Distribution and migration characteristics of nitrogen and phosphorus in sediment-water interface from unstable coal mining subsidence area

Abstract

以淮南后湖非稳沉采煤沉陷区沉积物-水体界面为研究对象,分析该湖未开发区(A区)、水产养殖区(B区)和水生蔬菜种植区(C区)3个功能区上覆水-间隙水-沉积物体系中氮、磷分布及其迁移特征.结果表明,氮、磷在不同水体界面的分布差异较大.其中上覆水中氮、磷浓度表现为A区>B区>C区;间隙水中氮、磷分布差异不显著,然而各功能区间隙水的氮、磷浓度明显高于上覆水,氮、磷主要由间隙水向上覆水中移动;沉积物中氮、磷含量以C区最高.后湖采煤沉陷区水体表现出氮污染、磷限制的现象.;Three water bodies of different functionalities, i.e., undeveloped (A), aquaculture (B), and aquatic vegetable planting (C), in Lake Houhu unstable coal mining subsidence area, were studied to address the distribution and migration of nitrogen and phosphorus in a column system of overlying water column, sediment pore water and sediments. The results showed that the contents of nitrogen and phosphorus were quite different in different sediment-water interface. The concentrations of nitrogen and phosphorus in overlying water column were in the order of A>B>C. Although no significant difference in concentrations of nitrogen and phosphorus in pore waters of these three water bodies were observed, they were distinctly higher than those in overlying water columns. This suggested an upward migration of nitrogen and phosphorus from pore waters to overlying water columns. The highest concentrations of nitrogen and phosphorus were examined in the sediments of aquatic vegetable planting water body. Overall, the study found that water bodies were polluted by nitrogen but had limited availability of phosphorus.