Avoidance of copper (Cu) by rainbow trout (Oncorhynchus mykiss) was evaluated using a Y-maze exposure system, with data collected over a 1-h exposure period using a digital camcorder. In exposures to five measured concentrations of dissolved copper (<0.3, 1.2, 9.8, 48.3, and 98.6 µg Cu/L), plus control, significant avoidance behavior (p < 0.05) relative to the control was observed at ≥9.8 µg Cu/L, but not at 1.2 µg Cu/L. The chronic value (i.e., geometric mean of these concentrations) was 3.43 µg Cu/L. Estimates of EC50 values for avoidance of Cu ranged from 4.81 to 9.15 µg Cu/L over four 15-min time intervals of exposure to the metal. Based on water quality characterization of the control/diluent water, the U.S. Environmental Protection Agency (USEPA) water hardness- and biotic ligand model (BLM)-based chronic criteria for dissolved Cu were 8.03 and 2.26 µg Cu/L, respectively. This study suggested that enforcement of the BLM-based criterion would provide a higher level of protection of trout for this sensitive response than the hardness-based criterion.

Two reviews focused on metals, two on organics, and one on potential implications of climate change on new water legislation in the United States.Additionally, seven articles that were published during the year, including the retrospective by Schultz and Aptula and focused reviews from May, September and October, were selected by the editors to highlight the breadth of the papers the Bulletin receives and publishes.The remaining three articles were by Schmitt and McKee (2016

Juvenile marine polychaetes, Neanthes arenaceodentata, were exposed for 28 days to copper (Cu)-spiked sediment at six concentrations ranging from 48.3 to 2380 mg Cu/kg dry sediment, plus control. Survival was reduced (p ≤ 0.05) at concentrations ≥1190 mg Cu/kg. Growth was inhibited at Cu concentrations ≥506 mg Cu/kg. Dose–response relationships yielded LC10 and LC50 estimates of 514 and 1230 mg Cu/kg, respectively. The growth effect EC50 estimate was 409 mg Cu/kg. Ranges for the no observable effect concentration and lowest observable effect concentration were 506–1190 mg Cu/kg for survival, and 230–506 mg Cu/kg for growth. Pore water concentrations of Cu were 38.7–65.8 µg Cu/L in exposures where toxic effects were observed, compared to a range of 15.1–22.4 µg Cu/L in exposures where significant effects were not evident. The results of the study were compared with empirical and mechanistic sediment quality guidelines for the protection of benthic organisms.

Leptocheirus plumulosus was exposed for 28 days to Cu-spiked sediment at mean concentrations ranging from 44.4 to 605 mg Cu/kg dry sediment in a sediment/water test system designed to simulate natural conditions. The NOEC (no observed effect concentration)—LOEC (lowest observed effect concentration) range for the most sensitive endpoint of growth was 199–414 mg Cu/kg sediment. An IC50 for reproduction was estimated at 187 mg Cu/kg sediment. Mean Cu concentrations in pore water (PW) where significant effects were observed were 25.8 and 59.0 µg/L, while their respective concentrations in overlying water (OW) were 22.1 and 28.0 µg Cu/L. Copper concentrations were ≤19.1 and <16.6 µg/L in PW and OW, respectively, at lower exposures where effects were not evident. Concentrations of Cu in marine sediment lower than sediment quality guidelines based on geochemical factors of acid volatile sulfide, organic carbon content (f OC), and sediment grain size (i.e., silt + clay) would appear not to result in adverse effects toward L. plumulosus.

Sediment collected from two freshwater lakes, West Bearskin Lake (Cook, MN, USA) and Bond Lake (Douglas, WI, USA), was characterized for grain size, total organic carbon, (TOC), acid-volatile sulfides (AVS), simultaneously extracted metals (SEM), and iron (Fe). Both sediments had low levels of TOC (<1.0 percent) and AVS (<1.1 mu mol/g). West Bearskin Lake sediment contained more small (silt and clay) particles than Bond Lake, which was 95% sand. West Bearskin Lake also had higher SEM (Sigma SEM = 0.815 vs 0.074 mu mol/g) and had an Fe content that was approximately 30-fold greater than that of Bond Lake. These sediments were amended with AgNO3 in a series of concentrations, some of which were intended to exceed the total silver (Ag)-binding capacity of the sediments, allowing for the appearance of dissolved Ag in pore water (PW). Sediment toxicity tests were then designed such that the AgNO3 amendment levels would result in PW concentrations that bracketed the 10-d concentration causing 50% lethality (LC50) for dissolved Ag of 0.057 mg/L, as determined in a toxicity test in water alone (i.e., without sediment present). The 10-d LC50 values for Chironomus tentans, based upon nominal additions of Ag to the sediments, were 2.75 and 1.17 g Ag per kilogram dry sediment for West Bearskin and Bond Lake sediments, respectively. An LC50 value based upon dissolved Ag in the PW was determined only for Bond Lake sediment and was approximately 275 times greater than the water-only LC50 value. This indicated that a high proportion of the dissolved fraction was not readily bioavailable to cause lethality. A reduction in PW pH and the displacement of other metals from sediment into PW with Ag additions to the sediment likely contributed to the observed mortalities and weight losses, particularly at the higher exposure levels. The concentrations of Ag in these sediments that resulted in biological effects are considerably higher than levels reported in the environment.

Understanding relationships between cationic metals such as cadmium, copper, nickel, lead and zinc, and amorphous iron sulfides, measured as acid volatile sulfide (AVS), is key to predicting metal bioavailability and toxicity insediments. The objective of the present study was to assess seasonal and spatial variations of AVS in freshwater sediments contaminated with zinc. Sediments were sampled from three streams with varying levels of zinc contamination at two different times, March and June of 1995, representing cold- and warm-weather situations. Interstitial (pore) water concentrations of zinc, and solid phase concentrations of AVS and zinc were measured in surficial and deep sediment horizons. Toxicity tests (10-d) with the amphipodHyalella azteca were conducted using intact cores. Sediment zinc concentrations from six sites within the primary test stream differed by about five-fold, and also varied seasonally. Acid volatile sulfide concentrations were generally lower than those of zinc, and pore water zinc concentrations typically were elevated. There was a positive correlation between solid-phase AVS and zinc concentrations, suggesting that the system was dominated by zinc, as opposed to iron sulfides. In contrast to expectations arising from some studies of seasonal variations of AVS in iron-dominated systems, AVS concentrations were smaller in June than in March. However, this was likely due to a major storm event and associated sediment scouring before the June sampling, rather than to seasonal processes related to variations in temperature and dissolved oxygen. Based upon an indirect analysis of depth variations in AVS, there was some indication that zinc sulfide might be less prone to oxidation than iron sulfide. There was a strong correlation between toxicity of the sediment samples toH. azteca and interstitial water concentrations of zinc; however, the possible contribution of other contaminants to sediment toxicity cannot be dismissed.

A laboratory study was conducted with Chironomus tentans to assess the significance of growth retardation of third-to fourth-instar larvae over a 10-d test period on long-term survival, adult emergence, and ovipositing success. Data were intended to provide interpretive guidance for the commonly used growth endpoint in 10-d sediment bioassays with C. tentans. Larval growth was controlled by using six feeding levels ranging from 0.2 to 5.9 mg dry weight Tetrafin® fish food per day. Mean 10-d survival was ≥88% at all feeding levels, but larval growth decreased significantly (p<0.05) with each decrease in feeding level. Cumulative successful emergence of adult C. tentans decreased significantly with decreasing larval growth. Mean times to emergence always increased with decreasing growth rates and effects were generally more pronounced for females than males. At the lowest 10-d mean growth where successful emergence occurred (0.27 mg), the times to emergence doubled relative to the times observed at the highest 10-d mean growth (1.03 mg). Ten-day larval growth retardation was strongly correlated with reduction in adult emergence success (r2 = 0.96). Growth retardations ≥64% resulted in 86–100% reductions in adult emergence. Growth retardation in the range of 35 to 50% equated with comparable percent reductions in adult emergence success. Although fewer females successfully emerged at 10-d growths of 0.37 and 0.74 mg relative to the highest 10-d growth (1.03 mg), ovipositing success of these females did not appear to be adversely affected by either their slower growth rates or their lower mean dry weights (0.62 and 0.99 mg, respectively). Growth of second generation larvae did not appear to be affected by maternal growth rate, but rather appeared to be solely correlated with their own feeding level.

The concept that phototoxic chemicals can be identified in chemical risk assessments by computing the energy difference between highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gap) was evaluated using two new sets of phototoxicity data from the recent literature. The original model, developed from data with unsubstituted PAH toxicity to Daphnia magna, showed that phototoxicity was observed when the HOMO-LUMO gap varied between 6.7 and 7.5 eV. All substituted alpha-terthienyls that were phototoxic to mosquito larvae and to brine shrimp had HOMO-LUMO gap energies within the 7.1 +/- 0.4 eV ''phototoxicity window''. The alpha-terthienyls within this range that did not exhibit phototoxicity contained carboxyl or other polar substituents,which likely prevented bioaccumulation in the organisms. Polyamino and polynitro derivatives of toluene in munitions wastes were reported to be phototoxic to sea urchins even though the HOMO-LUMO gap energies exceeded 8.0 eV. Because the same toluenes were not phototoxic to D. magna nor to Escherichia coli, we suggest that the developmental effects observed in the sea urchins were caused by electrophilic species from metabolic activation rather than the production of oxygen radicals from photo induced excited states of the molecules.

Sediment collected from 11 sites within the Fox and East Rivers of Brown County, Wisconsin, and two near-shore sites in Green Bay (Lake Michigan) were analyzed for organic carbon content and various pesticides, polychlorinated biphenyls (PCBs), chlorodibenzodioxins, chlorodibenzofurans, polycyclic aromatic hydrocarbons (PAHs), sulfur and heavy metals. Representative chemicals from the organic and inorganic groups were examined for their concentrations at the various sites relative to organic carbon content. Correlations between organic carbon and contaminant concentrations resulted in simple linear regression models with high degrees of predictive capability for most chemicals. For example, chemical concentration relationships with organic carbon (r{sup 2}) were p,p{prime}-DDE (0.85), total PCBs (0.69), 2,3,7,8-tetrachlorodibenzodioxin (0.76), 1,2,3,6,7,8-hexachlorodibenzodioxin (0.87), 2,3,7,8-tetrachlorodibenzofuran (0.71), fluoranthene (0.46), pyrene (0.51), total sulfur (0.75), cadmium (0.76), copper (0.84), lead (0.85), zinc (0.80), chromium (0.04), and nickel (0.39). All correlations were positive with the exception of nickel. This suggests that contaminants within the lower Fox River/Green Bay system are at steady-state with respect to organic carbon. Knowledge of relationships such as this within aquatic systems may be useful in planning and budgeting contaminant mass balance studies within the systems.

Abstract Direct calculation of the energy of excited states for polycyclic aromatic hydrocarbons using semi-empirical methods on a supercomputer were inadequate in explaning spectrosopic data or measured phototoxicity. The energy difference between frontier orbitals HOMO-LUMO gap of “average” excited state structures of the PAHs correlated with the measured excited state energies and their observed photoinduced toxicity. The multi-linear relationship between phototoxicity and hypothetical triplet state HOMO-LUMO gap is similar to that based on ground state structures. This molecular descriptor discriminated phototoxic PAHs into a narrow range of approximately 6.2+ mn;0.4 eV. Chemicals with a HOMO-LUMO gap in the triplet state greater than 7.1 eV were not phototoxic in simulated sunlight. Chemicals with gaps less than 5.8 eV are likely to be unstable in water and degrade too rapidly to enable determination of photoinduced potency to aquatic organisms. Several preliminary structure-phototoxicity relationshi...

Fathead minnows (Pimephales promelas) were exposed to technical grade propanil (3′,4′-dichloropropionanilide) in a flow-through diluter system to determine acute lethality. LC50 values were 11.5, 10.2, 8.6, and 3.4 mg·L−1 at 24, 48, 96, and 192 hr, respectively. Eggs, newly hatched fry, and juvenile fish of this species were similarly exposed but at lower concentrations and for a period of 58 days. The 58-day “no effect” concentration was between 0.4 and 0.6Μg·L−1, based upon the physiological parameters of length and dry weight of juvenile fish.14C-Propanil did not bioconcentrate significantly in fathead minnows (1.6× for parent propanil in whole body). Rainbow trout (Salmo gairdneri) readily metabolized propanil, forming at least ten products. One metabolite recovered from trout bile was identified as either 3′,4′-dichloro-2-hydroxypropionanilide or 3′,4′-dichloro-3-hydroxy-propionanilide. The technical grade propanil also contained 0.67 mg·g−1 of 3,3′,4,4′-tetrachloroazobenzene as a contaminant.

Uptake rates of total14C in fathead minnows (Pimephales promelas) exposed to sublethal concentrations of radiolabeled test compounds followed the order: phenol > 2,4,5-trichlorophenol >p-nitrophenol. Mean whole body14C concentration factors were 15,800, 1,850, and 180 for phenol, 2,4,5-trichlorophenol, andp-nitrophenol exposures, respectively. Only minor amounts of tissue14C was parent compound after 28 days of exposure in fish exposed to phenol andp-nitrophenol, while 78.6% of the14C was parent compound in 2,4,5-trichlorophenol exposed fish. Tissue14C in fish exposed to 2,4,5-trichlorophenol was eliminated at a faster rate than in fish exposed to phenol orp-nitrophenol. Observed mean14C depuration half-lives for lower and higher exposures combined were 387, 150, and 12 hours for phenol,p-nitrophenol, and 2,4,5-trichlorophenol, respectively. Parent compound comprised 1.5, 2.7, and 0.7% of total14C for phenol, 2,4,5-trichlorophenol, andp-nitrophenol, respectively, after 28 days of depuration.