艾比湖地区棉田、撂荒地土壤CH_4排放通量日变化规律研究

Research on Soil CH_4 Flux of Cotton Fields and Abandoned Lands in Ebinur Lake Area

【目的】定量分析干旱区农田撂荒前后土壤甲烷(CH4)排放通量的日变化,着重探讨影响土壤CH4排放的环境因子,为解释人类活动对该地区农田生态系统的土壤CH4排放的影响提供数据支持。【方法】用静态箱法结合Li-7700快速CH4分析仪(Li-7700,Li-cor Inc,USA)对艾比湖地区农田生态系统中棉田及撂荒地生长季(2010年8月)的土壤CH4排放浓度和密度进行实时测定,并分析水热因子对土壤CH4排放的影响。【结果】棉田、撂荒地CH4排放具有较明显的昼夜变化,棉田呈双峰曲线,撂荒地呈单峰或双峰曲线。在观测时间内,10 a棉田的平均通量为2.23 mg/(m2.h),最大值为61.01 mg/(m2.h),最小值为-41.05 mg/(m2.h);10 a撂荒地的平均通量为-3.90 mg/(m2.h),最大值为50.25 mg/(m2.h),最小值为-87.39mg/(m2.h)。棉田、撂荒地土壤CH4排放与土壤含水量、空气相对湿度相关不显著;所有样地CH4排放量与15、20 cm的土壤温度相关性最高(相关系数:棉田为-0.70,-0.71;撂荒地为-0.52,-0.52,P<0.01);综合考虑水分、温度因素可以解释土壤CH4排放变化的70.60%～85.61%,这比单独考虑水分或温度对土壤CH4排放变化的解释度都高。【结论】棉田是土壤CH4微弱的源,撂荒地是土壤CH4微弱的汇,水分、温度是影响生长季棉田和撂荒地土壤CH4排放变化最主要的环境因子。

[ Objective] The project aimed to explore the influence of arid zone land use change on the soil CH4 flux and focused on the environmental factors which affected soil CH4 emissions in order to provide data support to explain the impact of human activities in farmland ecosystem soil CH4 emissions of this area. [ Method] The concentration and density of the soil CH4 emissions of the cotton field and abandoned land in Ebinur area were measured by using the static chamber method with Li - 7700 rapid CH4 analyzer （ Li - 7 700, Li -cor, Inc. , USA） in growing season （August, 2010） and the heat and water factors on soil CH4 e- missions were analyzed as well. [ Result ] Cotton fields and abandoned land had obviously diurnal variation dy- namics. Cotton fields showed double peak curve, while abandoned land showed a single peak or double peak curve. During the observation time, the average CH4 flux of 10 a cotton land is 2.23 mg/（ m2·h） , the maxi- mum value is 61.01 mg/（ m2 ·h） and the minimum is -41.05 mg/（m2 ·h） ; the average CH4 flux of 10a abandoned land is -3.90 mg/（m2 ·h）, the maximum value is 50.25 mg/（m2·h） and the minimum is - 87.39 mg/（ m2·h）. There was no significant relationship between soil moisture and soil CH4 emissions. And the air relative humidity was not relevant to soil CH4 emissions, either. The temperature of 15 cm, 20 cm layer in soil had the highest correlation with the diurnal variation for all plots （ cotton fields - 0.70, - 0.71 ; a- bandoned land - 0.52, - 0.52, P 〈 0.01 ） ; Considering the water, the temperature factors can explain 70.60% -85.61% of the soil CH4 emission changes , which surpasses the explanation of separately consider- ing the degree of moisture or temperature changes in the soil CH4 emissions. [ Conclusion] The cotton fields are a weak source of the soil CH4, abandoned lands is in the weak soil CH4 sink, water and temperature are the most important environmental factors which impact soil CH4 emissions change of cotton fields and aban- doned land in the growing season.