[Fluorescence Spectral Characteristics of Fluorescent Dissolved Organic Matter (FDOM) in the Surface Sediments from Lihu Lake].

This study investigated the spectral characteristics of fluorescent dissolved organic matter (FDOM) in sediments of Lihu Lake using three-dimensional excitation-emission matrix fluorescence spectroscopy (EEMS),and discussed the correlation between source of FDOM and organic or inorganic nitrogen.The results indicated that the surface sediments in Lihu Lake consisted of three fluorescence fractions (Ⅱ),humic-like C1(240,310/420 nm),C2(260,360/460 nm),and tryptophan-like C3(225,275/340 nm).The total fluorescence intensity ranged from 49.97 to 159.19 R.U.·g-1,and decreased from east to west with higher values in coast district than in lake center.The relative proportions of C1,C2,and C3 were 33.63%,26.87% and 39.49%,respectively.The fluorescence index (FI),biological origin index (BIX),and humification index (HIX) ranged from 1.96 to 2.22,0.69 to 0.94,and 2.62 to 4.39.It indicated that the main source of FDOM in Lihu Lake was from endogenesis,and mainly derived from microbes,algae and other newly autochthonous sources.The results illustrated,the fluorescence intensity had significant correlation with organic and inorganic nitrogen (P<0.01),and had higher correlation with inorganic nitrogen.