黄淮海平原地下水化学演化特征、形成机制及其开发利用建议

Characteristics and driving mechanisms of evolution of groundwater chemistry in Huang-Huai-Hai Plain and its exploitation and utilization suggestions

【研究目的】地下水是保障黄淮海平原生产、生活所需的主要水资源之一。在人类活动的影响下,地下水环境恶化已成为制约社会经济发展和生态平衡的重要因素。深入探究地下水化学演化特征及其形成机制,可为地下水资源的合理开发利用提供重要参考依据。【研究方法】本文将黄淮海平原分为山前平原、中部平原、滨海平原三个水文地质单元,综合运用Piper三线图、Gibbs图、主成分分析等方法,研究了中国黄淮海平原的地下水化学特征及其形成机制。【研究结果】结果显示,从山前平原到中部平原再到滨海平原地下水中TDS含量逐渐升高,由淡水逐渐演化为微咸水、咸水、盐水、卤水;研究区地下水化学类型从山前平原的44种增至中部平原的74种,而后下降至滨海平原的22种;其中,山前平原地下水化学类型以HCO_(3)-Ca·Mg、HCO_(3)-Ca为主,主要受控于一个4因素模式,相比之下,中部平原和滨海平原地下水化学则分别受控于3因素模式。【结论】黄淮海平原地下水化学特征呈明显分带性,从山前平原到中部平原到滨海平原地下水化学类型由HCO_(3)型逐渐演化为HCO_(3)·SO_(4)型、HCO_(3)·Cl型、SO_(4)型、SO_(4)·Cl型,最终演化为Cl型水。研究区地下水化学在空间尺度上主要受控于多种自然因素(岩石风化、蒸发浓缩和阳离子交替吸附、海水入侵),其在时间尺度上明显受多种人类活动(地下水超采、土地利用变化、生活污水、化肥、动物粪便)的影响。针对山前平原至滨海平原各区不同的地下水化学特征及其人类活动影响,有针对性地提出了黄淮海平原地下水资源开发利用方面的管控建议。

This paper is the result of hydrogeological survy engineering.[Objective]Groundwater is one of the major water resources to supply water for the production and daily life of human activities in the Huang-Huai-Hai Plain(HP).The deterioration of groundwater environment has become an important factor restricting social and economic development and ecological balance at the conditions of human activities.Understanding the characteristics and driving mechanisms of evolution of groundwater chemistry can provide an important reference for the rational development and utilization of groundwater resources.[Methods]In this paper,the HP is divided into three hydrogeological units including piedmont plain,central plain,and coastal plain.The characteristics and driving mechanisms of evolution of groundwater chemistry in HP in China are studied by using Piper diagram,Gibbs diagram,and principal component analysis.[Results]Results showed that TDS concentrations in groundwater increased gradually from piedmont plain to coastal plain,and groundwater was evolved from freshwater to brine via brackish water and salt water.Groundwater in the study area was from 44 hydrochemical facies in the piedmont plain increased to 74 hydrochemical facies in the central plain,and then decreased to 22 hydrochemical facies in the coastal plain.Among them,the hydrochemical facies of groundwater in the piedmont plain were dominated by HCO_(3)-Ca·Mg and HCO_(3)-Ca,and was mainly controlled by a 4-factors model,by contrast,groundwater chemistry in the central and coastal plains was controlled by two 3-factors models,respectively.[Conclusions]The chemical characteristics of groundwater in the HP are obviously zonal,and the hydrochemical facies of groundwater from the piedmont plain to the coastal plain was evolved gradually from HCO_(3) facies to HCO_(3)·SO_(4) facies,HCO_(3)·Cl facies,SO_(4) facies,as well as SO_(4)·Cl facies,and finally convert to Cl facies.The groundwater chemistry in the study area is mainly controlled by a variety of natural factors such as rock weathering,evaporative concentration,cation alternate adsorption,and seawater intrusion on the spatial aspect,and is obviously affected by various human activities(e.g.,groundwater overexploitation,land use change,domestic sewage,fertilizers,and animal manure)on the time aspect.According to the different chemical characteristics of groundwater and the impact of human activities in the areas from piedmont plain to coastal plain,the management and control suggestions on the development and utilization of groundwater resources in the HP are put forward.