Phosphorus and its solubility in aerosols from continental and marine sources in the sea areas near China: Results from a 40-day cruise mission in late spring

Abstract

Accurate assessments of soluble phosphorus (P) in aerosol particles are essential to understand the atmospheric nutrients supply to the marine ecosystem. We quantified total P (TP) and dissolved P (DP) in the aerosol particles collected in the sea areas near China in a cruise mission from May 1 to June 11, 2016. The overall concentrations of TP and DP were 3.5–99.9 ng m−3 and 2.5–27.0 ng m−3, respectively. When the air originating from the desert areas, TP and DP were 28.7–99.9 ng m−3 and 10.8–27.0 ng m−3, respectively, and P solubility was 24.1–54.6 %. When the air influenced mainly by anthropogenic emissions from eastern China, TP and DP were 11.7–12.3 ng m−3 and 5.7–6.3 ng m−3, respectively, and P solubility was 46.0–53.7 %. More than half of the TP and more than 70 % of the DP were from pyrogenic particles, with a considerable DP converted via aerosol acidification after the particles met humid marine air. On average, aerosol acidification promoted the fractional solubility of dissolved inorganic P (DIP) to TP from 22 % to 43 %. When the air originating from the marine areas, TP and DP were 3.5–22.0 ng m−3 and 2.5–8.4 ng m−3, respectively, and P solubility was 34.6–93.6 %. About one-third of the DP was from biological emissions in organic forms (DOP), leading to higher solubility than in the particles from continental sources. These results reveal the dominance of inorganic P in TP and DP from the desert and anthropogenic mineral dust and the significant contribution of organic P from marine sources. The results also indicate the necessity to treat aerosol P carefully according to different sources of the aerosol particles and atmospheric processes the particles experience in assessing aerosol P input to seawater.