R. Bhushan et al., Concentrations and burial fluxes of organic and inorganic carbon on the eastern margins of the Arabian Sea, MARINE GEOL, 178(1-4), 2001, pp. 95-113
Eleven sediment cores were analysed from the continental margins of the eas
tern Arabian Sea (22 degreesN to similar to 10 degreesN) for organic carbon
(C-org), nitrogen (N) and CaCO3 contents. Similar variations are observed
in both lateral and the vertical (< 1.6 m) distribution of the concentratio
ns of C-org, N and CaCO3 ranging from <similar to>1-6%, 0.10-0.82% and simi
lar to 10-81%, respectively. The C/N ratios, varying from 6-15 averaging 9.
3, indicate that C-org is mostly of marine origin. The burial fluxes (BF) o
f C-org and CaCO3 are in the range of 0.8-21 and 39-194 g m(-2) a(-1), resp
ectively. The upper limits of burial efficiency (BE) for CaCO3 (compared to
its rain rate of 25 g m(-2) a(-1) in sediment trap at a depth of 2500 m fr
om a nearby region) ranges from 39 to 780%. BE values greater than 100% in
the northern (> 15 degreesN) could be most likely due to redeposition of ma
terial from shelf and slope regions as well as influx of detrital carbonate
s from coastal areas. The inverse correlation observed in C-org and CaCO3 d
istribution is indicative of post-depositional effects due to sulphate redu
ction associated processes. This can lead to dissolution of CaCO3 and a bet
ter preservation of C-org due to faster deposition rate and higher detrital
(clay) content. The BF and paleoproductivity calculated using the transfer
function of Samthein et al. [Miner. Soc. Spec. Publ. 64 (1992) 411] show i
ncreasing trend between similar to 10 and similar to2 ka with a significant
periodicity of 3000 a corresponding to that observed for monsoon-induced p
roductivity. (C) 2001 Elsevier Science B.V. All rights reserved.