| 摘要: |
| 丘陵区水塘主要分布在低洼的沟谷区域，多由坡面产流汇集而成，是承接坡地径流及养分流失，并输送至下游水网的重要水文通道，也是发生脱氮作用的热区。然而，受水产养殖及集水坡地土地利用的影响，水塘中上覆水特征差异显著，也必然驱动脱氮机制、潜势及其效率的变化。本研究选择太湖上游丘陵区4类典型水塘（茶园塘、林塘、养殖塘和村塘）为研究对象，采集各塘表层沉积物用于15N同位素示踪试验，并原位测定计算过饱和氮气（ΔN2）浓度，以综合阐明丘陵区典型水塘脱氮机制、潜势及其效率变化特征，同步解析驱动丘陵区不同类型沟塘脱氮效率变化的主要因子。结果表明，茶园塘脱氮效率（8.25%）最高，其次是林塘（6.24%）、村塘（5.90%），而养殖塘脱氮效率最低（4.72%）。反硝化作用是各类型水塘中氮素去除的主导途径，贡献率高达93.34%±12.59%，林塘和茶园塘厌氧氨氧化脱氮贡献率相对高，达到5%以上。相关性分析结果表明，水塘脱氮效率与上覆水理化性质有关，但不同类型水塘之间控制因素存在差异，总氮、溶解性总氮浓度是影响林塘、养殖塘脱氮效率的主要因子，化学需氧量、悬浮固体浓度、溶解氧浓度、叶绿素a、总磷是影响林塘脱氮效率的主要因子，而茶园塘并未识别出影响脱氮效率的主导因子。对于不同类型水塘，管理者应采取针对环境条件的优化措施以提升其脱氮效能 ，这对于保障丘陵源头区清水产流具有重要意义。 |
| 关键词: 水塘湿地 反硝化 厌氧氨氧化 脱氮效率 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Nitrogen removal efficiency and driving factors in typical ponds from a hilly region in the upper Taihu lake basin |
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Liu Caijie1, Lin Xiaoying1, Zhang Wangshou2, Wang Huiliang1, Zhao Xiaofan1, Li Hengpeng2
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1.: School of Water Conservancy and Transportation,Zhengzhou University;2.: Key Laboratory of Watershed Geographic Science,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences
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| Abstract: |
| Ponds in hilly areas are predominantly located in low-lying valleys, often formed by the convergence of runoff from hillslopes. These ponds are to undertake the slope runoff and nutrient loss, and transported to the downstream water network of the important hydrological channel, but also serving as hotspots for nitrogen (N) removal. However, aquaculture and land use activities in the hillslopes or within ponds significantly affect their overlying water characteristics, subsequently driving changes in denitrification mechanisms, potential, and efficiency. This study examines four types of typical ponds in the hilly area of the upper Taihu Lake: tea ponds, forested ponds, aquaculture ponds, and village ponds. Surface sediments from these ponds were collected for 15N isotope experiments. In-situ measurements were carried out to calculate the supersaturated nitrogen (ΔN2) concentrations, and the physicochemical properties of the overlying water were also determined to comprehensively elucidate the characteristics of N removal mechanisms, potential, and efficiency variations, and to analyze the driving factors of denitrification efficiency in different types of ponds. Results indicated that the denitrification efficiency of the tea pond was the highest (8.25%), followed by the forest pond (6.24%) and the village pond (5.90%), while the aquaculture pond exhibited the lowest (4.72%). Denitrification was the dominant N removal pathway in all pond types, with a contribution rate of 93.34%±12.59%. In contrast, anaerobic ammonium oxidationin forest ponds and tea ponds contributed a relatively high percentage of nitrogen removal, reaching more than 5%. Correlation analysis revealed that the efficiency of nitrogen removal in ponds was related to the physicochemical properties of sediments and overlying water, with differing controlling factors among pond types. Specifically, the concentrations of total nitrogen and dissolved total nitrogen were the primary factors that influenced the denitrification efficiency in forest ponds and aquaculture ponds. In contrast, the chemical oxygen demand, total suspended solids, dissolved oxygen, chlorophyll-a, and total phosphorus were identified as the main factors affecting the denitrification efficiency in village ponds. For tea ponds, no significant factors impacting denitrification efficiency were identified. For different types of ponds, managers should take measures to optimise the environmental conditions to enhance the effectiveness of nitrogen removal, which is of great significance to safeguard the clear water flow in the hilly source area. |
| Key words: ponds denitrification anammox nitrogen removal efficiency |
