Pub Date : 2024-08-30DOI: 10.1016/j.chemgeo.2024.122360
The Phanerozoic surface ocean is characterized by its high dissolved oxygen content owing to mixing with the atmosphere. However, atmospheric oxygen levels varied in the early Paleozoic and it remains unclear whether the surface ocean was susceptible to significant redox fluctuations in response to extreme environmental events. In this study, we probed the redox structures of shallow middle Cambrian marine depositional environments across the North China Platform, ranging from open tidal flats to relatively deep subtidal environments. We utilized a combination of least diagenetically altered carbonate materials (such as ooid cortices, calcimicrobes, and their fringing cements), as well as in situ element measurement and imaging techniques. By analyzing a set of redox-related elements (e.g., Ce anomaly, Zn/Fe molar ratio, Mn and Cr) and mineralogical proxies (hydrogenetic Fe oxides), we revealed a stratified redox structure in the Drumian surface oceans. Compared to earlier Drumian conditions, late Drumian surface oceans experienced significant intrusions of ferruginous waters, probably reaching into shallow subtidal environments with water depths less than 10 m. Furthermore, we identified shallow subtidal microbial O2-producing factories, characterized by dendritic Epiphyton thalli. These calcimicrobes exhibited more oxygenated signatures (negative Ce anomalies and enrichment of hydrogenetic Fe oxides) relative to contemporaneous less oxic shallower and deeper environments. This finding indicates that they produced oxygen oases or refuges during periods of both normal and poor dissolved O2 conditions. This study has the potential to broaden our understanding of redox conditions and microbial oxygen-producing mechanisms in the surface ocean, particularly during intervals characterized by low atmospheric oxygen levels or episodic anoxic events.
{"title":"Intense intrusion of low-oxygen waters into mid-Cambrian surface ocean carbonate factories","authors":"","doi":"10.1016/j.chemgeo.2024.122360","DOIUrl":"10.1016/j.chemgeo.2024.122360","url":null,"abstract":"<div><p>The Phanerozoic surface ocean is characterized by its high dissolved oxygen content owing to mixing with the atmosphere. However, atmospheric oxygen levels varied in the early Paleozoic and it remains unclear whether the surface ocean was susceptible to significant redox fluctuations in response to extreme environmental events. In this study, we probed the redox structures of shallow middle Cambrian marine depositional environments across the North China Platform, ranging from open tidal flats to relatively deep subtidal environments. We utilized a combination of least diagenetically altered carbonate materials (such as ooid cortices, calcimicrobes, and their fringing cements), as well as in situ element measurement and imaging techniques. By analyzing a set of redox-related elements (e.g., Ce anomaly, Zn/Fe molar ratio, Mn and Cr) and mineralogical proxies (hydrogenetic Fe oxides), we revealed a stratified redox structure in the Drumian surface oceans. Compared to earlier Drumian conditions, late Drumian surface oceans experienced significant intrusions of ferruginous waters, probably reaching into shallow subtidal environments with water depths less than 10 m. Furthermore, we identified shallow subtidal microbial O<sub>2</sub>-producing factories, characterized by dendritic <em>Epiphyton</em> thalli. These calcimicrobes exhibited more oxygenated signatures (negative Ce anomalies and enrichment of hydrogenetic Fe oxides) relative to contemporaneous less oxic shallower and deeper environments. This finding indicates that they produced oxygen oases or refuges during periods of both normal and poor dissolved O<sub>2</sub> conditions. This study has the potential to broaden our understanding of redox conditions and microbial oxygen-producing mechanisms in the surface ocean, particularly during intervals characterized by low atmospheric oxygen levels or episodic anoxic events.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142144019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1016/j.chemgeo.2024.122370
<div><div>Land use changes are known to alter terrestrial silicon cycling and the export of dissolved silicon from soil to fluvial systems, but the impact of such changes on groundwater systems remain unclear. In order to identify the processes responsible for groundwater geochemistry and to assess the impact of agricultural processes, we examined multiple isotopic tracers (δ<sup>30</sup>Si, oxygen (δ<sup>18</sup>O) and hydrogen (δ<sup>2</sup>H) isotopes) in groundwater, soil porewater and surface water from two contrasted watersheds having the same gneissic lithology, one forested (Mule Hole) and one intensely cultivated (Berambadi) in the Kabini basin in South India. In the cultivated watershed, groundwater exhibits high Cl<sup>−</sup> and NO<sub>3</sub><sup>−</sup> concentrations indicative of fertilizer inputs and solute enrichment from evapotranspiration due to multiple groundwater pumping/recharge cycles. The DSi concentration in groundwater is significantly higher in the cultivated watershed (980 ± 313 μM) than in the forested one (711 ± 154 μM), indicating more intense evapotranspiration due to irrigation cycles. The groundwater δ<sup>30</sup>Si values ranged from 0.6 ‰ to 3.4 ‰ and exhibit no significant differences between cultivated (1.2 ± 0.5 ‰) and forested (1.0 ± 0.2 ‰) watersheds, indicating limited impact of land use and land cover. Groundwater also shows no significant seasonal differences in DSi and δ<sup>30</sup>Si within watersheds, indicating a buffer to seasonal recharge during wet season. The δ<sup>30</sup>Si of a majority of groundwater samples fits a steady-state open flow through system, with an isotopic fractionation factor (<sup>30</sup>ε) between precipitating phase and groundwater ranging from −1.0 ‰ and − 2.0 ‰, consistent with precipitation of kaolinite-type clays, dominant in the study area. The steady-state flow through system in groundwater can be interpreted as a continuous DSi input from mineral weathering reactions with a dynamic equilibrium between Si supply and precipitation of secondary phases. We also observe, in both watersheds, similar DSi and δ<sup>30</sup>Si values in local surface water that includes small streams and a river (406 ± 194 μM, 1.6 ± 0.3 ‰) and in soil porewater (514 ± 119 μM, 1.6 ± 0.2 ‰). Compared to soil porewater, groundwater exhibits significantly lower δ<sup>30</sup>Si signatures and higher DSi, reflecting the contribution of an isotopically light silicon source, resulting from water-rock interaction during percolation through the unsaturated zone. We assign this steady input of DSi to the weathering of primary silicate minerals in the regolith, such as Na-plagioclase, biotite and chlorite, with formation of kaolinite and smectites type clays. A simple isotopic mass balance suggests that deep regolith weathering can contribute to almost half of the DSi in groundwater. We conclude that silicon cycling in soil porewaters, and surface waters are directly impacted by land use, while th
{"title":"Deep regolith weathering controls δ30Si composition of groundwater under contrasting landuse in tropical watersheds","authors":"","doi":"10.1016/j.chemgeo.2024.122370","DOIUrl":"10.1016/j.chemgeo.2024.122370","url":null,"abstract":"<div><div>Land use changes are known to alter terrestrial silicon cycling and the export of dissolved silicon from soil to fluvial systems, but the impact of such changes on groundwater systems remain unclear. In order to identify the processes responsible for groundwater geochemistry and to assess the impact of agricultural processes, we examined multiple isotopic tracers (δ<sup>30</sup>Si, oxygen (δ<sup>18</sup>O) and hydrogen (δ<sup>2</sup>H) isotopes) in groundwater, soil porewater and surface water from two contrasted watersheds having the same gneissic lithology, one forested (Mule Hole) and one intensely cultivated (Berambadi) in the Kabini basin in South India. In the cultivated watershed, groundwater exhibits high Cl<sup>−</sup> and NO<sub>3</sub><sup>−</sup> concentrations indicative of fertilizer inputs and solute enrichment from evapotranspiration due to multiple groundwater pumping/recharge cycles. The DSi concentration in groundwater is significantly higher in the cultivated watershed (980 ± 313 μM) than in the forested one (711 ± 154 μM), indicating more intense evapotranspiration due to irrigation cycles. The groundwater δ<sup>30</sup>Si values ranged from 0.6 ‰ to 3.4 ‰ and exhibit no significant differences between cultivated (1.2 ± 0.5 ‰) and forested (1.0 ± 0.2 ‰) watersheds, indicating limited impact of land use and land cover. Groundwater also shows no significant seasonal differences in DSi and δ<sup>30</sup>Si within watersheds, indicating a buffer to seasonal recharge during wet season. The δ<sup>30</sup>Si of a majority of groundwater samples fits a steady-state open flow through system, with an isotopic fractionation factor (<sup>30</sup>ε) between precipitating phase and groundwater ranging from −1.0 ‰ and − 2.0 ‰, consistent with precipitation of kaolinite-type clays, dominant in the study area. The steady-state flow through system in groundwater can be interpreted as a continuous DSi input from mineral weathering reactions with a dynamic equilibrium between Si supply and precipitation of secondary phases. We also observe, in both watersheds, similar DSi and δ<sup>30</sup>Si values in local surface water that includes small streams and a river (406 ± 194 μM, 1.6 ± 0.3 ‰) and in soil porewater (514 ± 119 μM, 1.6 ± 0.2 ‰). Compared to soil porewater, groundwater exhibits significantly lower δ<sup>30</sup>Si signatures and higher DSi, reflecting the contribution of an isotopically light silicon source, resulting from water-rock interaction during percolation through the unsaturated zone. We assign this steady input of DSi to the weathering of primary silicate minerals in the regolith, such as Na-plagioclase, biotite and chlorite, with formation of kaolinite and smectites type clays. A simple isotopic mass balance suggests that deep regolith weathering can contribute to almost half of the DSi in groundwater. We conclude that silicon cycling in soil porewaters, and surface waters are directly impacted by land use, while th","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1016/j.chemgeo.2024.122366
<div><p>Canadian Shield groundwater characterization studies have been conducted over the last four decades through operating mines, underground research areas, and wells installed for a variety of purposes. A newly available database containing chemical and isotopic analytical results of groundwaters includes data from all of these sources and spans the Canadian Shield. The Precambrian Canadian Shield Groundwater and Gas Geochemistry (PCSG<sup>3</sup>) database provides the most comprehensive data of groundwater chemistry in the Canadian Shield region to date. In this initial review of the PCSG<sup>3</sup> database, major ion, Br, water type, δ<sup>18</sup>O, δ<sup>2</sup>H and <sup>3</sup>H trends with depth and salinity are described. In future reviews, other aspects of the database will be examined, including minor and trace elements, other isotopes, and gases. The PCSG<sup>3</sup> database is comprised of 69 % freshwaters, mostly found at depths <1000 m, and dominated by Ca-HCO<sub>3</sub> and Na-HCO<sub>3</sub> water types; 17 % brackish waters, at depths <2000 m, and dominated by Na<img>Cl, Ca<img>Cl, Ca-HCO<sub>3</sub>, and Ca-SO<sub>4</sub> water types; 9 % saline waters, mostly at depths >1000 m, and dominated by Ca<img>Cl, Na<img>Cl, Ca-HCO<sub>3</sub>, and Na-HCO<sub>3</sub> water types; and 4 % brine samples, identified at depths up to 1800 m, composed entirely of Ca<img>Cl water types. An increase in all major ion and Br concentrations with depth is observed, except for HCO<sub>3</sub>, with groundwaters typically becoming more saline with depth. Variability in salinities at specific depths and at individual sites across the Canadian Shield reflect the effect of (primarily) anthropogenically induced mixing, although heterogeneous geology and hydrogeologic flow paths are also important. When eliminating data that are likely affected by anthropogenically-induced mixing, saline waters are the most affected, with median depths of Na<img>Cl and Ca<img>Cl type waters shifting downward, and median concentrations of Na<img>Cl type waters increasing. The isotopic data indicate that groundwaters from across the Canadian Shield reflect a variety of water recharge sources, with many samples plotting along the Global Meteoric Water Line (GMWL). Deviations to the right of the GMWL are indicative of freezing and mixing with drill fluid, while deviations to the left are indicative of isotopic exchange between water and rock and/or silicate hydration over long time scales. Rock/silicate-water interactions over hundreds of million of years resulted in development and isolation of Ca<img>Cl brines at multiple locations. Cold climate processes, including glacial meltwater recharge and/or ionic concentration during permafrost formation, yielded a third end-member. A conceptual model of the expected groundwater chemistry variation with depth across the Canadian Shield is presented based on an evaluation of the variation of water type and salinit
{"title":"A review of the major chemical and isotopic characteristics of groundwater in crystalline rocks of the Canadian Shield","authors":"","doi":"10.1016/j.chemgeo.2024.122366","DOIUrl":"10.1016/j.chemgeo.2024.122366","url":null,"abstract":"<div><p>Canadian Shield groundwater characterization studies have been conducted over the last four decades through operating mines, underground research areas, and wells installed for a variety of purposes. A newly available database containing chemical and isotopic analytical results of groundwaters includes data from all of these sources and spans the Canadian Shield. The Precambrian Canadian Shield Groundwater and Gas Geochemistry (PCSG<sup>3</sup>) database provides the most comprehensive data of groundwater chemistry in the Canadian Shield region to date. In this initial review of the PCSG<sup>3</sup> database, major ion, Br, water type, δ<sup>18</sup>O, δ<sup>2</sup>H and <sup>3</sup>H trends with depth and salinity are described. In future reviews, other aspects of the database will be examined, including minor and trace elements, other isotopes, and gases. The PCSG<sup>3</sup> database is comprised of 69 % freshwaters, mostly found at depths <1000 m, and dominated by Ca-HCO<sub>3</sub> and Na-HCO<sub>3</sub> water types; 17 % brackish waters, at depths <2000 m, and dominated by Na<img>Cl, Ca<img>Cl, Ca-HCO<sub>3</sub>, and Ca-SO<sub>4</sub> water types; 9 % saline waters, mostly at depths >1000 m, and dominated by Ca<img>Cl, Na<img>Cl, Ca-HCO<sub>3</sub>, and Na-HCO<sub>3</sub> water types; and 4 % brine samples, identified at depths up to 1800 m, composed entirely of Ca<img>Cl water types. An increase in all major ion and Br concentrations with depth is observed, except for HCO<sub>3</sub>, with groundwaters typically becoming more saline with depth. Variability in salinities at specific depths and at individual sites across the Canadian Shield reflect the effect of (primarily) anthropogenically induced mixing, although heterogeneous geology and hydrogeologic flow paths are also important. When eliminating data that are likely affected by anthropogenically-induced mixing, saline waters are the most affected, with median depths of Na<img>Cl and Ca<img>Cl type waters shifting downward, and median concentrations of Na<img>Cl type waters increasing. The isotopic data indicate that groundwaters from across the Canadian Shield reflect a variety of water recharge sources, with many samples plotting along the Global Meteoric Water Line (GMWL). Deviations to the right of the GMWL are indicative of freezing and mixing with drill fluid, while deviations to the left are indicative of isotopic exchange between water and rock and/or silicate hydration over long time scales. Rock/silicate-water interactions over hundreds of million of years resulted in development and isolation of Ca<img>Cl brines at multiple locations. Cold climate processes, including glacial meltwater recharge and/or ionic concentration during permafrost formation, yielded a third end-member. A conceptual model of the expected groundwater chemistry variation with depth across the Canadian Shield is presented based on an evaluation of the variation of water type and salinit","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009254124004467/pdfft?md5=ee5f3db7b80f13387683d0459334bd5f&pid=1-s2.0-S0009254124004467-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122364
Segregation of granitic melts from their reservoir is a key process in the genesis of granites. However, the melt segregation mechanism is still enigmatic because the ability for the segregation of the melts from their magma reservoir decreases with decreasing temperature. Two complementary lithologic units have been identified in the Beidashan pluton of NE China, based on reverse mineral zoning, rimward temperature-increasing pattern in minerals, and their contrasting whole rock Rb/Ba and Zr/Hf ratios, Ba and Zr concentrations, and alkali feldspar BaO and biotite F contents. One of the units represents a crystallized crystal-poor granitic melt, and the other represents a melt-poor crystal mush with many igneous mafic enclaves. The genesis of the two units can be explained by the removal of the crystal-poor high-silica granitic melt from a complementary mushy reservoir. We also show that granitic melts can be efficiently segregated from their mushy reservoir. This is caused by fluxed melting and melt expulsion in a temperature-increasing condition driven by high-temperature gas sparging from mafic recharge when it quenched at the base of the overlying felsic mushy reservoir. The segregated granitic melts formed by this mechanism are significantly higher in temperature than their water-saturated solidus and, thus can ascend to a very shallow crustal level away from their mushy reservoir. Our model can explain many observations that rare complementary cumulates are reported accompanying high-silica granites. Furthermore, the study proposes a robust petrological, mineralogical, and geochemical identification signature of high-temperature granitic cumulates after removing complementary high-silica granitic melt.
花岗岩熔体与其储层的分离是花岗岩成因的一个关键过程。然而，由于熔体与岩浆储层的分离能力随温度的降低而减弱，因此熔体分离机制仍然是一个谜。根据反向矿物分带、矿物的边缘温度递增模式，以及全岩 Rb/Ba 和 Zr/Hf 比值、Ba 和 Zr 浓度、碱性长石 BaO 和生物长石 F 含量的对比，在中国东北部的北大山岩浆岩中确定了两个互补岩性单元。其中一个单元代表了贫晶花岗岩熔体，另一个单元代表了贫晶花岗岩熔泥，其中有许多火成岩黑云母飞地。这两个单元的成因可以用贫晶高硅花岗岩熔体从互补的泥质储层中移出来解释。我们还表明，花岗岩熔体可以从其粘土储层中有效地分离出来。这是由于在上覆长石泥质储层底部淬火时，黑云母充注的高温气体喷射所驱动的温度上升条件下的通量熔融和熔体排出造成的。在这种机制下形成的分离花岗岩熔体的温度大大高于其水饱和固结物的温度，因此可以上升到非常浅的地壳层面，远离其稠密储层。我们的模型可以解释许多关于高硅花岗岩伴生罕见补积物的观察结果。此外，该研究还提出了在剔除互补的高硅花岗岩熔体后，高温花岗岩积岩的岩石学、矿物学和地球化学识别特征。
{"title":"Efficient segregation of high-silica granitic melt from complementary cumulate caused by high-temperature gas sparging from mafic recharge","authors":"","doi":"10.1016/j.chemgeo.2024.122364","DOIUrl":"10.1016/j.chemgeo.2024.122364","url":null,"abstract":"<div><p>Segregation of granitic melts from their reservoir is a key process in the genesis of granites. However, the melt segregation mechanism is still enigmatic because the ability for the segregation of the melts from their magma reservoir decreases with decreasing temperature. Two complementary lithologic units have been identified in the Beidashan pluton of NE China, based on reverse mineral zoning, rimward temperature-increasing pattern in minerals, and their contrasting whole rock Rb/Ba and Zr/Hf ratios, Ba and Zr concentrations, and alkali feldspar BaO and biotite F contents. One of the units represents a crystallized crystal-poor granitic melt, and the other represents a melt-poor crystal mush with many igneous mafic enclaves. The genesis of the two units can be explained by the removal of the crystal-poor high-silica granitic melt from a complementary mushy reservoir. We also show that granitic melts can be efficiently segregated from their mushy reservoir. This is caused by fluxed melting and melt expulsion in a temperature-increasing condition driven by high-temperature gas sparging from mafic recharge when it quenched at the base of the overlying felsic mushy reservoir. The segregated granitic melts formed by this mechanism are significantly higher in temperature than their water-saturated solidus and, thus can ascend to a very shallow crustal level away from their mushy reservoir. Our model can explain many observations that rare complementary cumulates are reported accompanying high-silica granites. Furthermore, the study proposes a robust petrological, mineralogical, and geochemical identification signature of high-temperature granitic cumulates after removing complementary high-silica granitic melt.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122350
The stable oxygen isotope ratios of whole tree-ring α-cellulose (δ18OWR) have been interpreted as an indicator of early summer hydroclimate in the Meiyu region of East Asia. However, the underlying physical mechanism often remains unclear. Here we provide a mechanistic understanding through intra-annual tree-ring oxygen isotope analysis and process-based δ18OWR modelling over the period 1979–2006. The selected tree species for analysis is Pinus taiwanensis, whose δ18OWR exhibit the strongest linear relationship with relative humidity (RH) in June. The results indicated that the June RH signal is predominantly contained in tree-ring earlywood rather than latewood. The strong response of δ18OWR to June RH is not due to the legacy effect. Using the proxy system model (PSM) of δ18OWR, we obtained a modeled δ18OWR time series that is significantly positively correlated with the measured δ18OWR time series. The modeled and measured δ18OWR series show similar relationships with monthly RH. Sensitivity experiments with PSM revealed that the June RH signal is originated from the oxygen isotopes of source water and leaf water. Rapid cellulose formation in June plays a role in enhancing the June RH signal. Our study demonstrates how δ18OWR record early summer hydroclimate signals from a process perspective, and that the PSM is effective in modelling the interannual δ18OWR variability in the Meiyu region.
{"title":"Deciphering the transfer of hydroclimate signals to tree-ring δ18O using a proxy system model in East Asia's Meiyu region","authors":"","doi":"10.1016/j.chemgeo.2024.122350","DOIUrl":"10.1016/j.chemgeo.2024.122350","url":null,"abstract":"<div><p>The stable oxygen isotope ratios of whole tree-ring α-cellulose (δ<sup>18</sup>O<sub>WR</sub>) have been interpreted as an indicator of early summer hydroclimate in the Meiyu region of East Asia. However, the underlying physical mechanism often remains unclear. Here we provide a mechanistic understanding through intra-annual tree-ring oxygen isotope analysis and process-based δ<sup>18</sup>O<sub>WR</sub> modelling over the period 1979–2006. The selected tree species for analysis is <em>Pinus taiwanensis</em>, whose δ<sup>18</sup>O<sub>WR</sub> exhibit the strongest linear relationship with relative humidity (RH) in June. The results indicated that the June RH signal is predominantly contained in tree-ring earlywood rather than latewood. The strong response of δ<sup>18</sup>O<sub>WR</sub> to June RH is not due to the legacy effect. Using the proxy system model (PSM) of δ<sup>18</sup>O<sub>WR</sub>, we obtained a modeled δ<sup>18</sup>O<sub>WR</sub> time series that is significantly positively correlated with the measured δ<sup>18</sup>O<sub>WR</sub> time series. The modeled and measured δ<sup>18</sup>O<sub>WR</sub> series show similar relationships with monthly RH. Sensitivity experiments with PSM revealed that the June RH signal is originated from the oxygen isotopes of source water and leaf water. Rapid cellulose formation in June plays a role in enhancing the June RH signal. Our study demonstrates how δ<sup>18</sup>O<sub>WR</sub> record early summer hydroclimate signals from a process perspective, and that the PSM is effective in modelling the interannual δ<sup>18</sup>O<sub>WR</sub> variability in the Meiyu region.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142096686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122351
<div><p>Understanding the mechanisms that drive spatial and temporal triple oxygen isotope (Δ′<sup>17</sup>O) variations in modern precipitation is the first step to expanding the utility of these measurements as an environmental tracer jointly with traditional stable isotope parameters δD, δ<sup>18</sup>O, and d-excess. However, “totalizers” designed to collect a single precipitation sample pooled over a calendar month and minimize evaporation and associated isotopic fractionation of the sample during that time have not been tested for Δ′<sup>17</sup>O. We conducted a 30-day laboratory experiment comparing mass losses and isotopic shifts in four totalizers: 1) the OPEnS (Openly Published Environmental Sensing) totalizer, 2) the classic oil-based totalizer, 3) the commercial tube dip-in/pressure equilibration totalizer (Palmex Ltd. RS1), and 4) a reference totalizer (the control, lacking any evaporation reduction mechanism). The OPEnS totalizer was designed as being readily user built with parts costs of about $10, oil-free to facilitate quick and easy sample preparation and risk-free sample analysis, and its collection device expands as it fills to maintain a small gas/water ratio and minimize internal evaporative losses. All totalizers were filled to 12 % of their 3-L volume and placed in a modified laboratory oven with a diurnal temperature change of 23 to 40 °C and an average relative humidity of 9.1 % to simulate extreme evaporative conditions. The OPEnS totalizer experienced the smallest mass loss of water (0.21 %) and smallest isotopic shifts (<em>p</em> < 0.05 for δ<sup>18</sup>O and d-excess), which were all within measurement error. The oil, tube, and reference totalizers showed larger mass losses (0.41, 1.37, and 1.61 %, respectively) and evaporative enrichment with respect to δD (+0.3, +0.8, and + 2.1 ‰), δ<sup>18</sup>O (+0.16, +0.23, and + 0.83 ‰), and d-excess (−0.9, −1.0, and − 4.5 ‰). The Δ′<sup>17</sup>O variations for all totalizers were within measurement error, so we suggest that in less harsh climates their triple oxygen isotope changes during secondary evaporation would be more acceptable. To test the OPEnS totalizer in field settings, we installed it alongside oil totalizers to collect monthly precipitation over three years in the towns of Jolly and San Antonio, Texas, with mean annual precipitation, temperature, and windspeed values of 556 and 563 mm, 18.7 and 21.9 °C, and 5.0 and 3.5 m/s, respectively. Results indicate that the OPEnS and oil totalizers can produce similar isotopic data in the field, but modifications to OPEnS have been implemented to minimize under-catch and stabilize the collection component where high winds are present and additional testing under a variety of environmental conditions is ongoing. OPEnS is scalable according to expected monthly precipitation amounts, providing a cost-effective, high-performance device for quantification of total rainfall and its isotopic composition without oil conta
{"title":"Testing triple oxygen isotope preservation in the new OPEnS totalizer against conventional monthly rainfall collectors","authors":"","doi":"10.1016/j.chemgeo.2024.122351","DOIUrl":"10.1016/j.chemgeo.2024.122351","url":null,"abstract":"<div><p>Understanding the mechanisms that drive spatial and temporal triple oxygen isotope (Δ′<sup>17</sup>O) variations in modern precipitation is the first step to expanding the utility of these measurements as an environmental tracer jointly with traditional stable isotope parameters δD, δ<sup>18</sup>O, and d-excess. However, “totalizers” designed to collect a single precipitation sample pooled over a calendar month and minimize evaporation and associated isotopic fractionation of the sample during that time have not been tested for Δ′<sup>17</sup>O. We conducted a 30-day laboratory experiment comparing mass losses and isotopic shifts in four totalizers: 1) the OPEnS (Openly Published Environmental Sensing) totalizer, 2) the classic oil-based totalizer, 3) the commercial tube dip-in/pressure equilibration totalizer (Palmex Ltd. RS1), and 4) a reference totalizer (the control, lacking any evaporation reduction mechanism). The OPEnS totalizer was designed as being readily user built with parts costs of about $10, oil-free to facilitate quick and easy sample preparation and risk-free sample analysis, and its collection device expands as it fills to maintain a small gas/water ratio and minimize internal evaporative losses. All totalizers were filled to 12 % of their 3-L volume and placed in a modified laboratory oven with a diurnal temperature change of 23 to 40 °C and an average relative humidity of 9.1 % to simulate extreme evaporative conditions. The OPEnS totalizer experienced the smallest mass loss of water (0.21 %) and smallest isotopic shifts (<em>p</em> < 0.05 for δ<sup>18</sup>O and d-excess), which were all within measurement error. The oil, tube, and reference totalizers showed larger mass losses (0.41, 1.37, and 1.61 %, respectively) and evaporative enrichment with respect to δD (+0.3, +0.8, and + 2.1 ‰), δ<sup>18</sup>O (+0.16, +0.23, and + 0.83 ‰), and d-excess (−0.9, −1.0, and − 4.5 ‰). The Δ′<sup>17</sup>O variations for all totalizers were within measurement error, so we suggest that in less harsh climates their triple oxygen isotope changes during secondary evaporation would be more acceptable. To test the OPEnS totalizer in field settings, we installed it alongside oil totalizers to collect monthly precipitation over three years in the towns of Jolly and San Antonio, Texas, with mean annual precipitation, temperature, and windspeed values of 556 and 563 mm, 18.7 and 21.9 °C, and 5.0 and 3.5 m/s, respectively. Results indicate that the OPEnS and oil totalizers can produce similar isotopic data in the field, but modifications to OPEnS have been implemented to minimize under-catch and stabilize the collection component where high winds are present and additional testing under a variety of environmental conditions is ongoing. OPEnS is scalable according to expected monthly precipitation amounts, providing a cost-effective, high-performance device for quantification of total rainfall and its isotopic composition without oil conta","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142096579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122359
<div><p>The Devonian Wengeqi mafic–ultramafic intrusion, situated on the northern margin of the North China Craton (NCC) — an Andean-style convergent margin during the Paleozoic — hosts many platinum-group minerals (PGMs), especially within the S-deficient, magnetite-rich clinopyroxenite zones. These PGMs occur in two distinct associations: Pt-rich PGMs (e.g., sperrylite) closely associated with primary magnetite and Pd-rich PGMs (e.g., sudburyite, kotuskite, arsenopalladinite) associated with secondary minerals (e.g., actinolite, pyrite). The mechanisms underlying the formation of PGMs in S-deficient rocks and the spatial decoupling of various PGM types remain elusive. The relationship of PGM formation and characteristics of magmas at convergent margins is also not well understood. In this contribution, we utilized apatite and clinopyroxene textures and chemistry alongside whole-rock Sr<img>Nd isotopes to characterize i) the nature of the parental magma from which the Wengeqi intrusion crystallized, and ii) the magmatic–hydrothermal processes that operated to generate the Pt- and Pd-rich PGM. Based on the composition of clinopyroxene and clinopyroxene–melt partition coefficients, the parental magma of the Wengeqi intrusion is estimated to have an arc-like affinity on a primitive mantle-normalized trace-element diagram. This, together with the EMI-like Sr<img>Nd isotope signature, implies that the Wengeqi magma was sourced from metasomatized SCLM beneath the NCC with an EMI-like composition. Three types of apatite (Ap1, Ap2, and Ap3) were identified within the intrusion. Ap1 and Ap2 are magmatic in origin, and appear as isolated grains, whereas Ap3 occurs as stringers or heterogeneous domains within Ap1 and Ap2, and likely resulted from hydrothermal modification of magmatic apatite. Notably, the abundant Ap2 exhibits higher V<img>S contents and Eu/Eu* ratios than the less common Ap1, and contains S predominantly in the form of S<sup>6+</sup>, suggesting that the Wengeqi magma was relatively oxidized, with <em>f</em>O<sub>2</sub> > FMQ + 1.2. Based on the chemistry of magmatic apatite, the Wengeqi magma had ∼5 wt% H<sub>2</sub>O, which, together with its high <em>f</em>O<sub>2</sub>, facilitated crystallization of magnetite, causing reduction of the magma by removal of Fe<sup>3+</sup>. This reduction process promoted PGM nucleation by decreasing PGE solubility in the magma, leading to the association of PGM with magnetite. Additionally, the oxidized, H<sub>2</sub>O-rich magma likely released oxidizing fluids, selectively mobilizing Pd rather than Pt, separating Pt-rich PGMs from Pd-rich PGMs. The budget of PGE in the parental magma could have been increased by i) metasomatism of the SCLM source (e.g., by carbonatitic fluids), which would have elevated the concentration of PGE in the mantle source, and ii) the high <em>f</em>O<sub>2</sub> and H<sub>2</sub>O levels of the magma, which would have delayed sulfide saturation. Accordingly, mantle met
{"title":"Apatite and pyroxene as records of magmatic–hydrothermal processes and platinum-group mineral (PGM) formation in the Wengeqi mafic–ultramafic intrusion, Inner Mongolia, China: The role of oxidized, H2O-rich magmas","authors":"","doi":"10.1016/j.chemgeo.2024.122359","DOIUrl":"10.1016/j.chemgeo.2024.122359","url":null,"abstract":"<div><p>The Devonian Wengeqi mafic–ultramafic intrusion, situated on the northern margin of the North China Craton (NCC) — an Andean-style convergent margin during the Paleozoic — hosts many platinum-group minerals (PGMs), especially within the S-deficient, magnetite-rich clinopyroxenite zones. These PGMs occur in two distinct associations: Pt-rich PGMs (e.g., sperrylite) closely associated with primary magnetite and Pd-rich PGMs (e.g., sudburyite, kotuskite, arsenopalladinite) associated with secondary minerals (e.g., actinolite, pyrite). The mechanisms underlying the formation of PGMs in S-deficient rocks and the spatial decoupling of various PGM types remain elusive. The relationship of PGM formation and characteristics of magmas at convergent margins is also not well understood. In this contribution, we utilized apatite and clinopyroxene textures and chemistry alongside whole-rock Sr<img>Nd isotopes to characterize i) the nature of the parental magma from which the Wengeqi intrusion crystallized, and ii) the magmatic–hydrothermal processes that operated to generate the Pt- and Pd-rich PGM. Based on the composition of clinopyroxene and clinopyroxene–melt partition coefficients, the parental magma of the Wengeqi intrusion is estimated to have an arc-like affinity on a primitive mantle-normalized trace-element diagram. This, together with the EMI-like Sr<img>Nd isotope signature, implies that the Wengeqi magma was sourced from metasomatized SCLM beneath the NCC with an EMI-like composition. Three types of apatite (Ap1, Ap2, and Ap3) were identified within the intrusion. Ap1 and Ap2 are magmatic in origin, and appear as isolated grains, whereas Ap3 occurs as stringers or heterogeneous domains within Ap1 and Ap2, and likely resulted from hydrothermal modification of magmatic apatite. Notably, the abundant Ap2 exhibits higher V<img>S contents and Eu/Eu* ratios than the less common Ap1, and contains S predominantly in the form of S<sup>6+</sup>, suggesting that the Wengeqi magma was relatively oxidized, with <em>f</em>O<sub>2</sub> > FMQ + 1.2. Based on the chemistry of magmatic apatite, the Wengeqi magma had ∼5 wt% H<sub>2</sub>O, which, together with its high <em>f</em>O<sub>2</sub>, facilitated crystallization of magnetite, causing reduction of the magma by removal of Fe<sup>3+</sup>. This reduction process promoted PGM nucleation by decreasing PGE solubility in the magma, leading to the association of PGM with magnetite. Additionally, the oxidized, H<sub>2</sub>O-rich magma likely released oxidizing fluids, selectively mobilizing Pd rather than Pt, separating Pt-rich PGMs from Pd-rich PGMs. The budget of PGE in the parental magma could have been increased by i) metasomatism of the SCLM source (e.g., by carbonatitic fluids), which would have elevated the concentration of PGE in the mantle source, and ii) the high <em>f</em>O<sub>2</sub> and H<sub>2</sub>O levels of the magma, which would have delayed sulfide saturation. Accordingly, mantle met","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S000925412400439X/pdfft?md5=f963bad0e70dbbc5c67102862bfb286e&pid=1-s2.0-S000925412400439X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122362
Several locations with alkaline magmatism are recognised in Silurian-Devonian basins along the southern variscan autochthon units (e.g. Central Iberian Zone) of the northern Gondwana margin. The origin of the Devonian basins and their magmatism has not been studied in the context of the passive margin of Gondwana. The basement of Menorca, Balearic Islands, consists of a deep Devonian-Carboniferous basin with mafic igneous rocks, the Tramuntana Gabbros. In this study, we trace the geodynamic setting and isotopic sources of the Tramuntana Gabbros through elemental geochemistry, isotopic geochemistry (SrNd) and UPb geochronology in zircons. These gabbros are the product of an intraplate alkaline magmatism with immobile trace element and REE contents similar to those of Ocean Island Basalts. Average 87Sr/86Sr(370) of 0.708456 and εNd(370) of +4.0 indicate a source similar to a Type-2 enriched mantle with average TDM of 665 Ma, suggesting a relatively old metasomatized mantle. Concordant UPb ages of c. 597 Ma (Ediacaran, radiometric age) from a single population of 31 zircons separated from the Tramuntana Gabbros (Devonian, biostratigraphic age) reinforce the presence of older units in the corresponding lithospheric mantle. The Tramuntana Gabbros and the Devonian-Carboniferous sequences of Menorca limit the westward extension of the Paleo-Tethys Ocean, whose development never reached these westernmost regions. Assuming a common sublithospheric mantle source for the peri-Gondwanic Devonian alkaline rocks and considering the previous Cadomian (Neoproterozoic) subduction to be the most favourable origin of the separated zircons, the bulk rock TDM and zircon UPb data obtained from the Tramuntana Gabbros track the mixing, recycling, and mantle accretion in this peri-Gondwanic section from Precambrian to Devonian times.
{"title":"Alkaline Devonian magmatism of the Menorca Island: Tracking the mantle isotopic sources in the realm of the western Paleo-Tethys Ocean","authors":"","doi":"10.1016/j.chemgeo.2024.122362","DOIUrl":"10.1016/j.chemgeo.2024.122362","url":null,"abstract":"<div><p>Several locations with alkaline magmatism are recognised in Silurian-Devonian basins along the southern variscan autochthon units (e.g. Central Iberian Zone) of the northern Gondwana margin. The origin of the Devonian basins and their magmatism has not been studied in the context of the passive margin of Gondwana. The basement of Menorca, Balearic Islands, consists of a deep Devonian-Carboniferous basin with mafic igneous rocks, the Tramuntana Gabbros. In this study, we trace the geodynamic setting and isotopic sources of the Tramuntana Gabbros through elemental geochemistry, isotopic geochemistry (Sr<img>Nd) and U<img>Pb geochronology in zircons. These gabbros are the product of an intraplate alkaline magmatism with immobile trace element and REE contents similar to those of Ocean Island Basalts. Average <sup>87</sup>Sr/<sup>86</sup>Sr<sub>(370)</sub> of 0.708456 and εNd<sub>(370)</sub> of +4.0 indicate a source similar to a Type-2 enriched mantle with average T<sub>DM</sub> of 665 Ma, suggesting a relatively old metasomatized mantle. Concordant U<img>Pb ages of c. 597 Ma (Ediacaran, radiometric age) from a single population of 31 zircons separated from the Tramuntana Gabbros (Devonian, biostratigraphic age) reinforce the presence of older units in the corresponding lithospheric mantle. The Tramuntana Gabbros and the Devonian-Carboniferous sequences of Menorca limit the westward extension of the Paleo-Tethys Ocean, whose development never reached these westernmost regions. Assuming a common sublithospheric mantle source for the peri-Gondwanic Devonian alkaline rocks and considering the previous Cadomian (Neoproterozoic) subduction to be the most favourable origin of the separated zircons, the bulk rock T<sub>DM</sub> and zircon U<img>Pb data obtained from the Tramuntana Gabbros track the mixing, recycling, and mantle accretion in this peri-Gondwanic section from Precambrian to Devonian times.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S000925412400442X/pdfft?md5=80ca823fc3a1628ec9d6bf8e903b10bc&pid=1-s2.0-S000925412400442X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122361
Orogenic processes associated with the supercontinent cycle play crucial roles in the evolution of continental crust and surface environments. Detrital zircon records, useful archives of orogenic history, have recently suggested the possibility of orogenic quiescence during the Mesoproterozoic, the so-called Boring Billion. However, detrital zircon may not always provide a precise record of crustal evolution due to preservation bias. Detrital monazite, another beneficial accessory mineral, can provide key archives for a better understanding of the continental crust evolution over geological history. Here, we present the U–Pb ages, trace element abundances, and Nd isotope compositions of detrital monazites from four major rivers on the North and South American continents: the Mackenzie, Mississippi, Amazon, and Paraná rivers. The monazite U–Pb age data showed an uneven distribution, with peaks even during the Mesoproterozoic. The age distribution of the detrital monazites was broadly consistent with that of the detrital zircons in the same rivers. However, the two mineral's different occurrences and preservation potentials result in significant differences. The trace element and Nd isotope data of the detrital monazites indicate that the monazite U–Pb age peaks reflect the timing of the collision stage rather than the subduction stage. We further found cyclic secular variations in the detrital monazite Nd isotope compositions: their 143Nd/144Nd averages shifted from juvenile to reworked crustal signatures during the interval of supercontinent assembly, including the Proterozoic period. The Nd isotope shifts can be interpreted as crustal maturation through crustal re-melting and metamorphism driven by orogenic events. The monazite U–Pb age peaks and Nd isotope shift during the Mesoproterozoic suggest sustained crustal evolution rather than orogenic quiescence during the Boring Billion.
{"title":"Detrital monazite evidence for crustal evolution of the North and South American continents during the Boring Billion","authors":"","doi":"10.1016/j.chemgeo.2024.122361","DOIUrl":"10.1016/j.chemgeo.2024.122361","url":null,"abstract":"<div><p>Orogenic processes associated with the supercontinent cycle play crucial roles in the evolution of continental crust and surface environments. Detrital zircon records, useful archives of orogenic history, have recently suggested the possibility of orogenic quiescence during the Mesoproterozoic, the so-called <em>Boring Billion</em>. However, detrital zircon may not always provide a precise record of crustal evolution due to preservation bias. Detrital monazite, another beneficial accessory mineral, can provide key archives for a better understanding of the continental crust evolution over geological history. Here, we present the U–Pb ages, trace element abundances, and Nd isotope compositions of detrital monazites from four major rivers on the North and South American continents: the Mackenzie, Mississippi, Amazon, and Paraná rivers. The monazite U–Pb age data showed an uneven distribution, with peaks even during the Mesoproterozoic. The age distribution of the detrital monazites was broadly consistent with that of the detrital zircons in the same rivers. However, the two mineral's different occurrences and preservation potentials result in significant differences. The trace element and Nd isotope data of the detrital monazites indicate that the monazite U–Pb age peaks reflect the timing of the collision stage rather than the subduction stage. We further found cyclic secular variations in the detrital monazite Nd isotope compositions: their <sup>143</sup>Nd/<sup>144</sup>Nd averages shifted from juvenile to reworked crustal signatures during the interval of supercontinent assembly, including the Proterozoic period. The Nd isotope shifts can be interpreted as crustal maturation through crustal re-melting and metamorphism driven by orogenic events. The monazite U–Pb age peaks and Nd isotope shift during the Mesoproterozoic suggest sustained crustal evolution rather than orogenic quiescence during the Boring Billion.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009254124004418/pdfft?md5=11013467c4d29416f8d5ef895d39589c&pid=1-s2.0-S0009254124004418-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.1016/j.chemgeo.2024.122369
Arsenic (As)-rich groundwater poses a serious threat to human life and public environmental safety. In groundwater environments, iron–manganese minerals (FeMn minerals) are widely distributed and have outstanding adsorption and oxidation abilities for many toxic metal ions, making them important heavy metal scavengers. Exploring the application of Nature-based Solutions (NBS) to enhance the natural remediation of As-rich groundwater mediated by the mineralization of Fe and Mn is of great significance for promoting the stability of natural As reservoirs in groundwater. In this work, the effects of FeMn minerals and their related functional microorganisms on the migration and transformation of As in groundwater were reviewed, the interaction between components of FeMn minerals mediated by functional microorganisms on As immobilization process was revealed, the synergistic effect of Fe and Mn mineralization on the stabilization of As reservoir in groundwater was emphasized, and the potential biogeochemical cycles of Fe, Mn, and As mediated by functional microorganisms were analyzed. Based on bibliometric research, it is emphasized that FeMn minerals have a broad prospect in the field of treatment and remediation of As-rich groundwater, and the future prospects of enhancing the synergistic remediation of As-rich groundwater through Fe and Mn mineralization mediated by mixed microbial communities were proposed. In addition, in practical applications, the in-situ fixation of As in groundwater by FeMn minerals still faces technical challenges such as inhibiting the aggregation of As-fixing minerals and strengthening their durability. The results can provide new insights for a comprehensive and in-depth understanding of the synergistic enhancement for As reservoir stability in groundwater by Fe and Mn, as well as the natural remediation and scientific regulation of As-rich groundwater mediated by Fe and Mn mineralization.
{"title":"Collaborating iron and manganese for enhancing stability of natural arsenic sinks in groundwater: Current knowledge and future perspectives","authors":"","doi":"10.1016/j.chemgeo.2024.122369","DOIUrl":"10.1016/j.chemgeo.2024.122369","url":null,"abstract":"<div><p>Arsenic (As)-rich groundwater poses a serious threat to human life and public environmental safety. In groundwater environments, iron–manganese minerals (Fe<img>Mn minerals) are widely distributed and have outstanding adsorption and oxidation abilities for many toxic metal ions, making them important heavy metal scavengers. Exploring the application of Nature-based Solutions (NBS) to enhance the natural remediation of As-rich groundwater mediated by the mineralization of Fe and Mn is of great significance for promoting the stability of natural As reservoirs in groundwater. In this work, the effects of Fe<img>Mn minerals and their related functional microorganisms on the migration and transformation of As in groundwater were reviewed, the interaction between components of Fe<img>Mn minerals mediated by functional microorganisms on As immobilization process was revealed, the synergistic effect of Fe and Mn mineralization on the stabilization of As reservoir in groundwater was emphasized, and the potential biogeochemical cycles of Fe, Mn, and As mediated by functional microorganisms were analyzed. Based on bibliometric research, it is emphasized that Fe<img>Mn minerals have a broad prospect in the field of treatment and remediation of As-rich groundwater, and the future prospects of enhancing the synergistic remediation of As-rich groundwater through Fe and Mn mineralization mediated by mixed microbial communities were proposed. In addition, in practical applications, the in-situ fixation of As in groundwater by Fe<img>Mn minerals still faces technical challenges such as inhibiting the aggregation of As-fixing minerals and strengthening their durability. The results can provide new insights for a comprehensive and in-depth understanding of the synergistic enhancement for As reservoir stability in groundwater by Fe and Mn, as well as the natural remediation and scientific regulation of As-rich groundwater mediated by Fe and Mn mineralization.</p></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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