Concentration of methylmercury (MeHg) in different habitats and associated food chains may vary because of habitat characteristics that determine methylation and MeHg transfer. We examined MeHg levels in primary consumers from littoral, pelagial and profundal habitats of a boreal humic lake, and measured total mercury (TotHg) and MeHg in surface sediments at increasing depths. MeHg concentrations in primary consumers increased from profundal to littoral, a pattern which was mirrored by the surface sediment concentrations. Methylation potential (expressed as the ratio of MeHg to TotHg) was lower in profundal than in littoral sediments, suggesting that littoral sediments have higher net methylation rates. No specific MeHg-enriched entrance point in the littoral food chain was identified, however. High MeHg concentrations in littoral primary consumers and sediments suggest that shallow lake sediments are important for MeHg transfer to the aquatic food web in boreal humic lakes. Lake morphometry, most specifically the fraction of littoral, is hence likely to add to differences in MeHg bioaccumulation rates in lake food webs.

The textile industry often releases effluents into the environment without proper treatment or complete dye removal. Azo dyes, which are characterized by azo groups (―N═N―), are frequently used in the textile industry. Among the different wastewater treatment methods available, biological treatment has been extensively studied. The aim of the present study was to compare the biodegradation of the azo dye Direct Blue 71 by the fungi Phanerochaete chrysosporium and Aspergillus oryzae in paramorphogenic form using a 100 μg/ml dye solution. Biodegradation tests were performed within 240 h. The absorbance values obtained with UV-VIS spectrophotometry were used to determine the absorbance ratio and the percentage of dye discoloration following the biodegradation test. FTIR analysis allowed the identification of molecular compounds in the solution before and after biodegradation. Both A. oryzae and P. chrysosporium demonstrated considerable potential regarding the biodegradation of dyes in wastewater. These results may contribute toward improving effluent treatment systems in the textile industry.

In this work, a mesoporous carbon material was modified by nitrogen atom by two different ways. The X-ray photoelectron spectroscopy (XPS) results show that the N atoms at the surface mainly exist in pyridine- and pyridone-like forms (around 80 % in atom ratio). The adsorption capacity of phenol and nicotine on mesoporous carbon and two N-containing mesoporous carbons was studied through adsorption isotherms. The adsorption isotherms were interpreted by three models (Freundlich, Langmuir, and Sips equations). Heat-flow microcalorimetry in liquid phase was used to determine the bonding strength between the organic pollutants and the surface of the adsorbents. In addition, the possibility of regeneration of adsorbents was investigated by temperature-programmed desorption (TPD) technique. The obtained values of differential heats and isotherms showed the heterogeneous properties of the mesoporous carbon materials. Comparing the different results obtained from the experiments, the surface area is a key factor for the adsorption of phenol and nicotine in water. The introduction of N improved the adsorption of phenol but did not affect the adsorption of nicotine.

A simple, rapid, sensitive, and inexpensive dispersive liquid–liquid microextraction method was developed for the determination of trace amounts of copper by flame atomic absorption spectrometry (FAAS). N,N′-bis-(2-hydroxy-5-bromobenzyl)-2-hydroxy-1,3-diiminopropane was used as the chelating ligand. Several analytical parameters affecting the microextraction efficiency such as, sample pH, volume of extraction solvent (carbon tetrachloride), concentrations of the chelating ligand and NaCl, and sample volume were investigated and optimized. The effect of the interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.75 μg L⁻¹for copper with a sample volume of 10 mL, and a preconcentration factor of 20 was achieved. The relative standard deviation (R.S.D) for ten independent determinations of a 10 μg L⁻¹solution of Cu(II) was 2.3 %. In order to verify the accuracy of the developed method, different certified reference materials (SLRS-5, QCS-19, Rice flour unpolished high level of Cd NIES 10c) were analyzed and the results obtained were in good agreement with the certified values. The proposed method was applied to tap water, river water, seawater, rice flour, and wheat flour samples. The percentage recovery values for spiked water samples were between 95.4 and 108.4.

The potential for bioremediation of chromium pollution using bacteria was investigated in this study. Five chromium-removing bacteria strains were successfully isolated from Cr(VI)contaminated soils and identified by their 16S rRNA gene sequences. The optimum growth temperature (30–40 °C) and pH (8.5–11) for the five isolates were investigated. The effect of initial Cr(VI) concentrations (0–1,575 mg L⁻¹) on bacterial growth was also studied. Results showed that Pseudochrobactrum saccharolyticum strain W1 had high chromium-removing ability and could grow at Cr(VI) concentrations from 0 to 1,225 mg L⁻¹. To our knowledge, this is the first report of chromium removal by a member of the Pseudochrobactrum genus. Sporosarcina saromensis W5 had the highest chromium-removing rate of 0.79 mg h⁻¹ mg⁻¹biomass. Exopolysaccharide (EPS) production and components of the five bacteria strains were also investigated, and a positive relationship was found between the bacterial chromium removal and EPS production.

The relationship between ambient concentrations of fine particulate matter (PM2.5) and detrimental effects on fauna remains a highly controversial issue. The present study has determined the levels of fine particulate matter and trace metals in the particulate matter as well as in soil and plants in an oil field of Assam in northeastern India in order to assess the effects of oil exploration on muga (Antheraea assama) silk worms. Ambient PM2.5 concentration was monitored daily at two sites during November (one of the driest months) along with the trace metals, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn. The distance variation of the trace metals was determined by factors related to dispersion and the emission sources. Higher levels of PM2.5 were measured during the night. This might be due to increased emissions from the group gathering station of crude oil done during the night. Significant correlations were observed among the trace metal compositions of the fine particulate matter in ambient air, soil, and plants of the oil field area, and the same were related to the oil exploration activities. Meteorological data and statistical analysis further confirmed the influence of the oil field activities on the levels of PM2.5 and the trace metals.

The growing demand for new sources of water for irrigation has led to an increase in the practice of using treated wastewater in agricultural processes. Thus, in the present research, we have assessed the irrigation of a culture of eucalyptus with reclaimed wastewater. The sewage comes from domestic sources and was treated in a facultative lagoon. The culture of eucalyptus was assessed through plant diameter at breast height and total volume of wood produced. Soil contamination was determined through its salinization and the values of sodium adsorption ratio (SAR). The use of wastewater in irrigation has brought an increase of 82.9 % in productivity compared to traditional cultivation. This shows that in a same area of cultivation, practically double of the eucalyptus wood could be obtained and used in the most different industrial activities. In addition, it would prevent the entering of a large amount of nutrients in water bodies due to their recycling in the agricultural culture. In the period of 4 years of studies, SAR has always been below the values pointed by the literature as indicators of problems for the soil.

The simultaneous removal of phenol and ammonium using heterotrophic nitrifying-denitrifying bacterium Serratia sp. LJ-1 was investigated. The maximum removal rates of ammonium nitrogen and phenol were 1.08 ± 0.05 and 2.14 ± 0.08 mg L⁻¹ h⁻¹, respectively. The ammonium oxidation had much higher tolerance to phenol toxicity than that of the autotrophic nitrifying bacteria. The increase in phenol concentration led to an increase in ammonium oxidation rate under the phenol concentration of 600 mg L⁻¹. The increase in ammonium concentration caused an increase in phenol biodegradation rate under the ammonium nitrogen concentration of 150 mg L⁻¹. Maximum rates of phenol biodegradation and total nitrogen removal in the treatments with nitrification metabolite (nitrate or nitrite) as the sole nitrogen source were more than 30 % lower than those of the treatment with ammonium as the sole nitrogen source. Ammonium was removed through nitrification and subsequent aerobic denitrification while phenol was biodegraded through the ortho-cleavage pathway and subsequently mineralized. Since phenol often coexists with nitrogen pollutants, these findings have significant environmental implications in terms of the simultaneous removal of these contaminants.

The leachate pollution index (LPI) represents a tool to assess the pollution potential of a leachate, on a scale from 5 to 100. However, the significance of the LPI number in terms of a particular phytotoxic effect has not been investigated. The aim of this work was to determine if the LPI is also an appropriate tool in relation to the biological significance of a phytotoxic assay using the common bean plant (Phaseolus vulgaris L.) in a greenhouse scale test. Two different leachates were used in this study: one from Guanajuato (GUL) and another from Toluca (TOL); the calculated LPIs were 34.8 and 18.4, respectively. Leachate dilutions of 25, 50, and 75 % were used; undiluted leachate (100 %) was also used, and an enriched mineral solution was used as the control. Our findings indicate that when using concentrated leachate, the LPI was not directly related to the recorded phytotoxic effect (grain yield was significantly reduced by TOL leachate); however, when only using diluted leachate (25 %), the LPI was directly related to the effect. These findings suggest that for diluted leachates, leachates with higher LPIs are likely to exert a more detrimental effect on the common bean than leachates with lower LPIs.

Analytical method for the determination of six flame retardants (FRs) from two groups was proposed. These groups included the brominated flame retardants (BFRs) 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and tetrabromophthalic anhydride (TBPA) and triester organophosphate flame retardants (OPFRs) tris(2,3-dibromopropyl) phosphate (TBPP), ethylhexyl diphenyl phosphate (EHDP) and triphenyl phosphate (TPhP). Reversed phase ultrahigh-performance liquid chromatography (UHPLC) with a UV detector, different chromatographic columns, different mobile phases and gradient elution programmes were used to obtain the best separations within the shortest possible time. Solid-phase extraction (SPE) was examined as a pre-concentration step from distilled water. The column with the highest recoveries (the Bond Elut ENV column gave recoveries over 70 % for all compounds) was then tested on 1-L blank surface water samples. The proposed analytical procedure was applied for the determination of FRs in surface water samples. The concentrations of FRs found in water samples ranged from 0.03 (TPhP) to 3.10 μg L⁻¹(HBCD). Method detection limits (MDLs) ranged from 0.008 to 0.518 μg L⁻¹, and method quantification limits (MQLs) ranged from 0.023 to 1.555 μg L⁻¹for all compounds.