东海表层沉积物中中性糖的赋存特征及其在有机质降解中的指示

摘要

Neutral sugars (NS) are abundant constituents of organic matter in sediments.Composition and distribution are meaningful for understanding the origination and degradation in biogeochemical processes.We detected the total organic matter (TOC) and NS in the surface sediments samples collected in the East China Sea in 2009 and 2010,and studied the NS abundance,composition,and origination,and discussed its implication to the degradation states of organic matter.It is shown that the TOC in the sediments ranged from 66.8 to 1441.7 in average of (409.4±55.2)μmol/g,the NS ranged 0.40 to 4.87 in average of (3.07±0.31)μmol/g,while the neutral sugars mol％ C yields of TOC ranged 1.88％ to 8.93％.Generally,with the grain sizes of sediments increasing,the contents of TOC and NS decreased and the Mole yield of glucose (Glc) increased,while the Mole yield of galactose (Gla),mannose (Man) and xylose (Xyl) decreased,indicating that the degradation degree become obvious.Moreover,we found that the ratio of mol％ (Glc+Fuc)/mol％ (Gal+Ara) could indicate the degradation state of organic matter.The degradation degree of organic matter increased with the decrease of the ratio of mol％ (Glc+Fuc)/mol％ (Gal+Ara).%中性糖作为有机质的重要组分,其丰度和组成对于沉积物中有机质的来源和降解等生物地球化学过程具有重要的指示意义.本文在对2009年和2010年采集自东海的24个表层沉积物中有机质和中性糖组成以及分布特征进行分析的基础上,探讨了中性糖及其组分在指示东海表层沉积物有机质来源和降解程度中的作用.结果表明:东海表层沉积物中有机碳(TOC)和中性糖(NS)含量较高,分别为66.8-1441.7μmol/g和0.40-4.87μ mol/g,平均浓度分别为(409.4±55.2)μmol/g和(3.07±0.31)μmol/g,NS占有机碳的碳摩尔百分数为1.88％-8.93％;随着沉积物粒径增大,TOC、NS含量降低,NS中的葡萄糖组分摩尔百分数增大,而半乳糖、甘露糖和木糖组分摩尔百分比减小,表明沉积物中有机质降解程度增大.同时发现,葡萄糖和海藻糖的摩尔分数之和与半乳糖和阿拉伯糖的摩尔分数之和的比值可作为判断沉积有机物降解程度的指标,其值越大,说明沉积有机物的生物降解程度越小.