Magnesium isotope fractionation during shale weathering in the Shale Hills Critical Zone Observatory: Accumulation of light Mg isotopes in soils by clay mineral transformation
文献类型：期刊论文
| 作者 | Ma, Lin1; Teng, Fang-Zhen2; Jin, Lixin1; Ke, Shan3; Yang, Wei4; Gu, Hai-Ou5; Brantley, Susan L.6 |
| 刊名 | CHEMICAL GEOLOGY
 |
| 出版日期 | 2015-03-18 |
| 卷号 | 397页码:37-50 |
| 关键词 | Mg Isotopes Soils And Regolith Shale Weathering Critical Zone Science Particle Transport |
| DOI | 10.1016/j.chemgeo.2015.01.010 |
| 文献子类 | Article |
| 英文摘要 | Magnesium isotopic ratios have been used as a natural tracer to study weathering processes and biogeochemical pathways in surficial environments, but few have focused on the mechanisms that control Mg isotope fractionation during shale weathering. In this study we focus on understanding Mg isotope fractionation in the Shale Hills catchment in central Pennsylvania. Mg isotope ratios were measured systematically in weathering products, along geochemical pathways of Mg during shale weathering: from bedrock to soils and soil pore water on a planar hillslope, and to sediments, stream water, and groundwater on a valley floor. Significant variations of Mg isotopic values were observed: delta Mg-26 values (-0.6% to -0.1%) of stream and soil pore waters are about similar to 0.5% to 1% lighter than the shale bedrock delta(Mg-26 values of +0.4%), consistent with previous observations that lighter Mg isotopes are preferentially released to water during silicate weathering. Dissolution of the carbonate mineral ankerite, depleted in the shallow soils but present in bedrock at greater depths, produced higher Mg2+ concentrations but lower delta Mg-26 values (-1.1%) in groundwater, similar to 1.5% lighter than the bedrock. delta Mg-26 values (+0.2% to +0.4%) of soil samples on the planar hillslope are either similar or up to similar to 0.2% lighter than the bedrock. Hence a heavy Mg isotope reservoir - complementary to the lighter Mg isotopes in soil pore water and streamwater - is missing from the residual soils on the hillslope. In addition, soil samples show a slight but systematic decreasing trend in delta Mg-26 values with increasing weathering duration towards the surface. We suggest that the accumulation of light Mg isotopes in surface soils at Shale Hills is due to a combined effect of i) sequestration of isotopically light Mg from soil water during clay dissolution-precipitation reactions; and ii) loss of isotopically heavy particulate Mg in micron-sized particles from the hillslope as suspended sediments. This latter mechanism is somewhat surprising in that most researchers do not consider physical removal or particles to be a likely mechanism of isotopic fractionation. Stream sediments (delta Mg-26 values of +0.3% to +0.5%) accumulated on the valley floor are similar to 0.2% heavier than the bedrock, and are thus consistent with that mobile particulates are the heavy Mg isotope reservoir. |
| WOS关键词 | COLLECTOR ICP-MS ; CHEMICAL-COMPOSITION ; ORGANIC-CARBON ; PLANT-GROWTH ; ALBANY SHALE ; CATCHMENT ; RIVER ; TRANSPORT ; URANIUM ; GEOCHEMISTRY |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000351671900004 |
| 资助机构 | NSF Critical Zone Observatory program(EAR 07-25019) ; NSF Critical Zone Observatory program(EAR 07-25019) ; SLB(EAR 12-39285 ; SLB(EAR 12-39285 ; Penn State's Forestland Management Office in the College of Agricultural Sciences ; Penn State's Forestland Management Office in the College of Agricultural Sciences ; Department of Energy(DE-FG02-05ER15675) ; Department of Energy(DE-FG02-05ER15675) ; CEEIR ; CEEIR ; NSF(EAR-0838227 ; NSF(EAR-0838227 ; EAR 13-31726) ; EAR 13-31726) ; EAR-1056713 ; EAR-1056713 ; EAR-1340160) ; EAR-1340160) ; NSF Critical Zone Observatory program(EAR 07-25019) ; NSF Critical Zone Observatory program(EAR 07-25019) ; SLB(EAR 12-39285 ; SLB(EAR 12-39285 ; Penn State's Forestland Management Office in the College of Agricultural Sciences ; Penn State's Forestland Management Office in the College of Agricultural Sciences ; Department of Energy(DE-FG02-05ER15675) ; Department of Energy(DE-FG02-05ER15675) ; CEEIR ; CEEIR ; NSF(EAR-0838227 ; NSF(EAR-0838227 ; EAR 13-31726) ; EAR 13-31726) ; EAR-1056713 ; EAR-1056713 ; EAR-1340160) ; EAR-1340160) |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/62560]  |
| 专题 | 地质与地球物理研究所_地球深部结构与过程研究室 |
| 作者单位 | 1.Univ Texas El Paso, Dept Geol Sci, El Paso, TX 79968 USA 2.Univ Washington, Dept Earth & Space Sci, Isotope Lab, Seattle, WA 98195 USA 3.China Univ Geosci, Sch Earth Sci & Mineral Resources, State Key Lab Geol Proc & Mineral Resources, Beijing 100083, Peoples R China 4.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earths Deep Interior, Beijing 100029, Peoples R China 5.Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei, Anhui, Peoples R China 6.Penn State Univ, Earth & Environm Syst Inst, University Pk, PA 16802 USA |
| 推荐引用方式 GB/T 7714 | Ma, Lin,Teng, Fang-Zhen,Jin, Lixin,et al. Magnesium isotope fractionation during shale weathering in the Shale Hills Critical Zone Observatory: Accumulation of light Mg isotopes in soils by clay mineral transformation[J]. CHEMICAL GEOLOGY,2015,397:37-50. |
| APA | Ma, Lin.,Teng, Fang-Zhen.,Jin, Lixin.,Ke, Shan.,Yang, Wei.,...&Brantley, Susan L..(2015).Magnesium isotope fractionation during shale weathering in the Shale Hills Critical Zone Observatory: Accumulation of light Mg isotopes in soils by clay mineral transformation.CHEMICAL GEOLOGY,397,37-50. |
| MLA | Ma, Lin,et al."Magnesium isotope fractionation during shale weathering in the Shale Hills Critical Zone Observatory: Accumulation of light Mg isotopes in soils by clay mineral transformation".CHEMICAL GEOLOGY 397(2015):37-50. |
入库方式： OAI收割
来源：地质与地球物理研究所
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