人工林土壤有机碳组分的化学结构特征分析

为揭示人工林土壤有机碳组分的稳定性维持机制,以云南松人工林为研究对象,利用土壤有机碳化学分组方法,结合元素分析和傅里叶变换红外光谱分析等多种研究手段,研究土壤三种稳定有机碳组分化学结构特征的差异.结果表明,云南松人工林地土壤三种有机碳组分(胡敏酸HA、富里酸FA和胡敏素HM)具有相似的化学结构和官能团组成,主要含有酚羟基、少量脂族烃基、羧基、酮型羟基、酰胺基团和少量碳水化合物.但随土壤剖面深度增加,土壤有机碳组分的官能团特征存在差异.剖面深层土壤HA中富含脂肪族基团,至亚表层土壤中HA脂肪族基团含量减少,表层土HA中未显示含有脂肪族基团.研究表明,脂肪族基团与土壤有机碳组分稳定性的维持有密切关系.该结果从官能团结构特征角度为揭示人工林土壤有机碳化学稳定机制提供了科学依据.

The chemical composition and structural features of soil organic carbon (SOC) in plantation

To elucidate the stabilization of soil organic carbon (SOC) in plantation, the chemical composition and structural features of soil organic carbon (SOC) in Pinus yunnanensis plantation were studied, based on chemical fractionation, elemental analysis and FTIR analysis. The results indicated that three organic carbon fractions (HA, FA and HM) in plantation soil has the similar chemical composition and structural features. These three stable carbon fractions consisted mainly of phenolic hydroxyl group, tiny amounts of aliphatic alkyl group, carboxyl group, ketonic type alkyl group, amide group, and small quantities of carbohydrat. The functional groups of soil organic carbon fractions showed increasing trends with increasing soil depth. Specifically, the HA in deeper soils contain a large amount of aliphatic group, but a small amount aliphatic group was found in subsurface soil, and none of these group was found in topsoil. Thus, our results suggest that these susceptible groups is closely related to stabilization of soil organic carbon.