DISTRIBUTION OF NITROUS-OXIDE AND METHANE IN THE ARABIAN SEA

Citation
S. Lal et al., DISTRIBUTION OF NITROUS-OXIDE AND METHANE IN THE ARABIAN SEA, Current Science, 71(11), 1996, pp. 894-899
Citations number
19
Categorie Soggetti
Multidisciplinary Sciences
Journal title
ISSN journal
00113891
Volume
71
Issue
11
Year of publication
1996
Pages
894 - 899
Database
ISI
SICI code
0011-3891(1996)71:11<894:DONAMI>2.0.ZU;2-6
Abstract
Measurements of the two important biogenic gases N2O and CH4 have been made both in the water column and in air of the Arabian sea during Ap ril-May 1994 and February-March 1995, as part of the JGOFS (India) pro gramme, The average abundances of N2O and CH4 in the air are 313 +/- 7 ppbv and 1.69 +/- 0.05 ppmv respectively. During both the periods, th e vertical profiles of N2O in the water column show a double peak stru cture with the dominant peak in the 500-1000 m depth region with conce ntrations of 70-80 nmol, The entire water column is supersaturated wit h respect to N2O and in the major peak region it is supersaturated by as much as 600-800%, suggesting this region of the Arabian sea to be a n important reservoir of N2O. During February-March 1995, sea-air flux of N2O is calculated to be about 0.26 pg cm(-2) s(-1), while the flux calculated for April-May 1994 is not significantly different from zer o, Methane concentrations were measured only down to 400 m depth, Its distribution shows a peak concentration of 6-8 nmol in the 100-200 m d epth region, Supersaturation (up to 200-400% at the peak) is found for CH4 in most of the profiles. Average sea-air flux of methane during A pril-May 1994 and February-March 1995 is 0.0001 and 0.033 pg cm(-2) s( -1), respectively.