广东省不同水库底泥理化性质对内源氮磷释放影响

Release of nitrogen and phosphorus from the sediments of ten reservoirs in Guangdong province

采用分级浸取分离方法,分析了广东省10个典型水库底泥的氮磷营养形态分布和污染状况;并通过模拟覆水试验,研究了不同水库底泥氮磷形态及理化性质对内源氮磷释放的影响。结果表明：广东省10个水库底泥氮磷污染较为严重,全氮含量为0.33~3.31 g.kg^-1,平均值为1.70 g.kg^-1;全磷含量为0.14~2.63 g.kg^-1,平均值为1.31 g.kg^-1。底泥氮磷主要以可转化态形式存在,可转化态氮磷含量占总氮磷含量百分比分别为41.2%~71.4%和53.6%~93.2%。底泥内源氮磷的释放主要受氮磷的赋存形态和含量的影响,水库底泥总氮的释放量与离子交换态氮（IEF-N）、碳酸盐结合态氮（WAEF-N）、铁锰氧化物结合态氮（SAEF-N）呈极显著正相关关系,相关系数分别为0.931、0.814、0.807;总磷的释放量与碳酸盐结合态磷（WAEF-P）、铁锰氧化物结合态磷（SAEF-P）呈极显著正相关,相关系数分别为0.960、0.957;这几种氮磷形态是上覆水体中氮磷的重要来源。同时底泥内源氮磷释放还与底泥机械组成有关,其中总氮和总磷释放量与底泥黏粒质量分数呈显著正相关,相关系数分别为0.738、0.638;而总氮的释放量与底泥砂粒质量分数呈显著负相关,相关系数为-0.685。这可能与可转化态氮磷更多的分布在细粒级底泥中有关,细颗粒底泥氮磷释放是上覆水体氮磷的主要来源。

Sequential extraction was used to study concentrations and forms of nitrogen and phosphorus in sediments collected at ten reservoirs in Guangdong province.Release of nitrogen and phosphorus as well as their relation with sediment properties were also investigated using simulation experiments.The results showed that the sediments of ten reservoirs were heavily contaminated with nitrogen and phosphorus.The total nitrogen concentrations in sediments ranged from 0.33 to 3.31 g.kg^-1 with an average of 1.70 g.kg^-1,and the total phosphorus concentrations were in the range of 0.14-2.63 g.kg^-1 with an averaged of 1.31 g.kg^-1.The main forms of nitrogen and phosphorus were transferable,and their percentages in total nitrogen and phosphorus accounted for 41.2%-71.4% and 53.6%-93.2%,respectively.The release of internal nitrogen and phosphorus from sediment was mainly affected by their forms and concentrations.There was a significantly positive correlation between nitrogen release with its concentrations of ion-exchangeable（IEF-N）,carbonate bound（WAEF-N） or iron-manganese oxides bound form（SAEF-N）.Similarly,there was a significantly positive correlation between phosphorus release with its concentrations of carbonate bound（WAEF-P） or iron-manganese oxides bound form（SAEF-P）.These forms of nitrogen or phosphorus were the main source of water eutrophication.The release of internal nitrogen and phosphorus from sediment was also affected by the particle size of the sediments.The release of nitrogen and phosphorus was significantly positively correlated with sediment clay proportion.It was suggested that the fine-grained sediment was possibility the main source of nitrogen and phosphorus release to the overlying water.