Real-world vehicle emissions: a summary of the Thirteenth Coordinating Research Council On-Road Vehicle Emissions Workshop

The Coordinating Research Council held its thirteenth Vehicle Emissions Workshop in April 2003, when results of the most recent on-road vehicle emissions research were presented. Ongoing work from researchers who are engaged in improving understanding of the contribution of mobile sources to ambient air quality and emission inventories is summarized here. Participants in the workshop discussed efforts to improve mobile source emission models, the role of on-board diagnostic systems in inspection and maintenance programs, light- and heavy-duty vehicle emissions measurements, on- and off-road emissions measurements, effects of fuels and lubricating oils on emissions, as well as topics for future research.     

Tropical Coastal Organisms as Qualitative Indicators of Mercury and Organomercury for Sustainable Use of Living Resources

Organisms sensitive to ambient environment are used as bioindicators in monitoring pollution. The present investigation is designed to measure the extent of mercury and organomercury levels in selective biota of different trophic levels inhabiting in the coastal environment of Sunderban Biosphere Reserve, eastern part of India. The primary objective of this work is to provide baseline data for future environmental quality programme and to ascertain the suitability of these organisms to be used as bioindicator species of pollution. The seagrass (Porterasia coarctata), macrobenthos (polychaetes, gastropods and bivalve molluscs) and pelagic finfishes were collected from sites of different physiochemical characteristics. Concentration of total mercury was determined by cold vapour atomic absorption spectrophotometry technique (CVAAS) using a Perkin-Elmer 2380 AAS equipped with MHS 10.Both mercury and organomercury levels showed considerable interspecific and regional variations which reflected the feeding strategy of these animals and also the location of stations. The bivalve molluscs showed a high degree of organ-specificity in accumulation which might be attributed to the ion exchange activity of mucous membrane covering gill and mantle. Mercury levels in various compartments did not reveal any regular temporal variations but showed a slight increase in the late monsoon months indicating the apparent influence of river run-off and reduction in salinity in the ambient medium. A continuous monitoring programme is recommended in order to clarify the present trend and to establish the studied organisms as indicator species.     

Heavy metal contamination in river water and sediments of the Swarnamukhi River Basin,India: risk assessment and environmental implications

The concentration of heavy metals was analyzed each of 20 river water, suspended sediments and bed sediments along the stretch of Swarnamukhi River Basin. River water is not contaminated with heavy metals except Fe and Mn. Contamination factor in sediments shows considerable to very high degree contamination with Cr, Cu, Pb and Zn. The sources of these metals could be residential wastes, sewer outfall, fertilizers, pesticides (M-45 + carbondine) and traffic activities apart from natural weathering of granitic rocks present in the basin area. Principal component analyses indicate the interaction between metals in different media. The comparison of metals (Cu, Pb and Zn) in bed sediments of Swarnamukhi River with the Indian and world averages indicates that the values obtained in the basin are above the Indian averages and far below to the world averages. Average shale values and sediment quality guidelines point toward the enrichment and contamination of Cu, Cr, Pb and Zn to several fold leading to eco-toxicological risks in basin.     

Growth inhibition of bloom forming cyanobacterium Microcystis aeruginosa by green route fabricated copper oxide nanoparticles

The cyanobacterium Microcystis aeruginosa can potentially proliferate in a wide range of freshwater bionetworks and create extensive secondary metabolites which are harmful to human and animal health. The M. aeruginosa release toxic microcystins that can create a wide range of health-related issues to aquatic animals and humans. It is essential to eliminate them from the ecosystem with convenient method. It has been reported that engineered metal nanoparticles are potentially toxic to pathogenic organisms. In the present study, we examined the growth inhibition effect of green synthesized copper oxide nanoparticles against M. aeruginosa. The green synthesized copper oxide nanoparticles exhibit an excitation of surface plasmon resonance (SPR) at 270 nm confirmed using UV–visible spectrophotometer. The dynamic light scattering (DLS) analysis revealed that synthesized nanoparticles are colloidal in nature and having a particle size of 551 nm with high stability at ?26.6 mV. The scanning electron microscopy (SEM) analysis shows that copper oxide nanoparticles are spherical, rod and irregular in shape, and consistently distributed throughout the solution. The elemental copper and oxide peak were confirmed using energy dispersive x-ray analysis (EDAX). Fourier-transform infrared (FT-IR) spectroscopy indicates the presence of functional groups which is mandatory for the reduction of copper ions. Besides, green synthesized copper oxide nanoparticles shows growth inhibition against M. aeruginosa. The inhibition efficiency was 31.8 % at lower concentration and 89.7 % at higher concentration of copper oxide nanoparticles, respectively. The chlorophyll (a and b) and carotenoid content of M. aeruginosa declined in dose-dependent manner with respect to induction of copper oxide nanoparticles. Furthermore, we analyzed the mechanism behind the cytotoxicity of M. aeruginosa induced by copper oxide nanoparticles through evaluating membrane integrity, reactive oxygen species (ROS), and mitochondrial membrane potential (Δψm) level. The results expose that there is a loss in membrane integrity with ROS formation that leads to alteration in the Δψm, which ends up with severe mitochondrial injury in copper oxide nanoparticles treated cells. Hence, green way synthesized copper oxide nanoparticles may be a useful selective biological agent for the control of M. aeruginosa.     

Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia

The mesostructured materials MCM-41 and SBA-15 were studied as possible supports of bromocresol green (BG) dye impregnation for the ammonia gas detection because of their large surface area, high regenerative property, and high thermal stability. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and N₂ adsorption analysis were used to characterize the prepared materials. These materials could sense ammonia via visible color change from yellowish-orange to blue color. The color change process of the nanostructured materials was fully reversible during 10 cyclic tests. The results indicated that the ammonia absorption responses of the two nanostructured materials were both very sensitive, and high linear correlation and high precision were achieved. As the gaseous ammonia concentrations were 50 and 5 ppmv, the response times for the SBA-15/BG were only 1 and 5 min, respectively. Moreover, the BG dye-impregnated SBA-15 was less affected by the variation in the relative humidity. It also had faster response for the detection of NH₃, as well as lower manufacturing price as compared to that of the dye-impregnated MCM-41. Such feature enables SBA-15/BG to be a very promising material for the detection of ammonia gas.

Implications: The detector tube is a convenient ambient ammonia detection device. However, almost all the commercial detector tubes can be used once only, which not only increases the purchase cost but also produces lots of waste. In this study, we developed two sensing materials that are sensitive for repeated usage. The two mesoporous silica-based materials, MCM-41 and SBA-15, are impregnated by an organic dye of bromocresol green to induce color change behavior that can be easily observed by the naked eye, and it is concluded that dye-impregnated SBA-15/BG is a very promising material for the detection of ammonia gas.     

Use of activated Chromolaena odorata biomass for the removal of crystal violet from aqueous solution: kinetic,equilibrium, and thermodynamic study

Environmental Science and Pollution Research - In the present study, biomass from the Chromolaena odorata plant’s stem was activated using sulfuric acid to adsorb crystal violet (CV) dye. The...     

Remediation and toxicity of endocrine disruptors: a review

Environmental Chemistry Letters - Endocrine disruptors are hazardous chemicals with chronic health effects for most living organisms, inducing homeostasis, hormonal imbalances, cancer, reproductive...     

Identification of sources affecting fog formation using receptor modeling approaches and inventory estimates of sectoral emissions

Positive matrix factorization (PMF) was used to identify factors affecting fog formation in Kanpur during the ISRO-GBP land campaign-II (LC-II) in December 2004. PMF predicted factors were validated by contrasting the emission strength of sources in the foggy and clear periods, using a combination of potential source contribution function (PSCF) analysis and quantitative emission inventory information. A time series aerosol chemical data set of 29 days and 12 species was decomposed to identify 4-factors: Secondary species, Biomass burning, Dust and Sea salt. PMF predicted particle mass with a satisfactory goodness-of-fit (slope of 0.83 ± 0.17 and R² of 0.8), and strong species within 11–12% relative standard deviation. Mean contributions of anthropogenic factors were significantly higher during the foggy period for secondary species (2.9 ± 0.3) and biomass burning (1.2 ± 0.09) compared to the clear period. Local sources contributing to aerosols that mediated fog events at Kanpur, based on emissions in a 200 km × 200 km area around Kanpur city were thermal power plants and transportation (SO₂) and biofuel combustion (BC and OM). Regional scale sources influencing emissions during the foggy period, in probable source regions identified by PSCF included thermal power plants, transportation, brick kilns and biofuel combustion. While biofuel combustion and transportation are distributed area sources, individual point sources include coal-fired thermal power plants located in Aligarh, Delhi, Ghaziabad, Jhansi, Kanpur, Rae Bareli and Rupnagar and brick kilns located in Allahabad, Agra, Farrukhabad, Ghaziabad, Kanpur, Ludhiana, Lucknow and Rae Bareli. Additionally, in the foggy period, large areas of probable source regions lay outside India, implying the significance of aerosol incursion from outside India.     

Real-world vehicle emissions: a summary of the Seventeenth Coordinating Research Council On-Road Vehicle Emissions Workshop

The Coordinating Research Council, Inc. (CRC) held its 17th On-Road Vehicle Emissions Workshop in March 2007, where results of the most recent on-road vehicle emissions research were presented. We summarize ongoing work from researchers who are engaged in improving our understanding of the role and contribution of mobile sources to ambient air quality and emission inventories. Participants in the Workshop discussed efforts to improve mobile source emission models, light- and heavy-duty vehicle emissions measurements, on- and off-road emissions measurements, effects of fuels and lubricating oils on emissions, as well as emerging issues and topics for future research.     

Phytoextraction of heavy metal polluted soils using Sedum plumbizincicola inoculated with metal mobilizing Phyllobacterium myrsinacearum RC6b

The aim of this study was to investigate the effects of metal mobilizing plant-growth beneficial bacterium Phyllobacterium myrsinacearum RC6b on plant growth and Cd, Zn and Pb uptake by Sedum plumbizincicola under laboratory conditions. Among a collection of metal-resistant bacteria, P. myrsinacearum RC6b was specifically chosen as a most favorable metal mobilizer based on its capability of mobilizing high concentrations of Cd, Zn and Pb in soils. P. myrsinacearum RC6b exhibited a high degree of resistance to Cd (350 mg L⁻¹), Zn (1000 mg L⁻¹) and Pb (1200 mg L⁻¹). Furthermore, P. myrsinacearum RC6b showed multiple plant growth beneficial features including the production of 1-aminocyclopropane-1-carboxylic acid deaminase, indole-3-acetic acid, siderophore and solubilization of insoluble phosphate. Inoculation of P. myrsinacearum RC6b significantly increased S. plumbizincicola growth and organ metal concentrations except Pb, which concentration was lower in root and stem of inoculated plants. The results suggest that the metal mobilizing P. myrsinacearum RC6b could be used as an effective inoculant for the improvement of phytoremediation in multi-metal polluted soils.