School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China; Key Laboratory of Humid Sub-tropical Eco-geographical Process of Ministry of Education of China, Fujian Normal University, Fuzhou 350007, China.
Department of Geography and Resource Management, and Centre for Environmental Policy and Resource Management, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
J Environ Sci (China). 2018 Mar;65:72-82. doi: 10.1016/j.jes.2017.03.024. Epub 2017 Mar 30.
Aquaculture ponds are dominant features of the landscape in the coastal zone of China. Generally, aquaculture ponds are drained during the non-culture period in winter. However, the effects of such drainage on the production and flux of greenhouse gases (GHGs) from aquaculture ponds are largely unknown. In the present study, field-based research was performed to compare the GHG fluxes between one drained pond (DP, with a water depth of 0.05m) and one undrained pond (UDP, with a water depth of 1.16m) during one winter in the Min River estuary of southeast China. Over the entire study period, the mean CO flux in the DP was (0.75±0.12) mmol/(m·hr), which was significantly higher than that in the UDP of (-0.49±0.09) mmol/(m·hr) (p<0.01). This indicates that drainage drastically transforms aquaculture ponds from a net sink to a net source of CO in winter. Mean CH and NO emissions were significantly higher in the DP compared to those in the UDP (CH=(0.66±0.31) vs. (0.07±0.06) mmol/(m·hr) and NO=(19.54±2.08) vs. (0.01±0.04) µmol/(m·hr)) (p<0.01), suggesting that drainage would also significantly enhance CH and NO emissions. Changes in environmental variables (including sediment temperature, pH, salinity, redox status, and water depth) contributed significantly to the enhanced GHG emissions following pond drainage. Furthermore, analysis of the sustained-flux global warming and cooling potentials indicated that the combined global warming potentials of the GHG fluxes were significantly higher in the DP than in the UDP (p<0.01), with values of 739.18 and 26.46mgCO-eq/(m·hr), respectively. Our findings suggested that drainage of aquaculture ponds can increase the emissions of potent GHGs from the coastal zone of China to the atmosphere during winter, further aggravating the problem of global warming.
水产养殖池塘是中国沿海地区的主要景观特征。一般来说，水产养殖池塘在冬季非养殖期会被排水。然而，这种排水对水产养殖池塘温室气体（GHG）的产生和通量的影响在很大程度上是未知的。本研究采用现场研究的方法，比较了中国东南闽江河口冬季一个排水池塘（DP，水深 0.05m）和一个未排水池塘（UDP，水深 1.16m）之间的 GHG 通量。在整个研究期间，DP 的平均 CO 通量为（0.75±0.12）mmol/（m·hr），显著高于 UDP 的平均 CO 通量（-0.49±0.09）mmol/（m·hr）（p<0.01）。这表明排水会使水产养殖池塘在冬季从 CO 的净汇转变为净源。与 UDP 相比，DP 的平均 CH 和 NO 排放量显著更高（CH 为（0.66±0.31）与（0.07±0.06）mmol/（m·hr）和 NO 为（19.54±2.08）与（0.01±0.04）µmol/（m·hr））（p<0.01），表明排水也会显著增强 CH 和 NO 的排放。环境变量（包括沉积物温度、pH 值、盐度、氧化还原状态和水深）的变化对池塘排水后增强的 GHG 排放有重要贡献。此外，持续通量全球增暖和冷却潜势的分析表明，DP 的 GHG 通量综合全球增暖潜势明显高于 UDP（p<0.01），分别为 739.18 和 26.46mgCO-eq/（m·hr）。我们的研究结果表明，冬季水产养殖池塘的排水会增加中国沿海地区向大气排放的强效 GHG，进一步加剧全球变暖问题。
