| 山区小型人工湖CH4排放特征及影响因素 |
| 摘要点击 279 全文点击 6 投稿时间：2025-02-18 修订日期：2025-05-19 |
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| 中文关键词 CH4排放 小型人工湖 利用方式 排放途径 沉积物 时空异质性 |
| 英文关键词 CH4 emissions small artificial lakes utilization patterns emission pathways sediment spatiotemporal variability |
| DOI 10.13227/j.hjkx.202502126 |
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| 中文摘要 |
| 小型湖泊是全球CH4排放的重要来源. 随着人类对水资源需求的不断增强，人为营造或改造形成的小型人工湖泊广泛分布. 但以上小型人工湖的CH4排放动态及其控制机制尚不明确. 研究以重庆主城及周边分布的33个不同功能的小型湖为对象，通过季节性采样和分析，探讨了其CH4浓度和排放通量的时空动态特征及排放途径，评估了沉积物的CH4生产潜力，揭示了人类活动驱使下小型湖泊的功能转变对其水体CH4排放的影响机制. 结果表明，33个人工湖水体CH4浓度变化范围为104~10 234 μmol·L-1，大部分呈现过饱和状态；水-气界面CH4总通量变化范围为-28~14 386 μmol·（m2·d）-1，平均值为（1 469±1 678） μmol·（m2·d）-1，是大气CH4的净排放源；利用方式对小型人工湖CH4通量影响显著，景观型和养殖型湖泊CH4浓度及通量普遍较高，形成了CH4排放热源；灌溉型湖泊略低，饮水型湖泊最低，表现为CH4排放的弱源. 城市发展和养殖活动显著增加了小型人工湖转变为CH4排放热点的风险. 从排放途径看，饮水型湖泊中CH4扩散通量对总通量的贡献率（85%）明显高于灌溉型和养殖型湖泊（69%和61%）；而景观型湖泊中扩散通量贡献率仅为42%，冒泡通量占比达58%，表明利用方式显著改变了小型人工湖CH4排放的主要途径. 此外，沉积物产CH4速率也表现为景观型和养殖型最大，灌溉型次之，饮水型最低，这主要与利用方式导致的湖泊沉积物有机碳含量和微生物活性分异有关. 相关分析显示，水体有机碳与营养盐的积累是导致小型人工湖CH4排放通量差异的关键指示因子；但不同功能湖泊CH4排放通量的关键控制因子存在差异，饮水型和灌溉型湖泊受水体有机碳影响较大，而景观型和养殖型湖泊则主要受营养盐积累的驱动. 研究表明，人类活动导致的水体和沉积物中养分负荷的持续积累提升了小型人工湖CH4排放的风险，且改变了CH4排放的关键驱动因子，在未来的研究中应给与更多的关注. |
| 英文摘要 |
| Small lakes serve as a substantial source of global CH4 emissions. With the growing human demand for water resources， a significant number of small artificial lakes， either created or modified by humans， have emerged and are now widely distributed. However， the dynamics of CH4 emissions and the underlying regulatory mechanisms in these artificial water bodies remain inadequately understood. This study selected 33 small lakes with diverse functions located in the metropolitan area of Chongqing as research subjects， systematically investigating the spatiotemporal dynamics of CH4 concentrations and fluxes， as well as their emission pathways through seasonal sampling and analysis. It further evaluated the CH4 production potential of lake sediments and clarified the impact of changes in utilization patterns， driven by human activities， on CH4 emissions from these small artificial lakes. The results revealed that the CH4 concentrations in the 33 artificial lakes varied from 104 to 10 234 μmol·L-1， with the majority of the lakes exhibiting super-saturation. The total CH4 fluxes ranged from -28 to 14 386 μmol·（m2·d）-1， with an average of （1 469 ± 1 678） μmol·（m2·d）-1， confirming these artificial lakes as net sources of atmospheric CH4. From the perspective of social functions and utilization patterns， landscape and aquaculture lakes typically exhibited much higher CH4 concentrations and fluxes， serving as significant emission hotspots. In contrast， most irrigation lakes located in agricultural landscapes showed moderately lower CH4 concentrations and fluxes. Lakes designated for drinking water supply presented the lowest emissions， acting as minimal CH4 emitters. These findings suggest that the utilization patterns may have significantly influenced CH4 fluxes in these small artificial lakes. Particularly， urban development and aquaculture activities significantly heightened the risk of small artificial lakes evolving into stronger sources of CH4 emissions. From an emission pathway perspective， the CH4 diffusion flux could contribute over 85% to the total flux in drinking-water-type lakes， which was significantly higher than those observed in irrigation-type （69%） and aquaculture-type lakes （61%）. Landscape lakes exhibited a much lower contribution of diffusive flux to the total flux， accounting for only 42%， while bubbling flux constituted 58%. The altered utilization mode substantially modified the primary pathways of CH4 emissions from these small artificial lakes. Furthermore， the rates of CH4 production from sediments were highest in the landscape and aquaculture-type lakes， followed by irrigation lakes， and lowest in drinking-water lakes. These variations can primarily be attributed to differences in organic carbon content and microbial activity within the sediments， which are shaped by distinct utilization patterns. Correlation analysis revealed that the accumulations of organic carbon and nutrients in water were factors determining the variations in CH4 fluxes among different functional types of artificial lakes. However， the predominant controlling factors for CH4 emissions differed across different types of lake. Specifically， in drinking-water-type and irrigation-type lakes， CH4 fluxes were significantly influenced by organic carbon loads， whereas in landscape and aquaculture-type lakes， they were predominantly driven by nutrient accumulation. This study emphasized that continuous nutrient enrichment in waters and sediments， driven by human activities， has significantly increased the risk of CH4 emissions from small artificial lakes and altered the primary controlling factors. Consequently， to accurately evaluate the contribution of small lakes to global greenhouse gas emissions， it is imperative to develop an adaptive prediction model that incorporates patterns of human utilization. |
