Department of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL, UK.
Department of Earth and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL, UK.
Environ Pollut. 2023 Jun 15;327:121626. doi: 10.1016/j.envpol.2023.121626. Epub 2023 Apr 11.
The presence and distribution of emerging organic contaminants (EOCs) in freshwater environments is a key issue in India and globally, particularly due to ecotoxicological and potential antimicrobial resistance concerns. Here we have investigated the composition and spatial distribution of EOCs in surface water along a ∼500 km segment of the iconic River Ganges (Ganga) and key tributaries in the middle Gangetic Plain of Northern India. Using a broad screening approach, in 11 surface water samples, we identified 51 EOCs, comprising of pharmaceuticals, agrochemicals, lifestyle and industrial chemicals. Whilst the majority of EOCs detected were a mixture of pharmaceuticals and agrochemicals, lifestyle chemicals (and particularly sucralose) occurred at the highest concentrations. Ten of the EOCs detected are priority compounds (e.g. sulfamethoxazole, diuron, atrazine, chlorpyrifos, perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate, thiamethoxam, imidacloprid, clothianidin and diclofenac). In almost 50% of water samples, sulfamethoxazole concentrations exceeded predicted no-effect concentrations (PNECs) for ecological toxicity. A significant downstream reduction in EOCs was observed along the River Ganga between Varanasi (Uttar Pradesh) and Begusarai (Bihar), likely reflecting dilution effects associated with three major tributaries, all with considerably lower EOC concentrations than the main Ganga channel. Sorption and/or redox controls were observed for some compounds (e.g. clopidol), as well as a relatively high degree of mixing of EOCs within the river. We discuss the environmental relevance of the persistence of several parent compounds (notably atrazine, carbamazepine, metribuzin and fipronil) and associated transformation products. Associations between EOCs and other hydrochemical parameters including excitation emission matrix (EEM) fluorescence indicated positive, significant, and compound-specific correlations between EOCs and tryptophan-, fulvic- and humic-like fluorescence. This study expands the baseline characterization of EOCs in Indian surface water and contributes to an improved understanding of the potential sources and controls on EOC distribution in the River Ganga and other large river systems.
新兴有机污染物（EOCs）在淡水中的存在和分布是印度和全球的一个关键问题，特别是由于其具有生态毒性和可能的抗微生物耐药性问题。在这里，我们调查了沿印度北部恒河（Ganges）标志性河流及其主要支流约 500 公里长的河段地表水的 EOC 组成和空间分布。我们使用广泛的筛选方法，在 11 个地表水样本中，共鉴定出 51 种 EOCs，包括药物、农药、生活方式化学品和工业化学品。虽然检测到的大多数 EOCs 是药物和农药的混合物，但生活方式化学品（尤其是三氯蔗糖）的浓度最高。在所检测到的 10 种 EOC 中，有 10 种是优先化合物（例如磺胺甲恶唑、敌草隆、莠去津、毒死蜱、全氟辛烷磺酸（PFOS）、全氟丁烷磺酸、噻虫嗪、氯吡虫啉、噻虫胺和双氯芬酸）。在近 50%的水样中，磺胺甲恶唑的浓度超过了对生态毒性的预测无影响浓度（PNEC）。在恒河从瓦拉纳西（北方邦）到贝古萨赖（比哈尔邦）的下游，EOC 浓度显著降低，这可能反映了与三条主要支流相关的稀释效应，这三条支流的 EOC 浓度均明显低于恒河干流。观察到一些化合物（如氯丙醇）存在吸附和/或氧化还原控制，以及河流中 EOC 混合程度较高。我们讨论了一些母体化合物（特别是莠去津、卡马西平、甲草胺和氟虫腈）及其相关转化产物持续存在的环境相关性。EOCs 与其他水化学参数（包括激发发射矩阵（EEM）荧光）之间的关联表明，EOCs 与色氨酸、富里酸和腐殖酸样荧光之间存在正相关、显著且化合物特异性的相关性。这项研究扩展了印度地表水 EOCs 的基线特征，有助于更好地了解恒河和其他大河系统中 EOC 分布的潜在来源和控制因素。
