摘要
对洱海沉积物间隙水中溶解有机质(DOM)含量、紫外可见吸收、荧光以及分子量等的垂直分布特征进行了研究。结果表明,DOC含量在沉积物水界面明显富集,随后急剧下降,6cm处达到最小值,随后呈上升趋势。DOC与吸光度值、荧光发射光谱强度之间具有一定的线性相关关系。DOM的E3/E4值范围在1～6之间,绝大多数在1～3 5之间。表征DOM中腐殖质来源的指标荧光指数值处于1 48～1 59之间,说明DOM以陆源输入为主。此外,洱海沉积物间隙水DOM分子量分布呈多峰分布模式,重均分子量(Mw)值在1462～1953Da之间,数均分子量(Mn)值在547～900Da之间,多分散性系数ρ值在2 02～3 05之间。随着沉积深度增大,Mw和Mn有略微的增大趋势,但变化不大。沉积物的氧化还原条件、微生物活动以及铁、锰氧化物等在沉积剖面的差异是控制间隙水中DOM各种地球化学特性的主要因素。
We study the DOC concentrations, the UV-Vis absorbance, fluorescence and the molecular weight of the dissolved organic matter in the sediment pore water of Erhai Lake. DOC concentration has a high value at the sediment-water interface, with a sharp decrease within the depth of 6 cm, and, then, increases later. The vertical distributions of α254, α280 and fluorescence intensity at Ex = 335 nm are in agree with the distribution of DOC. The E3/E4 values range from 1 to 6 and most of the values are less than 3.5, which means that the DOM in sediment pore water has relatively high humification, aromaticity and molecular weight. f450/500 values range from 1.48 to 1.59, showing the terrestrial nature of the majority of the sediment pore water DOM. Through the HPSEC results, all the sediment pore water DOM show a multi-modal distribution of the molecular weight. Weight-average molecular weight (Mw), which ranges from 1462 to 1953 Da, and number-average molecular weight (Mn), which ranges from 547 to 900 Da, vary a little along the depth and mainly have a trend of increase. The poly-dispersity, ρ (the ration of Mw to Mn) ranges from 2.02 to 3.05, which suggests that the pore water DOM resides in a relatively wide size distribution. In general, the geochemical characteristics of sediment pore water DOM are attributed to the changes in redox chemistry occurs as a function of the sediment depth, partial mineralization of paniculate organic matter as a result of the biotic or abiotic reduction and the effect of metal oxide through the dissolution and formation process.
出处
《水科学进展》
EI
CAS
CSCD
北大核心
2005年第3期338-344,共7页
Advances in Water Science
基金
国家自然科学基金资助项目(40403011)
国家重点基础研究发展计划(973)资助项目(2002CB412300)
中国科学院知识创新工程重要方向项目(KZCX3 SW 140)~~
关键词
溶解有机质
沉积物间隙水
荧光
高效体积排阻色谱
洱海
地球化学特征
dissolved organic matter
sediment pore water
fluorescence
high-performance size exclusion chromatography
Erhai Lake
geochemical characteristics
