滏阳河水系沉积物硝化速率分布及溶解氧的限制效应

Spatial distribution of nitrification rate and the restriction effect of oxygen in the Fuyang River

滏阳河水系低溶氧、高氨氮污染特征突出,本研究通过硝化速率分析,揭示了高度氧亏条件下溶解氧对河流硝化过程的限制效应,并测定了滏阳河水系表层沉积物潜在硝化速率和表面硝化速率.结果发现,滏阳河水系表层沉积物潜在硝化速率在0.001~0.038μmol·h-1·g-1之间,表面硝化速率在3~143μmol·h-1·m-2之间,高值样点均出现在汪洋沟及洨河下游区域,低值样点均出现在汪洋沟上游、邢台牛尾河和滏阳河衡水段.滏阳河水系沉积物潜在硝化速率水平较高,中值高达0.103μmol·h-1·g-1,高于绝大多数文献报道结果;但表面硝化速率处于较低水平,中值仅为38μmol·h-1·m-2,低于大部分文献报道结果.表面硝化速率与潜在硝化速率水平的显著差异表明,滏阳河水系的低氧问题导致沉积物硝化潜力难以充分发挥,沉积物硝化过程受到溶解氧的限制.研究表明,提高水体复氧能力,增加河流溶解氧含量是滏阳河氨氮污染控制的基本对策.

The Fuyang River is characterized by high ammonia and low dissolved oxygen content. This study was intended to reveal the restricting effect of oxygen to nitrification in the highly polluted riverand surface sediment samples were collected in the Fuyang River to measure the potential nitrification rate( PNR) and areal nitrification rate( ANR). Results show that PNR ranged from 0.001 μmol·h-1·g-1to 0. 038 μmol·h-1·g-1and ANR ranged from 3μmol·h-1·m-2to 143 μmol·h-1·m-2. High rate sites appeared both in the lower part of Wangyang Ditch and Xiao River,while low rate sites were in the upper part of Wangyang Ditch,Niuwei River and Hengshui reach of the Fuyang mainstream. PNR in the Fuyang River was high since its median value( 0. 103 μmol·h-1·g-1) was higher than most reported values. However,ANR in the Fuyang River was low because the median value( 38 μmol·h-1·m-2) was lower than most other studies. The distinction between ANR and PNR level indicated that the potential nitrification capacity of the Fuyang River sediment could not be released effectively,which was caused by the low oxygen content in the river. Consequently,enhancing the ability of oxygen reaeration and increasing dissolved oxygen content in the river are basic measures to control the ammonia pollution in the Fuyang River.