Geology topics

Christina K. Remucal

Publications and source records attributed to Christina K. Remucal.

3 recordsLinked to original sources

USGS2025

Evaluating per- and polyfluoroalkyl substance (PFAS) prevalence and potential for biological effects in Lake Superior tributaries

Several per- and polyfluoroalkyl substances (PFAS) are Great Lakes binational chemicals of mutual concern. Although known to be persistent, data gaps regarding PFAS prevalence and biological effects exist, especially within Lake Superior’s watershed. In this 2022 study of 27 United States tributaries to Lake Superior, water samples were collected during spring runoff, summer baseflow, and fall baseflow, and stream bed-sediment samples were collected during fall. PFAS were detected in 97% of water samples and 59% of sediment samples. Summed PFAS water sample concentrations (33 analytes) were generally low relative to other environmental studies (median = 6.5 ng/L), except at Newton, Miller, and Sargent Creeks (up to 391 ng/L). Maximum water concentrations were from perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonate (PFHxS); perfluorobutanoic acid (PFBA) had the greatest median concentration. PFBA and perfluorooctanoic acid (PFOA) were most frequently detected in water samples (>90%). Summed PFAS sediment sample concentrations (33 analytes) were also generally low (median = 19 ng/kg), except at Newton and Muggun Creeks (up to 797 ng/kg). In sediment, PFOS occurred most frequently and had the greatest concentrations. The most contaminated samples came from sites with documented aqueous film forming foam or wastewater contamination; summer baseflow samples exhibited elevated PFAS concentrations. Comparison of observed water concentrations to published and derived water-quality guidelines indicated PFOS and PFHxS pose the greatest potential ecological risks. Observed PFAS mixtures may affect lipid metabolism, growth, thyroid hormones, and survival of aquatic organisms. The observed concentrations and predicted biological effects are likely underestimates of the environmental impact of PFAS. Despite low anthropogenic influence in Lake Superior’s watershed, PFAS were ubiquitous and occurred at potentially harmful concentrations.

Michigan, Minnesota, Wisconsin↗

USGS2020

Potential changes to the biology and challenges to the management of invasive sea lamprey Petromyzon marinus in the Laurentian Great Lakes due to climate change

Control programs are implemented to mitigate the damage caused by invasive species worldwide. In the highly invaded Great Lakes, the climate is expected to become warmer with more extreme weather and variable precipitation, resulting in shorter iced‐over periods and variable tributary flows as well as changes to pH and river hydrology and hydrogeomorphology. We review how climate change influences physiology, behavior, and demography of a damaging invasive species, sea lamprey ( Petromyzon marinus ), in the Great Lakes, and the consequences for sea lamprey control efforts. Sea lamprey control relies on surveys to monitor abundance of larval sea lamprey in Great Lakes tributaries. The abundance of parasitic, juvenile sea lampreys in the lakes is calculated by surveying wounding rates on lake trout ( Salvelinus namaycush ), and trap surveys are used to enumerate adult spawning runs. Chemical control using lampricides (i.e., lamprey pesticides) to target larval sea lamprey and barriers to prevent adult lamprey from reaching spawning grounds are the most important tools used for sea lamprey population control. We describe how climate change could affect larval survival in rivers, growth and maturation in lakes, phenology and the spawning migration as adults return to rivers, and the overall abundance and distribution of sea lamprey in the Great Lakes. Our review suggests that Great Lakes sea lamprey may benefit from climate change with longer growing seasons, more rapid growth, and greater access to spawning habitat, but uncertainties remain about the future availability and suitability of larval habitats. Consideration of the biology of invasive species and adaptation of the timing, intensity, and frequency of control efforts is critical to the management of biological invasions in a changing world, such as sea lamprey in the Great Lakes.

Great Lakes↗

USGS2016

Direct photolysis rates and transformation pathways of the lampricides TFM and niclosamide in simulated sunlight

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) are directly added to many tributaries of the Great Lakes that harbor the invasive parasitic sea lamprey. Despite their long history of use, the fate of lampricides is not well understood. This study evaluates the rate and pathway of direct photodegradation of both lampricides under simulated sunlight. The estimated half-lives of TFM range from 16.6 ± 0.2 h (pH 9) to 32.9 ± 1.0 h (pH 6), while the half-lives of niclosamide range from 8.88 ± 0.52 days (pH 6) to 382 ± 83 days (pH 9) assuming continuous irradiation over a water depth of 55 cm. Both compounds degrade to form a series of aromatic intermediates, simple organic acids, ring cleavage products, and inorganic ions. Experimental data were used to construct a kinetic model which demonstrates that the aromatic products of TFM undergo rapid photolysis and emphasizes that niclosamide degradation is the rate-limiting step to dehalogenation and mineralization of the lampricide. This study demonstrates that TFM photodegradation is likely to occur on the time scale of lampricide applications (2–5 days), while niclosamide, the less selective lampricide, will undergo minimal direct photodegradation during its passage to the Great Lakes.

Environmental Science & Technology↗