Summary of Abstract Submission

Abstract Submission No. IO50-03-0048PresentationPoster

INORGANIC IONIC CONSTITUENTS OF PM2.5 OVER ARABIAN SEA: RESULTS FROM ONLINE MEASUREMENTS

A K Sudheer*1, R Rengarajan1, R. Bhushan 1, S K Singh1

1 Physical Research Laboratory, Ahmedabad

ABSTRACT :

Atmospheric deposition of nitrogen species onto the surface ocean during continental outflow is an important component of nitrogen cycle in marine environment. Since aerosol chemical composition exhibits large temporal variability over marine atmosphere, extensive measurements of these components are essential for better assessment of atmospheric input. Towards this, real time measurement of water soluble ionic constituents (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+ and Ca2+) of PM2.5 aerosols over Arabian Sea atmospheric boundary layer has been done using Ambient Ion Monitor (AIM) onboard Sagar Sampada during the cruise from March 18 to 13 April 2012. AIM is equipped with a steam jet aerosol collector and two ion chromatographs for simultaneous on-line measurement of cations and anions in PM2.5 with hourly time resolution that enabled to collect about 400 sample data during the cruise. Concentration of NO3- and NH4+ were found 1.03 and 0.8 g m-3, respectively, which are higher compared to earlier reported values using off line filter based measurements on total suspended particulate samples during March-April months. A strong linear relation of NH4- with SO42- indicates existence of fine particulate (NH4)2SO4 and/or NH4HSO4. Deposition flux of inorganic nitrogen calculated based on these measurements is ~ 0.8 mg N m-2 d-1. Cl- and Na+ are significantly correlated with sea-salt proportions and discernible depletion of chloride is not observed.