Currently, there are large areas of soils contaminated with hexachlorocyclohexane (HCH) isomers which are included in the group of persistent organic pollutants. For the bioremediation of such soils, a new HCH-degrading Rhodococcus wratislaviensis strain Ch628 was isolated from long-term organochlorine contaminated soils. The strain Ch628 was able to degrade 32.3% γ-hexachlorocyclohexane (γ-HCH/lindane), 25.2% hexachlorobenzene, and 100% chlorobenzene in resting cell conditions. The strain Ch628 was bioaugmented in chronically HCH-contaminated soil. The results showed that the bioaugmentation of contaminated soil with the strain Ch628 led to HCH degradation. In the bioaugmented system, the efficiency of HCH removal at the initial concentration of about 238.7 ± 4.9 mg kg⁻¹ soil was 44.8%, while the system with indigenous microflora (without R. wratislaviensis strain Ch628) and the system with abiotic control removed 33.3 and 16.4% of this compound during the same period, respectively. Strain Ch628 could effectively degrade α-, β-, and γ-isomers of HCH (77.1, 100, and 100%, respectively) and heptachlorocyclohexane (69.9%) in the model soil systems. Moreover, the bioaugmentation with the strain Ch628 led to degradation of tri-, tetra-, and penta-chlorobenzenes, which are of HCH degradation metabolites. For the first time, it was found that the bioaugmentation with the bacterial strain Rhodococcus wratislaviensis Сh628 led to a significant reduction of the toxicity of the HCH-contaminated soil for the test organisms, such as Chlorella vulgaris Beijer and Daphnia magna Straus.

Antibiotics are often misused or overused, resulting in large residue inputs in the environment. Electricity and antibiotics were regarded as potentially important factors, which impact on the microbial community during treatment of antibiotics in three-dimensional biofilm-electrode reactors (3D-BERs). Unfortunately, only a few studies have been reported yet. Four 3D-BERs and one 3D-BR (reactor with biological sludge and no voltage) were designed to assess the effect of low current, sulfamethoxazole (SMX), and tetracycline (TC) on microbial populations. The 3D-BERs achieved excellent removal efficiencies of 72.20–93.52 and 82.61–95.80% for SMX and TC, respectively. Microorganisms were classified into 58 phyla, 125 classes, 166 orders, 187 families, and 220 genera. Proteobacteria held the overwhelming predominance, followed by Bacteroidetes, Chloroflexi, Actinobacteria, Verrucomicrobia, Firmicutes, and Acidobacteria. The 3D-BERs achieved higher richness of microbial composition compared with the 3D-BR. Microbial communities and relative abundance at the phyla level were affected by low current. The microbial communities in the 3D-BERs were similar at the genus level, even with different antibiotic concentrations. However, the relative abundances and compositions of the microbial communities decreased during the treatment of antibiotics. To increase the performance of 3D-BERs, the function of microorganisms should be investigated in future studies.

Bisphenol A (BPA), a well-known endocrine-disrupting chemical, is receiving increasing concerns regarding its adverse effects on the endocrine system in wildlife and humans. This study was designed to investigate BPA pollution in environmental media in plastics industry areas and to explore the relationship between BPA pollution and the characteristic of different plastics industry. A total of 66 river water samples, 6 aquatic animal samples, and 64 surface soil samples were collected from three cities with different characteristics of plastics industry in southeast China. BPA concentrations in river water (240–5680 ng L⁻¹), aquatic animals (116.13–477.42 ng g⁻¹), and surface soil (38.70–2960.86 ng g⁻¹) were highest in Yuyao City where the plastics industry mainly involved in the production of plastic raw materials. BPA concentrations in Taizhou City were modest and comparable to those reported elsewhere though Taizhou is characterized by its massive production of plastic products. BPA concentrations in Wenzhou City were the lowest where relatively low activities are involved in the plastics industry. Our data indicate that the plastics industry involved the use of BPA as an intermediate in production of raw plastics such as polycarbonate plastics and epoxy resins was the dominant cause of BPA pollution in the surrounding environments. Graphical Abstract Production of raw plastic is the dominant cause of BPA pollution in the environment

Activated carbon-coated electrode was developed and applied in electrostatic precipitator to remove volatile organic compound gases simultaneously with dust particles from a contaminated air. The activated carbon coating mixture was made up of powdered activated carbon (AC), carbon black (CB), and polyvinyl acetate (PVA), and methanol was added as a solvent to control the thickness of the mixture for best coating performance. During the coating process, the Brunauer-Emmett-Teller (BET) surface decreased to 86% of the original AC while pore volume percentages of macro pore increased, compared to micro- and meso-sized pores. The adsorption isotherm of benzene, toluene, ethyl benzene, and xylene (BTEX) gases onto the original AC and AC coating mixture (AC thoroughly mixed with PVA and methanol for coating and powdered again after dry) were tested and compared to each other, and it was found that both isotherm were best fitted to Freundlich and Langmuir isotherm with the order of adsorption capacities; ethyl benzene > m-xylene > toluene > benzene. The difference between adsorption capacities was clearer with the absorbent AC but became little with the AC coating mixture. In removing BTEX at increasing linear velocities up to 6.7 cm/s, it appeared that the surface area of AC electrode was directly proportional to its removal rate of BTEX. The thermal desorption was applied to regenerate the AC electrode, and 200 °C was found to be most efficient for benzene desorption, but higher temperature would be required for entire BTEX gases desorption.

The widespread use of unconventional drilling involving hydraulic fracturing (“fracking”) has allowed for increased oil-and-gas extraction, produced water generation, and subsequent spills of produced water in Colorado and elsewhere. Produced water contains BTEX (benzene, toluene, ethylbenzene, xylene) and naphthalene, all of which are known to induce varying levels of toxicity upon exposure. When spilled, these contaminants can migrate through the soil and contaminant groundwater. This research modeled the solute transport of BTEX and naphthalene for a range of spill sizes on contrasting soils overlying groundwater at different depths. The results showed that benzene and toluene were expected to reach human health relevant concentration in groundwater because of their high concentrations in produced water, relatively low solid/liquid partition coefficient and low EPA drinking water limits for these contaminants. Peak groundwater concentrations were higher and were reached more rapidly in coarser textured soil. Risk categories of “low,” “medium,” and “high” were established by dividing the EPA drinking water limit for each contaminant into sequential thirds and modeled scenarios were classified into such categories. A quick reference guide was created that allows the user to input specific variables about an area of interest to evaluate that site’s risk of groundwater contamination in the event of a produced water spill. A large fraction of produced water spills occur at hydraulic-fracturing well pads; thus, the results of this research suggest that the surface area selected for a hydraulic-fracturing site should exclude or require extra precaution when considering areas with shallow aquifers and coarsely textured soils.

Mercury (Hg) speciation and bioavailability were studied in surface water, surface sediment and freshwater fish samples collected upstream and downstream of the Medupi (currently under construction) and Matimba power stations in the Waterberg area, Limpopo Province. The initial survey was conducted in May 2010 and continued periodically/seasonally until October 2014. This study was designed to provide an overall description of the levels of Hg in areas potentially impacted by emissions from the coal-fired power station and provide the necessary information to enhance the understanding of the factors regulating the fate and transport of Hg in the environment. Percent loss on ignition (LOI) and ancillary water quality measurements were also carried out. In this study, the total mercury (TotHg) concentrations ranged between 0.92 and 29.13 ng/L, and 0.13 and 8.00 ng/L for methylmercury (MeHg) in water. Total Hg concentrations ranged between 0.50 and 28.60 ng/g, while the MeHg concentration ranged between 0.08 and 2.22 ng/g in sediments. Mercury concentrations in fish ranged between 40 and 1200 ng/g for TotHg, and 13.42 and 600 ng/g for MeHg. Methylmercury concentrations in freshwater fish sampled exceeded the United States Environmental Protection Agency criteria (300 ng/g) in 10% of the total fish sampled and 5% exceeded the WHO guideline (500 ng/g).

Although there is a growing interest in emerging organic contaminants (EOCs), most research is focused on wastewater treatment, the occurrence of EOCs, and their fate in the aquatic environment. There is limited information about their behavior in agricultural soils, where they can be introduced via irrigation with treated wastewater (TWW). In this study, the degradation in an agricultural soil of eight EOCs (bisphenol A, carbamazepine, diethyl phthalate, ethyl paraben, 5-methyl-1H-benzotriazole, primidone, Surfynol 104, and tris(2-chloroethyl) phosphate) with a broad range of physical-chemical properties was monitored for 40 days. Two types of soil treatments were performed: non-sterilization and sterilization. In the non-sterilized soil, by the end of the incubation period, degradation was greater than 70% for all the target compounds except carbamazepine, Surfynol 104, and primidone (<50%). In contrast, in the sterilized soil, the degradation of most of the compounds was less than 50%, except ethyl paraben, 5-methyl-1H-benzotriazole, and diethyl phthalate (>70%). These findings indicate that soil sterilization reduces overall degradation rates, which suggests that microbial activity plays an important role in the degradation of most of the EOCs studied in soil.

Although differential sensitivity of lichens to calcium excess has been documented previously at the community level, ecophysiological studies, which would shed light on the calcifuge or calcicole nature of lichens, are virtually absent. In the present study, we compared physiological responses of two morphologically similar foliose lichens, Dermatocarpon miniatum (calcicole lichen) and Umbilicaria hirsuta (calcifuge lichen) to Ca excess (up to 100 mM). The degree of total Ca uptake by the lichens after 24-h prolonged exposure was compared with selected physiological markers including levels of assimilation pigments, chlorophyll a fluorescence, soluble proteins, ergosterol, TBARS, and hydrogen peroxide. Both tested lichens accumulated Ca from the applied solutes of CaCl₂ by a dose-dependent manner, although excess of Ca did not change content of assimilation pigments in both tested lichens, as well as integrity of lichen symbiont membranes (tested as TBARS, K content, and ergosterol content) when compared to respective controls. However, we observed significant, concentration-dependent decrease of chlorophyll a fluorescence, content of soluble proteins, and hydrogen peroxide production in U. hirsuta, while in D. miniatum were all these parameters stable through all tested Ca concentrations.

Organic matter and nutrient in pig manure were treated using an integrated filter system. The influent flowed into an anaerobic filter (AF), and the AF effluent was polished in a biological aerated filter (BAF). The filter system was operated with recirculation ratios of 1–3. The filter system was operated with two recirculation methods. When a filter system was operated under bottom recirculation conditions, the nitrated effluent from the BAF was mingled with the influent in the AF. For upper recirculation conditions, the nitrated effluent from the BAF was injected into a height of 36% from the bottom in the AF. Removal of organic matter and nitrogen under upper recirculation conditions was greater than those under bottom recirculation conditions. The average chemical oxygen demand and solids removals were over 99 and over 97% under upper recirculation conditions. Total nitrogen and total phosphorus removals were over 77 and over 69% at recirculation 3 under upper recirculation conditions.

The present and future air contamination by mercury is and will continue to be a serious risk for human health. This publication presents a review of the literature dealing with the issues related to air contamination by mercury and its transformations as well as its natural and anthropogenic emissions. The assessment of mercury emissions into the air poses serious methodological problems. It is particularly difficult to distinguish between natural and anthropogenic emissions and re-emissions from lands and oceans, including past emissions. At present, the largest emission sources include fuel combustion, mainly that of coal, and “artisanal and small-scale gold mining” (ASGM). The distinctly highest emissions can be found in South and South-East Asia, accounting for 45% of the global emissions. The emissions of natural origin and re-emissions are estimated at 45–66% of the global emissions, with the largest part of emissions originating in the oceans. Forecasts on the future emission levels are not unambiguous; however, most forecasts do not provide for reductions in emissions. Ninety-five percent of mercury occurring in the air is Hg⁰—GEM, and its residence time in the air is estimated at 6 to 18 months. The residence times of its Hgᴵᴵ—GOM and that in Hgₚ—TPM are estimated at hours and days. The highest mercury concentrations in the air can be found in the areas of mercury mines and those of ASGM. Since 1980 when it reached its maximum, the global background mercury concentration in the air has remained at a relatively constant level.