大规模开采条件下我国北方区域地下水水化学变化特征

本文在总结近些年来我国北方地下水水文地质调查成果的基础上,对大规模开采条件下我国北方主要盆地和平原地下水化学变化规律及其影响因素进行探讨。结果表明:在大规模开采地下水后,我国北方地下水水化学变化特征主要表现为:浅层地下水水化学类型向重碳酸型水转变,地下水硬度增高,且在地下水大规模开发利用时间比较早的山西盆地、华北平原和东北平原变化比较明显,在西北干旱地区并不明显;深层地下水水化学类型由重碳酸型水转变为其它类型,地下水矿化度增大,水质变差,且在新疆准噶尔盆地、山西盆地和华北平原及东北平原变化比较明显。同时在地下水强烈开采区的潜水和承压含水层及主要城市区的地下水水化学特征均表现为常量组分升高,矿化度增大,污染组分和污染程度增加。导致这些变化产生的原因主要是70年代以后地下水的大规模开发利用引起地下水流场发生变化和局部地区人类活动影响造成的污染物增加和不合理排放。

Evaluation of Hydrochemical Characteristics of Regional Groundwater Systems in Northern China under the Conditions of Large-scale Exploitation

Hydrochemical characteristics and its influencing factors of regional groundwater systems under the conditions of large-scale exploitation were discussed based on the data of groundwater resource investigation in Northern China. Results show that the water type of groundwater in shallow aquifers changed into bicarbonate type with increasing TDS, which was more significant in the Shanxi Basin, the Northern China Plain and the Northeastern China Plain than arid region of Northwestern China with earlier large scale development and utilization of groundwater. The water type of groundwater in deep aquifers changed from bicarbonate type with increasing TDS and pollutant, which was obvious in the Junggar Basin, the Shanxi Basin, the Northern China Plain and the Northeastern China Plain. Moreover, the major constituent, TDS and pollutants in groundwater all showed increasing trend in over-exploration area such as irrigated regions, saline groundwater regions and major urban areas. Changes of groundwater flow due to the over-exploration since 1970, increasing and unreasonable pollutant emissions by regional human activities were thought to be the main causes.