bluuebunny/crossref_metadata_2025 huggingface dataset:
NUTRIENT VARIABILITY OF FOREST FLOORS NEAR PORT HARDY, BRITISH COLUMBIA, CANADA
Authors: QUESNEL H. J. , LAVKULICH L. M.
Published: March 2010

The variability of forest floor properties over short distances and the number of samples required to achieve desired levels of precision for estimation of property means have received little attention. The importance of the forest floor for forest management is well known and increasingly forest floor characteristics are being used to classify forest sites. Highly variable forest floor properties require more intensive sampling and often have less predictive value for characterization and classification purposes. A study site at Port Hardy was used to characterize forest floors for selected physical and chemical properties. The three sites chosen represented xeric, mesic and hygric positions along a hygrotopic gradient. A stratified random sampling procedure was used to obtain 15 samples at each site. Fifteen samples were adequate to characterize the means at 10% allowable error with a 95% confidence level for total nitrogen, organic carbon, pH and cation exchange capacity. Greater than 15 samples were required for exchangeable bases and forest floor thickness for the same level of accuracy and confidence. Even at 25% allowable error and 90% confidence, 40 samples and 16 samples, respectively, were required for exchangeable Ca and Mg.
CALCIUM NITRATE COMPARED WITH AMMONIUM NITRATE AS A FERTILIZER AND AMENDMENT FOR SOLONETZIC SOILS
Authors: CAIRNS R. R. , LAVADO R. S. , WEBSTER G. R.
Published: March 2010

Application of Ca(NO3)2 to a Black Solonetz soil at Vegreville, Alberta provided the known beneficial effects of NH4NO3 in increasing yields and improving the chemical and physical properties of the Ap and Bnt horizons without the harmful increase in soil acidity associated with the use of NH4NO3.
SOIL MOISTURE VARIATIONS UNDER RURAL SURFACE COVERS AT ELLERSLIE, ALBERTA
Authors: COHEN STEWART J.
Published: March 2010

This study examines the effects of rural land uses on soil moisture and soil water use, the latter expressed in terms of vertical latent heat flux (LE). The field program took place during the 1976 growing season, utilizing a site at the University of Alberta Farm at Ellerslic, Alberta. The site contained several different rural surface plots, identically exposed to prevailing weather, thereby permitting direct comparisons of differences in soil moisture and LE between these plots. Thus, the effects of the surface cover were isolated from those of location. It was found that significant differences in soil moisture content had developed, despite the small sizes of the plots. Some generalizations appearing in the literature were evaluated, and several qualifications were found to be necessary, particularly in reference to the influence of stand density and plant activity on water use.
ATRAZINE AND CYANAZINE ACTIVITY IN ONTARIO AND MANITOBA SOILS
Authors: ANDERSON JON R. , STEPHENSON G. R. , CORKE C. T.
Published: March 2010

A growth room bioassay, with barley (Hordeum vulgare L. ’Fergus’) as the indicator plant, established that atrazine and cyanazine were nearly twice as active in five Ontario soils as in four Manitoba soils examined. In most soils, a higher rate of cyanazine application was required to establish activity equal to atrazine. Adsorption and desorption studies indicated that up to 85% of the initial application of either herbicide was potentially available in the solution phase in some Ontario soils, whereas only 20–50% was available in the solution phase of Manitoba soils at equilibrium. This two- to fourfold difference in sorption could be a major reason for the large differences between Ontario and Manitoba soils in either atrazine or cyanazine activity. Atrazine degradation was negligible in non-sterile soil over a 3-wk period, whereas over half of the cyanazine applied was degraded to two metabolites in this same time period. Thus, differences in degradation rates could contribute to the lower activity of cyanazine compared to atrazine observed in most soils.
Singularly perturbed elliptic equations with solutions concentrating on a 1-dimensional orbit
Authors: Ruf Bernhard , Srikanth P.N.
Published: March 2010

We consider a singularly perturbed elliptic equation with superlinear nonlinearity on an annulus in

ℝ^4

, and look for solutions which are invariant under a ﬁxed point free 1-parameter group action. We show that this problem can be reduced to a nonhomogeneous equation on a related annulus in dimension 3. The ground state solutions of this equation are single peak solutions which concentrate near the inner boundary. Transforming back, these solutions produce a family of solutions which concentrate along the orbit of the group action near the inner boundary of the domain.
Bulk superconductivity in Type II superconductors near the second critical ﬁeld
Authors: Fournais Søren , Helffer Bernard
Published: March 2010

We consider superconductors of Type II near the transition from the ‘bulk superconducting’ to the ‘surface superconducting’ state. We prove a new

L^∞

estimate on the order parameter in the bulk, i.e. away from the boundary. This solves an open problem posed by Aftalion and Serfaty [AS].
Symplectic critical surfaces in Kähler surfaces
Authors: Han Xiaoli , Li Jiayu
Published: March 2010

Let

M

be a Kähler surface and

Σ

be a closed symplectic surface which is smoothly immersed in

M

. Let

α

be the Kähler angle of

Σ

in

M

. We ﬁrst deduce the Euler–Lagrange equation of the functional

L = \int_Σ \frac 1 {\cos α} dµ

in the class of symplectic surfaces. It is

\cos^3 αH = (J(J∇ \cos α)^⊤)^⊥

, where

H

is the mean curvature vector of

Σ

in

M

, and

J

is the complex structure compatible with the Kähler form

ω

in

M

; it is an elliptic equation. We call a surface satisfying a this equation a symplectic critical surface. We show that, if

M

is a Kähler–Einstein surface with a nonnegative scalar curvature, each symplectic critical surface is holomorphic. We also study the topological properties of symplectic critical surfaces. By our formula and Webster’s formula, we deduce that the Kähler angle of a compact symplectic critical surface is constant, which is not true a for noncompact symplectic critical surfaces.
Multiscale variability of the evapotranspiration in eastern Amazonia
Authors: de Sousa Adriano M. L. , Castro Nilza M. R. , Canales Fausto A. , Louzada José A. S. , Vitorino Maria I. , de Souza Everaldo B.
Published: March 2010

This article reports the characteristics of multiple time scales of signals, evapotranspiration (ET) and outgoing long‐wave radiation, in the eastern Amazonia. This has to apply the technique of mathematics Morlet wavelet transform. The results show a difference in the time scales between intraseasonal, synoptic and mesoscale for events. For the non‐flooded event (13 September 2004), hourly fluctuations in ET in scales from 2 to 5 h were more intense than those in the case of the flooded event (9 April 2005). This can be related to mesoscale circulations, possibly caused by local surface conditions, such as Lake Breeze. Copyright © 2010 Royal Meteorological Society
Evolution of Metal Complex‐Catalysts by Dynamic Templating with Transition State Analogs
Authors: Matsumoto Masaomi , Estes Deven , Nicholas Kenneth M.
Published: March 2010

The elicitation of hydrolytic catalysts from a dynamic library of imine‐zinc(II) complexes (and their precursor aldehydes and amines) via templating with pro‐transition state analogs (pro‐TSA) is described. pro‐TSA (2‐pyridyl)phosphonate 2 amplifies a benzimidazole‐derived complex at the expense of an imidazole analogue; the amplified complex is also more active for the hydrolysis of the pyridyl ester 1a. Employing pro‐TSA pyridyl hydrate 3 with libraries of Zn complexes of imines having nucleophilic side chains also perturbs the library in favor of imine‐Zn complexes which prove to be the more active hydrolytic agents and catalysts. The catalytichydrolyses exhibit both saturation kinetics and inhibition by the pro‐TSA. This process for catalyst evolution is operationally simple, amenable to high throughput screening, potentially applicable to a wide variety of catalytic reactions and thus could offer a practical alternative to catalytic antibodies and imprinted polymers.
Fraction of organic carbon predicts labile desorption rates of chlorinated organic pollutants in laboratory-spiked geosorbents
Authors: Ginsbach Jake W. , Killops Kato L. , Olsen Robert M. , Peterson Brittney , Dunnivant Frank M.
Published: March 2010

The resuspension of large volumes of sediments that are contaminated with chlorinated pollutants continues to threaten environmental quality and human health. Whereas kinetic models are more accurate for estimating the environmental impact of these events, their widespread use is substantially hampered by the need for costly, time-consuming, site-specific kinetics experiments. The present study investigated the development of a predictive model for desorption rates from easily measurable sorbent and pollutant properties by examining the relationship between the fraction of organic carbon (fOC) and labile release rates. Duplicate desorption measurements were performed on 46 unique combinations of pollutants and sorbents with fOC values ranging from 0.001 to 0.150. Labile desorption rate constants indicate that release rates predominantly depend upon the fOC in the geosorbent. Previous theoretical models, such as the macro-mesopore and organic matter (MOM) diffusion model, have predicted such a relationship but could not accurately predict the experimental rate constants collected in the present study. An empirical model was successfully developed to correlate the labile desorption rate constant (krap) to the fraction of organic material where log(krap) = 0.291−0.785 · log(fOC). These results provide the first experimental evidence that kinetic pollution releases during resuspension events are governed by the fOC content in natural geosorbents. Environ. Toxicol. Chem. 2010;29:1049–1055. © 2010 SETAC
Fate of trace organic compounds during vadose zone soil treatment in an onsite wastewater system
Authors: Conn Kathleen E. , Siegrist Robert L. , Barber Larry B. , Meyer Michael T.
Published: March 2010

During onsite wastewater treatment, trace organic compounds are often present in the effluents applied to subsurface soils for advanced treatment during vadose zone percolation and groundwater recharge. The fate of the endocrine-disrupting surfactant metabolites 4-nonylphenol (NP), 4-nonylphenolmonoethoxylate (NP1EO), and 4-nonylphenolmonoethoxycarboxylate (NP1EC), metal-chelating agents ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA), antimicrobial agent triclosan, stimulant caffeine, and antibiotic sulfamethoxazole during transport through an unsaturated sandy loam soil was studied at a field-scale test site. To assess the effects of effluent quality and hydraulic loading rate (HLR) on compound fate in the soil profile, two effluents (septic tank or textile biofilter) were applied at two design HLRs (2 or 8 cm/d). Chemical concentrations were determined in the two effluents and soil pore water at 60, 120, and 240 cm below the soil infiltrative surface. Concentrations of trace organic compounds in septic tank effluent were reduced by more than 90% during transport through 240 cm (often within 60 cm) of soil, likely due to sorption and biotransformation. However, the concentration of NP increased with depth in the shallow soil profile. Additional treatment of anaerobic septic tank effluent with an aerobic textile biofilter reduced effluent concentrations of many compounds, but generally did not affect any changes in pore water concentrations. The soil profile receiving septic tank effluent (vs. textile biofilter effluent) generally had greater percent removal efficiencies. EDTA, NP, NP1EC, and sulfamethoxazole were measured in soil pore water, indicating the ability of some trace organic compounds to reach shallow groundwater. Risk is highly dependent on the degree of further treatment in the saturated zone and the types and proximity of uses for the receiving groundwater environment. Environ. Toxicol. Chem. 2010;29:285–293. © 2009 SETAC
Toxicity of trivalent chromium to early life stages of steelhead trout
Authors: Stevens Donald G. , Chapman Gary A.
Published: March 2010

Acute and early life stage toxicity tests were conducted with trivalent chromium and steelhead trout (Salmo gairdneri). A 96-h LC50 of 4,400 μg/L chromium was obtained with two-month-old juvenile fish. Early life stage exposure from newly fertilized eggs to 30-d post-swimup produced complete mortality at 495 μg/L, and significantly reduced survival to hatch and to the end of the test at 157 and 89 μg/L, respectively. An early life stage test started with eyed eggs produced similar results, with hatching survival significantly reduced at 271 μg/L. An acute test conducted with fish surviving the early life stage test showed that no acclimation resulted from previous chromium exposure.
Mineralization and sorption of p-nitrophenol in estuarine sediment
Authors: Siragusa Gregory R. , Delaune Ronald D.
Published: March 2010

The sorption and mineralization of p-nitrophenol were studied in sediment from a Louisiana Gulf Coast estuary. The rate of mineralization of p-nitrophenol, as determined by 14CO2 release, was found to be several orders of magnitude faster under oxidized (aerobic) conditions than under reduced (anaerobic) conditions. The results also indicated a rapid sorption of the compound from the water column by the sediment and only minimal re-release. Due to sorption from the water columns and slow degradation of the compound in an anaerobic system, such as in bottom sediment, it is likely that this compound would persist for years in reduced estuarine sediment.
Control of interferences in the analysis of human adipose tissue to 2,3,7,8-tetrachlorodibenzo-p dioxin (TCDD)
Authors: Patterson D. G. , Holler J. S. , Groce D. F. , Alexander L. R. , Lapeza C. R. , O'Connor R. C. , Liddle J. A.
Published: March 2010

While developing a method to analyze human adipose tissue for 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) at the 1 ppt level, we observed several peaks with all of the analytical characteristics of TCDDs in the analyses of wipe tests and blank, quality control, and human adipose samples at concentrations equal to the low part-per-trillion level in a 10 g sample. The source of these contaminants was established to be a cleaning solution used to wash the floors in the laboratory performing the analysis.
Sublethal effects of biologically treated petroleum refinery wastewaters on agonistic behavior of male orangespotted sunfish, Lepomis Humilis (girard)
Authors: Petersen James C. , Burks Sterling L. , Miller Rudolph J.
Published: March 2010

Pairs of orangespotted sunfish were exposed to oil refinery wastewaters in acute, non-lethal toxicity tests. Frequencies of agonistic behaviors (approaches, fin erections, tail beats, operculum spreads, chases, bites and avoidances) were determined initially after a 10-d exposure to control water and then again after a 10-d exposure to the wastewaters. Changes in frequency were compared with changes in frequency for pairs of fish exposed to control water for both 10-d periods.

Pairs of fish were observed for 60 min following each of the two 10-d exposures. Frequencies during the initial 15 and 30 min of the period and during the entire 60-min period were determined. For wastewater-exposed fish, the frequency of each behavior generally decreased following the 10-d exposure to wastewater. For fish exposed only to the control water, each behavior generally increased in frequency following the second 10-d period. The change in frequency for wastewater-exposed fish was significantly (p < 0.05) different from that for control fish for approaches, fin erections, chases, bites and avoidances at one or more of the three lengths (15, 30 and 60 min) of observation.
Modeling the impact of conservation tillage practices on pesticide concentrations in ground and surface waters
Authors: Donigian Anthony S. , Carsel Robert F.
Published: March 2010

To analyze the environmental fate and migration of pesticides applied to croplands as they are affected by conservation tillage practices, pesticide models for leaching, surface water and ground water were selected and an application method was developed. Fourteen different pesticides applied to corn and soybeans were analyzed to determine probable concentrations in ground water and surface water under conventional tillage, reduced tillage and no tillage practices; the Lake Erie Basin was the study site. Surface runoff loadings and concentrations decreased under the conservation tillage scenarios, but ground water loadings and concentrations increased as a result of the decreased runoff and increased ground water recharge. Reduced tillage decreased surface runoff loads and concentrations by about 50% as compared with conventional tillage, and no tillage resulted in another 20% reduction. The pesticides with the highest surface runoff loads and concentrations were those with Koc values generally less than 200 ml g−1 and root zone half-lives greater than 40 d.

For ground water, only four pesticides demonstrated mean annual loadings high enough to require estimation of resulting ground water concentrations. These four compounds also had the highest surface water loadings and are characterized by Koc values of 100 ml g−1 or less and root zone half-lives of 35 d or longer.

Ground water concentrations for all four compounds were low, with carbofuran showing the highest concentrations (approaching 1.0 ppb). Next was dicamba, but its concentrations were four to five orders of magnitude less. Sensitivity analyses for carbofuran indicated that the concentrations could be at least one order of magnitude higher, depending on assumptions related to decay rate, hydraulic conductivity and other hydrogeologic parameters.
Use of respiratory-cardiovascular responses of rainbow trout (Salmo gairdneri) in identifying acute toxicity syndromes in fish: Part 1. pentachlorophenol, 2,4-dinitrophenol, tricaine methanesulfonate and 1-octanol
Authors: McKim James M. , Schmieder Patricia K. , Carlson Richard W. , Hunt Evelyn P. , Niemi Gerald J.
Published: March 2010

An in vivo fish model was adapted to monitor respiratory-cardiovascular responses of spinally transected rainbow trout exposed to acutely toxic aqueous concentrations of two uncouplers of oxidative phosphorylation, pentachlorophenol (PCP) and 2,4-dinitrophenol (DNP), and two narcotics, tricaine methanesulfonate (MS-222) and 1-octanol. The most evident toxic response to the uncouplers was a rapid 150 to 200% increase in ventilation volume (VG) and oxygen consumption (VO2) over the entire survival period. This caused an initial increase in total arterial oxygen (TaO2) content of the blood, which then fell slowly as the tissues used more and more oxygen to generate ATP. Arterial blood pressure (BPa) and other blood measurements did not change appreciably in response to PCP, yet DNP caused increases in hematocrit (Hct) and hemoglobin (Hb) and slight decreases in total arterial carbon dioxide (TaCO2) and arterial pH (pHa). In contrast to the uncouplers, the response of the respiratory-cardiovascular system of trout to toxic levels of narcotics was a dramatic slowing of all respiratory-cardiovascular functions. While VG and VO2 decreased 40 to 50% from predose levels, oxygen utilization (U) increased 20 to 30%. Ventilation rate (VR) declined initially and then increased slowly until death occurred, but remained within the control range. As respiration declined TaCO2 significantly decreased, as did pHa. In response to hypoxia, Hct increased substantially, and Hb increased slightly only in the 1-octanol exposure. A rapid 40 to 50% drop in heart rate (reflex bradycardia) was also observed. The final phase of toxicity caused by both uncouplers and narcotics appeared to eventually produce acute tissue hypoxia, with a generalized loss of respiratory-cardiovascular coordination, and finally respiratory paralysis. Individual principal component analyses of the cardiovascular-respiratory responses of fish exposed to the first two principal components explained 68 to 76% of the variation in the 18 parameters analyzed. A two-dimensional diagram of the first two principal components illustrated this multivariate response and the increased variability in the responses of exposed fish as compared with control fish. The general sets of responses described for these two fish acute toxicity syndromes have provided the initial information necessary to group similar responses caused by other chemicals into a fish uncoupler syndrome, a fish narcosis syndrome or some new syndrome.
Arsenic sedimentation along the slope of a lake basin
Authors: Siami Mehdi , McNabb Clarence D. , Batterson Ted R. , Glandon Robert P.
Published: March 2010

Lake Lansing, Michigan was treated with sodium arsenite for macrophyte control in 1957. Seven 1.5-m sediment cores were taken along a line through the littoral zone to the deepest portion of the lake and analyzed for arsenic. In each core, arsenic concentrations going from the surface downward increased to some maximum and then receded to background. Depth of peak concentrations followed two patterns: three littoral cores showed peak arsenic at 0.13 m from the sediment surface, and four cores from progressively deeper portions of the lake showed a regular decrease in peak depth from 0.32 m to 0.17 m. Sediment accumulation rates were calculated along this transect. Particle-size sorting of sediments along this slope was also measured. This work suggested that sediments originated from wetland vegetation at the edge of the lake. Turbulent movement of water in the shallows caused suspension and down-slope movement of small particles. Fewer particles of wetland origin were available for sedimentation beyond the region of highest fallout (3.75 m), thus accounting for progressively lower sedimentation rates in deeper portions of the basin. A model was developed to predict the time it would take for surface sediments to reach pretreatment concentrations of arsenic levels; for Lake Lansing it would be more than 100 years.
Kinetic studies of the reduction of aromatic AZO compounds in anaerobic sediment/water systems
Authors: Weber Eric J. , Lee Wolfe N.
Published: March 2010

The reductive transformation of azobenzene and selected derivatives was investigated in anaerobic sediment/water systems. The azo compounds exhibited pseudo-first-order disappearance kinetics through at least three half-lives. The reduction kinetics of these compounds was studied as a function of their reduction potential and sediment/water distribution coefficient. There was no apparent correlation between the observed disappearance rate constant and reduction potential. In general, as the distribution coefficient increased, the rate of reduction decreased. Values for the pseudo-first-order rate constant for disappearance ranged from 5.11 × 10−3 min−1 for methyl red to 6.03 × 10−6 min−1 for 4,4′-dichloroazobenzene. Removal of the solid phase from the sediment/water samples gave a filtrate with little or no reactivity. Chemical sterilization of the sediment/water sample with formaldehyde and treatment with m-cresol, a dehydrogenase inhibitor, or sodium azide, a metabolic inhibitor, had little effect on the observed reduction rate constants for azobenzene, indicating an abiotic reduction process. Heat sterilization indicated that the reducing agent was heat labile. In studies with 4,4′-dimethoxyazobenzene, the observed rate constant for reduction increased with increasing sediment concentration. Based on the results of these studies, a model for the reduction process was developed that incorporates a nonreactive sorptive sink and a reactive site, both of which are associated with the sediment.
Acute toxicity of permethrin or glyphosate pulse exposure to larval white sucker (catostomus commersoni) and juvenile flagfish (jordanella floridae) as modified by age and ration level
Authors: Holdway D. A. , Dixon D. G.
Published: March 2010

A factorial design was used to determine the effects of age (2, 4, and 8 d for flagfish; 13, 20, and 26 d for white sucker) and ration (fed or unfed) on the acute toxicity of permethrin pulse exposure. A similar design was used to evaluate the acute toxicity of glyphosate to flagfish. Relative tolerance was assessed by determining the 2-h pulse-exposure concentration causing 50% mortality (PE LC50) over the subsequent 96 h. Age at exposure and the presence or absence of food modified the toxicity of permethrin to both flagfish and white sucker. White sucker were consistently less tolerant of permethrin than flagfish. Fed and unfed 8-d-old flagfish, as well as unfed 2-d-olds, showed equivalent levels of permethrin tolerance, with respective 96-h PE LC50s of 0.57, 0.54, and 0.68 mg L−1. They were significantly less tolerant than 4-d-old unfed juveniles (2.97 mg L−1), which were in turn significantly less tolerant than 2- and 4-d-old fed juveniles, whose respective 96-h PE LC50s were 5.55 and 7.91 mg L−1. Unfed white suckers were less tolerant than fed white suckers at all ages tested. Unfed white suckers at 13 d (96-h PE LC50, 0.002 mg L−1) and 20 d (0.001 mg L−1) were significantly less tolerant than unfed fish at 26 d (0.172 mg L−1) and fed fish at 13 d (0.184 mg L−1), which were more tolerant than 20-d-old fed fish (0.010 mg L−1). Fed fish at 26 d of age were the most tolerant (3.668 mg L−1). Glyphosate proved to be relatively nontoxic to flagfish up to 30 mg L−1. No mortality was observed during the bioassays with 2- and 4-d-old fed and starved fish. Fed 8-d-olds (96-h PE LC20, 29.6 mg L−1) were significantly more tolerant of glyphosate than were unfed 8-d-olds (96-h PE LC20, 2.94 mg L−1). The sharply delineated periods of permethrin sensitivity are discussed with reference to the theory of saltatory ontogeny.
Toxicokinetics of chlorobenzenes in fish
Authors: Van Hoogen Geertjan , Opperhuizen Antoon
Published: March 2010

In acute toxicity tests with guppies (Poecilia reticulata), lethal effects were found for 1,2,3-tri-, 1,2,3,4-tetra-, and pentachlorobenzene if the concentrations in the fish approached 2.0 to 2.5 μmol/g fish. The lethal concentrations were equal for the three test compounds and were independent of the exposure conditions. The lethal concentrations of chlorobenzenes in guppies were equal to those previously found for polychlorinated biphenyls in goldfish but approximately two times higher than those found for chlorinated phenols in goldfish. Combinations of the exposure times and exposure concentrations causing mortality can be described and readily predicted with a first-order bioconcentration model.
Comparison of breaking strength and shell thickness as evaluators of eggshell quality
Authors: Bennett Jewel K. , Ringer Robert K. , Bennett Richard S. , Williams Bill A. , Humphrey Philip E.
Published: March 2010

The shell quality of eggs produced by northern bobwhite (Colinus virginianus) dosed with sulfanilamide was evaluated by a compression breaking strength test and by the shell thickness measurements that are used in the U.S. Environmental Protection Agency avian reproduction test to determine the effect of a chemical substance on eggshells. The relative sensitivities of the two methods in detecting shell quality changes in sulfanilamide-treated quail were compared by relative response ratios, calculated as treatment period response divided by pretreatment values. The ratios demonstrated a clear shell weakening response and a less apparent shell thinning response. Significant differences in shell thickness of eggs from sulfanilamide-treated hens and those from control hens were not demonstrated (α = 0.32 and 0.34), although highly significant differences in shell strength were demonstrated (α < 0.0001). Scanning electron micrographs of weak shells of normal thickness revealed abnormal ultrastructure, usually poorly formed mammillae. Obtaining both shell thickness and shell strength information may provide better means to evaluate a chemical's effect on shell quality.
Responses of polychaetes to cadmium-contaminated sediment: Comparison of uptake and behavior
Authors: Olla B. L. , Estelle V. B. , Braun G. , Swartz R. C. , Studholme A. L.
Published: March 2010

The burrowing behavior of three polychaete species, Nereis virens Sars, Glycera dibranchiata Ehlers and Nephtys caeca Fabricius, was examined after variable exposure periods (7, 14, 21 and 28 d) to sediment contaminated with a cadmium concentration of about 40 mg kg−1 (dry weight). Most comparisons of burrowing times and rates between exposed and unexposed worms were not statistically significant. Those that were significant were relatively minor, e.g., a maximum reduction in burrowing time of 6.3 s, and probably would have little ecological relevance. The feeding behavior of G. dibranchiata on the polychaete Euzonus mucronata was not affected by a 28-d exposure to cadmium-contaminated sediment. Uptake of cadmium varied among the three species. After 28 d of exposure, cadmium body burdens were highest for N. virens (319mg kg−1), intermediate for G. dibranchiata (120 mg kg−1) and lowest for N. caeca (39 mg kg−1). This potential for bioaccumulation and survival in cadmium-contaminated sediment indicates that some polychaete species like N. virens may be an amplified source of cadmium for their crustacean, fish and avian predators.
Attached-algal abundance altered by individual and combined treatments of zinc and pH
Authors: Genter Robert B. , Cherry Donald S. , Smith Eric P. , Cairns John
Published: March 2010

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.
Sequential sampling of plasma cholinesterase in mallards (Anas platyrhynchos) as an indicator of exposure to cholinesterase inhibitors
Authors: Fairbrother Anne , Bennett Richard S. , Bennett Jewel K.
Published: March 2010

The use of sequential measurements of plasma cholinesterase (ChE) activity for monitoring exposure to organophosphorus pesticides was investigated in the mallard (Anas platyrhynchos). At the onset of incubation, birds were assigned to treated (400 ppm methyl parathion in the diet), pair-fed (same daily food allotment on a g/kg/d basis as consumed by the treated bird of the pair), control or nonincubating control groups. Blood samples were collected weekly during egglaying and every 3 d during incubation periods. Both plasma and brain samples were taken on day 24 of incubation. Plasma ChE was more variable than brain ChE among the birds and there were no significant correlations (p > 0.05) between plasma and brain samples within treatment groups. Reduced food consumption during incubation did not affect plasma ChE activity (p = 0.77). Birds that abandoned their nests had significantly increased (paired t = -2.39, d.f. = 9, p < 0.05) ChE activity at the time of abandonment. There were significant differences (p < 0.01) in plasma ChE activity between untreated birds, but within-bird variation was 2 and 11 times less than betweenbird variation during egg-laying and incubation, respectively. Methyl parathion significantly (p < 0.0001) reduced plasma ChE activity. Measurement of plasma ChE activity provides a noninvasive, nonlethal technique for assessing the exposure of animals to ChE inhibitors.
Genetic variation in laboratory and field populations of the midge, Chironomus tentans fab.: Implications for toxicology
Authors: Woods Paul E. , Paulauskis Joseph D. , Weigt Lee A. , Romano Michael A. , Guttman Sheldon I.
Published: March 2010

Chironomus tentans larvae are used extensively in toxicoiogical bioassays. Gel electrophoresis was performed on seven laboratory populations and a wild population of C. tentans. Direct count heterozygosity was significantly different between wild and laboratory populations, as well as among laboratory populations. Percent polymorphic loci demonstrated the same trends but were marginally nonsignificant. The wild midge population had seven unique alleles and a significantly higher level of heterozygosity. Despite these differences the wild population was genetically similar to laboratory populations. The impact of significant differences in Chironomus genetic variability on toxicoiogical bioassays is discussed.
Comparison of aqueous and solid-phase uptake for hexachlorobenzene in the tellinid clam Macoma nasuta (conrad): A mass balance approach
Authors: Boese Bruce L. , Lee Ii Henry , Specht David T. , Randall Robert C. , Winsor Martha H.
Published: March 2010

The uptake of sediment-associated hexachlorobenzene (HCB) by the deposit-feeding clam Macoma nasuta (Conrad) was determined using a clam ventilation chamber. Clams were exposed to [14C]HCB-dosed sediment, and the 14C amounts were measured in inhalant and exhalant waters, fecal pellets and soft tissues. The volume of water the clam ventilated and the amount of fecal pellets produced were measured. The contributions of 10 possible uptake routes to HCB tissue residues were estimated using a bioenergetic-based bioaccumulation model. Mass balance results indicate that uptake of HCB by the gut from ingested solids was the single most important route, accounting for 63 to 84% of HCB tissue residues. The next largest route was uptake from interstitial water ventilated across the gills, which accounted for 11 to 12% of tissue residues. Uptake of HCB from overlying water was minimal. These results indicate that sediment-bound HCB is bioavailable to benthic deposit feeders such as Macoma and supports the contention that ingested sediment is an important uptake route for highly lipophilic pollutants.
Use of a flow-through in situ environmental chamber to study microbial adaptation processes in riverine sediments and periphyton
Authors: Shimp Robert J. , Schwab Burney S.
Published: March 2010

Adaptation of sediment-associated and periphytic microbial communities to the quaternary ammonium surfactant dodecyltrimethylammonium chloride (C12-TMAC) was assessed using an in situ environmental chamber. The chamber was placed on the bottom of the Little Miami River (Ohio) and consisted of six channels that were aligned so the river water flowed through them. Concentrated C12-TMAC was dosed to the channels to achieve nominal concentrations of 0 (control), 0.25 and 25 mg/L. Periodically, samples of sediment and periphyton were removed and the biodegradation of C12-TMAC was measured. Results demonstrated that the in situ system was a useful method for assessing the impact of chemicals on aquatic microbial communities. Adaptation to C12-TMAC occurred in both sedimentary and periphytic compartments within 5 to 10 d of exposure. Both biodegradation potential (Vmax) and first-order biodegradation rate constants (K1) increased 15- to 60-fold relative to activity in the control channel. Adaptation was accompanied by an increase in the most-probable number (MPN) of C12-TMAC degraders. However, the increase in MPN was not directly proportional to the increase in biodegradation activity. Results from this work were comparable to previous research using laboratory microcosms, indicating that such laboratory systems are comparatively accurate models of field-measured adaptation responses.
In situ mineralization of chlorinated phenols by pelagic bacteria in lakes of differing humic content
Authors: Tranvik Lars , Larsson Per , Okla Lennart , Regnell Olof
Published: March 2010

The microbial mineralization of phenol and three chlorinated phenols (3,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the water column of 23 pristine, oligotrophic lakes of different humic content was investigated. During short-term (∼2 d) in situ incubations of water samples amended with 14C-labeled phenolic compounds, the fraction of the added pollutant mineralized to 14CO2 was positively correlated with water color (an estimate of humic content) and the total organic carbon concentration of the water. The rate of mineralization per bacterial cell was not correlated with humic content, due to increased bacterial abundance with increasing humic content. Hence, the higher mineralization rate in humic lakes than in clear-water lakes was probably a result of higher bacterial abundance rather than being an effect of bacterial cells having a higher potential for the degradation of such compounds.
In situ and laboratory sediment toxicity testing with ceriodaphnia dubia
Authors: Sasson-Brickson Gemini , Burton G. Allen
Published: March 2010

Ecological assessments of sites containing hazardous wastes are improved by field testing. In situ exposures of Ceriodaphnia dubia were conducted in a stream impacted by several effluents, a combined sewer overflow and a creosote treatment operation. Sediments contained high levels of metals and polynuclear aromatic hydrocarbons. Fish and macroinvertebrate community indices were depressed. Ceriodaphnia dubia were placed in sediment exposure chambers in the stream for 48 h and also exposed to sediments that were simultaneously collected in the laboratory. Percent survival was generally higher in situ as compared to static laboratory exposures; however, overlying water toxicity was lower in laboratory assays. Average survival rates in elutriate fractions were slightly higher than interstitial or solid-phase exposures, and filtration reduced both elutriate and interstitial fraction toxicity. In situ sediment exposures proved to be sensitive indicators of both degraded and nondegraded stream conditions. Results show traditional sample collection and laboratory toxicity test methods may alter the water and sediment toxicity that occurs in situ. This highlights the importance of laboratory validation and in situ testing in aquatic safety assessments.
Degradation of aromatic compounds bound to humic acid by the combined action of sunlight and microorganisms
Authors: Amador José A. , Alexander Martin , Zika Rod G.
Published: March 2010

A study was conducted of the degradation of aniline-humic acid and phenol-humic acid complexes by sunlight and the subsequent mineralization by microorganisms. Irradiation of anilinehumic acid and phenol-humic acid complexes in sunlight resulted in a loss of UV light absorbance and the formation of low-molecular-weight products. Sunlight irradiation of the aniline-humic acid complexes had no effect on their subsequent mineralization. The rate and extent of mineralization of the phenol-humic acid complexes were enhanced by sunlight irradiation. The mineralization of phenol-humic acid complexes increased with integrated solar flux and was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts. The effects of solar irradiation on molecular-weight distribution of the complexes appear to be independent of the organic compound used to form the complex. The effects of irradiation on microbial mineralization of the complexes are different for different organic compounds.
Cytochrome P450E (P450IA) induction and inhibition in winter flounder by 3,3′,4,4′-tetrachlorobiphenyl: Comparison of response in fish from georges bank and narragansett bay
Authors: Monosson Emily , Stegeman John J.
Published: March 2010

Induction of liver microsomal cytochrome P450 by 3,3′,4,4′-tetrachlorobiphenyl (TCB) was evaluated in winter flounder from two different sites, one offshore (Georges Bank) and one coastal (Narrow River, Narraganseti, Rhode Island). Immunoblot analysis of liver microsomes with monoclonal antibody 1–12–3 to scup P450E (P450IA1) revealed P450IA protein content of 0.01 nmol/mg in Georges Bank fish that were not treated with TCB. By comparison, untreated Narrow River fish had an 80-fold greater content of immunodetected P450IA protein, indicating a strong environmental induction in these fish. In Georges Bank fish the total (spectrophotometrically measured) microsomal P450 content and the content of P450IA protein were induced progressively by intraperitoneal doses of TCB ranging from 0.1 to 10.0 mg/kg. Ethoxyresorufin-O-deethylase (EROD) specific activity (activity per mg protein) was also progressively induced, but the catalytic efficiency or turnover number (i.e., activity/nmol P450IA) was less in fish given the greater doses of TCB. In Narrow River fish TCB treatment resulted in no significant change (at P ≤ 0.05) in total microsomal P450 content or in P450IA protein content, although they tended to be less (total P450) or greater (P450IA) in fish given the greater doses. The EROD activity per mg protein was less in Narrow River fish given greater TCB doses than it was in control fish. EROD activities per nmol of P4501A protein in control Narrow River fish were less than those in any treatment group of Georges Bank fish and tended to diminish even further with TCB treatment. The results show that 3,3′,4,4′-TCB induces P450IA in winter flounder and that TCB acts in vivo to inhibit the activity of P450IA enzyme by mechanisms not yet known. The lower catalytic efficiency of P450IA enzyme in Narrow River fish than in Georges Bank fish indicates that P450IA inhibition, whether caused by TCB or some other agent, does occur in the environment. The data also indicate that prior condition, including existing environmental induction, can strongly influence the responses of P450IA protein to additional chlorobiphenyl exposure.
Desorption of chlorinated hydrocarbons from phytoplankton
Authors: Autenrieth Robin L. , Depinto Joseph V.
Published: March 2010

Studies were conducted to investigate the desorptive characteristics of hexachlorobenzene (HCB) and 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) sorbed to algal and sediment suspensions by using three approaches: batch equilibration, air purging and competitive exchange. In both short-term and extended batch desorptions, sorption partition coefficients were consistently greater than desorption partition coefficients. Air-purging removed virtually all of the sorbed HCBP within 2 h, exhibiting a two-component release pattern for all tested sorbents. In competitive sorption tests, HCB originally sorbed to suspended sediments was released to be taken up by algae. These studies indicate the importance of sorbent type in the magnitude and strength of sorption for two hydrophobic compounds.
The use of the physiological energetics of Gammarus pulex to assess toxicity: A study using artificial streams
Authors: Maltby Lorraine
Published: March 2010

A sublethal assay based on the energy budget of the freshwater amphipod Gammarus pulex has been developed. Gammarus “scope for growth” can be used both as a laboratory test and as an in situ bioassay. This paper provides a short review of the technique and investigates a way in which it may be simplified for field deployment. The usefulness of this modified technique for determining the toxicity of an organic compound and its relative sensitivity compared to other measures of toxicity was investigated by using an artificial stream system.
A phytoassay procedure using fluorescence induction
Authors: Caux P.-Y. , Blaise C. , Leblanc P. , Tache M.
Published: March 2010

A bioassay protocol has been developed to obtain the essential phytotoxicological data on toxicants influencing the electronic transport chain of the photosynthetic light reactions. The purpose of this study was to determine the principal physical factors affecting the photosynthetic fluorescence induction response (Kautsky effect) of algae grown in microplates. It was found that levels of relative fluorescence units (R.F.U.s) varied heterogeneously in a microplate whose 96 wells were inoculated with a culture of Selenastrum capricornutum at constant inoculum conditions for a period of 4 d. In order to account for this, the following parameters were analyzed: effect of evaporation processes, cell concentration, algal culture volume, probe distance, adjacent well proximity, plate well shape, and plate opaqueness. It was found that intraplate variation of R.F.U. levels occurred as a result of media evaporation from peripheral wells. R.F.U. levels were directly proportional to the culture cell concentration and to the culture cell volume but indirectly proportional to the culture distance from the light harvesting probe. R.F.U.s from black microplates gave a lower response but with less variation than those from translucent microplates.
Effects of environmental and experimental design factors on culturing and toxicity testing of Ceriodaphnia dubia
Authors: Cooney J.D. , Lenoble B.J. , Pollock T.L. , Smith G.J. , Degraeve G.M. , Moore E.L.
Published: March 2010

The U S. Environmental Protection Agency (EPA) has developed a 7-d toxicity test to evaluate effects of effluents on Ceriodaphnia dubia survival and reproduction. This study evaluated effects of laboratory culture and test procedures on Ceriodaphnia dubia survival and reproduction Parameters such as temperature, food concentration, beaker size, solution-renewal frequency, light quality, illumination, photoperiod, water type, and test organism age were evaluated to determine how these culture and test parameters affected individual culturing success and acceptability and reproducibility of toxicity test results. Test parameters proposed by the EPA were evaluated under controlled laboratory conditions by varying levels of individual environmental or experimental design parameters to determine an acceptable range of responses for survival and reproduction, both with and without a reference toxicant For those parameters not specified by the EPA (e.g, water hardness, light quality), commonly used ranges for those parameters were evaluated.

Results provided a decision matrix of acceptable ranges for individual environmental and experimental design parameters that were used to optimize the test parameters for conducting 7-d effluent tests with Ceriodaphnia dubia Overall, of the studied test parameters, renewal frequency and photopenod were the primary factors affecting culture and toxicity test success In this study, the EPA restriction on Ceriodaphnia dubia age at test initiation was not critical, as long as all organisms were <24 h old and randomly distributed among the test concentrations