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11.
Ajay Kumar Sabyasachi Rout R. K. Singhal P. M. Ravi R. M. Tripathi 《Journal of Coastal Conservation》2016,20(4):289-297
Bio-diffusion mixing rates (Db) were estimated from depth profiles of excess 210Pb and 137Cs in three sediment cores collected from Mumbai Harbour Bay (MHB) using a steady state vertical advection - diffusion model. The mean of 210Pb and 137Cs derived Db values along the studied area were obtained to be about 23 and 36 cm2y?1 respectively. These derived values were within the range of literature values reported for other equivalent environment internationally. The relatively higher Db values for 137Cs profiles demonstrated that particles have diffused more intensely within the surface layer of sediments over 1 year. Conversely, low Db values for 210Pb indicate slow mixing rates in the sediment profile which might be resulted from low 210Pb flux and diffusion of 222Rn to the seafloor. The significant differences between 210Pb and 137Cs derived Db values among cores indicate that there appeared to be as regional differences in sediment properties and local variability in the intensity of seafloor mixing. Furthermore, Db values also depend on differences in characteristic time and depth scales of radionuclides in cores, benthic fauna abundances, organic carbon flux to the sediments and primary production in overlying surface waters. Comparison of 210Pb derived Db values with those calculated from 137Cs distributions reveals better agreement for core 2 than core 1 and 3. The agreement may be fortuitous because 137Cs appears significantly deeper than 210Pb in all cores. It was also observed that Db values increases as sediment accumulation rate increases for both radionuclide. 相似文献
12.
Tofan Kumar Rout R. E. Masto L. C. Ram Joshy George Pratap Kumar Padhy 《Environmental geochemistry and health》2013,35(3):347-356
Jharia (India) a coal mining town has been affected by the consequences of mining and associated activities. Samples of outdoor fallen dust were collected at different locations of Jharia covering four different zones: commercial, petrol pump, high traffic, and residential areas. The dust samples were analysed for different trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, and Zn). The highest concentration of the elements in the dust samples are Mn (658 mg/kg), Zn (163.6 mg/kg), Cr (75.4 mg/kg), Pb (67.8 mg/kg), Ni (66 mg/kg), Cu (56.8 mg/kg), Co (16.9 mg/kg), As (4.1 mg/kg), and Cd (0.78 mg/kg). The concentration of selenium was below detection limit. Except Cd, contents of all the other elements in the dust samples were significantly lower in the residential area. High amount of Ni (145 mg/kg) and Pb (102 mg/kg) was observed in the high traffic and petrol pump areas, respectively. The exposure risk assessment strategies are helpful in predicting the potential health risk of the trace elements in the street dust. Selected receptors for risk assessment were infants, toddlers, children, teens, and adults. The calculated hazard quotient (HQ) for lifetime exposure was <1.0 for all the elements studied, indicating no risks from these elements for adults Among the receptors, toddlers were found to be more vulnerable, with HQ for Co, Cr, and Pb > 0.1. The finding predicts potential health risk to toddlers and children. 相似文献