Anthropogenic contamination of groundwater

Landfill leakage—Babylon, Long Island, New York, USA 

Reducing conditions within the leachate plume also cause metal mobility, particularly of manganese and iron. The plume near the landfill has a pH of 6.0-6.5 and is reducing (-50 mV), making Fe2+ stable (Box 5.4). The transition to oxidizing conditions down gradient in the aquifer allows solid iron oxides (e.g. FeOOH) to precipitate, dramatically, reducing the mobility of metals which co-precipitate with iron. 

This relatively inoffensive example illustrates the importance of redox conditions in contaminated groundwater. Worse scenarios are known where toxic chlorophenolic compounds in very alkaline groundwaters (pH 10) ionize to neg- 

In addition, leaking tanks at a chemical company are believed to have delivered benzene, methylene chloride (CH2CI2), toluene (C6H5CH3), xylene (C6H4(CH3)2) and aliphatic hydrocarbons (see Section 2.7) to the subsurface water. These toxic (some carcinogenic) chemicals vaporize in the cave atmosphere, collect at traps and then rise into homes in a similar way to petroleum fumes. 

The potential explosive/toxicity risk in Bowling Green has resulted in a number of evacuations of homes in the last 20 years. Remediation measures have 

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