Abstract:
The Permian Basin, straddling New Mexico and Texas, is the largest oil and gas (OG) producing region in the United States. OG production yields large volumes of wastewaters that have complex chemistries, which 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, which resulted in ~4,000 barrels of fluids being released 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 unaffected (control) soils collected from the same site. Soil geochemistry across all dump sites differed from unaffected soils, 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 that communities in dump zones had lower alpha diversity compared to control sites. Subjecting a weighted UniFrac distance matrix to a permutational multivariate analysis of variance (PERMANOVA) revealed significant (p<0.01) variation between dump and control soil community structure. Shifts in the phylogenetic composition and potential function of microorganisms in dump-affected soils were also observed. Dump-affected soils showed an overwhelming increase in OTUs with halophilic capabilities, such as those affiliated with the Marinobacteraceae, Halomonadaceae, and Halobacteroidaceae, suggesting that the brine composition of the OG wastewater dumps were a strong selective pressure for microbial communities. Taxa with capabilities to metabolize hydrocarbons were also detected in the dump-affected soil communities. Overall, this study elucidates changes in arid soil geochemistry and microbial community dynamics due to OG wastewater exposure. Ultimately, we elucidate the potential role for microorganisms to serve as biological markers for, and their potential to naturally attenuate, OG wastewaters.
