盐沼枯落物碳氮和有色溶解有机物淋溶过程研究

The short-term leaching process of salt marsh litters has an important effect on the water quality for Chongming Dongtan Wetland. In this paper, litters of typical salt marsh plants in the Chongming Dongtan Wetland which divided into stems and leaves were collected and inundated in the laboratory for simulating the leaching process in 48 hours. The concentration of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) was measured by total organic carbon analyzer then converted to the amount of cumulative release. UV-visible spectroscopy parameters were the indicator of the concentration of chromophoric dissolved organic matter (CDOM), and change characteristics of fluorescent components in CDOM were determined by fluorescence excitation emission matrix spectra (EMMs) combined with parallel factor (PARAFAC) analysis. Results showed that in the first 48 hours of leaching process, the release process of DOC, TDN, CDOM, two humic-like fluorescent components and two protein-like fluorescent components show a logarithmic curve, which increase rapidly in the first 8 hours but increase slowly or decline slightly from 8 to 48 hours. The differences of initial matrix properties among plants and their parts have a significant effect on the release amount of DOC and TDN from litter. The maximum cumulative release of TDN was positively correlated with the initial organic carbon and nitrogen contents. nitrogen which in litters is more easily lost than organic carbon. The relative amount of each fluorescent component changed little, but there were significant differences among different plant species, which is indicate that the initial leaching of litter is dominated by physical process. Our results show that the leaching of salt marsh litter has a significant impact on the quality of tidal water.