This study examines gaseous chlorinated species generated from the reaction of sulfur dioxide (SO₂) with sodium chlorite powder (NaClO₂₍ₛ₎) to obtain insight into the propensity of this process to enhance NO and Hg⁰oxidation. A packed bed reactor containing NaClO₂₍ₛ₎was used and the reaction temperature was set to 130 °C. Initially, we determined that the presence of SO₂enhances the oxidation of NO and Hg⁰by reaction with NaClO₂₍ₛ₎. We then introduced NO₂into the gas mixture as a radical scavenger and determined that the chlorinated species generated by the reaction of SO₂with NaClO₂₍ₛ₎are OClO, Cl, ClO, and Cl₂. Based on these results, we suggest that such gaseous chlorinated ones are responsible for the enhancement of NO and Hg⁰oxidation.

In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O₃) exposure using hourly O₃concentrations for the period 2002–2007 in India. This study estimates crop yield losses according to two indices of O₃exposure: 7-h seasonal daytime (0900–1600 hours) mean measured O₃concentration (M7) and AOT40 (accumulation exposure of O₃concentration over a threshold of 40 parts per billion by volume during daylight hours (0700–1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11 % (6–30 %) for winter wheat and 3–6 % (9–16 %) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002–2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86–276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O₃concentration and further elevated O₃concentration in future may pose threat to food security.

The intensive use of benzotriazoles as corrosion inhibitors for various applications and their application in dishwasher detergents result in an almost omnipresence of benzotriazole (BTri), 4-methyl- and 5-methyl-benzotriazole (4-TTri and 5-TTri, respectively) in aquatic systems. This study aims on the evaluation of the biodegradation potential of activated sludge communities (ASCs) toward the three benzotriazoles regarding aerobic, anoxic, and anaerobic conditions and different nutrients. ASCs were taken from three wastewater treatment plants with different technologies, namely, a membrane bioreactor (MBR-MH), a conventional activated sludge plant CAS-E (intermittent nitrification/denitrification), and CAS-M (two-stage activated sludge treatment) and used for inoculation of biodegradation setups. All ASCs eliminated up to 30 mg L⁻¹5-TTri and BTri under aerobic conditions within 2–7 and 21–49 days, respectively, but not under anoxic or anaerobic conditions. 4-TTri was refractory at all conditions tested. Significant differences were observed for BTri biodegradation with non-acclimated ASCs from MBR-MH with 21 days, CAS-E with 41 days, and CAS-M with 49 days. Acclimated ASCs removed BTri within 7 days. Furthermore, different carbon and nitrogen concentrations revealed that nitrogen was implicitly required for biodegradation while carbon showed no such effect. The fastest biodegradation occurred for 5-TTri with no need for acclimatization, followed by BTri. BTri showed sludge-specific biodegradation patterns, but, after sludge acclimation, was removed with the same pattern, regardless of the sludge used. Under anaerobic conditions in the presence of different electron acceptors, none of the three compounds showed biological removal. Thus, presumably, aerobic biodegradation is the major removal mechanism in aquatic systems.

Dufulin is a newly developed antiviral agent (or pesticide) that activates systemic acquired resistance of plants. This pesticide is widely used in China to prevent abroad viral diseases in rice, tobacco and vegetables. In this study, the potential impacts such as soil type, moisture, temperature, and other factors on Dufulin degradation in soil were investigated. Degradation of Dufulin followed the first-order kinetics. The half-life values varied from 2.27 to 150.68 days. The dissipation of Dufulin was greatly affected by soil types, with DT₅₀(Degradation half time) varying between 17.59, 31.36, and 43.32 days for Eutric Gleysols, Cumulic Anthrosols, and Dystric Regosols, respectively. The elevated moisture accelerated the decay of Dufulin in soil. Degradation of Dufulin increased with temperature and its half-life values ranged from 16.66 to 42.79 days. Sterilization of soils and treatment with H₂O₂resulted in a 6- and 8-fold decrease in degradation rates compared to the control, suggesting that Dufulin degradation was largely governed by microbial processes. Under different light spectra, the most effective degradation occurred with 100-W UV light (DT₅₀ = 2.27 days), followed by 15-W UV light (DT₅₀ = 8.32 days) and xenon light (DT₅₀ = 14.26 days). Analysis by liquid chromatography-mass spectroscopy (LC-MS) revealed that 2-amino-4-methylbenzothiazole was one of the major decayed products of Dufulin in soils, suggesting that elimination of diethyl phosphate and 2-fluorobenzaldehyde was most like the degradation pathway of Dufulin in Eutric Gleysols.

Fifteen plant species—Alternanthera bettzickiana, Drimiopsis botryoides, Aloe vera, Chlorophytum comosum, Aglaonema commutatum, Cordyline fruticosa, Philodendron martianum, Sansevieria hyacinthoides, Aglaonema rotundum, Fittonia albivenis, Muehlenbeckia platyclada, Tradescantia spathacea, Guzmania lingulata, Zamioculcas zamiifolia, and Cyperus alternifolius—were evaluated for the removal efficiency of xylene from contaminated air. Among the test plants, Z. zamiifolia showed the highest xylene removal efficiency. Xylene was toxic to Z. zamiifolia with an LC₅₀of 3,464 ppm. Higher concentrations of xylene exhibited damage symptoms, including leaf tips turning yellow, holonecrosis, and hydrosis. TEM images showed that a low concentration of xylene vapors caused minor changes in the chloroplast, while a high concentration caused swollen chloroplasts and damage. The effect of photosynthetic types on xylene removal efficiency suggests that a mixture of Z. zamiifolia, S. hyacinthoides, and A. commutatum which represent facultative CAM, CAM, and C₃plants, is the most suitable system for xylene removal. Therefore, for maximum improvement in removing xylene volatile compounds under various conditions, multiple species are needed. The effect of a plant’s total leaf area on xylene removal indicates that at lower concentrations of xylene, a small leaf area might be as efficient as a large leaf area.

The biodegradability of nitrochlorinated (diuron and atrazine) and chlorophenoxy herbicides (2,4-D and MCPA) has been studied through several bioassays using different testing times and biomass/substrate ratios. A fast biodegradability test using unacclimated activated sludge yielded no biodegradation of the herbicides in 24 h. The inherent biodegradability test gave degradation percentages of around 20–30 % for the nitrochlorinated herbicides and almost complete removal of the chlorophenoxy compounds. Long-term biodegradability assays were performed using sequencing batch reactor (SBR) and sequencing batch membrane bioreactor (SB-MBR). Fixed concentrations of each herbicide below the corresponding EC₅₀value for activated sludge were used (30 mg L⁻¹for diuron and atrazine and 50 mg L⁻¹for 2,4-D and MCPA). No signs of herbicide degradation appeared before 35 days in the case of diuron and atrazine and 21 days for 2,4-D, whereas MCPA was partially degraded since the early stages. Around 25–36 % degradation of the nitrochlorinated herbicides and 53–77 % of the chlorophenoxy ones was achieved after 180 and 135 days, respectively, in SBR, whereas complete disappearance of 2,4-D was reached after 80 days in SB-MBR.

Five estrogenic hormones (unconjugated + conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from the WWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.

To understand the transport and fate of antibiotic resistance genes in wastewater treatment plants, 12 resistance genes (ten tetracycline resistance genes, two sulfonamides genes) and class 1 integron gene (intI1) were studied in five wastewater treatment plants with different treatment processes and different sewage sources. Among these resistance genes, sulfonamides genes (sul1 and sul2) were of the most prevalent genes with detection frequency of 100 %. The effluent water contained fewer types of resistance genes than the influent in most selected plants. The abundance of five quantified resistance genes (tetG, tetW, tetX, sul1, and intI1) decreased in effluent of plants treating domestic or industrial wastewater with anaerobic/aerobic or membrane bioreactor (MBR) technologies, but tetG, tetX, sul1, and intI1 increased along the treatment units of plants treating vitamin C production wastewater by anaerobic/aerobic technology. In plant treating cephalosporins production wastewater by UASB/aerobic process, the quantities of tetG, tetX, and sul1 first decreased in anaerobic effluent water but then increased in aerobic effluent water.

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68–1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34–0.5 μm) compared to that (0.28–0.37) at long-wavelength (LW) channels (0.87–1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD₀. ₅) and Angstrom parameter ( α) were 0.68–0.82 and 1.14–1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23–3 μm) which was 60–70 % of aerosol 10- μm (size 0.23–10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred.

L-meta-tyrosine is an herbicidal nonprotein amino acid isolated some years ago from fine fescue grasses and characterized by its almost immediate microbial degradation in soil (half-life <24 h). Nine monohalogenated or dihalogenated analogs of this allelochemical have been obtained through a seven-step stereoselective synthesis from commercial halogenated phenols. Bioassays showed a large range of biological responses, from a growth root inhibition of lettuce seedling similar to that noted with m-tyrosine [2-amino-3-(2-chloro-5-hydroxyphenyl)propanoic acid or compound 8b] to an increase of the primary root growth concomitant with a delay of secondary root initiation [2-amino-3-[2-fluoro-5-hydroxy-3-(trifluoromethyl)phenyl]propanoic acid or compound 8h]. Compound 8b was slightly less degraded than m-tyrosine in the nonsterilized nutritive solution used for lettuce development, while the concentration of compound 8h remained unchanged for at least 2 weeks. These data indicate that it is possible to manipulate both biological properties and degradation of m-tyrosine by halogen addition.