Performance of commercially available soil amendments for enhanced Cu attenuation in bioretention media.

Bioretention structures such as planter boxes, swales and rain gardens are being increasingly utilized in built landscapes as a strategy to attenuate both stormwater flows and contaminant loads. Copper (Cu) roofing materials contribute significantly higher mass loads of dissolved Cu per unit area than other surfaces such as parking lots and roadways. While a recent study demonstrated that conventional bioretention media can remove greater than 90% of Cu from copper roof runoff, the median Cu concentrations at the point of discharge from bioretention structures (66 µg L-1) still did not achieve Cu concentrations in stormwater discharges sought in some jurisdictions (for example, < 14 µg L-1). Consequently, commercially available soil amendments were assessed to improve bioretention Cu removal. The ability of biochar, greensand, and zeolite to improve Cu removal was evaluated in laboratory column studies. Additionally, the performance of zeolite as an underlayer amendment was evaluated in bioretention planter boxes treating stormwater from a picnic shelter with a partitioned copper roof. Cu was measured in the planter box influent and effluent. The field setup included 2 control planter boxes containing only standard bioretention media and 2 amended with the zeolite underlayer. Samples from ten storms were collected with flow-weighted composite sampling. Total Cu in composite samples of the influent waters ranged from 445 to 1683 µg L-1 and had a median concentration of 934 µg L-1. Total Cu in the effluent from the control planter boxes ranged from 10 to 64 µg L-1, with a mean of 29 µg L-1. Total Cu in effluent from the zeolite amended planter boxes ranged from 4 to 44 µg L-1 with a mean of 18 µg L-1. Attenuation in the control planter boxes ranged from 90 to 99% with a median of 93.4% by concentration and ranged from 95 to 99% with a median of 97.5% in the zeolite amended planter boxes.

Influence of Modern Stormwater Management Practices on Transport of Road Salt to Surface Waters.

Application of road salts in regions with colder climates is leading to ground and surface water contamination. However, we know little about how modern stormwater management practices affect the movement of road salt through urban watersheds. We investigated groundwater contamination and transport of road salts at two stormwater ponds in Baltimore County, Maryland. In association with the ponds, we documented a plume of contaminated groundwater that resulted in Cl- loadings to the adjacent stream of 6574 to 40 008 kg Cl- per winter, depending on winter snowfall. We also monitored Na+ and Cl- ion concentrations and the temporal dynamics of conductivity at a range of stream sites in watersheds with and without stormwater management ponds. Streams draining watersheds with stormwater ponds had consistently higher conductivities and Cl- concentrations during base flow conditions and often exhibited greater peaks in Cl- and conductivity associated with winter storms and subsequent melting events, despite the degree of watershed development. Our results indicate that modern stormwater management practices are not protecting surface waters from road salt contamination and suggest they create contaminated plumes of groundwater that deliver Cl- and Na+ to streams throughout the year.

Bioretention storm water control measures decrease the toxicity of copper roof runoff.

The present study evaluated the ability of 2 different bioretention storm water control measures (SCMs), planter boxes and swales, to decrease the toxicity of sheet copper (Cu) roofing runoff to Daphnia magna. The present study quantified changes in storm water chemistry as it passed through the bioretention systems and utilized the biotic ligand model (BLM) to assess whether the observed D. magna toxicity could be predicted by variations found in water chemistry. Laboratory toxicity tests were performed using select storm samples with D. magna cultured under low ionic strength conditions that were appropriate for the low ionic strength of the storm water samples being tested. The SCMs decreased toxicity of Cu roof runoff in both the BLM results and the storm water bioassays. Water exiting the SCMs was substantially higher than influent runoff in pH, ions, alkalinity, and dissolved organic carbon and substantially lower in total and dissolved Cu. Daphnids experienced complete mortality in untreated runoff from the Cu roof (the SCM influent); however, for planter and swale effluents, survival averaged 86% and 95%, respectively. The present study demonstrated that conventional bioretention practices, including planter boxes and swales, are capable of decreasing the risk of adverse effects from sheet Cu roof runoff to receiving systems, even before considering dilution of effluents in those receiving systems and associated further reductions in copper bioavailability. Environ Toxicol Chem 2017;36:1680-1688. © 2016 SETAC.

Attenuation of copper in runoff from copper roofing materials by two stormwater control measures.

Concerns have been raised over diffuse and non-point sources of metals including releases from copper (Cu) roofs during storm events. A picnic shelter with a partitioned Cu roof was constructed with two types of stormwater control measures (SCMs), bioretention planter boxes and biofiltration swales, to evaluate the ability of the SCMs to attenuate Cu in stormwater runoff from the roof. Cu was measured as it entered the SCMs from the roof as influent as well as after it left the SCMs as effluent. Samples from twenty-six storms were collected with flow-weighted composite sampling. Samples from seven storms were collected with discrete sampling. Total Cu in composite samples of the influent waters ranged from 306 to 2863 µg L(-1) and had a median concentration of 1087 µg L(-1). Total Cu in the effluent from the planter boxes ranged from 28 to 141 µg L(-1), with a median of 66 µg L(-1). Total Cu in effluent from the swales ranged from 7 to 51 µg L(-1) with a median of 28 µg L(-1). Attenuation in the planter boxes ranged from 85 to 99% with a median of 94% by concentration and in the swales ranged from 93 to 99% with a median of 99%. As the roof aged, discrete storm events showed a pronounced first-flush effect of Cu in SCM influent but this was less pronounced in the planter outlets. Stormwater retention time in the media varied with antecedent conditions, stormwater intensity and volume with median values from 6.6 to 73.5 min. Based on local conditions, a previously-published Cu weathering model gave a predicted Cu runoff rate of 2.02 g m(-2) yr(-1). The measured rate based on stormwater sampling was 2.16 g m(-2) yr(-1). Overall, both SCMs were highly successful at retaining and preventing offsite transport of Cu from Cu roof runoff.

Detectable Blood Lead Level and Body Size in Early Childhood.

Rates of childhood obesity have risen at the same time rates of high blood lead levels (BLLs) have fallen. Recent studies suggest that higher BLL is inversely associated with body size in older children (ages 3-19 years). No contemporaneous studies have examined if having a detectable BLL is associated with body size in very early childhood. We examined if detectable BLL is associated with body size in early childhood. A total of 299 birth cohort participants completed a study visit at ages 2-3 years with weight and height measurements; prior to this clinic visit, a BLL was drawn as part of routine clinical care. Body mass index (BMI) percentile and Z-score were calculated; children with BMI ≥85th percentile were considered overweight/obese at age of 2 years. Detectable BLL was defined as BLL ≥1 µg/dL. A total of 131 (43.8 %) children had a detectable BLL measured at mean aged 15.4 ± 5.5 months. Mean age at body size assessment was 2.2 ± 0.3 years (53.2 % male, 68.6 % African-American). After adjusting for race, sex, and birth weight, children with a detectable BLL had a 43 % lower risk of BMI ≥85th percentile (P = 0.041) and a 0.35-unit lower BMI Z-score (P = 0.008) compared to children without a detectable BLL. Neither race nor sex modified this association (all interactions P > 0.21). Consistent with recent studies in older children, having a detectable BLL was associated with smaller body size at ages 2-3 years. Additional research on the mechanism of this association is needed but may include mechanisms of appetite suppression via lead.

Ameliorative effects of sodium chloride on acute copper toxicity among Cope's gray tree frog (Hyla chrysoscelis) and green frog (Rana clamitans) embryos.

Urban stormwater runoff is composed of a mixture of components, including polycyclic aromatic hydrocarbons, metals, deicing agents, and many others. The fate of these chemicals is often in stormwater detention ponds that are used by amphibians for breeding. Among aquatic organisms, the toxic mechanism for many metals involves interference with active Na(+) and Cl(-) uptake. Addition of cations has been shown to reduce the toxicity of metals among some aquatic organisms through competitive inhibition, but no studies have investigated the interaction between NaCl and Cu among amphibian embryos and larvae. To determine the degree to which NaCl may ameliorate the toxicity of Cu to amphibian embryos and larvae, the authors exposed Hyla chrysoscelis (Cope's gray treefrogs) and Rana (Lithobates) clamitans (green frogs) to seven levels of Cu and NaCl in fully factorial experiments. When exposure was in artificial hard water, Cu was highly toxic to both species (96-h median lethal concentration [LC50] of 44.7 µg/L and 162.6 µg/L for H. chrysoscelis and R. clamitans, respectively). However, approximately 500 mg/L of NaCl eliminated Cu toxicity over the range of Cu concentrations used in the experiments (maximum 150 µg Cu/L for H. chrysoscelis and 325 µg Cu/L for R. clamitans). The current results suggest that NaCl is likely responsible for the toxic effects of NaCl and metal mixtures that might be typical of runoff from road surfaces in northern latitudes.

A QICAR approach for quantifying binding constants for metal-ligand complexes.

Relative metal-ligand complex stability is predicted by evaluating the relationships between physicochemical properties of metal ions and their experimental biotic and abiotic binding constants, K. Linear regression analysis showed that the softness index (σ(p)) and the covalent index (χ(2)(m) r) were especially useful in model construction for rainbow trout (Oncorhynchus mykiss), fathead minnows (Pimephales promelas) and crustaceansaquatic (Daphnia magna) based on RMSE and F-ratio criterion (F(observed)/F(critical) of ≥4). The absolute value of the log of the first hydrolysis constant |logK(OH)| correlated best with logK values for barley (R(2)=0.74, p=0.02) and earthworm (R(2)=0.82, p=0.01). In contrast, the ionic index Z(2)/r explained most of the variability of logK values for the two clays kaolinite and montmorillonite, while |logK(OH)| was a better predictor of the generic NICA-Donnan parameters for HA and FA (0.67

An enriched stable isotope technique to estimate the availability of soil zinc to Lumbricus terrestris (L.) across a salinization gradient.

An enriched stable isotope approach was developed to evaluate Zn bioavailability to Lumbricus terrestris. The decrease in (68)Zn/(66) Zn in organ tissues was used to assess the relative magnitude of the bioavailable soil Zn pool. This tool was then used to specifically evaluate bioavailability as a function of soil cation distribution. Storm-water pond soils were modified using two treatment regimens whereby H(2)O-extractable Zn was varied either by different ZnCl(2) amendments or by constant ZnCl(2) amendment followed by varying the soil cation distribution through salt amendments (NaCl or CaCl(2)). Earthworms previously equilibrated in (68) Zn-spiked soil were introduced to experimental soils, and after 2 d, removed for analysis of isotopic ratios in specific tissues. Despite a wide range of H(2)O-extractable Zn values produced by the salt treatments (0.007-24.3 mg/kg), a significant relationship between Zn turnover rate in earthworm tissues and H(2)O-extractable Zn in the salt-treated soils was not observed. Rather, considering both treatment regimens, turnover rate better correlated with Zn present in broader pools, such as that extracted by 6M HNO(3). The bioavailability of trace metals to earthworms may be poorly characterized by loosely bound fractions such as the pore water. Additionally, the turnover rate of (68)Zn in anterior organ tissues may be an effective tool to evaluate the relative magnitude of the bioavailable soil Zn pool.

Effects of zinc exposure on earthworms, Lumbricus terrestris, in an artificial soil.

Earthworms have the potential to act as trophic links for pollutants that accumulate in urban soils. However, many pollutants may act as micronutrients at low concentrations and toxins at higher concentration. When pollutants are also micronutrients, bioaccumulations may initially increase trophic transfer as pollutant concentration increase, but at higher levels toxic effects may limit population size and the potential for trophic transfer. We found support for this model among earthworms exposed to a range of soil Zn levels. Worms showed increasing bioaccumulation of Zn with increasing Zn soil concentrations, but at higher Zn levels worm growth rates decreased.

Lead and zinc bioavailability to Eisenia fetida after phosphorus amendment to repository soils.

Four phosphorus forms were investigated as potential soil amendments to decrease the bioavailability of Pb and Zn in two repository soils to the earthworm, Eisenia fetida. Treatments were evaluated by examining differences in bioaccumulation factors between amended and non-amended soils. Triple super phosphate at 5000 mg P/kg decreased both Pb and Zn bioavailability in both soils. Rock phosphate at 5000 mg P/kg decreased Zn bioavailability, but not Pb bioavailability in both repository soils. Monocalcium phosphate and tricalcium phosphate at 5000 mg P/kg did not significantly decrease Pb or Zn bioavailability to earthworms in either repository soil. In order to optimize phosphorus amendments, additional phosphorus (up to 15,000 mg P/kg) and lowered pH were used in a series of tests. The combination of lowering the pH below 6.0 and increasing phosphorus concentrations caused complete mortality in all triple super phosphate amended soils and partial mortality in the highest rock phosphate amended soils. Results indicate that triple super phosphate and rock phosphate are viable soil amendments, but care should be taken when optimizing amendment quantity and pH so that adverse environmental effects are not a by-product.

Accumulation of trinitrotoluene (TNT) in aquatic organisms: part 1--Bioconcentration and distribution in channel catfish (Ictalurus punctatus).

Little is currently known regarding the toxicokinetics of TNT in fish. In the present study, the bioconcentration and distribution of trinitrotoluene (TNT) and TNT biotransformation products was investigated in juvenile channel catfish by exposing catfish to 14C-labeled TNT in water. Uptake experiments showed relatively fast rates (k(u)=10.1 ml g(-1) h(-1)) for TNT from the water; however, bioconcentration factors for TNT were low (0.79 ml g(-1)) due to rapid biotransformation and potential elimination of TNT. Accumulation of extractable radioactivity (TNT and all extractable biotransformation products) was much greater (BCF=10.5 ml g(-1)) than that for parent compound. TNT (parent compound) bioconcentrated to the greatest extent in the gills of the fish, while total radioactivity bioconcentrated to the greatest extent in the viscera. Residual portions of the fish that contained muscle and skin had lower concentrations of TNT than the whole fish, indicating that ingestion of fish fillets would result in decreased exposure to human consumers. Although the bioconcentration potential of TNT is very low, future research needs to be conducted to identify the biotransformation products that make up most of the radioactivity in exposed fish and evaluate their potential to promote toxicity.

Accumulation of trinitrotoluene (TNT) in aquatic organisms: part 2--Bioconcentration in aquatic invertebrates and potential for trophic transfer to channel catfish (Ictalurus punctatus).

The potential of TNT to accumulate in aquatic organisms was assessed by determining bioconcentration factors for TNT and TNT biotransformation products using two benthic invertebrates (Chironomus tentans and Lumbriculus variegatus), and by determining the bioaccumulation factor of TNT and TNT biotransformation products due to TNT exposure via feeding for channel catfish (Ictalurus punctatus). In all three species, TNT was rapidly biotransformed resulting in minimal accumulation. The bioconcentration factors for parent TNT ranged from 3 to 4 ml g(-1) for the invertebrates studied, while the TNT bioaccumulation factor for catfish via oral exposure of food pellets was 2.4x10(-5) g g(-1) based on the concentration of TNT in the food pellet. As indicated by this small bioaccumulation factor, TNT accumulation in channel catfish through trophic transfer would be negligible compared to aqueous exposure (previously reported BCF of 0.79 ml g(-1)). TNT extractable biotransformation products accumulated to a greater degree than parent TNT for all three species. In addition, a large fraction of the radioactivity within all three species resisted solvent extraction. The highest bioconcentration factors occurred in L. variegatus with extractable radioactivity measuring 76 ml g(-1) and total radioactivity measuring 216 ml g(-1). Because the bioaccumulation of TNT is very low compared to the bioaccumulation of its biotransformation products, further research including identifying and determining the relative toxicities of these biotransformation products is necessary to fully evaluate the environmental risk posed by exposure to TNT.

Genetic structure and mtDNA diversity of Fundulus heteroclitus populations from polycyclic aromatic hydrocarbon-contaminated sites.

Genetic structure and diversity of mummichog (Fundulus heteroclitus) populations were investigated using mitochondrial DNA (mtDNA) sequences. Forty-six haplotypes were identified among 208 mummichog from the Elizabeth and York Rivers in Virginia, USA. No evidence of decreased gene or nucleotide diversity for mummichog from polycyclic aromatic hydrocarbon (PAH)-contaminated sites was observed. However, based on mtDNA data from 17 sites, a significant correlation (Mantel analysis, p = 0.035) was noted between genetic distance (F(ST)) and PAH concentration but not between genetic distance and geographic distance. Mummichog from the most heavily PAH-contaminated site, Atlantic Wood (AW), were genetically distinct from those of other Elizabeth River sites. At AW, high frequencies of several divergent haplotypes were observed that were more closely allied to the northern mummichog than to the more abundant southern form in the Chesapeake Bay. These data suggested that a locally stable population existed at the AW site. This conclusion is consistent with the observation that mummichog from the AW site display enhanced tolerance to PAH contamination relative to mummichog from noncontaminated sites. Conclusions about gene diversity and the correlation between genetic distance with site differences in PAH concentrations were also consistent with those from tandem genetic analyses based on allozymes.

Fish (Fundulus heteroclitus) populations with different exposure histories differ in tolerance of creosote-contaminated sediments.

Prior studies suggest that field-collected fish (Fundulus heteroclitus) from a creosote-contaminated Superfund site (Atlantic Wood Industries site, Elizabeth River, VA, USA) have enhanced tolerance to local, contaminated sediments. This study was designed to test whether other populations in the Elizabeth River at less contaminated sites also show similar tolerance and whether this tolerance is heritable. To test this, F. heteroclitus populations were sampled from four sites within the Elizabeth River with varying sediment polycyclic aromatic hydrocarbon (PAH) concentrations (3.9-264 ng PAH/g dry wt 10(3)) and one reference site in a nearby, uncontaminated estuary (York River, VA, USA; 0.27 ng PAH/g dry wt x 10(3)). Embryo assays were performed to quantify population differences in teratogenic effects during contaminated sediment exposure. Atlantic Wood sediment was mixed with reference sediment to achieve a range of sediment concentrations. Minimal differences were observed in teratogenic effects among fish taken from sites within the Elizabeth River; however, embryos of fish collected from a nearby, uncontaminated York River site and exposed to contaminated sediments had a significantly higher proportion of embryos with cardiac abnormalities than those from the Elizabeth River sites. Embryos from wild-caught and laboratory-reared Elizabeth River F. heteroclitus were simultaneously exposed to contaminated sediments, and no significant tolerance differences were found between embryos from fish taken directly from the field and those reared for a generation in the lab. Differences between fish populations from the two estuaries were larger than differences within the Elizabeth River, and these differences in tolerance were heritable.