冬季大黑汀水库沉积物-水界面氮磷赋存特征及交换通量

本文研究了大黑汀水库表层沉积物碳氮磷污染负荷及分布特征，利用Peeper （pore water equilibriums）技术获取沉积物-水界面氮磷剖面特征，分析大黑汀水库间隙水氮磷分布的空间差异；采集沉积物无扰动柱样用静态培养法对其水土界面氮磷交换速率进行估算.结果表明：沉积物中TN、TP和TOC的含量分别在729~5894mg/kg、1312~2439mg/kg和0.5%~5.6%之间，沉积物中氨氮（NH₄⁺-N）、硝酸盐氮（NO₃^--N）、亚硝酸盐氮（NO₂^--N）和活性磷（PO₄^3--P）含量分别在0.6~202.9、34.4~168.3、0.1~0.3和16.1~75.2mg/kg之间，主要表现为下游含量高于上游，空间分布特征明显；沉积物C/N表明该水库有机质主要来源于水体内部，与人类网箱养殖活动有关.间隙水中NH₄⁺-N和PO₄^3--P浓度远高于上覆水，表明大黑汀水库间隙水具有向上覆水体扩散营养盐的潜力.在垂直方向上间隙水中NH₄⁺-N浓度随深度的增加而变大，PO₄^3--P浓度具有在0~4cm快速增加，之后表现出逐渐降低的趋势.静态释放结果表明，沉积物-水界面NH₄⁺-N和PO₄^3--P的交换通量分别为3.5~110.5mg/（m²·d）和0.1~1.6mg/（m²·d），NO₃^--N和NO₂^--N交换通量在-112.5~157.2mg/（m²·d）和0.04~0.94mg/（m²·d）之间.NH₄⁺-N、NO₃^--N和PO₄^3--P在下游表现出较高的释放速率.较高的沉积物内源负荷使得大黑汀水库沉积物具有较大的向上覆水释放营养盐的潜力，改善水库沉积物污染状况是治理大黑汀水库水体环境的必要之举.

Distribution characteristics and exchange flux of nitrogen and phosphorus at thesediment-water interface of Daheiting Reservoir in winter

In this paper, the pollution load and distribution characteristics of carbon, nitrogen and phosphorus in surface sediments of Daheiting Reservoir were studied. The characteristics of nitrogen and phosphorus profiles at the sediment-water interface were obtained by pore water equilibriums technology, and the spatial differences of NH₄⁺-N and PO₄^3－-P in the interstitial water of Daheiting Reservoir were analyzed. The results showed that the contents of TN, TP and TOC in sediments were 729~5894mg/kg, 1312~2439mg/kg and 0.5%~5.6%, respectively. The contents of NH₄⁺-N, NO₃^－-N, NO₂^－-N and PO₄^3－-P in sediments were 0.6~202.9, 34.4~168.3, 0.1~0.3 and 16.1~75.2mg/kg, respectively, and the spatial distribution was significantly different. Sediment C/N ratio indicated that the substances inwater were the source of organic matter because of human cage culture activities. The concentration of NH₄⁺-N and PO₄^3－-P in the interstitial water was much higher than that in the overlying water, indicated that nutrients have the potential to diffuse from interstitial water to overlying water. In the vertical direction, the concentration of NH₄⁺-N in interstitial water increases with depth, and PO₄^3－-P increases rapidly at 0~4cm, then decreases gradually. The exchange fluxes of NH₄⁺-N and PO₄^3－-P across the sediment-water interface were 3.5~110.5mg/(m²·d) and 0.1~1.6mg/(m²·d), respectively. The exchange fluxes of NO₃^－-N and NO₂^－-N were -112.5~157.2mg/(m²·d) and 0.04~0.94mg/(m²·d), respectively. NH₄⁺-N, NO₃^－-N and PO₄^3－-P showed higher exchange fluxes downstream. Higher sediment endogenous load made the sediments of Daheiting Reservoir have greater potential to release nutrients to overlying water,so controlling the pollution state of sediment is a necessary measure to manage the water environment of Daheiting Reservoir.