the Han Reservoir and Dan Reservoir. In this work, microplastic abundances and morphological characteristics of the reservoir were investigated. The microplastic abundance of 15 main tributaries of the reservoir was also measured. The vertical distribution (in water column and sediment), horizontal distribution (in Han Reservoir and Dan Reservoir) and source of microplastics were analyzed. Microplastics accumulated in the middle layer of the reservoir, and the size and color of the microplastic particles changed from the surface to the bottom, which implies that surveys of surface water are not enough to determine the microplastic contamination for deep water reservoirs. In the surface water, the microplastic abundance in the Han Reservoir was lower than that in the Dan Reservoir (p < 0.05), but microplastic abundance did not differ significantly in the intermediate and bottom water. Tributaries were one of the main sources of microplastics for Han Reservoir but not for Dan Reservoir. Agricultural cultivation in the hydro-fluctuation belt might be an important source of microplastics in the Dan Reservoir, which should be given additional attention. The results of this study can provide valuable information for developing microplastic sampling strategies in deep water reservoirs. Further studies are recommended to investigate the process through which microplastics in the hydro-fluctuation belt enter the reservoir and the sinking behavior of microplastics in the reservoir.     

三峡库区蓄水运用期表层沉积物重金属污染及其潜在生态风险评价

为全面了解蓄水运用期三峡库区表层沉积物中重金属含量及其潜在生态危害程度,在三峡库区干流及支流共采集了24个沉积物样品,测定了Cu、Pb、Zn、Cd、Ni、Cr、As和Hg的含量,并采用地积累指数法和潜在生态风险指数法对沉积物中的重金属污染进行了评价.结果表明,三峡库区重金属元素Cu、Pb、Zn、Cd、Ni、Cr、As和Hg的平均含量分别为:76.03、59.40、137.63、0.75、46.81、86.31、18.07和0.109 mg.kg-1,均高于长江沉积物背景值.地积累指数法评价结果显示:重金属元素污染程度顺序为:Cd>Pb>Cu>As>Zn>Ni>Hg>Cr.潜在生态风险指数法评价结果表明,各重金属污染对三峡库区构成的潜在生态危害由强至弱依次为:Cd>Hg>Cu>As>Pb>Cr>Zn,其中Cd的贡献因子最大.总体上讲,三峡库区蓄水运用期处于轻微生态危害等级,并未受到明显的重金属污染.     

福州山仔水库水华微囊藻毒素时空分布特征

在福州市第二饮用水源地山仔水库选取七里(库区入口)、库心(库区中心)和坝前(库区出口)3个典型断面,研究了2008年7～12月蓝藻水华发生至消退后期水体中溶解性微囊藻毒素(Extracellular Microcystins,EMCs)和藻细胞内微囊藻毒素(Intracellular Microcystins,IMCs...     

基于MIKE 21的汾河水库挟沙水流水质数值模拟研究

为了揭示悬浮泥沙(SSC)对水库水质的影响规律,对汾河水库进行样品收集和长期水质监测,采用水动力模型与泥沙转移和富营养化模型相结合的方法,将这三者关联耦合,并通过实测数据对模型进行参数率定和验证,分析含沙水和不含沙水中总氮(TN)、总磷(TP)、叶绿素a(Chla)、溶解氧(DO)四项指标,得出两者对水质造成的影响。结果表明:SSC对TN、TP的去除作用明显,对Chla、DO浓度分布影响较小,并计算了污染物的释放量以及贡献率,得出TP的负荷仅为16.47t,而贡献率高达25.25%。因此在汾河的污染控制方面应侧重削减磷,进而改善汾河地区的污染现状。     

三峡库区(重庆段)生态系统健康评价

生态系统的健康和相对稳定是人类赖以生存与发展的必要条件. 分析了三峡库区(重庆段)生态系统的健康状况,使用3S技术获取基础地理数据,构建基于压力-状态-响应模式的三级指标体系模型,并以AHP法结合专家咨询法选取人口密度、地质灾害易发度等10项指标,进行综合得分计算并分级. 结果表明:①在生态环境调查的基础上,应用GIS空间分析方法进行生态系统健康评价具有可操作性和结果的可靠性;②三峡库区(重庆段)生态系统健康质量表现出2～4级生态系统占主体(82.6%)的特点,生态质量一般,人类社会经济活动对生态系统的健康状况造成较大影响;③生态系统健康质量水平分布表现出明显的区域差异,从行政范围来看,彭水县、巫山县较好,巫溪县、武隆县等次之,云阳市、万州区等则较差. 结合系统聚类分析方法分析三峡库区(重庆段)生态系统健康状况空间分异的成因;并从宏观尺度上提出了对该地区人为活动的不良生态后果予以积极预防和有效调控的综合对策.      

三峡库区太阳能资源基本特征及其演变

利用1961-2007年的日照时数建模计算了三峡库区的太阳辐射,在此基础上对库区的太阳能资源作了全面分析和评价。结果表明：库区年总辐射量介于3200～4400MJ/m²,与德国等太阳能利用大国相当;“下游多,上游少”是资源空间分布的基本特征,且在秋、冬季差异更为明显;资源的年变化具有“夏大冬小”的特点,同时呈典型“双峰结构”,最大和次大峰值分别出现在8月和5月;库区上游太阳能季节差异大,而中、下游四季差异相对较小;库区太阳辐射以散射辐射为主（平均为64%）,上游尤其明显;1961-2007年,资源量与直射比均呈明显下降趋势,且在夏、冬季下降尤为显著,分析表明这与轻雾日数和霾日数的增加有关;自20世纪90年代初起,资源量开始回升,有利于库区太阳能的开发利用。     

黑龙滩水库水质分布规律研究

通过黑龙滩水库中7个采样点,17个月21个指标的连续采样分析,数据显示出水库中水质理化指标,在水平分布上无大的差异。垂直分布上DO和CODMn变化较大,其浓度是随浓度而降低。其余指标在一年的周期内维持在稳定的水平上。除T－P外,水库中其余指标物在Ⅱ级标准内。T－P超标有富营养化的潜在危险。     

Experimental and numerical analysis of flow instabilities in rectangular shallow basins

Free surface flows in several shallow rectangular basins have been analyzed experimentally, numerically and theoretically. Different geometries, characterized by different widths and lengths, are considered as well as different hydraulic conditions. First, the results of a series of experimental tests are briefly depicted. They reveal that, under clearly identified hydraulic and geometrical conditions, the flow pattern is found to become non-symmetric, in spite of the symmetrical inflow conditions, outflow conditions and geometry of the basin. This non-symmetric motion results from the growth of small disturbances actually present in the experimental initial and boundary conditions. Second, numerical simulations are conducted based on a depth-averaged approach and a finite volume scheme. The simulation results reproduce the global pattern of the flow observed experimentally and succeed in predicting the stability or instability of a symmetric flow pattern for all tested configurations. Finally, an analytical study provides mathematical insights into the conditions under which the symmetric flow pattern becomes unstable and clarifies the governing physical processes.     

北京官厅水库中有机氯类农药的分布和来源

采用气相色谱/电子捕获检测器法(GC/ECD)对官厅水库表层水体中18种有机氯农药进行分析.结果表明:官厅水库9个采样点水样中18种有机氯农药残留水平为10.06～87.37 ng·L-1,其中∑HCHs和∑DDTs分别为3.93～38.94和3.71～16.03 ng·L-1.官厅水库及其支流水体受到有机氯农药轻度污染,上游工业区废水排放以及各支流周边地区农田排水是官厅水库中有机氯农药的重要来源.与国内外其他地区相比较,官厅水库表层水体中有机氯农药含量较低,∑DDTs、γ-HCH和七氯环氧均未超过GB 3838-2002地表水环境质量标准限值.     

汾河水库水源河着生硅藻群落的DCCA研究

对汾河水库3条主要水源河的11个样点95个着生硅藻进行DCCA排序,这11个样点可分为4组,分别指示水质属于-中污带、-中污带、寡污带和清洁带,DCCA第一轴可反映水体污染程度,第二轴反映河流的流速.DCCA排序表明,COD与水体污染状况关系最大.物种多样性研究采用9个多样性指数,各多样性指数随水体污染等级加大而呈现下降的趋势.