Naturally-Occurring Radioactive Materials (NORM) Associated with Unconventional Drilling for Shale Gas. In: Drogos DL, editor. Hydraulic Fracturing: Environmental Issues. Washington: American Chemical Society; 2015. pp. 89-128. [DOI: 10.1021/bk-2015-1216.ch004]

Sources of Radium Accumulation in Stream Sediments near Disposal Sites in Pennsylvania: Implications for Disposal of Conventional Oil and Gas Wastewater

In Pennsylvania, Appalachian oil and gas wastewaters (OGW) are permitted for release to surface waters after some treatment by centralized waste treatment (CWT) facilities. While this practice was largely discontinued in 2011 for unconventional Marcellus OGW at facilities permitted to release high salinity effluents, it continues for conventional OGW. This study aimed to evaluate the environmental implications of the policy allowing the disposal of conventional OGW. We collected stream sediments from three disposal sites receiving treated OGW between 2014 and 2017 and measured ²²⁸Ra, ²²⁶Ra, and their decay products, ²²⁸Th and ²¹⁰Pb, respectively. We consistently found elevated activities of ²²⁸Ra and ²²⁶Ra in stream sediments in the vicinity of the outfall (total Ra = 90-25,000 Bq/kg) compared to upstream sediments (20-80 Bq/kg). In 2015 and 2017, ²²⁸Th/²²⁸Ra activity ratios in sediments from two disposal sites were relatively low (0.2-0.7), indicating that a portion of the Ra has accumulated in the sediments in recent (<3) years, when no unconventional Marcellus OGW was reportedly discharged. ²²⁸Ra/²²⁶Ra activity ratios were also higher than what would be expected solely from disposal of low ²²⁸Ra/²²⁶Ra Marcellus OGW. Based on these variations, we concluded that recent disposal of treated conventional OGW is the source of high Ra in stream sediments at CWT facility disposal sites. Consequently, policies pertaining to the disposal of only unconventional fluids are not adequate in preventing radioactive contamination in sediments at disposal sites, and the permission to release treated Ra-rich conventional OGW through CWT facilities should be reconsidered.

Polonium-210 accumulates in a lake receiving coal mine discharges-anthropogenic or natural?

Coal is an integral part of global energy production; however, coal mining is associated with numerous environmental health impacts. It is well documented that coal-mine waste can contaminate the environment with naturally-occurring radionuclides from the uranium-238 (²³⁸U) decay series. However, the behavior of the final radionuclide in the ²³⁸U-series, i.e., polonium-210 (²¹⁰Po) arising from coal-mine waste-water discharge is largely unexplored. Here, results of a year-long (2014-2015) field study, in which the concentrations of ²¹⁰Po in sediments and surface water of a lake that receives coal-mine waste-water discharge in West Virginia are presented. Initial measurements identified levels of ²¹⁰Po in the lake sediments that were in excess of that which could be attributed to ambient U-series parent radionuclides; and were indicative of discharge site contamination of the lake ecosystem. However, control sediment obtained from a similar lake system in Iowa (an area with no coal mining or unconventional drilling) suggests that the levels of ²¹⁰Po in the lake are a natural phenomenon; and are likely unrelated to waste-water treatment discharges. Elevated levels of ²¹⁰Po have been reported in lake bottom sediments previously, yet very little information is available on the radioecological implications of ²¹⁰Po accumulation in lake bottom sediments. The findings of this study suggest that (Monthly Energy Review, 2016) the natural accumulation and retention of ²¹⁰Po in lake sediments may be a greater than previously considered (Chadwick et al., 2013) careful selection of control sites is important to prevent the inappropriate attribution of elevated levels of NORM in lake bottom ecosystems to industrial sources; and (Van Hook, 1979) further investigation of the source-terms and potential impacts on elevated ²¹⁰Po in lake-sediment ecosystems is warranted.