bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting bioavailability and bioaccumulation with in vitro digestive fluid extraction
Authors: Weston Donald P. , Maruya Keith A.
Published: March 2010

Bioavailability of sediment-associated contaminants was assessed in parallel tests by means of a bivalve (Macoma nasuta) bioaccumulation assay and a novel in vitro digestive fluid extraction procedure. Digestive fluid was obtained from the deposit-feeding polychaete Arenicola brasiliensis and used to extract sediments from a U.S. Navy facility. Both the digestive fluid extraction and the bivalve bioaccumulation test identified Cd, Pb, high molecular weight polycyclic aromatic hydrocarbons (HPAHs), and polychlorinated biphenyls (PCBs) as the contaminants of concern; both procedures indicated that As, Cu, Hg, Ni, Zn, and low molecular weight polycyclic aromatic hydrocarbons were rarely, if ever, of concern. The only contaminant for which the techniques consistently differed was Cr, a result attributable to constraints on intestinal absorption of the metal by the bivalves. For Cd and Pb, the concentration attained in digestive fluid during a brief extraction was highly correlated with concentration attained in the bivalve after a 28-d exposure; correlation was marginal for HPAHs and was nonsignificant for PCBs. However, bulk sediment concentrations were equally good predictors of bioaccumulation because of minimal differences in bioavailability from the most contaminated sediments. In vitro contaminant extraction with the digestive fluid assay has potential as a screening tool to predict relative bioaccumulation risk, and has several advantages over traditional tests.
Among- and within-population variability in tolerance to cadmium stress in natural populations of Daphnia magna: Implications for ecological risk assessment
Authors: Barata Carlos , Baird Donald J. , Mitchell Sue E. , Soares Amadeu M. V. M.
Published: March 2010

Previous attempts to test the hypothesis that laboratory selection of isogenetic populations can produce test organisms with a significantly increased mean tolerance to toxic substances have failed. One possible explanation for such failure is that the tolerance of laboratory populations is largely constrained by their origins (were the source populations composed of tolerant genotypes?). To address this question, among- and within-population variability in stress tolerance was assessed by calculating the variance in individual fitness and longevity across a cadmium gradient (0—10 μg/L). The study employed Daphnia magna clones from four geographically separate European populations. Results revealed significant differences in tolerance to lethal levels of toxic stress among populations. The distribution of tolerances within two of the studied populations showed high amounts of genetic variation in tolerance. Genetic relationships between tolerance traits and life history performance under nonstressful environments differed among the studied populations. One population showed significant but low costs associated with tolerance, whereas no costs were associated with tolerance in the other population. These results suggest that laboratory selection will favor individuals with high fitness or reproductive performance under optimal laboratory conditions resulting in laboratory populations with similar or lower tolerance to toxic stress than their original field populations. Given that populations can exhibit high levels of genetic variability in tolerance to toxic stress, minimizing genetic diversity in toxicity tests will increase the uncertainty attendant in extrapolating from the lab to the field.
Methyltransferase: An enzyme assay for microbial methylmercury formation in acidic soils and sediments
Authors: Siciliano Steven D. , Lean David R. S.
Published: March 2010

Methylmercury (MeHg) is a highly toxic form of mercury that bioaccumulates in aquatic food chains. However, methods to reliably identify sites of MeHg formation or to quantify MeHg production require the use of isotopic tracers, which limits their use. In this paper, a method is presented to quantify the methylation of mercury by a methyltransferase pathway. This methyltransferase pathway is one of the biochemical pathways responsible for biological mercury methylation. Protein is extracted from environmental samples, and mercury methyltransferase (HgMT) activity of soil extracts is calculated by assessing increases in methyltransferase activity induced by Hg addition. In enzyme extracts from pure cultures or soil samples, HgMT activity correlated with net MeHg production and Hg consumption, suggesting that HgMT activity can be used to estimate MeHg production in field samples. Over the course of a three-month period in a freshwater wetland, HgMT activity correlated with net MeHg concentrations (r2 = 0.55; p < 0.057). Furthermore, HgMT activity predicted (r2 = 0.80; p < 0.01) gross MeHg formation in freshwater wetlands as well as in laboratory microcosms calculated using previously published rate constants. Our results show that a methyltransferase assay, in combination with demethylation estimates, accurately predicts MeHg formation under field and laboratory conditions. This assay does not require the use of mercury added to field samples to estimate activity but rather estimates the biological activity present in the soil by quantifying the amount of enzyme present in the soil. Such an assay is well suited for use in field surveillance programs assessing MeHg formation in a variety of environments.
Predicting acute zinc toxicity forDaphnia magnaas a function of key water chemistry characteristics: Development and validation of a biotic ligand model
Authors: Heijerick Dagobert G. , De Schamphelaere Karel A. C. , Janssen Colin R.
Published: March 2010

The individual effect of different major cations(Ca2+, Mg2+, Na+, K+, and H+) on the acute toxicity of zinc to the waterflea Daphnia magna was investigated. The 48-h median effective concentration (EC50) in the baseline test medium (i.e., a standard medium with very low ion concentrations) was about 6 μM (Zn2+). An increase of Ca2+ (from 0.25 mM to 3 mM), Mg2+ (from 0.25 mM to 2 mM), and Na+ activity (from 0.077 mM to 13 mM) reduced zinc toxicity by a factor of 6.3, 2.1, and 3.1, respectively. No further toxicity reduction was observed when Ca2+ and Mg2+ activities exceeded 3.0 and 2.0 mM, respectively. Both K+ and H+ did not significantly alter zinc toxicity (expressed as Zn2+ activity). From these data, conditional stability constants for Ca2+ (log K = 3.24), Mg2+ (log K = 2.97), Na2+ (log K = 2.16), and Zn2+ (log K = 5.31) were derived and incorporated into a biotic ligand model (BLM) predicting acute zinc toxicity to D. magna in surface waters with different water quality characteristics. Validation of the developed BLM using 17 media with different pH, hardness, and dissolved organic carbon (DOC) content resulted in a significant correlation coefficient (R2 = 0.76) between predicted and observed 48-h EC50. Eighty-eight percent of the predictions were within a factor of 1.3 of the observed 48-h EC50.
Measurement of triclosan in wastewater treatment systems
Authors: McAvoy Drew C. , Schatowitz Bert , Jacob Martin , Hauk Armin , Eckhoff William S.
Published: March 2010

The objective of this study was to investigate the fate and removal of triclosan (TCS; 5-chloro-2-[2,4-dichloro-phenoxy]-phenol), an antimicrobial agent used in a variety of household and personal-care products, in wastewater treatment systems. This objective was accomplished by monitoring the environmental concentrations of TCS, higher chlorinated derivatives of TCS (4,5-dichloro-2-[2,4-dichloro-phenoxy]-phenol [tetra II]; 5,6-dichloro-2-[2,4-dichloro-phenoxy]-phenol [tetra III]; and 4,5,6-trichloro-2-(2,4-dichloro-phenoxy)-phenol [penta]), and a potential biotransformation by-product of TCS (5-chloro-2-[2,4-dicholoro-phenoxy]-anisole [TCS-OMe]) during wastew ater treatment. These analytes were isolated from wastewater by using a C18 solid-phase extraction column and from sludge with super critical fluid CO2. Once the analytes were isolated, they were derivatized to form trimethylsi-lylethers before quantitation by gas chromatography-mass spectrometry. Recovery of TCS from laboratory-spiked wastewater samples ranged from 79 to 88% for influent, 36 to 87% for final effluent, and 70 to 109% for primary sludge. Field concentrations of TCS in influent wastewater ranged from 3.8 to 16.6 μg/L and concentrations for final effluent ranged from 0.2 to 2.7 μg/L. Removal of TCS by activated-sludge treatment was approximately 96%, whereas removal by trickling-filter treatment ranged from 58 to 86%. The higher chlorinated tetra-II, tetra-III, and penta closans were below quantitation in all of the final effluent samples, except for one sampling event. Digested sludge concentrations of TCS ranged from 0.5 to 15.6 μg/g (dry wt), where the lowest value was from an aerobic digestion process and the highest value was from an anaerobic digestion process. Analysis of these results suggests that TCS is readily biodegradable under aerobic conditions, but not under anaerobic conditions. The higher chlorinated closans were near or below the limit of quantitation in all of the digested sludge samples. Based on results from this study, the chlorinated analogues and biotransformation by-product of TCS are expected to be very low in receiving waters and sludge-amended soils.
The effects of polychlorinated biphenyls (Aroclor 1242) on thyroxine, estradiol, molt, and plumage characteristics in the American kestrel (Falco sparverius)
Authors: Quinn Michael J. , Jr. John B. French , McNabb F. M. Anne , Ottinger Mary Ann
Published: March 2010

The purpose of this experiment was to determine the effects of Aroclor 1242, a mixture of polychlorinated biphenyls (PCBs), on plumage characteristics and molt in the American kestrel, Falco sparverius. Several characteristics of plumage, including color and molt schedule, are modulated by hormonal signals and hence may be modified by endocrine-active contaminants. If so, the functions of plumage (e.g., communication for mating or territorial defense) may be compromised by exposure to such compounds. Captive American kestrels were fed Aroclor 1242 at 0, 6.0, and 60.0 ppm (n = 6 males and 6 females per treatment) mixed in their normal diet. Concentrations of plasma estradiol and thyroxine were measured weekly from the beginning of treatment. Measured plumage characteristics included width of the black subterminal band on the tail, color (a composite index of hue and saturation), reflectance from 230 to 800 nm, pattern of feather loss and regrowth on the tail and wing, and timing of onset and duration of molt. Aroclor 1242 depressed plasma thyroxine. Plasma estradiol levels remained low due to the phase of the breeding cycle. Treatments did not disrupt the measured plumage characteristics. This may be due to timing or dose of exposure or to genetic factors.
Review of the validation of models used in Federal Insecticide, Fungicide, and Rodenticide Act Environmental exposure assessments
Authors: Jmones Russell L. , Mangels Gary
Published: March 2010

The first activity of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Environmental Model Validation Task Force, established to increase confidence in the use of environmental models used in regulatory assessments, was to review the literature information on validation of the pesticide root zone model (PRZM) and the groundwater loading effects of agricultural management systems (GLEAMS). This literature information indicates that these models generally predict the same or greater leaching than observed in actual field measurements, suggesting that these models are suitable for use in regulatory assessments. However, additional validation research conducted using the newest versions of the models would help improve confidence in runoff and leaching predictions because significant revisions have been made in models over the years, few of the literature studies focused on runoff losses, the number of studies having quantitative validation results is minimal, and modelers were aware of the field results in most of the literature studies. Areas for special consideration in conducting model validation research include improving the process for selecting input parameters, developing recommendations for performing calibration simulations, devising appropriate procedures for keeping results of field studies from modelers performing simulations to validate model predictions while providing access for calibration simulations, and developing quantitative statistical procedures for comparing model predictions with experimental results.
Distribution of chlorinated hydrocarbons in overlying water, sediment, polychaete, and hornyhead turbot (Pleuronichthys verticalis) in the Coastal ocean, Southern California, USA
Authors: Zeng Eddy Y. , Tran Kim
Published: March 2010

1, 1, 1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its primary metabolites (DDTs) and polychlorinated biphenyls (PCBs) are a major source of concern in the Southern California Bight (SCB), USA. The fate of DDTs and PCBs is a key element in assessing the effects imposed by these potential carcinogens on the marine ecosystem. We found that DDTs and PCBs remained widely distributed in the overlying water, sediment, polychaetes, and liver and muscle tissues of the hornyhead turbot (Pleuronichthys verticalis) collected from three nearshore locations of the SCB with different levels of contamination. Student's t tests indicated that the measured partition coefficients between the nonaqueous phases (sediment, polychaete, and fish) and overlying water at a heavily contaminated location were significantly greater than those predicted by the equilibrium partitioning theory (EPT). Measured partition coefficients between the nonaqueous phases and overlying water for a few DDT components at two other stations (moderate and low contamination) were also generally greater than the EPT predictions. On the other hand, DDTs and PCBs in polychaetes and fish tissues may be taken up from sediments via equilibrium partitioning or from food sources. These findings are suggestive of the possibility that contaminated sediments may have become an important source of contamination.
Responses of songbirds to aerial spraying of the microbial insecticide Bacillus thuringiensis var. kurstaki (Foray 48B®) on Vancouver Island, British Columbia, Canada
Authors: Sopuck Lennart , Ovaska Kristiina , Whittington Bruce
Published: March 2010

Use of bacterial insecticides containing Bacillus thuringiensis var. kurstaki (Btk) is gaining popularity as an environmentally safe control measure against lepidopteran pests, but indirect effects on nontarget organisms through reduced prey base have received little attention. Aerial spraying of Btk (Foray 48B®) over a 12,803-ha area on southeastern Vancouver Island (BC, Canada) in May to June 1999 as part of a gypsy moth (Lymantria dispar) control program provided us with an opportunity to examine the responses of songbirds to spray application. To obtain an estimate of species richness and relative abundance, we conducted standard songbird point-count surveys in Garry oak (Quercus garryana)-dominated habitats in Btk-sprayed and unsprayed areas in April to June 1999 and, one year after spraying, in 2000. These surveys revealed no patterns consistent with adverse effects of spraying on the relative abundance of adult birds or singing males for any of the species, whether examined individually or when combined into foraging guilds. An exception was the spotted towhee (Pipilo maculatus), which in 1999, but not in 2000, occurred at significantly lower numbers in sprayed plots after Btk treatment. Intensive searches of plots in sprayed and unsprayed areas revealed no differences in the numbers of songbird broods between the two areas for any of the species examined.
Asia-Pacific mussel watch: Monitoring of butyltin contamination in coastal waters of Asian developing countries
Authors: Sudaryanto Agus , Takahashi Shin , Monirith In , Ismail Ahmad , Muchtar Muswerry , Zheng Jinshu , Richardson Bruce J. , Subramanian Annamalai , Prudente Maricar , Hue Nguyen Duc , Tanabe Shinsuke
Published: March 2010

Butyltin compounds (BTs) including mono-, di-, and tributyltin and total tin (ΣSn), were determined in green mussels (Perna viridis) from various Asian developing countries, such as Cambodia, China (Hong Kong and southern China), Malaysia, India, Indonesia, the Philippines, and Vietnam, to elucidate the contamination status, distribution, and possible sources and to assess the risks on aquatic organisms and humans. Butyltin compounds were detected in green mussels collected from all the sampling location investigated, suggesting widespread contamination of BTs along the coastal waters of Asian developing countries. Among butyltin derivatives, tributyltin (TBT) was the predominant compound, indicating its ongoing usage and recent exposures in Asian coastal waters. Higher concentrations of BTs were found in mussels collected at locations with intensive maritime activities, implying that the usage of TBT as a biocide in antifouling paints was a major source of BTs. In addition, relatively high concentrations of BTs were observed in mussels from aquaculture areas in Hong Kong and Malaysia, as it has been reported in Thailand. With the recent improvement in economic status in Asia, it is probable that an increase in TBT usage will occur in aquaculture. Although contamination levels were generally low in mussel samples from most of the Asian developing countries, some of those from polluted areas in Hong Kong, India, Malaysia, the Philippines, and Thailand revealed levels comparable to those in developed nations. Furthermore, the concentrations of TBT in some mussels from polluted areas exceeded the threshold for toxic effects on organisms and estimated tolerable average residue levels as seafoods for human consumption. A significant correlation was observed between the concentrations of ΣBTs and ΣSn in mussels, and ΣBTs were made up mostly 100% of ΣSn in mussels taken from locations having intensive maritime/human activities. This suggests that anthropogenic BTs represent the major source of tin accumulation in mussels. To our knowledge, this is a first comprehensive report on butyltin pollution monitoring in developing countries in the Asia-Pacific region.
Endocrine disruptors in sewage treatment plants, receiving river waters, and sediments: Integration of chemical analysis and biological effects on feral carp
Authors: Petrovic Mira , Solé Montserrat , López De Alda María J. , Barceló Damià
Published: March 2010

Occurrence of alkylphenol ethoxylates or their metabolites (alkylphenols and carboxylated derivatives), as well as natural and synthetic steroids in sewage treatment plant (STP) effluents and in their receiving waters, has been related to biological effects, measured as alterations of plasma vitellogenin (VTG) concentration in natural fish populations. Water composites of STP influents, effluents, sludge, river water, sediment, and feral carps (Cyprinus carpio) were analyzed over a seven-month period in two tributaries of the Llobregat River (NE Spain). Solid-phase extraction/liquid chromatography/mass spectrometry (SPE-LC-MS) analysis revealed concentrations of up to 31 μg/L for nonylphenol ethoxylates (NPEOs), 15 μg/L for nonylphenol (NP), and 35 μg/L for nonylphenoxy carboxylate (NPE1C) in river water downstream of STPs. These compounds were also found to accumulate in river sediment with concentrations ranging from 10 to 820 μg/kg of NPEOs and from 22 to 645 μg/kg for NP. Natural and synthetic estrogens and progestogens also occurred in the water and sediments analyzed but in the ng/L and μg/kg range, respectively. Vitellogenin fluctuated among sites and sampling periods, but it was found to be increased in male carp collected downstream of the main STP. A correlation between endocrine-disrupting compounds (EDCs) in water and sediment and plasma VTG concentration in male carp was observed, especially for alkylphenolic compounds in water and sediment samples (r = 0.83–0.84 for n = 24) and for estriol and estrone in water (r =0.78 and 0.94 for n = 9 and 8, respectively).
Genetic and demographic responses of mercury-exposed mosquitofish (Gambusia holbrooki) populations: Temporal stability and reproductive components of fitness
Authors: Tatara Christopher Paul , Mulvey Margaret , Newman Michael C.
Published: March 2010

Two previous mesocosm studies showed changes in glucosephosphate isomerase-2 (Gpi-2) allele frequencies in mosquitofish populations exposed to mercury for 111 d or two years. A previous selection component analysis of single-generation populations exposed for 111 d to 18 μ/L Hg suggested that female sexual selection and fecundity selection could contribute to changes in Gpi-2 allele frequencies. The present multigeneration study was conducted to determine the stability of Gpi-2 allele frequencies over four years of mercury exposure, measure the reproductive fitness of Gpi-2 genotypes inhabiting control and mercury-contaminated mesocosms to determine a mechanism explaining changes in Gpi-2 allele frequencies, investigate differences in the demographic characteristics of mercury-exposed and control populations, and investigate the water quality of the mesocosms to determine if variables other than mercury show concordant patterns among mesocosms. Differences in Gpi-2 allele frequencies between control and mercury-exposed populations were stable over four years (˜ eight generations) of mercury exposure. Mercury-exposed female mosquitofish had a lower probability of being gravid than control females (p = 0.001). Mercury-exposed females also had lower fecundity (total number of eggs and embryos) than control females (p = 0.036). Unlike the results of the more intense mercury exposures in the single generation study, no strong evidence was found that Gpi-2 genotype influenced fecundity or the probability of being gravid in both control and mercury-exposed females. The quantification of fitness components is difficult but has the potential to enhance our understanding of how toxicants alter allele frequencies in exposed populations.
An evaluation of the success of dredging as remediation at a DDT-contaminated site in San Francisco Bay, California, USA
Authors: Weston Donald P. , Jarman Walter M. , Cabana Gilbert , Bacon Corinne E. , Jacobson Lisa A.
Published: March 2010

Lauritzen Canal, a portion of San Francisco Bay near Richmond, California, USA, was heavily contaminated with dichlorodiphenyltrichloroethane (DDT) and dieldrin as a result of releases from a pesticide-formulating firm. In 1996 and 1997, 82,000 m3 of contaminated sediment was removed from the canal by dredging. This study evaluated the success of the dredging based largely on body burdens of DDT and its metabolites (ΣDDT) in resident biota, with some data on sediment- and water-contaminant levels and sediment toxicity testing. Sediment disturbance during dredging introduced a pulse of ΣDDT into the Lauritzen Canal ecosystem, and body burdens of fish and invertebrates increased 2- to 76-fold, depending on the species. Approximately 11/2 years after remediation, 11 of 14 indicators showed contamination comparable with or worse than the contamination that existed prior to dredging. Monitoring of mussels up to four years postdredging suggests some modest improvement, although the ΣDDT body burden of canal mussels remained far above the norm for San Francisco Bay. The elevated ΣDDT body burdens in biota that persisted for years after remediation reflect recent exposure and are not merely a result of slow metabolic elimination of the ΣDDT pulse associated with dredging. Sediment ΣDDT concentrations were low immediately after dredging, but within months, the canal bottom became covered with a veneer of fine sediment as contaminated as that that had been removed. The source of this material has not been conclusively established, but we suspect it came from slumping and erosion from the flanks of the canal beneath docks and around pilings where dredging was not done. In retrospect, either capping in place or more thorough dredging may have been more successful in reducing pesticide exposure of the biota, although there were difficulties associated with both alternatives.
Influence of sorbate planarity on the magnitude of rapidly desorbing fractions of organic compounds in sediment
Authors: van Noort Paul C. M. , Cornelissen Gerard , ten Hulscher Theodora E. M. , Belfoid Angelique
Published: March 2010

Organic compounds in sediments are known to distribute between rapid, slowly, and very slowly desorbing sites. This distribution is relevant to bioavailability and risk assessment of organic compounds in sediment. In this study, the fraction desorbing to Tenaxr̀ in 6 h was measured for a range of organic compounds in sediment differing in their extent of planarity. The aim was to determine the influence of the extent of planarity on the distribution over the rapidly desorbing sites on the one hand and the slowly and very slowly desorbing sites on the other. The magnitude of rapidly desorbing fractions, calculated from the fractions desorbed to Tenax in 6 h, decreased with increasing extent of planarity, expressed as sorbate thickness. For a thickness of less than 5.5 to 6 AÅ, rapidly desorbing fractions are approximately equal to those for fully planar compounds, such as polycyclic aromatic hydrocarbons, which have a thickness of about 3 Å. This is in agreement with previously reported differences in sediment-water distribution coefficients between planar polycyclic aromatic hydrocarbons (PAHs) and nonplanar PCBs. The present findings suggest that simple molecular modeling of the thickness of nonplanar organic compounds enables the estimation of the affinity for rapidly desorbing sites relative to planar compounds.
Pacific steelhead (Oncorhynchus mykiss) exposed to chlorpyrifos: Benchmark concentration estimates for acetylcholinesterase inhibition
Authors: Sandahl Jason F. , Jenkins Jeffrey J.
Published: March 2010

Steelhead trout (Oncorhynchus mykiss) were exposed for 96 h to the organophosphate chlorpyrifos to establish benchmark concentration (BMC) values in the low-effect range of brain acetylcholinesterase (AChE) inhibition. The U.S. Environmental Protection Agency (U.S. EPA) benchmark dose software was used to model the data. Benchmark concentrations were determined for a range of inhibition levels at 5, 10, and 20%, at 1 and 2 control standard deviations (SD), and at an experimental limit-of-detection level of 2.5%. One contributing difficulty in establishing precise inhibition BMCs in the lower effect region is the variability associated with the AChE analytical method. To minimize this variability, the Ellman method was modified specifically for analysis of O. mykiss brain tissue. Laboratory-established BMCs for chlorpyrifos were then compared with the U.S. EPA 96-h water quality criteria and with the concentration levels detected in Northwest surface waters that are home to threatened steelhead trout. The U.S. EPA 96-h water quality criteria of 0.083 μg/L is below the BMC02.5, the limit-of-detection value for this study. The average chlorpyrifos concentration detected during a two-week period in one monitored stream was 0.127 μg/L, which approaches the BMC02.5. The peak chlorpyrifos concentration detected at 0.482 μg/L is near the BMC1SD estimate.
Differential sensitivity of four Lobaria lichens to copper in vitro
Authors: Cabral João Paulo
Published: March 2010

Treatment of Lobaria amplissima, Lobaria pulmonaria, Lobaria scrobiculata, and Lobaria virens with 0 to 500 μM CuSO4 for 0 to 120 min at 25.0°C resulted in a time- and copper-concentration-dependent decrease in the thallus total potassium content and a release of K+ from the thallus, indicating that copper damaged the cytoplasmic membrane of the fungal hyphae. Lobaria pulmonaria was the most sensitive species, L. virens the most resistant to copper treatment. Lobaria amplissima and L. scrobiculata displayed intermediate sensitivity. Treatment with copper also resulted in a time-dependent increase in the thallus copper content. For all four Lobaria species, the thallus potassium content decreased linearly with increasing thallus copper content, suggesting that, as cupric ions bound to the thallus, they reach target sites in the membrane. Acetone extracts contained low concentrations of chlorophyll a, amino acids, polyols, and sugars, but detectable or considerable amounts of lichen substances, i.e., constictic, norstictic, stictic, and usnic acids and scrobiculin. Titration of the extracts with copper and assay of free Cu2+ revealed the presence of copper-binding ligands, most probably corresponding to the lichen substances detected in the extracts. Acetone extracts of L. amplissima and L. virens bound small or very small amounts of Cu2+; binding was monophasic and probably involved scrobiculin. Acetone extracts of L. pulmonaria and L. scrobiculata bound high or intermediate amounts of copper; binding was polyphasic and probably involved the lichen acids detected in the extracts. It was concluded that, in the studied Lobaria species, acetone extracts containing lichen substances could bind, in vitro, considerable amounts of Cu2+, but this binding did not prevent membrane damage in the thallus. Several hypotheses are presented to explain these results.
Prediction of soil sorption coefficients with a conductor-like screening model for real solvents
Authors: Klamt Andreas , Eckert Frank , Diedenhofen Michael
Published: March 2010

Using a general theory for partition coefficients based on a quantum chemically derived conductor-like screening model for real solvents σ-moment descriptors, the logarithmic soil sorption coefficients log KOC of a database of 440 compounds has been successfully correlated, achieving a standard deviation (root-means-squared [RMS]) of 0.62 log-units on the training set and a predictive RMS of 0.72 log-units on a more demanding test set. The quality of this generally applicable predictive approach is almost the same as that of a regression of log KOC with experimental log KOW values, which are the best correlations currently available. The error of this new predictive method is only approximately 43% of the error of a recently published model using a different quantum chemically based approach.
Interclonal variation of heavy metal interactions in Salix viminalis
Authors: Landberg Tommy , Greger Maria
Published: March 2010

In the complex chemistry of soil, interactions between metals can be expected and these affect the uptake of the metals by the plants. The role of the metal–metal interaction may vary between different plants. This study was performed to investigate if variations exist in the interactions between Cd, Cu, and Zn on toxicity and accumulation of these metals in different clones of Salix viminalis. Two studies were performed. First, to study interaction at uptake, 10 clones with high or low accumulation capacity of Cd, Cu, and Zn, respectively, were treated with 0.3 μM Cd, 0.1 μM Cu, and 3 μM Zn (all three metals at the same time or separately). Second, to study the effect of one of the metals on the sensitivity of the plant to the other metals, three clones with high or low sensitivity to each of the three metals were used in a modified Weibull analysis. Examination of the results shows that interclonal variation exists in effects of metal interaction on metal accumulation and sensitivity exists. The uptake experiment showed that accumulation of Cu was decreased by the other metals, but only in clones with high Cu-accumulating properties because of decreased net uptake of Cu. The accumulation of Zn in roots was increased two- to threefold in all clones in the presence of the other metals because of a decreased translocation of Zn to the shoot. The accumulation of Cd was not changed by the presence of the other metals in any of the clones. The second experiment showed that the effect of interactions between the different metals on metal toxicity was present in all clones but appeared most frequently in the clone with high Zn resistance. Synergistic effects between Cu and Zn in the Zn-resistant clone suggested that this clone had evolved an additional site of toxic action that was absent in the other clones.
Reduction of estrogenic activity of municipal wastewater by aerated lagoon treatment facilities
Authors: Bringolf Robert B. , Summerfelt Robert C.
Published: March 2010

The estrogenic activity of municipal wastewater in aerated lagoon treatment facilities was evaluated using plasma concentrations of vitellogenin (Vtg) in male fathead minnows (Pimephales promelas). Caged fathead minnows were exposed for 10 to 12 d in three lagoons that are connected in series at each of 10 municipal wastewater treatment facilities in central Iowa. USA, during October and November 2000. Fathead minnows held in the laboratory served as unexposed controls. Pooled (n = 4–10 fish) plasma Vtg, quantified by enzyme-linked immunosorbent assay (ELISA), was 1,702 ± 670 (mean ± standard error [SE]) μg/ml in the first lagoons (n = 9), 0.94 ± 0.36 μg/ml in the second lagoons (n = 10), and 0.04 ± 0.02 μg/ml in the third lagoons (n = 8). Differences in mean fish plasma Vtg concentration among lagoons were highly significant (p < 0.001). The mean concentration of plasma Vtg in fish in the third lagoons was not significantly different (p = 0.990) from that of the control fish (0.04 ± 0.02 μg/ml). Plasma Vtg concentrations of fish in the first lagoons were inversely correlated with wastewater retention time in the lagoons (p = 0.002, r = −0.877). Water temperatures of the final effluents during the study ranged from 9 to 12°C General treatment efficiency of lagoons has been shown to be dependent on temperature, so the potential exists for decreased removal of estrogenic activity when water temperatures are lower (e.g., winter months) than the present study. In conclusion, wastewater entering aerated lagoon systems was estrogenic to fish, but with serial passage through the lagoons, the estrogenic activity decreased to a level that was not sufficient to induce vitellogenesis in male fathead minnows in a 10- to 12-d exposure.
Construction and evaluation of a transgenichsp16-GFP-lacZ Caenorhabditis elegansstrain for environmental monitoring
Authors: David Helen E. , Dawe Adam S. , de Pomerai David I. , Jones Don , Candido E. Peter M. , Daniells Clare
Published: March 2010

A novel integrated transgenic Caenorhabditis elegans strain (PC 161) incorporates a double reporter construct with green fluorescent protein (GFP) and lacZ genes fused in-frame into the second exon of the hsp16–1 gene. This construct also includes the Simian Virus 40 (SV40) nuclear localization signal such that the fusion protein accumulates in the nuclei of expressing cells. The PC161 strain was used to monitor the effects of several known stressors, including heat, cadmium, and microwave radiation. The time course of induction was similar for both reporters but was strongly influenced by pretreatment conditions. The PC161 worms kept at 15°C beforehand showed a steady increase in reporter expression (up to at least 16 h) when heated to 30°C. However, if washed on ice prior to heat stress at 30°C, PC161 worms showed a much steeper rise in reporter expression, reaching a maximum after 2.5 h and then plateauing. Heat shock induced strong expression of both reporter genes in all tissues apart from the germ line and early embryos. A highly significant linear dose-response relationship was observed for both transgenes with increasing cadmium concentrations (5–100 μg/ml). Prolonged exposure to microwave radiation (750 MHz and 0.5 W for 16 h) also induced expression of both transgenes at 25 and (to some extent) 27°C, but only β-galactosidase activity was detectable at 23°C, and neither reporter was detectably expressed at 21°C Throughout all exposures, the lacZ reporter product was more readily detectable than coexpressed GFP. However, the GFP reporter affords opportunities to monitor the stress response in living worms.
Studies on bioremediation of polycyclic aromatic hydrocarbon-contaminated sediments: Bioavailability, biodegradability, and toxicity issues
Authors: Tabak Henry H. , Lazorchak James M. , Lei Li , Khodadoust Amid P. , Antia Jimmy E. , Bagchi Rajesh , Suidan Makram T.
Published: March 2010

The widespread contamination by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective bioremediation processes. This research studied a chronically PAH-contaminated estuarine sediment from the East River (ER; NY, USA) characterized by high concentrations of PAHs (∼4–190 ppm), sulfide, and metals and a marine sediment from New York/New Jersey Harbor (NY/NJH; USA) with only trace quantities of PAHs (0.1–0.6 ppm). The focus was to examine the relationship between bioavailability of PAHs and their biological removal in a slurry system. Freshwater and marine sediment toxicity tests were conducted to measure baseline toxicity of both sediments to amphipods, aquatic worms, fathead and sheepshead minnow larvae, and a vascular plant; to determine the cause of toxicity; and to evaluate the effectiveness of the biotreatment strategies in reducing toxicity. Results showed the ER sediment was acutely toxic to all freshwater and marine organisms tested and that the toxicity was mainly caused by sulfide, PAHs, and metals present in the sediment. In spite of the high toxicity, most of the PAH compounds showed significant degradation in the aerobic sediment/water slurry system if the initial high oxygen demand due to the high sulfide content of the sediment was overcome. The removal of PAHs by biodegradation was closely related to their desorbed amount in 90% isopropanol solution during 24 h of contact, while the desorption of model PAH compounds from freshly spiked NY/NJH sediment did not describe the bioavailability of PAHs in the East River sediment well. The research improves our understanding of bioavailability as a controlling factor in bioremediation of PAHs and the potential of aerobic biodegradation for PAH removal and ecotoxicity reduction.
Slow-stirring method for determining then-octanol/water partition coefficient (pow) for highly hydrophobic chemicals: Performance evaluation in a ring test
Authors: Tolls Johannes , Bodo Karina , De Felip Elena , Dujardin Roland , Kim Yong Hwa , Moeller-Jensen Lars , Mullee Darren , Nakajima Ayako , Paschke Albrecht , Pawliczek Jürgen-Bernd , Schneider Jürgen , Tadeo José-Luis , Tognucci Alessandra C. , Webb Jim , Zwijzen A. Corneel
Published: March 2010

The n-octanol/water partition coefficient (Pow) is one of the most important parameters employed for estimating a chemical's environmental fate and toxicity. The currently adopted test guidelines for its determination do not allow for reliable determination of log Pow greater than 5. The slow-stirring experiment, in contrast, has been demonstrated to provide reliable log Pow data up to log Pow of 8.3. To validate this method and to obtain its approval as an official Organization for Economic Cooperation and Development (Paris, France) test guideline, a ring test was performed to evaluate the accuracy and precision of the slow-stirring experiment for determination of log Pow, particularly for highly hydrophobic compounds. Up to 15 volunteer laboratories tested 1,2,3,4-tetrachlorobenzene, hexachlorobenzene, 2,2′,3,3′,5,5′,6,6′-octachlorobiphenyl, and decachlorobiphenyl (4.5 < log Pow < 8.2). The ring-test results for the respective chemicals were 4.62, 5.50, 7.39, and 8.18. The results deviated by less than 0.1 log Pow units from the reference log Pow. In addition, the relative standard deviations of log Pow were less than 2%. Using the protocol of the ring test, log Pow of p,p′-DDT was determined to be 6.24 ± 0.05 (mean ± standard deviation). In combination, these results indicate that the slow-stirring method is precise and accurate and, thus, allows for reliable determination of log Pow of highly hydrophobic chemicals.
Degradation of nonylphenol ethoxylates in estuarine sediment under aerobic and anaerobic conditions
Authors: Lee Ferguson P. , Brownawell Bruce J.
Published: March 2010

Nonylphenol ethoxylate (NPEO) surfactants and their metabolites are ubiquitous contaminants of the aquatic environment. Despite considerable interest in the environmental fate of these compounds due to concerns over toxicity and estrogenic activity, the pathways of NPEO degradation in sediments have not previously been reported, in spite of the fact that sediment appears to be an important sink for these compounds in the environment. In the present work, we have examined the rates and pathways of NPEO degradation in batch sediment slurry experiments using radiolabeled NPEO mixtures. Results suggest that NPEOs are more persistent in sediments under anaerobic conditions than in the presence of oxygen. In addition, it was illustrated that NPEO degradation proceeds via separate pathways in oxic and anoxic sediment. Discernible metabolites were identified and an overall mass balance for NPEO degradation in oxic and anoxic sediment was achieved. In contrast with previous studies, no evidence was observed for net production of nonylphenol from NPEOs during aerobic or anaerobic degradation. The observed relative rates at which NPEO ethoxymers disappeared in the sediment slurry experiments were consistent with previous reports for these compounds in sediment and other environmental media, although the absolute rates measured were somewhat faster than those reported for field sediments.
The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L.
Authors: Lalah Joseph O. , Behechti Akbar , Severin Gabriele F. , Lenoir Dieter , Günther Klaus , Kettrup Antonius , Schramm Karl-Werner
Published: March 2010

A single branched isomer of p-nonylphenol, 4(3′,6′-dimethyl-3′-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 μg/L (range: 92–116 μg/L) in water at 19°C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 μg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3′,6′-dimethyl-3′-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with β-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.
Organochlorine contaminants in body tissue of free-ranging white-tailed eagles from northern regions of Germany
Authors: Kenntner Norbert , Krone Oliver , Oehme Günter , Heidecke Dietrich , Tataruch Frieda
Published: March 2010

Concentrations of the organochlorine pesticides hexachlorobenzene (HCB), γ-hexachlorocyclohexane (γ-HCH), DDT and its metabolite p,p′-dichlorodiphenyldichloroethylene (DDE), and seven polychlorinated biphenyl (PCB) congeners were analyzed in livers and adipose tissue samples of 145 white-tailed eagles found dead or moribund in Germany from 1979 to 2001. Most birds were found in the region of the former German Democratic Republic where the insecticide DDT was used until 1988. Therefore, our samples represent mainly residue data of specimens following the ban of DDT in these regions. Contaminant levels of 127 immature and adult birds found between the years 1990 and 2001 were in general below threshold levels known for detrimental effects. The highest level of σDDT was detected in an adult bird found dead in 1979. Residues of most organochlorines were highly significantly correlated between hepatic and adipose tissue. Concentrations of σDDT increase during aging, whereas only the levels of the higher-chlorinated PCBs were higher in tissues of adult birds compared with the younger age classes. Hepatic residues of σDDT and HCB and the ratio of σDDT to σPCB, respectively, were significantly declining from 1990 to 2001. The indices given for body condition of specimen were significantly correlated with liver concentrations, indicating higher residues in more emaciated birds.
Stable isotopes and fatty acids reveal thatChironomus ripariusfeeds selectively on added food in standardized toxicity tests
Authors: Åkerblom Nina , Goedkoop Willem
Published: March 2010

During long-term standardized toxicity tests with Chironomus riparius, food additions are a prerequisite for normal development and to avoid false-positive results. Consequently, larvae may selectively feed on added food rather than on contaminated sediment, which may confound toxicity test results. We designed a feeding study and estimated the degree of feeding on different food resources by using stable isotope and fatty acid (FA) analyses. In one treatment, larvae were offered both artificial sediment (peat, kaolin clay, sand, and calcium carbonate) and added food (TetraPhyllr̀), whereas larvae in the two other treatments had access to either one of these potential food items. The highest biomass and survival were found among larvae with access to both artificial sediment and TetraPhyll. Two-source mixing models revealed that larval Chironomus that were offered both TetraPhyll and artificial sediment obtained 94 ± 6.9% of their carbon and 90 ± 4.3% of their nitrogen from added TetraPhyll. Larvae with access to only sediment had lower Δ13C and Δ15N (–23.34 ± 0.56%‰ and 0.33 ± 0.52%‰) than those that were offered both sediment and TetraPhyll (–20.95 ± 0.13%‰ and 7.45 ± 0.36%‰) or only TetraPhyll (–20.17 ± 0.20%‰ and 7.82 ± 0.15%‰). In addition, FA composition of larvae that were offered both artificial sediment and TetraPhyll closely resembled that of those fed exclusively TetraPhyll. These results show that larval Chironumus strongly prefer added food, rather than artificial sediment in long-term toxicity tests. This preferential feeding behavior affects exposure pathways and ultimately toxicity test results.