Hydrogeochemical characteristics and water quality of Aji-Chay river, eastern catchment of Lake Urmia, Iran,Journal of Earth System Science

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Hydrogeochemical characteristics and water quality of Aji-Chay river, eastern catchment of Lake Urmia, Iran
Journal of Earth System Science ( IF 1.9 ) Pub Date : 2020-09-19 , DOI: 10.1007/s12040-020-01469-y
Morteza Safari , Ardeshir Hezarkhani , Seyyed Reza Mashhadi

Abstract

The Aji-Chay river is the most important river discharging into endangered Lake Urmia in NW of Iran. The present study investigates the hydrogeochemical characteristics and origin of dissolved ions in the Aji-Chay river and some of its tributaries passing through Tabriz plain which is located at the east side of Lake Urmia. For this purpose, 317 water samples were collected during 9 years (2005–2014) from four stations and clustered to nine groups using K-means algorithm. Major cations and anions were considered to distinguish the hydrogeochemical evolution of water. The Piper, Langelier–Ludwig and Stiff diagrams classified water samples into predominant Na–Cl endmember and Ca–HCO₃ only in the upstream zone. With respect to Gibbs diagrams, mineral saturation indices and geology of the area, water chemistry of the Aji-Chay river reflects that water–rock chemical interactions including dissolution/precipitation of carbonate and sulfate minerals known as dedolomitization and dissolution of evaporitic salts along the flow path are the dominant factors controlling the water chemistry; furthermore, evaporation, silicate weathering, and ion exchange reactions change the chemistry of water to some extent. Overall, water quality is evaluated as poor. Furthermore, intense halite dissolution increases Na concentration in water which in turn reduces its suitability for irrigation purposes.

Research Highlights

Hydrogeochemical characteristics of main branches of Aji-Chay river are examined through a long-term (9 years) sampling program; then, K-means algorithm is used to cluster the data into 9 groups
Mineral saturation indices based on the concentration of ionic components in the water were calculated using PHREEQC software at the same thermodynamic conditions of gathered samples
Several Indices and standard diagrams are utilized to delineate hydrochemical processes that dominate surface water and assess the influence of possible water-rock interactions on water chemistry
Dissolution/precipitation of carbonate and NaCl-bearing lithological units substantially influence the quality of water
The suitability of water is characterized as “poor” for irrigation purposes because of high Na concentration and salinity except in the upstream where lithology has not reduced the water quality

中文翻译：

伊朗乌尔米亚湖东部集水区Aji-Chay河的水文地球化学特征和水质

摘要

Aji-Chay河是排入伊朗西北部濒临灭绝的Urmia湖的最重要河流。本研究调查了Aji-Chay河及其部分支流经过位于Urmia湖东侧的Tabriz平原的水文地球化学特征和溶解离子的来源。为此，在9年内（2005-2014年）从四个站点收集了317个水样，并使用K-means算法将其分为9个组。主要阳离子和阴离子被认为可以区分水的水地球化学演化。Piper，Langelier-Ludwig和Stiff图将水样分为主要的Na-Cl端基和Ca-HCO _3。仅在上游区域。关于吉布斯图，该地区的矿物质饱和度指数和地质学，阿吉查伊河的水化学反应表明，水与岩石之间的化学相互作用包括碳酸盐和硫酸盐矿物的溶解/沉淀，这被称为去离子化作用和沿流向的蒸发盐的溶解路径是控制水化学的主要因素。此外，蒸发，硅酸盐风化和离子交换反应在一定程度上改变了水的化学性质。总体而言，水质被评为差。此外，强烈的盐酸盐溶解会增加水中的Na浓度，进而降低其在灌溉中的适用性。