Environmental Toxicology and Chemistry

MacIorowski, Anthony F.

doi: 10.1002/etc.5620070901pmid: N/A

Pratt, J. R.; Bowers, N. J.; Niederlehner, B. R.; Cairns, J.

doi: 10.1002/etc.5620070902pmid: N/A

Laboratory microcosms and field enclosures were used to evaluate effects of chlorine on microbial community structure and function. Microcosms were exposed to chlorine (as sodium hypochlorite) at concentrations up to 308 μg/L total residual chlorine (TRC) for 28 d. Test systems were sampled weekly to evaluate protozoan species accrual, biomass distribution, microbial enzyme activity, and macronutrient retention. Protozoan species numbers were depressed at all sampling times at TRC concentrations ≥25 μg/L. Algal biomass (chlorophyll a) was adversely affected at 2 μg/L, and alkaline phosphatase activity was inhibited at ≥6 μg/L. Other biomass measures and macronutrient retention were affected at 25 to 308 μg/L. Oxygen production was depressed at ≥25 μg/L. Field enclosures (sediment‐water mesocosms) were dosed daily with chlorine, resulting in average chlorine doses up to 261 μg/L. Protozoan species numbers were depressed at chlorine doses ≥79 μg/L, and zooplankton density was affected at 24 μg/L. Algal biomass and total biomass were adversely affected at the highest chlorine level, 261 μg/L. Nontaxonomic measures were typically less sensitive than community structure responses to chronic chlorine stress. Estimated effect levels for both experiments overlapped; however, the response of specific variables (i.e., stimulation, inhibition, no effect) to chlorine differed between the two tests. These results support the importance of experimental design and dosage regime in chronic toxicity testing.

Layher, William G.; Maughan, O. Eugene

doi: 10.1002/etc.5620070903pmid: N/A

Standing stocks of fish species were graphed against 30 abiotic variables measured in Kansas streams. The resulting habitat suitability curves for each variable allowed fish biomass to be normalized to index values that could be regressed linearly against these variables. Stepwise multiple‐regression techniques isolated variables that accounted for much of the biomass of individual populations. Regression models applied to an independent data set from Oklahoma produced highly significant (though low) correlations between predicted and observed standing stocks. Assigning suitability index values to Oklahoma streams from curves developed with Kansas data identified other variables as limiting, thus explaining much of the biomass variation. This analysis indicated that the habitat suitability curves approximated fish population changes along a single‐variable axis. Kansas stream data has been placed in a statistical data set and provided with visual display. The system allows for rapid assessment of the effects of changes in 30 physicochemical variables on populations of about 100 fish species in Kansas streams.

Farris, Jerry L.; Van Hassel, John H.; Belanger, Scott E.; Cherry, Donald S.; Cairns, John

doi: 10.1002/etc.5620070904pmid: N/A

Rigorous testing schemes in field‐located artificial streams and in‐stream monitoring provided evidence for use of Corbicula cellulolytic activity as a highly sensitive and efficient approach to effluent assessment. Cellulolytic (exo‐ and endocellulase) activity of the Asiatic clam, Corbicula sp., determined in 30‐d, field‐located artificial stream exposures at the New River, Virginia to single components of power plant effluents (copper [Cu] and zinc [Zn] separately) was compared with cellulolytic responses in caged clams from within an impacted area of the Clinch River, Virginia below power plant effluents. Cellulolytic responses were then compared to conventional biomonitoring responses (Hester‐Dendy macroinvertebrate community structure), water quality monitoring in the Clinch River, and laboratory artificial stream bioassays. Clam enzyme activity was significantly reduced in 10 to 20 d (α = 0.05) at 16 and 87 μg Cu and Zn/L, respectively, in field‐located artificial streams. Cellulolytic activity of clams caged at stations within power plant outfalls (metal concentrations of 47–78 μg Zn/L and 80–345 μg Cu/L) was significantly reduced to levels as low as 9 to 52% of upstream activity levels. Reduction in cellulolytic activity in Corbicula was more sensitive after 14 d of in‐stream monitoring than reduction in diversity of macroinvertebrate assemblages after 28 d. Bioassay exposures as long as 30 d were needed to provide toxicity data comparable to enzyme impairment seen as early as 10 d.

Clements, William H.; Cherry, Donald S.; Cairns, John

doi: 10.1002/etc.5620070905pmid: N/A

The effects of copper on aquatic insect communities were examined using rock‐filled trays colonized in the field for 30 d, transferred to laboratory streams, and dosed with CuSO4. Each stream was randomly assigned to one of three treatments: control (0 μg/L), low dose (15–32 μg/L), and high dose (135–178 μg/L). Experiments were replicated over three seasons. Exposure to copper for 96 h significantly reduced both the total number of individuals and number of taxa during each season, with greatest effects observed in summer. Owing to differences in sensitivity to copper, the percent composition of dominant orders of aquatic insects varied among treatments. The relative abundance of Ephemeroptera decreased in treated streams during each season. The response of other aquatic insects, including Diptera and Plecoptera, varied between seasons, but these groups were generally less sensitive to copper exposure. These results indicate that the artificial substrates employed in this study are amenable to experimental manipulation and will provide a unique opportunity to examine the community responses of aquatic insects to toxicants under environmentally realistic conditions.

Genter, Robert B.; Cherry, Donald S.; Smith, Eric P.; Cairns, John

doi: 10.1002/etc.5620070906pmid: N/A

Attached‐algal communities were employed to test the U.S. Environmental Protection Agency's (EPA) guidelines for zinc (Zn) and pH. The EPA criterion for Zn is 0.047 mg/L, and the EPA effluent standard generally requires that discharge water fall between pH 6 and 9. The experiment was designed to determine whether algal community composition and abundance would be altered by (a) pH 6 or 9, (b) 0.05 mg/L Zn, or (c) the combination of pH 6 or 9 and 0.05 mg/L Zn. Stream mesocosms were continuously supplied with natural water from the New River, Virginia, USA. Established (12‐d colonization) communities on artificial substrates were sampled on days 0, 5, 10, 20, and 30 after treatment began on 9 July 1985. Total algal abundance increased in pH 6 treatment. Treatments of pH 6 and 0.05 mg/L Zn reduced abundance of species characteristic of control mesocosms. These species were replaced by species characteristic of 0.05 mg/L Zn and pH 6 mesocosms. These changes occurred even though these levels are considered “safe” by EPA. Community composition did not differ significantly between ambient (pH 8.5) and pH 9 treatments. Although further research is needed, one might speculate that this change in community composition may have potential ecosystem effects by reducing food quality from diatoms to green algae that may inhibit higher level consumers.

Christensen, Sigurd W.; Breck, James E.; Van Winkle, W.

doi: 10.1002/etc.5620070907pmid: N/A

We developed a framework of linked models that uses lake levels of pH, Al, and Ca to predict the occurrence of fish species on a regional scale. As a first step, statistical models are fitted to laboratory data on brook trout (Salvelinus fontinalis). The resulting functions predict mortality and reduction in fecundity resulting from chemical conditions (pH, Al, and Ca). The second step applies a life‐cycle model to results from the first step to estimate the reproductive potential expected for fish living in lakes with specified chemical conditions relative to that expected for fish living under nonstressful chemical conditions. Use of the framework requires field data on the presence or absence of brook trout in lakes having measured pH, Al, and Ca. The chemical conditions for each lake are processed through the first two steps to estimate the relative reproductive potential for brook trout in that lake. After, obtaining estimates for all lakes, a logistic regression model is fitted, with probability of occurrence as the dependent variable and relative reproductive potential as the independent variable. The resulting function, representing the calibrated framework, relates the probability of brook trout occurrence in high‐elevation Adirondack (New York) lakes to relative (i.e., reduced) reproductive potential attributable to chemical stress. This function, when tested against additional data, can be used to predict changes in brook trout population status in relation to changed chemical conditions, stocking, or altered fishing pressure.

Belisle, Andre A.; Swineford, Douglas M.

doi: 10.1002/etc.5620070908pmid: N/A

A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetonermethylene chloride (1:1, v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93% for sediments extracted shortly after spiking, but decreased significantly as the samples aged.

Poston, Ted M.; Bean, Roger M.; Kalkwarf, Donald R.; Thomas, Berta L.; Clark, Mark L.; Killand, Bruce W.

doi: 10.1002/etc.5620070909pmid: N/A

Photooxidation of smoke generator fuel (SGF) No. 2 fog oil was investigated to determine qualitative changes in the chemistry of the oil and the resulting acute toxicity to the freshwater amphipod Hyallela azteca. The 48‐h LC50 was about 11.5 mg total oil/L for photooxidized fog oil. Toxicity was related to the greater solubility of photooxidized fog oil in that higher concentrations of total dissolved oil in oil‐water mixtures were obtained after equivalent additions of photooxidized oil and nonphotooxidized oil. Photooxidation caused increases in carbonyl oxygen and the presence of alpha‐ and beta‐unsaturated ketones and acetophenones in aqueous extracts. There was no evidence for the formation of phenolic compounds in the photooxidized fog oil or in oil‐water mixtures.

Hendry, Karen M.; Richardson, Curtis J.

doi: 10.1002/etc.5620070910pmid: N/A

A field application level (9 μg·g−1) of carbofuran was completely hydrolyzed within 1 to 3 days in a loamy sand soil pretreated with the same level of carbofuran, while <5% of the carbofuran was hydrolyzed in control soil not pretreated. The number of microbial carbofuran‐hydrolyzers was substantially greater in loamy sand soil treated twice with a field application level (9 μg·g−1) of carbofuran than in untreated soil. Also, carbofuran‐adapted soil showed no significant change in the number of carbofuran‐hydrolyzers during the period of rapid degradation. Inorganic nitrogen, at a typical fertilization level, appeared to slightly stimulate the enhanced degradation of carbofuran in the pretreated soil. Soil pretreated with an application level hydrolyzed 65% of a residue level (8 ng·g−1) within two days, but virtually none of the remaining carbofuran was hydrolyzed thereafter. A microbial biomass carbon experiment with a sandy loam soil indicated that only 0.2% of the applied carbonyl‐C could be attributed to biomass. Soil pretreated with a residue level did not show rapid degradation of the same level or a field application level, although the field application level was degraded slightly faster in this soil than in soil not pretreated. Soil pretreated with a field application level of carbofuran or furathiocarb also rapidly hydrolyzed the same level of furathiocarb, but furathiocarb is probably converted into carbofuran before hydrolysis.