Long-term dynamics of soil organic carbon and effect of temperature increase on the residence time of soil organic carbon

1.土壤有机碳结构特征与~ 1C年龄的关系为了<14>阐明土壤有机碳的长期动态，分析了~ 1C<14>年龄与土壤腐殖化程度、~ 1C CPMAS NMR谱估计的碳官能团组成<13>、氧化钌氧化降解释放的多核芳香族组分组成以及<13>土壤腐殖酸的δ^ C之间的关系。从两种棕色森林土壤稻生（丰田，爱知）和宫崎（宫崎，宫崎）的A2或A3层中获得胡敏酸，并通过用丙酮-0.01 M NaOH分级沉淀将其分级成7或8个级分。在每种土壤中，^<14>C年龄与两个指示腐殖化程度的变量之间存在显著相关性。随着腐<14>殖化程度和碳龄的增加，腐殖酸碳以烷基碳和芳香碳形式存在的比例分别减少和增加。RTO产物的气相色谱分析 关于我们 cts表明，随着碳龄的增加，多核芳香结构的含量和缩合度增加<14>。另一方面，两种土壤的腐殖化程度随时间的增加速率不同：稻叶土壤的整个腐殖化过程为2800年，而宫崎土壤的腐殖化过程为190年。然而，与以前的结果相比，稻生的结果是一个特殊的情况下，温度条件的差异并不影响腐殖酸的结构变化率。通过酸水解去除腐殖酸和肽，<14>腐殖酸组分的^ C年龄仅改变了30年。因此，这些组分在腐殖化的初始阶段就已被纳入腐殖酸结构中，并一直保存下来.温度升高对土壤有机碳停留时间的影响为了了解全球预警对不同腐殖化阶段土壤有机碳停留时间的影响，以稻生棕色森林土壤A1层为研究对象，在15、20、25、30、34、37和40℃下培养。在40、120、260和365天后收集土壤，测定全C和胡敏酸C含量以及胡敏酸的腐殖化程度。腐殖酸的组成相对于腐殖化的程度的变化也进行了研究，使用部分沉淀与丙酮-0.01 M NaOH。土壤全碳在30℃以下的下降幅度大于在30℃以下的下降幅度。而365天后的胡敏酸含量在7个处理间差异不显著。分级沉淀显示在具有较小程度的加湿的级分中没有减少。因此，温度从15 ℃升高到40℃并不影响腐殖物质在一年内的停留时间。少

1. Relationship between structural properties and ^<14>C age of soil organic carbonTo elucidate the long-term dynamics of soil organic carbon, relationships between ^<14>C age and degree of humification, composition of C functional groups as estimated by ^<13>C CPMAS NMR spectra, composition of polynuclear aromatic components released on oxidative degradation with ruthenium oxide oxidation (RTO), and δ^<13>C of humic acids in a soil layer were analyzed. Humic acids were obtained from the A2 or A3 horizon of two brown forest soils, Inabu (Toyota, Aichi) and Miyazaki (Miyazaki, Miyazaki), and fractionated by fractional precipitation with acetone-0.01 M NaOH into seven or eight fractions. In each soil, there were significant correlations between ^<14>C age and two variables indicating degree of humification. With increasing ^<14>C age and degree of humification, the proportion of humic acid C present as alkyl C and aromatic C decreased and increased, respectively. GC analysis of RTO produ … More cts showed the increases in the content and degree of condensation of polynuclear aromatic structures with increasing ^<14>C age. On the other hand, the rate of increase in the degree of humification with time differed between the two soils: 2800 years for whole humification process in Inabu while 190 years in Miyazaki. Nevertheless comparison with the previous results suggested that the Inabu result is a specific case and the difference in temperature conditions does not affect the rate of structural changes of humic acids. Removal of saccharides and peptides by acid hydrolysis changed ^<14>C age of humic acid fractions only by 30 years. Therefore, such components were incorporated in the humic acid structure during the initial stage of humification and have been survived.2. Effect ofincrease in temperature on the residence time of soil organic carbonTo understand the influence of global warning on the residence time of soil organic carbon at different stage of humification, the A1 horizon of Inabu brown forest soil was incubated at 15, 20, 25, 30, 34, 37, and 40℃. Soil was collected after 40, 120, 260, and 365 days, and total C and humic acid C content as well as the degree of humification of humic acid were determined. Change in the composition of humic acids with respect to the degree of humification was also examined using factional precipitation with acetone-0.01 M NaOH. Total C in soil decreased with a larger extent at temperatures of〓30℃ than at less than 30℃. However, humic acid contents after 365 days did not differ significantly among the seven treatments. Fractional precipitation showed no decrease in the fractions with smaller degree of humificatioan. Thus, the increase in temperature from 15 to 40℃ did not influence the residence time ofhumic substances within a year. Less