Carbon isotopes of water-extractable organic carbon in a depth profile of forest soil imply a dynamic relationship with soil carbon
Carbon isotopes of water-extractable organic carbon in a depth profile of forest soil imply a dynamic relationship with soil carbon
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DOI：
10.1111/j.1365-2389.2012.01465.x
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发表时间：
2012-08-01
影响因子：
4.2
通讯作者：
Hirai, K.
中科院分区：
文献类型：
--
作者：
Nakanishi, T.;Atarashi-Andoh, M.;Hirai, K.
尽管人们对近期凋落物与旧土壤有机质作为森林土壤中溶解有机碳（DOC）来源的重要性进行了大量研究，但有必要对这一机制进行更彻底的评估。我们通过分析 WEOC 的同位素组成（13C 和 14C）及其在 DAX-8 树脂上分离后的组分，研究了冷温带山毛榉林土壤剖面中的水可提取有机碳 (WEOC)。随着深度的增加，WEOC 在 13C 中变得更加富集，这反映了亲水性、同位素较重的部分的比例不断增加。 WEOC 及其组分中的 14C 含量随着深度的增加而降低，与土壤有机质 (SOM) 中的 14C 趋势一致。这些结果表明 WEOC 和土壤有机碳的动态平衡。维持矿质土壤中 WEOC 库的主要过程似乎是微生物从 SOM 中释放水溶性化合物，该过程在数十年到数百年的时间尺度内发生变化。
Although considerable research has been conducted on the importance of recent litter compared with older soil organic matter as sources of dissolved organic carbon (DOC) in forest soils, a more thorough evaluation of this mechanism is necessary. We studied water-extractable organic carbon (WEOC) in a soil profile under a cool-temperate beech forest by analysing the isotopic composition (13C and 14C) of WEOC and its fractions after separation on a DAX-8 resin. With depth, WEOC became more enriched in 13C, which reflects the increasing proportion of the hydrophilic, isotopically heavier fraction. The 14C content in WEOC and its fractions decreased with depth, paralleling the 14C trend in soil organic matter (SOM). These results indicate a dynamic equilibrium of WEOC and soil organic carbon. The dominant process maintaining the WEOC pool in the mineral soil appears to be the microbial release of water-soluble compounds from the SOM, which alters in time-scales of decades to centuries.