Geology topics

David J. Soucek

Publications and source records attributed to David J. Soucek.

13 recordsLinked to original sources

USGS2026

Using organic compounds and salt mixtures to investigate potential mechanisms of major ion toxicity to the mayfly Neocloeon triangulifer

Field assessments and laboratory studies have demonstrated that mayflies (Ephemeroptera) are relatively sensitive to increased concentrations of major geochemical ions (Na + , Ca 2+ , Mg 2+ , K + , Cl − , SO 4 2− , HCO 3 − /CO 3 2- ), but much remains to be learned about potential mechanisms of toxicity. In the present study, we sought to determine whether solution osmolarity is sufficient to predict the toxic effects of major ions to a mayfly, Neocloeon triangulifer . We further investigated whether binary mixtures of major ion salts with common cations or common anions provide evidence of concentration addition or independent action, potentially illuminating toxicity drivers for this species. Finally, we sought to determine if there are mechanisms for major ion toxicity to mayflies that are comparable to those for other species. The toxicity of single salts showed a Ca-dependent correlation with the total component concentration (the sum of individual ion concentrations, a close correlate of osmolarity), but the effect concentrations were well below those causing toxicity from mannitol (presumed to have only an osmotic effect), suggesting that a general osmotic effect is not responsible for major ion toxicity in this species. The mixture experiments consistently indicated additive toxicity and consistency with the relationship to total component concentration, which supports a single toxic mechanism and thus no evidence for ion-specific mechanisms, as reported for other species. Given the lack of evidence of ion-specific toxicity, the total component metric is likely useful for a broad range of ionic compositions.

Environmental Toxicology and Chemistry↗

USGS2026

Effects of 6PPD, 6PPD-quinone, and potential alternatives on freshwater mussels.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is an antioxidant and antiozonant widely used in tires. When 6PPD reacts with ozone, it transforms into a breakdown product called 6PPD-quinone (6PPDQ). Both compounds are currently being studied because of their high aquatic toxicity to fish, particularly coho salmon ( Oncorhynchus kisutch ). The Washington State Legislature directed Ecology to perform an Alternatives Assessment on 6PPD in motor vehicle tires. The goal is to identify and evaluate potential replacement compounds for these products. As part of this work, Ecology is studying how potential alternatives interact with species of concern and compare those effects with what is already known about 6PPD and 6PPDQ. One of those species of concern is freshwater mussels. Freshwater mussels are an imperiled group of organisms with high cultural and ecological significance. However, there are major data gaps concerning how 6PPD affects aquatic species other than salmonids. Mussels are of particular concern due to their unique parasitic life cycle where a fish host is required to fully develop into a juvenile. If their fish host is sensitive to 6PPD, mussel populations could also be at risk. This project aims to determine lethal and sublethal toxicity of 6PPD, 6PPDQ, and any potential alternatives to freshwater mussels. This objective will be accomplished by conducting acute toxicity tests with the compounds to determine median lethal concentrations (LC 50 s) of the tested compounds to freshwater mussels. Sublethal toxicity will be studied by then determining if the presence of 6PPD, 6PPDQ, and potential alternatives impacts the mussel’s ability to use a fish host for the important parasitic stage of its life cycle.

Washington↗

USGS2025

Sensitivity of mayfly Neocloeon triangulifer to a reference toxicant is significantly impacted by the age of the diatom feed species Navicula pelliculosa

The development of standardized toxicity tests is critical for assessing pollutants in aquatic ecosystems. The mayfly Neocloeon triangulifer offers advantages as a test species due to its asexual reproduction, short life cycle, and high sensitivity to pollutants. However, we identified variability in response sensitivity to pollutants, which may stem from the nutritional composition and growth stage of its primary food source, Navicula spp. diatoms. This study aimed to evaluate the repeatability and reproducibility of 96 h toxicity tests to sodium chloride with N. triangulifer fed diatoms of varying ages (target concentrations: 329, 494, 741, 1111, 1666, and 2500 mg/L). We tracked Navicula spp. growth stages under controlled conditions and characterized fatty acid and lipid contents at each stage to assess how these factors influence N. triangulifer sensitivity to sodium chloride, a common reference toxicant. Sensitivity increased significantly as the diatom feed aged, highlighting the need for standardized culturing methods to improve test reliability. This study is the first to simultaneously characterize the growth stages and fatty acid profiles of Navicula spp. diatoms as feed species for N. triangulifer . This work contributes valuable insights to the optimization of standardized toxicity testing with this sensitive aquatic insect.

Ecotoxicology and Public Health↗

USGS2025

Targeted quantitation of 6ppd-quinone in fish tissue samples with liquid chromatography-tandem mass spectrometry

The tire additive transformation product N -(1,3-dimethylbutyl)- N’ -phenyl- p -phenylenediamine-quinone (6PPD-quinone) has recently garnered global attention due to its acute toxicity to some salmonids, such as coho salmon ( Oncorhynchus kisutch ), and its ubiquitous presence in urban stormwater systems. In the present study, we developed and compared the extraction efficiency of two sample preparation methodologies for quantification of 6PPD-quinone among two fish tissue sample types that included fillet of smallmouth bass ( Micropterus dolomieu ) and whole-body samples of O. kisutch fry subjected to in vivo exposure tests with 6PPD-quinone. The two sample preparation methods tested included an accelerated solvent extraction (ASE) approach and a sonication extraction approach. Both sample preparation methods included identical purification steps for the crude sample extracts with enhanced matrix removal cartridges. The purified sample extracts were subjected to targeted analysis of 6PPD-quinone using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results showed that extractions made with the reported ASE method demonstrated significantly higher absolute recovery (80–96%) of the extracted internal standard, [ 13 C 6 ]-6PPD-quinone, than sonication-based extractions (74–80%) in both fish tissue sample types. The proposed ASE method shows acceptable limits of quantification (0.37–0.67 ng g −1 ), linearity (R 2 > 0.996), and repeatability (RSD ≤ 9%). This work advances research capabilities for investigations on the toxicokinetic processes of 6PPD-quinone in biological samples.

Environmental Toxicology and Chemistry↗

USGS2025

Concentration dependency of PFOS bioaccumulation by freshwater benthic algae

Although perfluorooctanesulfonic acid (PFOS) has been voluntarily phased out, it remains the most abundant and frequently detected PFAS compound in biota worldwide. A deeper understanding of how PFOS enters the aquatic food web at the energetic base is needed to better characterize and predict the general patterns of PFAS trophic transfer. Research on bioaccumulation by primary producers remains limited. Because diatoms (Bacillariophyta) are often dominant constituents of aquatic biofilms, we exposed freshwater benthic diatoms ( Mayamaea atomus ) to a range of PFOS concentrations (0.01–100 μg/L) for 7 days in a controlled laboratory experiment to investigate PFAS bioaccumulation patterns. We quantified PFOS in water and algal matrices using liquid chromatography-tandem mass spectrometry and calculated bioconcentration factors (BCFs). Log PFOS concentrations in diatoms increased linearly with log 10 exposure concentration, corresponding to a sublinear relationship in arithmetic space. Consequently, BCF values decreased, from 4,831 to 174 L/kg, with increasing PFOS exposure, indicating concentration-dependent bioaccumulation consistent with higher-order organisms (e.g., Crustacea, Mollusca, Chordata). This pattern complicates the use of BCF for predictive purposes and may lead to mis-estimations of risk. Even as PFOS declines in the environment, algae will likely continue to accumulate and transfer PFOS and other PFAS to higher trophic levels.

ACS ES&T Water↗

USGS2025

Acute Toxicity of 4-hydroxydiphenylamine (4-HDPA) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPDQ), transformation products of 6PPD, to early instars of the mayfly, Neocloeon triangulifer

Our analysis of water samples collected during a rain event from two urban rivers in the Greater Toronto area, Ontario, Canada, indicated that selected transformation products (TPs) of the tire antioxidant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), including 6PPD-quinone (6PPDQ) and 4-hydroxydiphenylamine (4-HDPA), were present at concentrations >1 µg/L. In acute (96-hr) toxicity tests with aquatic larvae of the mayfly Neocloeon triangulifer , 6PPDQ did not cause mortalities at the highest test concentration, which was just below the limit of solubility. In toxicity tests with 4-HDPA, a calculated 96-hr median lethal concentration of 339 µg/L is above environmentally relevant concentrations. However, in toxicity tests with 6PPD, there was evidence that the degradation of this tire wear compound produced unknown TPs that caused mortalities in exposed mayfly larvae. Additional work could identify other TPs of 6PPD that could be a hazard to aquatic invertebrates exposed to tire wear compounds transported into surface waters from transportation corridors.

Ontario↗

USGS2023

Trace elements and consequent ecological risks in mining- influenced streams of Appalachia

Appalachian coal surface mines fracture geologic materials, causing release of both major ions and trace elements to water via accelerated weathering. When elevated above natural background, trace elements in streams may produce adverse effects to biota via direct exposure from water and sediment and via dietary exposure in food sources. Other studies have found elevated water concentrations of multiple trace elements in Appalachia's mining-influenced streams. Excepting Se, trace-element concentrations in abiotic and biotic media of Appalachian mining-influenced streams are less well-known. We analyzed environmental media of headwater streams receiving alkaline waters from Appalachian coal mines for eight trace elements (Al, As, Cd, Cu, Ni, Sr, V, and Zn) and assessed potential consequent ecological risks. Streamwater, particulate media (sediment, biofilm, leaf detritus) and benthic macroinvertebrates (primary consumers, secondary consumers, crayfish) were sampled from six mining-influenced and three reference streams during low-flow conditions in two seasons. Dissolved Cu, Ni, and Sr were higher in mining-influenced streams than in reference streams; whereas Ni, Sr, and Zn in fine sediments and Ni in macroinvertebrates were also elevated relative to reference-stream levels in samples from mining-influenced streams. Seasonal ratios of mining-influenced stream concentrations to maximum concentrations in reference streams also demonstrated mining-influenced increases for several elements in multiple media. In most media, concentrations of several elements including Ni were correlated positively. All water-column dissolved concentrations were below protective levels, but fine-sediment concentrations of Ni approached or exceeded threshold-effect concentrations in several streams. Further study is warranted for several elements (Cd, Ni, and Zn in biofilms, and V in macroinvertebrates), which approached or exceeded previously established dietary-risk levels.

Virginia, West Virginia↗

USGS2023

Perfluorooctanesulfonate adversely affects a mayfly (Neocloeon triangulifer) at environmentally realistic concentrations

Of the emerging contaminant types thought to threaten freshwater biota, per- and polyfluoroalkyl substances appear to be particularly widespread, and limited studies conducted with these compounds thus far indicate insects may be particularly sensitive to them. This study investigated the short- and long-term effects of two commonly detected compounds on the laboratory-reared mayfly Neocloeon triangulifer in water only exposures. In acute tests, the mayfly was approximately 85-fold more sensitive to perfluorooctanesulfonate (PFOS) and 7-fold more sensitive to perfluorooctanoic acid (PFOA) than the next most sensitive species reported in the literature. In 14 day and full-life chronic PFOS toxicity tests, the lowest 10% effect concentration was 0.272 μg of PFOS/L, which is lower than any previous reports to the best of our knowledge, but consistent in demonstrating the sensitivity of insects to this compound. Conversely, N. triangulifer was not particularly chronically sensitive to PFOA. This study demonstrates the risks of environmentally relevant concentrations of PFOS to a freshwater insect and suggests that investigation of the toxicity of more compounds with different carbon-chain lengths and functional groups to freshwater insects is needed.

Environmental Science & Technology Letters↗

USGS2023

Guide for benthic invertebrate studies in support of Natural Resource Damage Assessment and Restoration

This guide is intended to assist with characterizing injury to freshwater benthic macroinvertebrates (BMIs) in Natural Resource Damage Assessment and Restoration (NRDAR) cases. The contents are narrowly focused on insects, crustaceans, snails, and other invertebrate fauna that are typically considered part of BMI communities and are not intended to address studies of injury to larger benthic taxa such as freshwater mussels, crayfish, or benthic fishes or amphibians. Although some percentage of the community functions as predators, BMIs are predominantly primary consumers (for example, scrapers, shredders, and filterer/gatherer feeding groups) that play an essential role in converting carbon and nitrogen from plant tissues into animal biomass for higher-order consumers, especially in flowing waters. Aquatic contaminants can disrupt the quantity and quality of energy transferred (ecosystem function) by reducing invertebrate biomass and diversity. Additionally, the accumulation of toxic residues in invertebrate tissues may be a source of exposure leading to adverse effects in higher trophic levels. The goal of NRDAR BMI assessments is to establish direct linkages of contaminant exposure to injuries reflected by changes in community structure (for example, reduced density and taxa richness) or by effects at the individual population level (for example, survival, growth, and reproduction). BMIs are infrequently the U.S. Department of Interior (DOI)-managed resource in a NRDAR case, with managed resources more frequently including migratory birds, fish, or other insectivorous vertebrates. Therefore, it is critical to have clearly defined objectives for evaluating BMIs and an understanding of how invertebrate data relate to the quantification of injuries to the DOI-managed resource. This guide is intended to assist decisions on whether or not to proceed with BMI studies, use of existing information and data for screening purposes, and what types of studies can support a BMI-injury determination. This document is intended to provide general considerations and best practices for assessing BMIs. Relevant guidance and references are listed throughout the report as sources for specific methods and analysis.

Open-File Report↗

USGS2022

Influence of test method variables on sensitivity of Neocloeon triangulifer to a reference toxicant in short-term, effluent style evaluations

Recent literature has demonstrated the sensitivity of mayflies to environmental contaminants. However, to date, there are no methods approved by the US Environmental Protection Agency for using sensitive insects like mayflies in whole-effluent toxicity or receiving water toxicity tests. The parthenogenetic mayfly Neocloeon triangulifer has been shown to be amenable to continuous culture in the laboratory, and methods have been described for its use in both acute and chronic toxicity studies. The goal of the present study was to investigate aspects of N. triangulifer testing and culturing methods that might require adjustment so that they are applicable for testing effluents and receiving waters in a short-term exposure. To this end, the influence of organism age, test duration, and test temperature on sensitivity to NaCl as a reference toxicant were tested (concentrations ranging from 182 to 2489 mg/L). Further studies were conducted to assess the utility of commercially available diets and the influence of nutrient amendment of water on organism growth and sensitivity. Seven-day NaCl tests started with less than 24-h-old larvae were similar in sensitivity to 14-day and full life chronic tests, and were much more sensitive than those started with 7-day-old organisms. Reducing test temperature from 25 °C to 22 °C had a minor influence on culture timing, and little impact on sensitivity to NaCl. In other experiments, reconstituted test water supplemented with nutrients to potentially improve in-test food quality had minimal effect on growth at 7 days and did not significantly alter acute sensitivity to NaCl relative to unamended reconstituted water. A suitable commercially available, ready-to-feed diet substitute for cultured diatoms was not found. Testing N. triangulifer in effluents or receiving waters with the methods recommended will complement similar methods for Ceriodaphnia dubia .

Environmental Toxicology and Chemistry↗

USGS2021

Modeling the bioavailability of nickel and zinc to Ceriodaphnia dubia and Neocloeon triangulifer in toxicity tests with Natural Waters

We studied biotic ligand model (BLM) predictions of toxicity of nickel (Ni) and zinc (Zn) in natural waters from Illinois and Minnesota USA which had combinations of pH, hardness, and dissolved organic carbon (DOC) more extreme than 99.7% of waters in a nationwide database. We conducted 7-d chronic tests with Ceriodaphnia dubia, and 96-hr acute test and 14-d chronic tests with Neocloeon triangulifer, and estimated LC50s and EC20s for both species. Toxicity of Ni and Zn to both species differed among test waters by factors from 8 (Zn tests with C. dubia ) to 35 (Zn tests with N. triangulifer ). For both species and metals, tests with Minnesota waters (low pH and hardness, high DOC) showed lower toxicity than Illinois waters (high pH, high hardness, low DOC). Recalibration of the Ni BLM to be more responsive to pH-related changes improved predictions of Ni toxicity, especially for C. dubia . We compared several input data scenarios for the Zn BLM, which generally had minor effects on Model Performance Scores (MPS). A scenario that included inputs of modeled dissolved inorganic carbon and measured Al and Fe(III) produced highest MPS values for tests with both C. dubia and N. triangulifer . Overall, the BLM framework successfully modeled variation in toxicity for both Zn and Ni across wide ranges of water chemistry in tests with both standard and novel test organisms.

Illinois, Minnesota↗

USGS2020

Acute and chronic toxicity of sodium nitrate and sodium sulfate to several freshwater organisms in water-only exposures

Elevated nitrate (NO3) and sulfate (SO4) in surface water are of global concern, and studies are needed to generate toxicity data to develop environmental guideline values for NO3 and SO4. The present study was designed to fill existing gaps in toxicity databases by determining the acute and/or chronic toxicity of NO3 (tested as NaNO3) to a unionid mussel (Lampsilis siliquoidea), a midge (Chironomus dilutus), a fish (rainbow trout, Oncorhynchus mykiss), and 2 amphibians (Hyla versicolor and Lithobates sylvaticus), and to determine the acute and/or chronic toxicity of SO4 (tested as Na2SO4) to 2 unionid mussels (L. siliquoidea and Villosa iris), an amphipod (Hyalella azteca), and 2 fish species (fathead minnow, Pimephales promelas and O. mykiss). Among the different test species, acute NO3 median effect concentrations (EC50s) ranged from 189 to >883 mg NO3‐N/L, and chronic NO3 20% effect concentrations (EC20s) based on the most sensitive endpoint ranged from 9.6 to 47 mg NO3‐N/L. The midge was the most sensitive species, and the trout was the least sensitive species in both acute and chronic NO3 exposures. Acute SO4 EC50s for the 2 mussel species (2071 and 2064 mg SO4/L) were similar to the EC50 for the amphipod (2689 mg SO4/L), whereas chronic EC20s for the 2 mussels (438 and 384 mg SO4/L) were >2‐fold lower than the EC20 of the amphipod (1111 mg SO4/L), indicating the high sensitivity of mussels in chronic SO4 exposures. However, the fathead minnow, with an EC20 of 374 mg SO4/L, was the most sensitive species in chronic SO4 exposures whereas the rainbow trout was the least sensitive species (EC20 > 3240 mg SO4/L). The high sensitivity of fathead minnow was consistent with the finding in a previous chronic Na2SO4 study. However, the EC20 values from the present study conducted in test water containing a higher potassium concentration (3 mg K/L) were >2‐fold greater than those in the previous study at a lower potassium concentration (1 mg K/L), which confirmed the influence of potassium on chronic Na2SO4 toxicity to the minnow.

Environmental Toxicology and Chemistry↗

USGS2020

Acute and chronic toxicity of nickel and zinc to a laboratory cultured mayfly (Neocloeon triangulifer) in aqueous but fed exposures

Aquatic insects are poorly represented in water quality criteria, and previous studies have suggested a lack of sensitivity in acute toxicity tests despite observational studies demonstrating the contrary. Our objectives were to determine the toxicity of nickel (Ni) and zinc (Zn) to the mayfly Neocloeon triangulifer in fed acute (96-h) and chronic exposures to estimate aqueous effect concentrations while acknowledging the importance of dietary exposure for these insects. For the chronic tests, we conducted preliminary full–life cycle (~25–30 d) and subchronic (14 d) exposures to compare the relative sensitivity of the 2 test durations under similar conditions (i.e., feeding rates). Observing similar sensitivity, we settled on 14 d as the definitive test duration. Furthermore, we conducted experiments to determine how much food could be added to a given volume of water while minimally impacting dissolved metal recovery; a ratio of food dry mass to water volume (<0.005) achieved this. In the 14-d tests, we obtained a median lethal concentration and most sensitive chronic endpoint of 147 and 23 µg/L dissolved Ni (acute to chronic ratio [ACR] = 6.4), respectively, and 81 (mean value) and 10 µg/L dissolved Zn (ACR = 8.1), respectively. The acute values are orders of magnitude lower than previously published values for mayflies, probably most importantly due to the presence of dietary exposure but also potentially with some influence of organism age and test temperature.

Environmental Toxicology and Chemistry↗