Chirashree Ghosh

Ornamental plants as sinks and bioindicators

Mitigation of urban air pollution is a big challenge, especially for the metropolitan cities of the world. In an Indian metropolis like Delhi, even after the implementation of several control policies, no such remarkable change has been observed in its air quality. Globally, afforestation or greenbelt development is an effective and well-recognized pollution abatement process. The aim of our present study was to examine the biochemical response of some naturalized ornamental plant species, viz. Dracaena deremensis, Tagetes erecta, Rosa indica and Dianthus caryophyllus. During experimental study, plants were kept at selected sites which were categorized in terms of traffic density (emission source) and vegetative pattern during winter months for 120 days. Four biochemical parameters, viz. total chlorophyll, ascorbic acid, pH, relative water contents along with Air Pollution Tolerance Indices were determined from foliar samples at each selected site. D. deremensis and T. erecta were classified under tolerant while R. indica and D. caryophyllus were marked as in sensitive category. Based on the sensitivity of selected plant species, it has been recommended that D. deremensis and T. erecta may be used as sinks for the abatement of air pollution at highly polluted sites whereas R. indica and D. caryophyllus can be used as bioindicators.

Status of Air Pollutants after Implementation of CNG in Delhi

Air pollution kills more than 5.9 million people annually, with more than 90 per cent of these deaths in capital city of India, Delhi. For improving the status of air pollution in Delhi, various policies and laws have been implemented. But even after the implementation of CNG, there was no significant change of pollutants (NOx, O 3 , SPM, RSPM & CO) except SO 2 . The objective of our study is whether CNG conversion has impinged on the primary pollutant and tropospheric ozone pollution profile and for the improvement in the quality of air in post CNG period. To carry out the analysis, daily ambient air quality secondary data (Jan 2002-Dec 2009; Source-CPCB) of all the above discussed pollutants were used. For generating own data, NOX and O3 monitoring were carried out at four different sites viz. Site I (Yamuna Biodiversity Park, away from traffic intersection), Site II (Traffic intersection at outside YBP, outer ring road, Gandhi vihar), Site III (Aravalli Biodiversity Park, away from traffic intersection) and Site IV (traffic intersection at outside ABP, ring road, Vasant vihar) during monsoon season (Aug-Sept, 2009). The concentration of ozone was higher at sites which are at traffic intersection (Site II & IV) than those which are away from traffic intersection (Site I & III). The results however, do not indicate an all round improvement in ambient air quality of Delhi. Hence, our short term study suggests that after the implementation of CNG in Delhi there is no remarkable improvement in the status of the pollutants and moreover, the sites which are near to traffic intersection possess high concentration of pollutants than the sites which are away from traffic intersection.

Effect of Bacterial and Fungal Abundance in Soil on the Emission of Carbon Dioxide from Soil in Semi-arid Climate in India

Carbon dioxide concentration in atmosphere is actively increasing since industrial revolution (1800) from 285 ppmv to 378 ppmv in 2005. Carbon dioxide efflux from soil due to floral and faunal respiration in soil, called soil respiration, is the second largest source of increasing concentration of CO2 in atmosphere. Soil respiration produces almost 11 times more carbon dioxide in atmosphere than that produced due to fossil fuel burning [18]. Microorganisms are the most abundant biotic group in soil and huge amount of CO2 is evolved from soil due to bacterial and fungal respiration. The present study investigated soil respiration and distribution of bacteria and fungi in the soil. The study was conducted in semi arid (subtropical) climate around New Delhi in India. Two different sites (Aravali Biodiversity Park and Yamuna Biodiversity Park) with ecologically different soil and vegetation conditions were studied. Three different locations were selected at each site and at each location CO2 efflux and microbial population were measured at three depths, topsoil (0–5 cm depth), midsoil (15–20 cm depth) and Deep soil (40–45 cm depth). Higher soil activity was found at Yamuna Biodiversity Park (YBP) having profuse ground vegetation, sandy soil with high organic matter and moisture content than Aravali Biodiversity Park (ABP) having scares vegetation, rocky area and dry soil with low organic matter content. Higher soil respiration is recorded in the surface and mid soil at YBP than ABP. However the soil respiration rate was slightly more in deep soil at ABP. In most of the cases soil respiration was found increasing from surface soil to deeper soil till 50 cm depth. Rate of soil respiration is highly correlated (R 2 = 0.7) to fungal population. Our study suggests that soil respiration process is a function of bacterial and fungal abundance in the soil. However, fungal population is more responsible for CO2 evolution in atmosphere from soil than bacterial population. Better understanding of soil respiration process can help in reducing CO2 emission and carbon sequestration process.

Microplastics: An Unsafe Pathway from Aquatic Environment to Health—A Review

Waste is considered to be any solid material that is manufactured or processed and then discarded or disposed, ending up either in a terrestrial or an aquatic environment. It is possible to curb the negative effects of waste when it is dumped on land, but as it enters water, its potential impact is unpredictable, as water is a universal solvent with an ability to dissolve and hoard contaminants. Contaminants can be organic and inorganic, which determine their associated toxicity. Various solid wastes such as plastic, glass, metal, rubber, and wood have already polluted available potable water resources. Of all contaminants, plastics are commonly used presently and although they reduce the exploitation of natural resources, they are highly persistent in nature and end up in water bodies in the form of plastic debris. Plastic debris within an aquatic environment can be macro, meso, micro, or nano in size. Larger macro-size particles have been reported to commonly entangle aquatic invertebrates, birds, mammals, and turtles. On the other hand, micro- and nano-size particles form through different fragmentation processes such as photodegradation and microbial degradation, and as a result of other external forces. Micro-sized plastics (<5 mm in diameter) are ubiquitous in water, sediment, and their associated biota. Their smaller size and colorful appearance makes them resemble food for aquatic organisms, and hence they bioaccumulate easily. Also, additives used during plastic synthesis are released into the aquatic and terrestrial environments in the form of toxic chemicals. Among anthropogenic “cosmetics,” toothpaste is considered to be one of the major contributors to microplastics pollution. It uses micro-sized beads for exfoliation. Research on microplastics is rapidly increasing worldwide, and microplastics have already been tagged as an alarming threat, but there exists a knowledge gap on actual concentrations, their impacts, and their sources. This review addresses possible types and sources of microplastics, their bioavailability, and an analysis of their fate, or potential impact, on aquatic environments.

Establishing Correlation Between Abiotic Stress and Isoprene Emission of Selected Plant Species

The atmospheric hydrocarbon budget influenced by a vast range of volatile organic compounds (VOCs) is both anthropogenic and biogenic in origin. Evolution of plant VOCs is a complex process affected by interactions of plants with biotic and abiotic factors in constantly changing environment but their functional role is still a matter of speculation. Isoprene (2-methyl 1,3-butadiene), a five-carbon hydrocarbon, is emitted from the leaves of many plant species. In the present study, isoprene emission potential of two urban plant species (Dalbergia sissoo and Nerium oleander) were measured using branch enclosure method at different selected sites on the basis of proximity to traffic density. In order to find out the dependence of isoprene emission with abiotic factors (temperature and photosynthetic active radiation PAR), regression analysis has been performed. In the case of Dalbergia sp. high temperature and PAR promote high isoprene emission during summer months. Thus, positive linear relationship gives the best fit between temperature, PAR, and isoprene emission rate during summer season as compared to other seasons, whereas in the case of Nerium sp., no such appropriate relationship was obtained. The study concludes that Dalbergia sissoo comes under high isoprene emission category, while Nerium oleander comes under BDL (below detection limit) variety. For any greenbelt development program, it is very important to select the type of plant species to be planted. The present small study reflects that Nerium oleander should be planted in the outskirts of selected areas and that planting of Dalbergia sissoo should be done on low scale so that the air remains clean and indirect production of tropospheric ozone, aerosol production will be minimized.

Temporal Mount in Air Pollutants Allied with Religious Fiesta: Diwali, Festival of Lights

India being a secular country is bound by many religious and cultural activities. Diwali or Deepawali is one of the major festivals which is celebrated with great heartiness by bursting firecrackers (both aerial and land). “Firework displays in Delhi, the capital of India, are known to be grand and extensive, perhaps owing to the relative affluence of the city’s population” (Sarkar et al. 2010). Fireworks are one of the most unusual sources of anthropogenic pollution in atmosphere; although short-lived, these events are responsible for high concentrations of particles and gases in the atmosphere. To recognize the severity of such episodes on air quality, we undertook a study analyzing the pollutant data the day before, on the eve of Diwali, and the day after the fiesta, for 6 consecutive years, 2010–2015. Further, we compare the results by taking a reference month, the month before the celebration. Pollutant data for particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), and ozone (O3) was collected from real-time SAFAR (MoES) monitoring station installed at Sports Stadium, University of Delhi, Delhi. To understand the health impacts and dispersion of pollutants, AQHI and Hysplit model was also computed. On average on the day of the festival the concentration of PM10 and PM2.5 was found to be 6.5 and 6.8 times higher respectively in comparison to permissible limit over period of 6 years. Similarly, NO2 and O3 were found crossing the permissible limit by 1.6 and 1.2 times in the year 2013. Interestingly, in the year 2011 and 2014 restricted dispersion was observed, with winds moving back towards Delhi, which might have had a role in concentrating the pollution. The short-term exposure of these pollutants beyond the permissible limits can increase the probability of acute health effects, especially for the vulnerable group of population. Therefore, it is of utmost necessity to monitor the outburst of pollution during such events. Although regulating or restricting the festival would be socially unacceptable, adapting to cleaner, more environmental friendly ways to celebrate the festival is the need of the hour.

Ranking of BTEX with Respect to Ozone Formation by Development of Ozone Reactivity Scale

The high concentration of ground-level ozone is a serious problem in many areas. Ozone formation is non-linear process and is produced from the photochemical interactions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx) in the troposphere. Generally, MIR (Maximum Incremental Reactivity) scale is one of the popular ones in the assessment of ozone formation potential of various VOC compounds. In this study, we have taken this scale into consideration for analysing the ranking of benzene, toluene, ethylbenzene and xylene (BTEX) at selected sites which are divided on the basis of near to traffic intersection and less vegetation (Site I) and away from traffic intersection with dense vegetation (Site II) during winter season (Nov’10–Feb’11). The results showed that the average concentration of ozone was found to be higher at Site I than Site II. As per MIR scale, irrespective of site and month, xylenes (m-/p-xylene plus o-xylene) are the most dominant contributor to ozone formation amongst BTEX. Toluene is the second largest contributor to ozone formation. Amongst all, ozone formation potential of benzene is least but it is the most hazardous and carcinogenic species amongst BTEX. Thus, this scale is very useful for examining the relative importance of VOC compounds for their role in photochemical smog formation including production of ozone.