UNCONVENTIONAL OIL AND GAS (UOG) WASTEWATER SPILLS: PERSISTENCE OF CONTAMINANTS AND ENVIRONMENTAL HEALTH IMPLICATIONS
Water and sediment samples were collected, and in situ bioassays were conducted, along a 44 km reach between the spill and the Missouri River in Feb and June 2015 and June 2016, to assess potential impacts from the spill. Wastewater in the ruptured pipeline contained 16.2 mg/L Ba and > 1,000 mg/L Sr. Samples collected in June 2015, indicate presence of UOG-wastewater markers and biological impacts in the river. These results document the persistence of geochemical alterations six months post spill. Fish bioassays conducted in June, 2015, demonstrated 97.5% mortality at 7.1 km downstream from the spill.
Alterations in sediment microbial communities downstream from the spill were observed in February 2015. Labile Ba and Sr concentrations extracted from sediments collected in June 2015 were higher downstream from the spill site than upstream. Radium concentrations in sediment downstream from the spill site (approx. 10 dpm/g) were up to 5 times the background concentrations. Ra and Sr isotope ratios in sediment downstream from the spill site resemble the radiogenic signatures from the pipeline and support the conclusion that elevated Ra and Sr concentrations reflect input from the spilled wastewater brine.
Experiments with an aquatic model invertebrate, the freshwater snail Lymnaea stagnalis, showed aqueous Ba is bioavailable and thus will bioaccumulate. Ba has deleterious effects on aquatic organisms and humans and a similar reactivity to Ra, providing insight into Ra pathways through the food chain. Partitioning of elements from the wastewater spill onto sediment limits aqueous transport but could provide a long-term source to aquatic ecosystems.