3 years ago

Wavelength- and Temperature-Dependent Apparent Quantum Yields for Photochemical Production of Carbonyl Compounds in the North Pacific Ocean

Wavelength-
and Temperature-Dependent Apparent Quantum
Yields for Photochemical Production of Carbonyl Compounds in the North Pacific Ocean
managing.editor@est.acs.org (American Chemical Society)
Photolysis of dissolved organic matter is the main source of carbonyl compounds in sunlit seawater, but rates and photoefficiences are poorly constrained. Wavelength- and temperature-dependent apparent quantum yields (AQYs) were determined for photochemical production of acetaldehyde, glyoxal, and methylglyoxal in North Pacific Ocean seawater. Wavelength-dependent AQYs at 20 °C decreased exponentially with increasing wavelength between 290 and 380 nm, from 1.29 × 10–4 to 4.12 × 10–6, 2.52 × 10–5 to 6.89 × 10–7, and 4.37 × 10–6 to 1.25 × 10–7 mol (mol quanta)−1 for acetaldehyde, glyoxal, and methylglyoxal, respectively. AQYs decreased after 6 h irradiation at 310 nm, possibly due to depletion of photochemical precursors or carbonyl photolysis. Average activation energies (95% CI) for photochemical production at 320 nm were 9.31 (±9.3), 26.0 (±7.5), and 34.7 (±12.8) kJ mol–1 for acetaldehyde, glyoxal, and methylglyoxal, respectively. The peak response for photochemical production rates in surface seawater was ∼325 nm, with ∼30% contribution from UV-B and ∼70% from UV-A. Computed noontime wavelength-integrated photoproduction rates were 0.5–0.8, 0.04–0.2, and 0.03–0.06 nmol L–1 h–1 for acetaldehyde, glyoxal, and methylglyoxal, respectively, under cloudless conditions in August. Results can be used to determine regional-scale photochemical production rates for these compounds in the surface ocean.

Publisher URL: http://dx.doi.org/10.1021/acs.est.7b05462

DOI: 10.1021/acs.est.7b05462

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.