Short-term Effects of Nitrogen and Sulfate Addition on CH4 and CO2 Emissions in the Tidal Marsh of Minjiang River Estuary

Abstract

In April 2015, using enclosed static opaque chamber-GC techniques, the short-term effects of nitrogen and sulfate addition on the CH4 and CO2 emissions were measured in the Cyperus malaccensis marsh in the high tidal flat of the Minjiang River estuary, and the key factors controlling the variation of CH4 and CO2 were examined. The influences of nitrogen and sulfate addition on the CH4 and CO2 emissions were different in different time scales. CH4 emission increased significantly under the NH4Cl (NH) and NH4NO3+K2SO4 (NS) additions (P<0.01), CO2emission increased significantly with NS addition (P<0.05), but CH4 and CO2 emissions demonstrated an obvious fluctuation pattern with KNO3 (NO) and K2SO4(S) additions. Compared with the control (CK), average CH4 emissions increased by 286.36% and 122.73%, respectively, in the NH and NS addition treatments, average CO2 emissions increased by 39.92% and 34.24%, respectively, with the NH and NS additions treatments. The nitrogen and sulfate addition changed the temporal variation of CH4 and CO2emissions from the C. malaccensis wetlands in growing season. Significant correlations were found among CO2, CH4 emissions, and soil temperature, electrical conductivity (EC), DOC (dissolved organic carbon) and NH4+-N (P<0.05 or P<0.01) in the treatments with NH and NS additions; and soil temperature, EC, DOC and NO3--N (P<0.05 or P<0.01) in the treatments with NO and NS additions. Temperature, EC and nitrogen availability were the dominant factors controlling the temporal variations of CH4 and CO2emissions in estuarine tidal marsh ecosystem.