Photo-induced degradation of diuron in aqueous solution by nitrites and nitrates: kinetics and pathways

The photo-induced degradation of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) in aqueous solution under simulated solar irradiation has been investigated in the presence of NO3-/NO2- ions. The degradation rates were compared by varying environmental parameters including substrate and inducer concentrations, oxygen content and pH. The photoproducts were identified by extensive LC-ESI-MS and LC-ESI-MS-MS studies after SPE preconcentration on prepacked cartridges. In both NO3- and NO2- conditions, oxidation of the N-(CH3)2 terminus group is the main process leading to the N-monodemethylated (NHCH3), N-formyl (N(CH3)CHO) and the uncommon and unstable carbinolamine (N(CH3)CH2OH) by-products. Cl/OH substituted and nitrated phenylureas are formed minorily. Degradation pathways involving OH* and NO2* (or dimer) radicals as reactive species are proposed.     

Simultaneous sampling of gas- and aerosol-phase TDI with a triple filter system

A new triple filter system sampler/model is proposed for the precise and accurate simultaneous sampling and determination of gas- and aerosol-phase 2,4-toluene diisocyanate (TDI). The system consists of two front Teflon filters for sampling aerosol-phase TDI and a final coated glass fiber filter to collect gas-phase TDI. The aerosol-phase TDI is collected on the first Teflon filter, while the second Teflon filter is used to estimate gaseous TDI adsorbed by the first. According to the gas adsorption test of two Teflon filters in series, the TDI gas adsorption fraction of the two filters is almost the same. Results of the evaporation test using pure TDI aerosols collected on the Teflon filter show that significant evaporation of the compound does not occur during sampling. These two findings allow the use of a model to estimate accurate gas- and aerosol-phase TDI concentrations. The comparison test with an annular denuder shows that the triple filter system can minimize the TDI sampling bias between the dual filter and the annular denuder systems.     

Effect of cortisol on female freshwater fish Notopterus notopterus

In the present study, effect of cortisol on the ovary of the freshwater fish Notopterus notopterus was studied during four phases of the reproductive cycle. The hormone was injected 60microg/fish for ten days. Cortisol in fish is known to increase the metabolic activity. After the hormone treatment the ovarian somatic index and the hepatosomatic index increases during non breeding phase. The young oocytes transferred into vitellogenic oocytes in all the phases after cortisol treatment. The cortisol induced increased ovarian activity may be due to increase in the metabolic activity through the involvement of hepatic cells specially during non-breeding period providing support for energy production for reproductive activity in the freshwater fish N. notopterus.     

Performance enhancement of solar photovoltaic system for roof top garden

Environmental Science and Pollution Research - The photovoltaic (PV) for irrigation system is an emerging technology to harness the solar energy. The performance of the PV modules depends on the...     

Effect of Zn salts and hydrolyzing agents on the morphology and antibacterial activity of zinc oxide nanoparticles

Environmental Chemistry Letters - Zinc oxide nanoparticles (ZnONPs) are considered safe as antibacterials. Those nanoparticles should preferably have uniform size and shape, but conditions to...     

Soil and plant selenium at a reclaimed uranium mine

Selenium (Se) associated with reclaimed uranium (U) mine lands may result in increased food chain transfer and water contamination. To assess post-reclamation bioavailability of Se at a U mine site in southeastern Wyoming, we studied soil Se distribution, dissolution, speciation, and sorption characteristics and plant Se accumulation. Phosphate-extractable soil Se exceeded the critical limit of 0.5 mg/kg in all the samples, whereas total soil Se ranged from a low (0.6 mg/kg) to an extremely high (26 mg/kg) value. Selenite was the dominant species in phosphate and ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extracts, whereas selenate was the major Se species in hot water extracts. Extractable soil Se concentrations were in the order of KH2PO4 > AB-DTPA > hot water > saturated paste. The soils were undersaturated with respect to various Se solid phases, albeit with high levels of extractable Se surpassing the critical limit. Calcium and Mg minerals were the potential primary solids controlling Se dissolution, with dissolved organic carbon in the equilibrium solutions resulting in enhanced Se availability. Adsorption was a significant (r2 = 0.76-0.99 at P < 0.05) mechanism governing Se availability and was best described by the initial mass isotherm model, which predicted a maximum reserve Se pool corresponding to 87% of the phosphate-extractable Se concentrations. Grasses, forbs, and shrubs accumulated 11 to 1800 mg Se/kg dry weight. While elevated levels of bioavailable Se may be potentially toxic, the plants accumulating high Se may be used for phytoremediation, or the palatable forage species may be used as animal feed supplements in Se-deficient areas.     

Field enhancements of packed-bed performance for low-concentration acidic and basic-waste gases from semiconductor manufacturing process

Low-concentration acidic and basic-waste gas pollutants contribute significantly in the total emission of a facility. Previous results show that the control of high volumetric flow rate (approximately 500 m3/min), low-concentration acidic (< 1 ppm by vol) and basic (< 3 ppm by vol) gases from semiconductor process vent, by conventional wet scrubbing technique is a challenging task. This work was targeted to enhance the performance of packed beds for high-volumetric flow rate, low-concentration acidic (HF, HCl), and basic (NH3)-waste gases from the semiconductor manufacturing process. The methodology used to meet the goal was the application of fine-water mist over the inlet stream before entering to the packed bed and use of the surfactant with mist/packed-bed liquid in low concentration. An experimental study was carried out in two acid-packed beds to optimize the operating conditions, such as pH of the liquid, circulating liquid flow rate, blow-down cycle, and so forth. The relationship among liquid pH, liquid ionic concentration, and the removal efficiency of the packed bed for the pollutants has been discussed considering chemical equilibrium, two-film theory, and Henry's law. For the potential utilization of scrubbing water, the dependency of the efficiency on blow-down cycle was studied, and a mechanism is suggested. The proposed water-mist surfactant system was installed in two acid-packed beds, and performance of the packed beds was compared. The background efficiencies of the acid-packed beds for HF, HCl, and NH3 were found max to be (n = 11) 53, 40, and 27%, whereas after installation of the system, they increased significantly and became 76 +/- 13% (n = 10), 76 +/- 8% (n = 7), and 78 +/- 7% (n = 7), respectively, for inlet concentrations of HF and HCl < 1 ppm and NH3 < 14 ppm. The mechanism by which the surfactants operate to enhance the removal in scrubbing process is suggested considering the hydrodynamic effect and the interfacial effect with the charge-generating characteristic of surfactants on water surface, when dissolved into water. The results show that a proposed rectification system can effectively reduce the emission rates below the regulatory level (0.6 kg/hr) at the present conditions of the facility.     

Evaluation of vibrant muscles over the shoulder region among workers of the hand screen printing industry

This study focuses on evaluation of the muscle activities associated with shoulder pain among workers of the hand screen printing (HSP) industry. Activities of three major muscles which showed higher muscle activity for a HSP job were observed for fatigue using surface electromyography (SEMG). The anatomical sites were chosen on the basis of a statistical survey and a visual inspection conducted before the experiment. Activities of the deltoid, teres major and infraspinatus were recorded using SEMG and the nature of muscle activities was studied for about 50?m of cloth printing. Data collected were processed using LabVIEW 2014 and the activities were analyzed using statistical tests and regression analyses. The results showed an increased risk of shoulder disorders with an increase in working time. Some of the risks which might cause disorders were predicted from the results; inspection and possible mitigations were suggested.     

Diversity of phytoplanktons in a waste stabilization pond at Shimoga Town, Karnataka State, India

To understand the diversity of phytoplanktons in waste stabilization pond effluents the hitherto study is undertaken. Species diversity indices of Shannon-Wiener and Simpson were applied to phytoplanktons. The diversity indices are of mathematical function to explain the abundance of each species. The total numbers of algae identified were 71 species belonging to Cyanophyceae, Chlorophyceae, Euglenophyceae, Bacillariophyceace and Desmidaceae. Chlorella and Scenedesmus were the dominant forms among the algal genera throughout the study period. Phytoplanktons play a vital role in improving the water quality of wastewater in waste stabilization ponds. Diversity indices provide important information about rarity and commonness of species in a community. The diversity indices of all the species explained the water was moderately polluted with less diversity level and highest possible equal number of different species of phytoplanktons. Greater impact of pollution leads to the lesser diversity of phytoplanktons.     

Impact of industrialization on groundwater quality – a case study of Peenya industrial area, Bangalore, India

The present study aims at identifying the groundwater contamination problems in Bangalore city in India. Groundwater samples from 30 different locations of the industrial area were collected. Analytical techniques as described in the Standard methods for the examination of water and wastewater were adopted for physico-chemical analysis of these samples and the results compared with the Bureau of Indian Standards (BIS) guideline values for potable water in the light of possible health hazards. The investigations reveal that most of the study area is highly contaminated due to the excessive concentrations of one or more water quality parameters such as Nitrates, Total Hardness, Calcium, Magnesium, Total dissolved solids, Sulphates and Fluorides, which have rendered nearly 77% of the water samples tested, non- potable. Discussions held by the authors with the local public as well as the Primary health centre authorities of the area revealed that a lot of people in the area are suffering from severe health problems on using this water. The findings show that there is a clear correlation between the ill health faced by the public and contamination of the said groundwaters.