Comprehensive Management and Protection of Lakes in Kaifeng

Through analysing pollution source and status quo of the main lakes in Kaifeng,such as Dragon Pavilion Lake and Baogong Lake,the conclusion is that Kaifeng＇s lake environment has been in a greater pollution condition. For lake pollution situation,we put forward comprehensive management and protection approaches of lakes,including the relocation of businesses around the lake,plugging the sewage outfall surrounding lakes,dredging and deeply digging to increase the water environment capacity of lake. By dredging the river,the lakes in urban district connect together. Controlling aquaculture scale of lakes,the ecological function of the lake is played. Constructing drainage network around the lake,integration of landscape and lake flood control is formed. Adding new water into lakes,stagnant water becomes flowing water. We sum up the experience of lake management and protection： strengthening protection awareness is the key; lake remediation is the fundamental; attention to ecological protection of the lake is the most important factor in the development of lakes; exploiting a variety of functions of the lakes including landscaping,tourism,recreation,aquaculture,public health is the goal.

The Influence and Implications of Climate Change on Water Quality in a Large Water Reservoir in the Southwest, USA

Maintaining water quality in large reservoirs is crucial to ensure continued delivery of high-quality water to consumers for municipal and agricultural needs. Lake Mead, a large reservoir in the desert southwest, USA, is projected to be affected by both loss of volume and rising air temperatures through the end of the 21st century. In this study, reductions in lake volume, coupled with downscaled climate projections for rising air temperatures through the end of the 21st century, are incorporated into the 3D hydrodynamic and water quality model for Lake Mead. If current management practices continue in the future, simulations indicate water temperatures will increase in all scenarios and could increase by as much 2℃under the most pessimistic scenarios, but nutrient loads would not increase to concerning levels. Releases from the dam to downstream users are projected to be much warmer, and warmer water temperatures and significant dissolved oxygen in the water column are expected to cause challenges for ecosystem and recreation in the future. Surprisingly, during the Winter and Autumn, retention of heat in Lake Mead is more pronounced at higher surface elevations than the lower elevations as expected. The effects of these projections on the lake water quality and consequently, lake management decisions, are discussed.

Effects of artificially induced complete mixing on dissolved organic matter in a stratified source water reservoir

Naturally complete mixing promotes the spontaneous redistribution of dissolved oxygen(DO),representing an ideal state for maintaining good water quality,and conducive to the biomineralization of organic matter.Water lifting aerators(WLAs)can extend the periods of complete mixing and increase the initial mixing temperature.To evaluate the influence of artificial-induced continuously mixing on dissolved organic matter(DOM)removal performance,the variations of DOM concentrations,optical characteristic,environmental factors were studied after approaching the total mixing status via WLAs operation.During this process,the dissolved organic carbon reduced by 39.18%,whereas the permanganate index decreased by 20.47%.The optical properties indicate that the DOM became more endogenous and its molecular weight decreased.Based on the results of the Biolog Eco Plates,the microorganisms were maintained at a relatively high metabolic activity in the early stage of induced mixing when the mixing temperature was relatively high,whereas DOM declined at a high rate.With the continuous decrease in the water temperature,both the metabolic capacity and the diversity of aerobic microorganisms significantly decreased,and the rate of organic matter mineralization slowed down.The results of this study demonstrate that the artificial induced mixing largely enhanced the removal DOM performance by providing a long period of aerobic conditions and higher initial temperature.