Pub Date : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106254
Michal Šujan , Kishan Aherwar , Katarína Šarinová , Tomáš Vlček , Andrej Chyba , Natália Hudáčková , Michal Jamrich , Marianna Kováčová , AsterTeam , Orsolya Sztanó
The authigenic 10Be/9Be dating method is a relatively new geochronological technique that shows great potential for use in epicontinental sedimentary successions, largely due to its ability to date ubiquitous mud. However, the factors influencing the applicability of this method are not yet fully understood, which limits its robust application. This study presents the first direct evidence that deep-water mud redeposition can lead to significantly older authigenic 10Be/9Be ages, with an offset of ca. 2 Myr in the studied example. The redeposition generated hybrid event beds (products of mixed gravity flows) on the Late Miocene basin floor of Lake Pannon. The source material for redeposition was the Middle Miocene successions exposed on the lake bottom, as indicated by reworked foraminiferal and calcareous nannoplankton fossils, as well as inorganic and organic geochemical proxies. This case study suggests that a thorough understanding of depositional processes and paleogeographic settings is essential when proposing future authigenic 10Be/9Be dating sampling strategies, to avoid the influence of deep-water mud redeposition by hybrid event beds. Additionally, a notable shift in geochemical signature was observed between syn- and post-rift phases. During the ca. 6 Myr-long rifting, sediment recycling and local provenance were dominant from the rifted basin margins, while the post-rift stage marked the onset of a regional-scale sediment routing system. Notably, organic matter preserved its compositional signature of the redeposited successions.
{"title":"Hindering the applicability of the authigenic 10Be/9Be dating by redeposition of mud in hybrid event beds, eastern Danube Basin, Slovakia","authors":"Michal Šujan , Kishan Aherwar , Katarína Šarinová , Tomáš Vlček , Andrej Chyba , Natália Hudáčková , Michal Jamrich , Marianna Kováčová , AsterTeam , Orsolya Sztanó","doi":"10.1016/j.apgeochem.2024.106254","DOIUrl":"10.1016/j.apgeochem.2024.106254","url":null,"abstract":"<div><div>The authigenic <sup>10</sup>Be/<sup>9</sup>Be dating method is a relatively new geochronological technique that shows great potential for use in epicontinental sedimentary successions, largely due to its ability to date ubiquitous mud. However, the factors influencing the applicability of this method are not yet fully understood, which limits its robust application. This study presents the first direct evidence that deep-water mud redeposition can lead to significantly older authigenic <sup>10</sup>Be/<sup>9</sup>Be ages, with an offset of ca. 2 Myr in the studied example. The redeposition generated hybrid event beds (products of mixed gravity flows) on the Late Miocene basin floor of Lake Pannon. The source material for redeposition was the Middle Miocene successions exposed on the lake bottom, as indicated by reworked foraminiferal and calcareous nannoplankton fossils, as well as inorganic and organic geochemical proxies. This case study suggests that a thorough understanding of depositional processes and paleogeographic settings is essential when proposing future authigenic <sup>10</sup>Be/<sup>9</sup>Be dating sampling strategies, to avoid the influence of deep-water mud redeposition by hybrid event beds. Additionally, a notable shift in geochemical signature was observed between syn- and post-rift phases. During the ca. 6 Myr-long rifting, sediment recycling and local provenance were dominant from the rifted basin margins, while the post-rift stage marked the onset of a regional-scale sediment routing system. Notably, organic matter preserved its compositional signature of the redeposited successions.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106254"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106261
Yang Ding , Zhenqing Shi
Organic matter retained by reactive minerals constitutes an essential mechanism for long-term storage of carbon in soil, a process that is governed by climate factors. However, how the reactive mineral-associated organic matter affects the composition of soil dissolved organic matter (DOM) across a broad range of climates remains unclear. In this study, the contents of reactive minerals and their associated organic matter were determined by the chemical extraction method. Moreover, the effects of organic matter retained by reactive minerals on soil DOM composition were investigated at molecular level across a wide environmental gradient, by employing Fourier transform ion cyclotron resonance mass spectrometry, solid-state 13C nuclear magnetic resonance and statistical analyses. The results of FT-ICR-MS and correlation analyses indicated that the relative abundances of carbohydrates and proteins/amino sugars decreased, while the relative abundance of condensed aromatics increased with the increase of the content of organic matter retained by reactive minerals per unit mass (i.e., (OC)RN) in soils. We highlighted that the adsorption and dissolution processes of DOM molecules, especially aromatic molecules, on reactive minerals played crucial roles in regulating the molecular composition of DOM in soil solution. Furthermore, (OC)RN was controlled by climate-driven chemical weathering (e.g., precipitation). Our results imply that (OC)RN is a key variable for regulating soil DOM composition under the impacts of climates, and can be used in developing prediction models for carbon cycling.
{"title":"The molecular composition of soil dissolved organic matter regulated by reactive mineral-associated organic matter under a broad range of climates","authors":"Yang Ding , Zhenqing Shi","doi":"10.1016/j.apgeochem.2024.106261","DOIUrl":"10.1016/j.apgeochem.2024.106261","url":null,"abstract":"<div><div>Organic matter retained by reactive minerals constitutes an essential mechanism for long-term storage of carbon in soil, a process that is governed by climate factors. However, how the reactive mineral-associated organic matter affects the composition of soil dissolved organic matter (DOM) across a broad range of climates remains unclear. In this study, the contents of reactive minerals and their associated organic matter were determined by the chemical extraction method. Moreover, the effects of organic matter retained by reactive minerals on soil DOM composition were investigated at molecular level across a wide environmental gradient, by employing Fourier transform ion cyclotron resonance mass spectrometry, solid-state <sup>13</sup>C nuclear magnetic resonance and statistical analyses. The results of FT-ICR-MS and correlation analyses indicated that the relative abundances of carbohydrates and proteins/amino sugars decreased, while the relative abundance of condensed aromatics increased with the increase of the content of organic matter retained by reactive minerals per unit mass (i.e., (OC)<sub>RN</sub>) in soils. We highlighted that the adsorption and dissolution processes of DOM molecules, especially aromatic molecules, on reactive minerals played crucial roles in regulating the molecular composition of DOM in soil solution. Furthermore, (OC)<sub>RN</sub> was controlled by climate-driven chemical weathering (e.g., precipitation). Our results imply that (OC)<sub>RN</sub> is a key variable for regulating soil DOM composition under the impacts of climates, and can be used in developing prediction models for carbon cycling.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106261"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Presented are results of field study of dissolved 137Cs seasonal variations in two ponds of the close vicinity of the Fukushima Daiichi nuclear plant contaminated after the accident in March 2011. Two mechanisms were investigated which can possibly explain regular seasonal variations of dissolved 137Cs concentrations in ponds: temperature dependence of 137Cs desorption from sediments to solution, and ion-exchange remobilization of 137Cs by cations of ammonium generated by decomposition of organic matter. A process-level model of dissolved 137Cs seasonal variations accounting for these two mechanisms was proposed and a correspondent equation describing 137Cs seasonality was suggested. The activation energy of 137Cs desorption from sediments for the two ponds is close to each other, being 30 kJ/mol and 24.6 kJ/mol and close to those obtained in laboratory experiments. Unlike Fukushima rivers, shallow and fast flowing, and hence with negligible ammonium concentration, in the stagnated waters of the studied ponds the role of ammonium in 137Cs mobilization seems to be comparable with that of water temperature, or even be prevalent.
{"title":"Experimental field study of basic mechanisms underlying dissolved 137Cs seasonal variations in ponds heavily contaminated after the Fukushima Daiichi nuclear power plant accident","authors":"Alexei Konoplev , Honoka Kurosawa , Yoshifumi Wakiyama , Yasunori Igarashi , Volodymyr Kanivets , Kenji Nanba","doi":"10.1016/j.apgeochem.2024.106250","DOIUrl":"10.1016/j.apgeochem.2024.106250","url":null,"abstract":"<div><div>Presented are results of field study of dissolved <sup>137</sup>Cs seasonal variations in two ponds of the close vicinity of the Fukushima Daiichi nuclear plant contaminated after the accident in March 2011. Two mechanisms were investigated which can possibly explain regular seasonal variations of dissolved <sup>137</sup>Cs concentrations in ponds: temperature dependence of <sup>137</sup>Cs desorption from sediments to solution, and ion-exchange remobilization of <sup>137</sup>Cs by cations of ammonium generated by decomposition of organic matter. A process-level model of dissolved <sup>137</sup>Cs seasonal variations accounting for these two mechanisms was proposed and a correspondent equation describing <sup>137</sup>Cs seasonality was suggested. The activation energy of <sup>137</sup>Cs desorption from sediments for the two ponds is close to each other, being 30 kJ/mol and 24.6 kJ/mol and close to those obtained in laboratory experiments. Unlike Fukushima rivers, shallow and fast flowing, and hence with negligible ammonium concentration, in the stagnated waters of the studied ponds the role of ammonium in <sup>137</sup>Cs mobilization seems to be comparable with that of water temperature, or even be prevalent.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106250"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mobilization of uranium in granite-related systems presents a complex interplay of chemical and hydrodynamic factors. This is particularly obvious within syn-orogenic detachment zones where per descensum surface-derived fluids interact with per ascensum deeply sourced hydrothermal fluids. In this study, we employ a thermo-hydro-chemical (TH-C) modeling approach to explore the multifaceted processes that govern uranium transport and deposition in such environments. Our findings indicate that uranium mobility is not solely determined by the oxidizing nature of the percolating surface-derived fluids. Actually, the oxidation-reduction potential of these fluids varies as they flow in the crust, ultimately adjusting towards more neutral or mildly reducing conditions conducive to uranium dissolution and precipitation. Even in the presence of magnetite, which enhances the reductive potential of the fluids, uranium continues to dissolve, albeit in much smaller quantities, with U(IV) being the predominant species in the aqueous phase. The study highlights the crucial roles of temperature, pH, and fluid/rock interaction ratios in influencing uranium leaching efficacy. High fluid/rock ratios enhance uranium extraction from source rocks. A fluid/rock ratio around 1 is optimal, maximizing the dissolution of uranium-bearing minerals in the source rock and promoting the precipitation of uranium minerals in different locations along the fluid pathway due to changes in fluid chemistry. The TH-C modeling has the potential to be applied to a variety of other uranium deposits, developed below 300 °C.
{"title":"Fluid-rock reaction path modeling of uranium mobility in granite-related mineralization: A case study from the Variscan South Armorican Domain","authors":"Khaled Bock , Yannick Branquet , Olivier Pourret , Philippe Boulvais","doi":"10.1016/j.apgeochem.2024.106241","DOIUrl":"10.1016/j.apgeochem.2024.106241","url":null,"abstract":"<div><div>The mobilization of uranium in granite-related systems presents a complex interplay of chemical and hydrodynamic factors. This is particularly obvious within syn-orogenic detachment zones where <em>per descensum</em> surface-derived fluids interact with <em>per ascensum</em> deeply sourced hydrothermal fluids. In this study, we employ a thermo-hydro-chemical (TH-C) modeling approach to explore the multifaceted processes that govern uranium transport and deposition in such environments. Our findings indicate that uranium mobility is not solely determined by the oxidizing nature of the percolating surface-derived fluids. Actually, the oxidation-reduction potential of these fluids varies as they flow in the crust, ultimately adjusting towards more neutral or mildly reducing conditions conducive to uranium dissolution and precipitation. Even in the presence of magnetite, which enhances the reductive potential of the fluids, uranium continues to dissolve, albeit in much smaller quantities, with U(IV) being the predominant species in the aqueous phase. The study highlights the crucial roles of temperature, pH, and fluid/rock interaction ratios in influencing uranium leaching efficacy. High fluid/rock ratios enhance uranium extraction from source rocks. A fluid/rock ratio around 1 is optimal, maximizing the dissolution of uranium-bearing minerals in the source rock and promoting the precipitation of uranium minerals in different locations along the fluid pathway due to changes in fluid chemistry. The TH-C modeling has the potential to be applied to a variety of other uranium deposits, developed below 300 °C.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106241"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106270
Cyril Aumar , Hélène Celle , Mélanie Quenet , Olivier Voldoire , Elisabeth Allain , Alexandre Garreau , Nicolas Caillon , Pierre Nevers , Jean-Luc Devidal , Gilles Mailhot , Aude Beauger
The continental hydrosystems of wetlands play fundamental socio-economic and environmental roles in all aquatic environments. These ecosystems, when located at the interface between surface and groundwater, such as oxbows, are of crucial importance in regulating water and nutrient flows. They help control water quality and provide ideal habitats for often fragile species. The transfer of contaminants into the different compartments of the groundwater-wetland-river continuum is difficult to characterize because they are most often of different types and origins within the same hydrosystem. The objective of this study is to characterize water quality and water exchange using a multi-tracer approach combining monthly hydrochemical monitoring, isotopic characterization of NO3− molecules (δ18ONO3 and δ15NNO3) and concentration of chemical micropollutant particles. This methodology is applied to a fluvial annex of the Allier River, the Auzon oxbow hydrosystem, subject to moderate environmental and anthropogenic pressure (low level of industrialization and urbanization, mixed conventional farming). Nitrate (NO3−) and phosphate (PO43−) concentrations do not behave in the same way over time: NO3− has a seasonal dynamic, whereas phosphates are disconnected from the hydrological regime. Some subsystems of the Auzon oxbow are undergoing denitrification, demonstrating the importance of preserving these environments for their nutrient regulation potential. As for chemical micropollutants and PO43−, the low overall concentration of these two contaminants, coupled with the high dilution potential of the Auzon oxbow hydrosystem, means that average concentrations remain within acceptable standards for surface waters. Based on these results, the Auzon hydrosystem is maintaining good ecological quality despite nutrient flows from multiple sources. The multi-tracer approach used in this study demonstrates its effectiveness in determining the origin of nutrients, and it could be applied to other studies in contexts where environmental and societal pressures are significantly higher.
{"title":"Sources and fates of NO3− and PO43− in an alluvial plain wetland - Insights from the Auzon oxbow and the alluvial aquifer of the Allier (Auvergne, France)","authors":"Cyril Aumar , Hélène Celle , Mélanie Quenet , Olivier Voldoire , Elisabeth Allain , Alexandre Garreau , Nicolas Caillon , Pierre Nevers , Jean-Luc Devidal , Gilles Mailhot , Aude Beauger","doi":"10.1016/j.apgeochem.2024.106270","DOIUrl":"10.1016/j.apgeochem.2024.106270","url":null,"abstract":"<div><div>The continental hydrosystems of wetlands play fundamental socio-economic and environmental roles in all aquatic environments. These ecosystems, when located at the interface between surface and groundwater, such as oxbows, are of crucial importance in regulating water and nutrient flows. They help control water quality and provide ideal habitats for often fragile species. The transfer of contaminants into the different compartments of the groundwater-wetland-river continuum is difficult to characterize because they are most often of different types and origins within the same hydrosystem. The objective of this study is to characterize water quality and water exchange using a multi-tracer approach combining monthly hydrochemical monitoring, isotopic characterization of NO<sub>3</sub><sup>−</sup> molecules (δ<sup>18</sup>O<sub>NO3</sub> and δ<sup>15</sup>N<sub>NO3</sub>) and concentration of chemical micropollutant particles. This methodology is applied to a fluvial annex of the Allier River, the Auzon oxbow hydrosystem, subject to moderate environmental and anthropogenic pressure (low level of industrialization and urbanization, mixed conventional farming). Nitrate (NO<sub>3</sub><sup>−</sup>) and phosphate (PO<sub>4</sub><sup>3−</sup>) concentrations do not behave in the same way over time: NO<sub>3</sub><sup>−</sup> has a seasonal dynamic, whereas phosphates are disconnected from the hydrological regime. Some subsystems of the Auzon oxbow are undergoing denitrification, demonstrating the importance of preserving these environments for their nutrient regulation potential. As for chemical micropollutants and PO<sub>4</sub><sup>3−</sup>, the low overall concentration of these two contaminants, coupled with the high dilution potential of the Auzon oxbow hydrosystem, means that average concentrations remain within acceptable standards for surface waters. Based on these results, the Auzon hydrosystem is maintaining good ecological quality despite nutrient flows from multiple sources. The multi-tracer approach used in this study demonstrates its effectiveness in determining the origin of nutrients, and it could be applied to other studies in contexts where environmental and societal pressures are significantly higher.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106270"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106259
Dogo Lawrence Aleku , Harald Biester , Thomas Pichler
Between 1965 and 2017, the Port Harcourt Refining Company (PHRC) refined crude oil in the eastern Niger Delta and groundwater hydrocarbon contamination in the area is known. However, nothing is known about the concentration, source, speciation and mobility of mercury (Hg), a potential byproduct of oil refining. To address this, groundwater samples were collected along the wastewater discharge outlet (WDO) and around the PHRC. The Hg concentrations in groundwater near the WDO varied between 0.2 and 6 μg/L, compared to less than 0.01 μg/L at distances greater than 300 m from the WDO and reference sites away from the refinery. Up to 63 % of Hg were present as Hg bound to particles larger than 0.45 μm (Hgpart), suggesting the prevalence of Hg transport in the suspended colloidal phase in the aquifer. Operational-defined Hg speciation shows that 33 % of the total Hg (THg) occurred as inorganic, reactive Hg2+. In comparison, only 4 % occurred as dissolved organic matter-bound Hg2+ despite high DOC and BTEX concentrations of up to 47 mg/L and 2888 μg/L, respectively. Notably, the DOC is predominantly petroleum hydrocarbon, generated from the ongoing oil and gas activities at the site. This suggests that hydrocarbon-based-DOC does not bind Hg.
Sediment samples collected from the wastewater discharge point (WDP) contained Hg concentrations of up to 529 μg/kg, and the carbon (C) content reached 40 %. Sediment batch leaching experiments showed that up to 23.5 % of the Hg in the quartz-dominant sediment can be mobilized into groundwater under oxic conditions. Despite the presence of petroleum hydrocarbon, Hg retention was significantly controlled by the sediment's natural organic matter (NOM). Hence, the discharged oil and gas production wastewater due to crude oil refining released Hg into the aquifer, where NOM ultimately controls fate and transport.
{"title":"Elevated mercury (Hg) in groundwater caused by oil and gas production","authors":"Dogo Lawrence Aleku , Harald Biester , Thomas Pichler","doi":"10.1016/j.apgeochem.2024.106259","DOIUrl":"10.1016/j.apgeochem.2024.106259","url":null,"abstract":"<div><div>Between 1965 and 2017, the Port Harcourt Refining Company (PHRC) refined crude oil in the eastern Niger Delta and groundwater hydrocarbon contamination in the area is known. However, nothing is known about the concentration, source, speciation and mobility of mercury (Hg), a potential byproduct of oil refining. To address this, groundwater samples were collected along the wastewater discharge outlet (WDO) and around the PHRC. The Hg concentrations in groundwater near the WDO varied between 0.2 and 6 μg/L, compared to less than 0.01 μg/L at distances greater than 300 m from the WDO and reference sites away from the refinery. Up to 63 % of Hg were present as Hg bound to particles larger than 0.45 μm (Hg<sub>part</sub>), suggesting the prevalence of Hg transport in the suspended colloidal phase in the aquifer. Operational-defined Hg speciation shows that 33 % of the total Hg (THg) occurred as inorganic, reactive Hg<sup>2+</sup>. In comparison, only 4 % occurred as dissolved organic matter-bound Hg<sup>2+</sup> despite high DOC and BTEX concentrations of up to 47 mg/L and 2888 μg/L, respectively. Notably, the DOC is predominantly petroleum hydrocarbon, generated from the ongoing oil and gas activities at the site. This suggests that hydrocarbon-based-DOC does not bind Hg.</div><div>Sediment samples collected from the wastewater discharge point (WDP) contained Hg concentrations of up to 529 μg/kg, and the carbon (C) content reached 40 %. Sediment batch leaching experiments showed that up to 23.5 % of the Hg in the quartz-dominant sediment can be mobilized into groundwater under oxic conditions. Despite the presence of petroleum hydrocarbon, Hg retention was significantly controlled by the sediment's natural organic matter (NOM). Hence, the discharged oil and gas production wastewater due to crude oil refining released Hg into the aquifer, where NOM ultimately controls fate and transport.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106259"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106258
Héctor Zúñiga-Barra , Edgar Velastegui , Javiera Toledo-Alarcón , Lorena Jorquera , Mariella Rivas , David Jeison
Recent research has suggested the applicability of microbially induced calcite precipitation (MICP) to improve wind erosion resistance across diverse media, from clay to sandy soils. While various factors influencing MICP performance have been investigated, comprehensive studies considering the synergistic interactions between biocementation media composition, dosages, available urease activity, and urea-calcium ratios are limited. Consequently, identifying key factors governing MICP during tailings biocementation remains crucial for optimizing treatment strategies. This is specially the case for MICP application for mine tailings biocementation, due to the limited available research dealing with this substrate. This research studied the effect of several factors, when biocementing mine tailings, using a factorial design. The results confirm the key role of the biocementation media dosage and the urea-calcium ratio, and their synergistic interaction during biocementation of tailings, as they determine the calcium and inorganic carbon available to produce calcium precipitates. Biocementation of tailings by applying MICP substantially improved surface strength, leading to a drastic reduction in wind erosion resistance. These results confirm the potential of MICP to become an interesting tool to reduce windblown dust emissions from tailings deposits.
{"title":"Investigation of the key factors favouring the biocementing effect of microbially induced calcite precipitation when applied to mine tailings","authors":"Héctor Zúñiga-Barra , Edgar Velastegui , Javiera Toledo-Alarcón , Lorena Jorquera , Mariella Rivas , David Jeison","doi":"10.1016/j.apgeochem.2024.106258","DOIUrl":"10.1016/j.apgeochem.2024.106258","url":null,"abstract":"<div><div>Recent research has suggested the applicability of microbially induced calcite precipitation (MICP) to improve wind erosion resistance across diverse media, from clay to sandy soils. While various factors influencing MICP performance have been investigated, comprehensive studies considering the synergistic interactions between biocementation media composition, dosages, available urease activity, and urea-calcium ratios are limited. Consequently, identifying key factors governing MICP during tailings biocementation remains crucial for optimizing treatment strategies. This is specially the case for MICP application for mine tailings biocementation, due to the limited available research dealing with this substrate. This research studied the effect of several factors, when biocementing mine tailings, using a factorial design. The results confirm the key role of the biocementation media dosage and the urea-calcium ratio, and their synergistic interaction during biocementation of tailings, as they determine the calcium and inorganic carbon available to produce calcium precipitates. Biocementation of tailings by applying MICP substantially improved surface strength, leading to a drastic reduction in wind erosion resistance. These results confirm the potential of MICP to become an interesting tool to reduce windblown dust emissions from tailings deposits.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"179 ","pages":"Article 106258"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106217
Angus G. Campbell , Ian Cartwright , John A. Webb , Dioni I. Cendón , Matthew J. Currell
Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia's Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable 3H (0.43 TU), and activities of radiocarbon a14C (14.1 – 95.3 pMC) and chlorine-36 R36Cl (78.1 × 10−15 – 161 × 10−15) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO3 and F concentrations and heavy fraction hydrocarbons (>100 μg/L C10–C40) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine's groundwater impacts, which was the basis of the mine's approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.
{"title":"Using geochemical and geophysical data to characterise inter-aquifer connectivity and impacts on shallow aquifers and groundwater dependent ecosystems","authors":"Angus G. Campbell , Ian Cartwright , John A. Webb , Dioni I. Cendón , Matthew J. Currell","doi":"10.1016/j.apgeochem.2024.106217","DOIUrl":"10.1016/j.apgeochem.2024.106217","url":null,"abstract":"<div><div>Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia's Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable <sup>3</sup>H (0.43 TU), and activities of radiocarbon a<sup>14</sup>C (14.1 – 95.3 pMC) and chlorine-36 R<sup>36</sup>Cl (78.1 × 10<sup>−15</sup> – 161 × 10<sup>−15</sup>) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO<sub>3</sub> and F concentrations and heavy fraction hydrocarbons (>100 μg/L C<sub>10</sub>–C<sub>40</sub>) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine's groundwater impacts, which was the basis of the mine's approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106217"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106219
Falko Vehling , Georg Kosakowski , Haibing Shao
Deep geological disposal is a widely proposed approach for safe storage of low- and intermediate-level radioactive waste (L/ILW) for tens to hundreds of thousands of years. Although the use of cement materials will maintain a high pH environment that is favorable for radionuclide retention, slows down metal corrosion, and suppresses microbial activity, different gases may still be produced by chemical reactions, such as pH-dependent anoxic corrosion of metals, and the degradation of organic matter as well. Both reactions consume water and may lead to the formation of a free gas phase within and around the repository.
In order to investigate the controlling factors of this gas production processes, a coupled reactive transport model of component-based two-phase flow in the OpenGeoSys framework is adopted here. Building on the previous work by Huang et al. (2021), this work extends the geometric configuration of the model from a single drum to the scale of a waste container (12 drums) in order to more realistically model the water and gas fluxes. The geochemical evolution of a container filled with cemented steel drums and surrounded by mortar and host rock is simulated in a two-dimensional setup over 500 years. The relative humidity in the pore space as measure of water availability determines the chemical reactivity.
We have conducted a sensitivity study for the influence of mortar capillarity and permeability on gas production over time in the waste drums. As expected, the amount of gas produced within the first several years depends primarily on the initial water content within the waste drum and the amount of fast degradable waste stored in a drum. Later, this feedback system is forced into a new equilibrium, where the water transport has to match the water consumption rate at the waste package. Both, the mortar capillarity and permeability control the point in time when the equilibrium is reached and the subsequent rate of gas production.
This study shows how reactive transport models are capable to help with the understanding of couplings between chemical and transport processes that control gas generation in L/ILW waste repositories, especially in barrier systems with different material properties. Future studies could benefit from more accurate parameterization of the chemical reactions, depending on the availability of new experimental data and/or more realistic process-based model approaches.
{"title":"Two-phase reactive transport modeling of heterogeneous gas production in a low- and intermediate-level radioactive waste repository","authors":"Falko Vehling , Georg Kosakowski , Haibing Shao","doi":"10.1016/j.apgeochem.2024.106219","DOIUrl":"10.1016/j.apgeochem.2024.106219","url":null,"abstract":"<div><div>Deep geological disposal is a widely proposed approach for safe storage of low- and intermediate-level radioactive waste (L/ILW) for tens to hundreds of thousands of years. Although the use of cement materials will maintain a high pH environment that is favorable for radionuclide retention, slows down metal corrosion, and suppresses microbial activity, different gases may still be produced by chemical reactions, such as pH-dependent anoxic corrosion of metals, and the degradation of organic matter as well. Both reactions consume water and may lead to the formation of a free gas phase within and around the repository.</div><div>In order to investigate the controlling factors of this gas production processes, a coupled reactive transport model of component-based two-phase flow in the OpenGeoSys framework is adopted here. Building on the previous work by Huang et al. (2021), this work extends the geometric configuration of the model from a single drum to the scale of a waste container (12 drums) in order to more realistically model the water and gas fluxes. The geochemical evolution of a container filled with cemented steel drums and surrounded by mortar and host rock is simulated in a two-dimensional setup over 500 years. The relative humidity in the pore space as measure of water availability determines the chemical reactivity.</div><div>We have conducted a sensitivity study for the influence of mortar capillarity and permeability on gas production over time in the waste drums. As expected, the amount of gas produced within the first several years depends primarily on the initial water content within the waste drum and the amount of fast degradable waste stored in a drum. Later, this feedback system is forced into a new equilibrium, where the water transport has to match the water consumption rate at the waste package. Both, the mortar capillarity and permeability control the point in time when the equilibrium is reached and the subsequent rate of gas production.</div><div>This study shows how reactive transport models are capable to help with the understanding of couplings between chemical and transport processes that control gas generation in L/ILW waste repositories, especially in barrier systems with different material properties. Future studies could benefit from more accurate parameterization of the chemical reactions, depending on the availability of new experimental data and/or more realistic process-based model approaches.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106219"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-01-01DOI: 10.1016/j.apgeochem.2024.106249
Mengzi Zhou , Xiancai Lu , Meng Chen , Qin Li , Kai Wang , Xiandong Liu
A key issue about radioactive waste disposal and nuclear accident contamination control is the retention of radionuclides in clay minerals. The cation (Cs+, Rb+, Na+, K+) selectivity in montmorillonite (Mt) interlayers have not been quantitatively studied. This work employs classical molecular dynamics (CMD) to systematically investigate the interlayer structure, swelling properties, diffusion dynamics, and cation exchange processes. The selectivity of alkali ions within the interlayer space coupled with clay swelling/collapse under different water activity (aw) and cation activity, has been quantified. Both Cs-, Rb–Mt demonstrate a monolayer hydrate configuration as the most stable state. The mobility of intercalated species, as indicated by self-diffusion coefficients, exhibits a stepwise trend with increasing water content. The cationic selectivity within the interlayer follows the order Cs+ > Rb+ > K+ > Na + at aw = 1.0. The logarithm values of the selectivity coefficients for Cs/Rb relative to Na/K are as follows: logKc(Cs/K) = 0.73, logKc(Cs/Na) = 1.62, logKc(Rb/K) = 0.62, and logKc(Rb/Na) = 1.57 at aw = 1.0. A model correlating selectivity coefficients with water activity has been proposed. It is noted that Cs+ and Rb+ ions tend to accumulate within the interlayer as water activity decreases, and interlayer Rb+ competes with Cs+ for exchange positions at low water activity. These results can be used to quantify cationic partitioning during the remediation of radiocesium contamination in soil and weathering processes of sediments.
{"title":"Molecular simulation on Cs, Rb retention in Na/K-montmorillonite interlayer coupling clay swelling/collapse","authors":"Mengzi Zhou , Xiancai Lu , Meng Chen , Qin Li , Kai Wang , Xiandong Liu","doi":"10.1016/j.apgeochem.2024.106249","DOIUrl":"10.1016/j.apgeochem.2024.106249","url":null,"abstract":"<div><div>A key issue about radioactive waste disposal and nuclear accident contamination control is the retention of radionuclides in clay minerals. The cation (Cs<sup>+</sup>, Rb<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup>) selectivity in montmorillonite (Mt) interlayers have not been quantitatively studied. This work employs classical molecular dynamics (CMD) to systematically investigate the interlayer structure, swelling properties, diffusion dynamics, and cation exchange processes. The selectivity of alkali ions within the interlayer space coupled with clay swelling/collapse under different water activity (<em>a</em><sub>w</sub>) and cation activity, has been quantified. Both Cs-, Rb–Mt demonstrate a monolayer hydrate configuration as the most stable state. The mobility of intercalated species, as indicated by self-diffusion coefficients, exhibits a stepwise trend with increasing water content. The cationic selectivity within the interlayer follows the order Cs<sup>+</sup> > Rb<sup>+</sup> > K<sup>+</sup> > Na <sup>+</sup> at <em>a</em><sub>w</sub> = 1.0. The logarithm values of the selectivity coefficients for Cs/Rb relative to Na/K are as follows: log<em>K</em><sub><em>c</em></sub>(Cs/K) = 0.73, log<em>K</em><sub><em>c</em></sub>(Cs/Na) = 1.62, log<em>K</em><sub><em>c</em></sub>(Rb/K) = 0.62, and log<em>K</em><sub><em>c</em></sub>(Rb/Na) = 1.57 at <em>a</em><sub>w</sub> = 1.0. A model correlating selectivity coefficients with water activity has been proposed. It is noted that Cs<sup>+</sup> and Rb<sup>+</sup> ions tend to accumulate within the interlayer as water activity decreases, and interlayer Rb<sup>+</sup> competes with Cs<sup>+</sup> for exchange positions at low water activity. These results can be used to quantify cationic partitioning during the remediation of radiocesium contamination in soil and weathering processes of sediments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"178 ","pages":"Article 106249"},"PeriodicalIF":3.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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