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首页> 外文期刊>Chemical geology >Determining mineral weathering rates based on solid and solute weathering gradients and velocities: application to biotite weathering in saprolites
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Determining mineral weathering rates based on solid and solute weathering gradients and velocities: application to biotite weathering in saprolites

机译：基于固体和溶质的风化梯度和速度确定矿物的风化率：在腐泥土中黑云母风化中的应用

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Chemical weathering gradients are defined by the changes in the measured elemental concentrations in solids and pore waters with depth in soils and regoliths. An increase in the mineral weathering rate increases the change in these concentrations with depth while increases in the weathering velocity decrease the change. The solid-state weathering velocity is the rate at which the weathering front propagates through the regolith and the solute weathering velocity is equivalent to the rate of pore water infiltration. These relationships provide a unifying approach to calculating both solid and solute weathering rates from the respective ratios of the weathering velocities and gradients. Contemporary weathering rates based on solute residence times can be directly compared to long-term past weathering based on changes in regolith composition. Both rates incorporate identical parameters describing mineral abundance, stoichiometry, and surface area. Weathering gradients were used to calculate biotite weathering rates in saprolitic regoliths in the Piedmont of Northern Georgia, USA and in Luquillo Mountains of Puerto, Rico. Solid-state weathering gradients for Mg and K at Panola produced reaction rates of 3 to 6 x 10-(17) mol m-(2) s(-1) for biotite. Faster weathering rates of 1.8 to 3.6 x 10(-16) mol m(-2) s(-1) are calculated based on Mg and K pore water gradients in the Rio Icacos regolith. The relative rates are in agreement with a warmer and wetter tropical climate in Puerto Rico. Both natural rates are three to six orders of magnitude slower than reported experimental rates of biotite weathering. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 38]
机译：化学风化梯度是由固体和孔隙水中所测元素浓度随土壤和and石深度的变化而定义的。矿物风化速率的增加会随着深度的增加而增加这些浓度的变化，而风化速度的增加会降低这种变化。固态风化速度是风化锋面通过灰泥岩传播的速率，溶质的风化速度等于孔隙水的渗透速率。这些关系提供了一种统一的方法，可以根据风化速度和梯度的各个比率来计算固体和溶质的风化率。可以将基于溶质停留时间的当代风化率与基于硬石膏成分变化的长期过去风化率直接进行比较。两种速率均包含描述矿物质丰度，化学计量和表面积的相同参数。使用风化梯度来计算美国北部佐治亚州皮埃蒙特和波多黎各波多黎各卢克洛伊洛山脉的腐泥岩中的黑云母风化率。镁和钾在Panola上的固态风化梯度使黑云母的反应速率为3至6 x 10-（17）mol m-（2）s（-1）。根据里约伊卡科斯角砾岩中的Mg和K孔隙水梯度计算出1.8至3.6 x 10（-16）mol m（-2）s（-1）的更快风化速率。相对汇率与波多黎各的热带气候比较温暖和一致。两种自然速率都比报道的黑云母风化实验速率慢三到六个数量级。 （C）2002 Elsevier Science B.V.保留所有权利。 [参考：38]

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