富营养化湖泊夏季表层水体温室气体浓度及其影响因素

In order to study the concentrations of greenhouse gases in eutrophic lake water and their influencing factors, taking the west bank of Taihu Lake and Zhushan Bay as examples, a total of 27 sites were investigated. The headspace equilibrium method was used to determine the concentrations of dissolved methane (CH4) and nitrous oxide (N2O) in the surface water. The results showed that the concentrations of the two greenhouse gases CH4 and N2O in the surface water of the cyanobacterial bloom accumulation area in the nearshore zone of Taihu Lake were much higher than those in the open lake area sites. The maximum concentrations of CH4 and N2O were 3.79 ± 0.095 and 0.078 ± 0.003 μmol/L respectively. The average concentrations of CH4 in the cyanobacterial bloom accumulation area and the open lake area were 2.33 ± 1.46 and 0.14 ± 0.059 μmol/L respectively, and the average concentrations of N2O were 0.054 ± 0.024 and 0.023 ± 0.012 μmol/L respectively. Both gases were supersaturated in water, and the saturations of CH4 and N2O in the surface water of the cyanobacterial bloom accumulation area were much higher than those in the open lake area sites. In addition, the concentration of dissolved N2O in the surface water of the estuary area of the inflowing river was relatively high. The correlation analysis between the concentrations of CH4 and N2O in water and the water environmental factors showed that the concentrations of total nitrogen, total phosphorus, ammonium nitrogen and dissolved organic carbon in water were significantly positively correlated with the concentrations of CH4 and N2O, and the concentration of CH4 was significantly negatively correlated with the concentration of nitrate nitrogen. The research results revealed that the cyanobacterial bloom accumulation area in Taihu Lake is an important potential emission source of the two greenhouse gases CH4 and N2O, and the outbreak of cyanobacterial bloom has an important impact on the emission of greenhouse gases in the lake. However, the driving mechanism and influencing factors of this process still need to be further studied.

为研究富营养化湖泊水体温室气体浓度及其影响因素,以太湖西岸和竺山湾为例,共调查研究了27个点位,采用顶空平衡法对其表层水体中溶解的甲烷（CH4）和氧化亚氮（N2O）浓度进行测定.结果表明,太湖近岸带蓝藻水华堆积区表层水体中CH4和N2O两种温室气体浓度远远高于开阔湖区点位,CH4和N2O最高浓度分别为3.79±0.095和0.078±0.003μmol/L.蓝藻水华堆积区和开阔湖区CH4平均浓度分别为2.33±1.46和0.14±0.059μmol/L,N2O的平均浓度分别为0.054±0.024和0.023±0.012μmol/L.两种气体在水中均呈现过饱和状态,其中蓝藻水华堆积区表层水体中CH4和N2O饱和度远远高于开阔湖区点位.此外,入湖河流河口区域表层水体溶解性N2O浓度较高.将水中CH4和N2O浓度与水体环境因子之间进行相关性分析,表明水体总氮、总磷、铵态氮和溶解性有机碳浓度与CH4和N2O浓度呈显著正相关,CH4浓度与硝态氮浓度呈显著负相关.研究结果揭示了太湖蓝藻水华堆积区是CH4和N2O两种温室气体重要的潜在排放源,蓝藻水华暴发对湖泊温室气体的排放具有重要影响,但该过程的驱动机制及影响因素仍需要进一步研究.