ABSTRACT

A groundwater contaminant is defined by most regulatory agencies as any physical, chemical, biological, or radiological substance or matter in groundwater. The most prevalent human activities that cause groundwater contamination are waste disposal, storage and transportation of commercial materials, mining operations, agricultural operations, and other activities. This chapter discusses the principal sources and causes of groundwater contamination from these activities with regard to their occurrence and effects on groundwater quality. Waste disposal includes the disposal of liquid waste and solid waste. Groundwater contamination from the storage and transport of commercial materials results from leaking storage tanks and spills. Groundwater can be contaminated by the drainage from mines and by oil and gas mining operations. The use of fertilizers and pesticides in agricultural operations can contaminate groundwater. Fertilizers are the primary cause of groundwater contamination beneath agricultural lands. Interaquifer exchange and saltwater intrusion are two other human activities that cause groundwater contamination.