Figure 1.

(a) Location of Arabian Sea sampling station (indicated by the star; lat 21°55', long 63°10′), just outside the region containing a quasi-permanent secondary nitrite (NO₂⁻) maximum (Revsbech et al., 2009). Persian Gulf Water (PGW) and to a much lesser extent, Red Sea Water (RSW), influence the OMZ at our study site. (b) Hydrographic characteristics of the water column at our sampling station as recorded from the CTD sensors, and depths where SPM sampling was performed using an in situ pump.