Abstract

Hydrogeochemical understanding of groundwater is essential for the effective management of groundwater. This study has been carried out to have concrete data for the seasonal variations in hydrogeochemistry of groundwater in central Tamilnadu forming a complex geological terrain with a varied lithology. A total of 244 groundwater samples were collected during four different seasons, viz, southwest monsoon (SWM), summer (SUM), postmonsoon (POM), and northeast monsoon (NEM) from bore wells. The physical parameters such as pH, temperature, TDS, ORP, humidity, and electrical conductivity (EC) were measured insitu, whereas major ions were analyzed in the lab adopting standard procedures. Overall, higher EC and NO₃ values were observed and exceeded the WHO permissible limit irrespective of seasons, except for NO₃ in SWM. Na and HCO₃ are the dominant cation and anion in the groundwater irrespective of seasons. The highest average values of Na (65.06 mg L⁻¹) and HCO₃ (350.75 mg L⁻¹) were noted during SWM. Statistical analysis was carried out to elucidate the hydrogeochemistry of the region. Initially, to understand the ionic relationship, correlation matrix was used followed by factor analysis for determination of major geochemical control and later factor scores were derived to understand the regional representations. An attempt has also been made to identify the samples influenced by multiple geochemical processes and to understand their spatial variation in the study period. Correlation of geochemical parameters reveals a excellent positive correlation between Ca and NO₃ in SUM, SWM, and NEM due to the dominant of anthropogenic sources and minor influence of weathering process. Strongly loaded factor scores are found to be mostly in the following order POM > NEM > SWM > SUM. Principal component analysis of different seasons indicates the interplay of natural weathering and anthropogenic factors. Overall, the predominant geochemical processes in this region, irrespective of seasons are weathering and, ion exchange and anthropogenic activities.

中文翻译：

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印度南部地下水质量恶化的季节性变化和污染源识别的化学计量分析。

摘要

对地下水的水文地球化学认识对于有效管理地下水至关重要。已经进行了这项研究，以提供有关泰米尔纳德邦中部地下水形成的复杂地质地形和岩性变化的地下水水文地球化学季节性变化的具体数据。在四个不同的季节（即西南季风（SWM），夏季（SUM），季风（POM）和东北季风（NEM））的四个不同季节收集了总共244个地下水样品。物理参数如pH，温度，TDS，ORP，湿度和电导率（EC）是在原位测量的，而主要离子在实验室中采用标准程序进行了分析。总体而言，观察到的EC和NO ₃值较高，并且超过了WHO允许的限值，与季节无关，除了NOSWM中的₃。与季节无关，Na和HCO ₃是地下水中的主要阳离子和阴离子。Na（65.06 mg L ^-1）和HCO ₃（350.75 mg L ^-1）的最高平均值）已在SWM期间注意到。进行了统计分析，以阐明该地区的水文地球化学。最初，为了了解离子之间的关系，先使用相关矩阵，然后进行因子分析来确定主要的地球化学控制方法，然后再导出因子得分以了解区域表示。还尝试确定受多种地球化学过程影响的样品，并了解其在研究期间的空间变化。地球化学参数的相关性揭示了Ca和NO ₃之间极好的正相关性在SUM，SWM和NEM中，由于人为来源的占主导地位以及风化过程的影响较小。发现强负载因子得分主要按以下顺序排列：POM> NEM> SWM> SUM。不同季节的主成分分析表明自然风化和人为因素的相互作用。总体而言，该地区的主要地球化学过程与季节无关，是风化和离子交换以及人为活动。