Chloride and metals in oil and gas co-produced wastewaters (often referred to as brines) are commonly perceived as contaminant hazards for biota. Amphibian abundance in the Prairie Pothole Region affected by historic oil and gas co-produced wastewaters was lower in wetlands with high concentrations of chloride indicating an actual contaminant hazard. Metals detected in sediments and amphibian tissues represent an additional potential stressor. However, in this study most of the metals detected in sediments and amphibian tissues were not directly linked with the higher chloride concentrations, indicating that they originated from other sources and could not identified as actual contaminant hazard.
Energy production is a national priority that has been addressed in part through rapid increases in domestic oil and gas production. During resource extraction of oil and gas, brines is rich in chloride and other major ions, metals, and other chemicals, are co-produced. The Williston Basin, one of North America's largest oil production areas, overlaps the Prairie Pothole Region, an area of small, shallow, isolated wetlands that offers important habitat for aquatic species and migratory birds. Co-produced wastewaters, resulting from spills or historical oil and gas extraction disposal practices, persist in some of the wetlands, resulting in altered water and sediment chemistry. Because the brines from the Williston Basin generated during oil and gas production can contain high levels of chloride, it is often the primary element of concern for biological effects.
Although the effects of brines in general, and chloride specifically, on amphibians have been documented in wetlands affected by runoff of road salts in urban areas, there is little information about effects on resident wildlife including amphibians in wetlands near oil and gas production. Amphibians were chosen as the focus of the study because their populations are declining worldwide, and they are sensitive to changes in the water and sediment chemistry owing to their permeable skin. Understanding the effects of multiple stressors on amphibian survival is important to determine if mitigation or restoration is needed, and if it is needed, to prioritize strategies to protect wildlife health to continue sustainable energy development.
Therefore, U.S. Geological Survey (USGS) Energy Science Team and Amphibian Research and Monitoring Initiative scientists completed field studies to determine if the larval amphibian abundance of boreal chorus frogs (Pseudacris maculata), barred tiger salamanders (Ambystoma mavortium), and northern leopard frogs (Lithobates [Rana] pipiens) were related to two potential stressors: chloride concentrations in wetlands affected by historic discharges of oil and gas co-produced wastewaters and metals concentrations in amphibian tissues and wetland sediments.
Field studies were completed during 2015 to 2017 at 33 freshwater wetlands primarily affected by historic disposal of oil and gas wastewaters in the Prairie Pothole Region. Few (less than 5 percent) of the surface waters in the region are naturally dominated by chloride, so scientists were able to identify wetlands affected by historic oil and gas wastewaters by measuring chloride concentrations and specific conductance, and by reviewing historic and current well locations.
Chloride concentrations in the wetlands sampled ranged from 2.6 to 17,150 milligrams per liter, and 20 of the 33 wetlands had mean concentrations that exceeded 230 milligrams per liter, which is the U.S. Environmental Protection Agency’s Aquatic Life Criteria for chronic chloride toxicity. Amphibian abundance was lower in wetlands with greater chloride concentrations for all three species studied. The abundance of boreal chorus frog larvae declined most rapidly in response to increased chloride concentrations, followed by the northern leopard frog and barred tiger salamander, highlighting differences in species sensitivity.
Metals have also been identified as co-contaminants in wastewaters and are perceived hazards for biota, but in this study most of the metals detected in sediments and amphibian tissues were not directly linked with the higher chloride concentrations, indicating that they originated from other sources. Exceptions include sodium and strontium in wetland sediments, and selenium and vanadium in amphibian tissues. Metal tissue concentrations were higher in tadpoles that graze compared to predatory salamanders, indicating frequent contact with the sediments could lead to greater ingestion of metal-laden materials. Metals in the sediments and tissues represent an additional potential stressor, other than elevated chloride concentrations from oil and gas brines that may have influenced amphibian abundance and survival.
The results of this combination of studies provide information to understand some of the many possible stressors, including chloride and metals, that may affect resident amphibians in the environment. Questions remain about the combined effects of pathogens, other contaminants, and physical stressors on amphibians and other aquatic organisms. The Energy Science Team of the USGS continues to address these and other questions related to toxicant exposure.
The USGS Toxic Substances Hydrology and Contaminant Biology combined programs, as well as the Amphibian Research and Monitoring Initiative, supported these integrated science studies.
Below are other science projects associated with this project.
Ecologically-Driven Exposure Pathways Science Team
Trace Levels of Organic Chemicals Limited to Local Reaches of a Stream near an Oil and Gas Wastewater Disposal Facility
Examining Shifts in Stream Microbial Communities Exposed to Oil and Gas Wastewaters
Understanding Pathways of Unconventional Oil and Gas Produced Water Spills in the Environment
Indication of Unconventional Oil and Gas Wastewaters Found in Local Surface Waters
Below are data or web applications associated with this project.
Chloride in water, metals in sediment and amphibian tissues and amphibian capture information from wetlands in the Williston Basin of Montana and North Dakota, 2015-2017
Widespread Legacy Brine Contamination from Oil Shales Reduces Survival of Chorus Frog Larvae-Data
Below are publications associated with this project.
Associations between environmental pollutants and larval amphibians in wetlands contaminated by energy-related brines are potentially mediated by feeding traits
Effects of persistent energy-related brine contamination on amphibian abundance in national wildlife refuge wetlands
Widespread legacy brine contamination from oil production reduces survival of chorus frog larvae
- Overview
Chloride and metals in oil and gas co-produced wastewaters (often referred to as brines) are commonly perceived as contaminant hazards for biota. Amphibian abundance in the Prairie Pothole Region affected by historic oil and gas co-produced wastewaters was lower in wetlands with high concentrations of chloride indicating an actual contaminant hazard. Metals detected in sediments and amphibian tissues represent an additional potential stressor. However, in this study most of the metals detected in sediments and amphibian tissues were not directly linked with the higher chloride concentrations, indicating that they originated from other sources and could not identified as actual contaminant hazard.
Two USGS scientists collecting surface water samples in the Rabenberg Waterfowl Protection Area, Montana, as part of an effort to study if historic oil and gas production in the Williston Basin has impacted amphibians in the Prairie Pothole Region. Energy production is a national priority that has been addressed in part through rapid increases in domestic oil and gas production. During resource extraction of oil and gas, brines is rich in chloride and other major ions, metals, and other chemicals, are co-produced. The Williston Basin, one of North America's largest oil production areas, overlaps the Prairie Pothole Region, an area of small, shallow, isolated wetlands that offers important habitat for aquatic species and migratory birds. Co-produced wastewaters, resulting from spills or historical oil and gas extraction disposal practices, persist in some of the wetlands, resulting in altered water and sediment chemistry. Because the brines from the Williston Basin generated during oil and gas production can contain high levels of chloride, it is often the primary element of concern for biological effects.
Although the effects of brines in general, and chloride specifically, on amphibians have been documented in wetlands affected by runoff of road salts in urban areas, there is little information about effects on resident wildlife including amphibians in wetlands near oil and gas production. Amphibians were chosen as the focus of the study because their populations are declining worldwide, and they are sensitive to changes in the water and sediment chemistry owing to their permeable skin. Understanding the effects of multiple stressors on amphibian survival is important to determine if mitigation or restoration is needed, and if it is needed, to prioritize strategies to protect wildlife health to continue sustainable energy development.
Therefore, U.S. Geological Survey (USGS) Energy Science Team and Amphibian Research and Monitoring Initiative scientists completed field studies to determine if the larval amphibian abundance of boreal chorus frogs (Pseudacris maculata), barred tiger salamanders (Ambystoma mavortium), and northern leopard frogs (Lithobates [Rana] pipiens) were related to two potential stressors: chloride concentrations in wetlands affected by historic discharges of oil and gas co-produced wastewaters and metals concentrations in amphibian tissues and wetland sediments.
Field studies were completed during 2015 to 2017 at 33 freshwater wetlands primarily affected by historic disposal of oil and gas wastewaters in the Prairie Pothole Region. Few (less than 5 percent) of the surface waters in the region are naturally dominated by chloride, so scientists were able to identify wetlands affected by historic oil and gas wastewaters by measuring chloride concentrations and specific conductance, and by reviewing historic and current well locations.
Sources/Usage: Public Domain. Visit Media to see details.USGS scientists collected amphibians as part of an effort to study if historic oil and gas production in the Williston Basin has affected amphibians in the Prairie Pothole Region. This photograph shows a larval leopard frog (bottom) and a larval boreal chorus frog (top) that are two of the amphibian grazers collected from a wetland near Lostwood National Wildlife Refuge, North Dakota. Chloride concentrations in the wetlands sampled ranged from 2.6 to 17,150 milligrams per liter, and 20 of the 33 wetlands had mean concentrations that exceeded 230 milligrams per liter, which is the U.S. Environmental Protection Agency’s Aquatic Life Criteria for chronic chloride toxicity. Amphibian abundance was lower in wetlands with greater chloride concentrations for all three species studied. The abundance of boreal chorus frog larvae declined most rapidly in response to increased chloride concentrations, followed by the northern leopard frog and barred tiger salamander, highlighting differences in species sensitivity.
Metals have also been identified as co-contaminants in wastewaters and are perceived hazards for biota, but in this study most of the metals detected in sediments and amphibian tissues were not directly linked with the higher chloride concentrations, indicating that they originated from other sources. Exceptions include sodium and strontium in wetland sediments, and selenium and vanadium in amphibian tissues. Metal tissue concentrations were higher in tadpoles that graze compared to predatory salamanders, indicating frequent contact with the sediments could lead to greater ingestion of metal-laden materials. Metals in the sediments and tissues represent an additional potential stressor, other than elevated chloride concentrations from oil and gas brines that may have influenced amphibian abundance and survival.
The results of this combination of studies provide information to understand some of the many possible stressors, including chloride and metals, that may affect resident amphibians in the environment. Questions remain about the combined effects of pathogens, other contaminants, and physical stressors on amphibians and other aquatic organisms. The Energy Science Team of the USGS continues to address these and other questions related to toxicant exposure.
The USGS Toxic Substances Hydrology and Contaminant Biology combined programs, as well as the Amphibian Research and Monitoring Initiative, supported these integrated science studies.
- Science
Below are other science projects associated with this project.
Ecologically-Driven Exposure Pathways Science Team
The Ecologically-Driven Exposure pathways team identifies internal and external pathways and processes that can alter exposure and toxicity of contaminants and pathogens to wildlife the environment. That information is used to distinguish actual health risks to fish and wildlife. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...Trace Levels of Organic Chemicals Limited to Local Reaches of a Stream near an Oil and Gas Wastewater Disposal Facility
Organic contaminants that were present in Wolf Creek near a wastewater disposal facility were not evident farther downstream where Wolf Creek enters the New River. Wolf Creek and the New River are used for drinking water and recreational purposes.Examining Shifts in Stream Microbial Communities Exposed to Oil and Gas Wastewaters
Shifts in the overall microbial community structure were present in stream sediments that contained chemicals associated with unconventional oil and gas wastewaters. This work is part of a long-term study designed to understand persistence of chemicals from oil and gas wastewaters in sediments and water and how those factors might be related to exposures and adverse health effects, if any, on...Understanding Pathways of Unconventional Oil and Gas Produced Water Spills in the Environment
A new study measures the transport of chemicals associated with unconventional oil and gas (UOG) produced waters downstream from a pipeline leak in North Dakota. This work is part of a long-term study designed to understand chemical persistence in sediments and water and how those factors might be related to contaminant exposures and associated with adverse health effects, if any, on organisms.Indication of Unconventional Oil and Gas Wastewaters Found in Local Surface Waters
Evidence indicating the presence of wastewaters from unconventional oil and gas (UOG) production was found in surface waters and surficial sediments near an UOG disposal facility in West Virginia. - Data
Below are data or web applications associated with this project.
Chloride in water, metals in sediment and amphibian tissues and amphibian capture information from wetlands in the Williston Basin of Montana and North Dakota, 2015-2017
The data presented includes chloride concentration and specific conductance in surface water collected from 33 wetlands in the Williston Basin of Montana and North Dakota, 2015-2017 as well as count data for three species of amphibians captured at each wetland. Data also includes concentrations of metals in bed sediment and larval amphibians collected from 32 and 12 wetlands, respectively in 2015-Widespread Legacy Brine Contamination from Oil Shales Reduces Survival of Chorus Frog Larvae-Data
Advances in drilling technique have facilitated a rapid increase in hydrocarbon extraction from energy shales, including the Williston Basin in central North America. This area overlaps with the Prairie Pothole Region and greater than 35% of wetlands are less than or equal to 1 km from a petroleum-related well. Legacy practices often released saline co-produced waters (brines) that were chloride r - Publications
Below are publications associated with this project.
Associations between environmental pollutants and larval amphibians in wetlands contaminated by energy-related brines are potentially mediated by feeding traits
Energy production in the Williston Basin, located in the Prairie Pothole Region of central North America, has increased rapidly over the last several decades. Advances in recycling and disposal practices of saline wastewaters (brines) co-produced during energy production have reduced ecological risks, but spills still occur often and legacy practices of releasing brines into the environment causedEffects of persistent energy-related brine contamination on amphibian abundance in national wildlife refuge wetlands
To inform sustainable energy development, it is important to understand the ecological effects of historical and current production practices and the persistence of those effects. The Williston Basin is one of North America's largest oil production areas and overlaps the Prairie Pothole Region, an area densely populated with wetlands that provide important wildlife habitat. Although historical disWidespread legacy brine contamination from oil production reduces survival of chorus frog larvae
Advances in drilling techniques have facilitated a rapid increase in hydrocarbon extraction from energy shales, including the Williston Basin in central North America. This area overlaps with the Prairie Pothole Region, a region densely populated with wetlands that provide numerous ecosystem services. Historical (legacy) disposal practices often released saline co-produced waters (brines) with hig