水稻土和湿地土壤有机碳测定的CNS元素分析仪法与湿消化容量法之比较

Comparison Between CNS Element Analyzer Method and Wet Digestion Volumetric Method to Determination of Organic Carbon in Wetland Soils and Paddy Soils

摘要:

土壤固碳研究中需要精确的（有机）C计量，而常规的湿氧化法与 CNS 元素分析仪法测定结果的吻合性是C计量中的问题。国外对旱地土壤的研究表明，这两种方法的结果基本可以对比，但是否同样对于湿地土壤也适用还不清楚。采用 CNS 元素分析仪（仪器法）和重铬酸钾外加热湿氧化法（容量法）对 20 个水稻土样品，26 个淡水湿地土壤样品和 20 个沿海湿地土壤样品进行了总有机C (TOC) 的对比测定。结果表明，无论是土壤的表土样品还是剖面样品，仪器法测定结果约低于容量法 10% 以下。两种方法对淡水湿地土壤和水稻土的有机C含量的测定可以对比，但是重铬酸钾氧化容量法对于含氯化物较高的沿海湿地土壤有机C的测定可能不精确。CNS 元素分析仪测定的精密度和准确度较高，可以用于各种湿地土壤的C计量。

Abstract:

Reliable C counting is necessary for the sequestration of soil organic carbon(SOC）, however there is always some discrepancy between the measured results obtained with the wet digestion method and with the CNS elemental analyzer. While comparable results with the two methods were reported for dry croplands, it is unknown whether comparable results for wetland soils can be got with these two methods. Thus, a comparative determination of SOC with the two methods was conducted on 20 samples of paddy soils, 26 of fresh marsh soils and 20 of coastal tidal soils. It showed that SOC contents of both the topsoil and profile samples measured with the CNS analyzer were 10% lower than those of the wet digestion method. Comparable results for paddy soils and fresh marsh soils can be got with the two methods, but unreliable results may be got for coastal tidal soils with the wet digestion one. The CNS Analyzer could measure all kinds of wetland soils’ C due to the high accuracy and precision.