Li Ru-Zhong, Que Feng-Xiang, Xiong Hong-Bin, Wang Li
School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Huan Jing Ke Xue. 2019 Jan 8;40(1):211-218. doi: 10.13227/j.hjkx.201806001.
Sediment and overlying water samples were collected seasonally from five different geomorphic structures (i.e., pools, riffles, gravel bars, point bars, and runs) from two urban reaches of the Shiwulihe River in the Chaohu Lake Basin dominated by high ammonia concentration between July 2017 and March 2018. Both the sediment potential and areal nitrification rates were measured and their seasonal and geomorphological variability were evaluated. The specific differences between every two geomorphic structures were determined using the Mann-Whitney test and the relationship between the overlying water environment or benthic sediments and sediment nitrification was explored based on regression analysis. The results show that:① The studied reaches are seriously polluted by nitrogen and phosphorus and most of the oxidation-reduction potential (ORP) values in the overlying water were are below 0 mV, suggesting strong reducing conditions of the water column. ② The potential nitrification rates (PNRs) across the five geomorphic structures range from 0.002 to 0.079 μmol·(g·h), with a mean value of 0.023 μmol·(g·h). The ranking order of PNRs is pools > point bars > riffles > gravel bars > runs, with a seasonal change pattern of summer > spring > autumn > winter. ③ The areal nitrification rates (ANRs) across the five geomorphic structures range between 0.140 and 13.543 μmol·(m·h), with an average of 3.658 μmol·(m·h). In general, the highest mean value was observed in riffles, followed by runs, and gravel bars and point bars; the smallest value was observed in pools. In addition, ANRs appear to have seasonal change patterns similar to that of the PNRs. ④ According to the difference analysis, there are significant differences between pools or riffles and other features of the PNRs. Extremely significant ANR differences were observed between more than half of the geomorphic structures. ⑤ Regression analysis shows a stronger correlation between sediment nitrification and the overlying water environment, compared with the surface sediment properties.
2017年7月至2018年3月期间，从巢湖流域十五里河两个城市河段的五种不同地貌结构（即潭、浅滩、砾石滩、边滩和河槽）季节性采集沉积物和上覆水样。测量了沉积物潜在硝化速率和面积硝化速率，并评估了它们的季节和地貌变异性。使用曼-惠特尼检验确定每两种地貌结构之间的具体差异，并基于回归分析探讨上覆水环境或底栖沉积物与沉积物硝化作用之间的关系。结果表明：① 研究河段受到氮和磷的严重污染，上覆水中的大多数氧化还原电位（ORP）值低于0 mV，表明水柱处于强还原条件。② 五种地貌结构的潜在硝化速率（PNRs）范围为0.002至0.079 μmol·(g·h)，平均值为0.023 μmol·(g·h)。PNRs的排序为潭＞边滩＞浅滩＞砾石滩＞河槽，季节变化模式为夏季＞春季＞秋季＞冬季。③ 五种地貌结构的面积硝化速率（ANRs）范围在0.140至13.543 μmol·(m·h)之间，平均为3.658 μmol·(m·h)。总体而言，浅滩的平均值最高，其次是河槽、砾石滩和边滩；潭中的值最小。此外，ANRs的季节变化模式与PNRs相似。④ 根据差异分析，潭或浅滩与PNRs的其他特征之间存在显著差异。超过一半的地貌结构之间观察到极显著的ANR差异。⑤ 回归分析表明，与表层沉积物性质相比，沉积物硝化作用与上覆水环境之间的相关性更强。
