posted on 2020-03-12, 12:06authored byPhoebe Zito, David C. Podgorski, Tessa Bartges, François Guillemette, J. Alan Roebuck, Robert G. M. Spencer, Ryan P. Rodgers, Matthew A. Tarr
Spilled
oil is highly susceptible to sunlight-induced transformations,
both as films on the surface of water and material dissolved or dispersed
in the water column. We utilized ultrahigh-resolution mass spectrometry
and optical spectroscopy to understand shifts in oil photoproduct
distributions as a function of photo-oxygenation. Oxygenation of oil
produces compounds that have increased polarity, resulting in greater
partitioning to the oil–water interface and eventually greater
partitioning into the aqueous phase. Such partitioning was shown to
be dependent on the carbon number and oxygen content of the photoproducts,
providing an empirical basis for predicting the partitioning of oil
photodegradation products between the oil phase, the interfacial region,
and into the aqueous phase to form petroleum-derived dissolved organic
matter. While such photochemical transformations have been predicted
for many years, there has not been direct evidence previously for
the photodissolution process. Furthermore, the relationship of carbon
number and oxygen content with progression from the oil phase to the
interfacial phase to the aqueous phase has not been demonstrated.
This paper details this progression and observable properties that
can be used to understand oil behavior after a spill during sunlight
exposure, thus providing greater predictability of oil fate, transport,
impact, and effective remediation strategies.