稻田CO_2、CH_4和N_2O排放及其影响因素

A field study on CO_2, CH_4 and N_2O emissions from rice paddy and impact factors

采用静态箱 (暗箱 ) 气相色谱法对稻田CO2 、CH4 和N2 O排放进行田间原位测量 .植株参与的稻田CO2 排放季节变化与温度的季节变化一致 ,气温 (土温 )是主要驱动因子 ;而土壤水分状况是稻田CH4 、N2 O排放和无植株参与的稻田CO2 排放季节变化的主要驱动因子 .稻田非淹水期N2 O和CO2 排放与土温、气温呈极显著指数正相关 (p <0 0 0 1) ,两气体之间亦呈极显著线性正相关关系 (p <0 0 0 1) .水稻植株自养呼吸和土壤呼吸的温度系数 (Q10 )分别为 2 17和 1 68.稻田CO2 排放与水层深度呈弱的负相关关系 (p <0 0 5) .无植株参与的稻田CO2 、CH4 和N2 O季节平均排放速率分别为 198 3 5± 3 4 0 0mg (m2 ·h) ,0 63±0 2 9mg (m2 ·h)和 169 57± 75 3 0 μg (m2 ·h) ,而在植株参与下 3者季节平均排放速率分别为 113 3 51± 51 16mg (m2 ·h) ,1 3 9± 0 2 0mg (m2 ·h)和 2 3 1 48± 3 5 0 9μg (m2 ·h) .碳收支模拟计算结果表明 。

A field experiment was conducted to evaluate CO_2, CH_4 and N_2O emissions from rice paddy with static-chamber and a modified gas chromatograph (Agilent 4890D). In this paper, gas samples were taken simultaneously from rice-involved and rice-uninvolved plots. The seasonal trend of CO_2 emission from rice-involved plot was determined by air / soil temperature while soil water status was the main factor controlling the seasonal pattern of CO_2 emission from rice-uninvolved plot. Correlation analysis demonstrated that CO_2 emissions were significantly correlated with N_2O fluxes during non-flooding period (p<0.001). The exponential relationships between CO_2 emissions from rice-involved or rice-uninvolved plot and air or soil temperature were expressed through temperature coefficient (Q_(10)), which was for 2.17 and 1.68, respectively (p<0.001). A positive correlation of N_2O flux with soil /air temperature was also obvious during non-flooding period (p<0.001) and a negative correlation of CO_2 emission with water level was perceivable for rice-involved or rice-uninvolved plots (p<0.05). The mean seasonal emission rates of CO_2, CH_4 and N_2O for rice-uninvolved plot were 198.35±34.00mg/(m^2·h), 0.63±0.29mg/(m^2·h) and 169.57±75.30 μg/(m^2·h), respectively. For rice-involved plot, the mean seasonal emission rates of CO_2, CH_4 and N_2O reached 1133.51±51.16mg/(m^2·h), 1.39±0.20mg/(m^2·h),and 231.48±35.09μg/(m^2·h),respectively. The calculation with Q_(10) and mathematic functions suggested that the amount of CO_2 absorbed was more than the released for rice ecosystem over growing season.