R.C. Bhangare

Elemental characterization of coal, fly ash, and bottom ash using an energy dispersive X-ray fluorescence technique.

A total of 18 elements viz. Si, Al, Fe, Ca, Mg, K, Na, Sr, V, Zn, Mn, Cr, Cu, Pb, Ni, Co, As and Cd were analyzed in coal, fly ash and bottom ash samples collected across India using an EDXRF technique. Various indices such as element enrichment ratio, enrichment factor (with respect to crustal average) and mineral composition were calculated. Around 95% of mass was reconstructed using the concentration of elements in this study for fly and bottom ash.

Natural radioactivity assessment of a phosphate fertilizer plant area

Abstract Rock phosphate ore processing and disposal of phosphogypsum contribute to enhanced levels of natural radionuclides in the environment. The concentration of naturally occurring radionuclides in soil, rock phosphate and phosphogypsum samples collected around a phosphate fertilizer plant were determined. Also the external background gamma levels were surveyed.238U, 232Th, 226Ra and 40K activities in soil samples were 21–674 Bq/kg, 11–44 Bq/kg, 22–683 Bq/kg and 51–295 Bq/kg respectively. The external background gamma radiation levels in the plant premises were ranging from 48 to 133nGy/h.

Depth profile of major and trace elements in estuarine core sediment using the EDXRF technique.

Distribution and enrichment of elements in sediment are influenced by their texture, mineralogical composition, and physical transport. The vertical concentration profiles of sixteen elements in core sediment samples, namely Na, Mg, Al, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sr, and Pb were measured using the energy dispersive X-ray fluorescence (EDXRF) technique. To check the anthropogenic input various indices (enrichment factor, contamination factor, index of geoaccumulation and pollution load index) were calculated and compared.

External gamma radiation levels and natural radioactivity in soil around a phosphate fertilizer plant at Mumbai

Fertilizers containing phosphate have been used worldwide in increasing quantities in order to replenish natural nutrients, which are being continuously depleted from the soil by virtue of farming activities. Phosphate rocks together with potassium ores and nitrogenous compounds are the main raw materials used for industrial fertilizer production. Rock phosphate ore processing and disposal of phosphogypsum contribute to enhanced levels of natural radionuclides in the environment. The levels of naturally occurring radionuclides such as 238U, 232Th, 226Ra and 40K in soil samples collected around a phosphate fertilizer plant were estimated. Radium equivalent activity, external hazard index and external dose rate due to natural gamma background at various locations around the plant were also measured.

Particle size distributions of ultrafine combustion aerosols generated from household fuels

In the present study, the number size distributions of aerosols generated from five commonly and widely used household fuels namely firewood, coal, dung cake, kerosene stove and LPG stove were investigated using scanning mobility particle sizer (SMPS). Important parameters of PSD such as total number concentration, geometric mean (GM) and geometric standard deviation (GSD) for tested fuels were evaluated and compared. It was found that solid biomass (firewood and dung cake) generates higher particle number concentrations then non–solid fuels i.e. kerosene and LPG stove. For all biomass fuels the number concentrations were in the order of 10 7 particle/cm 3 . The geometric mean diameter was highest for dung cake generated aerosols, while LPG and coal generated aerosol showed lower GM diameter. The geometric mean diameter varied between 48 nm and 152 nm for all tested fuels. The geometric standard deviation values of all tested fuels revealed that in solid biomass combustion, there was more dispersion in aerosol sizes than non–solid fuels. The number concentration emitted by LPG was found to be the lowest among all fuels and the GSD was also the lowest.

Application of 210Po isotope dating for chronological assessment of organochlorine pesticides in estuarine sediment

Abstract In recent years there has been growing concern all over the globe about marine pollution due to persistent organic pollutants. Sediments, which is an important component of marine environment can serve as sorbent or concentrator for these pollutants. In this study, estimation of sedimentation rate using 210Po dating was carried out to study the depth profile of accumulated OCPs in sediments of Thane Creek Mumbai, India. The creek is a triangular mass of brackish water receiving huge municipal and industrial sewage inputs. Spatial distribution of OCPs was assessed in surface grab sediments and depth profiles of HCH and DDT were obtained in different cores. Radiological dating was performed by estimating the 210Po activity by alpha spectrometry, whereas the OCPs determination was carried out using gas chromatography. The total HCH concentration in the surface sediment samples was in the range of 5.6–13.3 ng/g while total DDT concentration in the surface sediment samples was in the range of 3.2–5.5 ng/g. DDT and γ-HCH were the dominant OCPs in sediments from the creek. The sedimentation rate was determined using 210Po activity measurement in different cores of the sediment and was found to be 0.67 cm/y on average. It was observed that the sediments were highly contaminated during the period of 1970–80 just after the green revolution in India. Total DDT was highest in the 1974–1978 layers of the sediments. Total HCH was highest in the 1972–1976 layers at all the locations.

Laser flourimetric analysis of uranium in water from Vishakhapatnam and estimation of health risk

Uranium is a naturally occurring radioactive element that is both radiologically and chemically toxic. The presence of uranium in the aquatic environment is due to the leaching from natural deposits, release in mill tailings, the combustion of coal and other fuels, and the use of phosphate fertilizers that contain uranium. Intake of uranium through air and water is normally low, but in circumstances in which uranium is present in a drinking water source, the majority of intake can be through drinking water route. The uranium concentrations in ground water samples from Vishakhapatnam, India were estimated using laser fluorimetric technique and were observed to range from 0.6 to 12.3 ppb. The laser fluorimetry technique was found to be an excellent tool for direct measurement of uranium concentration in water samples at ultra-trace levels. The annual effective dose, cumulative dose for 70 years and the lifetime excess cancer risk from drinking of this water were calculated. The risks were low averaging only 10.6 × 10 -6 as none of the samples were observed to exceed the WHO recommended uranium concentration limit of 30 ppb.

Depth profiles of lithogenic and anthropogenic mercury in the sediments from Thane Creek,Mumbai,India

Abstract Mercury (Hg) is well known as one of the most toxic elements to man. The coastal environments adjacent to industrial areas are reported to often be contaminated with mercury. Mercury becomes more toxic in the form of methylmercury (Me-Hg) which is converted from inorganic mercury in aqueous systems by microbial activity and can bio-magnify through the food chain. A simple method for the determination of total mercury and methylmercury in sediments was optimized by slightly modifying an old method using the direct mercury analyzer technique. Core sediment samples from Thane Creek, Mumbai, India were collected and analysed for total mercury and methylmercury. The Hg concentration in the creek varied between 0.54 to 16.03 μg g −1 while Me-Hg concentrations ranged between 0.04 to 1.07 μg g −1 . In surface sediment, mercury concentrations ranged from 4.33 μg g −1 to 12.16μg g −1 . Total organic carbon content was found to be around 2 percent in different layers of the sediments. The enrichment factors, which indicate the extent of pollution in sediments, were estimated to range from 26 to 50 at different locations in the creek. Lithogenic and anthropogenic concentrations of mercury in the creek were also determined to compare the impact of anthropogenic and natural sources. Anthropogenic inventories were about 5-70 times more in concentration than the lithogenic in the different core sediments.

Method for determination of radium in seawater using MnO 2 co-precipitation technique

Radium is considered to be a useful tracer for studying various physical processes of seawater. There are several methods for analysis of radium; however, analysis of radium in seawater by those analytical techniques is a tedious job. Thus a new methodology was optimized for analysis of radium in sea water using MnO2 co-precipitation followed by gamma spectrometry. The method produced good yield which ranged from 85–98%. The method is simple and requires less amounts of chemicals and no use of acids. Seawater from different western Indian coastal environments viz. Tarapur, Mumbai and Goa were collected and analysed for 226Ra and 228Ra using this method.

Partitioning behavior of natural radionuclides during combustion of coal in thermal power plants

ABSTRACT Coal-fired power generation produces huge amounts of fly ash and bottom ash of different properties. Coal contains many naturally occurring radionuclides, which on burning are enriched in the ashes; their discharge to the environment may cause significant exposure of the public to this technologically enhanced naturally occurring radioactive material. Most of these nuclides tend to become particle bound and hence are adsorbed on the ash particles. It is thus important to assess the behavior of radionuclides under combustion in the particle phase. To study the behavior of radionuclides in the particle phase, i.e., in combusted coal ashes, radioactivity measurement of coal and ash samples from different power plants was carried out using alpha and γ-ray spectrometry. The activity of 210Po in fly ash ranged from 12.6 to 91.3 Bq kg−1, while the range of activity concentrations of 238U, 226Ra, 232Th, 40K in fly ash were 56.1–133, 44.3–119, 9.3–144, and 34.5–221 Bq kg−1, respectively. Partitioning behavior of the radionuclides, their relative enrichment factors, and effect of particle size on enrichment of the nuclides in fly ash were also studied. Radionuclides were also grouped using their relative enrichment factors, a consequence of their volatile nature. A good correlation between the partitioning behavior, volatility, and relative enrichment factors of the radionuclides was observed in this study. This outcome of the study could be very useful for determining the fate of the radionuclides, from the bulk low-concentration mineral state in coal mines to the high-concentration particle phase of ashes after burning in power plants. This is important since it is the higher concentration of radionuclides in the particle phase that is a potential source of exposure to the public.