College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
Environ Sci Pollut Res Int. 2022 Oct;29(47):71150-71164. doi: 10.1007/s11356-022-20685-1. Epub 2022 May 20.
Groundwater is an important resource of water in arid and semi-arid agricultural regions. Thus, identification of hydrogeochemical characters and the influence of geospatial variability and flow pooling are of significance on groundwater resources management and making irrigation decisions in salinized areas. The study specifically focused on the Hetao Irrigation District located in the semi-arid region of northern China. A total of 85 groundwater samples (42 from the upstream Shenwu Irrigation Area (SWIA), 43 from the downstream Wulate Irrigation Area (WLTIA)) were collected, and 15 water quality indexes were analyzed. Methods including mathematical statistics, Piper diagram, Gibbs model, forward succession model, and ionic rations were used to analyze the hydrochemical characteristics and evolution mechanisms, RSBC, PS, SAR, WQI were selected to evaluate water quality and irrigation suitability from the perspective of salt and alkali damage. Results showed that the groundwater of the study area is weakly alkaline, SWIA is mainly fresh water (47.62%), WLTIA is mainly brackish water (65.12%), and the hydrochemistry of the groundwater consists of Cl-Na type and Cl·SO-Ca·Mg. The solute content of downstream (WLTIA) is higher than that of upstream (SWIA), Na and Cl have obvious advantages in WLTIA, and they are the main contribution indicators of groundwater TDS in the study area. The groundwater is subjected to the ongoing influence of rock weathering, ions exchange, and evaporate crystallization Na mainly originates from the dissolution of evaporate salt rock and silicate rock, and Ca from the dissolution of gypsum and carbonate. The order of contribution of different rocks is evaporation rock > silicate rock > carbonate rock. Based on the classifications of sodium absorption ratio (SAR), residual sodium bicarbonate (RSBC), and potential salinity (PS), most of the groundwater samples are unsuitable for irrigating, and the groundwater quality of the SWIA is better than that of the WLTIA.
地下水是干旱半干旱农业区的重要水资源。因此，识别水文地球化学特征以及地理空间变异性和水流汇集的影响，对于管理地下水资源和在盐渍化地区做出灌溉决策具有重要意义。本研究专门针对位于中国北方半干旱地区的河套灌区。共采集了 85 个地下水样本（42 个来自上游神府灌区（SWIA），43 个来自下游乌兰套海灌区（WLTIA）），分析了 15 个水质指标。采用数学统计、Piper 图、Gibbs 模型、正向演替模型和离子比等方法分析了水文地球化学特征和演化机制，从盐碱性损害的角度，选择 RSBC、PS、SAR 和 WQI 来评价水质和灌溉适宜性。结果表明，研究区地下水呈弱碱性，SWIA 主要为淡水（47.62%），WLTIA 主要为微咸水（65.12%），地下水水化学类型为 Cl-Na 型和 Cl·SO-Ca·Mg。下游（WLTIA）的溶质含量高于上游（SWIA），Na 和 Cl 在 WLTIA 中具有明显优势，是研究区地下水 TDS 的主要贡献指标。地下水受到岩石风化、离子交换和蒸发结晶的持续影响。Na 主要来源于蒸发盐岩和硅酸盐岩的溶解，Ca 来源于石膏和碳酸盐的溶解。不同岩石的贡献顺序为蒸发岩 > 硅酸盐岩 > 碳酸盐岩。根据钠吸收比（SAR）、剩余碳酸氢钠（RSBC）和潜在盐度（PS）的分类，大多数地下水样本不适宜灌溉，SWIA 的地下水水质优于 WLTIA。
