Estimation of radon exhalation rate, natural radioactivity and radiation doses in fly ash samples from Durgapur thermal power plant, West Bengal, India

Coal and its by products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent emission to the atmosphere cause the re-distribution of toxic trace elements in the environment. Due to considerable economic and environmental importance and diverse uses, the collected fly ash has become a subject of worldwide interest in recent years. In the present study, radon exhalation rate and the activity concentration of (238)U, (232)Th and (40)K radionuclides in fly ash samples from Durgapur thermal power plant (WB) have been measured by "Sealed Can technique" using LR-115 type II detectors and a low level NaI (Tl) based gamma ray spectrometer, respectively. Radon exhalation rate varied from 360.0 to 470.0 mBq m(-2)h(-1) with an average value of 406.8 mBq m(-2)h(-1). Activity concentrations of (238)U ranged from 84.8 to 126.4 Bq kg(-1) with an average value of 99.3Bqkg(-1), (232)Th ranged from 98.1 to 140.5 Bq kg(-1) with an average value of 112.9 Bq kg(-1) and (40)K ranged from 267.1 to 364.9 Bq kg(-1) with an average value of 308.9 Bq kg(-1). Radium equivalent activity obtained from activity concentrations is found to vary from 256.5 to 352.8 Bq kg(-1) with an average value of 282.5 Bq kg(-1). Absorbed gamma dose rates due to the presence of (238)U, (232)Th and (40)K in fly ash samples vary in the range 115.3-158.5 nGy h(-1) with an average value of 126.4 nGy h(-1). While the external annual effective dose rate varies from 0.14 to 0.19 mSv y(-1) with an average value of 0.15 mSv y(-1), effective dose equivalent estimated from exhalation rate varies from 42.5 to 55.2 microSv y(-1) with an average value of 47.8 microSv y(-1). Values of external hazard index H(ex) for the fly ash samples studied in this work range from 0.69 to 0.96 with a mean value of 0.77.     

Irrigation with domestic wastewater: responses on growth and yield of ladyfinger Abelmoschus esculentus and on soil nutrients

Domestic wastewater is generated continuously and in large quantities. It can serve as an alternative water nutrient source for irrigation. In the present study Abelmoschus esculentus L. (Ladyfinger) was irrigated using untreated wastewater (T1), treated wastewater (T2) and rainwater (T3) in pot experiments. The effect was seen on nutrient fortication, growth and yield of the plant and the nutrient status of the soil. Additionally the build up of Cr, Cu and Zn from the irrigation water were anlayzed in different parts of the plant biomass and in the soil. The sapling survival rate was found to be 87% in T1 followed by T2 and T3. Root shoot ratio under different treatments was found in the order T3 (0.46) >T2 (0.35) >T1 (0.31). The chlorophyll a, b and carotene content in the leaves (mg g(-1)) was found to be 6.3, 0.5, 0.9 under T1, 4.8, 0.4, 0.8 under T2 and 3.2, 0.3, 0.5 under T3 respectively and all the three varied in the order T1>T2>T3. The same trend was found in case of total dry matter (g) T1 (6.3) >T2 (3.7) >T3 (2.3) at p < or = 0.05. There was a considerable increase in nutrients in the soil under T1 and T2 as compared to T3 after final harvest. The organic matter (%), NO3-N and PO4(3-) (mg kg(-1)) content post harvest soil was found to be 3.4, 71, 90 under T1 and 2.9, 52, 63 under T2 respectively. Also, there was an increase in cations Na, K, Ca and Mg in the soil irrigated with T1 and T2 after the final harvest. Thus irrigation with wastewater generally increased soil fertility. Only a small percentage of the heavy metal was bioaccumulated by the plant parts from the irrigation water. There was hardly any metal accumulation in fruits. Bulk of the metal ions remained in the soil.     

Role of bioinoculants and organic fertilizers in fodder production and quality of leguminous tree species

The comparative effect of dual inoculation of native N fixer (Rhizobium) and AM fungi consortia with different organic fertilizers (vermicompost and farm yard manure) on fodder production and quality of two leguminous tree species (Leucaena leucocephala (Lam) de. Wit. and Sesbania sesban (L.) Merr.) in silvopastoral system and their impact on the fodder production of un-inoculated Panicum maximum Jacq. under cut and carry system. After three years of plantation maximum tree survival was in L. leucocephala in all the treatments in comparison to S. sesban while fodder production was more in S. sesban for initial two years and in third year it accelerated in L. leucocephala. Dual inoculation with vermicompost significantly improved fodder production, fodder quality and rhizosphere microflora in L. leucocephala but in S. sesban dual inoculation was at par with single inoculation of N fixer, AM fungi and control (without inoculation). The grass production was higher with L. leucocephala for two years while in third year it was more with S. sesban. The association of Rhizobium with AM fungi in L. leucocephala was better than in S. sesban.     

Effect of pH and salinity on pathogenicity of Flavobacterium columnare and Myxobacterium sp. in Indian cat fish, Clarias batrachus (Linn.) and Heteropneustes fossilis (Bloch.)

Flavobacterium columnare (FC) and Myxobacterium sp. recorded persistently associated in fish hatchery and culture system of Himalayan and Sub - Himalayan regions were found to be pathogenic. The pH and salinity played a significant role on the pathogenicity of these potent pathogens in case of Clarias batrachus and Heteropneustes fossilis. LD50 value of FC was 10(4.5) CFU in both the fishes and those of Myxobacterium sp it was 10(6) CFU ml(-1) fish(-1). Fish challenged with F. columnare and Myxobacterium sp. (@ 0.2 ml fish(-1)) individually consisting 10(5-6) cfu ml(-1) exhibited explicit symptoms of columnaris disease and marked with ulceration and saddle back lesion on the dorsal side of body. Maximum reisolation of inoculated bacteria was recorded at pH 7.0 and 7.5 and at 0.0-0.5 (F. columnare) and 0.0-1.0% (Myxobacterium sp.) salinity. Foregoing results elucidated that F. columnare was more sensitive to salinity in comparison to Myxobacterium sp. and their pathogenicity significantly (p<0.05) depends on the salinity and pH that might be one of the physical factors to control their proliferation.     

Non-thermal plasmas for disease control and abiotic stress management in plants

Environmental Chemistry Letters - Climate change is predicted to cause severe loss in agricultural production by increasing disease epidemics and intensifying&nbsp;abiotic stresses. Therefore,...     

Physico-chemical characteristics of pulverized coals and their interrelations—a spontaneous combustion and explosion perspective

Environmental Science and Pollution Research - Characteristics of pulverized coals have significant influence on the spontaneous combustion and explosion processes. This paper presents an...     

Property-enhanced paraffin-based composite phase change material for thermal energy storage: a review

Environmental Science and Pollution Research - Research on phase change material (PCM) for thermal energy storage is playing a significant role in energy management industry. However, some hurdles...     

Integrated process approach for degradation of p-cresol pollutant under photocatalytic reactor using activated carbon/TiO2 nanocomposite: application in wastewater treatment

Environmental Science and Pollution Research - Over the years, biodegradation has been an effective technique for waste water treatment; however, it has its own limitations. In order to achieve a...     

Designing hydro-energy led economic growth for pollution abatement: evidence from BRICS

Environmental Science and Pollution Research - Overutilized hydro-energy production through non-sustainable mode is detrimental for both the economy and the environment. Intermittent consumption of...     

Fabrication of ZnO–SnO2 nanocomposite and its photocatalytic activity for enhanced degradation of Biebrich scarlet

Environmental Science and Pollution Research - The n–n-type ZnO–SnO2 nanocomposite was fabricated using malic acid following a simple one-pot co-precipitation method. The fabricated...