Jimmy M. Clark

Aerobic biodegradation potential of endocrine‐disrupting chemicals in surface‐water sediment at Rocky Mountain National Park, USA

Endocrine-disrupting chemicals (EDCs) in surface water and bed sediment threaten the structure and function of aquatic ecosystems. In natural, remote, and protected surface-water environments where contaminant releases are sporadic, contaminant biodegradation is a fundamental driver of exposure concentration, timing, duration, and, thus, EDC ecological risk. Anthropogenic contaminants, including known and suspected EDCs, were detected in surface water and sediment collected from 2 streams and 2 lakes in Rocky Mountain National Park (Colorado, USA). The potential for aerobic EDC biodegradation was assessed in collected sediments using 6 (14) C-radiolabeled model compounds. Aerobic microbial mineralization of natural (estrone and 17β-estradiol) and synthetic (17α-ethinylestradiol) estrogen was significant at all sites. Bed sediment microbial communities in Rocky Mountain National Park also effectively degraded the xenoestrogens bisphenol-A and 4-nonylphenol. The same sediment samples exhibited little potential for aerobic biodegradation of triclocarban, however, illustrating the need to assess a wider range of contaminant compounds. The present studys results support recent concerns over the widespread environmental occurrence of carbanalide antibacterials, like triclocarban and triclosan, and suggest that backcountry use of products containing these compounds should be discouraged.

Spatial and temporal variation in microcystin occurrence in wadeable streams in the southeastern United States.

Despite historical observations of potential microcystin-producing cyanobacteria (including Leptolyngbya, Phormidium, Pseudoanabaena, and Anabaena species) in 74% of headwater streams in Alabama, Georgia, South Carolina, and North Carolina (USA) from 1993 to 2011, fluvial cyanotoxin occurrence has not been systematically assessed in the southeastern United States. To begin to address this data gap, a spatial reconnaissance of fluvial microcystin concentrations was conducted in 75 wadeable streams in the Piedmont region (southeastern USA) during June 2014. Microcystins were detected using enzyme-linked immunosorbent assay (limit = 0.10 µg/L) in 39% of the streams with mean, median, and maximum detected concentrations of 0.29 µg/L, 0.11 µg/L, and 3.2 µg/L, respectively. Significant (α = 0.05) correlations were observed between June 2014 microcystin concentrations and stream flow, total nitrogen to total phosphorus ratio, and water temperature; but each of these factors explained 38% or less of the variability in fluvial microcystins across the region. Temporal microcystin variability was assessed monthly through October 2014 in 5 of the streams where microcystins were observed in June and in 1 reference location; microcystins were repeatedly detected in all but the reference stream. Although microcystin concentrations in the present study did not exceed World Health Organization recreational guidance thresholds, their widespread occurrence demonstrates the need for further investigation of possible in-stream environmental health effects as well as potential impacts on downstream lakes and reservoirs. Environ Toxicol Chem 2016;35:2281-2287. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

Pre/post-closure assessment of groundwater pharmaceutical fate in a wastewater‑facility-impacted stream reach

Pharmaceutical contamination of contiguous groundwater is a substantial concern in wastewater-impacted streams, due to ubiquity in effluent, high aqueous mobility, designed bioactivity, and to effluent-driven hydraulic gradients. Wastewater treatment facility (WWTF) closures are rare environmental remediation events; offering unique insights into contaminant persistence, long-term wastewater impacts, and ecosystem recovery processes. The USGS conducted a combined pre/post-closure groundwater assessment adjacent to an effluent-impacted reach of Fourmile Creek, Ankeny, Iowa, USA. Higher surface-water concentrations, consistent surface-water to groundwater concentration gradients, and sustained groundwater detections tens of meters from the stream bank demonstrated the importance of WWTF effluent as the source of groundwater pharmaceuticals as well as the persistence of these contaminants under effluent-driven, pre-closure conditions. The number of analytes (110 total) detected in surface water decreased from 69 prior to closure down to 8 in the first post-closure sampling event approximately 30 d later, with a corresponding 2 order of magnitude decrease in the cumulative concentration of detected analytes. Post-closure cumulative concentrations of detected analytes were approximately 5 times higher in proximal groundwater than in surface water. About 40% of the 21 contaminants detected in a downstream groundwater transect immediately before WWTF closure exhibited rapid attenuation with estimated half-lives on the order of a few days; however, a comparable number exhibited no consistent attenuation during the year-long post-closure assessment. The results demonstrate the potential for effluent-impacted shallow groundwater systems to accumulate pharmaceutical contaminants and serve as long-term residual sources, further increasing the risk of adverse ecological effects in groundwater and the near-stream ecosystem.

Aerobic biodegradation potential of endocrine disrupting chemicals in surface-water sediment at Rocky Mountains National Park, USA

Endocrine-disrupting chemicals (EDCs) in surface water and bed sediment threaten the structure and function of aquatic ecosystems. In natural, remote, and protected surface-water environments where contaminant releases are sporadic, contaminant biodegradation is a fundamental driver of exposure concentration, timing, duration, and, thus, EDC ecological risk. Anthropogenic contaminants, including known and suspected EDCs, were detected in surface water and sediment collected from 2 streams and 2 lakes in Rocky Mountain National Park (Colorado, USA). The potential for aerobic EDC biodegradation was assessed in collected sediments using 6 (14) C-radiolabeled model compounds. Aerobic microbial mineralization of natural (estrone and 17β-estradiol) and synthetic (17α-ethinylestradiol) estrogen was significant at all sites. Bed sediment microbial communities in Rocky Mountain National Park also effectively degraded the xenoestrogens bisphenol-A and 4-nonylphenol. The same sediment samples exhibited little potential for aerobic biodegradation of triclocarban, however, illustrating the need to assess a wider range of contaminant compounds. The present studys results support recent concerns over the widespread environmental occurrence of carbanalide antibacterials, like triclocarban and triclosan, and suggest that backcountry use of products containing these compounds should be discouraged.

Widespread occurrence and potential for biodegradation of bioactive contaminants in Congaree National Park, USA

Organic contaminants with designed molecular bioactivity, such as pesticides and pharmaceuticals, originate from human and agricultural sources, occur frequently in surface waters, and threaten the structure and function of aquatic and terrestrial ecosystems. Congaree National Park in South Carolina (USA) is a vulnerable park unit due to its location downstream of multiple urban and agricultural contaminant sources and its hydrologic setting, being composed almost entirely of floodplain and aquatic environments. Seventy-two water and sediment samples were collected from 16 sites in Congaree National Park during 2013 to 2015, and analyzed for 199 and 81 targeted organic contaminants, respectively. More than half of these water and sediment analytes were not detected or potentially had natural sources. Pharmaceutical contaminants were detected (49 total) frequently in water throughout Congaree National Park, with higher detection frequencies and concentrations at Congaree and Wateree River sites, downstream from major urban areas. Forty-seven organic wastewater indicator chemicals were detected in water, and 36 were detected in sediment, of which approximately half are distinctly anthropogenic. Endogenous sterols and hormones, which may originate from humans or wildlife, were detected in water and sediment samples throughout Congaree National Park, but synthetic hormones were detected only once, suggesting a comparatively low risk of adverse impacts. Assessment of the biodegradation potentials of 8 14 C-radiolabeled model contaminants indicated poor potentials for some contaminants, particularly under anaerobic sediments conditions. Environ Toxicol Chem 2017;36:3045-3056. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Tidal flow dynamics and background fluorescence of the Atlantic Intracoastal Waterway in the vicinity of Sullivan’s Island and the Isle of Palms, South Carolina, 2011-12

To effectively plan site-specific studies to understand the connection between wastewater effluent and shellfish beds, data are needed concerning flow dynamics and background fluorescence in the Atlantic Intracoastal Waterway near the effluent outfalls on Sullivan’s Island and the Isle of Palms. Tidal flows were computed by the U.S. Geological Survey for three stations and longitudinal water-quality profiles were collected at high and low tide. Flows for the three U.S. Geological Survey stations, the Atlantic Intracoastal Waterway by the Isle of Palms Marina, the Atlantic Intracoastal Waterway by the Ben M. Sawyer Memorial Bridge at Sullivan’s Island, and Breach Inlet, were computed for the 53-day period from December 4, 2011, to January 26, 2012. The largest flows occurred at Breach Inlet and ranged from -58,600 cubic feet per second (ft3/s) toward the Atlantic Intracoastal Waterway to 63,300 ft3/s toward the Atlantic Ocean. Of the two stations on the Atlantic Intracoastal Waterway, the Sullivan’s Island station had the larger flows and ranged from -6,360 ft3/s to the southwest (toward Charleston Harbor) to 8,930 ft3/s to the northeast. Computed tidal flow at the Isle of Palms station ranged from -3,460 ft3/s toward the southwest to 6,410 ft3/s toward the northeast. The synoptic water-quality study showed that the stations were well mixed vertically and horizontally. All fluorescence measurements (recorded as rhodamine concentration) were below the accuracy of the sensor and the background fluorescence would not likely interfere with a dyetracer study. Introduction Proposed changes in water-quality limits for fecal coliform may have potential effects on the open shellfish beds (those beds where harvesting is allowed) near the effluent outfalls of the Sullivan’s Island and the Isle of Palms wastewater treatment plants (fig. 1). A number of alternative study approaches can be used to better understand the potential connections between wastewater effluent and the shellfish bed, including dye-tracer studies, sediment sampling for wastewater indicators, and thermal plume tracking. To effectively plan such studies, data are needed concerning the flow dynamics and background fluorescence of the Atlantic Intracoastal Waterway near the effluent outfalls on Sullivan’s Island and the Isle of Palms in South Carolina. Tidal flow dynamics of the Atlantic Intracoastal Waterway, located on the landward side of the barrier islands along the South Carolina coast, are quite complex because of reversing tidal flows, interconnected tidal creeks, multiple connections between barrier islands and the Atlantic Ocean, wetting and drying of extensive tidal marshes, and semidiurnal tides with a 5to 7-foot (ft) vertical range. Often, flows in these systems are characterized by large, bidirectional tidal excursions during the flood and ebb tides and by small residual (net) flows over the tidal cycle. Dye fluorometry is an established method for tracing the movement of water in many hydrologic settings. When used as a tracer, the concentration of a dye is directly proportional to its fluorescence. Background fluorescence can interfere or enhance the fluorescence of the dye, thereby causing overestimation of the movement and dispersion of the dye (Hartel and others, 2007). Elevated background fluorescence can be caused by optical brighteners commonly found in the effluent of wastewater treatment plants and septic tanks. Optical brighteners have the ability to fluoresce and interfere with the measurement of rhodamine dye used as a hydrologic tracer. Other sources of background fluorescence include naturally occurring humic substances that produce the “blackwater” of coastal waters, synthetic organic compounds that can reach the water during rainfall runoff, and various by products from pulp and paper production (Hartel and others, 2007). The U.S. Geological Survey (USGS), in cooperation with the South Carolina Department of Health and Environmental Control, initiated a data-collection effort in 2011 to measure the tidal flow dynamics and background fluorescence in the 2 Tidal Flow Dynamics and Background Fluorescence of the Atlantic Intracoastal Waterway