Applied Geochemistry最新文献

{"title":"The geochemical composition of Wellington soils and other New Zealand urban soils under different land-use","authors":"K.M. Rogers ,&nbsp;R. Morgenstern ,&nbsp;M.S. Rattenbury ,&nbsp;K.P. Norton ,&nbsp;C. Doogue ,&nbsp;M. Kah ,&nbsp;S.A. Sari ,&nbsp;R.E. Turnbull ,&nbsp;A.P. Martin","doi":"10.1016/j.apgeochem.2025.106485","DOIUrl":"10.1016/j.apgeochem.2025.106485","url":null,"abstract":"<div><div>A recent soil geochemical baseline survey of the Wellington urban area analysed samples collected at multiple depths across 151 sites from a mixture of residential, commercial, industrial, pasture, native forest and exotic forest land. The parent material of Wellington soils is mostly chemically invariant, requiring data outliers to be explained by environmental or anthropogenic factors. Notable concentrations above guidance level environmental standards were found in surface (0–2 cm) and shallow (2–20 cm) soils for As, Cd and Pb. The concentration of these heavy metal contaminants in Wellington soils are likely associated with human activities, as the highest concentrations correlate to more densely populated urban areas, particularly where older pre-1960s housing stock exists. This pattern of heavy metal enrichment in New Zealand urban soils relative to regional soils is also observed in comparative urban studies in Auckland and Dunedin cities. Wellington urban soils overall have lower concentrations of Cd and higher concentrations of As, Pb, and Zn compared to Auckland and/or Dunedin. In contrast, Auckland and Dunedin urban soils have a broader enrichment in some heavy metals (including Cr, Cu, and Ni) directly associated with a strong geogenic influence from underlying volcanic geological sources, while Wellington urban soils are influenced by monolithic greywacke. This study also showed that the carbon content of soils in these three centres increases by up to 66 % with increasing latitude due to better C preservation in cooler southern climates. Moreover, urban soils are found to have lower C contents than native, pasture and exotic soils due to more rapid soil turnover rates which leads to increased microbial activity, although this is also dependant on plant type, with C4 grasses commonly found in the warmer and drier climates of Auckland being more recalcitrant in soil than C3 plants. Geochemical studies from across New Zealand show that both urbanisation and underlying geology exert a strong influence on elemental soil concentrations, with the highest heavy metal values commonly associated with cities with the longest history of European settlement. Climate and land use type are also key drivers for elemental retention in shallow soils.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106485"},"PeriodicalIF":3.1,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144470563","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":"Characterization of fractured serpentinite at Shulaps, Coquihalla, and Tulameen sites in British Columbia: Implications for carbon storage","authors":"Katrin Steinthorsdottir ,&nbsp;Gregory M. Dipple ,&nbsp;Xueya Lu ,&nbsp;Sandra Ósk Snæbjörnsdóttir ,&nbsp;Randolph J. Enkin","doi":"10.1016/j.apgeochem.2025.106481","DOIUrl":"10.1016/j.apgeochem.2025.106481","url":null,"abstract":"<div><div>This study presents a geological characterization of variably serpentinized harzburgite and dunite of the Shulaps, Coquihalla, and Tulameen sites in southwestern British Columbia. Surface geological data are used to determine the injectivity and reactivity for carbon storage via shallow CO₂ injection and mineralization. Injectivity into a fracture-hosted reservoir was assessed by measuring fracture intensity and connectivity, which were quantified on an outcrop scale and considered together with the physical properties of rock samples collected from the field sites. Pervasively serpentinized harzburgite from Shulaps and Coquihalla are more fractured than partially serpentinized harzburgite and dunite. Additionally, rock mineral content, bulk rock chemical composition and dissolution rates of selected samples were used to assess reactivity. Serpentinized dunite from Tulameen is more reactive than serpentinized harzburgite. The data collected can help assess baseline data, modeling inputs, and well-targeting.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106481"},"PeriodicalIF":3.1,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144480103","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 mobility of U(VI) associated with Fe(II)-induced transformation of schwertmannite and its reductive dissolution and re-precipitation in AMD environment","authors":"Chang He ,&nbsp;Yu Ning ,&nbsp;Yilian Li ,&nbsp;Hongyan Guo ,&nbsp;Zhe Yang ,&nbsp;Sen Yang ,&nbsp;Fengcheng Jiang","doi":"10.1016/j.apgeochem.2025.106467","DOIUrl":"10.1016/j.apgeochem.2025.106467","url":null,"abstract":"<div><div>The formation and phase transformation of schwertmannite (Sch) in sulfate-rich AMD systems could significantly affect the migration and transformation of U(VI) via adsorption or co-precipitation. To explore this geochemical process, this study investigated the phase transformation of Sch and re-distribution behavior of U(VI) in simulated anaerobic AMD systems. The results demonstrated that Fe²⁺ had activated the adsorbed U(VI) through facilitating phase transformation. However, following activation by Fe²⁺, the residual U(VI) became more firmly bound to Sch than when extracted by hydrochloric acid, which could be attributed to a variety of mechanisms induced by Fe²⁺, including competitive adsorption on Sch and its reduction, dissolution and re-precipitation. Compared with Fe²⁺, pH plays a more auxiliary and enhanced role in the reduction and phase transformation of Sch. The X-ray photoelectron spectroscopy and XRD results revealed an increase in the pH-enhanced reduction of adsorbed U(VI) and structural Fe(III) by enhancing the adsorption capacity of Fe²⁺, bolstering solid–liquid electron transfer and promoting the reductive activity of the Fe²⁺ complexes formed on the Sch surface, thereby enhancing the reductive dissolution and re-precipitation of Sch coupled with competitive substitution of surface SO₄²⁻ by enriched OH⁻.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106467"},"PeriodicalIF":3.1,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298022","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 SIT model parameters for interactions of phosphate ions with Na+ and K+ ions accounting for dimerization of the H2PO4‐ anion","authors":"Andrey V. Plyasunov,&nbsp;Elena V. Cherkasova","doi":"10.1016/j.apgeochem.2025.106477","DOIUrl":"10.1016/j.apgeochem.2025.106477","url":null,"abstract":"<div><div>The SIT model is a simple yet physically sound model for activity coefficients in aqueous solutions, which has only one binary interaction parameter for each pair of cations and anions. It has long been known that the SIT model performs poorly for the thermodynamic activity data for aqueous solutions of <span><math><mrow><mi>N</mi><msub><mtext>aH</mtext><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span> and <span><math><mrow><mi>K</mi><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>. However, the previous treatment ignored the dimerization of the <span><math><mrow><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msubsup><mi>O</mi><mn>4</mn><mo>‐</mo></msubsup></mrow></math></span> anion with the formation of <span><math><mrow><msub><mi>H</mi><mn>4</mn></msub><msub><mi>P</mi><mn>2</mn></msub><msubsup><mi>O</mi><mn>8</mn><mrow><mn>2</mn><mo>‐</mo></mrow></msubsup></mrow></math></span>, which has been convincingly demonstrated, mainly in Raman experiments. Here we show that explicitly taking into account the dimerization of the <span><math><mrow><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msubsup><mi>O</mi><mn>4</mn><mo>‐</mo></msubsup></mrow></math></span> anion allows to reproduce accurately the experimental data on the stoichiometric mean ionic activity coefficients for aqueous <span><math><mrow><mi>N</mi><msub><mtext>aH</mtext><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span> and <span><math><mrow><mi>K</mi><msub><mi>H</mi><mn>2</mn></msub><mi>P</mi><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>. The data were processed using relations from the thermodynamics of partially associated electrolytes. An additional source of information were the values of the dissociation constants of phosphoric acid in <span><math><mrow><mtext>NaCl</mtext></mrow></math></span> and <span><math><mrow><mtext>KCl</mtext></mrow></math></span> solutions. In total, we determined 8 SIT parameters for the interactions of <span><math><mrow><msup><mtext>Na</mtext><mo>+</mo></msup></mrow></math></span> and <span><math><mrow><msup><mi>K</mi><mo>+</mo></msup></mrow></math></span> with different phosphate ions at 298.15 K and 0.1 MPa.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106477"},"PeriodicalIF":3.1,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322515","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":"Examination of Np(V) sorption to montmorillonite as a function of temperature (25–55 °C) and ionic strength","authors":"Fanny Coutelot ,&nbsp;Matthew Riss ,&nbsp;Deborah L. Wang ,&nbsp;Daniel T. Olive ,&nbsp;Andreas Schnurr ,&nbsp;Brian A. Powell","doi":"10.1016/j.apgeochem.2025.106466","DOIUrl":"10.1016/j.apgeochem.2025.106466","url":null,"abstract":"<div><div>Because of the prevalence of clays in rocks, soils, and sediments, and their proposed use in nuclear waste storage sites, clay materials are an important consideration in radionuclide interactions in the environment. This study examined Np(V) sorption to Na-montmorillonite as a function of temperature and ionic strength. Batch sorption experiments were conducted at 25 °C, 35 °C, 45 °C, 55 °C for 0.01, 0.1, and 1.0 M NaCl ionic strengths. The data indicate that Np(V) sorption to montmorillonite at pH values above 6 increases slightly with increasing temperature. The displacement of hydrating waters from the neptunium cation and clay surface may be the driving force behind the increased sorption, which is postulated based on the entropically driven removal of water molecules from the primary hydration sphere to bulk water. A double-layer (DLM) surface complexation model was applied to describe the Np(V) sorption data with activities of the dissolved aqueous species and estimate their associated log K values, allowing for an estimation of the adsorption enthalpy. X-ray absorption spectroscopy (XAS) measurements confirmed one of the essential assumptions for modeling at high ionic strengths: no variation in surface speciation appears between low and high ionic strength samples. XAS analysis confirmed Np(V) remained in the pentavalent oxidation state and indicated similar surface speciation for both low and high ionic strength conditions, with no evidence of Np precipitation. These results provide insights into Np(V) sorption behavior under conditions relevant to nuclear waste repositories, including elevated temperatures and high ionic strengths. The slight increase in sorption with temperature suggests Np(V) mobility may be somewhat reduced in heated repository environments. However, the overall weak sorption indicates Np(V) remains relatively mobile under most conditions studied.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106466"},"PeriodicalIF":3.1,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696609","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":"Lithium resource mapping in Afghanistan's Helmand Basin: A multi-criteria approach of zonation using the Analytic Hierarchy Process","authors":"Antarip Hazarika,&nbsp;Biswajit Thander,&nbsp;Siddhartha Kumar Lahiri","doi":"10.1016/j.apgeochem.2025.106460","DOIUrl":"10.1016/j.apgeochem.2025.106460","url":null,"abstract":"<div><div>The Helmand Basin, which spans southern Afghanistan and parts of Iran and Pakistan, is a hyperarid, endorheic region with a high potential for lithium-brine (Li-brine) deposits. Although lithium is available in nature as a primary source (for instance, granite pegmatite type) and as a secondary source of deposition in salt lakes or palaeo-salars in the subsurface, a generalised methodology for adopting a priority-based lithium exploration policy is still absent. This study, driven by a heuristic approach, specifically explores the Helmand basin's tectonic complexity, as well as its climatic and geological conditions, which make it a promising target for Li-brine exploration. By utilising the Analytic Hierarchy Process (AHP), we systematically identified potential Li-source and accumulation zones by parameterising key factors such as hydrothermal activity, Li-rich lithology, crustal thickness, arid climate, and tectonic subsidence. The spatial zonation model developed in this study predicts areas with varying probabilities for Li-brine systems, highlighting the northeastern basin as the most promising for Li sources. Specific recharge and transport pathways were identified, mapping Li migration from source zones to high-elevation lakes, including Ab-e Istada and Dasht-e Nawar. Additionally, the Godzareh Depression emerged as a significant Li-brine accumulation site, benefiting from regional recharge throughout the entire basin. This study demonstrates the utility of AHP in integrating complex geospatial data for precise Li-brine exploration. The results provide a strategic framework for guiding economically viable lithium resource development, positioning the Helmand Basin as a key contributor to the global Li-brine supply.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106460"},"PeriodicalIF":3.1,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298020","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":"Uranium enrichment in altered metasedimentary rocks of Jahaz uranium deposit, North Delhi fold belt, Rajasthan, India: Inferences from whole-rock geochemical studies","authors":"Priyanka Mishra ,&nbsp;Rajagopal Krishnamurthi ,&nbsp;Ajit Kumar Sahoo ,&nbsp;Shailendra Kumar Sharma","doi":"10.1016/j.apgeochem.2025.106476","DOIUrl":"10.1016/j.apgeochem.2025.106476","url":null,"abstract":"<div><div>Jahaz deposit is one of the promising Na-metasomatic uranium deposits along the “<em>albitite line</em>” and is hosted in the Meso-Proterozoic metamorphic rocks of the North Delhi Fold Belt, Rajasthan, India. This article presents whole-rock geochemical analyses of major, trace, and rare-earth elements of less to moderately altered and albitized rocks, which are used to quantify the exchange of chemical components during fluid-rock interaction. The alteration box plot indicates the intensity of alterations (albitization, chloritization, calcitization, sericitization, pyritization), and it is inferred that Na-Ca-Mg-K metasomatism was responsible for the formation of albite, chlorite, calcite, and sericite in the altered rocks. Isocon diagrams have been constructed using major and selected trace element concentrations of less to moderately altered and albitized garnetiferous quartz biotite schist/amphibolite to determine the net loss and gain of elements during rock-fluid interaction. The correlation coefficients indicated that elements such as Zr, Nb, Hf, and Ti were less mobile during fluid-rock interaction. Isocon analyses show that the albitized garnetiferous quartz biotite schist is significantly enriched in U, Na, Mg, Fe, Ca, Mo, Cu, Rb, and depleted in K, Pb, Ba, Ni, Zn. Albitized amphibolites are enriched in Na, Cu, Mg, Cu, Y, Cr, Se, Ni, K, LOI and depleted in Ba, Co, Pb, Zn, Ca, P, Mn, Fe. The low Th/U ratio of albitized garnetiferous quartz biotite schist indicates that the albitized rocks are significantly enriched in uranium. Hence, uranium enrichment is positively correlated with Na, Mo, Cu, Th, Zr, LOI, and light rare-earth elements of albitized garnetiferous quartz biotite schist/amphibolite in the Jahaz uranium deposit. These results are similar to Kirovograd and Novoukrainka (Ukraine), Lagoa Real (Brazil), Valhalla (Australia), Longshoushan (China), Aricheng (Guyana) and Coles Hill (USA) Na-metasomatic uranium-deposits.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106476"},"PeriodicalIF":3.1,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535968","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":"Geochemistry of geothermal well gases from superhot zones of Larderello, Italy","authors":"Fabrizio Gherardi,&nbsp;Gabriella Magro","doi":"10.1016/j.apgeochem.2025.106480","DOIUrl":"10.1016/j.apgeochem.2025.106480","url":null,"abstract":"<div><div>At Larderello, granitic intrusions into a thinned continental crust act as the heat source for the regional thermal anomaly, and a major seismic reflector (K-horizon) extends all over the field at 3–6 km depth. The geological meaning of the K-horizon is still under debate, and some authors believe that the presence of high-P, supercritical fluids may explain this feature. In late 2017, a deep well was deepened at Larderello to search for supercritical fluids. Temperatures more than 500 °C were estimated at the bottom hole, associated with a leak-off pressure of about 30 MPa, though an exploitable reservoir was not proven. The lack of relevant fluid entries in concomitance with the crossing of the local major seismic reflectors, during the deepening of the well, raised fundamental questions about the geothermal significance of these seismic reflectors, as well as their relevance as possible targets for drilling and industrial exploitation of supercritical fluids.</div><div>To gain some insight into the super-hot horizons of the Larderello geothermal field, we present new geochemical data on gases from productive wells approaching the K-horizon, and/or closely related to granitic bodies in the southern and eastern sectors of the geothermal field. The wells considered here discharge a single gaseous phase, draining a vapor-dominated reservoir at temperatures up to 375 °C. The stable isotope signature of steam is indicative of enhanced water-rock interactions at depth (oxygen-shift), and the C–He isotope systematics allowed the identification of a predominant crustal source for CO₂. The He isotope distribution at the surface mirrored a dynamic balance between crustal- and mantle-derived fluids, as also indicated by the relative abundances of N₂, Ar, He, and Ne.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106480"},"PeriodicalIF":3.1,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144298021","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":"Deciphering the magmatic evolution of the northern lesser antilles Arc: Insights from major-trace element and Pb isotopic analyses of submarine tephra","authors":"Zhiyu Han ,&nbsp;Fei Wang ,&nbsp;Liekun Yang ,&nbsp;Wenbei Shi ,&nbsp;Yinzhi Wang","doi":"10.1016/j.apgeochem.2025.106463","DOIUrl":"10.1016/j.apgeochem.2025.106463","url":null,"abstract":"<div><div>The Lesser Antilles Arc (LAA), a subduction-driven volcanic system, exhibits pronounced geochemical and isotopic variations. Montserrat and Guadeloupe serve as key locations for elucidating magmatic processes in the northern LAA region. This study integrates marine tephra records from IODP Expedition 340 borehole U1396A with terrestrial volcanic data to reconstruct the magmatic evolution of the northern LAA over an extended timescale (∼4.5 Ma to present). Through grain morphology analysis, Pb isotopes, and major/trace element compositions of whole rocks and melt inclusions, we demonstrate that the Pb isotopic compositions of samples from Montserrat and Guadeloupe are primarily controlled by magmatic source regions rather than crustal contamination. Based on mixing models involving depleted mantle and subducted slab components, Guadeloupe exhibits greater sediment input compared to Montserrat, and such sediment contributions must be added as melt additions to the Guadeloupe magmatic system to account for its elevated Th/Nd ratios (0.36). Although significant differences in sediment contributions exist between Guadeloupe and Montserrat, fluid inputs show no discernible distinction. Furthermore, the contrasting Eu and Sr signatures between Guadeloupe and Montserrat are likely attributable to plagioclase accumulation rather than fundamental differences in magmatic differentiation processes. This study extends the volcanic activity history of the northern Lesser Antilles Arc back to 4.5 million years ago, filling a critical gap in previous studies that were limited to terrestrial volcanic rocks.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106463"},"PeriodicalIF":3.1,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144270224","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":"Millimeter-scale leaf litter placement modulates carbon dioxide and methane emissions in wetlands","authors":"Hao Liu ,&nbsp;Yining Zhang ,&nbsp;Yu-Jia Cai ,&nbsp;Zi-Yan Liu ,&nbsp;Liang Li ,&nbsp;Ya-Qin Wang ,&nbsp;Xiao Shu ,&nbsp;Royston Goodacre ,&nbsp;Zheng Chen","doi":"10.1016/j.apgeochem.2025.106475","DOIUrl":"10.1016/j.apgeochem.2025.106475","url":null,"abstract":"<div><div>Flooded soils play a crucial role in global carbon cycling, acting as significant reservoirs of soil organic carbon and sources of carbon emissions. Leaf litter, especially from local vegetation, is a key contributor to soil organic carbon formation in these ecosystems, with its decomposition driving the production of carbon dioxide (CO₂) and methane (CH₄). Although numerous studies have examined the factors influencing leaf litter decomposition and associated greenhouse gas emissions, the impact of millimeter-scale variations in leaf litter placement within the soil-water interfaces (SWI) has received little attention. This study hypothesizes that even small changes in burial depth could significantly affect the emission patterns of CO₂ and CH₄. To test this hypothesis, a microcosm experiment was conducted to monitor gas fluxes and physicochemical profiles in treatments with leaf litter placed uncovered at the SWI (LU) or covered by a thin (10 mm) soil layer (LC). The results demonstrated substantial shifts in emissions: cumulative CH₄ emissions were more than doubled in the LC group (115.3 μgC) compared to the LU group (42.5 μgC), while cumulative CO₂ emissions were reduced by 25 % in the LC group (77 mgC) versus the LU group (103 mgC). Consequently, the overall global warming potential over a 20-year horizon (GWP20) was 13.2 % lower for the LC treatment (280.7 mgCO₂e) compared to the LU treatment (323.3 mgCO₂e). These findings advance our understanding of wetland carbon dynamics by revealing that a millimeter-scale change in leaf litter placement significantly alters the spatiotemporal patterns and partitioning of CO₂ and CH₄ emissions, highlighting the critical role of micro-scale heterogeneity in regulating greenhouse gas fluxes. Moreover, our results demonstrate a decoupling of CO₂ and CH₄ responses to this small-scale environmental variation, ultimately leading to a reduction in overall global warming potential despite increased methane release.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"190 ","pages":"Article 106475"},"PeriodicalIF":3.1,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144322514","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}