Photochemical production of low-molecular-weight carbonyl compounds in seawater and surface microlayer and their air-sea exchange

摘要: Abstract Coastal and oceanic surface microlayer samples were collected using a stainless steel screen, along with subsurface bulk seawater, analyzed for low-molecular-weight (LMW) carbonyl compounds, including formaldehyde, acetaldehyde, propanal, glyoxal, methylglyoxal, glyoxylic acid pyruvic acid. The enrichment factor in compared to corresponding seawater ranged from 1.2 21. A time-series measurement at coastal site showed strong diurnal variations concentrations of the LMW compounds factor, maxima early afternoon minima morning. Exposure sunlight resulted higher yields these than by 1.1–25, suggesting that photoproduction rate accounts majority observed samples. Potential sinks include biological uptake mixing. Air-sea exchange may be source soluble sink less compounds. alter their net air-sea direction e.g., ocean as potential atmospheric acetaldehyde acetone. residence times estimated on order tens seconds minutes modified two-layer model. However, maintain time should ~ 1 hour. This prolonged due organic (‘organic film’) which inhibited molecular transfer into out microlayer. deviated behavior model prediction also changes apparent partition coefficients species result thier physical chemical interactions matrix