Storage and export of soil carbon and mineral surface area along an erosional gradient in the Sierra Nevada, California
Storage and export of soil carbon and mineral surface area along an erosional gradient in the Sierra Nevada, California
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加利福尼亚州内华达山脉沿侵蚀梯度的土壤碳和矿物表面积的储存和输出
DOI：
10.1016/j.geoderma.2018.02.008
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发表时间：
2018
期刊：
影响因子：
6.1
通讯作者：
Wang X
中科院分区：
文献类型：
--
作者：
Wang X
陡峭的土壤覆盖山坡被认为是河流沉积物和有机碳（OC）的重要来源。这些沉积物中的矿物质可能会保护有机碳不被分解，但这种相互作用在陡峭的高地土壤中的意义仍然受到很大的限制，特别是在侵蚀速率方面。我们研究了一个流入加州中民俗羽毛河的支流流域，在那里，断点迁移创造了一系列侵蚀率在一个数量级上变化的山坡（35至250 mm kyr-1）。这种设置提供了一个独特的机会，研究土壤有机碳库和侵蚀出口的侵蚀速率的变化的函数。土壤有机碳库存低37%，在快速侵蚀的网站相对于缓慢侵蚀的网站。这种差异是由粗岩石含量驱动的，因为快速侵蚀的土壤有更多的岩石碎片，限制了它们储存有机碳的能力。虽然土壤中的粘粒含量与侵蚀速率呈负相关，总矿物比表面积保持相对不变。基于次生层状硅酸盐矿物研究土壤和我们的现场观察的腐岩，我们认为，这种差异可能源于不同的粘土矿物（类型和丰度）与不同程度的深层地下化学风化。在整个侵蚀梯度，矿物相关的有机质（MOC）在腐岩的放射性碳年龄变化的因素2（从1045年至211014 C年），而土壤周转时间估计土壤厚度和侵蚀速率变化从17到5.4千年。在侵蚀速率最快的地点，土壤周转时间接近MOC的14 C年龄，这表明侵蚀可能会限制MOC被替换的时间尺度。我们发现，有机质通常覆盖总矿物表面的50%以下。剩余的不含有机碳的矿物表面积一旦受到侵蚀，可能因此具有显著的、迄今为止尚未量化的吸附额外有机物质的能力，这些有机物质可能充当长期的大气碳汇。
Steep soil-mantled hillslopes are thought to be important sources of sediments and organic carbon (OC) to rivers. Minerals in these sediments may protect OC from decomposition, yet the significance of such interactions in steep upland soils remains poorly constrained particularly in relation to erosion rates. We examined a tributary basin draining to the Middle Folk Feather River in California, where knickpoint migration has created a series of hillslopes with erosion rates varying over an order of magnitude (35 to 250 mm kyr−1). This setting provides a unique opportunity to study soil OC pools and their erosional exports as a function of changes in erosion rates. Soil OC inventories were 37% lower at rapidly eroding sites relative to slowly eroding sites. This difference was driven by coarse rock contents as rapidly eroding soils had more rock fragments, limiting their capacities to store OC. Although clay contents in soils were negatively correlated with erosion rates, the total mineral specific surface area remained relatively invariant. Based on secondary phyllosilicate minerals present in the studied soils and our field observations of saprocks, we suggest that this discrepancy may have originated from different clay mineralogy (types and abundance) associated with different degrees of deep subsurface chemical weathering. Across the erosion gradient, the radiocarbon age of mineral associated organic matter (MOC) in saprock varied by a factor 2 (from 1045 to 211014C years), while soil turnover times estimated from soil thickness and erosion rates varied from 17 to 5.4 kyr. At the site eroding at the fastest rate, the soil turnover time approaches the14C age of MOC, suggesting erosion can potentially limit the timescale over which MOC is replaced. We found that organic matter generally covered <50% of the total mineral surface. The remaining OC-free mineral surface area, once eroded, may thus have a significant, and to date unquantified, capacity to adsorb additional organic matter, which may act as a long-term atmospheric carbon sink.
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加利福尼亚州内华达山脉最新更新世和全新世冰川作用的范围、时间和气候意义
DOI：
--
发表时间：
1995
期刊：
影响因子：
--
作者：
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通讯作者：
D. Clark
加利福尼亚州普拉玛斯国家森林梅里马克地区的变质岩和火成岩
DOI：
--
发表时间：
1951
期刊：
影响因子：
--
作者：
A. Hietanen
通讯作者：
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美国本土 ≤ 1 m 深度软风化基岩的分布和性质
影响因子：
3.3
作者：
J. Wald;R. Graham;Phillip J. Schoeneberger
通讯作者：
Phillip J. Schoeneberger
影响因子：
3.9
作者：
Almond, Peter;Roering, Josh;Hales, T. C.
通讯作者：
Hales, T. C.
影响因子：
8.3
作者：
STUIVER, M;POLACH, HA
通讯作者：
POLACH, HA