Long-term carbon storage through retention of dissolved aromatic acids by reactive particles in soil
Long-term carbon storage through retention of dissolved aromatic acids by reactive particles in soil
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DOI：
10.1111/j.1365-2486.2012.02681.x
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发表时间：
2012-08-01
影响因子：
11.6
通讯作者：
Vitousek, Peter M.
中科院分区：
文献类型：
--
作者：
Kramer, Marc G.;Sanderman, Jonathan;Vitousek, Peter M.
土壤保留了大量的碳，从而减缓了碳返回大气的速度。控制土壤中有机碳固定的机制仍然知之甚少，但对于理解土壤-气候反馈是不可或缺的。我们评估了夏威夷火山土壤的潜在源层和汇层中溶解有机碳和固体有机碳的生物化学。这些土壤来自缓坡火山屏蔽面上类似的玄武岩母质，支持相同的植被组合，但土壤矿物学和土壤碳含量随着火山基质年龄的变化而发生强烈变化。固体碳的核磁共振谱表明，最持久的矿物结合碳是由部分氧化的芳香族化合物组成，与从植物凋落物中提取的溶解有机物具有很强的化学相似性。分子混合模型表明，随着短程有序矿物含量的增加，蛋白质、脂肪、碳水化合物和焦炭含量降低，而氧化木质素和羧基/羰基含量增加。当富含溶解有机质的溶液通过BW层矿核时，芳香族化合物优先被吸附，最大的保留率出现在含有最多短程有序矿物的层中。这些矿物是活性亚稳纳米晶体，在火山土中最常见，但在几乎所有主要土壤类别中都有少量存在。我们的结果表明，短程有序矿物的长期碳储存是通过植物凋落物中溶解的芳香酸的化学滞留发生的，并沿着优先流动的路径携带到更深的B层。
Soils retain large quantities of carbon, thereby slowing its return to the atmosphere. The mechanisms governing organic carbon sequestration in soil remain poorly understood, yet are integral to understanding soil-climate feedbacks. We evaluated the biochemistry of dissolved and solid organic carbon in potential source and sink horizons across a chronosequence of volcanic soils in Hawai'i. The soils are derived from similar basaltic parent material on gently sloping volcanic shield surfaces, support the same vegetation assemblage, and yet exhibit strong shifts in soil mineralogy and soil carbon content as a function of volcanic substrate age. Solid-state13carbon nuclear magnetic resonance spectra indicate that the most persistent mineral-bound carbon is comprised of partially oxidized aromatic compounds with strong chemical resemblance to dissolved organic matter derived from plant litter. A molecular mixing model indicates that protein, lipid, carbohydrate, and char content decreased whereas oxidized lignin and carboxyl/carbonyl content increased with increasing short-range order mineral content. When solutions rich in dissolved organic matter were passed through Bw-horizon mineral cores, aromatic compounds were preferentially sorbed with the greatest retention occurring in horizons containing the greatest amount of short-range ordered minerals. These minerals are reactive metastable nanocrystals that are most common in volcanic soils, but exist in smaller amounts in nearly all major soil classes. Our results indicate that long-term carbon storage in short-range ordered minerals occurs via chemical retention with dissolved aromatic acids derived from plant litter and carried along preferential flow-paths to deeper B horizons.