养殖塘CH4通量时空变化特征及其影响因素

本研究基于多通道密闭式动态箱法对亚热带典型养殖塘CH₄通量的时空变化特征及其影响因素进行了分析.结果表明：亚热带养殖塘CH₄主要排放方式是冒泡，CH₄扩散及冒泡通量均呈现明显的季节变化特征.春、夏、秋、冬4个季节CH₄扩散通量分别为：0.113，0.830，0.002，0.005μmol/（m²·s），冒泡通量分别为0.923，1.789，0.006，0.007μmol/（m²·s），冒泡通量占总通量的比例分别为89.04%、68.29%、78.95%和60.52%.在冬、春季养殖塘没有人工管理措施的情况下，CH₄通量随着离岸距离的增加而增大，冬、春季养殖塘中间区域CH₄总通量分别是岸边浅水区的34.70和2.98倍.夏季养殖活跃期CH₄通量在空间上呈现出：人工投食区（7.371μmol/（m²·s））>自然生长区（2.151μmol/（m²·s））>人工增氧区（0.888μmol/（m²·s））>岸边浅水区（0.206μmol/（m²·s））的特征.在0.5h尺度上，春季CH₄扩散通量与水温呈显著正相关关系，与风速呈负相关关系，秋季CH₄扩散通量与水温、风速呈正相关关系，冒泡通量和水温呈正相关关系.在日尺度上，水温是CH₄扩散通量和冒泡通量的主控因子，两者均随着水温升高呈指数增加，并且冒泡通量的水温敏感性Q₁₀（12.72）大于扩散通量（7.78）.

Temporal and spatial characteristics of methane flux and its influencing factors in a typical aquaculture pond

Applied the multi-channel closed dynamic floating chamber, the spatial and temporal variations of CH₄ flux and its impact factors in an aquaculture pond were identified. The results showed that ebullition was the major transport pathway of CH₄ emission. CH₄ diffusion flux and ebullition flux had visible seasonal variation. The CH₄ diffusion flux was 0.113, 0.830, 0.002 and 0.005 μmol/(m²·s) in spring, summer, autumn and winter, respectively. The ebullition flux was 0.923, 1.789, 0.006 and 0.007μmol/(m²·s) in spring, summer, autumn and winter, respectively. The ratio of the ebullition flux to the total flux was 89.04%、68.29%、78.95% and 60.52% respectively in the four seasons. The total CH₄ flux also exhibited spatial variations within the pond. In winter and spring, artificial managements were not performed. The total CH₄ flux increased with increase of offshore distance. The total CH₄ flux was 34.7 and 2.98 times higher in the middle area of the pond than that in the shallow water area close to bank in winter and spring, respectively. But, during breeding period in summer, the spatial pattern of CH₄ flux was related to artificial managements. The total CH₄ flux showed the following sequence: artificial feeding zone (7.371μmol/(m²·s))>natural growth zone (2.151μmol/(m²·s)) >artificial oxygenation zone (0.888μmol/(m²·s)) > shallow water zone along the shore (0.206μmol/(m²·s)). At the half hourly scale, CH₄ diffusion flux positively correlated with water temperature and negatively correlated with wind speed significantly in spring. In autumn, CH₄ diffusion flux positively correlated with water temperature and wind speed.CH₄ ebullition flux positively correlated with water temperature significantly. At the daily scale, water temperature was the main impacting factor of CH₄ diffusion flux and ebullition flux. Both of the fluxes increased exponentially with the increase of water temperature. The water temperature sensitivity(Q₁₀) of ebullition flux was higher than that of diffusive flux. The Q₁₀ was 12.72 and 7.78, respectively.