Organic matter stabilization in young calcareous soils as revealed by density fractionation and analysis of lignin-derived constituents
Organic matter stabilization in young calcareous soils as revealed by density fractionation and analysis of lignin-derived constituents
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DOI：
10.1016/j.orggeochem.2006.05.002
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发表时间：
2006-01-01
影响因子：
3
通讯作者：
Guggenberger, Georg
中科院分区：
文献类型：
--
作者：
Gruenewald, Gritta;Kaiser, Klaus;Guggenberger, Georg
研究了富钙碱性土壤（石灰性土壤）中有机质（OM）的稳定化机理及其可能的有机-无机相互作用。我们采样的土壤，开发了一段70年的自然演替下，从均匀的石灰质和有机物的基质，从工业生产。我们利用了从非木本木本被子植物植被随着土壤年龄的增加和跟踪木质素作为植物残留物的命运的指标的转变。采用密度分离和超声波分散相结合的方法，可获得4个有机质组分：（1）游离颗粒有机质（FPOM），（2）土壤团聚体中的有机质（OPOM），（3）密度为1.6-2.2 g cm（-3）的重质组分和（4）密度> 2.2 g cm（-3）的重质组分。馏分进行了分析的C，N，CuO氧化产物和矿物成分。团聚体中有机质的积累对土壤总有机碳的贡献很小（4-16%）。有机碳主要分布在> 1.6 g cm ~（-3）的组分中。> 1.6 g cm（-3）级分中的木质素酚表现出最强烈的成岩作用，这反映在香草、肉桂和肉桂（VSC）木质素的产率较低以及香草酚侧链的较强氧化。与POM组分相反，来自较老地点的> 1.6 g cm（-3）的组分保留了以前植被的非木本被子植物木质素特征，表明OM周转较慢。两种重馏分的矿物组成明显不同，层状双氢氧化物（即，水滑石和水铝钙石）占> 1.6 g cm（-3）的级分，方解石占> 2.2 g cm（-3）的级分。我们得出结论，部分降解木质素，富含酸性基团，积累在馏分1.62.2克cm-（3），由于优先吸附带正电的层状双氢氧化物。虽然只代表一小部分的土壤矿物组合，层状双氢氧化物似乎是OM积累的显着相关性。多年来，1.6-2.2 g cm（-3）组成了最大的有机碳库。与1.6-2.2 g cm（-3）级分相比，> 2.2 g cm（-3）级分具有小得多的碳浓度。该馏分中的木质素显示出迄今为止所有馏分中最强的氧化变化。我们假设，部分降解的木质素成分，不吸附到层状双氢氧化物，进行进一步的微生物氧化，直到它们形成复合物与方解石。因此，我们的结论是，在这些石灰性土壤中积累的OM主要是由于部分氧化OM的附件带正电的粘土，导致稳定对进一步分解，从而减缓营业额。在较小程度上，方解石也参与植物残留物的稳定。(c)2006爱思唯尔有限公司保留所有权利。
The mechanisms of organic matter (OM) stabilization and possible organic-mineral interactions in alkaline soils rich in Ca (calcareous soils) were investigated. We sampled soils that developed over a period of 70 years under natural succession from homogeneous calcareous and organic-free substrate resulting from industrial production. We took advantage of a shift from non-woody to woody angiosperm vegetation with increasing soil age and tracked lignin as an indicator of the fate of plant residues. Using density separation in combination with ultrasonic dispersion, four fractions were obtained: (1) free particulate OM (FPOM), (2) OM occluded within soil aggregates (OPOM), (3) heavy fraction with a density of 1.6-2.2 g cm(-3) and (4) heavy fraction with a density > 2.2 g cm(-3). The fractions were analysed for C, N, CuO oxidation products and mineral composition. Accumulation of OM by occlusion within aggregates contributed little (4-16%) to the total organic C in the soils. The dominant portion of organic C was in the fractions > 1.6 g cm(-3). Lignin phenols in the fractions > 1.6 g cm(-3) showed the most intensive diagenetic alteration as reflected in small yields of vanillic, syringic and cinnamic (VSC) lignin and stronger oxidation of the side chains of vanillyl phenols. In contrast to the POM fractions, the fractions > 1.6 g cm(-3) from the older sites conserved the non-woody angiosperm lignin signature of the former vegetation, indicating slower OM turnover. The mineral composition of the two heavy fractions clearly differed, with layered double hydroxides (i.e., hydrotalcite and hydrocalumite) dominating the fractions > 1.6 g cm(-3) and calcite dominating the fractions > 2.2 g cm(-3). We conclude that partly degraded lignin, enriched in acidic groups, accumulated in the fraction 1.62.2 g cm-(3,) due to preferential adsorption to the positively charged layered double hydroxides. Although representing only a small portion of the soil mineral assemblage, layered double hydroxides seem to be of significant relevance for OM accumulation. Over the years, the fraction 1.6-2.2 g cm(-3) comprised the largest single pool of organic C. Compared with the 1.6-2.2 g cm(-3) fraction, the > 2.2 g cm(-3) fraction had a much smaller carbon concentrations. The lignin in that fraction showed by far the strongest oxidative alteration of all the fractions. We assume that partly degraded lignin components, not adsorbed to layered double hydroxides, undergo further microbial oxidation until they form complexes with calcite. Consequently, we conclude that in these calcareous soils accumulation of OM is mainly due to the attachment of partly oxidized OM to positively charged clays, resulting in stabilization against further decomposition, thus slowing down turnover. To a minor extent, calcite is also involved in the stabilization of the plant residues. (c) 2006 Elsevier Ltd. All rights reserved.