bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slowly and very slowly desorbing organic compounds in sediments exhibit langmuir-type sorption
Authors: Cornelissen Gerard , Rigterink Henk , van Noort Paul C M , Govers Harrie A J 
Published: March 2010

AbstractDesorption kinetics were determined for 1 2,4-trichlorobenzene (TCB), 13-dichlorobenzene (DCB), and trichloroeth-ylene (TCE) in a sediment at various concentrations. The desorption data were interpreted with a (nonmechanistic) first-order three-compartment model. In this way, separate sorption isotherms could be constructed for rapidly, slowly, and very slowly desorbing sorbate, respectively. Slowly desorbing (rate constant k ∼10−3/h) and very slowly desorbing (k = 10−4 to 10−5/h) sorbate exhibited nonlinear Langmuir-type sorption, with capacities on the order of 4.6 to 19 and 0.54 to 1.5 mmol/kg organic carbon (OC) and affinity constants of 0.18 to 41 and 32 to 272 L/mmol, respectively. The affinity constants increased with increasing sorbate hydrophobicity. Rapidly desorbing (k = 10−1/h) sorbate showed linear sorption isotherms, with log Koc (octanol–water partition coefficients) of 1.59 ± 0.12 (TCE), 2.03 ± 0.13 (DCB), and 3.13 ± 0.03 (TCB), respectively. These results confirm the hypothesis that desorption is rapid from linearly sorbing organic matter, whereas it is slow and very slow from nonlinearly sorbing sites. Furthermore, the results also demonstrate the applicability of the desorption kinetic method in terms of experimentally separating an overall Freundlich-like isotherm in linear and nonlinear isotherms.
Riverine endosulfan concentrations in the Namoi River, Australia: Link to cotton field runoff and macroinvertebrate population densities
Authors: Leonard Alex W , Hyne Ross V , Lim Richard P , Pablo Fleur , Van den Brink Paul J 
Published: March 2010

Abstract
Population densities of six dominant macroinvertebrate taxa (mayfly nymphs Jappa kutera, Atalophlebia sp., Tasma-nocoenis sp., Baetis sp. and the caddisfly larvae Cheumatopsyche sp. and Ecnomus sp.) were negatively correlated to total endosulfan concentrations in the Namoi River (New South Wales, Australia) in the 1995/96 and 1997/98 cotton growing seasons (November-March). Total endosulfan concentrations measured in solvent-filled polyethylene bags (passive samplers) at the exposed sites correlated with rainfall, suggesting that endosulfan entered the riverine environment in runoff from land. At the start of both surveys, in November 1995 and November 1997, there was no significant difference (p &lt; 0.05) between the reference and exposed sites for both total endosulfan concentrations and mean population densities of the combined study taxa. This indicates distance downstream, which was negatively correlated with exposure, was not an important variable in explaining the significantly higher population densities in other months at the reference sites compared with those at sites subsequently exposed to increased (10–25-fold) total endosulfan concentrations. The multivariate analysis of the 1997/98 data with the principal response curves (PRC) method indicated that endosulfan explained a significant proportion (25%) of the variation in the total macroinvertebrate community. Principal components analysis (PCA) indicated other covariables were involved, including river discharge. River discharge was positively correlated to increased densities of the mayfly taxa at the reference sites in the 1995/96 survey, but these correlations were reduced to near zero, except for Baetis sp., in the 1997/98 survey.
Polychlorinated biphenyls, organochlorine pesticides, tris(4-chlorophenyl)methane, and tris(4-chlorophenyl)methanol in livers of small cetaceans stranded along Florida coastal waters, USA
Authors: Watanabe Mafumi , Kannan Kurunthachalam , Takahashi Atsushi , Loganathan Bommanna G , Odell Daniel K , Tanabe Shinsuke , Giesy John P 
Published: March 2010

Abstract
Concentrations of polychlorinated biphenyl congeners (PCBs) and organochlorine pesticides were determined in the livers of bottlenose dolphins, Atlantic spotted dolphins, and pygmy sperm whales found stranded along the coastal waters of Florida, USA, during 1989 to 1994. The PCBs were the most predominant contaminants followed in order by DDTs, chlordanes, tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMOH), hexachlorobenzene, and hexachlorocyclohexane isomers. Among the cetaceans analyzed, organochlorine concentrations were greatest in bottlenose dolphins followed by Atlantic spotted dolphins and pygmy sperm whales. Hexa- and heptachlorobiphenyls were the predominant PCB congeners found in the livers of dolphins. Patterns of relative concentrations of PCB congeners varied among individual bottlenose dolphins. A few individuals contained predominant concentrations of octa- (CB-199, 196/201) and nonachlorobiphenyl (CB-206, 208) congeners, which suggested exposure to the highly chlorinated PCB formulation, Aroclor® 1268, a contaminant at a coastal site in Georgia bordering northern Florida. The estimated 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) of coplanar PCBs in bottlenose dolphins were 170 to 18,000 pg/g, lipid weight (mean: 5,400 pg/g) with mono-ortho congeners 118, 105, and 156 contributing more than 80% of the TEQs. The ratios of CB-169 to CB-126 in cetacean livers were linearly related to total PCB concentrations, which suggested a strong induction of microsomal monooxygenase enzymes in the liver. The hepatic concentrations of TCPMe and TCPMOH in bottlenose dolphins and Atlantic spotted dolphins were greater than those in the blubber of marine mammals of various regions, which suggested the presence of sources for these chemicals along the Atlantic coast of Florida.
Early life-stage mortality in zebrafish (Danio rerio) following maternal exposure to polychlorinated biphenyls and estrogen
Authors: Westerlund Liselotte , Billsson Karin , Andersson Patrik L , Tysklind Mats , Olsson Per-Erik 
Published: March 2010

Abstract
In the present study, specific polychlorinated biphenyl (PCB) congeners were examined for embryo and early life stage mortality in zebrafish (Danio rerio). A set of eight PCBs and two hydroxylated PCBs and 17β-estradiol were tested. Of the compounds tested, 4′-OH-PCB30 (hydroxylated polychlorinated biphenyl) and PCB104 were found to be highly toxic to embryos following maternal exposure and transfer to the oocyte. It was also observed that 17β-estradiol exposure resulted in a high incidence of embryo mortality. Analysis of estrogen receptor levels during embryonic development showed increased mRNA (ribonucleic acid) levels from the 1K stage to 50% epiboly. Following injection of the different compounds, the estrogen receptor mRNA levels were also analyzed in adult male fish to determine if there was a correlation between embryo mortality and estrogenicity of the studied PCBs. The two PCBs that were highly embryo toxic were observed to be estrogenic.
Problems associated with an environmental assessment of organotins: Application to the organic polluted saladillo harbor (southern Spain)
Authors: Gómez-Ariza José Luis , Giraldez Inmaculada , Morales Emilio 
Published: March 2010

Abstract
Problems associated with assessing the environmental effects of organotin (OT) include extraction efficiency, whether to filter the water samples, effect of grain size of sediments, and mobility characteristics of OT species from sediments. This study considered these effects on the six OT species tributyltin, dibutyltin, monobutyltin, triphenyltin, diphenyltin, and monophenyltin in seawater and sediments collected from Saladillo Harbor, a representative enclosed area in southern Spain that receives inputs of both OTs and organic matter. Yields of organotin extracted from sediments with a high organic content by using dichloromethane were higher than those obtained by using pentane. Concentrations of butyltins were higher than those of phenyltins. A gradient was observed of decreasing butyltin concentrations in sediments from 280 ng Sn/g in the inner stations to 0.5 ng/g in the outer stations of the harbor. No dissolved organotin compounds were detected in the overlying seawater. Because OTs are related to the presence of organic matter, iron oxyhydroxides, and phylosilicates, they were strongly adsorbed onto particulate matter in both sediment and suspended matter. Low percentages of butyltins, ranging from undetectable to 0.54%, were released by extracting in unpolluted seawater at pH 8 and 5. Higher concentrations were found in finer sediments.
Evaluation of water-effect ratio methodology for establishing site-specific water quality criteria
Authors: Welsh Paul G , Lipton Joshua , Chapman Gary A 
Published: March 2010

AbstractOne approach outlined by the U.S. Environmental Protection Agency (U.S. EPA) for derivation of site-specific water quality criteria for metals in natural surface waters involves the development of water-effect ratios (WERs). This approach entails multiplying national water quality criteria by an experimentally derived WER, where the WER is defined as the ratio of the toxicity of the metal in the site water to the toxicity of the same metal in standard laboratory water. We discuss technical issues associated with test methods described in the U.S. EPA WER guidance document that may lead to inappropriate WERs. Critical issues include accounting for differences in calcium and magnesium concentrations (Ca:Mg ratios), alkalinity, and pH between site and laboratory waters; ensuring appropriate fish acclimation; and accounting for interspecies variability, multiple metals interactions, end-point variability, and temporal and spatial variability in the derivation of the WER. Failure to address these issues may have the unintended effect of deriving site-specific water quality criteria that are underprotective of aquatic life. We recommend that WER testing and future regulatory guidance for derivation of site-specific water quality criteria incorporate consideration of these potential confounding variables so that site-specific criteria can be established with greater confidence.
Chlorinated pesticide concentrations, with an emphasis on polychlorinated camphenes (toxaphenes), in relation to cytochrome P450 enzyme activities in harp seals (Phoca groenlandica) from the Barents Sea
Authors: Wolkers Hans , Burkow Ivan C , Lydersen Christian , Witkamp Renger F 
Published: March 2010

Abstract
Harp seals (Phoca groenlandica) from the Barents Sea were analyzed for blubber levels of polychlorinated biphenyls (PCBs), polychlorinated camphenes (PCCs; toxaphenes), DDT and its metabolites, hexachlorobenzene (HCB), hexachlorocyclo-hexanes (HCHs), and the cyclodiene pesticides, including dieldrin, endrin, and the chlordanes. Also, the hepatic cytochrome P450 (CYP) enzyme activities were measured to assess a possible relation between CYP activities and pesticide levels. Furthermore, the bioaccumulation potential and persistency of these compounds were evaluated. PCCs were the dominant contaminants, exceeding the PCB concentrations. Individual PCC congener levels (Tox 26 and 50) were fourfold greater than those in the Canadian Arctic and 20-fold greater than those in seals from the west coast of Svalbard, suggesting that the Barents Sea is exposed to PCCs by a local source. The biomagnification factor and the metabolic index were greatest for p,p-DDT, HCB, β-HCH, and the chlordanes trans-nonachlor and U82. The other pesticides showed lesser values, suggesting metabolism. The ethoxyresorufin-O-deethylation activity (CYP1A) was high and not correlated with any of the pesticides, whereas a high correlation (r2 adjusted &gt; 50%) was found between the PCCs and testosterone 6-β hydroxylation activities (CYP3A). This suggests an induction of CYP3A-like activity by PCC exposure.
Dynamics of mercury in blood and feathers of great skuas
Authors: Bearhop Stuart , Ruxton Graeme D , Furness Robert W 
Published: March 2010

Abstract
Mercury dynamics in the blood and feathers of captive great skuas, Catharacta skua, were monitored over 56 weeks. Prior to the onset of molt, mercury intake was solely from their maintenance ration of sprats, Sprattus sprattus. For the first half of molt, in addition to mercury intake from sprats, birds were fed different doses of methylmercuric chloride weekly for 20 weeks. During the second half of molt, dosing was stopped and mercury intake was solely from sprats. Blood was sampled throughout the study and feather growth was monitored. Prior to the onset of molt, mercury concentrations increased over the first 51 to 71 d and appeared to level off after this period. Repeated dosing models based on mammalian pharmacokinetics were, in general, too simplistic to be applicable to the birds in the study. During molt, the elimination of mercury from the blood is probably best described by a three-compartment model. Mercury concentrations in feathers were significantly correlated with those in blood at the time of their growth, suggesting that blood and feathers reflect mercury intake over the same time period. Individuals varied in their ability to excrete ingested mercury into the feathers.
Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, Ukraine
Authors: Rodgers Brenda E , Baker Robert J 
Published: March 2010

Abstract
A population of Clethrionomys glareolus (bank vole) from a highly radioactive area within the Chornobyl, Ukraine exclusion zone was sampled in June 1997 and in June and October 1998. Internal radiation doses from radiocesium were estimated to be as high as 8 rads/d. Total dose, which takes into account the internal dose from radiostrontium and the surrounding environment, was estimated to be 15 to 20 rads/d. In contrast, individuals from a reference population lying outside of the exclusion zone registered negligible levels of contamination. We used the micronucleus test in a double-blind study to analyze blood samples from 58 individuals. We scored more than 600,000 polychromatic erythrocytes (PCEs) but could not reject the null hypothesis that the frequency of micronucleated PCEs in voles exposed to radiation was equal to the frequency in unexposed voles. Results of our study stand in sharp contrast to earlier reports of increased frequencies of micronuclei in rodents exposed to fallout of the Chornobyl accident, but with radiation doses that were orders of magnitude lower than those reported here. Radioresistance and experimental methods are possible explanations for these differences in the results.
Exposure of pacific herring to weathered crude oil: Assessing effects on ova
Authors: Carls Mark G , Hose Jo Ellen , Thomas Robert E , Rice Stanley D 
Published: March 2010

Abstract
In order to determine if exposure to Exxon Valdez oil would adversely affect progeny, reproductively mature Pacific herring were confined in water contaminated with weathered crude oil. Progeny were generally not affected by a 16-d parental exposure to initial aqueous concentrations of ≤58 μg/L total polynuclear aromatic hydrocarbons (PAHs), yielding concentrations of up to 9.7 μg/g in ova. In contrast, previous research indicated that a 16-d direct exposure of herring eggs to similarly weathered oil was detrimental to developing embryos at total initial PAH concentrations of 9 μg/L. Progeny of exposed fish could have been insulated from toxic effects for two reasons. First, as an apparent result of partitioning and metabolism in parental tissues, lower concentrations and less toxic PAHs were preferentially accumulated by ova (primarily naphthalenes; 84–92%). Second, peak exposure concentrations occurred before cell differentiation. The opposite was true for directly exposed eggs; the more toxic multi-ring PAHs (e.g., phenanthrenes and chrysenes) and alkyl-substituted homologues were accumulated, and internal concentrations increased during cell division, differentiation, and organ development. Thus, Pacific herring embryos are more critically sensitive to oil pollution than are gametes.
Uncertainty factors in screening ecological risk assessments
Authors: Duke L Donald , Taggart Mitzy 
Published: March 2010

Abstract
The hazard quotient (HQ) method is commonly used in screening ecological risk assessments (ERAs) to estimate risk to wildlife at contaminated sites. Many ERAs use uncertainty factors (UFs) in the HQ calculation to incorporate uncertainty associated with predicting wildlife responses to contaminant exposure using laboratory toxicity data. The overall objective was to evaluate the current UF methodology as applied to screening ERAs in California, USA. Specific objectives included characterizing current UF methodology, evaluating the degree of conservatism in UFs as applied, and identifying limitations to the current approach. Twenty-four of 29 evaluated ERAs used the HQ approach; 23 of these used UFs in the HQ calculation. All 24 made interspecies extrapolations, and 21 compensated for its uncertainty, most using allometric adjustments and some using UFs. Most also incorporated uncertainty for same-species extrapolations. Twenty-one ERAs used UFs extrapolating from lowest observed adverse effect level (LOAEL) to no observed adverse effect level (NOAEL), and 18 used UFs extrapolating from subchronic to chronic exposure. Values and application of all UF types were inconsistent. Maximum cumulative UFs ranged from 10 to 3,000. Results suggest UF methodology is widely used but inconsistently applied and is not uniformly conservative relative to UFs recommended in regulatory guidelines and academic literature. The method is limited by lack of consensus among scientists, regulators, and practitioners about magnitudes, types, and conceptual underpinnings of the UF methodology.
Evaluation of the dutch environmental risk limits for metals by application of the added risk approach
Authors: Crommentuijn Trudie , Polder Marieke , Sijm Dick , de Bruijn Jack , van de Plassche Erik 
Published: March 2010

Abstract
Recently, environmental quality standards (EQSs) that include background concentrations for metals have been set in The Netherlands. These EQSs are based on environmental risk limits and applying the added risk approach. The added risk approach was developed to incorporate the background concentration of naturally occurring substances such as metals in environmental risk limits. The original approach discriminates between the bioavailable and unavailable fraction and calculates a permissible concentration that can be added to a background concentration, i.e., the maximum permissible addition (MPA). This MPA includes the effects caused by the bioavailable fraction of the background concentration. The new EQSs in The Netherlands assume the bioavailable fraction of background metals is mathematically equal to zero. The rationale for this assumption is that, from an environmental policy perspective, background-related effects that in reality do exist, are desirable because they may in theory lead to increased ecosystem variability or biodiversity. Moreover, there is little information on the bioavailability of background concentrations of metals. This paper presents a theoretical exercise in which the effects of varying background bioavailability on MPA values for cadmium, copper, lead, and zinc in water and soil are evaluated. The results show that, for these metals, bioavailability does not affect or only slightly affects the MPAs. Only the terrestrial MPAs for copper, lead, and zinc are sensitive to bioavailability. This minor influence of assumed percentage bioavailability on the MPAs, coupled with a policy-driven assumption that effects of background concentrations should be ignored, explain the current policy in The Netherlands that the bioavailability of background concentrations of metals should be assumed to be zero.
Thermodynamic estimation of vapor pressure for organophosphorus pesticides
Authors: Tsuzuki Manabu 
Published: March 2010

Abstract
A mthod was developed to estimate vapor pressure of organophosphorus compounds having various functional groups or bond types. The method requires only information on chemical structure of the compounds. The thermodynamic approach using the modified Watson equation was successfully applied to estimate the vapor pressures of organophosphorus pesticides, including phosphorothionates, phosphorodithioates, phosphoramidothioates, phosphates, phosphorothiolates, and phosphorodithiolates. The optimization of the Watson method was found essential for correctly estimating the vapor pressures of organophosphorus compounds, as were the adequate molar refraction of phosphorus atoms in the Eisenlohr correlation and the introduction of an empirical constant for the nitro group in Meissner's equation. The number of possible hydrogen bond sites was found to improve the accuracy of estimated vapor pressures, especially for pesticides possessing the P=O moiety. Our modified Watson equation was used to successfully elucidate the vapor pressure of pesticides ranging from 10−5 to 101 Pa at 298 K and could be used to correctly predict the vapor pressures of other organophosphorus pesticides not utilized in the analysis.
Release of polycyclic aromatic hydrocarbons from contaminated soils by surfactant and remediation of this effluent byPenicilliumspp
Authors: Pinto Linda J , Moore Margo M 
Published: March 2010

AbstractStudies in which surfactants have been employed to increase the bioavailability of soil-bound polycyclic aromatic hydrocarbons (PAHs) have not yielded consistent results. Surfactant mobilization of high molecular weight (MW) PAHs from contaminated soils has not been extensively studied; therefore, the purpose of this research was to compare the extent of release of freshly added high MW 14C-PAH with aged PAH from four different PAH-contaminated soils using a nonionic detergent, Tween 80, and to determine whether Tween 80-solubilized 14C-PAH in soil washings could be degraded by indigenous microorganisms or by added Penicillium spp. Only very high concentrations of Tween 80 (&gt;1,000 times the critical micelle concentration [CMC] for 3 of 4 soils) were able to mobilize bound 14C-pyrene, -chrysene, and -benzo[a]pyrene. The concentration of surfactant required to release 50% of bound 14C-PAH (the SC50 value) ranged from 5 to 30 g/L depending on soil type; a modest correlation was found (0.512) between the fraction of organic carbon in the soil and the SC50 value. At 104 × CMC, Tween 80 released an average of 75% of bound 14C-PAH and 64% of the aged PAH, indicating that the 14C-PAH release only slightly overestimated PAH mobilization from weathered soil. An exception was one soil that had been previously remediated in which &lt;30% of the PAHs were released. The PAH structure had a negligible effect on the mobilization by surfactant because the solubilization curves for all three PAHs were very similar. Tween 80-solubilized 14C-pyrene readsorbed to soil when the surfactant concentration dropped below 103 × CMC. Greater than 90% of the 14C-pyrene in the soil washing effluent could be removed by the addition of spores of active PAH-oxidizing Penicillium spp. plus nutrients. In contrast, &lt;10% of 14C-pyrene was oxidized by the indigenous soil bacteria under the same conditions.