Preliminary Report on the Successful Breeding of the Endangered Fish Sinocyclocheilus grahami Endemic to Dianchi Lake

The fish Sinocyclocheilus grahami is one of the indicative and endemic species in the Dianchi Lake ecosystem. As a result of pollution and invasion of exotic fishes, the fish had disappeared from Dianchi Lake since 1986 and only a few small populations survive in springs and streams around the lake. Due to the endangered status and special scientific value, S.grahami was listed as the second class protective animal of China in 1989. The importance of S. grahami and the indigenous biodiversity of Dianchi Lake were recognized by the Global Environment Foundation （GEF） /World Bank and Yunnan Development ＆ Reform Committee. Therefore a special grant was set up to restore and conserve the indigenous biodiversity of Dianchi Lake. The artificial breeding of S. grahami is a part of the targeted activities. Two successful breeding experiments were achieved using five females plus six males up to early March 2007. Approximately 1600 eggs were collected, of which 1320 eggs fertilized using the dry-fertilizing method. The mean fertilization rate was 73%. Approximately 480 fish fry was hatched and the mean hatching rate was 36%. After 10 days of cultivation, 95% fingerlings survived and their body lengths were up to 8- 12 mm. The importance of the artificial breeding success of S. grahami could be summarized as following： effectively protecting the fish from extinction; releasing the fish fry back to appropriate water body of the lake could help to restore the indigenous biodiversity of Dianchi Lake; facilitating the shift of local fish cultivation from the present non-indigenous to the future indigenous fishery.

Evaluation on Non-use Value of Dianchi Lake Wetland Using CVM

[Objective] This study was to analyze the personal Willingness to Pay （WI-P） on the non-use value of Dianchi lake wetland and the influential factors. [Method] Questionnaire was designed according to the Contingent Valuation Method （CVM） to investigate people of different occupations at different ages, based on which the evaluation on non-use value of Dianchi lake wetland was carried out. And the relationship between WTP and social characteristics were analyzed by using non- parametric estimation. [Result] The average WTP on Dianchi lake wetland is 150.03- 217.66 yuan per person every year, and the total WTP is 626-909 million yuan ev- ery year. Age, education and residence of the respondents have remarkable influ- ence on the VVTP. The influence of education level and residence on option value is significant; bequest value is significantly correlated with age; while there is no significant relationship between existence value and social characteristics. [Conclusion] The evaluation on the non-use value of Dianchi lake wetland is important for the scientific development and utilization of wetland resources.

Assessment of water pollution control strategies: a case study for the Dianchi Lake

Lake eutrophication has increasingly become a major environmental issue in China. Although significant efforts have been made towards its resolution in the last decade, most of the implemented control strategies are fragmented, and the formation of policy lacks of sound scientific basis and long\|term objectives. Taking the well\|known Dianchi Lake as a case study, this paper presented a comprehensive assessment for the effectiveness of various eutrophication control strategies. It is expected that the concluding lessons would have a major implication to future eutrophication control.

AAssessment of the spatial-temporal eutrophic character in the Lake Dianchi

Water-quality deterioration and eutrophication of the Lake Dianchi have acquired more and more attention in the last few decades. In this paper, the spatial and temporal eutrophication status of the Lake Dianchi was assessed. The comprehensive trophic state index was chosen to assess the trophic status of the Lake Dianchi in the past 13 years. The result reveals that the trophic condition of Caohai is more serious than that of Waihai. Most of time Caohai was in extremely hypereutrophic state from 1988 to 2000. The trophic condition of Waihai had a worsening tendency from 1988 to 2000. Waihai was in eutrophic state before 1995, but it got in a hypereutrophic state after 1995. It was pointed out that TN and TP were the two biggest contributors of CTSIM in both Caohai and Waihai.

Fractionation of Heavy Metals in Sediments from Dianchi Lake,China

Fractionation of heavy metals in sediments can help in understanding potential hazards of heavy metals. The present study analyzed total concentrations and fractions of selected heavy metals （Cd, Cr, Cu, Pb, and Zn） in surface sediments from Dianchi Lake, Yunnan Province, China, as well as factors that may affect distributions of the various heavy metal fractions. Total concentrations of the heavy metals decreased in the order Zn 〉 Cu 〉 Pb 〉 Cr 〉 Cd. These heavy metals, except Cr, were much higher than their background levels, indicating that Dianchi Lake was polluted by Cd, Zn, Pb, and Cu. Cadmium occurred mainly as the non-residual fraction （sum of the HOAc-soluble, reducible, and oxidizable fractions） （97.6%）, and Zn （55.7%） was also predominantly found in the non-residual fraction. In contrast, most of the Cr （88.5%）, Pb （81.8%）, and Cu （59.2%） occurred in the residual fraction. Correlation analysis showed that total heavy metal concentrations, organic matter and reducible Fe were the main factors affecting the distributions of the various heavy metal fractions. In the Walhai section of Dianchi Lake （comprising 97% of the lake area）, the concentrations of Cd, Zn, Pb, and Cu in the non-residual fraction were significantly lower （P ≤ 0.01 or 0.05） than those of the Caohal section （3% of the lake area）. This indicated that potential heavy metal hazards in the Caohai section were greater than the Waihai section.

Phosphorus in Interstitial Water Induced by Redox Potential in Sediment of Dianchi Lake,China

The sediment redox potential was raised in the laboratory to estimate reduction of internal available phosphorus loads,such as soluble reactive phosphorus(SRP)and total phosphorus(TP),as well as the main elements of sediment extracts in Dianchi Lake.Several strongly reducing substances in sediments,which mainly originated from anaerobic decomposition of primary producer residues,were responsible for the lower redox potential.In a range of -400 to 200 mV raising the redox potential of sediments decreased TP and SRP in interstitial water.Redox potentials exceeding 320 mV caused increases in TP,whereas SRP maintained a relatively constant minimum level.The concentrations of Al,Fe, Ca^(2+),Mg^(2+),K^+,Na^+ and S in interstitial water were also related to the redox potential of sediments,suggesting that the mechanism for redox potential to regulate the concentration of phosphorus in interstitial water was complex.

Development and application of a two-dimensional water quality model for the Daqinghe River Mouth of the Dianchi Lake

Water quality models are important tools to support the optimization of aquatic ecosystem rehabilitation programs and assess their efficiency. Basing on the flow conditions of the Daqinghe River Mouth of the Dianchi Lake, China, a two-dimensional water quality model was developed in the research. The hydrodynamics module was numerically solved by the alternating direction iteration （ADI） method. The parameters of the water quality module were obtained through the in situ experiments and the laboratory analyses that were conducted from 2006 to 2007. The model was calibrated and verified by the observation data in 2007. Among the four modelled key variables, i.e., water level, COD （in CODcr）, NH4＋-N and PO43-P the minimum value of the coefficient of determination （COD） was 0.69, indicating the model performed reasonably well. The developed model was then applied to simulate the water quality changes at a downstream cross-section assuming that the designed restoration programs were implemented. According to the simulated results, the restoration programs could cut down the loads of COD and PO43-P about 15%. Such a load reduction, unfortunately, would have very little effect on the NH4^＋-N removal. Moreover, the water quality at the outlet cross-section would be still in class V （3838-02）, indicating more measures should be taken to further reduce the loads. The study demonstrated the capability of water quality models to support aquatic ecosystem restorations.

Bird diversity and waterbird habitat preferences in relation to wetland restoration at Dianchi Lake, south-west China

Background:Restoration projects have been implemented worldwide to mitigate the adverse effects of the loss and degradation of wetland habitats.Much research has been carried out on the impacts on birds of wetland restoration and management projects in China. Studies have mainly investigated central or coastal wetlands,while inland wetlands in remote areas have been much less studied. We focused on examining the response of wild birds to wetland restoration in Dianchi Lake,south-west China. Methods: The line transect method was performed at 26 sampling plots.Three of these were in the city,and to acquire all wild bird data 23 plots were located every 2-8 km along the shore of Dianchi Lake, between December 2011 and November 2013.We collected all related bird records by searching the available literature, articles, newspapers and records of birdwatchers to compare species variation before and after implementation of wetland restoration.To measure the relationships between waterbird assemblages and habitat structures, we used canonical correspondence analysis (CCA) to pair the main matrix of bird assemblages with a second matrix of habitat variables. Results: We recorded 182 bird species belonging to 51 families and 17 orders. Of the species, 42 were new records for Kunming City and 20 were new records for Yunnan Province. Ten waterbird species were found to have disappeared from the shore of Dianchi Lake.CCA results indicated that waterbirds could be divided into four categories based on their habitat preference:synanthropic (wintering gulls), special habitat (shorebirds),semi-natural (wintering coots and ducks) and disturbance-tolerant (resident) species.Conclusions:Our study is the first to consider the entire wild bird community throughout the year and discuss the species variation before and after wetland restoration projects launched for Dianchi Lake.Distinct habitat requirements of different waterbird groups were detected in our study,suggesting different types of restoration and management should be implemented.

Lake Sediments from Dianchi Lake:A Phosphorus Sink or Source?

Dianchi Lake is a highly eutrophic lake in southwestern China where phosphorus (P) is the limiting element for eutrophication and where lake sediments play an important role in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 to investigate the P loading of the lake sediments, while fresh surface sediments were studied in the laboratory to clarify its role for phosphorus. The results showed that concentrations of total phosphorus (TP) in sediments were very high, with a maximum value of 6.66 g kg-1, and decreased with sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher in acidic than in alkaline conditions. The release experiments showed that P release increased as pH rose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higher under anaerobic conditions, especially with low P content in the lake water. At present, the sediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water. However, if the external P load was reduced and P content in lake water became low, the sediment would have a large potential for P release under anaerobic conditions.

New Normal Control of Agricultural Non-point Source Pollution in the Dianchi Lake Basin

Based on Kunming statistical yearbook and field survey data of agricultural non-point source pollution in counties or districts in the Dianchi Lake basin,previous and current situation of agricultural production and agricultural non-point source pollution control in the Dianchi Lake basin were studied,and countermeasures and suggestions of comprehensive control of agricultural non-point source pollution in the basin were proposed.

Estimate of ammonia transfer from Lake Dianchi water to the air

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Regime shift in Lake Dianchi(China) during the last 50 years

Lake Dianchi has undergone accelerated alternations resulting from human activities during the last 50 years, and provides an exceptional example for the study of regime shift in a shallow lake. Focusing on regime shift, we systematically studied and analysed alternations of key components of its ecosystem, including water parameters, phytoplankton and zooplankton biomass, macrophyte composition and fish populations. We found that the shifting course of Lake Dianchi went through three major phases, corresponding to three distinct states: Phase I clean, stable state during the 1950 s; Phase II transitional state during the 1970 s–1980 s; and phase III stable, turbid state since 1993. We analysed all data and samples, identifying the threshold concentrations at which regime shift occurred: total nitrogen(TN) and phosphorus(TP) reaching 1.2 mg/L and 0.13 mg/L, respectively. Results from this study strongly suggest that the increasing input of external nutrients, reclaiming land from the lake and foreign fish invasion were major inducements to the accelerated shift of Lake Dianchi to its turbid, stable state. These findings provide valuable guidelines for potential efforts to reverse this unnatural process in Lake Dianchi. The restoration may need to:(1) thoroughly and accurately identify pollution sources to control and reduce excessive external nutrients flowing into the lake;(2) return reclaimed land to the lake and recover the littoral zone to its natural state to facilitate increased restoration of macrophytes; and(3) strategically adjust fish populations by reducing benthivorous and filter-feeding fish populations that prey on zooplankton, while enlarging zooplankton populations to control phytoplankton biomass.

Internal Loads and Bioavailability of Phosphorus and Nitrogen in Dianchi Lake,China

Sediments have a significant influence on the cycling of nutrient elements in lake environments. In order to assess the distribution characteristics and estimate the bioavailability of phosphorus and nitrogen in Dianchi Lake, organic and inorganic phosphorus and nitrogen forms were analysed. The 210 Pb radiometric dating method was employed to study temporal changes in the phosphorus and nitrogen pools in Dianchi Lake. The result show that the total phosphorus(TP) and total nitrogen(TN) were both at high concentrations, ranging from 697.5–3210.0 mg/kg and 1263.7–7155.2 mg/kg, respectively. Inorganic phosphorus(IP) and total organic nitrogen(TON) were the main constituents, at percentages of 59%–78% and 74%–95%, respectively, in the sediments. Spatially, there was a decreasing trend in phosphorus and nitrogen contents from the south and north to the lake centre, which is related to the distribution pattern of local economic production. The burial rates of the various phosphorus and nitrogen forms increased in same spatially and over time. Particularly in the past two decades, the burial rates doubled, with that TN reached to 1.287 mg/(cm^2·yr) in 2014. As the most reactive forms, nitrate nitrogen(NO_3-N) and ammonia nitrogen(NH_4-N) were buried more rapidly in the south region, implying that the potential for releasing sedimentary nitrogen increased from north to south. Based on their concentrations and burial rates, the internal loads of phosphorus and nitrogen were analysed for the last century. A TP pool of 71597.6 t and a TN pool of 81191.7 t were estimated for Dianchi Lake. Bioavailable phosphorus and nitrogen pools were also estimated at 44468.0 t and 5429.7 t, respectively, for the last century.

Modern Sedimentation of Phosphorus and Its Microbial Decomposition and Concentration: An Example from Dianchi Lake, Yunnan, China

Dianchi Lake is one of the lakes with the richest phosphorus source in the world, in which the P2O5 content in the bottom sediments reaches averagely 0.51 wt % and maximally 1.92%. Studies indicate that this: extremely P-rich state is attributed mainly to the large volume (as high as hundred thousands of tons) of phosphatic matter coming into the lake as many rivers feeding the lake pass through a vast area of phosphate-mining districts, which then undergo weathering and particularly some human activities, including waste water discharge. When phosphatic matter enters the lake, its grained parts are firstly decomposed by phosphorus-decomposing bacteria, and finally accumulated in some geographically special parts of the lake, such as a bay area where water flow is much more slower than elsewhere in the lake. With the involvement of phosphorus-concentrating bacteria, the accumulated phosphates in the bottom sludge ultimately form phosphate minerals through deep-burial diagenesis.

General Thinkingon the Management of Blue Algae Outbreak in the Taihu Lake,the Chaohu Lake and the Dianchi Lake

Among the Chinese lakes with the problem of eutrophication, the Taihu Lake, the Chaohu Lake and the Dianchi Lake have the worst cases of blue algae outbreak, which happen every year. Other lakes also have problems of blue algae outbreak at various degrees. However, some lakes don＇t have such problems. Practices have shown that through comprehensive management, the problem can be basically eliminated or significantly alleviated. ＂Water bloom＂ and blue algae outbreak have different connotation. The major factors affecting blue algae outbreak are sources of pollutants and ecological environment. Experiences are summed up and a new thinking on its management is developed： resolving the problem of blue algae is fundamental to lake management and development goals should be clearly set forth so as to eventually build a healthy aquatic ecosys- tem. The problem of blue algae can＇t be fully tackled by solely relying on the management of eutrophication but only by combining efforts of reducing the amount of blue algae and the management of eutrophication. The number of reduced blue algae should be larger than that of naturally prolifera- ted algae so as to alleviate and eliminate the problem of blue algae outbreak. Various engineering and technical measures and relevant protective procedures should be carried out in a scientific and proper manner. The total amount of nitrogen and phosphorous entering the lake either from point-source or non-point source pollution should be substantially reduced. Controlling the source of pollution and intercepting pollutants are the bas- ic measures. Wastewater treatment plant is the largest point source pollution in the future and adequate plants should be built with improved emission standards. Meanwhile, other measures including fishing out blue algae, diverting water, dredging, ecological restoration and expanding reed zone, should be implemented to alleviate the problem of eutrophication and eventually eliminate the problem of blue algae outbreak.

GIS Based Evaluation System for Ecological Constraints of Dianchi Lake Basin

With the advance of urbanization process and rapid growth of urban population,the construction land scale in Dianchi Lake basin increases at a sharp speed.Due to lack of reasonable scale control and space optimization,many areas have the problem of blind growth in construction land.On the one hand,it results in deterioration of regional ecological environment.On the other,it poses hidden danger for sustainable land use in the basin.Therefore,in order to coordination of regional land use and ecological environment construction,this paper on the basis of the existing various zoning method,the natural ecological conditions and resources environment as the constraint conditions of regional ecological balance,puts forward the Dianchi lake watershed ecological constraint type classification method based on GIS,and discusses the evaluation unit division,index selection and handling technical issues.Through evaluating ecological constraints of Dianchi Lake basin,this study divided Dianchi Lake basin into extremely high,higher,high,medium and low ecological constraint zones.Finally,it came up with guiding and regulating measures for land use of each type of ecological constraint,in the hope of providing scientific basis for optimum allocation of land resources in Dianchi Lake basin.

Measuring benefits of Dianchi Lake wetland based on GIS RS GPS technology

Based on the collection data of the plants, water quality, soils of Dianchi Lake, and combined high resolution satellite remote sensing images, the paper analyzed evolution law of Dianchi Lake wetland, and evaluated the benefi ts of Dianchi Lake wetland from the perspective of economy, environment, society and zoology. The results showed that the area of wetland and plant community account for 92.2% in lakeside zone, the increase was 141.4% compared with the value of 2007. The total value of evaluated benefi ts of Dianchi wetland increased 3.439 billion yuan, and ecological environment improved gradually.

Pollution Control Programs of Large-Scale Livestock and Poultry Farms in the Dianchi Lake Basin

With the enlarging scale and intensifying production of livestock and poultry breeding, the environment pollution becomes increasingly prominent in the Dianchi Lake Basin since 1990s. According to the survey of ＂The First National Census of Pollution Sources＂, occurrence and discharge of pollutants in large-scale livestock and poultry farms in this region were first understood. The pollution characteristics of large-scale live- stock and poultry breeding were also analyzed deeply. On this basis, the significance of pollution control programs for environment protection was investigated from aspects of pollution control policy, technology management and publicity.

Simulation and Prediction on Space-Time Distribution of Water Quality in Dianchi Lake

It is very important in pollution treatment to clarify the space-time distribution of water quality in Dianchi Lake. Based on the sample data obtained from 10 observation stations every month from 2008 to 2009, it uses space-time semi-variogram and ordinary kriging method to simulate the space-time variance and distribution of water quality indictors (TN, TP, BOD, CODMn, DO, Chlorophyl-α, etc.). Because the space-time semivariogram also has a certain of ex-trapolation function. From the simulation results, the pollution is mainly concentrated at the North (Caohai) and the Southwest area (Haikou), and water pollution has a increase trend.

Study on Control Scheme for Nonpoint Source Pollution in Dahe Reservoir Water Source Protection Area of Dianchi Lake Basin

[ Objective] The research aimed to study control scheme for nonpoint source pollution in Dahe Reservoir water source protection area of Dianchi Lake basin.[ Method] On the basis of the SPOT5 satellite remote sensing imagery in 2010 and field investigation of GPS record, ecological design for nonpoint source pollution control in Dahe Reservoir water source protection area of Dianchi Lake basin was conducted. Then, the effects of optimization measures were evaluated by the reductions of N and P outputs on different land-use types. E Resultl Control functions of the water source protection area on soil erosion and the emissions of N, P and other pollutants would be promoted after optimization. The optimization meas- ures had a significant effect for prevention and control of the non-point source pollution in the water source protection area. [ Conclusion] The re- search provided scientific basis for promoting ecological construction of the small green basin in Dahe Reservoir water source protection area of Di- anchi Lake basin.