He was the chief Indian scientist of LOHAFEX, an ocean iron fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany.
His research focussed on biologically mediated chemical transformations in the oxygen minimum zone (OMZ) of the Arabian Sea, which were largely unknown at that time.
He provided conclusive evidence for large-scale denitrification (microbial reduction of nitrate to N2 and N2O) in the water column, demarcated its spatial extent and determined its temporal variability.
His results revealed that in contrast with the eastern Pacific, zones of highest primary production and most intense denitrification are geographically separated in the northern Indian Ocean.
This decoupling was also shown to be reflected by respiration rates that were found to be maximal within the OMZ, and also too high to be supported by organic matter supplied by particles sinking from the surface layer.
As a part of his pioneering efforts to investigate the impacts of global change on marine bio-geochemistry of the northern Indian Ocean, Naqvi carried out extensive work on greenhouse gases [carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4)] both in the open-ocean and seasonally-occurring coastal hypoxic zone.
The coastal low-oxygen zone, the largest of its kind in the world, has been found to have intensified in recent years, affecting living resources and providing feedback to global change.
Thus, it has been shown for the first time that human activities are causing an increase in oceanic emissions of N2O, and the efflux of this potent greenhouse gas from the Arabian Sea is globally significant, unlike those of CO2 and CH4.
This phenomenon, widely prevalent in the Southern Ocean and equatorial Pacific, has been discovered for the first time in the western Arabian Sea, significantly affecting regional biogeochemistry, including the anomalous location of the OMZ.
Observations in a large number of dams revealed relatively moderate eutrophication, with anoxic conditions prevailing in the lypolimnia during summer stratification with an apparent loss of fixed nitrogen in most reservoirs.
He has been actively involved with planning and implementation of several ocean-related projects of International Geosphere-Biosphere Programme (IGBP) and Scientific Committee on Ocean Research (SCOR).