丹江口水库表层沉积物有色可溶性有机物空间分布特征及其来源分析

Distribution and source analysis of chromophoric dissolved organic matter in the surface sediments of the Danjiangkou Reservoir

利用三维荧光光谱(Excitation-emission matrices,EEMs)与平行因子分析模型(Parallel factor analysis,PARAFAC)技术研究丹江口水库表层沉积物有色可溶性有机物(Chromophoric dissolved organic matter,CDOM)荧光组分、空间分布特征和来源,以及不同组分荧光强度与其它沉积物指标的相关性.结果表明,丹江口水库37个采样点CDOM由3类5个荧光组分组成,即类蛋白组分C1(285/345 nm)和C2(225,270/335 nm);陆源类腐殖质组分C3(260/450 nm)和C4(360/450 nm)及自生源类腐殖质组分C5(225,310/405 nm).其中代表类蛋白组分的C1和C2占较高比例,占总荧光强度的百分比的平均值为46.37%,C3与C4和C5占总组分的比例平均值分别为34.33%和19.31%.空间分布上3种荧光峰高值都集中在汉江的入湖河口处及丹江库区居民较多的城镇处,且呈现河流大于库区的趋势.荧光指数(FI)、腐殖化指数(HIX)和生物源指数(BIX)都表明丹江口水库沉积物CDOM的来源具有陆源及生物源的双重特征,陆源主要来源于汉江干流和周边城市居民的活动,以及部分区域农业畜禽养殖;生物源主要来自微生物及藻类的降解.相关性分析说明沉积物CDOM与N、P元素的迁移和转化有密切的关系.

Excitation-emission matrix spectroscopy（EEMS） combined with Parallel factor analysis（PARAFAC） was applied to investigate the fluorescent components and characteristics, and its source of chromophoric dissolved organic matter（CDOM） in the Danjiangkou Reservoir. The relationship between the fluorescent intensity of different components and other sediments quality parameter was also investigated. The results indicated that five fluorescent components were identified by PARAFAC, including two protein-like components namely C1（285/345 nm）and C2（225,270/335 nm） and two land -sourced humic-like components namely C3（260/450 nm） and C4（360/450 nm） and one authigenic-source humic-like component namely C5（225,310/405 nm）. The two protein-like components C1 and C2 had high proportion, accounting for 46.37% of the total fluorescence intensity on average, while C3/C4 and C5 accounted for 34.33% and 19.31% respectively. Spatially, three fluorescence peak values were observed in the Hanjiang region and Danjiang urban region, and showed a tendency of river beging higher than the reservoir area.Fluorescence index（FI）, biogenic index（BIX） and humification index（HIX） showed that CDOM in the surface sediments was derived from both land -sourced materials and endogenous sources, and the former originated primarily from Hanjiang river and the activities of urban residents, as well as the regional agriculture livestock and poultry breeding. Endogenous sources mainly from the degradation of microorganism and algae.Correlation analysis showed that CDOM in the surface sediments and the migration and transformation of N and P has a close relationship.