EFFECTS OF PERMIAN BASIN OIL AND GAS WASTEWATER DUMPING ON SOIL MICROBIAL COMMUNITIES

The Permian Basin, straddling New Mexico and Texas, is one of the most productive oil and gas (OG) provinces in the United States. OG production yields large volumes of wastewater that have complex chemistries. These OG wastewaters pose unknown environmental health risks, particularly in the case of accidental or intentional releases. Starting in November 2017, at least 39 illegal dumps of OG wastewater were identified in southeastern New Mexico, part of the Permian Basin, releasing ~4,000 barrels of fluid onto desert soils. To evaluate the impacts of these releases, we analyzed changes in soil geochemistry and microbial community structure at 5 sites by comparing soils from within OG wastewater dump-affected zones to corresponding unaffected (control) soils. Soil geochemistry for all dump samples differed from unaffected samples, reflecting the residual salts and hydrocarbons left behind by the OG wastewater release (e.g., enriched in sodium (Na), chloride (Cl), and bromide (Br)). Microbial community analysis, using Illumina 16S iTag sequencing, revealed significant differences (p<0.01) between communities in dump and control zones. Further, soils from dump areas had significantly (p<0.01) lower alpha diversity, and differences in phylogenetic composition. Dump-affected soil samples showed an increase in taxa with halophilic capabilities, such as those affiliated with Marinobacteraceae, Halomonadaceae, and Halobacteroidaceae, suggesting that the high salinity of the dumped OG wastewater was a strong selective pressure for microbial communities. Taxa with capabilities to metabolize hydrocarbons were also detected in the dump-affected soil sample communities. Overall, this study elucidates changes in desert soil geochemistry and microbial community dynamics due to OG wastewater exposure.