Pollution source identification methods and remediation technologies of groundwater: A review

Groundwater is an important source of drinking water.Groundwater pollution severely endangers drinking water safety and sustainable social development.In the case of groundwater pollution,the top priority is to identify pollution sources,and accurate information on pollution sources is the premise of efficient remediation.Then,an appropriate pollution remediation scheme should be developed according to information on pollution sources,site conditions,and economic costs.The methods for identifying pollution sources mainly include geophysical exploration,geochemistry,isotopic tracing,and numerical modeling.Among these identification methods,only the numerical modeling can recognize various information on pollution sources,while other methods can only identify a certain aspect of pollution sources.The remediation technologies of groundwater can be divided into in-situ and ex-situ remediation technologies according to the remediation location.The in-situ remediation technologies enjoy low costs and a wide remediation range,but their remediation performance is prone to be affected by environmental conditions and cause secondary pollution.The ex-situ remediation technologies boast high remediation efficiency,high processing capacity,and high treatment concentration but suffer high costs.Different methods for pollution source identification and remediation technologies are applicable to different conditions.To achieve the expected identification and remediation results,it is feasible to combine several methods and technologies according to the actual hydrogeological conditions of contaminated sites and the nature of pollutants.Additionally,detailed knowledge about the hydrogeological conditions and stratigraphic structure of the contaminated site is the basis of all work regardless of the adopted identification methods or remediation technologies.

Critical issues in the characteristics and assessment of China's water resources

This study provides a comprehensive analysis of the concepts and assessment processes of water resources in China,focusing on the characteristics of water resources and variations in water cycle fluxes.It reveals that the distribution of water resources in China is uneven,with more south and less north,and human activities have led to a decline in water resources,particularly in northern arid and semi-arid regions.Further analysis shows that duplicated measurements of surface water and groundwater significantly affect water balance calculation and water resource assessments,serving as a crucial factor guiding water resource development and utilization.The study also finds that consistency correction of runoff series is insufficient to meet the requirements of accurate water resource assessment.It is urgent to strengthen fundamental research in hydrology and hydrogeology,and to establish a dynamic assessment system for the efficient management and rational use of surface water and groundwater in the current changing environment.

Environmental Effect Caused by Over-exploitation of Deep Groundwater in North China

Based on the formation and development analysis of the environmental geological disaster of land subsidence, earth fissures and other geological disasters in the North China,it showed these disasters caused a very serious problem in some areas of the North China, such as the deep groundwater exploitation cone, which is accumulated with great damage and loss and is hard to be controlled, therefore, great attention should be paid. It is considered that the formation of the deep groundwater cone is the root of various geological environmental problems, and the groundwater cone recovery is the key to solve other environmental problems.