Impact of Macrofaunal Activities on the DIN Exchange at the Sediment-Water Interface Along the Tidal Flat of Yangtze River Estuary
大型底栖动物对长江口潮滩沉积物-水界面无机氮交换的影响

The macrofaunal activities exert intensive and extensive influences on the accumulation,transportation,exchange and geochemistry processes of pollutants and redox sensitive elements around the sediment-water interface.Based on the simulated and contrastive analysis method,effects of bivalve Corbicula fluminea activities on dissolved inorganic nitrogen(DIN) exchange between sedimentwater interface in different experimental conditions and nitrogen biogeochemical cycling along the tidal flats of Yangtze River estuary are discussed.In short time experiment,Corbicula fluminea burrowing activities increased NH4+ release from sediments,and NO3- efflux to overlying water was much more in Corbicula fluminea inhabiting core.During long time incubation,NH4+ and NO3- released in turn from the sediments,bioturbation can facilitate NH4+ release from the sediments at the beginning of incubation,and stronger nitrification derived from bioturbation within the sediments enlarge NO3- concentration.Disturbance and bioirrigation of Corbicula fluminea can accelerate organic matter mineralization and NH4+ exchange between overlying water and pore water,result in a larger release from NH4+ pool in top-sediment to overlying water.In conclusion,by means of excretion,burrowing,bioirrigation and bioturbation,Corbicula fluminea activities can evidently modify the nitrogen dynamics in sediment-water system.