Fluoride (F^–) pollution in groundwater of the Older Alluvial Plain (OAP) of Delhi has been reported as a major problem. About 34% of the groundwater samples collected for this study had F^– level beyond the permissible limit; with F^– concentration in the range of 0.14–3.15 mg/L (average 1.20 mg/L). In this context, this article for the first time attempts on the genesis of major ions chemistry and F^– pollution in groundwater of OAP Delhi by going beyond the statistical analysis to sediment geochemistry, chemical weathering processes and understanding of the processes using stable environmental isotopes (²H and ¹⁸O). The XRD of the OAP sediments revealed the dominance of fluor-biotite, albite, calcite, quartz, and chlorite. Whereas, the separated clay revealed the dominance of chlorite, kaolinite, and illite minerals. The saturation index (SI) values indicated that the groundwater chemistry is in the process of further F^– enrichment by way of sediment groundwater interaction. With the given mineralogy of the sediments, the dominance of major ions like Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^– and F^– has been attributed to chemical weathering of biotites, phlogopites, albite, and calcite during sediment–water interaction. While the dominance of SO₄^2– has been attributed to anthropogenic sources and confirmed by its association with heavier stable isotopes of hydrogen (δ²H: −50.44 to −40.02‰) and oxygen (δ¹⁸O: −7.19 to −5.62‰) indicating evaporative enrichment during isotopic fractionation.

据报道，德里的旧冲积平原（OAP）地下水中的氟化物（F ^–）污染是一个主要问题。收集本研究地下水样品的约34％为F ^-超出允许极限水平; F ^–浓度在0.14–3.15 mg / L范围内（平均1.20 mg / L）。在此背景下，本文对主要离子化学和F的起源第一次尝试^-通过超越统计分析沉积物地球化学，化学风化过程和使用稳定的环境同位素的过程的理解（在OAP德里的地下水污染² H和¹⁸O）。OAP沉积物的X射线衍射揭示了氟黑云母，钠长石，方解石，石英和绿泥石的优势。而分离出的粘土则显示出绿泥石，高岭石和伊利石矿物的优势。饱和指数（SI）值表明，地下水化学正在进一步F中的过程^-通过沉积物地下水相互作用的方式富集。随着沉积物的给定的矿物学，主要离子如Na的主导地位⁺，K ⁺，Mg的²⁺，钙²⁺，氯^-和F ^-已沉淀期间被归因于黑云母，金云母，钠长石的化学风化和方解石–水的相互作用。虽然SO ₄ ²占主导地位已被归因于人为来源，并确认由它的关联用氢气（较重稳定同位素δ ² H：-50.44至-40.02‰）和氧（δ ¹⁸ ○：-7.19至-5.62‰）表示同位素分馏过程中蒸发浓缩。