Geology topics

Brittany G. Perrotta

Publications and source records attributed to Brittany G. Perrotta.

10 recordsLinked to original sources

USGS2026

PFAS exposure suppresses leaf litter decomposition in a stream ecosystem

Decomposition of organic matter is critical to the biogeochemical cycling of carbon and nutrients in all ecosystems. In streams, decomposition can be influenced by anthropogenic impacts, including contaminants. Per- and polyfluoroalkyl substances (PFAS) are resistant to degradation and widespread in freshwater ecosystems, yet little is known about their influence on organic matter processing in streams. We paired an observational field study of a PFAS-impacted stream via food processing wastewater with a 28-day laboratory experiment to investigate PFAS effects on leaf litter processing using multiple lines of evidence. Leaf litter decomposition rates and microbial respiration were significantly lower downstream of the PFAS point-source compared to the paired upstream site. We hypothesized that PFAS suppressed microbial activity thereby resulting in slower decomposition rates. To investigate further and better isolate PFAS, we dosed aquatic mesocosms containing leaf packs with differing concentrations of perfluorooctane sulfonate (PFOS). Over the 28-day incubation, decomposition rates did not differ, but we observed lower respiration rates on day 28 and higher dissolved organic carbon (DOC) in PFOS-dosed mesocosms, suggesting that PFAS may suppress microbial activity and inhibit carbon processing. These results underscore that concerns regarding PFAS contamination extend beyond organismal toxicity to ecosystem-level effects. Further research is needed to understand the scale, implications, and mechanisms responsible for these changes.

Upper Mississippi River Basin↗

USGS2026

Cross-ecosystem transfer of microplastics via emergent aquatic insects to riparian spiders in a municipal wastewater-impacted system

Microplastics (plastic particles ≤5 mm) are a persistent and widespread pollutant in aquatic ecosystems, where they can accumulate in the larvae of aquatic insects inhabiting benthic habitats. Aquatic insects cross aquatic-terrestrial boundaries through metamorphosis, yet few studies have investigated their role in transporting microplastics to terrestrial ecosystems as emergent adults. This study sampled upstream and downstream of eight municipal wastewater treatment plants in the Grand River watershed, Ontario, Canada, in 2022 and 2023 to assess whether these facilities increase microplastics occurrence in aquatic and riparian food webs. Larval and adult caddisflies (Hydropsychidae), mayflies (Heptageniidae), midges (Chironomidae), and riparian spiders (Tetragnathidae) were collected to examine microplastics accumulation, retention through metamorphosis, and cross-ecosystem transfer into riparian spiders. Larval Heptageniidae, adult Chironomidae, and Tetragnathidae exhibited higher microplastic abundances downstream relative to upstream, with concentrations approximately 2.4-, 3.7-, and 2-fold higher, respectively, although the magnitude of differences varied across sites; no significant differences were observed for the other taxa. Organic (cellulose-based) and polyester fibres were the most common, representing ∼25-68% and ∼16-50% of particles across taxa, respectively. Relationships between total microfibre concentration and trophic position (δ15N) were generally weak and site specific, while trophic transfer factors >1 were observed between biofilm and larval taxa at most sites but were generally <1 between adult insects and spiders. Together, these findings demonstrate that emergent aquatic insects retain and transfer microplastics across aquatic-terrestrial boundaries to riparian predators but provide limited evidence for consistent trophic magnification across the food web. This research addresses a critical knowledge gap by advancing our understanding of microplastic uptake and movement through nearshore food webs via emergent aquatic insects.

Ontario↗

USGS2025

Bioaccumulation and transfer of per- and polyfluoroalkyl substances (PFAS) in a stream and riparian food web contaminated by food processing wastewater

We evaluated the bioaccumulation and transfer of per- and polyfluoroalkyl substances (PFAS) in a stream food web contaminated by a food processing facility. Abiotic (i.e., water, sediment, and foam) and biotic (i.e., algae, aquatic insect larvae and adults, fish, and riparian spiders) matrices were sampled upstream and downstream of the facility’s wastewater outfall. Compared with upstream, PFAS concentrations were 600-fold higher in downstream water (mean ∑ 40 PFAS 3.67 ng mL –1 ± 0.48 (standard error)) and reflected inputs from the outfall, with 6:2 fluorotelomer sulfonate (6:2 FTS) dominating the PFAS profile. Within the aquatic food web, perfluorooctanesulfonate (PFOS) was the most biomagnified, and 6:2 FTS was the most biodiluted. In contrast, insect-mediated transfer of PFAS to riparian spiders showed trophic enrichment of 6:2 FTS and dilution of PFOS. We observed significant positive associations between phospholipid membrane-water partition coefficient (log K MW ) and perfluoroalkyl carboxylate (PFCA) chain length on bioaccumulation across most biological matrices, demonstrating that these chemical parameters are predictive of PFAS bioaccumulation potential in the field. Our research reveals important differences in aquatic versus terrestrial exposure for certain PFAS and that biological processes (e.g., trophic interactions and metamorphosis) and chemical properties (e.g., chain length, log K MW , and concentration) control PFAS uptake, bioaccumulation, and transfer in linked freshwater and terrestrial ecosystems.

Environmental Science & Technology↗

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

Pesticide concentrations in multiple physical and biological stream matrices are impacted by a bioenergy production facility receiving pesticide coated corn seeds

Insecticide and fungicide seed coatings have become prevalent in conventional agriculture in recent decades. From 2015 to 2021, the AltEn bioenergy plant (Mead, Nebraska, USA) generated ethanol from almost 100% unused/expired treated corn seeds. This use of these seeds for ethanol production resulted in the accumulation of large amounts of contaminated wastewater and solid residue, a portion of which was applied to surrounding farmland. To better understand the potential long-term environmental effects from the processing of treated seeds at this facility, five nearby stream sites were sampled in 2022 after the closure of the plant; these included two sites directly impacted by AltEn, one upstream, and two downstream of the impacted sites. Water and sediment were collected in March through July, and algae and fish samples were collected in July for chemical analysis. Overall, 60 pesticide compounds (parents and transformation products) were detected in one or more matrices, including 23 fungicides, 20 insecticides, 16 herbicides, and 1 bacterial growth inhibitor. Pesticide results (maximum detection frequency, maximum concentration) varied substantially by environmental compartment: water (100% multiple pesticides; 4,600 ng L −1 thiamethoxam transformation product (NOA-407475)), algae (100% multiple pesticides, 190 ng g −1 atrazine), sediment (60% dithiopyr, 2.3 ng g −1 acetochlor) and fish (20% pyraclostrobin, 2.2 ng g −1 atrazine). Pesticides associated with treated corn seeds (e.g., insecticides clothianidin, thiamethoxam; fungicides fluoxastrobin, thiabendazole) were detected at significantly higher concentrations ( p < 0.05) in stream water from sites impacted by the AltEn facility compared to non-impacted sites. Study results indicate that pesticides associated with the AltEn facility continue to be a source of contaminants to aquatic systems after the plant’s closure in 2021.

Environmental Toxicology and Chemistry↗

USGS2025

Metal-rich lacustrine sediments from legacy mining perpetuate copper exposure to aquatic-riparian food webs

Historic copper mining left a legacy of metal-rich tailings resulting in ecological impacts along and within Torch Lake, an area of concern in the Keweenaw Peninsula, Michigan, USA. Given the toxicity of copper to invertebrates, this study assessed the influence of this legacy on present day nearshore aquatic and terrestrial ecosystems. We measured the metal (Co, Cu, Ni, Zn, Cd) and metalloid (As) concentrations in sediment, pore water, surface water, larval and adult insects, and two riparian spider taxa collected from Torch Lake and a nearby reference lake. Overall, elevated metal and metalloid concentrations, particularly Cu, were measured in all sediment samples and some surface and pore water samples collected from Torch Lake. For instance, Cu concentrations in the Torch Lake sediment were ∼200% higher than the reference lake and all measured concentrations exceeded predicted effects concentrations by at least ninefold. Within larval insect tissues, we observed 160% higher Cu concentrations than measured in the reference lake, and Cu was the only measured element above predicted effects concentrations in Torch Lake. Adult insects collected at both lakes had similar metal concentrations irrespective of exposure levels. Yet we found 100% higher copper concentrations in Torch Lake riparian spiders, demonstrating elevated exposure risk to insectivores across the aquatic-terrestrial boundary. Our results highlight that other metals in the mixture may not be as concerning to adjacent riparian ecosystems, but copper remains a contaminant of concern in Torch Lake 60 years after mining ceased.

Michigan↗

USGS2025

Effects of chronic metal exposure and metamorphosis on the microbiomes of larval and adult insects and riparian spiders through the aquatic-riparian food web

The macroinvertebrate microbiome controls various aspects of the host's physiology, from regulation of environmental contaminants to reproductive output. Aquatic insects provide critical nutritional subsidies linking aquatic and riparian food webs while simultaneously serving as a contaminant pathway for riparian insectivores in polluted ecosystems. Previous studies have characterized the transport and transfer of contaminants from aquatic to riparian ecosystems through insect metamorphosis, but both contaminant exposure and metamorphosis are energetically intensive processes that may cause host microbiomes to undergo radical transformation in structure and function, potentially affecting the host's physiology. We collected arthropods from three sites within Torch Lake, a historical copper mine in the Keweenaw Peninsula, Michigan, USA, and three sites within a nearby reference lake. Our objectives were to: 1) characterize the variation in microbiome communities and predicted metagenomic functions with legacy copper mining activity across space, among host types and family-level host taxonomy, 2) characterize how insect metamorphosis alters the microbiome community, including the degree of endosymbiotic infection, and predicted metagenomic function. We field-collected organisms, extracted their DNA, and sequenced the 16S region of the rRNA gene to characterize microbiome communities, then predicted metagenomic function. Site, lake, and host taxonomy affected the host microbiome community composition. Copper exposure increased the abundance of xenobiotic and lipid metabolism pathways in the Araneidae spider microbiome. Insect metamorphosis reduced the alpha diversity, altered the community composition, and predicted metagenomic function. We observed a bioconcentration of endosymbiotic bacteria in adult insects, especially holometabolous insects. Through metamorphosis, we observed a transition in function from xenobiotic degradation pathways to carbohydrate metabolism. Overall, contaminant exposure alters the microbiome composition in aquatic insects and riparian spiders and alters the function of the microbiome across the aquatic-riparian interface. Furthermore, metamorphosis is a critical element in shaping the aquatic insect microbiome across its life history.

Michigan↗

USGS2023

Seasonal differences and grazing pressure alter the fate of gold nanoparticles in a microcosm experiment

Gold nanoparticles (AuNPs) are used as models to track and predict NP fates and effects in ecosystems. Previous work found that aquatic macrophytes and their associated biofilm primarily drove the fate of AuNPs within aquatic ecosystems and that seasonality was an important abiotic factor in the fate of AuNPs. Therefore, the present work aims to study if grazers, by feeding on these interfaces, modify the AuNP fate and if this is altered by seasonal fluctuations. Microcosms were dosed with 44.8 μg/L of AuNP weekly for 4 weeks and maintained in environmental chambers simulating Spring and Fall light and temperature conditions. We discovered that seasonal changes and the presence of grazers significantly altered the fate of Au. Higher temperatures in the warmer season increased dissolved organic carbon (DOC) content in the water column, leading to stabilization of Au in the water column. Additionally, snail grazing on biofilm growing on the Egeria densa surface led to a transfer of Au from macrophytes to the organic matter above the sediments. These results demonstrate that climate and grazers significantly impacted the fate of Au from AuNPs, highlighting the role that grazers might have in a large and biologically more complex ecosystem.

Environmental Science & Technology↗

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↗

USGS2022

PCB exposure is associated with reduction of endosymbionts in riparian spider microbiomes

Microbial communities, including endosymbionts, play diverse and critical roles in host biology and reproduction, but contaminant exposure may cause an imbalance in the microbiome composition with subsequent impacts on host health. Here, we examined whether there was a significant alteration of the microbiome community within two taxa of riparian spiders (Tetragnathidae and Araneidae) from a site with historical polychlorinated biphenyl (PCB) contamination in southern Ontario, Canada. Riparian spiders specialize in the predation of adult aquatic insects and, as such, their contaminant levels closely track those of nearby aquatic ecosystems. DNA from whole spiders from sites with either low or high PCB contamination was extracted, and spider microbiota profiled by partial 16S rRNA gene amplicon sequencing. The most prevalent shift in microbial communities we observed was a large reduction in endosymbionts in spiders at the high PCB site. The abundance of endosymbionts at the high PCB site was 63 % and 98 % lower for tetragnathids and araneids, respectively, than at the low PCB site. Overall, this has potential implications for spider reproductive success and food webs, as riparian spiders are critical gatekeepers of energy and material fluxes at the land-water interface.

Science of the Total Environment↗