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Growing concern about the environmental impact of ionizable and polar organic chemicals such as pesticides, pharmaceuticals and personal care products has lead to the inclusion of some in legislative and regulatory frameworks. It is expected that future monitoring requirements for these chemicals in aquatic environments will increase, along with the need for low cost monitoring and risk assessment strategies. In this study the uptake of 13 neutral and 6 ionizable pesticides, pharmaceuticals and personal care products by modified POCIS (with Strata™-X sorbent) and Chemcatchers™ (SDB-RPS or SDB-XC) was investigated under controlled conditions at pH = 6.5 for 26 days. The modified POCIS and Chemcatcher™ (SDB-RPS) samplers exhibited similar performance with the uptake of the majority of the 19 chemicals of interest categorised as linear over the 26 day deployment. Only a few ionized herbicides (picloram and dicamba) and triclosan showed negligible accumulation. Chemcatcher™ with SDB-XC sorbent performed relatively poorly with only carbamazepine having a linear accumulation profile, and 8 compounds showing no measurable accumulation. Differences in the uptake behavior of chemicals were not easily explained by their physico-chemical properties, strengthening the requirement for detailed calibration data. PES membranes accumulated significant amount of some compounds (i.e. triclosan and diuron), even after extended deployment (i.e. 26 days). At present there is no way to predict which compounds will demonstrate this behavior. Increasing membrane pore size from 0.2 to 0.45 µm for Chemcatcher™ (SBD-RPS) caused an average increase in Rs of 24%.

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The uptake and accumulation of organic contaminants by plants can be detrimental to the plant itself as well as consumers. Tetracycline antibiotics are present at trace levels in soil and water. Under typical environmental conditions, they exist as zwitterions. Comparatively little is known of their uptake and accumulation by plants, or the mechanism by which this occurs. To examine this, rice (Oryza sativa L.) was employed, together with a static diffusion cell equipped with a cellulose membrane as a model for the uptake process. For rice, kinetic results suggested that the zwitterions were behaving similarly to neutral organic compounds, with a passive uptake process. The diffusion cell provided qualitatively similar results. When exposed to aqueous concentrations of zwitterionic tetracyclines of 50 mg L(-1) over 15 days, no translocation to shoots or detrimental effects on plants was observed. Despite relatively low root lipid contents, concentrations in root tissue of greater than 1000 mg kg(-1) (d.w.) were determined with maximum Root Concentration Factors of the order of 2000 L kg(-1) (d.w.). Overall, for the tetracyclines investigated, kinetic and accumulation behavior in plants together with permeation in the diffusion cell were all governed by compound hydrophobicity.

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Soil of former shrimp aquaculture facilities in Thailand may be contaminated by antibiotics (e.g. oxytetracycline and norfloxacin) and have elevated salinity. Therefore, reuse of this land can be problematic. The utility of soybean (Glycine max (L.) Merr.) for phytoremediation was investigated. The rate of germination and seedling emergence in prepared contaminated soil (conductivity 17.7 dS m(-1) from adding 70 mg sodium chloride g(-1) dry weight, 105 mg kg(-1) dry weight oxytetracycline and 55 mg kg(-1) dry weight norfloxacin) in sunlight was approximately 80% that of uncontaminated soil. This reduction was largely due to the high salinity. The antibiotics of interest degraded relatively rapidly in soil (half-life <10h for both) but loss was slower in deionised water. Accumulation of the antibiotics from deionised water by soybean resulted in little effect on growth rate and maximum levels in plants were observed after two days exposure, followed by declining concentrations. For soybean plants grown in saline soil, 90% removal of NaCl from soil adjacent to plant roots was observed, most within two days. Wilting and defoliation occurred, but plants recovered after 10 days and maximum salt levels in plants exceeded 20,000 mg g(-1) dry weight with translocation from root to shoot tissue noted. Soybean plants also accumulated the antibiotics from prepared contaminated saline soil, but translocation from the roots was not observed. The results showed that soybean can be valuable for phytoremediation in these situations.

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This paper describes the results of research examining the effect of dissolved organo-metallic complexes of copper (Cu) and zinc (Zn) from sewage sludge leachate on sorption by a humic-gley soil A-horizon, and the influence of such complexes on resultant sludge loading estimates. Sorption was described with Linear, Freundlich or Langmuir equations, and compared between a sample of sludge leachate (containing 97.4% of Cu and 63.2% of Zn as dissolved organo-metallic complexes) and a reference solution (which mimicked the leachate, except for a lack of dissolved organic material). This comparison revealed that dissolved organo-metallic complexes significantly depressed Cu and Zn sorption in the study soil. The isotherm equations were then used to estimate sludge-derived Cu and Zn loadings to soil in order to result in an "allowable" output concentration from the soil solution to the surrounding environment. These loadings, together with soil bulk density and "availability" of sludge Cu and Zn, were incorporated in a preliminary model to estimate sludge application rates which are acceptable in terms of off-site movement of these metals through leaching losses. In the absence of dissolved organo-metallic complexes (sorption from the reference solution), levels of Cu and Zn sorption in the study soil indicated a sludge application rate of approximately 3500 kg/ha. However, when Cu and Zn sorption from the sludge leachate with dissolved organo-metallic complexes was considered, calculated loading rates were reduced to approximately 690 kg-sludge/ha. This suggests that for sludge loading estimates based on soil sorption characteristics to be relevant to environmental protection, the sorption depressing effect of dissolved organo-metallic complexes should be quantitatively considered.

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To determine the extent of metal accumulation in some aquatic macrophytes from contaminated urban streams in southeast Queensland, plants were sampled from six sites, along with contiguous sediments. In all, 15 different species were collected, the most common genera being Typha (Cattails or Bulrushes) and Persicaria (Knotweeds). Before heavy metal analysis, plants were further separated into various morphological tissues, and five selected samples were separated into various physiological tissues. The cadmium, copper, lead and zinc content of the plants were analysed using flames AAS. In general, plant roots exhibited higher metal concentrations than the contiguous sediments. Of the metals of interest, only for zinc was there a relatively clear pattern of increasing accumulation in aquatic macrophytes with increasing sediment metal concentrations. Comparison between morphological tissues of the sampled plants found that roots consistently presented higher metal concentrations than either the stems or leaves, however unlike previous studies, this investigation revealed no consistent trend of stems accumulating more metals than the leaves. For Typha spp., metal concentrations followed the order of roots > rhizomes > leaves, while for Persicaria spp. the order was roots > leaves > stems. The submerged species Myriophyllum aquaticum accumulated the highest levels of metals overall (e.g. Zn 4300 micrograms g-1 dry weight and Cd 6.5 micrograms g-1), and the emergent macrophytes also exhibited relatively high metal contents in their roots. The leaves of the submerged and floating-leafed species collected contained relatively high quantities of the four metals of interest, compared with the leaves of emergent aquatic macrophytes. In the Typha rhizome and Persicaria stem samples analysed for internal variation in metal content, there was a pattern of increasing metal concentrations towards the external sections of the stem, both for subterranean stems (rhizomes) and above-substrate stems. For Persicaria stems, no clear pattern was observed for cadmium and lead, the two metals investigated that are not required by plants for survival.

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The concentrations of SOCs in leaves of an evergreen Australian native tree (Melaleuca leucadendra) and grass collected in Brisbane, Australia were determined. The concentrations of PCDD/Fs and PAHs in the leaf tissue were comparable to those reported for urbanised areas in other industrialised countries. A distinct difference in the compound profiles between the leaves of the two species was observed, with higher concentrations of the lower molecular mass PAHs and PCDD/Fs and lower concentrations of the higher molecular mass PAHs and PCDD/Fs in the Melaleuca leaves relative to the grass leaves. The interspecies differences are explained on the basis of the larger size of the lipophilic compartment (for compounds with low K(OA)) and the lower ratio of surface area to volume in the Melaleuca leaves.

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The internal lethal concentration (ILC) and internal lethal volume fraction (ILVF) of a series of chlorobenzenes with mosquito fish (Gambusia affinis) were measured by a semistatic test approach in closed jars. Their variation with exposure times were also investigated with different aqueous chemical concentrations and different exposure periods, the measured ILC values on wet weight and lipid weight bases ranged from 3-12 mmol kg-1 and 46-208 mmol kg-1 lipid, respectively. Measured ILVF values covered a range from 0.008-0.025 (L toxicant L-1 lipid). These values are consistent with those found in literature. Generally ILC and ILVF values decreased with increasing exposure time with rate constants ranging from 0.03 to 0.33 day-1 (wet and lipid weight) for ILC and 0.03 to 0.31 day-1 for ILVF.

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A new hypothesis, the funnel hypothesis, was derived to explain the variation in toxicity of equitoxic multicomponent mixtures of nonspecific toxicants (narcotics). The variation is explained in terms of the volumes associated with solute-solute and solute-solvent interactions. The hypothesis predicts that as the number of components in a mixture increases, the range of deviation from toxic additivity decreases. It also predicts that the toxicity of mixtures measured using biological endpoints that require high toxicant concentrations will deviate more from toxic additivity than endpoints that require low concentrations. Aquatic toxicity data for equitoxic mixtures of narcotic toxicants to a range of aquatic organisms compiled from the literature support the predictions of the funnel hypothesis.

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Superhydrophobic compounds (log K(ow) greater than 6) do not bioconcentrate as much as predicted from the extrapolation of linear relationships between the logarithms of the bioconcentration factor (KB) and the octan-1-ol/water partition coefficient (K(ow)) developed for compounds with log K(ow) from 2 to 6. Statistical analysis of the literature data on solubility in lipid for 79 hydrophobic compounds demonstrated a decrease in lipid solubility with increasing K(ow) values for superhydrophobic compounds. A similar, but more significant, relationship was obtained for the chlorinated hydrocarbons which closely corresponded with effectively the same relationship derived from fish bioconcentration data. As a result it is suggested that an important factor contributing to the lower than expected bioconcentration exhibited by superhydrophobic compounds is their relatively low solubility in lipid not reflected by the K(ow) value. It is suggested that lipid/water partition coefficients would provide more accurate descriptors of the bioconcentration process.

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The critical concentration and critical volume hypotheses for non-specific toxicity require the molar concentration (CC) and volume fraction (VF) of toxicant in target tissue to be constant. Thus these factors should be independent of the octanol-water partition coefficient (Kow) for individual compounds. CC and VF values were calculated based on acute sub-lethal, acute and chronic lethal toxicity data, Kow and pure component molar volume (MV) data. When these values were plotted against log Kow, the slopes of the regression equations were significantly different to zero but were not significantly different from each other. The observed slight increase in CC and VF with increasing log Kow was attributed predominantly, to the use of Kow values which overestimate the target tissue-water partition coefficient (Kow). An additional error associated with the volume fraction calculations was the use of the molar volume instead of partial molar volume. VF and CC values were calculated correcting for both these factors and regressed against log Kow. The resulting equation for VF had a gradient not significantly different from zero, while that for CC was, thus indicating the superiority of the critical volume hypothesis in modelling non-specific toxicity of individual compounds.

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The toxicities of selected oil shale components and of mixtures of these components to a mixed marine bacterial culture have been determined. The toxicities of mixtures whose components were members of the same homologous series were found to be additive. In all other cases, even when the compounds were as closely related as structural isomers, synergism was observed. Simple and multiple linear regression equations utilizing measures of toxicity and molecular descriptors were used successfully to predict the enhancement of toxicity due to interaction of components in mixtures regardless of the mode of interaction.

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The toxicity of 32 shale oil components to a mixed marine bacterial culture was assessed utilizing an acute static bioassay protocol. Structure-activity relationships were examined between toxicity and 39 physicochemical properties and molecular descriptors, many of which have not been previously utilized in quantitative structure-activity relationship (QSAR) research. The toxicity could be predicted with reasonable accuracy using simple linear regression equations. However, multiparametric linear regression (MLR) equations yielded improved correlation coefficients and predictive capabilities. Such equations allow the inclusion of two or more characteristics in one relationship. The best MLR equations combined carbon number and interatomic distance between the most positive and negative charges, solubility, the approximate sigma electron density, and a variety of other parameters. These multiparametric QSARs with high predictive capabilities require computer-generated data which may not be readily available. Other MLR equations combine parameters such as the octanol water partition coefficient and the specific molecular connectivity index. These latter equations have lower correlation coefficients and yet are probably of more practical use as the data required are readily available or can be calculated. The presented multiparametric QSARs are applicable within the log Kow range of 0.6 to 5.5.

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For the bioconcentration of hydrophobic chemicals by fish, relationships have been previously established between uptake rate constants (k1) and the octanol/water partition coefficient (Kow), and also between the clearance rate constant (k2) and Kow. These have been refined and extended on the basis of data for chlorinated hydrocarbons, and closely related compounds including polychlorinated dibenzodioxins, that covered a wider range of hydrophobicity (2.5 less than log Kow less than 9.5). This has allowed the development of new relationships between log Kow and various factors, including the bioconcentration factor (as log KB), equilibrium time (as log teq), and maximum biotic concentration (as log CB), which include extremely hydrophobic compounds previously not taken into account. The shape of the curves generated by these equations are in qualitative agreement with theoretical prediction and are described by polynomial expressions which are generally approximately linear over the more limited range of log Kow values used to develop previous relationships. The influences of factors such as hydrophobicity, aqueous solubility, molecular weight, lipid solubility, and also exposure time were considered. Decreasing lipid solubilities of extremely hydrophobic chemicals were found to result in increasing clearance rate constants, as well decreasing equilibrium times and bioconcentration factors.

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Previously published data on the accumulation of 15 chlorinated hydrocarbons from sediment by oligochaetes have been interpreted on the basis of bioconcentration from interstitial water. Calculation of the interstitial water concentration allowed determination of uptake and clearance rate constants together with bioconcentration factors (KB) for these compounds. These three factors each exhibited a systematic relationship to the octanol/water partition coefficient (KOW). The log KB versus log KOW relationship was roughly linear over the log KOW range from 4.4 to 6.4 and displayed an increasing nonlinear deviation for log KOW values greater than 6.4. These relationships are qualitatively similar to those established for other aquatic organisms where bioconcentration from water was the mechanism involved. This suggests that interstitial water may be the phase from which lipophilic compounds in sediment are bioconcentrated by oligochaetes. An expression relating the bioconcentration factor to the biotic concentration and various sediment characteristics has also been developed.

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With nondegradable, lipophilic compounds having log P values ranging from 2 to 6, direct linear relationships have been found between the logarithms of the equilibrium bioconcentration factors, and also reciprocal clearance rate constants, with log P for daphnids and molluscs. These relationships permit calculation of the times required for equilibrium and significant bioconcentration of lipophilic chemicals. Compared with fish, these time periods are successively shorter for molluscs, then daphnids. The equilibrium biotic concentration was found to decrease with increasing chemical hydrophobicity for both molluscs and daphnids. Also, new linear relationships between the logarithm of the bioconcentration factor and log P were found for compounds not attaining equilibrium within finite exposure times.

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