Applied Geochemistry最新文献

{"title":"A systematic comparison of pore water sampling methods in flooded soils: Element-specific biases in inorganic contaminants due to oxidation and filtration artefacts","authors":"F. Xavier Dengra i Grau ,&nbsp;Liesbeth Van Laer ,&nbsp;Erik Smolders","doi":"10.1016/j.apgeochem.2025.106508","DOIUrl":"10.1016/j.apgeochem.2025.106508","url":null,"abstract":"<div><div>Flooding of contaminated soils affects the mobility and bioavailability of inorganic contaminants. Accurately identifying these changes requires pore water sampling methods with minimal artefacts due to oxidation or exclusion of mobile colloids. This study was set up to identify such artefacts by comparison of the solution composition among different three pore water sampling methods as a function of the soil redox potential E_h, i.e., Diffusion Equilibrium of Thin Films (DET), rhizons (suction cups), and soil centrifugates, followed by filtration. The first two methods were applied to intact flooded soil, whereas the latter was applied to destructively sampled soil aliquots. The soil (pH 6.7, 8.9 % organic carbon), a candidate for wetland construction, was sampled in a natural grassland as intact 35 cm cores of unsaturated soil. The soil columns were flooded, and pore water was sampled at various depths (6–20 cm) and times after flooding (3–100 days), representing samples with E_h between +450 mV and −240 mV. The pore waters sampled by the rhizons confirmed well-known contrasting trends between elements that are mobilized (Fe, U) or immobilised (Cd, Zn) upon reduction. Pore water compositions were similar among the three methods for redox-insensitive elements, mainly occurring as free ions such as Na, K, Ca, Mg and Ba. In contrast, strong deviations were found for redox-sensitive elements. The sampling bias, expressed as the ratio of pore water concentrations in the centrifuged samples to those in the rhizon, drifted from close to 1 at three days of waterlogging (no bias) to 0.01 (Fe), 0.17 (U) and 0.08 in (P) after 100 days. Conversely, opposite trends were found with ratios of Cd (82), Zn (20) and SO₄²⁻ (18). All of this suggests oxidation artefacts during centrifugation. The DET oversampled Fe compared to rhizons due to oxidation and precipitation of Fe in the DET, which created an adsorptive sink, particularly for post-transition metals and P and, hence, oversampled several mobile elements in reduced conditions. The sampling bias (DET/rhizon) was factor 4 for Fe (geomean ratio) but peaked up to 390 for P and 1300 for Pb, which may be related to higher exclusion of colloids by the rhizons, that had the smallest pore size of the filters. Overall, rhizon samplers showed superior performance in capturing redox-induced changes, but may underestimate in-situ mobility of Pb. No single pore water sampling method can unequivocally detect the mobility changes for all elements or species in reduced conditions: a weight of evidence of different methods is generally recommended.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106508"},"PeriodicalIF":3.4,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750523","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}

{"title":"Quantifying formations and contributions to boron enrichment in a hot spring-river-salt lake system in the Qaidam Basin: Insights from boron isotopes and geochemical proxies","authors":"Wenjie Zhang ,&nbsp;Daoming Cai ,&nbsp;Yanfei Zhang ,&nbsp;Zhihua Zhang ,&nbsp;Ke Jin","doi":"10.1016/j.apgeochem.2025.106507","DOIUrl":"10.1016/j.apgeochem.2025.106507","url":null,"abstract":"<div><div>The northern margin of the East Kunlun Mountains is a distinctive basin and range transition zone characterized by diverse landforms and abundant salt resources. Within this region, the Nalenggele River Catchment is particularly notable for its rich supergene boron deposits and complete hydrological systems including hot springs, rivers, and salt lakes. This region serves as an ideal natural laboratory for studying the boron behavior during regional chemical weathering and migration processes, as well as for understanding boron ore-forming mechanisms in arid basins with alpine-cold environment. However, the sources of dissolved boron in the river and lake waters are still controversial. The relative hydrological and hydrochemical processes have not been quantitatively researched, hindering a comprehensive understanding of boron enriching processes. In this study, the geochemical compositions and boron isotopes of river waters and rock samples in the Nalenggele River Catchment were systematically analysed to understand the formation processes of dissolved boron in rivers and to quantify potential contributions. The results showed: (1) Chemical weathering plays an important role in the formation of dissolved boron in low-boron rivers (&lt;1 mg/L), whereas the enriched boron in high-boron rivers is mainly derived from geothermal waters in the source areas. (2) Geothermal water inputs account for 86.2 % ∼ 91.4 % of dissolved boron and lithium in the Hongshui River, a tributary of the Nalenggele River. During the tributary confluence, over 70 % of dissolved boron in the Nalenggele River is contributed by the Hongshui River. (3) Boron isotopes in water are effective for source identification but less reliable for quantitative assessment of boron enrichment processes in the Nalenggele River Catchment due to its fractionation-prone property. This study presents quantitative results of boron sources, contributions, and accumulations and gives an insight into constraints of boron isotope as a geochemical signature. It is expected to provide an enhanced understandings of boron migration, enrichment, and ore-forming processes within “hot spring - river - salt lake” systems of the Tibetan Plateau.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106507"},"PeriodicalIF":3.4,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724731","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}

{"title":"Influence of weathering-driven mineralogical evolution on phosphorite dissolution behavior","authors":"Bing Liu ,&nbsp;Caixiang Zhang ,&nbsp;Jidao Xie ,&nbsp;Mingjian Gao ,&nbsp;Shuxin Huang ,&nbsp;Ruihan Xiong ,&nbsp;Hao Luo","doi":"10.1016/j.apgeochem.2025.106502","DOIUrl":"10.1016/j.apgeochem.2025.106502","url":null,"abstract":"<div><div>The phosphorite dissolution and aqueous species release play a pivotal role in the global phosphorus (P) cycle. To elucidate differences in dissolution mechanisms between phosphorite of different weathering degrees, three phosphorite samples (with high, moderate, and low weathering degrees) were collected from field environments; then, a series of mineralogical characterizations coupled with dissolution experiments were conducted. Compared to primary phosphorite, weathered phosphorite exhibited substantial depletion of carbonate minerals, while silicate minerals and phosphate minerals were relatively enriched, and secondary minerals (e.g., FePO₄ and CaF₂) were formed. Furthermore, the dissolution rates of phosphorite samples within a pH range of 3–7 were determined using a mixed-flow reactor. The results demonstrated a negative linear relationship between the logarithm of dissolution rate and pH (R² = 0.54–0.94). The P release rate constant (from 0.7 to 1.52 mol g⁻¹ s⁻¹) and kinetic reaction order (from 0.58 to 0.74) of weathered phosphorite were significantly higher than those of primary phosphorite. We modeled the co-dissolution behavior of associated minerals with fluorapatite using transition state theory. Calcite exhibited the strongest inhibitory effect on fluorapatite dissolution, whereas the effects of other minerals were relatively weak. In the column leaching experiment, compared to the primary phosphorite, the elements released from weathered phosphorite were predominantly present in ionic forms with a higher migration capability. During the leaching process, phosphate minerals in phosphorite were mainly converted to Exchangeable/loosely bound P (Ex-P), Iron-bound P (Fe–P), and Calcium-bound P (Ca–P); Ca²⁺ and CO₃²⁻ were mainly converted to dolomite, and F⁻ was mainly converted to fluorite and fluorapatite. This systematic investigation provides critical insights into weathering-driven mineralogical evolution and its mechanistic control on phosphorite dissolution.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106502"},"PeriodicalIF":3.1,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655432","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}

{"title":"Mechanisms controlling the release of inorganic contaminants, organic matter fractions, and ammonium from solid landfill waste: pH dependent leaching experiments and geochemical modelling","authors":"Frank van Raffe ,&nbsp;Joris J. Dijkstra ,&nbsp;Rob N.J. Comans","doi":"10.1016/j.apgeochem.2025.106503","DOIUrl":"10.1016/j.apgeochem.2025.106503","url":null,"abstract":"<div><div>With the intention of making landfilling more sustainable, three full-scale projects have been set up to investigate the effects of leachate recirculation and aeration on the stabilization of contaminants. Prior to this (an)aerobic stabilization, solid waste was sampled from all three landfills to identify the mechanisms behind contaminant leaching and stabilization, as a reference point for evaluation of the treatment effects at a later stage of the project. Processes underlying the leaching of a wide range of inorganic contaminants were identified using a combined approach of pH dependent leaching experiments, organic matter fractionation, and geochemical modelling. We additionally focused on organic matter, being an important surface controlling the leaching of inorganic elements, and ammonium, for which compliance with intended environmental limit values for sustainable landfill management is challenging for many landfills. Three types of pH dependent leaching behaviour could be identified for the investigated elements: non-reactive behaviour, anionic behaviour, and cationic behaviour. Reactive elements, including ammonium, showed maximum dissolved concentrations around the upper and lower ends of the pH range, while leaching of non-reactive elements was pH-independent. Organic matter became increasingly soluble with increasing pH, while its relative composition became increasingly enriched in fractions reactive for metal binding, most notably humic acid, only for the most organic landfill. The organic signature of the waste samples, together with their varying organic matter content, resulted in distinct differences in leaching behaviour between landfills. These differences result from the seemingly strong influence of organic matter on the pH at which minimum solubility of elements occurs, being lower for elements with higher organic matter binding affinity, an effect being more pronounced for more organic-rich samples. The model, based on independently determined generic sorption parameters, provided adequate descriptions of most elements, yet arsenic and ammonium were poorly described due to mechanisms not captured by the model while chromium was inadequately described due to limitations of the current binding parameters. As the three landfills have been shown to differ strongly with respect to waste properties (e.g. organic versus. inorganic) an important outcome of this study is that landfill-specific combinations of proposed treatment strategies (aeration, leachate recirculation) are necessary to reduce the leaching of specific contaminant groups to below limit values and are anticipated to be most effective for less mature landfills characterized by a lower ratio of solid to dissolved OM.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106503"},"PeriodicalIF":3.1,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144665804","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}

{"title":"Mechanisms of arsenic and iodine co-enrichment in shallow groundwater from typical fluvial plain and littoral plain of the Lubei plain in the lower Yellow River, China","authors":"Chongsheng Lu ,&nbsp;Wengeng Cao ,&nbsp;Xiangzhi Li ,&nbsp;Yu Ren ,&nbsp;Yanyan Wang","doi":"10.1016/j.apgeochem.2025.106504","DOIUrl":"10.1016/j.apgeochem.2025.106504","url":null,"abstract":"<div><div>High arsenic (As) and iodine (I) groundwater in shallow aquifers have been extensively investigated, but the co-enrichment under different environments is not well-understood. To address these issues, we explored the hydrochemistry of groundwater in typical fluvial plain (FP) and littoral plain (LP) of the Lubei Plain, and elucidated the source apportionment, further revealed its control mechanism on As and I enrichment. Results showed that the groundwaters in FP were mainly HCO₃–Mg·Ca and in LP were mainly Cl–Na. Silicate weathering (35.6 %), evaporite dissolution (26.9 %), and reductive dissolution (20.1 %) dominated hydrochemistry in FP, but in LP were evaporation-seawater intrusion (32.8 %) and silicate weathering (29.3 %), followed by reductive dissolution of Mn (22.5 %) and the Fe minerals (15.4 %). Furthermore, the reductive dissolution of Fe(III) and silicate weathering were the dominat processes for As and I co-enrichment. Specifically, groundwater As release were controlled by the reductive dissolution of Fe(III) and the competitive adsorption of HCO₃⁻ in LP, while promoted by the reductive dissolution of Fe(III) and silicate weathering in FP. Groundwater I enrichment were driven by silicate weathering and seawater intrusion in LP, but facilitated by reductive dissolution of Fe–Mn minerals and silicate weathering in FP. Risk assessment results showed a higher risk of groundwater As than I, especially for children both in LP (23.3 %) and FP (35.5 %). This work has enriched the co-enrichment mechanism of As and I, providing a basis for the safe utilization of groundwater in the Lubei Plain.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106504"},"PeriodicalIF":3.1,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655450","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}

{"title":"The gangue sponge: implications for in-situ/heap leaching of chalcopyrite","authors":"Mareike Rosemann ,&nbsp;Barbara Etschmann ,&nbsp;Luis Verdugo ,&nbsp;Kalotina Geraki ,&nbsp;Nick D. Owen ,&nbsp;John O'Callaghan ,&nbsp;Nicolas Meisser ,&nbsp;Bin Hu ,&nbsp;Luke Vollert ,&nbsp;Joël Brugger","doi":"10.1016/j.apgeochem.2025.106500","DOIUrl":"10.1016/j.apgeochem.2025.106500","url":null,"abstract":"<div><div>As the demand for copper increases, processing increasingly low-grade ore has become a critical challenge. Most of these ores are dominated by aluminosilicate gangue minerals, among which Fe-bearing phyllosilicates are the most reactive. The effect of Fe-bearing minerals on the acid leaching of chalcopyrite, the most common primary Cu ore mineral was investigated by comparing mixtures of chalcopyrite with (i) chamosite, (ii) berthierine-chamosite, and (iii) pyrite. The lixiviant consisted of solutions with 0.1 <em>m</em> Fe₂(SO₄)₃ + 0.3 <em>m</em> H₂SO₄, and the experiments were conducted in an orbital shaking water bath at 50 °C for 43 days. The solution pH increased and Eh decreased for all systems, resulting in conditions that became less optimal for Cu recovery. Scanning electron microscope imaging highlighted the porous nature and variable elemental composition of the (partially) dissolved phyllosilicate minerals/amorphous-silica-residue after leaching. Micro X-ray Absorption Near Edge Structure (μXANES) measurements revealed that sulfur exists in multiple oxidation states both <em>within</em> the silicate gangue and <em>around</em> chalcopyrite, emphasising how the formation of an amorphous-silica-residue increased the complexity of the system. This complexity is related to the fact that (partial) dissolution of phyllosilicate gangue minerals during acid leaching results in the release of ions that change the solution chemistry; and form an amorphous-silica-residue, that contains numerous pores. These pores can act as local micro-reactors with non-equilibrium conditions and promote a heterogenous chemical composition. Subsequent mineral surface-fluid interactions in (partially) dissolved phyllosilicate/amorphous-silica-residue pores can vary, depending on the local chemical composition, making the leaching behaviour of chalcopyrite highly dependent on local conditions and on the mineralogical composition of the ores.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106500"},"PeriodicalIF":3.1,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670582","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}

{"title":"Intermediate oxidation products from pyrrhotite grains in natural waste rock: A synchrotron study using Fe K-edge XANES","authors":"Lianna J.D. Smith ,&nbsp;Dogan Paktunc ,&nbsp;David W. Blowes","doi":"10.1016/j.apgeochem.2025.106501","DOIUrl":"10.1016/j.apgeochem.2025.106501","url":null,"abstract":"<div><div>Sulfide mineral oxidation releases acidity, sulfate, iron and trace element impurities to the environment. Iron K-edge X-ray absorption near edge spectra (XANES) were collected across transects of partially oxidized pyrrhotite grains in natural samples of waste rock and compared to measurements conducted on standards of ferric iron, ferrous iron, and compounds of mixed oxidation states. The XANES spectra were analyzed by pre-edge centroid deconvolution and linear combination fitting. Linear combination fitting of the pre-edge region and energy range of the XANES spectra (7070–7220 eV) produced best fits with differing species and higher ferric iron contributions (difference of typically f &lt; 0.1) than linear combination fitting of the XANES energy range. Deconvolution of the pre-edge centroids produced centroid energies that were correlated to the ferric iron contribution of the linear combination best fits of both the pre-edge and full spectrum, but a ferric iron content below a threshold value may affect the centroid energy. Ferrous iron standards that exhibited oxidation characteristics maintained a pre-edge centroid energy characteristic of ferrous iron species, and several transect spots at a calculated ferric iron contribution of f ≈ 0.2 exhibited a 0.6 eV range in pre-edge centroid energies. This study provides insight into sulfide oxidation mechanisms, including the formation and transformation of minerals, and implications for the retention and release of sulfide oxidation products and trace elements to the environment.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106501"},"PeriodicalIF":3.1,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670580","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}

{"title":"Widespread occurrence of amphibole minerals in Paris urban dust samples: a mineralogical tracer of urban wear?","authors":"Pierre Le Pape ,&nbsp;Guillaume Morin ,&nbsp;Benoît Baptiste ,&nbsp;Thierry Allard ,&nbsp;Etienne Balan ,&nbsp;Ludovic Delbes ,&nbsp;Claire Carvallo ,&nbsp;Clara Vaccaro ,&nbsp;Maëva Philippe ,&nbsp;Sophie Ayrault ,&nbsp;Cécile Quantin ,&nbsp;Gaël Monvoisin ,&nbsp;François Guyot","doi":"10.1016/j.apgeochem.2025.106497","DOIUrl":"10.1016/j.apgeochem.2025.106497","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Manufactured infrastructures of urban areas, including buildings and roads, are contributors of solid particles to the environment due to wear processes and further weathering. Mineral dusts produced by such mechanisms are transported by air or water across urban compartments until they accumulate in surrounding natural and artificial sediment reservoirs, mixing with other minerals of geogenic sedimentary origin. With the expansion of artificialized urban surfaces over time, the contribution of urban-sourced minerals is expected to increase in sediment fluxes, thus taking an increasing importance in biogeochemical cycles. In this study, we postulate that mineral particles emitted from specific man-made materials could be traced in different compartments of urban environments on the basis of their mineralogical signature. Such identified urban mineralogical components could then serve as useful markers to monitor urbanization wear processes and subsequent emprise of urbanization at the regional scale. Here, we have analyzed a collection of urban samples, which comprises urban dusts, road sediment deposits, suspended particulate matter from the Seine and Orge rivers near Paris, and sediments accumulating in stormwater basins along high traffic roads in the Paris region (N118, N104). In almost all of the solid samples studied (n = 34), whose sampling span over a ten-year period, we show by powder X-ray diffraction (XRD) the presence of minerals belonging to the amphibole group, which are necessarily derived from human activities since these minerals do not belong to the Parisian sedimentary basin. Detailed analysis of a mineral pellet embedded in bitumen of road treads sampled in a Paris street by analytical electron microscopies and Rietveld refinement analysis of powder XRD pattern show that a ferro-magnesio-actinolite is a major constituent (17 wt%) of this road material. Further analysis of an amphibole grain in a road dust sample by single crystal X-ray diffraction also points to such FeMg-actinolite of Ca&lt;sub&gt;2.15&lt;/sub&gt;Mg&lt;sub&gt;2.44&lt;/sub&gt;Fe&lt;sub&gt;2.56&lt;/sub&gt;Si&lt;sub&gt;8&lt;/sub&gt;O&lt;sub&gt;22&lt;/sub&gt;(OH)&lt;sub&gt;2&lt;/sub&gt; composition. Other samples collected in the vicinity of areas subjected to road water runoff also contain amphibole minerals of close crystal-chemical composition to this FeMg-actinolite, likely designating road aggregates as sources of amphiboles in our broad set of samples. A large distribution of sizes was observed for amphibole particles using electron microscopy, from massive (100-10 μm) to micrometric packages of elongated mineral particles, likely produced by cleavage of massive particles. The presence of micrometric minerals with elongated fiber habit raises questions about public exposure to such urban dusts. This amphibole signature is also detected in samples of river suspended particulate matter from strongly artificialized urban areas, including in a punctual sample collected in the Seine River, which emphasizes the pervasive oc","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106497"},"PeriodicalIF":3.1,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144679811","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}

{"title":"Reactive transport modeling of CO2 and CH4 plumes during a gas-rich water leakage in a shallow carbonate freshwater aquifer","authors":"David Segura ,&nbsp;Nathalie Collard ,&nbsp;Adrian Cerepi ,&nbsp;Corinne Loisy","doi":"10.1016/j.apgeochem.2025.106495","DOIUrl":"10.1016/j.apgeochem.2025.106495","url":null,"abstract":"<div><div>The recent advances in geological carbon capture and storage and the worldwide proliferation of such projects to reach net-zero emissions by 2050 highlight the importance of investigating the risks associated with CO₂ leakage from carbon storage reservoirs into shallow aquifers. A recent experiment indicates that residual CH₄ from legacy hydrocarbon fields could be a potential early indicator of CO₂ leakage. In this study, numerical reactive transport simulations are performed to examine the reasons behind the different behavior of CH₄ in regard to CO₂ as well as its potential and limitations as a monitoring parameter. The base case model was calibrated using a large data set, including a tracer test, major element concentrations, dissolved CO₂ and CH₄ concentrations, and pH monitoring.</div><div>The results show that the delay of CO₂ with respect to CH₄ is likely related to sorption, which plays a significant role in CO₂ retardation but has a minimal effect on CH₄ transport. The presence of clay minerals (montmorillonite and illite) did not significantly change the delay between the two gases. Furthermore, CO₂ retardation was found to increase in a scenario with a lower natural groundwater CO₂ concentration. The CH₄ oxidation simulation revealed that oxidation decreased the CH₄ concentration below the CH₄ concentrations from baseline water reported in the literature, suggesting that CH₄ oxidation is a critical process able to reduce the efficiency of CH₄ monitoring and should be considered if CH₄ monitoring is implemented.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106495"},"PeriodicalIF":3.1,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634192","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}

{"title":"Organic P poses high releasing risk from sediments in lake with long history of eutrophication and algal blooms","authors":"Yong Liu ,&nbsp;Yanlin Yang ,&nbsp;Dengjun Wang ,&nbsp;Xue Feng ,&nbsp;Guocheng Wang ,&nbsp;Zhihui Dai ,&nbsp;Zuxue Jin ,&nbsp;Jingfu Wang","doi":"10.1016/j.apgeochem.2025.106499","DOIUrl":"10.1016/j.apgeochem.2025.106499","url":null,"abstract":"<div><div>Organic phosphorus (P_o) is an important component of sediment P in eutrophic lakes and may play a crucial role in maintaining eutrophication, but this is often overlooked. This study analyzed the contents, various chemical forms of P_o in surface sediments collected from the Dianchi Lake in China, with long history of eutrophication and algal blooms. The simultaneous release of P_o and inorganic P (P_i) from the collected sediments under varied pH, temperatures, and oscillation simulation conditions was also investigated. The results showed that: (1) P_o accounts for 42.3 %–49.3 % of the total P (P_t), and contributs almost equally to P_i toward sediment P load. Organic residues such as endophytic algae are likely the main source of P_o in sediments; (2) P_o in sediments was primarily in the forms of NaHCO₃-P_o, HCl-P_o, and residual-P_o (Res-P_o) (over 90 % of P_o). The labile P_o (LP_o) and moderately labile P_o (MLP_o) components accounted for about 60 % of total P_o, indicating its significant potential for participation in the P biogeochemical cycles; (3) The simultaneous release of P_o and P_i from the sediments was significantly affected by pH, temperature, and oscillation simulation conditions. Especially the simultaneous release of P_o relative to P_i becomes consistently higher and shows a significant positive correlation with the release of P_t (<em>P</em> &lt; 0.01), indicating P_o poses high releasing risk from sediments in the Dianchi Lake. Our findings suggest that against the backdrop of increasing eutrophication worldwide, the control of internal P_o pollution in closed water systems (e.g., lake) is urgently needed.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106499"},"PeriodicalIF":3.1,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144611655","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}