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为准确获取辽河三角洲水稻湿地CH4浓度与通量特征,分析水稻生长发育对CH4浓度与通量的影响,进一步估算稻田CH4排放量,基于采用涡度协方差法(Eddy Covariance Method,EC)获取的2013年4─10月辽河三角洲稻区近地层CH4监测资料,结合水稻生育期,分析了稻田CH4浓度与通量的时间变化规律。结果表明:水稻(Oryza sativa Linn)生长季内,近地层CH4的平均浓度是0.242 mmol·m-3,期间出现3个峰值,分别与泡田期、拔节-抽穗期和成熟期3个生育期相对应;CH4浓度较高时期,其日变化活跃,表现为日间浓度较低夜间浓度较高,日较差大,在其它浓度较低时期,日变化不大。CH4的月排放量在5月最大,为0.700 mol·m-2。CH4通量在水稻生长季内日平均为0.080μmol·m-2·s-1,通量峰值出现规律与浓度一致,其中泡田-移栽期较高,最高值出现在5月11日,为0.707μmol·m-2·s-1,返青期-分蘖期基本无CH4排放,拔节期-抽穗排放量再次升高,之后逐渐降低,在CH4通量较高时期,通量的日变化随气温升高而升高,温度达最大值之后逐渐降低。浓度与通量的日变化呈负相关关系。
In order to obtain accurate CH4 concentration and flux characteristics of rice wetlands in Liaohe Delta, the effects of rice growth and development on CH4 concentration and fluxes were analyzed. CH4 emissions in paddy fields were further estimated. Based on Eddy Covariance Method (EC) According to CH4 monitoring data in the Liaohe River Delta from April to October in 2013, the temporal variation of CH4 concentration and flux in paddy fields was analyzed based on the rice growth period. The results showed that the average concentration of CH4 in the near-surface layer of Oryza sativa Linn was 0.242 mmol · m-3 in the growing season, with three peaks during the growing season, which were respectively compared with those in the soaking stage, the jointing-heading stage and the maturity stage The daily variation of CH4 concentration was high during the high concentration of CH4. The concentration of CH4 was higher at night with lower concentration and the daily difference was higher. At other low concentrations, the daily variation was insignificant. Monthly emissions of CH4 in May the largest, 0.700 mol · m-2. The average daily flux of CH4 flux was 0.080μmol · m-2 · s-1 during the rice growing season. The flux peak was consistent with the concentration of CH4 flux, with the higher soaking-transplanting period and the highest value appeared on May 11, Was 0.707μmol · m-2 · s-1. There was almost no CH4 emission during the turning-green-tillering stage, but the jointing-heading rate increased again and then decreased gradually. During the high CH4 flux, the diurnal changes of flux Temperature rises and rises, the temperature reaches the maximum after the gradual decrease. The concentration and flux of daily change was negatively correlated.