冬季淹水稻田CH_4排放通量及其δ^(13)C的时间变化特征  

TEMPORAL VARIATION OF CH_4 FLUX AND ITS δ^(13)C FROM WINTER FLOODED RICE FIELD

作　　者：张晓艳[1,2] 张广斌[1,2] 纪洋[1,2] 马静[1] 徐华[1] 蔡祖聪[1] 

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院研究生院,北京100049

出　　处：《土壤学报》2012年第2期296-302,共7页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(40921061;41071169);中国科学院战略性先导科技专项(XDA05020200)资助

摘　　要：通过田间试验研究了持续淹水稻田冬季休闲期和水稻生长期CH4排放通量及其稳定性碳同位组成的时间变化。结果表明:CH4排放在冬季休闲期从4月份呈逐渐上升趋势,至6月份出现排放峰,为CH46.4 mg m-2h-1;水稻移栽后则迅速增加,于7月和8月出现两个排放峰,分别为CH423.1 mg m-2h-1和CH429.8 mg m-2h-1,此后急剧下降,末期稻田排水落干期间出现一个排放峰。冬季休闲期CH4排放总量为CH43.3 g m-2,占全年排放总量的8.9%。稻田排放的δ13CH4在冬季休闲期后期逐渐从-51‰上升至-44‰,然后下降至-56‰。水稻移栽后,δ13C值从-62‰迅速降至-68‰,然后慢慢上升至-60‰,并在较长一段时间内保持不变,后期再次富集13C。末期排水落干对排放δ13CH4影响显著。排放δ13CH4在水稻生长期较冬季休闲期低得多,原因在于冬季休闲期的CH4氧化率很高(60%～90%),而水稻生长期的CH4氧化率相对较低(10%～80%)。全观测期内,CH4排放通量的季节变化均与土壤温度显著正相关(p<0.01),与土壤Eh显著负相关(p<0.01),与δ13CH4呈显著负相关(p<0.05)。Investigations were carried out of CH4 emission and its δ^13C values from a rice field under continuous flooding throughout the fallow and following rice seasons. Results show that in the fallow season CH4 flux rose from April and reached a peak value, about 6.4 mg m- 2 h-1, in June. After rice transplanting, CH4 flux increased quickly at the beginning of the rice season and two peaks occurred in July and August, reaching 23.1 and 29.8 mg m-2 h-1, respective- ly, which was followed by a rapid decrease. Then another peak appeared during the final drainage before rice harvest. The total CH4 emission in the fallow season amounted to 3.3 g m - 2, accounting for 8.9% of the annual total emission. On the other hand, 813 CH4 （emitted）increased gradually from -51%r to -44‰, and then dropped back to -56‰ in the late fallow season. After rice transplanting,δ^13C value decreased from -62‰ to -68‰firstly and then increased swiftly to -60%o, which afterwards remained unchanged for a relatively long time. Late in the season, emitted CH4 became ^13C enriched again. The impact of the final drainage on δ^13CH4 （emitted） was remarkable. Theδ^13C value of emitted CH4 was heavier in the fallow season than in the rice season, because the fraction of CH4 oxidized was higher in the fallow season （60% - 90% ） than during the following rice season （10%- 80% ）. Within the whole observation period, the temporal variation of CH4 flux was positively related to soil temperature （p 〈0. 01 ） , but negatively related to soil Eh （p 〈0.01 ） and to δ^13C value （p 〈0.05） as well.

关 键 词：CH4排放通量 CH4氧化率 稻田 稳定性碳同位素组成 时间变化 

分 类 号：X511[环境科学与工程—环境工程]