{"title":"尼泊尔喜马拉雅山脉山区河流中溶解物和颗粒物的来源与组成：从钍和钕同位素及元素比率中获得的启示","authors":"Rajendra Bhandari , Kuo-Fang Huang , Mårten Dario , Åsa Danielsson , Subodh Sharma , Joyanto Routh","doi":"10.1016/j.apgeochem.2024.106183","DOIUrl":null,"url":null,"abstract":"<div><div>The Ganga River exhibits elevated concentrations of dissolved strontium (Sr) and a higher radiogenic Sr (<sup>87</sup>Sr/<sup>86</sup>Sr) among global rivers, which impacts oceanic Sr composition. This has implications for understanding weathering and sediment flux into open oceans. The Nepal Himalayan section is a significant part of the upstream Ganga River catchment. We analyzed Sr and Nd isotopes and major element concentrations in water and sediments to trace compositional and seasonal variability in dissolved and particulate matter. The Sr and Nd isotopes, in particular, are crucial in this study as they provide unique signatures that can be used to trace the origin and composition of the dissolved and particulate matter. Representative rivers draining monolithological terrains were selected to investigate the isotopic and elemental provenance and weathering intensity. The elemental ratios (Ca/Na, Mg/Na) indicate the watersheds are carbonate-rich terrains. The Lesser Himalaya (LH) rivers transport radiogenic Sr with high values compared to rivers draining the Tethyan Sedimentary Series (TSS), Higher Himalayan Crystalline (HHC), Mahabharat, and Siwalik Hills. The dry season records a higher <sup>87</sup>Sr/<sup>86</sup>Sr ratio than the monsoon. Due to the faster dissolution of carbonates compared to silicates, monsoon waters transport less radiogenic Sr. The significant correlation of <sup>87</sup>Sr/<sup>86</sup>Sr in dissolved and particulate phases signifies that short-term interactions between sediment and water may alter the <sup>87</sup>Sr/<sup>86</sup>Sr composition. Notably, sediments originating from continental rocks exhibit an inverse correlation between <sup>87</sup>Sr/<sup>86</sup>Sr and ε<sub>Nd</sub>. In conclusion, the Sr and Nd isotopic records in this study categorize the fluvial catchments into geological clusters aligned with the TSS, LH, and Siwaliks, which advance our understanding regarding the provenance besides providing crucial insights into geological processes, weathering, landscape evolution, and sediment flux.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"175 ","pages":"Article 106183"},"PeriodicalIF":3.1000,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0883292724002889/pdfft?md5=42180089988e1e40118704d0e487fc39&pid=1-s2.0-S0883292724002889-main.pdf","citationCount":"0","resultStr":"{\"title\":\"Origin and composition of dissolved and particulate matter in mountain rivers of the Nepal Himalayas: Insights from Sr and Nd isotopes and elemental ratios\",\"authors\":\"Rajendra Bhandari , Kuo-Fang Huang , Mårten Dario , Åsa Danielsson , Subodh Sharma , Joyanto Routh\",\"doi\":\"10.1016/j.apgeochem.2024.106183\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The Ganga River exhibits elevated concentrations of dissolved strontium (Sr) and a higher radiogenic Sr (<sup>87</sup>Sr/<sup>86</sup>Sr) among global rivers, which impacts oceanic Sr composition. This has implications for understanding weathering and sediment flux into open oceans. The Nepal Himalayan section is a significant part of the upstream Ganga River catchment. We analyzed Sr and Nd isotopes and major element concentrations in water and sediments to trace compositional and seasonal variability in dissolved and particulate matter. The Sr and Nd isotopes, in particular, are crucial in this study as they provide unique signatures that can be used to trace the origin and composition of the dissolved and particulate matter. Representative rivers draining monolithological terrains were selected to investigate the isotopic and elemental provenance and weathering intensity. The elemental ratios (Ca/Na, Mg/Na) indicate the watersheds are carbonate-rich terrains. The Lesser Himalaya (LH) rivers transport radiogenic Sr with high values compared to rivers draining the Tethyan Sedimentary Series (TSS), Higher Himalayan Crystalline (HHC), Mahabharat, and Siwalik Hills. The dry season records a higher <sup>87</sup>Sr/<sup>86</sup>Sr ratio than the monsoon. Due to the faster dissolution of carbonates compared to silicates, monsoon waters transport less radiogenic Sr. The significant correlation of <sup>87</sup>Sr/<sup>86</sup>Sr in dissolved and particulate phases signifies that short-term interactions between sediment and water may alter the <sup>87</sup>Sr/<sup>86</sup>Sr composition. Notably, sediments originating from continental rocks exhibit an inverse correlation between <sup>87</sup>Sr/<sup>86</sup>Sr and ε<sub>Nd</sub>. 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引用次数: 0
摘要
在全球河流中，恒河的溶解锶（Sr）浓度较高，辐射锶（87Sr/86Sr）含量也较高，这对海洋锶的组成产生了影响。这对了解风化和沉积物流入开阔海洋具有影响。尼泊尔喜马拉雅山段是恒河上游集水区的重要组成部分。我们分析了水和沉积物中的锶和钕同位素以及主要元素浓度，以追踪溶解物和颗粒物的组成和季节变化。锶和钕同位素在这项研究中尤为重要，因为它们提供了独特的特征，可用来追踪溶解物和颗粒物的来源和组成。为研究同位素和元素来源以及风化强度，我们选择了具有代表性的河流，这些河流流经的地形都是单一岩层。元素比率（Ca/Na、Mg/Na）表明这些流域是富含碳酸盐的地形。小喜马拉雅（LH）河流的放射性 Sr 含量较高，而流经特提安沉积系列（TSS）、高喜马拉雅结晶（HHC）、摩诃哈拉特（Mahabharat）和西瓦利克山（Siwalik Hills）的河流的放射性 Sr 含量较低。旱季的 87Sr/86Sr 比率高于季风季节。溶解相和颗粒相中 87Sr/86Sr 的显著相关性表明，沉积物和水之间的短期相互作用可能会改变 87Sr/86Sr 的组成。值得注意的是，源于大陆岩石的沉积物在 87Sr/86Sr 与 εNd 之间表现出反向相关性。总之，本研究中的锶和钕同位素记录将河流集水区划分为与TSS、LH和Siwaliks相一致的地质群，除了为地质过程、风化、地貌演化和沉积物通量提供重要见解外，还推进了我们对来源的理解。
Origin and composition of dissolved and particulate matter in mountain rivers of the Nepal Himalayas: Insights from Sr and Nd isotopes and elemental ratios
The Ganga River exhibits elevated concentrations of dissolved strontium (Sr) and a higher radiogenic Sr (87Sr/86Sr) among global rivers, which impacts oceanic Sr composition. This has implications for understanding weathering and sediment flux into open oceans. The Nepal Himalayan section is a significant part of the upstream Ganga River catchment. We analyzed Sr and Nd isotopes and major element concentrations in water and sediments to trace compositional and seasonal variability in dissolved and particulate matter. The Sr and Nd isotopes, in particular, are crucial in this study as they provide unique signatures that can be used to trace the origin and composition of the dissolved and particulate matter. Representative rivers draining monolithological terrains were selected to investigate the isotopic and elemental provenance and weathering intensity. The elemental ratios (Ca/Na, Mg/Na) indicate the watersheds are carbonate-rich terrains. The Lesser Himalaya (LH) rivers transport radiogenic Sr with high values compared to rivers draining the Tethyan Sedimentary Series (TSS), Higher Himalayan Crystalline (HHC), Mahabharat, and Siwalik Hills. The dry season records a higher 87Sr/86Sr ratio than the monsoon. Due to the faster dissolution of carbonates compared to silicates, monsoon waters transport less radiogenic Sr. The significant correlation of 87Sr/86Sr in dissolved and particulate phases signifies that short-term interactions between sediment and water may alter the 87Sr/86Sr composition. Notably, sediments originating from continental rocks exhibit an inverse correlation between 87Sr/86Sr and εNd. In conclusion, the Sr and Nd isotopic records in this study categorize the fluvial catchments into geological clusters aligned with the TSS, LH, and Siwaliks, which advance our understanding regarding the provenance besides providing crucial insights into geological processes, weathering, landscape evolution, and sediment flux.
期刊介绍：
Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application.
Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.
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