bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradation of simple chemical mixtures in soil
Authors: Donnelly Kirby C. , Huebner Henry J. , Claxton Larry D. , Calvin James A. , Vos Gordon A. , Cizmas Leslie , He Ling-yu 
Published: October 2005

Abstract
Exogenous microorganisms often are used to enhance bioremediation. This study compared the capabilities of two exogenous microbial cultures and an indigenous population to detoxify a Weswood silt loam soil amended with a simple chemical mixture. The first three treatments were unamended soils inoculated with either indigenous microorganisms, Pseudomonas aeruginosa, or Phanerochaete sordida. Three additional treatments consisted of soil amended with benzo[a]pyrene, pentachlorophenol, and 2,4,6-trinitrotoluene, which were inoculated with either indigenous microorganisms, P. aeruginosa, or P. sordida. Samples were collected from the soils at several time points from 0 through 540 or 720 d, sequentially extracted with methylene chloride and methanol, and analyzed for genotoxicity (using the Salmonella/microsome assay) and chemical degradation. Although the indigenous microorganisms were effective for removal of benzo[a]pyrene, the Pseudomonas bacteria exhibited slightly greater removal rates for 2,4,6,-trinitrotoluene. The fungal cultures were significantly more effective at degrading pentachlorophenol. The day 540 extracts from all model chemical-amended treatments were genotoxic. In most cases, the day 540 extracts were more genotoxic than the day 0 extracts. The results suggest that, under appropriate conditions, enriched cultures of microorganisms may have an increased capacity to degrade individual chemicals. However, the products of degradation in some cases might be more genotoxic than the parent compounds.
Bacterial cell association and antimicrobial activity of a C60 water suspension
Authors: Lyon Delina Y. , Fortner John D. , Sayes Christie M. , Colvin Vicki L. , Hughes Joseph B. 
Published: October 2005

Abstract
Prior to the implementation of any new technology, possible environmental and health repercussions first must be researched. Fullerenes are to be produced soon on an industrial scale, with applications quickly following. To investigate the possible environmental impact of fullerenes, a C60-water suspension (nano-C60) was synthesized and then evaluated for cell-association and toxicity, using the bacteria Escherichia coli and Bacillus subtilis as indicator species. In a defined low-salts medium, nano-C60 associated with both the Gram-negative E. coli and the Gram-positive B. subtilis, albeit more strongly with the former. Nano-C60 also displayed antimicrobial properties against both E. coli and B. subtilis, with minimal inhibitory concentrations of 0.5 to 1 mg/L and 1.5 to 3.0 mg/L, respectively. Media with higher salt contents result in the nano-C60 particles aggregating and falling out of suspension; thus, higher salt solutions reduced or eliminated the antimicrobial properties of nano-C60.
Reductive transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, and methylenedinitramine with elemental iron
Authors: Oh Seok-Young , Cha Daniel K. , Kim Byung J. , Chiu Pei C. 
Published: October 2005

Abstract
Reductive (pre)treatment with elemental iron is a potentiallyuseful method for degrading nitramine explosives in water and soil. In the present study, we examined the kinetics, products, and mechanisms of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) degradation with elemental iron. Both RDX and HMX were transformed with iron to formaldehyde, NH +4, N2O, and soluble products. The yields of formaldehyde were relatively constant (71% ± 5%), whereas the yields of NH +4 and N2O varied, depending on the nitramine and the mechanism. The reactions most likely were controlled by a surface process rather than by external mass transfer. Methylenedinitramine (MDNA) was an intermediate of both RDX and HMX and was transformed quantitatively to formaldehyde with iron. However, product distributions and kinetic modeling results suggest that MDNA represented a minor reaction path and accounted for only 30% of the RDX reacted and 14% of the formaldehyde produced. Additional experiments showed that RDX reduction with elemental iron could be mediated by graphite and Fe2+ sorbed to magnetite, as demonstrated previously for nitroaromatics and nitrate esters. Methylenedinitramine was degraded primarily through reduction in the presence of elemental iron, because its hydrolysis was slow compared to its reactions with elemental iron and surface-bound Fe2+. Our results show that in a cast iron-water system, RDX may be transformed via multiple mechanisms involving different reaction paths and reaction sites.
Behavior of lead in a model microbial predator-prey system
Authors: Patton Leslie E. , Shuler Michael L. , Lion Leonard W. 
Published: October 2005

Abstract
Predation at the microbial level can affect the fate of toxic trace metals. Metals associated with bacterial prey can be released into the dissolved phase following digestion by a predator, and/or metals can remain in the predator and be transferred potentially to the next level of the food chain. Toxic metal ions in the aqueous phase also are expected to modify the growth and predation rate of a microbial predator. A model predator-prey system was developed to test the effects of Pb on cells and to help elucidate the fate of Pb in this type of interaction. Established methods that have been shown to be suitable for distinguishing dissolved, prey-bound, predator-bound, and ingested Pb were used to establish the pathway of Pb over time. Growth parameters were measured using batch reactors for the protozoan predator Tetrahymena thermophila and the bacterial prey Pseudomonas putida without Pb and at several concentrations of Pb. The effect of prey density on predation and Pb phase distribution also was investigated. Results demonstrate that some kinetic parameters related to prey consumption and growth of T. thermophila are altered by Pb. Upon addition of predator to prey cells in equilibrium with dissolved Pb, dissolved and prey-bound Pb become associated with the predator through ingestion and adsorption. Ingested Pb is excreted later as a bound metal associated with T. thermophila waste matter. A preliminary mathematical model was developed to describe predator-prey dynamics and their influence on the behavior and fate of Pb. Growth data were used to obtain model parameters, and model simulations for Pb fractionation are compared to experimental observations.
Exposure-related effects on Cd bioaccumulation explain toxicity of Cd-phenanthrene mixtures in Hyalella azteca
Authors: Gust Kurt A. , Fleeger John W. 
Published: October 2005

Abstract
Little is known regarding mixture effects of metals and polynuclear aromatic hydrocarbon (PAHs) under environmentally relevant exposure regimes. Standard U.S. Environmental Protection Agency (U.S. EPA) procedures were applied and extended to test effects of phenanthrene (Phen) on sediment-Cd uptake, aqueous-Cd uptake, and Cd-elimination kinetics in the amphipod Hyalella azteca. In sediment exposures, Phen increased the projected equilibrium-tissue concentration of Cd from 47.2 (36.2–58.3) to 221.1 μg/g ([117.8–324.3], 95% confidence intervals [CI] in parentheses). Although Cd bioaccumulation increased markedly in sediment exposures, dissolved Cd concentrations and physical-chemical parameters indicative of Cd bioavailability were unaffected by Phen. Further, in water-only exposures, Phen had no effect on Cd bioaccumulation or Cd-elimination kinetics. These results indicate that increased Cd bioaccumulation in Cd-Phen mixtures occurred via a sediment-mediated process and was likely a function of increased uptake associated with feeding (i.e., Pheninduced alterations in ingestion and/or digestive processes). Observed increases in H. azteca lethality when exposed to Cd-Phen mixtures in sediment, but not in water-only exposures, likely resulted from increased Cd bioaccumulation rate rather than a true toxicological synergism. Thus, apparent synergisms and antagonisms may result from exposure-mediated effects in sediment that are unrelated to toxicological interactions. Implications of these findings regarding sediment-quality assessment and suggestions for future studies are discussed.
Calcium/cadmium interactions at uptake surfaces in rainbow trout: Waterborne versus dietary routes of exposure
Authors: Franklin Natasha M. , Glover Chris N. , Nicol James A. , Wood Chris M. 
Published: October 2005

Abstract
Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to control, 3 μg/L waterborne Cd, or 500 mg/kg dietary Cd in combination with either a control (20 mg/g Ca2+ as CaCO3) or elevated (60 mg/g Ca2+) Ca2+ diet for 28 d. No mortality or growth effects were observed in response to either route of Cd exposure, although fish fed Ca2+-supplemented diets exhibited minor reductions in growth within the first few days of feeding. Waterborne and dietary Cd resulted in significant Cd accumulation in most tissues, with dietary uptake being far in excess of waterborne under the exposure conditions used. The order of Cd accumulation strongly reflected the exposure pathway, being gill and kidney &gt; liver &gt; gut &gt; carcass (waterborne Cd); gut &gt; kidney &gt; liver &gt; gill &gt; carcass &gt; bone (dietary Cd). On a whole-body basis, the net retention of Cd from the diet was &lt;1%, indicating that the gut wall forms an important protective barrier reducing Cd accumulation into internal tissues. Dietary Ca2+ supplementation reduced short-term whole-body uptake rates of waterborne Ca2+ and Cd by &gt;50% and resulted in much lower chronic accumulation of Cd (via the water and diet) in target tissues. Results suggest that Ca2+ and Cd share common pathway(s)/transport mechanism(s) in the gill and gut and that increased gastrointestinal Ca2+ uptake likely caused downregulation of branchial and gastrointestinal Ca2+ and therefore Cd uptake pathways. Because nutrient metals other than Ca2+ may also influence Cd (and other metal) uptake, new regulatory approaches to metal toxicity (e.g., biotic ligand model) require understanding of the influence of dietary status on metal accumulation.
Co-amendment with halogenated compounds enhances anaerobic microbial dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin and 1,2,3,4-tetrachlorodibenzofuran in estuarine sediments
Authors: Ahn Young-Beom , Häggblom Max M. , Fennell Donna E. 
Published: October 2005

Abstract
Halogenated coamendments enhanced dechlorination of 31 μM of spiked 1,2,3,4-tetrachlorodibenzo-p-dioxin (TeCDD) and 49 μM of spiked 1,2,3,4-tetrachlorodibenzofuran (TeCDF) in sediments from San Diego Bay (CA, USA) and Tuckerton (NJ, USA). Dechlorination of 1,2,3,4-TeCDD occurred to a greater extent under methanogenic than under sulfate-reducing conditions. The most effective stimulation of 1,2,3,4-TeCDD dechlorination occurred with coamendment of 25 μM of 1,2,3,4-tetrachlorobenzene (TeCB), 2,3,4,5-tetrachloroanisole (TeCA), 2,3,4,5-tetrachlorophenol, or 2′,3′,4′-trichloroacetophenone plus 500 μM lactate and 500 μM propionate as electron donors. The 1,2,3,4-TeCDD dechlorination was evident after three months and sequentially produced mainly 1,2,4-trichlorodibenzo-p-dioxin, 1,3-dichlorodibenzo-p-dioxin, and 2-monochlorodibenzo-p-dioxin (MCDD). Monobromo-phenols (2-bromo-, 3-bromo-, and 4-bromophenol), monochlorophenols (2-chloro-, 3-chloro-, and 4-chlorophenol), 2,3,5,6-tetra-chlorobenzoate, or electron donors alone stimulated less 1,2,3,4-TeCDD dechlorination, with activity apparent only after six months. The 1,2,3,4-TeCDD dechlorination produced 50 mol % 2-MCDD after six months in sediments from the more contaminated Graving Dock and Paleta Creek sites in San Diego Bay. The 1,2,3,4-TeCDD dechlorination by sediments from the less contaminated Shelter Island site in San Diego Bay and in pristine Tuckerton sediments did not produce 2-MCDD. Dechlorination of 1,2,3,4-TeCDF to tri- and dichlorinated daughter products was significantly enhanced by TeCB and TeCA. These results suggest that halogenated aromatic compounds with structural similarity to 1,2,3,4-TeCDD/F stimulate bacteria with the ability to dechlorinate chlorinated dibenzo-p-dioxin and furans.
Toxic effect of biosurfactant addition on the biodegradation of phenanthrene
Authors: Shin Kyung-Hee , Ahn Yeonghee , Kim Kyoung-Woong 
Published: October 2005

Abstract
The effect of the biosurfactant rhamnolipid on phenanthrene biodegradation and cell growth of phenanthrene degraders was investigated. To compare the effect of rhamnolipid addition, two bacterial strains, 3Y and 4–3, which were isolated from a diesel-contaminated site in Korea, were selected. Without the biosurfactant, large amounts of phenanthrene were degraded with both strains at neutral pH, with higher rates of phenanthrene degradation when the cell growth was higher. Upon the addition of 240 mg/L rhamnolipid, the phenanthrene degradation and optical density were reduced, with this inhibitory effect similar for both 3Y and 4–3. To explain this inhibition, the cell growths of both strains were monitored with various concentrations of rhamnolipid, which showed significant toxic effects toward strain 3Y, but was nontoxic toward 4–3. Combining the inhibitory and toxicity results with regard to the biodegradation, different mechanisms can be suggested for each strain. In the biodegradation experiments, the toxicity of rhamnolipid itself mainly was responsible for the inhibitory effect in the case of 3Y, whereas the toxicity of solubilized phenanthrene or the increased toxicity of rhamnolipid in the presence of solubilized phenanthrene could have resulted in the inhibitory effect in the case of 4–3. This study demonstrated that the effectiveness of biosurfactant-enhanced biodegradation can be significantly different depending on the strain, and the toxicity of the biosurfactant should be considered as an important factor.
Multigenerational acclimation of Daphnia magna to mercury: Relationships between biokinetics and toxicity
Authors: Tsui Martin T. K. , Wang Wen-Xiong 
Published: October 2005

Abstract
We examined the effects of multigenerational exposure of mercury (Hg) on Hg toxicity and biokinetics in a population of Daphnia magna. After chronic Hg exposure at 3.8 μg Hg/L, the first generation (F0) adults had an elevated 24-h median lethal concentration (LC50) of Hg (76 μg/L) when compared to the control adults (56 μg/L). The dissolved influx rate of Hg was depressed significantly in the Hg-treated adults, which was accompanied by a reduced ingestion rate and enhanced induction of metallothionein-like proteins (MTLP). The second-generation (F1) juveniles originating from the control and exposed lines had no major differences in these parameters (except the dietary assimilation efficiency). Recovery from Hg stress enhanced the vulnerability of F1 adults to Hg toxicity, with a reduced 48-h LC50 (44 μg/L) and a decreased concentration of MTLP (80% of control). Nevertheless, Hgtreated F1 adults had similar tolerance (in terms of LC50s) as the control line, indicating that D. magna acclimated to Hg stress after the first generation of exposure. No major difference occurred in the Hg biokinetics and toxicity among different groups of F2 daphnids. However, the F2 neonates produced by the Hg-treated F1 adults had much higher 48-h LC50 (149 μg/L) and MTLP concentration (148% of control) when there was continuous Hg exposure after birth. We concluded that acclimation to Hg stress occurred quickly in D. magna, though animals recovering from Hg stress were more vulnerable to Hg toxicity. Both ingestion rate and MTLP may not be good biomarkers of Hg stress in the field, because acclimation can be achieved through multigenerational exposure to elevated Hg concentrations.
In vivo bioassay-guided fractionation of marine sediment extracts from the Southern California Bight, USA, for estrogenic activity
Authors: Schlenk Daniel , Sapozhnikova Yelena , Irwin Mary Ann , Xie Lingtian , Hwang Wendy , Reddy Sharanya , Brownawell Bruce J. , Armstrong Jeff , Kelly Mike , Montagne David E. , Kolodziej Edward P. , Sedlak David , Snyder Shane 
Published: October 2005

Abstract
The exposure and uptake of environmental estrogenic compounds have been reported in previouss studies of demersal flatfish species in the central Southern California Bight (SCB), USA. The objective of this study was to evaluate the estrogenic or feminizing activity of marine sediments from the SCB by using in vivo vitellogenin (VTG) assays in male or juvenile fish. In 2003, sediments were collected near wastewater outfalls serving the counties of Los Angeles (LACSD) and Orange (OCSD), and the city of San Diego (SD), California, USA. Cultured male California halibut (CH; Paralichthys californicus) were either directly exposed to sediments for 7 d or treated with two intraperitoneal injections of sediment extract over 7 d. The 17β-estradiol (E2) equivalent values ranged from 1 to 90 μg/kg with LACSD &gt; SD &gt; OCSD. Measurable concentrations of E2 were observed in all sediment extracts and ranged from 0.16 to 0.45 ng/g. Estrone (E1) was only observed in sediments near the LACSD outfall (0.6 ng/g). Alkylphenols and alkylphenol ethoxylates were observed in all sediment samples, but were highest near the OCSD outfall, where concentrations of nonylphenol were 3,200 ng/g. Fractionation studies of the LACSD sediment extract collected in 2004 failed to demonstrate relationships between VTG expression and 62 analytes, including E2, which was observed in the whole extract (2.9 ng/g). Oxybenzone (1.6 ng/g) was identified in bioactive fractions as well as unknown compounds of relatively high polarity. These results indicate that estrogen receptor-based assays may underestimate environmental estrogenic activity and estrogenic compounds other than classic natural and xenoestrogens may contribute to estrogenic activity of sediments from the SCB.
Biodegradation during contaminant transport in porous media: 7. Impact of multiple-degrader community dynamics
Authors: Wang Jiann-Ming , Patterson Brandolyn , Bodour Adria , Maier Raina M. , Brusseau Mark L. 
Published: October 2005

Abstract
The biodegradation and transport of phenanthrene in porous media containing multiple populations of phenanthrene degraders is examined with a series of miscible-displacement experiments. A long-term experiment was conducted with a soil containing an indigenous microbial community comprised of 25 identified phenanthrene-degrading isolates. The rate and magnitude of phenanthrene biodegradation oscillated throughout the six-month experiment. This behavior, at least in part, is attributed to multiple-population dynamics associated with the indigenous community of phenanthrene degraders, the composition of which changed during the experiment. This hypothesis is supported by the results of experiments conducted using sterilized porous media that were inoculated with selected isolates obtained from the indigenous soil community. The results of experiments conducted with sterilized soil inoculated with isolate A exhibited an initial extended period of steady phenanthrene effluent concentrations, followed by a uniform decline. The results of experiments conducted using sterilized sand for single-isolate systems with one of three selected isolates and for systems of two-isolate combinations, indicate the existence of apparent synergistic and antagonistic interactions among the isolates. For example, phenanthrene biodegradation was relatively extensive and occurred without a lag phase for isolate A alone. However, biodegradation was constrained when isolate A and B were combined, indicating an antagonistic interaction. Conversely, whereas extensive lag phases were exhibited by both isolates B and C for the single-isolate experiments, there was minimal lag when isolates B and C were combined, indicating a synergistic interaction.
Uptake of nonylphenol and nonylphenol ethoxylates by crested wheatgrass
Authors: Doucette William J. , Wheeler Bryan R. , Chard Julie K. , Bugbee Bruce , Naylor Carter G. , Carbone John P. , Sims Ronald C. 
Published: October 2005

Abstract
Nonylphenol (NP) and other hydrophobic biodegradation intermediates of nonylphenol ethoxylate (NPE) surfactants have been identified in wastewater treatment biosolids. These biosolids often are land applied, but little is known regarding the potential uptake of biosolid-derived contaminants by plants. Hydroponic experiments, 11 to 14 weeks in duration, were conducted to examine the uptake and translocation of 14C and unlabeled NP, nonylphenol tetraethoxylate (NPE4), and nonylphenol nonylethoxylate (NPE9) by crested wheatgrass (Agropyron cristatum). Phenol also was evaluated for comparison. Plant tissue was analyzed for 14C and for the parent compounds. Volatilization from the hydroponic system and rhizosphere mineralization also were quantified. At the conclusion of the study, most of the plant-associated 14C was found in the roots (NP = 98%, NPE4 = 92%, and NPE9 = 81%). Concentrations of 14C in the foliar tissue ranged from 0.002 to 0.045 mg—equivalent per kg (dry wt), but no parent compounds were detected, implying that the 14C was unextractable or in the form of metabolites. Transpiration stream concentration factors for NP, NPE4, and NPE9, calculated assuming the 14C was parent compound, were 0.012, 0.032, and 0.066, respectively. Little mineralization was observed for NP, NPE4, and NPE9 in the hydroponic system; however, for phenol, 16 to 30% of the added 14C was mineralized.
Distinctive sorption mechanisms of soil organic matter and mineral components as elucidated by organic vapor uptake kinetics
Authors: Shih Yang-Hsin , Wu Shian-Chee 
Published: October 2005

Abstract
Sorption kinetics and capacities of volatile organic compounds (VOCs) affect the remediation and fate of these pollutants in soils. The soil organic-mineral compositional heterogeneity complicates the transport and fate of VOCs in soils. The sorption kinetics of toluene vapor with two common soil components, kaolinite and humic acid, shows two distinct sorption patterns. Results with kaolinite are characteristic of surface adsorption, whereas results with humic acid are characteristic of solvation and partition effects. On soils, the kinetics of toluene vapor sorption show a two-stage sorption phenomenon. The first stage is reflective of surface adsorption (1–4 h to completion) and the second stage of much slower partitioning into soil organic matter, which was preceded by a lag phase (∼4 h) and took as long as 15 h for completion. The relative contributions of these two stages to soil uptake are quantifiable by two independent parameters, the soil organic fraction and the surface area. A better understanding of the effect of soil compositional heterogeneity on sorption kinetics and capacities facilitates our understanding of the prediction for the fate of organic contaminants in the environment.