Mineral surfaces and soil organic matter
Mineral surfaces and soil organic matter
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DOI：
10.1046/j.1365-2389.2003.00544.x
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发表时间：
2003-06-01
影响因子：
4.2
通讯作者：
Guggenberger, G
中科院分区：
文献类型：
--
作者：
Kaiser, K;Guggenberger, G
土壤的有机碳含量与比表面积（SSA）呈正相关，但土壤中大量的有机质会导致SSA降低，这是通过将Brunauer-Emmett-Teller（BET）方程应用于N-2的吸附来确定的。为了阐明这种关系的某些控制机制，我们测定了NaOCl去除有机质前后196个森林土壤矿质层中密度> 1.6 g cm（-3）的分离物的SSA和N-2吸附焓。同样，我们研究了增加有机质吸附到四种矿物土壤样品（氧化物（无定形Al（OH）（3），三水铝石，水铁矿，针铁矿，赤铁矿）和页硅酸盐（高岭石，伊利石）之前和之后的这些特性。有机质的吸附降低SSA，这取决于吸附量和矿物的类型。SSA的减少在较大的有机质负荷下降。矿质土壤的SSA与铁羟基氧化物含量呈正相关，与有机碳含量呈负相关。SSA在小负载下的强烈降低主要是由于N-2可进入的微孔的减少。这表明优先吸附的有机物质在反应性位点或在微孔的嘴在初始吸附和附件在增加负载的反应性较低的网站。气体吸附热随表面负荷的指数下降也表明在有机质积累的早期阶段微孔被填充或堵塞。解吸引起的总SSA，但不是微表面积的恢复。有机质的破坏增加了所有土壤样品的SSA。未覆盖的矿物基质的SSA强烈相关的铁羟基氧化物和粘土的量。标准化去除C，SSA的增加在富含C的灰壤的表土和淀积层中很小，而在含有少量C的底土中很大。这表明，微孔优先与有机物质，特别是在小负载。由SSA计算的有机质破坏前后土壤矿物基质表面的覆盖度仅与深度相关，且呈线性关系，说明矿物学是同一土壤层位（即层位）内表面积与有机质吸附关系的主要控制因素。但在完整剖面尺度上，有机质的表面积累和稳定还取决于其输入。
The organic carbon content of soil is positively related to the specific surface area (SSA), but large amounts of organic matter in soil result in reduced SSA as determined by applying the Brunauer-Emmett-Teller (BET) equation to the adsorption of N-2. To elucidate some of the controlling mechanisms of this relation, we determined the SSA and the enthalpy of N-2 adsorption of separates with a density > 1.6 g cm(-3) from 196 mineral horizons of forest soils before and after removal of organic matter with NaOCl. Likewise, we investigated these characteristics before and after sorption of increasing amounts of organic matter to four mineral soil samples, oxides (amorphous Al(OH)(3) , gibbsite, ferrihydrite, goethite, haematite), and phyllosilicates (kaolinite, illite).Sorption of organic matter reduced the SSA, depending on the amount sorbed and the type of mineral. The reduction in SSA decreased at larger organic matter loadings. The SSA of the mineral soils was positively related to the content of Fe oxyhydroxides and negatively related to the content of organic C. The strong reduction in SSA at small loadings was due primarily to the decrease in the micropores to which N-2 was accessible. This suggests preferential sorption of organic matter at reactive sites in or at the mouths of micropores during the initial sorption and attachment to less reactive sites at increasing loadings. The exponential decrease of the heat of gas adsorption with the surface loading points also to a filling or clogging of micropores at early stages of organic matter accumulation. Desorption induced a small recovery of the total SSA but not of the micropore surface area.Destruction of organic matter increased the SSA of all soil samples. The SSA of the uncovered mineral matrix related strongly to the amounts of Fe oxyhydroxides and the clay. Normalized to C removed, the increase in SSA was small in topsoils and illuvial horizons of Podzols rich in C and large for the subsoils containing little C. This suggests that micropores preferentially associate with organic matter, especially at small loadings. The coverage of the surface of the soil mineral matrix as calculated from the SSA before and after destruction of organic matter was correlated only with depth, and the relation appeared to be linear.We conclude that mineralogy is the primary control of the relation between surface area and sorption of organic matter within same soil compartments (i.e. horizons). But at the scale of complete profiles, the surface accumulation and stabilization of organic matter is additionally determined by its input.