ABSTRACT
This chapter deals with groundwater contamination, a critical environmental issue characterized by the introduction of harmful chemical substances or microorganisms into subsurface waters. Groundwater is highly susceptible to contamination due to its ability to dissolve a wide range of substances. The chapter discusses various contaminant transport processes, focusing on conservative and non-conservative transport mechanisms, as well as the impact of non-aqueous phase liquids on groundwater quality. It highlights the challenges in predicting and remediating subsurface contamination due to the complex nature of groundwater flow and the difficulties in accurately characterizing subsurface materials. Approximate equations for assessing contaminant fate and transport are introduced with example applications. Case studies are also presented, including the risk assessment of on-site sewage disposal systems and the remediation of Superfund sites. The chapter also addresses the significant threat of ocean saltwater intrusion into coastal aquifers, exacerbated by factors such as excessive groundwater pumping and rising sea levels.
