The degradation of 230 mL of a 0.6-mM sulfanilamide solution in 0.05 M Na₂SO₄of pH 3.0 has been studied by electro-Fenton process. The electrolytic cell contained either a Pt or boron-doped diamond (BDD) anode and a carbon-felt cathode. Under these conditions, organics are oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between initially added (and then electrochemically regenerated) Fe²⁺and cathodically generated H₂O₂. From the decay of sulfanilamide concentration determined by reversed-phase liquid chromatography, an optimum Fe²⁺concentration of 0.20 mM in both cells was found. The drug disappeared more rapidly using BDD than Pt, and, in both cases, it was more quickly removed with raising applied current. Almost total mineralization was achieved using the BDD/carbon-felt cell, whereas the alternative use of Pt anode led to a slightly lower mineralization degree. In both cells, the degradation rate was accelerated at higher current but with the concomitant fall of mineralization current efficiency due to the greater increase in rate of the parasitic reactions of hydroxyl radicals. Reversed-phase liquid chromatography allowed the identification of catechol, resorcinol, hydroquinone, p-benzoquinone, and 1,2,4-trihydroxybenzene as aromatic intermediates, whereas ion exclusion chromatography revealed the formation of malic, maleic, fumaric, acetic, oxalic, formic, and oxamic acids. NH₄⁺, NO₃⁻, and SO₄²⁻ions were released during the electro-Fenton process. A plausible reaction sequence for sulfanilamide mineralization involving all detected intermediates has been proposed. The toxicity of the solution was assessed from the Vibrio fischeri bacteria luminescence inhibition. Although it acquired its maximum value at short electrolysis time, the solution was completely detoxified at the end of the electro-Fenton treatment, regardless of the anode used.

In this paper, degradation of a mixture of three azo dyes was studied by the photo-assisted electrochemical process using an O₂-diffusion cathode containing carbon nanotubes and boron-doped diamond (BDD) anode. The concentration of three textile dyes (C.I. Acid Orange 8 (AO8), C.I. Acid Orange 10 (AO10), and C.I. Acid Orange 12 (AO12)) was determined simultaneously despite the severe overlap of their spectra. For this purpose, partial least square (PLS), as a multivariate calibration method, was utilized based on recording UV–Vis spectra during the decolorization process. Moreover, the central composite design was used for the modeling of photo-assisted electrochemical decolorization of the aqueous solutions containing three dyes. The investigated parameters were the initial concentration of three dyes, applied current and reaction time. Analysis of variance (ANOVA) revealed that the obtained regression models match the experimental results well with R (Khataee et al. 2010, Clean-Soil Air Water 38 (1):96–103, 2010) of 0.972, 0.971, and 0.957 for AO8, AO10, and AO12, respectively. Three-dimensional surface and contour plots were applied to describe the relation between experimental conditions and the observed response. The results of TOC analysis confirmed good ability of proposed photo-assisted electrochemical process for degradation and mineralization of textile industry wastewater.

In mosquito control programs, insecticides of botanical origin have the potential to eliminate eggs, larvae, and adults. So, the larvicidal, ovicidal, and oviposition-deterrent activities of petroleum ether and ethyl acetate extracts of the leaves of Eugenia jambolana, Solidago canadensis, Euodia ridleyi, and Spilanthes mauritiana were assayed against the three vector mosquito species, namely Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The larval bioassay was conducted following the World Health Organization method. The maximum larval mortality was found with ethyl acetate extract of S. mauritiana against the larvae of A. stephensi, A. aegypti, and C. quinquefasciatus with LC₅₀values of 11.51, 28.1, 14.10 ppm, respectively. The mean percent hatchability of the ovicidal activity was observed at 48-h post-treatment. The percent hatchability was found to be inversely proportional to the concentration of the extract and directly proportional to the number of eggs. The flower head extract of S. mauritiana gave 100 % mortality followed by E. ridleyi, S. canadensis, and E. jambolana against the eggs of the three mosquito vectors. For oviposition-deterrent effect, out of the five concentrations tested (20, 40, 60, 80, and 100 ppm), the concentration of 100 ppm showed a significant egg laying-deterrent capacity. The oviposition activity index value of E. jambolana, E. ridleyi, S. canadensis, and S. mauritiana against A. aegypti, A. stephensi, C. quinquefasciatus at 100 ppm were −0.71, −0.71, −0.90, −0.93, −0.85, −0.91, −1, −1, −0.71, −0.85, −1, and −1, respectively. These results suggest that the leaf/flower extracts of certain local plants have the potential to be developed as possible eco-friendly means for the control of mosquitoes.

In this study, an environmental assessment on an electrokinetic (EK) system for the remediation of a multimetal-contaminated real site was conducted using a green and sustainable remediation (GSR) tool. The entire EK process was classified into major four phases consisting of remedial investigations (RIs), remedial action construction (RAC), remedial action operation (RAO), and long-term monitoring (LTM) for environmental assessment. The environmental footprints, including greenhouse gas (GHG) emissions, total energy used, air emissions of criteria pollutants, such as NOₓ, SOₓ, and PM₁₀, and water consumption, were calculated, and the relative contribution in each phase was analyzed in the environmental assessment. In the RAC phase, the relative contribution of the GHG emissions, total energy used, and PM₁₀emissions were 77.3, 67.6, and 70.4 %, respectively, which were higher than those of the other phases because the material consumption and equipment used for system construction were high. In the RAO phase, the relative contributions of water consumption and NOₓand SOₓemissions were 94.7, 85.2, and 91.0 %, respectively, which were higher than those of the other phases, because the water and electricity consumption required for system operation was high. In the RIs and LTM phases, the environmental footprints were negligible because the material and energy consumption was less. In conclusion, the consumable materials and electrical energy consumption might be very important for GSR in the EK remediation process, because the production of consumable materials and electrical energy consumption highly affects the GHG emissions, total energy used, and air emissions such as NOₓand SOₓ.

Formaldehyde is classified as a human carcinogen that may cause nasopharyngeal cancer and probably leukemia. The effects of environmental and nutritional factors on fungal growth and the biodegradation of formaldehyde were investigated. Fungal strains SGFA1 and SGFA3 isolated from untreated sewage sediment samples collected from heavily formaldehyde-contaminated areas were identified using morphological characteristics and molecular techniques and named as Aspergillus nomius SGFA1 and Penicillium chrysogenum SGFA3. Results indicate that SGFA1 and SGFA3 completely consumed 3,000 and 900 mg l⁻¹of formaldehyde, respectively, within 7 days under optimized conditions. Quantitative real-time PCR analyses and enzyme activity analyses demonstrated that glutathione-dependent formaldehyde dehydrogenase (GDFADH) and formate dehydrogenase (FDH) pathway may play a functional role in enhancing formaldehyde-degrading capability in SGFA1. Both fungi have potential use for remediation of formaldehyde pollution.

Ammonia (NH₃) is an important base gas and can react with acidic species to form atmospheric aerosols. Due to the rapid growth of poultry and swine production in the North Carolina Coastal Plain, atmospheric NH₃concentrations across the region have subsequently increased. Ammonia concentrations and inorganic particulate matter (PM) at four ambient stations in the vicinity of an egg production facility were measured for 1 year using PM₂.₅speciation samplers with honeycomb denuders and ion chromatography (IC). Meanwhile, concentrations of NH₃and inorganic PM in one of the egg production houses were also simultaneously measured using a gas analyzer for NH₃and the filter pack plus IC method for inorganic PM. An equilibrium model-ISORROPIA II was applied to predict the behavior of inorganic aerosols in response to precursor gas concentrations and environmental parameters. Average ambient NH₃concentrations varied from 10.0 to 27.0 μg/m³, and they were negatively correlated with the distances from the ambient location to the nearest egg production house exhausts. Ambient NH₃concentrations were higher in warm seasons than in cold seasons. Measured NH₃concentrations agreed well with ISORROPIA II model predictions at all sampling stations. For the ambient stations, there was a good agreement in particle phase NH₄⁺between the model simulation and observations. For the in-house station, the model simulation was applied to correct the overestimation of particle phase NH₄⁺due to gas phase NH₃breaking through the denuders. Changes in SO₄²⁻, NO₃⁻, and Cl⁻yield proportional changes in inorganic PM mass. Due to the abundance of NH₃gas in the vicinity area of the monitored farm, changes in NH₃concentrations had a small effect on inorganic PM mass. Aerosol equilibrium modeling may be used to assess the influence of precursor gas concentrations on inorganic PM formation when the measurements for some species are unavailable.

To assess the concentration and status of metal contaminants in four major Southeast Asian river systems, water were collected from the Tonle Sap–Bassac Rivers (Cambodia), Citarum River (Indonesia), lower Chao Phraya River (Thailand), and Saigon River (Vietnam) in both dry and wet seasons. The target elements were Be, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Ba, Tl, and Pb and the concentrations exceeded the background metal concentrations by 1- to 88-fold. This distinctly indicates enrichment by human urban area activities. The results of a normalization technique used to distinguish natural from enriched metal concentrations confirmed contamination by Al, Cd, Co, Mn, Ni, Pb, and Zn. Cluster analysis revealed the probable source of metals contamination in most sampling sites on all rivers studied to be anthropogenic, including industrial, commercial, and residential activities. Stable lead isotopes analyses applied to track the sources and pathways of anthropogenic lead furthermore confirmed that anthropogenic sources of metal contaminated these rivers. Discharges of wastewater from both industrial and household activities were major contributors of Pb into the rivers. Non-point sources, especially road runoff and street dust, also contributed contamination from Pb and other metals.

The concentrations of 15 priority PAHs were determined in the atmospheric gaseous and particulate phases from nine sites across Assiut City, Egypt. While naphthalene, acenaphthene, and fluorene were the most abundant in the gaseous phase with average concentrations of 377, 184, and 181 ng/m³, benzo[b]fluoranthene, chrysene, and benzo[g,h,i]perylene showed the highest levels in the particulate phase with average concentrations of 76, 6, and 52 ng/m³. The average total atmospheric concentration of target PAHs (1,590 ng/m³) indicates that Assiut is one of the highest PAH-contaminated areas in the world. Statistical analysis revealed a significant difference between the levels of PAHs in the atmosphere of urban and suburban sites (P = 0.029 and 0.043 for gaseous and particulate phases, respectively). Investigation of diagnostic PAH concentration ratios revealed vehicular combustion and traffic exhaust emissions as the major sources of PAHs with a higher contribution of gasoline rather than diesel vehicles in the sampled areas. Benzo[a]pyrene has the highest contribution (average = 32, 4 % for gaseous and particulate phases) to the total carcinogenic activity (TCA) of atmospheric PAHs. While particulate phase PAHs have higher contribution to the TCA, gaseous phase PAHs present at higher concentrations in the atmosphere are more capable of undergoing atmospheric reactions to form more toxic derivatives.

Vehicles are a major source of air pollution, especially particulate matter (PM) pollution, throughout the world and auto-rickshaws are considered main contributors to this air pollution. PM, in addition to causing respiratory and cardiovascular disorders, has potential to gain access to the brain and could induce neuroinflammation leading to different neurological disorders. Therefore, in the current project, MRI and immunohistochemistry techniques were adopted to ascertain the neurotoxic potential of the chronic exposure to different PM generated by two-stroke auto-rickshaws (TSA), four-stroke auto-rickshaws (FSA), and aluminum sulfate (AS) solution in rats. The results highlighted that all treated groups followed a pattern of dose-dependent increase in pure cortical neuronal loss, selective neuronal loss (SNL), nuclear pyknosis, karyolysis, and karyorrhexis. Mild to moderate areas of penumbra were also observed with increase in the population of activated microglia and astrocytes, while no alteration in the intensities of T₂W MRI signals was perceived in any group. When comparing the findings, TSA possess more neurotoxic potential than FSA and AS, which could be associated with increased concentration of certain elements in TSA emissions. The study concludes that chronic exposure to PM from TSA, FSA, and AS solutions produces diverse neuropathies in the brain, which may lead to different life-threatening neurological disorders like stroke, Alzheimer's, and Parkinson's disorders. Government and environmental agencies should take serious notice of this alarming situation, and immediate steps should be implemented to improve the standards of PM emissions from auto-rickshaws.

Although polychlorinated biphenyls (PCBs) have been banned in many countries for more than three decades, exposures to PCBs continue to be of concern due to their long half-lives and carcinogenic effects. In National Institute for Occupational Safety and Health studies, we are using semiquantitative plant-specific job exposure matrices (JEMs) to estimate historical PCB exposures for workers (n = 24,865) exposed to PCBs from 1938 to 1978 at three capacitor manufacturing plants. A subcohort of these workers (n = 410) employed in two of these plants had serum PCB concentrations measured at up to four times between 1976 and 1989. Our objectives were to evaluate the strength of association between an individual worker’s measured serum PCB levels and the same worker’s cumulative exposure estimated through 1977 with the (1) JEM and (2) duration of employment, and to calculate the explained variance the JEM provides for serum PCB levels using (3) simple linear regression. Consistent strong and statistically significant associations were observed between the cumulative exposures estimated with the JEM and serum PCB concentrations for all years. The strength of association between duration of employment and serum PCBs was good for highly chlorinated (Aroclor 1254/HPCB) but not less chlorinated (Aroclor 1242/LPCB) PCBs. In the simple regression models, cumulative occupational exposure estimated using the JEMs explained 14–24 % of the variance of the Aroclor 1242/LPCB and 22–39 % for Aroclor 1254/HPCB serum concentrations. We regard the cumulative exposure estimated with the JEM as a better estimate of PCB body burdens than serum concentrations quantified as Aroclor 1242/LPCB and Aroclor 1254/HPCB.