南极南设得兰群岛附近海域表层沉积物中有色溶解有机物的分布特征及来源分析

在南极南设得兰群岛附近海域采集了6个表层沉积物样品,测定了提取液中溶解有机物(DOM)的有机碳含量、紫外-可见吸收光谱和三维荧光光谱,并对有色溶解有机物(CDOM)的分子量信息及各荧光组分的成分和来源进行了分析。结果表明,南设得兰群岛附近海域表层沉积物中DOM提取液的溶解有机碳(DOC)及沉积物有机碳(SOC)的含量呈现由近岸向开阔海域递减的趋势,紫外-可见吸收光谱中的吸收系数(a)也表现出了相似的性质,光谱斜率比(SR)表明近岸沉积物CDOM老化程度较强。通过对三维荧光光谱的分析可知,南设得兰群岛附近海域表层沉积物中的CDOM包含3种荧光组分,即类色氨酸、海洋类腐殖质和陆源类腐殖质,表现出较强的自生源特征,整个研究海域CDOM来源以内源为主,受陆生植物和土壤有机质的外源输入影响较小。通过CDOM各参数的相关性分析发现,沉积物DOM提取液的DOC含量与SOC含量以及吸收系数和腐殖化指数(HIX)等参数相互之间都呈显著正相关,相关系数(r)均在0.88以上,显著性水平P0.01。

Distribution and Source of Chromophoric Dissolved Organic Matter in Surface Sediments from the Sea Area Surrounding the South Shetland Islands,Antarctica

Six surface sediment samples were collected from the sea area surrounding the South Shetland Islands in Antarctica. The UV-Visible absorption spectrum and three-dimensional fluorescence spectroscopy of the chromophoric dissolved organic matter (CDOM) in the sediment extraction liquid were analyzed. Moreover, the molecular weights, fluorescence components, and sources of the DOM were discussed. The results showed that the contents of DOC and sediment OC, values of the absorption coefficients (a), and aging degree of the spectral slope ratio (S_R) of the inshore samples were higher than the offshore samples. The three-dimensional fluorescence spectroscopy for all sampling sites indicated that CDOM in the extraction liquid comprised three fluorescent components: tryptophan-like, marine humic-like, and terrestrial humic-like material. The humic-like components of CDOM were derived mainly from autochthonous sources. Significant linear relationships between the contents of DOC, contents of sediment OC, values of the absorption coefficients (a₂₈₀, a₃₅₅ and a₄₄₀), and HIX were observed, for which the correlation coefficients (r) were all >0.88 (P < 0.01).