The Properties Of Organic Carbon And Organic Nitrogen In Sediments Of The Riparian Areas From Dalian Main Estuaries

A laboratory incubation experiment was conducted to investigate the organic carbon, organic nitrogen, nitrification, denitrification and nitrous oxide emission of the sediments in intertidal belt of rivers by comparing with paddy soils and dry soils nearby. The samples were collected from the riparian areas of Fuhou River, Dasha River, Biliu River and Yingna River in Dalian, Liaoning Province, China. The results as follows:For the intensity of nitrification and denitrification, we still make comparisons in two ways.Compare the intensity of nitrification of the sediments of four rivers: Dasha River > Biliu River > Yingna River > Fuzhou River. The sequence of denitrification was: Dasha River > Yingna River > Fuzhou River > Biliu River. Nitrification-denitrfication intensity of Dasha River was the highest. Compare samples from 3 different functional areas(sediments, paddy soils, dry soils): the nitrification intensity of dry soils was higher than those of sediments or paddy soils, which indicated that the biomass of nitrobacteria in dry soils was relatively high. In the riparian area of Fuzhou River, the sequence of denitrification was: paddy soils > sediments > dry soils, in the riparian area of Yingna River: sediments > paddy soils > dry soils. The results indicated that the nitrification and denitrification depended on the micro-biomass and the basic properties.It was proved that anaerobic ammonia oxidation did react in sediments by measuring the changes of the content of NH4+-N and NO3--N. According to the changes of NH4+-N and NO3--N, it could be indicated that anaerobic ammonia oxidation reacted in Biliu and Yingna river sediments, but did not in Fuzhou River sediments.The process of NO2 production include: nitrification, denitrification, Dissimilatory Nitrate Reduction to Ammonium(DNRA), etc. In laboratory incubation experiment, NO2 was released fast in first 2days, but the rate of release in sediments was relatively lower than that in paddy or dry soils. The results indicated that there were a lot factors to affect the emission of NO2, and some properties in sediments could restrain the emission of NO2. It also could be inferred that the nitrification and denitrification may not be the main processes to release NO2.