Ecotoxicological studies have provided extensive insights into the lethal and sublethal effects of environmental contaminants. These insights are critical for environmental regulatory frameworks, which rely on knowledge of toxicity for developing policies to manage contaminants. While varied approaches have been applied to ecotoxicological questions, perspectives related to the evolutionary history of focal species or populations have received little consideration. Here, we evaluate chloride toxicity from the perspectives of both macroevolution and contemporary evolution. First, by mapping chloride toxicity values derived from the literature onto a phylogeny of macroinvertebrates, fish, and amphibians, we tested whether macroevolutionary relationships across species and taxa are predictive of chloride tolerance. Next, we conducted chloride exposure tests for two amphibian species to assess whether potential contemporary evolutionary change associated with environmental chloride contamination influences chloride tolerance across local populations. We show that explicitly evaluating both macroevolution and contemporary evolution can provide important and even qualitatively different insights from those obtained via traditional ecotoxicological studies. While macroevolutionary perspectives can help forecast toxicological end points for species with untested sensitivities, contemporary evolutionary perspectives demonstrate the need to consider the environmental context of exposed populations when measuring toxicity. Accounting for divergence among populations of interest can provide more accurate and relevant information related to the sensitivity of populations that may be evolving in response to selection from contaminant exposure. Our data show that approaches accounting for and specifically examining variation among natural populations should become standard practice in ecotoxicology.

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. Environ Toxicol Chem 2020;39:1071–1085. © 2020 SETAC

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Fugitive dust from unpaved roads creates human health hazards, degrades road surfaces, and increases the cost of road maintenance. As a result, many different chemical treatments are applied to unpaved roads in an attempt to control dust and stabilize the wearing course. However, investigations of the effectiveness of these treatments have often been poorly planned or executed. The objective of this study was to use a combination of real-time dust monitoring and objective road condition evaluations to assess the success of two chemical treatments for a period of 19 months post-application, to provide quantitative information in support of road management decisions. Dust production from road sections treated with calcium chloride-based durablend-C™ or the synthetic fluid EnviroKleen® was monitored on five dates using a vehicle-mounted particulate matter meter. Both products reduced dust by up to 99% relative to an untreated control section during the monitoring period, and quantitative data from the meter were consistent with qualitative observations of dust conditions. Linear models of dust production indicated that road treatment and humidity explained 69% of the variation in dust over time. Road sections treated with either product developed less rutting and fewer potholes than the untreated control. Overall, the combination of real-time dust monitoring and surface condition evaluation was an effective approach for generating quantitative data on endpoints of interest to road managers.

Controlling fugitive dust while protecting natural resources is a challenge faced by all managers of unpaved roads. Unfortunately, road managers choosing between dust control products often have little objective environmental information to aid their decisions. To address this information gap, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collaborated on a field test of three dust control products with the objectives of (a) evaluating product performance under real-world conditions, (b) verifying the environmental safety of products identified as practically nontoxic in laboratory tests, and (c) testing the feasibility of several environmental monitoring techniques for use in dust control tests. In cooperation with refuge staff and product vendors, three products (one magnesium chloride plus binder, one cellulose, and one synthetic fluid plus binder) were applied in July 2012 to replicated road sections at the Hagerman National Wildlife Refuge in Texas. These sections were monitored periodically for 12 months after application. Product performance was assessed by mobile-mounted particulate-matter meters measuring production of fugitive dust and by observations of road conditions. Environmental safety was evaluated through on-site biological observations and leaching tests with samples of treated aggregate. All products reduced dust and improved surface condition during those 12 months. Planned environmental measurements were not always compatible with day-to-day refuge management actions; this incompatibility highlighted the need for flexible biological monitoring plans. As one of the first field tests of dust suppressants that explicitly incorporated biological endpoints, this effort provides valuable information for improving field tests and for developing laboratory or semifield alternatives.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:°C = (°F -32) / 1.8. DatumVertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Element R Standard identity and reference Hydrogen Hydrogen-2/hydrogen-1 (δ 2 H) Vienna Standard Mean Ocean Water (Fritz and Fontes, 1980) Oxygen Oxygen-18/oxygen-16 (δ 18O ) Vienna Standard Mean Ocean Water Stable isotope ratios of oxygen ( 18 O/ 16 O) and hydrogen ( 2 H [deuterium]/ 1 H) are shown in delta (δ) notation as δ 18 O and δ 2 H, in per mil (parts per thousand). viii ix Abbreviations a.i. active ingredient a.e. acid equivalent AMPA aminomethylphosphonic acid δ 2 H a measure of the ratio of stable isotopes hydrogen-2 and hydrogen-1 δ 18 O a measure of the ratio of stable isotopes oxygen-18 and oxygen-16 GBH glyphosate-based herbicide K ow octanol-water partitioning coefficient LC50 Acute toxicity testing determines what constitutes a lethal concentration of a substance for 50 percent of a given animal population LOAEC lowest-observed-adverse-effect concentration NOAEC no-observed-adverse-effect concentration

This article is part of the special series "Studies to Assess Resource Recovery and Evaluate Monitoring Methods for Restored Bottomland Hardwood Forests." The series documents recovery of floral and faunal resources in restored bottomland hardwood forests in northeast Indiana, USA, emphasizing optimization of data quality and level of effort expended in the assessment of service returns in compensation for contaminant-induced resource injury.

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