2010年洱海全湖磷负荷时空分布特征

为探讨不同来源磷负荷对洱海水体富营养化的贡献,研究了洱海入湖河流、干湿沉降和沉积物内源释放等来源磷负荷的时空变化特征. 结果表明:2010年洱海磷负荷的主要来源是入湖河流,其所带来的磷负荷占总入湖负荷的33%. 入湖河流磷负荷与洱海水体富营养化指数呈显著正相关,并且季节性变化明显,10月是高峰期入湖河流磷负荷区域差异较大,北部3条河流是主要来源,其中以弥苴河入湖磷负荷最大,占入湖河流磷负荷总量的52%. 沉积物磷扩散通量由北向南呈下降趋势,最高值在湖心区,11月最大. 干湿沉降入湖磷负荷季节性变化明显,干沉降占干湿沉降入湖磷负荷总量的47%. 外源入湖磷负荷控制,应以雨季之初为关键时期,以弥苴河及其流域为重点区域,以坝区农业污染控制为重点,同时应加强湖泊水体生态修复控制沉积物内源磷释放. 

Characteristics of Temporal and Spatial Distribution of Phosphorus Loading in Erhai Lake in 2010

The source contributions of phosphorus loading on the eutrophication in Erhai Lake was studied by analyzing the temporal and spatial variations of phosphorus loading. The sources included the rivers flowing into the Erhai Lake, dry and wet depositions, and sediment releases. The results indicated that rivers into the Erhai Lake were the main source of phosphorus loading, which contributed 33% and showed a significant positive correlation with the eutrophication index in 2010. The phosphorus loading of rivers into the lake varied significantly with seasonal changes, reached the peak value in October, and largely showed regional differences. The three rivers in the North were the main source, and the Miju River provided the greatest contribution with 52% of the phosphorus loading among rivers into the lake. The diffusion flux of sediment phosphorus release decreased from the north to the south. The highest value of sediment phosphorus release was found in the center district, and it''s maximum value was in November. The phosphorus loading of the dry and wet deposition into lake changed significantly between different seasons, and the phosphorus loading of the dry deposition contributed a proportion of 47% to the total phosphorus loading of dry and wet deposition into lake. The critical period would be selected at the beginning of the rainy season to control of external phosphorus loading into the Erhai Lake, while the Miju River and its watershed should be treated as the key areas. In addition, the agricultural pollution in the dam area would be the key control point and the ecological restoration should be applied to control the endogenous sediment phosphorus release.