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

Brittany G. Perrotta; Karen A. Kidd; Kate M. Campbell; Marie Noele Croteau; Tyler Kane; Amy M. Marcarelli; R. Blaine McCleskey; Gordon Paterson; Craig A. Stricker; David M. Walters

doi:10.1093/inteam/vjae023

USGS · 70264792

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

Brittany G. Perrotta·Karen A. Kidd·Kate M. Campbell·Marie Noele Croteau·Tyler Kane·Amy M. Marcarelli·R. Blaine McCleskey·Gordon Paterson·Craig A. Stricker·David M. Walters

View original source ↗Export metadata ↓

Abstract

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.

Explore related subjects

Integrated Environmental Assessment and Management Article

Source-reported bounding extent: 47.130818916798404° to 47.19487803718532° latitude; -88.46223353281127° to -88.39059185784572° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Brittany G. Perrotta, Karen A. Kidd, Kate M. Campbell, Marie Noele Croteau, Tyler Kane, Amy M. Marcarelli, R. Blaine McCleskey, Gordon Paterson, Craig A. Stricker, David M. Walters. 2025-01-06. Metal-rich lacustrine sediments from legacy mining perpetuate copper exposure to aquatic-riparian food webs. https://doi.org/10.1093/inteam%2Fvjae023

Cite the original work for its findings. Save a collection to share your selection of sources.

Discover connections

Michigan place United STates place Article subject Integrated Environmental Assessment and Management subject Keweenaw Peninsula, Torch Lake place

Connections use source metadata and explicit phrase matches, not verified experimental comparisons.

KEEP EXPLORING

Related USGS reports

USGS2026

Composite samples for perfluorooctanesulfonate in fish may change contaminant threshold decisions

The widespread occurrence and persistence of the per- and polyfluoroalkyl substances (PFAS) in the environment may pose significant health risks to humans. Fish consumption is a direct pathway for exposure, prompting extensive monitoring. In the United States and Europe, fish consumption advisories for PFAS generally focus on perfluorooctanesulfonate (PFOS), the most frequent and abundant PFAS compound reported in fish. However, PFAS analysis is costly, leading monitoring programs to frequently use composite samples (i.e., combining different fish of the same species). This financial saving comes at an analytical cost of lost information on individual variation. It is unclear how this may influence threshold-based decisions. To test this, we used a modeling approach (i.e., Monte Carlo) based on aggregated data distributions from freshwater fish species. We simulated the measurement of PFOS for individual fish compared to composite means (three, five, and 10 fish) at different levels of error structure. These values were then compared to a typical do-not-eat threshold of 200 ng•g wet mass −1 and four metrics were estimated: (i) the probability of detecting a PFOS concentration above the threshold, (ii) the maximum simulated PFOS concentration, (iii) the number of false negative samples, and (iv) the rate of false negative samples. These results show that the probability of assigning PFOS levels above or below the threshold is shifted by masking individual value contributions in a composite sample. Because true individual contaminant loads are variable, composite sampling is a more conservative metric for contaminant thresholds. The model suggested that the greater the variability, the lower the detection probability for truly contaminated samples. Our study may help to inform sampling for monitoring programs aimed at managing human exposure to PFAS.

Integrated Environmental Assessment and Management↗

USGS2025

A comparison of ground flora sampling methods to assess recovery of bottomland forest restorations

We compared ground flora sampling methods for assessing the state of multiple bottomland forest restorations 6–21 years after restoration implementation in northeast Indiana, United States. Data from standard fixed-area plots of appropriate size and complexity for forest assessments were compared with data from smaller fixed-area plots of different shapes and plotless sampling methods. The methods were compared for their ability to (1) assess species richness and abundance, (2) detect and monitor invasive and dominant species, and (3) understand community composition. We assessed the biases of the compared methods, identified the training and skills needed to conduct sampling, and examined sampling costs in relation to total monitoring costs. Results show that smaller plots are able to detect more species per unit area sampled without significant differences in floristic quality measures. Data from smaller plots were sufficient for comprehensively describing site conditions even when less of the total site area was sampled. Although multivariate analyses of data from smaller plots yielded greater within-group dissimilarity than data from larger plots, multiple response permutation procedure analyses indicated no significant differences between nonmetric multidimensional scaling solutions based on data from the different sampling methods. Regardless of the sampling methods used to collect data, use of multivariate analyses identified a gradient of time since restoration was implemented as the dominant factor relating to differences between community composition. Sampling costs spanned a range of one order of magnitude but generally represented less than 6% of total assessment costs. Results suggest that when selecting sampling methods, matching monitoring effort to specific measurable management endpoints is more important than sampling cost.

Indiana↗

USGS2025

Comparative toxicity of aircraft deicers, runway deicers, and road salt in winter airport runoff

Aircraft deicer and anti-icer formulations and airfield pavement deicer formulations are commonly used at airports that experience freezing precipitation. In addition, road salt is often applied in urban areas surrounding airports. This mixture of deicers in receiving streams can be toxic to aquatic organisms. A 17-year study of deicers and toxicity in runoff samples from sites in and near Milwaukee Mitchell International Airport included bioassay testing of Ceriodaphnia dubia , Pimephales promelas , Raphidocelis subcapitata , and Aliivibrio fischeri concurrently with quantification of freezing-point depressants that represent presence of the various deicers. Propylene glycol was monitored to represent aircraft deicers and anti-icers, acetate and formate were monitored to represent airfield pavement deicers, and chloride was monitored to represent road salt. Toxicity endpoints (e.g., lethal concentrations and inhibitive concentrations) were compiled for 19 airport deicer products and sodium chloride. Comparison of freezing-point depressant concentrations with toxicity endpoints indicated that propylene glycol, acetate, and chloride exceeded endpoint concentrations in multiple samples: more than 70% of 492 runoff samples exceeded at least one endpoint concentration with exceedances of propylene glycol and acetate-based deicer endpoints as well as road salt endpoints. Validation of these results were observed with measured toxic effects on C. dubia , P. promelas , and R. subcapitata in bioassays conducted on undiluted samples: samples with multiple deicers exceeding endpoint thresholds had greater toxicity than samples with individual deicer endpoint exceedances, and samples with no endpoint exceedances typically exhibited less toxicity than samples with only one endpoint exceedance. A comparison of additivity of toxicity quotients with bioassay results fit a log-logistic regression curve, indicating that the condition of tested organisms degraded with increasing deicer presence. These findings suggest that concurrent reduction of runoff from aircraft, airfield pavement, and road salt deicers will be needed to eliminate aquatic toxicity in adjacent watersheds.

Wisconsin↗