A study of phosphorus species in the surface sediment of Lake Hongjiannao,Shaanxi Province,Northwest China
Background,aim,and scope Phosphorus is an important essential element for life.Together with nitrogen,it is also an important element that cause water eutrophication.In the lake environment,the risk of phosphorus release from the sediment to the water is closely related to the occurrence form of phosphorus in the sediment.The more the active form of phosphorus,the easier the phosphorus releases to the water environment.In addition,phosphorus also has a great influence on the form and abundance of nitrogen in the environment.As the largest desert freshwater lake in China,Lake Hongjiannao is an important habitat for Larus relictus.Therefore,the study of phosphorus form in lake sediment is of great importance to evaluate the eutrophication risk of lake water.Materials and methods In order to characterize various phosphorus species in the sediment,a total of 12 samples from Lake Hongjiannao and 5 samples from rivers entering the lake were collected and treated using a sequential extraction method improved by Hupfer et al.(1995).The content of phosphorus in the extracted solution was determined by the Mo-Sb anti-spectrophotometry method.Results The mean of five phosphorus species in the surface sediment samples of Lake Hongjiannao are:NH4Cl-P 3.55 mg ∙ kg-1,BD-P 35.63 mg ∙ kg-1,NaOH-P 42.57 mg ∙ kg-1,HCl-P 144.45 mg ∙ kg-1 and Res-P 227.90 mg ∙ kg-1.In the sediment of Lake Hongjiannao,phosphorus is mainly present in the form of non-reactive HCl-P and Res-P,while the contents of soluble reactive NH4Cl-P and BD-P are low.Except for NaOH-P and HCl-P,the variation of other phosphorus species at different sampling sites was not significant.Discussion The spatial analysis shows that the distribution of NH4Cl-P and BD-P has roughly similar characteristics,and there is a high value in the centers of eastern and western simi-lakes respectively.NaOH-P is mainly enriched near the south bank of the lake.Interestingly,the distribution of HCl-P and Res-P showed roughly opposite trends.TP is almost evenly distributed in the whole lake.Based on comparison with other lakes in China,TP content in the surface sediment of Lake Hongjiannao is lower than that of other lakes,except for the Chaohu Lake and Poyang Lake in the Yangtze River Basin.According to comparison of the contents of soluble reactive phosphorus with other lakes,the contents of NH4Cl-P,BD-P and NaOH-P in Lake Hongjiannao are also at a lower level.Conclusions The risk of phosphorus release from the surface sediment to the water in the Lake Hongjiannao is generally low,but the risk of the release of some alkaline dissolved phosphorus is likely to increase under the trend of alkaline enhancement.The relationship between the spatial distribution of different phosphorus species and lake hydrodynamics,grain size of sediment and so on remains to be further studied.Recommendations and perspectives The results in this study are valuable for evaluating the potential risk of phosphorus release of surface sediment to the lake water and the eutrophication of lakes in the climatic sensitive zone.
Lake Hongjiannaosurface sedimentphosphorus speciesrelease risk
万方数据
维普
