Rare earth mineral based adsorbent viz. lanthanum oxide was investigated for potential application in defluoridation of drinking water for isolated and rural communities. Results of batch experiments indicated about 90% removal in 30 min from a 4 mg L−1 synthetic fluoride solution. The effects of various parameters like contact time, pH, initial concentration, and sorbent dose on sorption efficiency were investigated. Adsorption efficiency was dependent on initial fluoride concentration and the sorption process followed BET model. Variation of pH up to 9.5 has insignificant effect on sorption and beyond a pH of 9.5, the effect was drastic. Among anions investigated, carbonates exhibited high detrimental effect on fluoride adsorption while anions like bicarbonates, chlorides, and sulfates did not seriously affect the process. Adsorbent showed negligible desorption of fluoride in distilled water. Alum was more effective regenerant than HCl and NaOH. Results of cyclic regeneration with alum indicated that the sorbent could be regenerated for ten cycles without significant loss of sorption capacity. Studies with upflow fixed-bed continuous flow columns indicated the usefulness of sorbent for fluoride removal in continuous flow process.

The environmental impacts of 16 different contaminants originating from the E18 Highway (17,510 annual average daily traffic) were studied over the initial months of the highway’s operational life. Investigative methods used included electrical resistivity surveying, water chemistry analyses, soil analyses, distribution modeling, and transportation modeling of contaminants. The study conclusively showed a year-round infiltration due to melting of the snowpack from road salt, and a strong preferential, anthropogenic pathway due to increased hydraulic conductivities of road construction materials relative to in situ soils. The resistivity surveys produced values well below the expected values for the highway materials, indicating increased ionic content within the unsaturated zone. Time lapse resistivity modeling showed a clear downwards spreading of contamination from the roadway to subsurface distances greater than 5 m. Elevated concentrations of nearly every studied contaminant relative to baseline values were observed, with many metal concentrations within the snow pack averaging values in excess of the Swedish Environmental Protection Agency’s groundwater limitations. Distribution modeling demonstrated a potential offset of peak values from the road surface due to plowing and splash transport processes, and indicated different distribution behavior during winter months than during summer months. One-dimensional transport modeling demonstrated the importance of adsorption and other retentive factors to the migration of contaminants to groundwater and provided an estimate for potential long-term contaminant concentrations.

Bacteria, actinomycetes, and fungi are the dominant components of the soil microflora, and some of their species can perform denitrification. The aim of this study was to investigate the interactions of three kinds of denitrifiers in mix-culturing systems. Three denitrifying strains, i.e., one bacterial strain (strain B5), one actinomycete strain (strain A2), and one fungal strain (strain F1), were isolated from a rice paddy soil. Denitrifier interactions were examined by analyzing the population dynamics and metabolic substance in the mix-culturing systems with two and three strains and by estimating the effects of cell-free culture filtrates on the strains. Results showed that the growth of B5 was enhanced by F1 and A2, respectively, and nitrate removal proportions in the culture systems increased from 52% (B5) to 64% (B5 + F1) and 67% (B5 + A2), and the nitrate removal was further enhanced in the three strain mix-culturing system (74%, A2 + F1 + B5). Strain B5 stimulated the cell growth of A2 directly and indirectly. The existence of A2 was lethal for cell growth of F1, while A2 was also suppressed by F1. The suppressive interaction reduced nitrate removal rates from the single systems of 12.8 (F1) and 11.5 mg L−1 day−1 (A2) to 8.75 mg L−1 day−1 (A2 + F1). Likewise, F1 was inhibited by B5. The results also showed that the cell-free culture filtrates of other strains suppressed the cell growth of B5 and F1, respectively, but enhanced the cell growth of A2. In addition to the direct effect of cell-free culture filtrates, other indirect relationships could affect the denitrifier spatial distributions and balance of the suppression or promotion effects, which were beneficial to maintain the microbial structure and function stability with a low nitrous oxide emission in the soil.

This paper examined the ability of honeycomb biomass (HC), a by-product of the honey industry, to remove Pb(II), Cd(II), Cu(II), and Ni(II) ions from aqueous solutions. The equilibrium adsorptive quantity was determined as a function of the solution pH, amount of biomass, contact time, and initial metal ion concentration in a batch biosorption technique. Biosorbent was characterized by Fourier transform infrared (FTIR), scanning electron microscopy with energy-dispersive X-ray, and X-ray diffraction studies. FTIR spectral analysis confirmed the coordination of metals with hydroxyl, carbonyl, and carboxyl functional groups present in the HC. The metals uptake by HC was rapid, and the equilibrium time was 40 min at constant temperature and pH. Sorption kinetics followed a nonlinear pseudo-second-order model. Isotherm experimental data were fitted to Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models in nonlinear forms. The mechanism of metal sorption by HC gave good fits for Langmuir model, and the affinity order of the biosorbent for four heavy metals was Pb(II)>Cd(II)>Cu(II)>Ni(II). The thermodynamic studies for the present biosorption process were performed by determining the values of ΔG°, ΔH°, and ΔS°, and it was observed that biosorption process is endothermic and spontaneous. This work provides an efficient and easily available environmental friendly honeycomb biomass as an attractive option for removing heavy metal ions from water and wastewater.

The presence of illicit drugs and their metabolites in surface waters has to be considered a new type of hazard, still unknown, for the aquatic ecosystem, due to the potent pharmacological activities of all the illicit drugs. Our research was therefore aimed at evaluating the impact of illicit drugs on the aquatic fauna, till now still undervalued. To this aim, we verified the ability of the European eel (Anguilla anguilla), a well-known biomonitor of environmental contamination, to bioaccumulate cocaine, one of the most abundant illicit drugs found in surface waters. Silver eels were exposed to a nominal cocaine concentration of 20 ng/l for 1 month; at the same time, control, carrier, and post-exposure recovery groups were made. Brains, gills, liver, kidney, muscle, gonads, spleen, digestive tract, and sections of dorsal skin were assayed by high-pressure liquid chromatography. Cocaine was found in the tissues of the treated eels and, at low concentrations, in almost all tissues of post-exposure recovery eels. These results indicate that cocaine is able to accumulate into the eel tissues; its presence suggests potential risks for eels since cocaine could affect their physiology and contribute to their decline, and for humans consuming contaminated fish.

Paracetamol is an antipyretic analgesic widely used globally. It has been recurrently found in water bodies and is known to elicit toxic effects in aquatic species; however, its potential ability to induce oxidative stress in sentinel species remains unknown The objective was to establish a methodology to evaluate the toxicity elicited on the sentinel species Hyalella azteca by paracetamol-enriched sediment using oxidative stress tests. Concentrations used in assays were determined using the previously obtained median lethal concentration (72 h LC₅₀). The following oxidative stress biomarkers were evaluated: lipid peroxidation (LPO), protein carbonyl content (PCC) in order to determine oxidized protein content, and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). LPO and PCC increased significantly while SOD, CAT, and GPX decreased significantly (p < 0.05) with respect to controls. Paracetamol induces oxidative stress on H. azteca, and the set of tests employed is helpful in evaluating the toxicity of this group of pharmaceuticals on aquatic species.

Metal contamination of freshwater bodies resulting from mining activities or deactivated mines is a common problem worldwide such as in Portugal. Braçal (galena ore) and Palhal (pyrrhotite, chalcopyrite, galena, sphalerite, and pyrite ore), located in a riverside position, are both examples of deactivated mining areas lacking implemented recovery plans since their shutdown in the early mid-1900s. In both mining areas, effluents still flow into two rivers. The purpose of this work was to evaluate the potential hazard posed by the mining effluents to freshwater communities. Therefore, short- and long-term ecotoxicological tests were performed on elutriates from river sediments collected at each site using standard test organisms that cover different functional levels (Vibrio fischeri, Pseudokirchneriella subcapitata, Lemna minor, and Daphnia sp.). The results show that elutriates from the sediments of Palhal were very toxic to all tested species, while in contrast, elutriates from Braçal showed generally no toxicity for the tested species. Our study highlights the usefulness of using an ecotoxicological approach to help in the prioritization/scoring of the most critical areas impacted by deactivated mines. This ecotoxicological test battery can provide important information about the ecological status of each concerning site before investing in the application of time-consuming and costly methods defined by the Water Framework Directive or can stand as a meaningful complementary analysis.

In aquafarming, 17α-methyltestosterone (MT) is widely used as an anabolic steroid to induce the sex of Nile tilapia fry to male in order to increase production yield. Nile tilapia fry is fed at a rate of 0.06 mg of MT/kg of feed during the first 21 days after hatching. MT not consumed by the fish fry may be sorbed onto the sediment in the fish ponds which may contaminate the environment when released from the ponds. Using soils and sediment from a Nile tilapia masculinization pond as sorbents in batch sorption experiments, the linear sorption coefficients (K d) of MT were found to range from 1.2 to 168.8 L/kg with an average K ₒc value of 9,450 L/kg. The linear sorption coefficients of MT were found to correlate with the organic carbon contents of the sorbents. Sorption of MT onto sand, garden soil, and sediment was not impacted by pH, but the sorption of MT onto sediment was found to be impacted by the salinity of the water. The salting out coefficient of MT in saline water was found to be approximately 0.87 L/mol.

Mercury bioaccumulation kinetics of two important macrobenthic species, the polychaete Hediste diversicolor and the bivalve Scrobicularia plana, were evaluated following a dietary pathway (i.e. contaminated algae), through a mesocosm laboratory experiment. Both studied species presented a similar model of Hg bioaccumulation kinetics, a linear pattern of accumulation through time being the mercury accumulation in the organisms proportional to the mercury concentration in the food. Mercury bioaccumulation rates were higher in the polychaete H. diversicolor (reaching approximately 0.15 μg g−1 at the end of the experiment) than in the bivalve S. plana (≈0.07 μg g−1), which could be related to their feeding strategies, ingestion rates and assimilation efficiencies. Moreover, the mercury bioaccumulation revealed to be quite a fast process especially for the polychaete, and despite the fact that this species is not an edible organism, it is an important prey item, which can greatly contribute to the transport of contaminants to higher trophic levels. Therefore, the bioaccumulation of mercury by these important macrobenthic species, especially the bivalves, represents a non-negligible risk for humans.

The aim of this work has been to analyze the effects of a bioemulsificant exopolysaccharide (EPS₂₀₀₃) on the abundance and vitality of natural marine microbial population. Harbor seawater microcosms, supplemented with bioemulsificant EPS₂₀₀₃ (at different concentrations), were monitored over 20 days. The microbial community dynamic was analyzed by measurement of bacterial density (total and cultivable count) and vitality (live/dead count and total RNA amount). The results obtained show that addition of bioemulsificant (also at different concentrations), as sole carbon source, supported growth of the indigenous bacterial populations and revealed that this substance is optimal for use in the participations of recovery of environment polluted from oil. In comparison, an analysis with commercial dispersant was also carried out.