Scientists from the Department of Geosciences at Virginia Tech and the US Geological Survey have found that the natural breakdown of petroleum hydrocarbons underground, such as from petroleum spills or from fracking wastewater, can promote the chemical release of naturally occurring arsenic into groundwater. Normally arsenic is tightly bound to soils and presents no environmental or health risk but the metabolization of carbon–rich petroleum by microbes in anoxic (low oxygen) conditions can cause the release of the arsenic into groundwater flows. The article provides information on the likely chemical processes involved.

Fortunately the arsenic may be readsorbed by contact with downstream soils but the researchers theorize that once released the arsenic may be much more easily made soluble by other chemistry going on in the soil layers. The research found arsenic concentrations associated with a hydrocarbon plume of up to 23 times the current drinking water standard.

Arsenic is known to be toxic and is a powerful carcinogen associated with numerous forms of skin, bladder, and lung cancer. It is a common and problematic contaminant of drinking water in several regions of the world.

An abstract of the research article, published in the journal Groundwater, and a link to the full article, fee or subscription required, is available at http://onlinelibrary.wiley.com/doi/10.1111/gwat.12316/abstract