滇池湖滨缓冲带和农田土壤无机磷分布及淋失特征

Distribution and Leaching of Inorganic Phosphorus in Soils of the Lakeshore Buffer Zone and Farmlands Around Lake Dianchi

  • 摘要: 为了明晰滇池湖滨土壤磷素分布状况,评估其淋失特征,对昆明市滇池南部湖滨缓冲带及农田Ⅰ(邻近缓冲带)和农田Ⅱ(离农田Ⅰ约1.5km)剖面土壤理化性质、磷素分布特征及其与地下水关系进行研究。结果表明:湖滨缓冲带土壤有机碳和全氮含量均显著高于农田土壤,缓冲带土壤浅表地下水中COD和总磷含量也显著高于农田Ⅱ。湖滨缓冲带土壤0~40CM土层全磷含量与农田土壤的差异不显著,但有效磷(Olsen-P)含量显著低于农田土壤。Ca-P是滇池湖滨土壤无机磷的主要组分,占无机磷总量的63%~69%。湖滨缓冲带土壤O-P含量及其占无机磷总量比例显著高于农田土壤,而AI-P和Fe-P含量及其占无机磷总量比例则显著低于农田土壤,表明缓冲带建设已经导致湖滨土壤无机磷组分及分布呈现明显分异。相关分析显示,湖滨浅表地下水埋深与其COD和总磷含量呈极显著负相关关系,同时表层(0~20cm)土壤Olsen-P、AI-P和Fe-P含量与地下水总磷含量也存在显著或极显著负相关关系。这表明土壤表层是滇池湖滨区土壤磷素淋失的主要层次,而浅表地下水埋深是影响湖滨区土壤磷素淋失的重要因素之一。

     

    Abstract: In order to get to konow how soil phosphorus is distributed in and leached from the soils around Lake Dinachi,soil samples were collected from the lakeshore buffer zone and farmlands around the lake for analysis of physicochemical properties,distribution of soil phosphorus and its relationship with groundwater.Results show that soil organic carbon and total nitrogen was higher in the buffer zone than in the farmland,and so was COD and total phosporus in shallow groundwater.No significant difference was observed between the soils of the lakeshore buffer zone and the farmland in total phosphous concentration in the 0-40 cm soil layer,however,the former was much lower than the latter in Olsen-P concentration.Ca-P was the dominant fraction of inorganic phosphorus in the buffer zone soil,accounting for 63%-69% of the total inorganic phosphorus.The buffer zone soil was also apparently higher than the farmland soil in proportion of O-P to soil total inorganic phosphorous,but much lower in proportion of Al-P and Fe-P.All these indicate that the 3 years of buffer zone construction has led to apparent differentiation of fractionation and distribution of inorganic phosphorous in the soils around the lake.Correlation analysis shows that depth of shallow groundwater table was in extremely significant negative relationship with COD and total phosphorus in the groundwater,and that phosphorus in groundwater was also in siginificant or extremely siginificant negative relationships with Olsen-P,AL-P and Fe-P in the surface soil layer.All the findings indicate that the surface soil layer around the lake is the major source of phosphorous leaching into the lake,and depth of shallow groundwater table the major factor affecting soil phosphorus leaching in the area.

     

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