Inventory, fluxes and residence times from the depth profiles of naturally occurring ^sup 210^Pb in marine sediments of Mumbai Harbor Bay

• Published in: Environmental earth sciences Vol. 73; no. 8; p. 4019
• Main Authors: Kumar, Ajay, Rout, Sabyasachi, Karpe, Rupali, Mishra, Manish Kumar, Narayanan, Usha, Singhal, Rakesh Kumar, Ravi, Pazhayath Mana, Tripathi, Raj Mangal
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01-04-2015
• Subjects: Clay; Cores; Harbors; Marine sediments; Measurement; Sedimentation; Sediments; Studies; Mumbai India; India
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-014-3687-6

Measurements of the vertical concentration profile of deposited ^sup 210^Pb and its parent (^sup 226^Ra) in cores of recent marine sediment of Mumbai Harbor Bay (MHB) were made to determine the various depth distribution parameters (sedimentation rate, age of sediment, total inventory, fluxes, residence times, scavenging rate, linear attenuation coefficient and relaxation mass depth). Overall, the profile distributions of ^sup 226^Ra and ^sup 210^Pb showed a decreasing trend with increasing the depth. The mean of sedimentation rate in the studied area was obtained to be about 0.76 cm year^sup -1^ which corresponds to average age of sediment of about 56 years. The average total deposited ^sup 210^Pb for the studied sediment profile was 9.68 k Bq m^sup -2^ and correspondingly the average value of fluxes of total ^sup 210^Pb and excess ^sup 210^Pb (atmospheric flux) were 0.59 and 0.32 k Bq m^sup -2^year^sup -1^, respectively. The residence time of ^sup 210^Pb was in the range of 26-226 years throughout the sediment profile and showed generally an increasing trend from top to bottom. The mean relaxation mass depth (h^sub 0^) derived from the depth profile of ^sup 210^Pb at the studied area was about 190 kg m^sup -2^. The negative association between clay content of cores and the h^sub 0^ of ^sup 210^Pb indicates that as the clay content increases, the penetration depth of deposited ^sup 210^Pb in sediment profile decreases.