Publications by authors named "David D Harper"

A pipeline carrying unconventional oil and gas (OG) wastewater spilled approximately 11 million liters of wastewater into Blacktail Creek, North Dakota, USA. Flow of the mix of stream water and wastewater down the channel resulted in storage of contaminants in the hyporheic zone and along the banks, providing a long-term source of wastewater constituents to the stream. A multi-level investigation was used to assess the potential effects of oil and brine spills on aquatic life.

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Oil and gas extraction in the Prairie Pothole Region (PPR) of the northern USA has resulted in elevated chloride concentrations in ground and surface water due to widespread contamination with highly saline produced water, or brine. The toxicity of chloride is poorly understood in the high hardness waters characteristic of the region. We evaluated the toxicity of chloride to two endemic species, Daphnia magna (water flea) and Lemna gibba (duckweed), exposed in field-collected waters (hardness ~ 3000 mg/L as CaCO) and reconstituted waters (hardness 370 mg/L as CaCO) intended to mimic PPR background waters.

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Ecological restorations of contaminated sites balance the human and ecological risks of residual contamination with the benefits of ecological recovery and the return of lost ecological function and ecosystem services. Risk and recovery are interrelated dynamic conditions, changing as remediation and restoration activities progress through implementation into long-term management and ecosystem maturation. Monitoring restoration progress provides data critical to minimizing residual contaminant risk and uncertainty, while measuring ecological advancement toward recovery goals.

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Technological advances in hydraulic fracturing and horizontal drilling have led to the exploration and exploitation of shale oil and gas both nationally and internationally. Extensive development of shale resources has occurred within the United States over the past decade, yet full build out is not expected to occur for years. Moreover, countries across the globe have large shale resources and are beginning to explore extraction of these resources.

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Some tributaries in the Powder River Structural Basin, USA, were historically ephemeral, but now contain water year round as a result of discharge of coalbed natural gas (CBNG)-produced waters. This presented the opportunity to study field sites with 100% effluent water with elevated concentrations of sodium bicarbonate. In situ experiments, static renewal experiments performed simultaneously with in situ experiments, and static renewal experiments performed with site water in the laboratory demonstrated that CBNG-produced water reduces survival of fathead minnow (Pimephales promelas) and pallid sturgeon (Scaphirhynchus albus).

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Sodium bicarbonate (NaHCO3) is the principal salt in coal bed natural gas produced water from the Powder River Structural Basin, Wyoming, USA, and concentrations of up to 3000 mg NaHCO3/L have been documented at some locations. No adequate studies have been performed to assess the chronic effects of NaHCO3 exposure. The present study was initiated to investigate the chronic toxicity and define sublethal effects at the individual organism level to explain the mechanisms of NaHCO3 toxicity.

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Water produced during coal bed natural gas (CBNG) extraction in the Powder River Structural Basin of Wyoming and Montana (USA) may contain concentrations of sodium bicarbonate (NaHCO3) of more than 3000 mg/L. The authors evaluated the acute toxicity of NaHCO3, also expressed as bicarbonate (HCO3(-)), to 13 aquatic organisms. Of the 13 species tested, 7 had a median lethal concentration (LC50) less than 2000 mg/L NaHCO3, or 1300 mg/L HCO3(-).

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The Yankee Fork is a large tributary of the Salmon River located in central Idaho, USA, with an extensive history of placer and dredge-mining activities. Concentrations of selenium (Se) and mercury (Hg) in various aquatic trophic levels were measured in the Yankee Fork during 2001 and 2002. Various measurements of fish health were also performed.

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A history of hard-rock mining has resulted in elevated concentrations of heavy metals in Prickly Pear Creek (MT, USA). Remediation has improved water quality; however, dissolved zinc and cadmium concentrations still exceed U.S.

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Extrapolating results of laboratory bioassays to streams is difficult, because conditions such as temperature and dissolved metal concentrations can change substantially on diel time scales. Field bioassays conducted for 96 h in two mining-affected streams compared the survival of hatchery-raised, metal-naïve westslope cutthroat trout (Oncorhynchus clarki lewisi) exposed to dissolved (0.1-microm filtration) metal concentrations that either exhibited the diel variation observed in streams or were controlled at a constant value.

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To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S.

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Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout.

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This study was designed to determine fish health impairment of Chinook salmon (Oncorhynchus tshawytscha) exposed to chromium. Juvenile Chinook salmon were exposed to aqueous chromium concentrations (0-266 microgl(-1)) that have been documented in porewater from bottom sediments and in well waters near salmon spawning areas in the Columbia River in the northwestern United States. After Chinook salmon parr were exposed to 24 and 54 microg Crl(-1) for 105 days, neither growth nor survival of parr was affected.

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