Applied Geochemistry最新文献

{"title":"Evaluating the sources and enrichment of rare earth and trace elements in sediment of Little Zab River, Sardasht, Northwest Iran","authors":"Fatemeh Shalbaf,&nbsp;Meisam Rastegari Mehr,&nbsp;Ata Shakeri","doi":"10.1016/j.apgeochem.2025.106541","DOIUrl":"10.1016/j.apgeochem.2025.106541","url":null,"abstract":"<div><div>The geochemistry of rare earth and trace elements in sediments provides insights into their origin and the potential effects of human activity on the river ecosystem. This study examined the concentration, bioavailability, and sources of heavy metals and rare earth elements in sediments of the Little Zab River in West Azerbaijan province (Iran), using a combination of analytical techniques (total concentration and selective extractions) and data analysis (enrichment factors, rare earth anomalies, advanced statistical analysis). Average concentrations of As, Cr, Cu, Fe, Ni, Pb, and Zn were 9.11, 163.71, 37.47, 36,684.3, 99.41, 8.94, and 85.76 mg/kg, respectively, with nearly half existing in the residual phase, therefore non-bioavailable. The Positive Matrix Factorization (PMF) model identified four factors reflecting semi-natural, urban, agricultural, and industrial origins, beside a shared urban-agricultural source for heavy metals. Cr and Ni showed higher concentrations than guideline values in most sampling stations (even in the upstream sample). Total REE concentrations ranged from 88.6 to 173.5 mg/kg, averaging 127.6 mg/kg, with a positive Eu anomaly. Correlation analysis and comparisons to European shale and continental crust standards suggested a terrestrial origin for the REEs. These findings indicate that urban and agricultural activities around the Little Zab River have not significantly disrupted its natural ecosystem. However, it is shared between different countries and is prone to transboundary pollution.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"193 ","pages":"Article 106541"},"PeriodicalIF":3.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020853","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":"Mineralization processes in the Yaotoushan rare metal deposit in northern Mufushan batholith, central China: Constraints from geochronology and mineralogy","authors":"Ze Liu ,&nbsp;Zhenyu Chen ,&nbsp;Peng Li ,&nbsp;Jiankang Li ,&nbsp;Pengfei Jiang ,&nbsp;Jin Yin ,&nbsp;Zhe Xue","doi":"10.1016/j.apgeochem.2025.106539","DOIUrl":"10.1016/j.apgeochem.2025.106539","url":null,"abstract":"<div><div>The Mufushan area in central China represents a major concentration zone for rare metal ores. It has undergone a complete magmatic-hydrothermal evolutionary process, leading to the widespread distribution of pegmatite deposits. However, the genetic link between large batholith magmatism and rare metal mineralization remains unexplored, limiting the establishment of ore-forming models for such batholiths. The newly identified Yaotoushan rare metal deposit occurs at the contact between two-mica granite and the Lengjiaxi Group on the northern margin of the Mufushan batholith. The mineralized pegmatites in this deposit are classified as microcline-albite pegmatite, amazonite-albite pegmatite, and albite pegmatite. This study investigated the mineralogical features of these pegmatite types to constrain their metallogenic ages and elucidate the magmatic-hydrothermal evolution of the Yaotoushan system. Chronological and mineralogical evidence indicated two distinct metallogenic stages. The magmatic stage (127.6 ± 0.6 Ma) was characterized by Be–Nb–Ta mineralization. Fractional crystallization concentrated Be, Nb, and volatiles in the residual melt, producing Ta-poor columbite-(Mn) and beryl. This metallogenic age was defined by the U–Pb dating of columbite-(Mn). The subsequent hydrothermal stage (123.0 ± 1.1 Ma) involved Li mineralization combined with the secondary enrichment of Be, Nb, and Ta, as determined by the U–Th-Pb_total chemical age of uraninite. The interaction between hydrothermal fluids and primary minerals markedly increased Li and F in micas and Cs in beryl, resulting in the crystallization of Ta-rich columbite-(Mn), trilithionite, lepidolite, and bertrandite. Quantitative analysis demonstrated that the transformation of beryl into bertrandite-enriched BeO was nearly threefold, confirming the critical role of hydrothermal activity in secondary rare metal enrichment. The hydrothermal fluid composition (Li, F, Cs, Ta) was consistent with the evolutionary trend of pegmatite melts, indicating derivation from late-stage magmatic fluid exsolution. Metasomatic processes facilitated the Be–Nb–Ta–Li mineralization. Additionally, a comparison with global LCT-type pegmatites suggests that the Yaotoushan deposit exhibited a similar degree of evolution and therefore possessed significant metallogenic potential for rare metals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"192 ","pages":"Article 106539"},"PeriodicalIF":3.4,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932463","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":"Effect of acetate and chloride on Pb sorption onto clinoptilolite at geothermal conditions","authors":"Val Maverick Abecia ,&nbsp;Sonia Salah ,&nbsp;Mirela Vasile ,&nbsp;Ben Laenen ,&nbsp;Simona Regenspurg ,&nbsp;Valérie Cappuyns","doi":"10.1016/j.apgeochem.2025.106533","DOIUrl":"10.1016/j.apgeochem.2025.106533","url":null,"abstract":"<div><div>Naturally occurring radioactive materials generated in geothermal installations comprise minerals and amorphous precipitates (scales). Scales like galena (PbS) are often mitigated by anti-scalants, which upon degradation, potentially form organic precipitates and may be linked to elevated ²¹⁰Pb activities. An alternative to anti-scalants is Pb removal by sorption onto natural zeolite (clinoptilolite). In this paper we present the results of sorption experiments to evaluate the effect of acetate (OAc<span><math><msup><mrow></mrow><mrow><mo>−</mo></mrow></msup></math></span>, proxy for low molecular weight organics in geothermal brine) and salinity on Pb sorption. The results reveal that Pb is efficiently sorbed (47%–99%) onto clinoptilolite across all tested conditions. The presence of OAc<span><math><msup><mrow></mrow><mrow><mo>−</mo></mrow></msup></math></span> in solution resulted in a slightly decreased (<span><math><mo>≤</mo></math></span>5%) Pb sorption suggesting a minimal effect on sorption efficiency, while the presence of Cl<span><math><msup><mrow></mrow><mrow><mo>−</mo></mrow></msup></math></span> decreased sorption significantly (<span><math><mo>∼</mo></math></span>18%–20%). Empirical sorption isotherm fitting and mechanistic modeling was implemented in PHREEQC to simulate sorption mechanisms for Pb, and to further elucidate the effect of OAc<span><math><msup><mrow></mrow><mrow><mo>−</mo></mrow></msup></math></span> on the sorption processes. The outcomes of the present study suggest that natural organic matter and organic-based inhibitors in the geothermal brine do not impact Pb sorption efficiency onto clinoptilolite, but the high salinity of the brine (mainly NaCl) most likely poses an issue.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"192 ","pages":"Article 106533"},"PeriodicalIF":3.4,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989907","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":"Short-wave infrared spectroscopy for vectoring mineralization in intermediate-sulfidation epithermal deposits: A case of study on La Primavera Au–Ag vein system, Neuquén basin, Argentina","authors":"María Celeste D'Annunzio ,&nbsp;María Agustina Cócola ,&nbsp;Nora Rubinstein ,&nbsp;Leonardo Strazzere","doi":"10.1016/j.apgeochem.2025.106537","DOIUrl":"10.1016/j.apgeochem.2025.106537","url":null,"abstract":"<div><div>The La Primavera vein system is an intermediate sulfidation deposit part of the Andacollo mining district (184,600 tn @ 47,100 oz AuEq). The mineralized structures are hosted in Upper Triassic to Lower Jurassic bimodal volcanic and epiclastic rocks. These rocks underwent very low-grade metamorphism due to crustal thinning and elevated thermal gradients associated with the evolution of the rift Neuquén Basin, and are overprinted by hydrothermal alteration related to the epithermal veins. Short-wavelength infrared (SWIR) spectroscopy has been used to identify specific spectral reflectance alteration minerals features. This study integrates spectral, petrographic, and geochemical analyses of alteration minerals and whole rock, associated with La Primavera epithermal vein system, to evaluate the controls on the hydrothermal alteration and the potential of spectral techniques in mineral exploration. The results demonstrate that host rock composition plays a primary role in the development of alteration assemblages. Variations in the spectral absorption features of phyllosilicates, particularly illite and chlorite, reflect compositional differences that can be linked to relative changes in temperature and fluid acidity. The W|2200| absorption feature of illite varies systematically along sampled transects, indicating both lithological control and proximity to mineralized structures. Also, the Illite Spectral Maturity (ISM) values are higher near the veins and decrease with distance, providing a reliable vector toward mineralization. Similarly, chlorite compositional variation serves as an effective indicator of proximity to mineralized structures. Intermediate Fe–Mg chlorites occur near the veins, while Mg-rich varieties dominate distal zones. In addition, this combination of techniques has been a useful tool for distinguishing mineral phases specific to regional metamorphism from those related to hydrothermalism. In this way, spectral analysis has been proven to be a powerful tool in the initial steps of low to intermediate epithermal deposits exploration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"192 ","pages":"Article 106537"},"PeriodicalIF":3.4,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144934149","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":"A study on the morphological characteristics of geo-electrochemical halo-forming materials in the Luoboling copper–molybdenum polymetallic deposits of Zijin Mountain, Fujian Province","authors":"Caiyun Zhang ,&nbsp;Meilan Wen ,&nbsp;Jiali Zhang ,&nbsp;Yuxiong Jiang ,&nbsp;Jianting Li ,&nbsp;Yunxue Ma ,&nbsp;Panfeng Liu","doi":"10.1016/j.apgeochem.2025.106536","DOIUrl":"10.1016/j.apgeochem.2025.106536","url":null,"abstract":"<div><div>This study investigates the sources and migration mechanisms of geo-electrochemical halo-forming materials in polymetallic sulfide deposits through elemental chemical speciation analysis in various media. The research utilizes the modified BCR method and ultrasonic extraction to analyze the chemical speciation of Cu and Mo in ore samples, soils above ore bodies and non-ore bodies, and geo-electrochemical extraction samples from the Luobuling Cu–Mo polymetallic deposit along profile 264 in the Zijinshan area, Fujian Province. The findings indicate that: (1) Bornite exhibits spontaneous electrochemical dissolution in aqueous solutions, with Cu and Mo primarily present in the water-soluble fraction (WS–F). (2) In soils above ore and non-ore bodies, Cu predominantly exists in the reducible fraction (RED-F), while Mo is mainly found in the oxidizable fraction (OX-F) and residual fraction (RES-F). (3) Scanning electron microscope (SEM) and Energy dispersive spectroscopy (EDS) analyses reveal that geo-electrochemical extraction primarily targets ionic halo-forming materials, which predominantly form stable complexes and ion associates through chelation with organic material in the geo-electrochemical extraction device. Based on Spearman correlation analysis and these findings, the study suggests that the various forms of halo-forming materials extracted through geo-electrochemistry do not directly correspond to their soil forms but undergo transformation through complex processes including electrochemical dissolution, activation, and secondary enrichment. The halo-forming materials in the soil surrounding the electrodes originate from deep-seated ore bodies and migrate continuously to the surface under various geological forces. These materials are subsequently adsorbed by organic matter and iron-manganese oxides in the soil, ultimately achieving stable existence. The geo-electrochemical extraction process specifically targets these deep-originated halo-forming materials.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"192 ","pages":"Article 106536"},"PeriodicalIF":3.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989908","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":"Tectonic settings and geochronological evolution of the Xianglushan skarn tungsten deposit, Jiangnan orogenic belt: A multi-mineral age dating approach","authors":"Hu Ziqi ,&nbsp;Zhang Dexian ,&nbsp;Richard C. Bayless ,&nbsp;Xie Xiaoyu ,&nbsp;Chen Shaowei ,&nbsp;Xu Hao ,&nbsp;Zeng Shuishi","doi":"10.1016/j.apgeochem.2025.106535","DOIUrl":"10.1016/j.apgeochem.2025.106535","url":null,"abstract":"<div><div>The Jiangnan tungsten ore belt (JOB) in South China, recognized as a global significant tungsten metallogenic belt, hosts numerous economically significant skarn-type and quartz vein-type tungsten deposits. The Xianglushan tungsten deposit, a reduced skarn system dominated by scheelite mineralization, provides critical insights into regional ore-forming processes. Precise geochronological constraints are pivotal for deciphering the metallogenic evolution. In this study, we employ high-resolution laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb geochronology to analyze zircon, apatite, garnet, vesuvianite, wolframite, and scheelite from this deposit. Zircon yields Late Yanshanian U–Pb ages of 124.7 ± 1.6 Ma and 126.5 ± 0.5 Ma, while apatite records 126.4 ± 5.2 Ma. Metasomatic phases, including vesuvianite (124.2 ± 1.7 Ma) and garnet (119.3 ± 2.1 Ma), exhibit distinct age populations. Hydrothermal ore minerals demonstrate younger crystallization ages, with wolframite at 120.7 ± 4.1 Ma and scheelite at 121.6 ± 4.1 Ma. The progressive age distribution, from granite to prograde skarn silicates and retrograde ore minerals, reveals a prolonged, multistage mineralization history spanning ca. 7 Myr. Integrating geochronological data with regional tectonic evolution, we propose that the Xianglushan tungsten system formed during Late Mesozoic lithospheric extension, triggered by the rollback of the subducting Paleo-Pacific Plate beneath the South China Block.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106535"},"PeriodicalIF":3.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895805","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":"LIBS as a tool for Li-pegmatite exploration and prospect evaluation: Soil mica and soil analysis from the Carolina Tin-Spodumene Belt","authors":"Russell S. Harmon ,&nbsp;P. Louis Lu ,&nbsp;Adam C. Curry ,&nbsp;Russell M. Murray ,&nbsp;Daniel D. Richter","doi":"10.1016/j.apgeochem.2025.106534","DOIUrl":"10.1016/j.apgeochem.2025.106534","url":null,"abstract":"<div><div>Lithium is an essential element along the pathway to a high-technology future. Being able to efficiently explore for Li deposits and fully assess prospects is necessary to reduce exploration costs, shorten time between discovery and production, and minimize environmental impacts of exploration and production. Laser-induced breakdown spectroscopy (LIBS) is an analytical technology for real-time geochemical analysis in both the laboratory and the field that has potential to enhance current capabilities for Li pegmatite exploration and prospect evaluation. This study was conducted in a portion of the Carolina Tin-Spodumene Belt in Gaston County, NC at one of the largest Li-pegmatite prospects in the USA. Analysis by handheld LIBS first observed the same Li–K/Rb systematics for individual mica grains in soil as for mica in both barren quartz-feldspar and spodumene-bearing pegmatites, suggesting that soil mica analysis might be used for geochemical vectoring towards mineralized pegmatite. The contents of Li, K, and Rb in Bt horizons of residual Kanhapludult soil were determined in the field from matrix-matched LIBS calibrations along five transects across an area where a subsurface spodumene pegmatite dike was known from drilling to be present at ∼15-m depth. Unlike the situation for mica, no systematic variation was observed for soil K and Rb abundances, with K/Rb ratios not reflective of the presence of subsurface mineralization. By contrast, soil Li content spiked sharply where a sampling transect passed directly over the spodumene mineralized dike. It was also noted that soil Li abundances are significantly elevated across the domain of the Carolina Tin-Spodumene Belt of pegmatite mineralization on a regional scale compared to other Piedmont and Coastal Plain soils. Thus, there is potential for rapid soil geochemical analysis by LIBS in Li-pegmatite exploration at both local and regional spatial scales.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106534"},"PeriodicalIF":3.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144913114","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":"Historical reconstruction and impact of the 2014 mining spill on El Molinito Dam sediments (Sonora River, northwestern Mexico)","authors":"Krishia Georgina Acosta-Fimbres ,&nbsp;Martín Enrique Jara-Marini ,&nbsp;Ana Carolina Ruiz-Fernández ,&nbsp;Libia Hascibe Pérez-Bernal ,&nbsp;Joan-Albert Sanchez-Cabeza","doi":"10.1016/j.apgeochem.2025.106531","DOIUrl":"10.1016/j.apgeochem.2025.106531","url":null,"abstract":"<div><div>This study aimed to reconstruct the temporal variations of potentially toxic element (PTE) concentrations and enrichment levels in four ²¹⁰Pb-dated sediment cores, collected in Molinito Dam, NW Mexico, to assess the impacts of the 2014 mining spill on the Sonora River Basin. Sediment cores were collected with a gravity corer in February 2023; major and trace elements were analyzed through X-ray fluorescence spectrometry, except Hg and Cd, measured by atomic absorption spectrometry. Contamination degree was assessed via enrichment factor, and PTE sources were identified through factor analysis. The sediment cores spanned between 10 and 30 years; sediments were mostly composed of clayey silts, with organic matter and carbonate contents below 4 %. Element concentrations were similar in magnitude among cores, exhibiting minimal variations throughout their temporal profiles, except for distinct maxima of Mn, Fe, As, Cu, Pb, Ni, Cr, and Zn that reached different depths within each core. Most elements showed null to minor enrichment, except As, Cd, and Hg, which exhibited moderate to severe enrichment in some cores. PTE maxima were observed in sediment sections dated near 2014, which, considering the age model uncertainties, aligned with the timing of the 2014 mining spill. Additional maxima in older or younger sections were likely associated with hydrometeorological events or unreported spills. Although the enrichment factor for most PTEs was null or minor, the spill left a clear mark in the sediment record, which also showed that PTE concentrations returned to pre-event levels. These findings underscore the importance of reconstructing historical environmental conditions through sediment analysis to understand changes and evolution of aquatic ecosystems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"193 ","pages":"Article 106531"},"PeriodicalIF":3.4,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004393","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":"Chemical weathering and land use control river alkalinization and dissolved inorganic carbon in the Potomac River, USA","authors":"Shuiwang Duan ,&nbsp;Sujay S. Kaushal ,&nbsp;Erik J. Rosenfeldt ,&nbsp;Sudhir Murthy ,&nbsp;Matthew H.H. Fischel","doi":"10.1016/j.apgeochem.2025.106530","DOIUrl":"10.1016/j.apgeochem.2025.106530","url":null,"abstract":"<div><div>Many rivers in the United States have experienced noticeable increases in dissolved inorganic carbon (DIC) and alkalinity over the last few decades. This study examines possible controlling factors on DIC in the Potomac River watershed using combined spatial “hot spot” analyses and correlation analyses with data from DIC, geochemical tracers, land use, and lithology. Results showed that the DIC hotpots matched best with those of carbonate rocks, better than any land use type. Mean daily DIC flux ranged from 21.6 kg day⁻¹ km⁻¹ in carbonate sub-watersheds, higher than those from forest sub-watersheds with siliciclastic lithology (9.7 kg day⁻¹ km⁻¹), crystalline lithology in agricultural and urban watersheds (8.2 and 7.2 kg day⁻¹ km⁻¹). Although DIC concentrations in tributaries were positively correlated with calcium (Ca²⁺) plus magnesium (Mg²⁺), the slopes of the regressions showed high depletion of DIC relative to Ca²⁺+Mg²⁺ in two upper sub-watersheds affected by acid mine drainage (DIC/Ca²⁺+Mg²⁺ = 0.17) and moderate depletion in the lower urban sub-watersheds (DIC/Ca²⁺+Mg²⁺ = 0.52). A positive correlation between DIC and nitrate in agricultural sub-watersheds indicates additional DIC inputs from agricultural liming or weathering of native carbonate minerals in response to acidification from the nitrification of ammonium fertilizer. This study suggests that carbonate lithology is still the primary control on DIC concentrations and fluxes in the Potomac River watershed, but more research is needed on the effects of lime dosers, urbanization, agricultural liming, and ammonium fertilizer application on human-accelerated weathering of carbonate lithology to understand long-term trends in river alkalinization and shifting alkalinity transport to the estuary.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106530"},"PeriodicalIF":3.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886671","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":"Mineralogical and geochemical proxies from sediment cores to understand paleoclimate and sea level changes along the southwest coast of India","authors":"S. Sreekesh ,&nbsp;Meenakshi ,&nbsp;Sreerama Naik S R ,&nbsp;Pankaj Kumar ,&nbsp;Sandeep Sarpal","doi":"10.1016/j.apgeochem.2025.106532","DOIUrl":"10.1016/j.apgeochem.2025.106532","url":null,"abstract":"<div><div>Geochemical variations, among other factors, are attributable to air, water, and land interactions, which are plentiful in the coastal setting. To explore the extent of these interactions in the Vypin Island, southwest of India, three sediment cores were investigated for the mineralogical and geochemical variations. A ∼10 m long core from Kuzhuppilly with a 9 m thick sand deposit suggested a back-barrier ridge condition, largely influenced by fluvial processes. Mineralogy indicated a weakly weathered character, while geochemistry suggested arid conditions, causative of a break in sedimentation at 25–145 cm, 350–365 cm, and 940–955 cm depths with enrichment of Fe, Ti, Zr, and Mn by removal of light-weight Si and Al-rich material. In Chellanam and Munambam cores, characteristic clay and sand layers suggest two varied depositions at the bottom and top, respectively. Saline and oxic depositional conditions under higher sea levels are further complemented by presence of glauconite and kaolinite in bottom clayey sediments, found in the inner shelf depositional setting. The sandy sediments on top are deposited under freshwater conditions (Sr/Ba) but intruded by anoxic conditions indicated by Fe/Al values suggesting a fluvial reworking or deposition. Chemical index of alteration delineate increasing sediment maturity trend from Kuzhuppilly to Chellanam, and Munambam with a depositional hiatus at ∼5.5 m depth in Munambam. Further, glauconite and kaolinite suggest progressive weathering of deeper sediments. This study suggests that clayey sediments were deposited under inner-shelf conditions during higher sea levels, and a trace elemental rich layer between sand and clay proposes further sandy sediment deposition and reworking by dominant fluvial processes during lower Sea levels under semi-arid climate. The work recognizes signatures of three arid phases, regression episodes each and paleo-flood events supported by clay-sand mixed sediment layers.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"191 ","pages":"Article 106532"},"PeriodicalIF":3.4,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866242","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}