Abstract:

The intact soil coreacetylene inhibition technique was used to study the nitrous oxide (N2O) emission and the denitrification performance in the soils,with different land utilization and altitude,from the waterlevelfluctuation zone (WLFZ) in Zhongxian County in the Three Gorges Reservoir Area.The results indicated that the N2O emission and the denitrification rates in the soils of WLFZ varied spatiotemporally.The average N2O emission rate in the soils of cultivated area was 2371±3161 g N/hm2·d,with 3.48 times of artificial vegetation restoration area.The average denitrification rate of cultivated area was 10551±12660 g N/hm2·d,with 539 times of artificial vegetation restoration area,and the difference of denitrification rate was significant (p<005).There was no significant difference in N2O emission and denitrification rates in the soils of different altitude,while the denitrification rate in the soils of low altitude was relatively higher.Analysis indicated that the N2O emission rate in the soils of cultivated area was significantly and positively correlated with soil temperature and Eh(p<005),and its denitrification rate was positively correlated with soil temperature,implying that soil temperature played an important role in regulating N2O emission and denitrification in the soils of WLFZ.The ratio of N2O/(N2O+N2) ranged from 009 to 052 in the study area,suggesting that N2 was the main product of denitrification,but the N2O emission amount cannot be ignored.Land utilization types had a great impact on N2O emission and denitrification in the soils of WLFZ.Human activities,e.g.cultivation,significantly increased N2O emission amount and denitrification loss in the soils of WLFZ