Macro-porous resins are widely used as adsorbents for the treatment of organic contaminants in wastewater and for the pre-concentration of organic solutes from water. However, the sorption mechanisms for organic contaminants on such adsorbents have not been systematically investigated so far. Therefore, in this study, the sorption capacities and affinities of 24 organic chemicals by XAD-7 were investigated and the experimentally obtained sorption isotherms were fitted to the Dubinin-Ashtakhov model. Linear positive correlations were observed between the sorption capacities and the solubilities (S W) of the chemicals in water or octanol and between the sorption affinities and the solvatochromic parameters of the chemicals, indicating that the sorption of various organic compounds by XAD-7 occurred by non-linear partitioning into XAD-7, rather than by adsorption on XAD-7 surfaces. Both specific interactions (i.e., hydrogen-bonding interactions) as well as nonspecific interactions were considered to be responsible for the non-linear partitioning. The correlation equations obtained in this study allow the prediction of non-linear partitioning using well-known chemical parameters, namely S W, octanol-water partition coefficients (K OW), and the hydrogen-bonding donor parameter (α ₘ). The effect of pH on the sorption of ionizable organic compounds (IOCs) could also be predicted by combining the correlation equations with additional equations developed from the estimation of IOC dissociation rates. The prediction equations developed in this study and the proposed non-linear partition mechanism shed new light on the selective removal and pre-concentration of organic solutes from water and on the regeneration of exhausted XAD-7 using solvent extraction.

The effect of insecticides (acephate and imidacloprid) on a freshwater microalga Chlamydomonas mexicana was investigated with respect to photosynthetic pigments, carbohydrate and protein contents, fatty acids composition and induction of stress indicators including proline, superoxide dismutase (SOD) and catalase (CAT). C. mexicana was cultivated with 1, 5, 10, 15, 20 and 25 mg L⁻¹ of acephate and imidacloprid. The microalga growth increased with increasing concentrations of both insecticides up to 15 mg L⁻¹, beyond which the growth declined compared to control condition (without insecticides). C. mexicana cultivated with 15 mg L⁻¹ of both insecticides for 12 days was used for further analysis. The accumulation of photosynthetic pigments (chlorophyll and carotenoids), carbohydrates and protein was decreased in the presence of both insecticides. Acephate and imidacloprid induced the activities of superoxide dismutase (SOD) and catalase (CAT) and increased the concentration of proline in the microalga, which play a defensive role against various environmental stresses. Fatty acid analysis revealed that the fraction of polyunsaturated fatty acids decreased on exposure to both insecticides. C. mexicana also promoted 25 and 21 % removal of acephate and imidacloprid, respectively. The biochemical changes in C. mexicana on exposure to acephate and imidacloprid indicate that the microalga undergoes an adaptive change in response to the insecticide-induced oxidative stress.

This study aims to investigate the relationship between carbon dioxide (CO₂) emissions, energy consumption, real output (GDP), the square of real output (GDP²), trade openness, urbanization, and financial development in the USA for the period 1960–2010. The bounds testing for cointegration indicates that the analyzed variables are cointegrated. In the long run, energy consumption and urbanization increase environmental degradation while financial development has no effect on it, and trade leads to environmental improvements. In addition, this study does not support the validity of the environmental Kuznets curve (EKC) hypothesis for the USA because real output leads to environmental improvements while GDP² increases the levels of gas emissions. The results from the Granger causality test show that there is bidirectional causality between CO₂ and GDP, CO₂ and energy consumption, CO₂ and urbanization, GDP and urbanization, and GDP and trade openness while no causality is determined between CO₂ and trade openness, and gas emissions and financial development. In addition, we have enough evidence to support one-way causality running from GDP to energy consumption, from financial development to output, and from urbanization to financial development. In light of the long-run estimates and the Granger causality analysis, the US government should take into account the importance of trade openness, urbanization, and financial development in controlling for the levels of GDP and pollution. Moreover, it should be noted that the development of efficient energy policies likely contributes to lower CO₂ emissions without harming real output.

TiO₂ and Ag NPs are widely used as antibacterial agents against many bacterial pathogens. Chitosan (polymer) itself acts as a strong antibacterial agent. Hence, chitosan/TiO₂/Ag NPs incorporated nanocomposite film was prepared against packed drinking water bacterial strains. A concentration-dependent increase in the reduction of cell viability was observed in all the isolates under UV-C and dark exposure conditions. The bacteria consortium showed greater resistance against antibacterial effects of chitosan/TiO₂/Ag nanocomposite as compared to single isolates. Glycocalyx test and mass assessment conclude the effective antibacterial activity by inhibiting bacterial adhesion on the film surface. The release of LDH and generation of ROS act as the predominant antibacterial mechanism induced by TiO₂/Ag NPs. Surface characterization of chitosan/TiO₂/Ag nanocomposite was studied by FTIR and XRD analyses and SEM analysis after interaction with the bacteria.

Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

Vermicomposting (VC) has proven to be a promising method for treating garden, household, and municipal wastes. Although the VC has been used extensively for converting wastes into fertilizers, pathogens such as Escherichia coli (E. coli) survival during this process is not well documented. In this study, both lab and field scale experiments were conducted assessing the impacts of earthworms in reducing E. coli concentration during VC of food waste. In addition, other pertinent parameters such as temperature, carbon and nitrogen content, moisture content, pH, volatile solids, micronutrients (P, K, Ca, Mg, and S), and heavy metals (Zn, Mn, Fe, and Cu) were monitored during the study. The lab and field scale experiments were conducted for 107 and 103 days, respectively. The carbon to nitrogen ratio (C/N) decreased by 54 % in the lab scale study and by 36 % in the field study. Results showed that VC was not significantly effective in reducing E. coli levels in food waste under both lab and field scale settings. The carbon to nitrogen ratio (C/N) decreased by 54 % in the lab scale study and by 36 % in the field study.

Groundwater nitrate pollution is one of the most prevalent water-related environmental problems worldwide. The objective of this study is to identify the determinants of nitrogen pollutant changes with a focus on the nitrogen generation process. The novelty of our research framework is to cost-effectively identify the factors involved in nitrogen pollutant generation using public data. This study focuses on three determinant factors: (1) nitrogen intensity changes, (2) structural changes, and (3) scale changes. This study empirically analyses three sectors, including crop production, farm animals, and the household, on the Shimabara Peninsula in Japan. Our results show that the nitrogen supply from crop production sectors has decreased because the production has been scaled down and shifted towards lower nitrogen intensive crops. In the farm animal sector, the nitrogen supply has also been successfully reduced due to scaling-down efforts. Households have decreased the nitrogen supply by diffusion of integrated septic tank and sewerage systems.

The aim of this study was to evaluate the effect of bioaugmentation and addition of rhamnolipids on the biodegradation of PAHs in artificially contaminated soil, expression of genes crucial for the biodegradation process (PAHRHDαGN, PAHRHDαGP), and the synthesis of rhamnolipids as well as population changes in the soil bacterial metabiome. The positive effect of bioaugmentation and addition of rhamnolipids on the bioremediation of the majority of PAHs was confirmed during the early stages of treatment, especially in case of the most structurally complicated compounds. The results of metagenomic analysis indicated that the initial changes in the soil metabiome caused by bioaugmentation diminished after 3 months and that the community structure in treated soil was similar to control. The survival period of bacteria introduced into the soil via bioaugmentation reached a maximum of 3 months. The increased expression of genes observed after addition of PAH into the soil also returned to the initial conditions after 3 months.

PCBs are persistent organic pollutants that are carcinogenic and immunotoxic and have developmental toxicity. This suggests that they may interfere with normal cell maturation. Cancer and stem/progenitor cells have telomerase activity to maintain and protect the chromosome ends, but lose this activity during differentiation. We hypothesized that PCBs interfere with telomerase activity and the telomere complex, thereby disturbing cell differentiation and stem/progenitor cell function. HL-60 cells are cancer cells that can differentiated into granulocytes and monocytes. We exposed HL-60 cells to PCB126 (dioxin-like) and PCB153 (nondioxin-like) 6 days before and during 3 days of differentiation. The differentiated cells showed G0/G1 phase arrest and very low telomerase activity. hTERT and hTR, two telomerase-related genes, were downregulated. The telomere shelterins TRF1, TRF2, and POT1 were upregulated in granulocytes, and TRF2 was upregulated and POT1 downregulated in monocytes. Both PCBs further reduced telomerase activity in differentiated cells, but had only small effects on the differentiation and telomere-related genes. Treatment of undifferentiated HL-60 cells for 30 days with PCB126 produced a downregulation of telomerase activity and a decrease of hTERT, hTR, TRF1, and POT1 gene expression. With PCB153, the effects were less pronounced and some shelterin genes were increased after 30 days of exposure. With each PCB, no differentiation of cells was observed and cells continued to proliferate despite reduced telomerase activity, resulting in shortened telomeres after 30 days of exposure. These results indicate cell-type and PCB congener-specific effects on telomere/telomerase-related genes. Although PCBs do not seem to strongly affect differentiation, they may influence stem or progenitor cells through telomere attrition with potential long-term consequences for health.

A method for measurements of mass concentration of black carbon particulate matter (PM) is proposed based on photothermal interferometry (PTI). A folded Jamin photothermal interferometer was used with a laser irradiation of particles deposited on a filter paper. The black carbon PM deposited on the filter paper was regarded as a film while the quartz filter paper was regarded as a substrate to establish a mathematical model for measuring the mass concentration of PM using a photothermal method. The photothermal interferometry system was calibrated and used to measure the atmospheric PM concentration corresponding to different dust-treated filter paper. The measurements were compared to those obtained using β ray method and were found consistent. This method can be particularly relevant to polluted atmospheres where PM is dominated by black carbon.