Pan Jizheng

Spatial-temporal dynamic changes of the water transparency and their influencing factors in Lake Fuxian, Yunnan Province

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.

Risk assessment on soil environment quality and losses of nitrogen and phosphorus for the gravel soils under different farming practices in the watershed of Lake Fuxian

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.

Low concentration of phosphorus removal in waters with CaO 2

Aiming at the advanced purification of low concentration of phosphorus in natural water,the adsorption of phosphate by CaO2 was studied using the models of adsorption kinetics and adsorption isotherm,and the influence of different operating parameters on the phosphorus removal was investigated. The results showed that:( 1) The experimental data for the process of phosphate uptake onto CaO2 fit the Langmuir isotherm mode,and the maximum adsorption capacity was 381. 7 mg / g( 25℃).( 2) Thermodynamic parameters in the process of phosphorus removal are ΔG0 0 and ΔH0 0,while the process was a spontaneous exothermic one.( 3) The adsorption performance of CaO2 was evaluated by the pseudo-second-order reaction rate equation,when the adsorption rate increased with the increasing concentration of phosphate in the solution,and the adsorptive reaction reached equilibrium in 4 minutes.( 4) The optimized effect of phosphorus removal was obtained at p H = 8.( 5) Among the high concentrations of coexisting anions,the CO2-3expressed the greatest influence on phosphorus removal of CaO2 and could make the adsorption capacity reduce 14. 7% under the concentration of 10 times.

Spatio-temporal distribution of phytoplankton and environmental factors in the north part of Lake Gehu( Jiangsu) after muti-treatment

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.

Aerobic enhanced degradation of organic detritus of lacustrine sediments

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.

Preliminary study on the optical properties of Lake Gehu

Seasonal variations of the optical parameters and physicochemical properties of lake water at 15 sampling sites were investigated,from July 2009 to June 2010,to provide the basic lake optical properties data for submerged aquatic vegetations restoration of a shallow lake—Lake Gehu. The annual variation of the attenuation coefficient of photosynthetically active radiation( Kd)was 1. 32-17. 42 m- 1. The minimum and maximum values of Kdwere observed in autumn( 1. 32-3. 70 m- 1) and summer( 3.68-17.42 m- 1),with a medium value of2.35 m- 1and 6. 23 m- 1,respectively. The average euphotic zone depth in spring,fall and winter can satisfy the demand of submerged aquatic vegetation. However,the average euphotic zone depth was only 0. 84 m in summer,which was less than the average water depth( 1. 20 m) of Lake Gehu and implied that the photosynthetically active radiation was one of the inhibiting factors to restore the submerged aquatic vegetations in summer. The Kdand secchi disk depth( SD) in fall and winter had the relationship of Kd= 2. 089 + 0. 705 /SD. Chlorophyll-a and suspended solid were the factors influencing the Kdvalue in Lake Gehu.

Community structure and spatial distribution of crustacean zooplankton in Lake Fuxian, Yunnan, China

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.