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Lake Gehu is a representative shallow lake located in the downstream of Yangtze River in China. To identify the phytoplankton community distribution after its treatment,a survey was conducted on the phytoplanktonic community and environmental factors in its north part from January to December in 2013. According to the survey,there were altogether seven phylum,fourtythree genus and sixty-one species of phytoplankton,mainly with Scenedesmus and Cyclotella in spring and winter,Microcystis and Melosira granulata in summer and autumn. The maximum phytoplankton biomass during sampling period was 90. 6 mg / L in August,mainly with Microcystis aeruginosa. The average density of phytoplankton showed a decreasing trend from west to east,with lower vegetation coverage in the open water area. The environmental factor analysis indicated that total nitrogen,total phosphorus and water temperature were key factors that influence the phytoplanktonic density and biomass in this area. Comparing with the average biomass in the water chestnut area and reed area with that in the untreated open water area in the same month,we found that the water chestnut area decreased with the range of 72. 7%-91. 1%,and 63. 9%-83. 7% in the reed area. In August and September when algal bloom occurred in the open water area,the biomass in the chestnut area and in the reed area was only 14. 6% and30. 3% of that in the water area,respectively.

The organic detritus in sediments of the Lake Chaohu were taken as research subject,based on measured total organic carbon in organic detritus. Research was undertaken on the organic detritus of biodegradability and the results of aerobic enhanced degradation of organic detritus,and the degradation effects of organic detritus on different concentrations of organic detritus and aeration rates. The results show the organic detritus has high biodegradability. In about 30 h,reaction reached equilibrium concentration,total removal rate was 50. 69%,and the degradation rate constant K25was 0. 19 h- 1. The concentration of organic detritus and aeration rates have impacts on degradation effect. The method of aerobic enhanced degradation of organic detritus in sediments of the lake is better than traditional method,and provides a new way for the prevention and treatment of black and odorous water.

The removal of organic pollutants, ammonia, and phosphorus from seriously polluted river water has been extensively explored using various traditional integrated constructed wetland systems. However, the removal efficiency of nitrogen was extremely low due to the limited oxygen concentration of these traditional systems. Herein, a novel pilot-scale integrated constructed wetland system (CWs), which consisted mainly of a biotic contacting oxidization pre-treatment (BCO), an artificial aeration vertical sub-surface flow CWs, and a horizontal subsurface flow CWs were applied to enhance the removal of total nitrogen (TN) under high hydraulic loading through artificial aeration. Results showed that, with the application of the novel CW systems, a total of 64.97% removal of TN was achieved with the average inflow of 11.39 mg/L and hydraulic load of 1.67 m3 ⋅ m−2 ⋅ d−1. Further analysis showed that the contributions of BCO, AVFCWs and HF CWs to TN removal were 13.86%, 15.97% and 35.36%, respectively. Besides the TN removal, the CW systems can also obtained about 75% of ammonia removal, within which artificial aeration vertical subsurface flow CWs unit occupied about 60% of contribution. Flowing by the application of this systems, the concentrations of ammonia and nitrate in the outflow decreased to 2.66 and 2.01 mg/L, respectively. The study indicated that the integrated constructed wetland system applied can be an efficiently potential technique for the removal of COD, NH4-N and TP from some rural wastewater.

Lake Fuxian is a representative deep plateau lake located in Yunnan Province, China. To describe crustacean zooplankton’s responses to ecological changes, we carried out studies on its community structure and spatial distribution. Altogether 8 taxa of crustacean zooplankton were founded in Lake Fuxian from June to July in 2005, and the average community density 27.6ind./L dominated by Copepoda. Dominant species of Copepoda were Phyllodiaptomus tunguidus Shen et Tai, and dominant species of cladoceran were Ceriodaphnia cornuta Sars and Bosmina sp. Crustacean zooplankton was mainly distributed from surface to 30m vertically, and its density decreased with the depth increase. Cladocera and Nauplii had the dominance in 0-10m layer, but Copepoda had the dominance when depth down to 10m. Average density of crustacean zooplankton was significantly higher in south lake than north lake (P0.01), while there were no significant differences in average density between near shore region and open water region,and between macrophyte distributed region and no macrophyte distributed region (P0.05). Correlation analysis indicated that there was significant correlation between the vertical density of crustacean zooplankton and algae density or water physical-chemical factors, but there was no significant correlation between the horizontal density and algae density or water physical-chemical factors. Compared with the surveys in 1980s, Neutrodiaptomus mariadviagae mariadviagae (Brohm), one of the dominant species of crustacean zooplankton, disappeared in the lake and was replaced by P. tunguidus, which was probably caused by introduction of Neosalanx taihuensi Chen. The density of crustacean zooplankton showed an increasing tendency, but that was still rather low, likely a result of increased nutrient levels and predation by N. taihuensi.

The spatial distribution, temporal changes of water transparency and their influencing factors in Lake Fuxian, a deep lake in Yunnan Plateau, were analyzed according to the investigations during June-July in 2005 and the regular monitoring data since 1980. The Secchi disk transparency varied from 0.5-6.2m with an average value of 4.6m in Lake Fuxian during June-July in 2005, The spatial distribution pattern of transparency was: north areasouth area, littoral zonepelagic zone, and very low in the estuary area. Suspended solid and algae were the main influencing factors on spatial distribution of water transparency which decreased with their increase. In the last 20 more years, water transparency in Lake Fuxian showed decrease trend, and the increase of algae was the main direct influencing factor. The increase of total nitrogen and total phosphorous was the important indirect influencing factors which could lead to algae multiplication.

On August 2006, grave soils from organic and conventional farming were sampled within the watershed of Fuxian Lake in Yunnan Province. Soil granule composition, heavy metal contents and nutrition accumulation in the soil profile were determined. Nitrogen and phosphorus losses from the soils were assessed by the in-door rainfall simulation. The results were as below: 1) both organic and conventional farming practices significantly lower the soil sand content on the 0-20 cm soil profile; 2) all soil heavy metal contents met the Class A standard of National Environment Quality Standard for Soils (GB/15618-1995) except Cd which only met Class B standard; 3) soil total nitrogen and organic matter accumulated in the 0-20 cm soil profile, and showed no significant differences between organic and conventional farming practices. The accumulation of soil total phosphorus, NO3-N and water dissolved phosphorus (WSP) under the organic farming practice is significantly higher than those under conventional farming practice; and 4) under the condition of 780 mm rainfall simulation, the risk of nitrogen and phosphorus losses from the organic farming soil is higher than that from the conventional farming. Total amount of nitrogen and phosphorus losses from the organic fanning soil were 1.9 and 19.8 times higher than those from the conventional farming soil, respectively.

A concept Aerated Vertical-Flow Wetland is introduced in the text,experimental researches through a pillared unit were carried out on the performances of treating domestic wastewater in the rural area of Lake Dianchi valley,Yunnan province.The oxygen transfer efficiency of the experiment device reached 14.04%.And the experiment data showed that,with hydraulic loading as 15.29m~3/(m~2·d)and airflow-waterflow ratio 1:2,average BOD_5 and NH_4-N removal respectively reaches 74.4% and 63.5%.The BOD_5 and NH_4-N values within outflow get to 4.96mg/L and 2.72mg/L.It resulted that,the Aerated Vertical-Flow Wetland Technics was effective and economical for suburb domestic wastewater treatment with high hydraulic loading.

A total of 37 species of fishes belonging to 32 genera and 15 families were collected and identified in Lake Fuxian from March 2004 to July 2005. Among them, 14 species belonged to indigenous fishes and 4 species were endemic to this lake. The main fishes in the catch were Neosalanx taihuensis Chen, Spinibarbus yunnanensis Tsu, Silurus grahami(Regan) , Pelteobagrus fulvidraco(Richardson) and Carassius auratus auratus (Linnaeus). There were great changes on community structure of fish fauna in Lake Fuxian, and the resources of the indigenous fishes such as Anabarilius grahami (Regan) decreased severely. Compared with the survey offish species made in 1995,11 indigenous species were not collected in Lake Fuxian, while 5 species were found at first.

Plant material decomposition experiment was carried out in room condition from 1998 to 1999 (lasted for 12 months). The plant material and top layer sediment was collected from East Taihu Lake, Jiangsu Province, China. Three ecotypes of aquatic plant were used: emerged plant ( Zizania latifolia ), floating leafed plant ( Nimphoides peltatum ), and submerged plant ( Vallisneria spiralis, Potamogeton maackianus ). It resulted that, floatnig leafed plant had the highest decomposition rate and annual reduction ratio. Submerged plant had high decomposition rate in the early stage and the lowest annual reduction ratio. The decomposition process of emerged plant was very lengthy. By the end of the experiment, more than 70% of the bio material was reduced by decomposition for emerged and floating leafed plant, but less then 50% for submerged plant. Phosphorus release was prior to TOC in the decomposition process. It means that most of the phosphorus in the plant material can be released to the water when aquatic plants die down in the winter. Nitrogen was released from the plant material parallely to TOC reduction, and nitrogen content ratio in the plant material nearly kept constant in the decomposition process for emerged and floating leafed plant.

Nine sediment-water columns were taken from three stations of East Taihu Lake (about lm in depth) in June, 1997. The overlying water of the cores was filtered (0. 45m), and then the cores were placed in a dark room for 50 days. Air-bubbling was used to keep oxidized conditions in the overlying water and upper sediment, without resuspending the sediment. The room temperature was between 23. 5 and 31. 2, and the pH value of the overlying water and upper sediment was 7. 2 0. 2. Concentration of PO_4~3-P in the overlying water was measured every 2 or 3 days to follow the P-release process. In the first 15 days, PO_4~3 -P level in the overlying water increased 2 orders of magnitude. But in the following 33 days, the PO_4~3-P level decreased 1 order of magnitude and then stabilized. Such a process was also found in the West Lake, Hangzhou and Gehu Lake, Changzhou. We think it not a normal sediment-P-release process, but more complex as follows. In natural conditions of East Taihu Lake, the sediment is covered by a layer of detritus. Biological degradation is so intensive in this layer that PO_3~4 accumulates to a high level and diffuses to both the overlying water and the sediment beneath it. In the sediment a steep PO3~4 -P concentration gradient forms because of the high diffusive resistance. But in the overlying water, PO_4~3-P is used by aquatic plants and is kept at a low level. We are not able to measure PO_4~3-P concentration in the detritus layer, but an indirect evidence was found in the same lake: a PO_4~3- P concentration gradient from 200mg m_~3 in the upper sediment layer to 80mg m_~3- in the sediment of 18cm depth existed when PO_4~3-P concentration in the overlying water was only 22 mg m_~3. In the core experiment, phosphorous biological cycling was broken when phytoplankton was removed from the overlying water by filtration, and thus, PO_4~3- accumulated in the water quickly; After 15 days, the p-release reaction in the detritus layer was about to end, and p-diffusion from overlying water to the sediment triggered. In East Taihu Lake and the other similar lakes with stable bottom conditions, detritus layer may exist and affect p-release core experiment seriously. In such a situation, it is better to measure internal-P-loading by other means, such as whole lake p-budget and in-situ enclosure experiment.