| 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下游水网输送的重要水文通道，也是氮素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，也必然驱动脱氮作用发生变化。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，原位测定计算了过饱和氮气（ΔN2）浓度，采集了各塘表层沉积物用于15N同位素示踪试验，以综合阐明丘陵区典型水塘脱氮效率、机制及其潜势变化特征，并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%）。反硝化作用是各类塘中氮素去除的主导途径，其贡献率高达（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（TN）、溶解性总氮（DTN）浓度是影响林塘、养殖塘脱氮效率的主要因子，化学需氧量（COD）、悬浮固体浓度（TSS）、溶解氧浓度（DO）、叶绿素a（Chl-a）、总磷（TP）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，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 crucial hydrological passages that connect hillslope runoff and nutrient loss with downstream water networks, serving as hotspots for nitrogen (N) removal. However, the characteristics of the overlying water in the ponds are significantly different due to the influence of aquaculture and land use in catchment areas, which inevitably drives changes in denitrification processes. 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. In situ measurements were conducted to calculate the concentration of oversaturated nitrogen gas (ΔN2), and surface sediments from each pond were collected for 15N isotope tracing experiments, in order to comprehensively elucidate the denitrification efficiency, mechanisms, and potential changes in characteristics of typical ponds in the hilly region, 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 (TN) and dissolved total nitrogen (DTN) were the primary factors that influenced the denitrification efficiency in forest ponds and aquaculture ponds. In contrast, the chemical oxygen demand (COD), total suspended solids (TSS), dissolved oxygen (DO), chlorophyll-a (Chl-a), and total phosphorus (TP) 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, targeted environmental condition optimization measures should be taken to enhance their denitrification efficacy, which is of great significance to safeguard the clear water flow in the hilly source area. |
| Key words: ponds denitrification anammox nitrogen removal efficiency |
