Daily Question 2015.8.5 (EIA Discussion): 3 Wealth points for replies, plus 5 Wealth points for correct answers (single-choice question)

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Groundwater pollution caused by the infiltration of leachate resulting from the leaching of solid waste belongs to ( ) pollution. A. Intermittent infiltration type B. Continuous infiltration type C. Overflow type D. Runoff type Correct answer: A. Explanation: There are various ways in which groundwater can become polluted, which can generally be classified into four categories: ① Intermittent infiltration type. Atmospheric precipitation or other irrigation water carries pollutants through the unsaturated zone, periodically infiltrating into aquifers, with groundwater being the main source of contamination. Groundwater pollution caused by the infiltration of leachate resulting from the leaching of solid waste also falls into this category. ②Continuous infiltration type. Pollutants continuously seep into aquifers via water, primarily contaminating groundwater. Wastewater channels, wastewater ponds, wastewater infiltration wells, etc., as well as the continuous leakage into contaminated surface water bodies, cause groundwater pollution, which falls into this category. ③Overflow type. Pollutants are transferred from contaminated aquifers (or natural saline aquifers) to uncontaminated aquifers (or natural freshwater aquifers) through overflow. Pollutants contaminate groundwater and confined water either through the entire layer, or through windows where the formation ends, or through damaged well pipes. The extraction of groundwater changes the direction of flow, allowing contaminated phreatic water to enter uncontaminated confined water, which falls into this category. ④Runoff type. Pollutants enter aquifers through groundwater flow, contaminating phreatic or confined water. Pollutants that enter aquifers through underground karstic pores fall into this category.