Sediment denitrification rates at six Yangtze River estuary tidal flat locations(mudflats and salt marshes)were measured from July 2003 to October 2004.In winter and summer,spatial distribution of denitrification rates was not great in the Yangtze estuary,while in spring and autumn,denitrification rates had a great spatial distribution because of the human activity effect.The temporal change of denitrification rates was greater.They ranged from 0.2 to 36.4 umolN·m^(-2)·h^(-1),and were higher in the summertime.The annual average of sediment denitrification rate was 18.2±12.3 mu molN · m^(-2)· h^(-1)in the middle tidal flat and 15.1 ±9.45 mu molN·m^(-2)·h^(-1)in the low tidal flat in the Yangtze estuary.Data analysis indicated that the temperature was the primary factor controlling the process of denitrification(significant positive correlation,P<0.01);at the same time,the content of sediment total nitrogen(TN)and the molar ratio of sediment carbon and nitrogen(C/N)had significant positive correlation(P<0.05)and negative correlation(P<0.05)with denitrification rates,respectively.In the Yangtze estuary,increasing of water salinity had no significant inhibition of denitrification because of the wide change range of water salinity.
WANG DongQi1,2, CHEN ZhenLou1, XU ShiYuan1, DA LiangJun1, BI ChunJuan1 & WANG Jun1 1 School of Resources and Environment Science, East China Normal University, Shanghai 200062, China
