River, reservoir and lake sediment contamination by heavy metals downstream from urban areas of Switzerland

This paper quantifies sediment contamination by heavy metals in four reservoirs and one lake located downstream from major urban areas in Switzerland. The waterbodies include the Wettingen Reservoir (located on the Limmat River downstream from Zürich), the Klingnau Reservoir (on the lower Aare River), the Wohlen Reservoir (downstream from Berne), the Verbois Reservoir (downstream from Geneva) and Vidy Bay (Lake Geneva, city of Lausanne). For all sediment cores and contaminants, a trend is observed from high contaminant values in the lower part of the cores, decreasing to lower concentrations in the upper part of the cores. However, for each site and each element, specific features are recognized. Applying the criteria of the Swiss ordinance on soil protection, all sediment cores must be classified as contaminated by one or more contaminants and at variable levels. From these data, it is concluded that: reservoirs and lakes located downstream from major urban centres in Switzerland have accumulated significant volumes of contaminated sediments in the past, representing the largest, but not the most intensely, contaminated sites on a national scale; the main environmental risk is remobilization of the contaminants and their return to the food chain, particularly by infiltration into the groundwater; and although the processes of remobilization are identified, the conditions of occurrence and the amplitude of the processes are still poorly known. Different options of reservoir and lake sediment management also are discussed and further research topics defined.     

Management criteria for lake ecosystems applied to case studies of changes in nutrient loading and climate change

The aim of this paper is twofold: to present and discuss practically useful management criteria from different perspectives of lake management (fishery, recreation, conservation, monitoring of water quality and use of water for irrigation and drinking), and to put these criteria into the context of a holistic lake ecosystem model, LakeWeb, which accounts for production, biomasses, predation and abiotic/biotic feedbacks related to nine key functional groups of organisms constituting the lake ecosystem. These are phytoplankton, benthic algae, macrophytes, bacterioplankton, herbivorous zooplankton, predatory zooplankton, zoobenthos, prey fish and predatory fish. The LakeWeb model also includes a mass‐balance model for phosphorus and calculates bio‐uptake and retention of phosphorus in these groups of organisms. It also includes submodels for the depth of the photic zone and lake temperature. The LakeWeb model is driven by few and readily accessible driving variables and it has been extensively tested and shown to capture fundamental lake foodweb interactions very well, which should lend credibility to the scenarios discussed in this paper regarding the conditions in Lake Batorino, Belarus. The LakeWeb model offers a tool to address important, often very complex, scientific problems in a realistic manner. The first scenario describes the changes after 1990 when there was a drastic reduction in the use of fertilizers in agriculture because of political changes and the corresponding changes in lake characteristics and foodweb structures utilizing the given management criteria. The second scenario describes, for comparative purposes, the probable alterations in the lake foodweb related to global climatic changes; in this case, warming and increased temperature variations. This study indicates that there are several similarities between eutrophication and increases in temperatures, which are discussed in this paper along with the mechanistic reasons related to such changes by using a set of general management criteria.     

对淮河下游治理形势和任务的几点认识

洪泽湖是黄河南下夺淮的产物。新中国成立后通过兴建一系列的控制工程，使其成为真正意义上的一座巨型平原水库，并对淮河下游地区防洪安全和水资源供给产生了巨大影响。深入研究淮河与洪泽湖的关系．对促进淮河下游治理具有现实的意义。     

太湖五里湖生态恢复的理论与实践

在针对太湖五里湖水质严重污染和生态严重退化的情况,从分析浅水湖泊生态恢复的理论入手,提出生态恢复过程中控源减污、生境改善、生态重建、稳态调控的四个关键步骤,评价了西五里湖生态恢复示范工程的效果,计算了示范工程区水生植物覆盖度和生物多样性指数,指出达到景观要求的草型清水稳态湖泊还需要一个漫长的演替过程。     

荆江与洞庭湖汇流区演变分析

 对荆江与洞庭湖汇流区的水沙过程变化及河道演变等进行了分析，认为其主要的影响因素是江湖关系的调整变化、洞庭湖人工围垦和泥沙淤积、江湖汇流区下游河道变化以及上游来水来沙变化等。可供江、 湖治理和三峡枢纽下游河道可能发生的演变及工程措施的研究参考。     

荆江—洞庭湖水沙数学模型研究

在对复杂的荆江—洞庭湖水系进行概化的基础上，根据其中各节点和湖泊的实际情况，建立了对整个荆江—洞庭湖水系进行模拟计算的复杂河网水沙数学模型。采用1996年的相关资料进行了验证，结果表明，模型计算值与实测值吻合较好，说明本文对荆江—洞庭湖复杂边界条件的概化，特别是对湖泊调蓄作用的处理是比较符合实际情况的，模型可以模拟边界条件复杂的河网。运用该模型，可以计算出整个荆江—洞庭湖区域的洪水演进、泥沙淤积和河床变形情况，可供防洪调度以及江湖治理部门参考。     

南水北调东线工程利用南四湖输蓄水对湖区的影响分析

通过预测调水后的蓄水条件变化,对南水北调利用南四湖输蓄水产生的不利影响进行分析,提出了对因输蓄水影响造成的生产、生活设施的损失进行赔偿,对调整渔湖民生产结构适当给予补贴,同时应结合南水北调东线工程的实施,对湖内输蓄水造成的渔具改造、提水站改建、对可能造成水体污染项目的产业控制规模或外迁安置等影响,采取适当的工程或非工程措施加以处理.     

The Fate of Pentachlorophenol in the Bay of Quinte,Lake Ontario

Unfiltered water, surface film, sediment, and biota samples were collected from the Bay of Quinte between May and September 1978 and analyzed for chlorophenols (CPs). Sectioned sediment cores were dated using ²¹⁰Pb and ¹³⁷Cs analyses. Pentachlorophenol (PCP) was found at high concentrations adjacent to a point source and was detected in all compartments examined throughout the bay (a bioaccumulation factor of 10⁴ was observed for PCP in fish). The ratio of 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TTCPs) to PCP increased with distance from the source in the water column and surface film. Photochemical reduction was proposed to account for the phenomenon. CP concentrations in sectioned cores suggested that settling particles adsorb CPs in similar proportion to that observed in the water column and little further change occurs after burial.     

Wave Action and Bottom Shear Stresses in Lake Erie

For Lake Erie, the amplitudes and periods of wind-driven, surface gravity waves were calculated by means of the SMB hindcasting method. Bottom orbital velocities and bottom shear stresses were then calculated using linear wave theory and Kajiura's (1968) turbulent oscillating boundary layer analysis. These calculations were made for south-west and north wind directions and a steady wind speed of 40 km hr^?1. Calculated bottom shear stresses are related to the textural properties of surficial Lake Erie sediments as determined by Thomas et al. (1976). The bottom shear stresses, especially under prevailing southwest wind conditions, control the textural characteristics of surface sediments in Lake Erie. In particular, wave-induced bottom shear stresses are probably the most important energy source for sediment entrainment.