Aeolian dust deposition and the perturbation of phosphorus transformations during long-term ecosystem development in a cool, semi-arid environment
Aeolian dust deposition and the perturbation of phosphorus transformations during long-term ecosystem development in a cool, semi-arid environment
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DOI：
10.1016/j.gca.2018.12.017
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发表时间：
2019-02-01
影响因子：
5
通讯作者：
Zhu, Mengqiang
中科院分区：
文献类型：
--
作者：
Gu, Chunhao;Hart, Stephen C.;Zhu, Mengqiang
风尘沉降是陆地生态系统的重要磷输入，但其对生态系统长期发展过程中磷动态的影响尚不清楚。在这项研究中，我们用P-K-EDGE XANES光谱表征了表层土壤(0-15 cm，A层)和在凉爽、半干旱环境中3000 Ky火山土壤年代序列的每个地点收集的当代风尘中的P形态。粉尘中磷的形态以钙结合磷为主(Ca-P占54-74%)，铁铝结合磷占11-23%[(Fe+Al)-P]，有机磷占7-25%。在土壤中，P-o占全P的1-23%，在老土壤中更大，但Ca-P(16-39%)和(Fe+Al)-P(48-82%)的比例随着土壤风化程度的增加而波动。这种土壤波动是由于半干旱气候条件下土壤成土过程中碱性风尘的积累和保存，显著增加了土壤钙磷含量，降低了土壤(Fe+Al)-P总量和相对丰度。我们认为，风尘输入对土壤磷转化的影响是沙尘输入的相对大小、化学成分和土壤风化强度的函数。对于给定的粉尘来源，当净粉尘通量大于风化速率时，粉尘会积累，从而改变土壤成土过程中P的转化模式；否则，对土壤P转化的影响可以忽略不计。通过准确识别磷库的化学性质，我们的工作突出了P K-EDGE XANES光谱在研究土壤磷动态方面比化学提取法的优势，并展示了粉尘输入如何修改半干旱环境中土壤磷转化的Walker和Syers模型。总体而言，这项工作为理解土壤和生态系统发展过程中粉尘如何影响磷循环奠定了基础，并表明，在陆地生态系统中开发具有预测能力的综合气候-生物地球化学模型时，必须考虑粉尘输入和组成以及土壤风化速率。爱思唯尔有限公司出版。
Aeolian dust deposition is an important phosphorus (P) input to terrestrial ecosystems, but its influence on P dynamics during long-term ecosystem development remains poorly understood. In this study, we characterized P speciation using P K-edge XANES spectroscopy in surface soils (0-15 cm, A horizon) and contemporary aeolian dust collected at each site of a 3000-ky volcanic soil chronosequence in a cool, semi-arid environment. Phosphorus speciation in dust was dominated by calcium-bound P (Ca-P; 54-74%), with 11-23% iron and aluminum-bound P [(Fe + Al)-P] and 7-25% organic P (P-o). In soils, P-o contributed 1-23% of total P, being greater in older soils; however, the proportions of Ca-P (16-39%) and (Fe + Al)-P (48-82%) fluctuated with increasing weathering over the soil chronosequence. These soil fluctuations resulted from the accumulation and preservation of alkaline aeolian dust during pedogenesis in the semi-arid climate, which significantly increased soil Ca-P while decreasing the total amounts and relative abundances of soil (Fe + Al)-P. We suggest that the effects of an aeolian dust input on soil P transformations are functions of the relative magnitude and chemical composition of the dust input and the soil weathering intensity. For a given source of dust, when the net dust flux is greater than the weathering rate, dust accumulates and thus alters the pattern of P transformations during pedogenesis; otherwise, the dust influence on soil P transformations is negligible. By accurately identifying the chemical nature of P pools, our work highlights the advantage of P K-edge XANES spectroscopy over chemical extractions in examining soil P dynamics, and demonstrates how dust inputs can modify the Walker and Syers model of pedogenic P transformations in semi-arid environments. Overall, this work provides a foundation for understanding how dust influences P cycling during soil and ecosystem development, and indicates that dust inputs and composition, and the soil weathering rate, all must be considered for developing integrated climate-biogeochemical models with predictive power in terrestrial ecosystems. Published by Elsevier Ltd.