闽江河口短叶茳芏湿地及其围垦的养虾塘CH_4排放通量的比较

Comparison of CH_4 emissions following brackish Cyperus malaccensis marsh conversion to shrimp pond in the Min River estuary

以闽江河口鳝鱼滩的短叶茳芏湿地及由其围垦而成的养虾塘为研究对象,2016年5月—2017年3月,分别采用静态箱-气相色谱法和悬浮箱/静态箱-气相色谱法对短叶茳芏湿地和养虾塘白天CH_4排放通量进行观测,并同步测定短叶茳芏湿地和养虾塘水体/沉积物理化指标.观测期间短叶茳芏湿地和养虾塘均表现为大气中CH_4的排放源,释放量变化范围分别为1.09~38.38 mg·m^(-2)·h^(-1)和0.01~65.38 mg·m^(-2)·h^(-1),均值分别为(11.67±1.99)mg·m^(-2)·h^(-1)和(18.69±4.84)mg·m^(-2)·h^(-1),重复测量方差分析统计结果表明:虽然在整个观测时间尺度上,养虾塘CH_4排放通量与短叶茳芏湿地无显著性差异(p>0.05),但是在养殖期养虾塘CH_4排放通量显著高于同期短叶茳芏湿地(p<0.05),增加了68.0%.短叶茳芏湿地CH_4排放通量与沉积物温度、间隙水总磷含量呈显著正相关关系(p<0.01),养虾塘水-气界面CH_4排放通量与养殖水水深呈显著负相关关系(p<0.01).亚热带河口感潮沼泽湿地围垦成为陆基养虾塘后增加了CH_4排放通量.

Temporal variations of the CH4 fluxes from the Cyperus malaccensis marsh ecosystem and at the water-air and sediment-air interfaces of the shrimp pond converted from C. malaccensis marsh were determined using static chamber and floating/static chamber technique from May 2016 to March 2017 in the Shanyutan wetland of the Min River estuary,Southeast China. The physical and chemical parameters of the water and sediment in the C. malaccensis marsh and the shrimp pond were measured simultaneously. CH4 fluxes from the C. malaccensis marsh and the shrimp pond ranged from 1.09 38.38 mg·m-2·h-1 and from 0.01 65.38 mg·m-2·h-1,respectively,with the average values of（ 11.67±1.99） mg·m-2·h-1 and（ 18. 69 ± 4. 84）mg·m-2·h-1,respectively. Both C. malaccensis marsh and shrimp pond functioned as a source of atmosphere CH4. Using repeated measures ANOVA,although during the whole observation scale,there was no significant difference of CH4 emissions between C. malaccensis marsh and shrimp pond,in theculture period the CH4 emissions from the shrimp pond was significantly higher than that in the C. malaccensis marsh,and increased 68.0%. The CH4 flux from the C.malaccensis marsh demonstrated significantly positive correlation with soil temperature and pore water TP content,and the CH4 flux at the water-air interfaces in the shrimp pond showed significantly negative correlation with water column depth. Our research demonstrates that in the subtropical zone,the coastal marsh ecosystem converted to aquaculture ponds increase CH4 emission.