[Effects of different salinity levels on nitrification processes in sediments of Minjiang River Estuary, China]

Ying Yong Sheng Tai Xue Bao. 2018 Apr;29(4):1313-1320. doi: 10.13287/j.1001-9332.201804.038.
[Article in Chinese]

Abstract

Two estuary wetlands in Minjiang River, Shanyutan and Daoqingzhou, were selected as the research objects. Wetland sediments were collected to examine the effects of different salinity levels on nitrification processes in the wetland with a culture experiment. The results showed that the nitrification rate of sediment in Minjiang River estuary wetland was generally low. The highest nitrification rate of sediment in the Shanyutan wetland was 0.193 mg·kg-1·d-1, while that in the Daoqingzhou wetland did not exceed 0.050 mg·kg-1·d-1. In the low salinity level (5), the decrease of nitrification rate was attributed to the restraint of nitrifying bacteria activities. The nitrification rate slightly increased with the increases of salinity (10), but was still lower than the initial value. This would be owed to the fact that the inhibitory effect of salinity on the activities of aerobic bacteria was strengthened, which reduced the rate of NH4+-N production, and thus resulted in a decrease of the contribution of aerobic ammonification bacteria to the apparent nitrification rate. There were regional variations in the responses of sediment nitrifying activity to salinity. In saltwater wetland (Shanyutan wetland), the adaptability of microbes in sediment to salinity was stronger, so that the nitrification activity in high salinity conditions was still higher. While in the freshwater wetland (Daoqingzhou wetland), the adaptability of the sediment to the salinity change was relatively lower, with a lower nitrification activity of the sediment in high salinity than in middle salinity. Acidic condition was the main reason for the low nitrification in the sediments of Minjiang estuary wetland. The nitrification rate and nitrification activity of the two wetlands increased first and then decreased with the duration of the culture experiment, which was driven by combined effects of initial NH4+-N concentration, oxygen content and denitrifying.

选择闽江河口鳝鱼滩湿地与道庆洲湿地为对象,采集湿地沉积物在室内进行沉积物硝化培养,分析不同盐度水平对湿地沉积物硝化作用的影响.结果表明: 闽江河口湿地沉积物硝化速率普遍较低,鳝鱼滩湿地沉积物最高硝化速率只有0.193 mg·kg-1·d-1,而道庆洲湿地沉积物硝化速率最高不超过0.050 mg·kg-1·d-1.盐度的升高会抑制闽江河口湿地沉积物的硝化作用.低盐度时(5),硝化速率下降的主要原因是硝化细菌活性受到抑制;随着盐度的升高(10),硝化速率略有上升但仍低于初始值,这是由于随着盐度的升高,盐度对好氧氨化细菌活性的抑制程度有所加强,导致系统产生NH4+-N的速率下降,从而造成好氧氨化细菌对表观硝化速率下降的贡献减少.沉积物硝化活性对于盐度的响应存在地域差异.咸水湿地(鳝鱼滩湿地)沉积物中的微生物对盐度的变化适应性较强,从而使该湿地沉积物硝化活性在高盐度条件下仍然较高.淡水湿地(道庆洲湿地)沉积物对盐度变化的适应性较弱,导致其沉积物硝化活性在高盐度条件下低于中等盐度.闽江河口鳝鱼滩与道庆洲的短叶茳芏湿地沉积物硝化作用较低的主要原因是沉积物呈酸性及淹水状态下的缺氧条件弱化了沉积物的硝化作用.两处湿地的硝化速率与硝化活性随时间的变化趋势为先升高后下降,这是由初始NH4+-N浓度、氧气含量和反硝化共同作用造成的.

Keywords: Cyperus tegetiformis; Minjiang River Estuary; nitrification; salinity.

MeSH terms

  • Bacteria, Aerobic
  • China
  • Denitrification
  • Estuaries*
  • Fresh Water
  • Geologic Sediments
  • Nitrification*
  • Rivers
  • Salinity*
  • Wetlands