Conservation Grading of Water Ecological Spaces in the Muling River Basin

Along with the urban construction and industrial development, the original continuous riverway of the Muling River has been dammed into river sections of different lengths, which has seriously destroyed ecological environment of the basin. In view of this, it is urgent to protect water ecological environment of the basin. This paper took the national ecological environment conservation instructions as the guidance, combined with the administrative division, planning and actual conditions of the basin, proposed principles and schemes for the grading of water spaces in the basin, as well as the hierarchic control requirements, to provide instructions for the conservation of the river basin.

Community Characteristics of Phytoplankton in Ecological Restoration of Rural Polluted Rivers

The T-type submerged dam based on zeolite and ecological floating bed was set up in Zhujiabang River, a tributary of the Zhihugang River(north of the Taihu Lake), together with ecological restoration measures such as aeration and slope wetland. From the perspective of phytoplankton community, the restorative effect of ecological restoration project on rural contaminated rivers was investigated. The results showed that(i) ecological restoration changed the community structure and succession tendency of phytoplankton, the dominant state of Cyanophyta and Cryptophyta was replaced by some species of Bacillariophyta, Chlorophyta and Pyrrophyta;(ii) ecological engineering restrained the standing stock of phytoplankton community greatly, total biomass of phytoplankton during the restoration period was less than 6 mg/L;(iii) biodiversity of phytoplankton during the ecological restoration maintained at a higher level(mean Shannon-Weiner index was 2.32). Considering the correlation between efficiency of ecological restoration project in purifying water, standing stock of phytoplankton and nutrient level of water, removal of nutrients by ecological restoration project was one of the major factors triggering the change of phytoplankton community characteristics.

Investigation on the eco-toxicity of lake sediments with the addition of drinking water treatment residuals

Drinking water treatment residuals（WTRs） have a potential to realize eutrophication control objectives by reducing the internal phosphorus（P） load of lake sediments. Information regarding the ecological risk of dewatered WTR reuse in aquatic environments is generally lacking, however. In this study, we analyzed the eco-toxicity of leachates from sediments with or without dewatered WTRs toward algae Chlorella vulgaris via algal growth inhibition testing with algal cell density, chlorophyll content, malondialdehyde content, antioxidant enzyme superoxide dismutase activity, and subcellular structure indices. The results suggested that leachates from sediments unanimously inhibited algal growth, with or without the addition of different WTR doses（10% or 50% of the sediment in dry weight） at different p H values（8–9）, as well as from sediments treated for different durations（10 or 180 days）. The inhibition was primarily the result of P deficiency in the leachates owing to WTR P adsorption, however, our results suggest that the dewatered WTRs were considered as a favorable potential material for internal P loading control in lake restoration projects, as it shows acceptably low risk toward aquatic plants.