This paper examined the gut digestive enzymes, trypsin and leucine aminopeptidase (LAP), in gypsy moth (Lymantria dispar, L.) larvae exposed to cadmium. We analyzed the 3-day acute effect, chronic effects from hatching until sacrifice, and recovery from long-term dietary treatment with cadmium concentrations of 10 and 30 μg Cd/g dry food. The activities of both examined enzymes declined at the higher level of cadmium after both acute and chronic treatments and did not recover within 3 days of feeding a diet with no added cadmium. Leucine aminopeptidase was more sensitive because its activity was inhibited after both short-term treatments. Three trypsin and one leucine aminopeptidase isoform were detected by electrophoresis. Egg hatches (full-sib families) differed in enzyme activities, index of phenotypic plasticity, and isozyme expression after different treatments. Statistically significant positive correlations between these enzymes pointed to common genetic regulation. Moreover, variances were higher for the control group than for cadmium treatment groups implying that these proteolytic enzymes did not participate directly in detoxification. These results suggest that, with additional research to discover the mechanisms of enzyme inhibition, trypsin and leucine aminopeptidase might be used as biomarkers to indicate the severity of gastrointestinal disease due to cadmium intake.

Electric arc furnace (EAF) dust and slag, materials which contain high metals in their composition, were improperly disposed in an industrial steel mill site between 1963 and 1999. Previous environmental investigations identified anomalous concentrations of metals in local groundwater but failed to relate these abnormalities to the disposed material or to natural geochemical processes. Aiming to identify the origin of such abnormalities, exploratory and spatial data analysis (EDA-SDA) method was applied on a hydrogeochemical data set obtained through 5 sampling campaigns in 32 groundwater monitoring wells installed upstream and downstream of the area impacted by the steel mill activities. Boxplot class-based and Eh vs. pH maps of physicochemical log-transformed data identified that wells located under the influence of EAF slag deposits in topographic hollows had lower Eh potential and increased electrical conductivity and pH, when compared to wells in the topographical nose of the surveyed area. Metal distribution maps showed that Al, Ca, K, Mg, Na, and Sr were consistently higher in topographic hollows while concentrations of Co, Cu, Cr, and Li were higher near the former steel-making plant, located in the topographical nose. Ba, Fe, Mn, and Zn, important indicators of EAF slag and dust, were observed in both topographic settings. Variable clustering was able to capture the relations among metals and thus validate the log-normalized data structure to be used into wells clustering. Clustering through the mclust algorithm carried out for two and three clusters allowed the distinction among localities that received an input of metals from dust or slag and those not influenced by either residue. This paper demonstrates that EDA-SDA is an effective method to identify areas under the influence of contamination from industrial activities from areas not affected by anthropogenic contamination.

Dichlorodiphenyltrichloroethane (DDT) is one of the persistent organic pollutants (POPs) that are highly toxic to the environment. Effective evaluation on the bioavailability of DDTs in soils is essential for risk assessment and soil remediation. The aims of this study were to verify the feasibility of the hydroxypropyl-β-cyclodextrin (HPCD) extraction method for predicting the bioavailability of DDT, dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE) in soils, and to examine the effect of HPCD on their biodegradation in different soils. Four soils were aged with a mixture of p,p′-DDT, o,p′-DDT, p,p′-DDD and p,p′-DDE (0.25 μg g⁻¹ for each compound) for 20 and 100 days, respectively. For each of the DDTs, a significant positive correlation between HPCD-extractable fraction and biodegradable fraction in each soil was observed. It was demonstrated that the amounts of HPCD-extractable p,p′-DDT and o,p′-DDT were not significantly different from the amounts that were degradable as assessed from their degradation by Enterobacter sp. LY402 (p > 0.05). Such 1:1 relationship between extraction and degradation was not obtained in the cases of p,p′-DDD and p,p′-DDE, as the amounts of degradable p,p′-DDD and p,p′-DDE were lower than the amounts that were extractable with HPCD. Additionally, the biodegradation of p,p′-DDT, o,p′-DDT, p,p′-DDD, and p,p′-DDE was inhibited in the presence of HPCD, which could be due to the binding of the compounds to HPCD, making them less available to access the bacteria for degradation. This study provides the possibility of using the HPCD extraction method to predict the bioavailability of p,p′-DDT and o,p′-DDT in soils. But when HPCD was used as an additive in the bioremediation of DDT-contaminated soils, it might have a negative effect on biodegradation.

Advanced wastewater treatment with granular activated carbon (GAC) is a promising option to reduce emissions of organic micropollutants (OMP) into the aquatic environment. Frequent back-washes of the GAC filters are required due to high particle concentration in the treated wastewater but lead to stratification. Differences in adsorption capacities of individual strata are not known. The present study aimed at investigating physical and chemical differences at different filter depths of a stratified GAC filter. Two different commercial products were stratified during repeated filter bed expansions and sectioned into vertical fractions. Bulk densities, grain size distributions and ash contents of the individual fractions differed significantly. Adsorption tests with pulverized GAC from different levels showed great vertical differences in adsorption properties. OMP removals determined in the upper part of a GAC filter therefore cannot be extrapolated downwards. Both physical and chemical vertical heterogeneities with regard to adsorption capacities and residence times at different filter depths should be considered in the filter design, in the monitoring of a GAC filter, and in the interpretation of the GAC filter performance. Good correlations between abatements of UV light absorption and OMP removals were found for the virgin GAC throughout the non-uniform filter.

In this work, the removal of methylene blue by Bacillus thuringiensis (Bt) 016 was investigated through batch experiments and microscopic investigations. It was found that methylene blue could not affect the growth of B. thuringiensis 016 at the concentration ranging from 5 to 25 mg/L, and be removed with the increase of biomass. Further studies indicated that Bt 016 biomass possessed strong ability of methylene blue biosorption with a quick process. Twenty-five milligrams of methylene blue per liter could be completely biosorbed within 2 h. The pH value could affect the removal of methylene blue in a large extent. UV–visible, Fourier transform infrared (FT-IR) spectroscopy analyses, and microscopic investigations suggested that the removal of methylene blue could be divided into two steps as follows: (1) rapid biosorption of methylene blue on Bt 016 biomass through electrostatic attraction or chelating activity of functional groups; (2) methylene blue was further degraded by Bt 016 through enzyme-mediated or couple with the metabolism process.

Shewanella putrefaciens IBBPₒ₆(KM405339) showed good tolerance to 5 % organic solvents. The growth was higher when S. putrefaciens IBBPₒ₆cells were exposed to n-decane, as compared with the growth of cells exposed to toluene, o-xylene, ethylbenzene, cyclohexane, or n-hexane. Thus, n-decane was less toxic for S. putrefaciens IBBPₒ₆cells, while toluene, o-xylene, ethylbenzene, cyclohexane, and n-hexane were more toxic for this bacterium. The release of nucleic acids was higher when S. putrefaciens IBBPₒ₆cells were exposed to toluene, o-xylene, ethylbenzene, cyclohexane, or n-hexane, as compared with the release of nucleic acids from control cells and n-decane exposed cells. The cell surface hydrophobicity increased when S. putrefaciens IBBPₒ₆cells were exposed to n-decane, while in the presence of toluene, o-xylene, ethylbenzene, cyclohexane, and n-hexane, a decrease in the cell surface hydrophobicity was acquired. The exposure of S. putrefaciens IBBPₒ₆cells to 5 % organic solvents had induced biofilms formation, and their structure differs according to the nature of the hydrophobic substrate. Two secondary metabolites (i.e., biosurfactants, carotenoids) were produced by S. putrefaciens IBBPₒ₆control cells, as well as by the cells exposed to 5 % organic solvents. S. putrefaciens IBBPₒ₆possesses alkB1 and alkM1 catabolic genes and HAE1 transporter gene. A homologue of otsA1 gene was also detected in this bacterium. Some differences between the polymerase chain reaction (PCR) patterns of S. putrefaciens IBBPₒ₆control cells and cells exposed to 5 % organic solvents were observed. Distinct repetitive sequence-based PCR (rep-PCR), random amplification of DNA fragments (RAPD), and amplified ribosomal DNA restriction analysis (ARDRA) patterns were also acquired in S. putrefaciens IBBPₒ₆cells exposed to 5 % organic solvents, compared with the control cells.

In this study, various metal concentrations were determined in environmental samples from rivers in the vicinity of mining areas of the Northwest Province, South Africa. These metal concentrations were also determined in various crustacean organs viz., hepatopancreas, flesh and muscle of the freshwater crab, Potamonautes warreni. The highest metal concentrations obtained in the freshwater samples were Ni (0.022 mg/l), Pb (0.02 mg/l), Cu (0.011 mg/l), Cd (0.009 mg/l), Pt (0.017 μg/l), Pd (0.011 μg/l) and Rh (0.008 μg/l). The highest metal concentrations obtained in the sediment samples were Ni (85.1 mg/kg dry weight (d.wt)), Pb (25.4 mg/kg d.wt), Cu (75.5 mg/kg d.wt), Cd (64.9 mg/kg d.wt), Pt (0.38 ng/g d.wt), Pd (0.74 ng/g d.wt) and Rh (0.23 ng/g d.wt). The results obtained for the bioavailability studies of all the metals investigated in the sediment have revealed no definite patterns for the fractionation results of the metal concentrations. In the case of the crab samples collected in the Elands River, the Pb, Cd, Pt, Pd and Rh concentrations indicate that the mining activities may have had an influence in the uptake of these metals in the crab samples analysed. In the case of the Hex River, the Ni, Cu, Pb, Cd, Pd and Rh concentrations in the crab samples may be attributed to mining activities. The bioaccumulation results indicated that the Ni and Cu concentrations show partly bioaccumulation in the tissues of the crab samples evaluated. For the Pd, Cd, Pt, Pd and Rh concentrations evaluated, definite signs of bioaccumulation were found.

A novel magnetic pyridinium-functionalized mesoporous silica adsorbent (Fe₃O₄@SiO₂@Py-Cl) was synthesized for nitrate removal from aqueous solutions. The adsorption performances were investigated by varying experimental conditions such as pH, contact time, and initial concentration. The adsorbent was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and magnetic hysteresis loops. The results showed that the adsorption equilibrium could be reached within 30 min and the kinetic data were fitted well by pseudo-second-order and intra-particle diffusion model. The adsorbent exhibited a favorable performance, and its maximum adsorption capacity calculated by the Langmuir isotherm model was 1.755 mmol/g. The nitrate adsorption mechanism was mainly controlled by the material through ion exchange of nitrate with chloridion, as determined by XPS. This study indicated that this novel pyridinium-functionalized mesoporous material had excellent adsorption capacity. Meanwhile, compared with other adsorbents, it could remove nitrate fast and easy to be collected by magnetic separation, showing great potential application for nitrate removal from aqueous solution.