Hydrogeochemical processes driving elevated Arsenic and Fluoride in the Texas Gulf Coast Aquifer

IF 3.5 3区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Applied Geochemistry Pub Date : 2026-03-01 Epub Date: 2026-01-29 DOI:10.1016/j.apgeochem.2026.106713

Hailey N. Goodwin , Taehyun Roh , Reid Buskirk , D. Kirk Nordstrom , Franco Marcantonio , Peter S.K. Knappett

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引用次数: 0

Abstract

Dissolved arsenic (As) and fluoride (F) concentrations frequently exceed the United States Environmental Protection Agency (US EPA) drinking water standards in groundwater wells screened within the three aquifers (Chicot, Evangeline, Jasper) that comprise the Gulf Coast Aquifer (GCA) in Texas. The primary objective of this study is to identify the hydrological and geochemical processes that mobilize dissolved groundwater As and F in each aquifer across a north-south climate gradient from humid to semi-arid. Comprehensive chemistry was analyzed from 1164 water samples taken from 534 wells between 2002 and 2022 and reported in a public database of the Texas Water Development Board (TWDB). Surface and geologic sources of As and F were tested by observing their spatial correlation to land use and geologic layers. Multivariate analysis revealed that in the Northern and Central climate zones As covaries with dissolved iron (Fe) and/or manganese (Mn), whereas F varies with bicarbonate (HCO₃), sodium (Na), and pH. In the Southern climate zone As and F covary with vanadium (V). Plausible chemical reactions that generated As and F were analyzed with geochemical plots and stoichiometric inverse modeling. The dissolved products of silicate hydrolysis and cation exchange were evident along all flowpaths. The removal of Ca from solution through cation exchange drives calcite and fluorite dissolution, which is inferred to be the primary source of F to groundwater in the Northern and Central climate regions, whereas the reductive dissolution Fe- and Mn-oxides releases dissolved As. Arsenic and F are released to Southern aquifers primarily by silicate weathering of the Catahoula Formation volcanic ash layers. This study reveals the changing drivers of As and F release across a 650 km wide region with varying geology and climate. Understanding these drivers is important for deciding the best strategy for avoiding consumption of the polluted groundwater or making the contamination worse through land use or groundwater pumping.

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水文地球化学过程导致德克萨斯州墨西哥湾沿岸含水层中砷和氟化物升高

在构成德克萨斯州墨西哥湾沿岸含水层（GCA）的三个含水层（Chicot、Evangeline、Jasper）内筛选的地下水水井中，溶解的砷（As）和氟(F)浓度经常超过美国环境保护局（US EPA）的饮用水标准。本研究的主要目的是确定在南北气候梯度从湿润到半干旱的每个含水层中动员溶解地下水As和F的水文和地球化学过程。综合化学分析了2002年至2022年间从534口井中采集的1164个水样，并在德克萨斯州水资源开发委员会（TWDB）的公共数据库中进行了报告。通过观察As和F与土地利用和地质层的空间相关性，对其地表和地质来源进行了检验。多变量分析表明，在北部和中部气候区，As与溶解铁（Fe）和/或锰（Mn）共变，而F与碳酸氢盐（HCO3）、钠（Na）和ph共变。在南部气候区，As和F与钒(V)共变。利用地球化学图和化学计量逆模型分析了产生As和F的可能化学反应。各流道均有明显的硅酸盐水解和阳离子交换溶解产物。通过阳离子交换从溶液中去除Ca驱动方解石和萤石溶解，推断这是北部和中部气候区地下水中F的主要来源，而铁和锰氧化物的还原性溶解释放溶解的As。砷和F主要通过卡塔胡拉组火山灰层的硅酸盐风化作用释放到南部含水层。该研究揭示了在650公里宽的不同地质和气候区域内砷和氟释放的变化驱动因素。了解这些驱动因素对于决定避免消耗受污染地下水或通过土地利用或地下水开采使污染恶化的最佳策略非常重要。

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来源期刊

Applied Geochemistry 地学-地球化学与地球物理

CiteScore

6.10

自引率

8.80%

发文量

272

审稿时长

65 days

期刊介绍： Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application. Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.