Abstract: Impact of Lignite and Hydrocarbon Accumulations on ²²²Radon Concentrations in Drinking Water Supplies

Elichia A. Venso

Lignite and hydrocarbon accumulations are efficient uranium sinks, and ²²²Radon has been associated with the presence of hydrocarbon-trapping faults and salt domes. Lung exposure to this radioactive respiratory carcinogen can result upon the release of radon from domestic water during normal household activities. To determine if an association was present between elevated radon levels and factors affecting the distribution of ²³⁸Uranium and its decay products, 27 individual water wells and 48 public water systems of nine rural counties in and adjacent to an Texas Eocene Wilcox lignite belt were sampled and the water assayed. Radon levels in these water supplies ranged from <10 to 1359 pCi 1^-1.

Statistical analysis of radon concentrations and variables representing the presence of potential sinks was performed. A highly significant model (P<0.001) containing the predictor variables for lignite, faults, and salt domes explained 22.2% of the radon variation in groundwater supplies. Addition of a variable for distance to an oil or gas field also produced a highly significant model (P<0.001) that explained 21.3 % of radon variation. Mapping showed the highest radon concentrations were from lignite belt samples, which suggests that lignite may be a radionuclide source.

The proposed standard for radon in public drinking water supplies is 300 pCi 1^-1. Thus, the demonstrated association between elevated radon concentrations and petroleum fields and low-rank coal may provide an informational tool for decision-making with regard to drilling public and private domestic water wells in the Eastern United States.

AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York