富营养化巢湖沉积物溶解性有机质光谱时空分布特征及其环境意义

Spatiotemporal characteristics and its environmental application of dissolved organic matter(DOM)in sediments from Chaohu Lake,a eutrophic lake

通过紫外吸收光谱(UV-vis)和三维荧光光谱(3D-EEMs),研究典型富营养化湖泊巢湖沉积物溶解性有机质(DOM)光谱时空分布特征.结果表明,巢湖表层沉积物DOM的a(254)含量为13.1~101.7 m^-1,平均值为(32.2±16.2) m^-1.其中,夏季沉积物a(254)的含量((46.6±25.6) m^-1)要显著高于其它季节,且湖心区a(254)平均值和变异性均小于湖滨区.表层沉积物DOM的S275~295值从春季到冬季上随时间呈明显上升趋势.沉积物DOM荧光强度在夏季最高,在垂直剖面上总体呈下降趋势.DOM组分以酪氨酸类蛋白质和溶解性微生物产物为主,各组分在空间分布上无明显差异.巢湖沉积物DOM荧光指数(FI)为2.56~4.89,腐殖化指数(HIX)为0.57~6.78,生物源指数(BIX)为0.31~1.54.巢湖沉积物DOM主要来自于生物源,藻的生长循环会显著影响富营养化湖泊沉积物DOM的来源和性质.

Based on ultraviolet⁃visible(UV⁃vis)spectra and three⁃dimensional fluorescence excitation emission matrix spectroscopy(3D⁃EEMs),the spatiotemporal characteristics of dissolved organic matter(DOM)in sediments from Chaohu Lake(a eutrophic lake),were investigated in this study.The results showed that the range of a(254)was 13.1~101.7 m^-1,with the average value of(32.2±16.2)m^-1.The content of a(254)in summer((46.6±25.6)m^-1)was significantly higher than that in other three seasons,while the average content and variability of a(254)in the central lake were lower than those in the littoral area.The values of S275~295 of DOM in surface sediments showed an obvious upward trend from spring to winter.The fluorescence intensity of DOM in sediments was highest in summer,and it was on the decline in vertical profile.The main components of DOM were proteins like tyrosine and soluble microbial by⁃product⁃like,while there was no significant difference in spatial distribution.The ranges of fluorescence index(FI),Humification index(HIX)and biological index(BIX)were 2.56~4.89,0.57~6.78 and 0.31~1.54,respectively.These results indicate that DOM in sediments from Chaohu Lake mainly originated from biological sources.Moreover,the growth cycle of algae has a significant impact on the sources and properties of DOM in the eutrophic lake sediments.