bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of primary productivity and vertical mixing on pcb dynamics in planktonic model ecosystems
Authors: Millard E.S. , Minns C.K. , Charlton C.C. , Halfon E. 
Published: March 2010

Abstract
Radiolabeled polychlorinated biphenyls (PCBs) [14C]-Aroclor 1242 were added to large planktonic model ecosystems. Two experiments were conducted to determine the influence of turbulent mixing and primary productivity on fate and transport of PCBs. High productivity increased the proportion of added PCBs that were adsorbed to particulate matter and sedimented. Retention of added PCBs within the model ecosystems increased the recovery in a budget of added PCBs. Volatilization losses increased at the high-mixing and low-productivity level. Highest recovery was with a high productivity-low mixing treatment. A third experiment was conducted in which PCBs adsorbed to clay were added to the hypolimnion of one model ecosystem. Results confirmed that PCBs unaccounted for in a budget of PCBs added to the epilimnion in the same manner were lost due to volatilization. A linear-fate model was developed to describe trends in PCB concentrations as well as fate of the added PCBs. Model parameters and predicted fate of added PCBs agreed closely with observed results. The model indicated that an unmeasured pool of particulate PCBs that were probably adsorbed to colloids and fine particulates was operationally measured with the soluble fraction.
Evaluation of five biocarriers as supports for immobilized bacteria: Comparative performance during high chemical loading, acid shocking, drying and heat shocking
Authors: Heitkamp Michael A. , Adams William J. , Camel Valérie 
Published: March 2010

Abstract
Immobilized bacteria technology (IBT) utilizes inert biocarriers to support high concentrations of chemical-degrading bacteria in reactors designed to provide optimal conditions for microbial activity. This study evaluated IBT performance in packed bed reactors (PBRs) using a porous inorganic biocarrier (diatomaceous earth), nonporous biocarriers (glass beads), and organic biocarriers having carbon adsorption properties (granular activated carbon) with different porosity. Each reactor was challenged with high chemical loading, acid, dryness, and heat shock conditions. Benchtop PBRs inoculated with ap-nitrophenol- (PNP)- degrading Pseudomonas sp. and fed a synthetic waste containing 100 to 1,300 mg/L of PNP showed removal of PNP from effluents within 24 h of start-up. Chemical loading studies showed maximum PNP removal rates of 6.45 to 7.35 kg/m3/d for bacteria in PBRs containing diatomaceous earth beads, glass beads, and activated coconut carbon. A lower PNP removal rate of 1.47 kg/m3/d was determined for the activated anthracite carbon, and this PBR responded more slowly to increases in chemical loading. The PBR containing bacteria immobilized on activated coconut carbon showed exceptional tolerance to acid shocking, drying, and heat shocking by maintaining PNP removal rates &gt; 85% throughout the entire study. The other biocarriers showed nearly complete loss of PNP degradation during the perturbations (except for drying), but all recovered high rates of PNP degradation (&gt; 98% removal) within 48 h after an acid shock at pH 2, within 8 d after an acid shock at pH 1.0, within 24 h after drying for 72 h, and within 48 h of heat shocking. The resiliency and high chemical removal efficiency demonstrated by immobilized bacteria in this study support the concept of using IBT for the biotreatment of industrial wastes.
Mercury and selenium in harbor porpoise (Phocoena phocoena) in norwegian waters
Authors: Teigen Sverre Weberg , Skaare Janneche Utne , Sand Gunhild , Bjørge Arne , Degre Eva 
Published: March 2010

Abstract
Concentrations of mercury and selenium have been determined in liver and kidney of 92 harbor porpoises (Phocoena phocoena) caught along the Norwegian coast. The hepatic and renal mercury concentrations ranged from 0.26 to 9.9 and 0.15 to 3.5 μg g−1, respectively, whereas the corresponding selenium concentrations ranged from 0.74 to 14.2 and 0.60 to 8.6 μg g−1, respectively. No significant differences in mean concentrations of mercury and selenium were found between females and males within the same age classes. However, the concentrations were positively correlated with age. The present results revealed a decreasing mercury concentration gradient from south to north along the Norwegian coast. In all age classes, a significant, positive correlation between the concentrations of mercury and selenium was found in both liver and kidney, the molar mercury-to-selenium ratio being 0.9660 and 0.2151, respectively. Implications of these findings for the biochemical and toxicological behavior of mercury and selenium in the harbor porpoise are considered.
Biotransformation of chlorinated aliphatic solvents in the presence of aromatic compounds under methanogenic conditions
Authors: Liang Li-Nuo , Grbić-Galić Dunja 
Published: March 2010

Abstract
Transformation of carbon tetrachloride (CT) and tetrachloroethylene (PCE) was studied under methanogenic conditions, in the presence or absence of toluene, ethylbenzene, phenol, and benzoate. Microbial inocula for the experiments were derived from three groundwater aquifers contaminated by jet fuel or creosote. CT and PCE were reductively dechlorinated in all the examined cases (CT to chloroform [CF]; PCE to trichloroethylene [TCE], trans-l,2-dichloroethylene [DCE], and vinyl chloride [VC]). In the aquifer microcosms, the electron donors used for the reductive transformations were most likely the unidentified organic compounds present on aquifer solids, or storage materials in microorganisms. Alternatively, molecular hydrogen from the anaerobic incubator atmosphere could have been used. The addition of benzoate caused a decrease in rates of dechlorination if benzoate was transformed. Phenol and ethylbenzene were not degraded and did not influence the transformation of CT or PCE. Toluene, in most of the studied cases, had no influence on reductive dechlorination of either CT or PCE. Only in microcosms derived from a JP-4 jet fuel-contaminated aquifer did the anaerobic degradation of toluene occur simultaneously with reductive dechlorination of PCE, suggesting that toluene might possibly have been used as an electron donor for reductive transformation of chlorinated solvents.
Defining and assessing ecological integrity: Beyond water quality
Authors: Karr James R. 
Published: March 2010

Abstract
Emphasis in environmental protection is shifting from primary attention to human health to a more balanced consideration of human and ecological health. This shift provides opportunities and challenges to the scientific community. For example, success depends on development of operational definitions of ecological health and programs to measure that health. Ecological health is inextricably tied to concepts such as biological diversity and biological integrity. Water chemistry and toxicity testing have dominated water-quality programs for decades. Success in protecting the ecological health of water resources depends on our ability to supplement those methods with ecologically robust approaches. Existing definitions and approaches for measuring the quality of water resources provide a template to guide development of procedures to assess ecological health. Critical components of successful monitoring programs should include evaluations relative to regional expectations, use multimetric indexes that reflect the multivariate nature of biological systems, and include index components (metrics) that evaluate conditions from individual, population, assemblage, and landscape perspectives.
Concentrations and deposition fluxes of polynuclear aromatic hydrocarbons and heavy metals in the dated sediments of a rural english lake
Authors: Sanders Gordon , Jones Kevin C. , Hamilton-Taylor John , Dorr Helmut 
Published: March 2010

Abstract
Deposition fluxes have been estimated from concentrations of 12 polynuclear aromatic hydrocarbons (PAHs) and six heavy metals measured in sediment cores from Esthwaite Water, a rural English lake. Atmospheric deposition is a major source of PAHs and heavy metals (Cd, Cu, Pb, and Zn) to the lake, so trends in the core may indicate the long-term record of changes in the atmospheric loading of these pollutants. The cores were dated radiometrically and pollutant trends studied since about 1820. PAH fluxes began to increase from stable background levels around the turn of the century (4.1 μg ΣPAH per gram dry weight, 287 ng ΣPAH per centimeter squared per year), rising to maximum inputs between 1950 and 1970 (42.0 μg/g, 2,954 ng/cm2 per year). The deposition flux of PAHs has decreased steadily since then and is now less than half the maximum (18.0 μg/g, 1,238 ng/cm2 per year). In recent sediments (1900-1970), the relative proportions of individual PAHs making up the ΣPAH burden have remained virtually unchanged, with fluoranthene, pyrene, and benzo[ghi]perylene the most abundant compounds. However, perylene, a biogenically produced PAH, dominates the mixture in the sediments older than 1890. Cadmium, Cu, Ni, Pb, and Zn concentrations in the Esthwaite sediments broadly follow the same temporal trends as the PAHs, with varying peak inputs between 1925 and 1975. Concentrations in the modern (surface) sediments are now lower than in recent decades, with ΣPAH, Cd, and Pb showing the greatest reduction. However, fluxes of these contaminants to surface sediments are still greater than those deposited before 1840.
LAS removal and biodegradation in a wastewater treatment plant
Authors: Cavalli L. , Gellera A. , Landone A. 
Published: March 2010

Abstract
Linear alkylbenzene sulfonate (LAS) biodegrades easily and loses its tensioactive properties quickly through a primary biodegradation process, as many works of literature testify. Many studies have been carried out in laboratories or in pilot plants, whereas few have been undertaken in a wastewater treatment plant (WWTP). In Italy, unlike in other countries, no detailed investigation has been made so far to establish LAS biodegradation in real WWTP conditions. EniChem Augusta (EA) and Consorzio Po-Sangone (CPS) have worked together for over two years on this problem, taking into consideration the large (flow rate: approximately 400 × 103 m3/d) and central active sludge WWTP of the metropolitan area of Torino, north of Italy. Specific LAS data have been obtained, using established HPLC techniques, in influent and effluent streams, in the dissolved (waters) and adsorbed (suspended solids and sludges) phases, to reach a complete mass balance. LAS removal &gt;99% and LAS biodegradation of approximately 85% have been observed. Attention also has been given to LAS intermediates of biodegradation, namely the sulfophenyl carboxylates (SPC), using HPLC and GC-MS techniques, the latter after derivatization. The SPCs have been found present only in the waters and not in the adsorbed phases (SS and sludges).
Behavior and fate of surfactants in soil
Authors: Kuhnt Gerald 
Published: March 2010

Abstract
Although a growing number of investigations have dealt with selected aspects of the behavior of surfactants in soil and their effects on various soil properties, systematic approaches like those applied to pesticides or heavy metals are still rare. Considering that soil is exposed to a considerable quantity of surfactants, it would appear necessary to do more intensified research in this field. Based on a comprehensive review of the literature, the author briefly outlines the behavior and fate of surfactants in soil and presents a synopsis from the viewpoint of a pedologist. Even at low concentrations, surfactants seem to alter soil physics, soil chemistry, and soil biology significantly, whereby sorption processes play a dominant role. The report tries to integrate the most important research results in this field and to interpret them against the background of the complex structure of the soil system.
Persistence and degradation of [14C]atrazine and [14C]deisopropylatrazine as affected by soil depth and moisture conditions
Authors: Kruger Ellen L. , Somasundaram L. , Coats Joel R. , Kanwar Ramesh S. 
Published: March 2010

Abstract
The fate of atrazine and one of its degradation products deisopropylatrazine has been investigated using radiotracers under laboratory conditions. The metabolic route and rate were investigated under saturated and unsaturated conditions, with samples of soil taken from four depths down to 120 cm. The major degradation products identified from [14C]atrazine and [14C]deisopro-pylatrazine treatments were deethylatrazine and didealkylatrazine, respectively. The detected minor degradation products were hydroxyatrazine, deethylhydroxyatrazine, and deisopropylhydroxyatra-zine. Under unsaturated conditions atrazine and deisopropylatrazine were least persistent in the top 30 cm, and their persistence increased with increase in depth. The half-life of atrazine under unsaturated conditions increased with depth and ranged from 41 to 231 d for the studied depths, whereas the half-life of deisopropylatrazine ranged from 32 to 173 d. Deisopropylatrazine was more susceptible to mineralization than atrazine, and the amount of mineralization decreased with increase in depth. Bound residues were formed to a greater extent in surface soils. Under saturated conditions at the 90- to 120-cm depth, the half-life of atrazine was 87 d. Deisopropylatrazine was less persistent in saturated soil than in unsaturated soil at the 90- to 120-cm depth, with a half-life of 58 and 173 d, respectively. The increased degradability of deisopropylatrazine as compared with atrazine and the decreased persistence of deisopropylatrazine under saturated soil conditions provides a logical explanation for its relatively low concentrations in ground water as compared with atrazine.
Sources and impacts of irrigation drainwater contaminants in arid wetlands
Authors: Lemly A. Dennis , Finger Susan E. , Nelson Marcia K. 
Published: March 2010

Abstract
Arid wetlands are being contaminated by subsurface agricultural irrigation drainage throughout the western United States. Historic freshwater inflows have been diverted for agricultural and municipal use, and remaining freshwater supplies are not sufficient to maintain the integrity of these important natural areas once they are degraded by irrigation drainwater. Waterfowl populations are threatened in the Pacific and Central Flyways; migratory birds have been poisoned by drainwater contaminants on at least six national wildlife refuges. Subsurface irrigation drainage is the most widespread and biologically important source of contaminants to wetlands in arid regions of the country. The case history of poisoning at Kesterson National Wildlife Refuge in California and studies at other locations by the U.S. Department of the Interior provide detailed information on the toxicity of drainwater contaminants to fish and wildlife. Biogeochemical conditions favorable for the production of toxic drainage are found throughout the western states. Two actions seem necessary to prevent further drainage-related degradation of arid wetlands. First is a reduction in the amount of contaminants reaching these wetlands, possibly involving regulatory intervention through the National Pollutant Discharge Elimination System permit process. Second, a better balance must be achieved in the way fresh water is allocated between agriculture and wildlife. Federally subsidized water has supported agriculture at the expense of wetlands for nearly 100 years in the western United States. This trend must be reversed if arid wetlands and their fish and wildlife populations are to survive.
Salinity and temperature effects on chronic toxicity of 2,4-dinitrophenol and 4-nitrophenol to sheepshead minnows (Cyprinodon variegatus)
Authors: Linton Tyler Keith , Mayer Foster L. , Simon Tasha L. , Malone Janice A. , Marking Leif L. 
Published: March 2010

Abstract
Toxicity tests (28-d early-life-stage) were conducted to determine the effects of nine combinations of salinity (15, 20, 25 ppt) and temperature (22, 27, 32°C) on the toxicity of 2,4-dinitrophenol (2,4-DNP) and 4-nitrophenol (4-NP) to sheepshead minnows (Cyprinodon variegatus). The highest tested concentration having no observed effect (NOEC) on mortality and growth was derived weekly. The NOECs at test termination indicated that the survival and growth of fish exposed to 2,4-dinitrophenol were not significantly affected by salinity, temperature, or the salinity temperature interaction. However, 28-d NOECs of fish surviving from 4-nitrophenol exposures were significantly affected by temperature, but the highest value exceeded the lowest by only a factor of two. The overall data suggest that variations of salinity and temperature do not change the NOEC; only the exposure time required to attain the same NOEC is altered.
The toxicokinetic behavior of chlorobenzenes in earthworm (Eisenia andrei) experiments in soil
Authors: Belfroid Angélique , Sikkenk Marieke , Seinen Willem , Hermens Joop , van Gestel Kees 
Published: March 2010

Abstract
The toxicokinetic behavior of some chlorobenzenes in earthworms (Eisenia andrei) kept in soil was studied. To determine elimination kinetics, worms were exposed to chlorobenzenes for 7 d, followed by a depuration period of 15 or 35 d. Elimination of chlorobenzenes by earthworms kept in soil was best fitted using a bi-exponential elimination curve. The half-life belonging to the slow phase was in good agreement with measured elimination half-lives for the same compounds by earthworms kept in water. Accumulation of chlorobenzenes in earthworms was studied by exposure over 50 d. Equilibrium was rapidly achieved within 7 d. BAFs based on the concentration in soil and on the concentration in the interstitial water were calculated. BAFs of 1,2,3,4-tetrachlorobenzene and pentachlorobenzene in earthworms kept in soil and BCFs in earthworms kept in water were comparable, demonstrating that uptake proceeds mainly via the interstitial water. For hexachlorobenzene, the BAF was much larger than the BCF, which suggests that intestinal uptake for this compound is an important complementary route.
Chemical fate and transport in a domestic septic system: Unsaturated and saturated zone geochemistry
Authors: Wilhelm Sheryl R. , Schiff Sherry L. , Robertson William D 
Published: March 2010

Abstract
Monitoring the septic system at a single family home provides quantitative information on geochemical evolution of septic tank effluent along its travel path In both the unsaturated and saturated (groundwater) zones, microbiological and chemical reactions occur that bring the effluent closer to equilibrium with the subsurface conditions In the unsaturated zone, 90% of the DOC is removed from the effluent, mostly by aerobic oxidation, and NH+4 in the effluent is almost completely ox ldized to NO−3 As these reactions occur in the tile field, the oxygen content of the soil gas is partially depleted Calcite dissolution from the soils in the unsaturated zone buffers the acidity of the oxidation reactions and increases Ca2+ concentrations In the saturated zone, organic carbon oxidation in the effluent plume apparently decreases dissolved oxygen concentrations to &lt;10 mg/L Potassium is retarded relative to other cations, and dissolved PO43 from the effluent is detectable in the ground water directly beneath the tile field but appears to be advancing very slowly, if at all, within the plume In addition NO3− concentrations remain above drinking-water standards (10 mg/L NO3 N) in the groundwater plume
Freshwater benthic algal population and community changes due to acidity and aluminum-acid mixtures in artificial streams
Authors: Genter Robert B. , Amyot Daniel J. 
Published: March 2010

Abstract
Communities of freshwater benthic algae were exposed to water acidified daily to pH 4.8 alone and in mixtures with 50, 100, or 500 μg L−1 Al. Daily acidification to nominal pH 4.8 in acidified treatments exposed algae to a range of pHs that led to a variety of Al species of different toxicity. Calcium concentrations in stream water were higher in acidified and Al treatments on day 1, and dissolved Al in stream water was higher in the highest Al treatment on days 1, 7, and 28; otherwise acid and Al treatments did not significantly alter Al and Ca in the exposure water. Calcium bioaccumulation by periphyton was lower in acidified and Al treatments on all sampling days. Concentrations of Mg in water and periphyton did not differ between treatments. The artificial stream system generated alkalinity to buffer acidified water; the amount of generated alkalinity returned to approximately the same levels for the first week, but the amount of alkalinity generated during the second week appeared to decline, and acid-only and acid-Al mixtures diverged in their ability to generate alkalinity during the third and fourth weeks. Aluminum in acidified water inhibited abundance of diatoms and green and blue-green algae more than the effects of acid stress alone. The green filamentous alga Mougeotia showed a slight (but not statistically significant) increase in abundance in the acid-only treatment. The middle-Al treatment (nominally 100 μg L−1 Al and acid) generated more alkalinity and had higher abundance of some algal taxa on days 14 and 28, even though measured Al concentrations in water and periphyton fell between low- and high-Al-treatment levels. Community-level tests, combining a taxonomic analysis of algal population abundance with chemical analysis of water and bioaccumulation, provide valuable insight to assess anthropogenic stress.
Model for uptake of xenobiotics into plants: Validation with bromacil experiments
Authors: Trapp Stefan , Matthies Michael , McFarlane Craig 
Published: March 2010

Abstract
This paper documents a conceptual model for the uptake of anthropogenic organic chemicals into plants. The model describes the dynamic uptake from soil, solution, or atmosphere, and the metabolism and accumulation of xenobiotic chemicals in roots, stems, leaves, and fruits. The goal was to develop an easy and rapid tool that would be numerically stable and require only a few well-known input data. The model is applicable to different plant species and most (nondissociating) organic chemicals. Processes considered are (a) diffusive exchange, soil/roots, and air/leaves; (b) mass flows in xylem and phloem; and (c) metabolism. The model is tested with laboratory studies on the uptake of the herbicide bromacil under various controlled conditions. No adjustments to the parameter values were required for successful simulations.
Biodehalogenation, reductive dehalogenation by Methanobacterium Thermoautotrophicum. Comparison with nickel(I)octaethylisobacteriochlorin anion. An F-430 model
Authors: Castro C.E. , Helvenston M.C. , Belser N.O. 
Published: March 2010

Abstract
The reductive dehalogenation of 1,1,2-tnchloroethane, chloroform, fluorotrichloromethane, carbon tetrachloride, 1,1,1-tnchloroethane, and ethylene dichlonde by Methanobactenum thermoautotrophicum occurs slowly at 60°C in the listed order. Vinyl chloride and chloroacetic acid are inert. The average t1/2 for nearly all substrates is approximately 100 h and varies by a factor of approximately two. In contrast, an active site model for factor F-430, Ni1octaethyhsobactenochlorin, brings about the same transformations with astonishing speed and vast differences in specific rates It is suggested that despite the enormous reducing capacity of this anaerobe, the overall reduction process is limited by permeation factors.