Aerosolization of Crude Oil‐Dispersant Slicks Due to Bubble Bursting

Abstract

Bubble bursting is a primary source of marine aerosols, yet little is known about particle emissions due to the bubble bursting in slicks containing oil‐dispersant mixtures. In this study, bubbles with mode sizes of 86 μm (denoted as small), 178 μm (medium), and 595 μm (large) are injected into a seawater column covered by slicks of crude oil, pure dispersant, and dispersant premixed with oil at a ratio of 1:25. The aerosol size distributions are monitored in the 0.5‐ to 20‐μm and 10‐ to 380‐nm ranges both in clean and ambient air environments. In ambient air, a tenfold increase in submicron particle concentration occurs when large bubbles burst on slicks of 500‐μm dispersant premixed with oil at a ratio of 1:25 oil or 50‐μm pure dispersant. Yet, in multiple tests performed at different ambient particle concentrations, the elevated size distributions persistently maintain the same shape as that of the ambient air. In contrast, smaller bubbles and tests not involving dispersants do not cause such an increase. Nanodroplets are also generated by large bubbles in particle‐free air, but their concentrations are much lower. All plumes generate micron‐sized aerosols, but trends vary. For the same contaminant, the microdroplet concentration decreases with increasing slick thickness. Particularly striking is a reduction of 2 orders of magnitude in the microdroplet concentration when medium and small bubbles burst on 500‐μm crude oil slicks. Chemical analysis of air and particulates collected from filters sampling the particles confirms the presence of airborne oil above the slicks.

Compound jetting from bubble bursting at an air-oil-water interface

“…Our findings demonstrate a distinct transport mechanism related to dynamics of the bubble bursting jetting at a compound interface. Although previous studies have reported evidence of oily aerosol generation by bubble bursting at a contaminated surface 44,45 , only film droplets are considered to be responsible for the dispersion of the insoluble surface contaminants, including bacteria and aliphatic-rich hydrophobic organic species in the surface microlayer 15,19 , while the jet droplets are believed to only contribute to the transport of more soluble organic species from the underlying seawater 15,46,47 . In this study, we highlight the 12) and ( 13), and the dashed lines represent the scaling laws of Eqs.…”

On the physics of transient ejection from bubble bursting

“…(1954), Blanchard & Woodcock (1957), Veron (2015) and Sampath et al. (2019); disease and pandemic transmission, e.g. Bourouiba (2021)) and in more ‘indulging’ applications (e.g.…”

Physical Transport Processes that Affect the Distribution of Oil in the Gulf of Mexico: Observations and Modeling

“…While the size distributions of marine aerosols have received considerable attention (Veron, 2015), very limited information exists about the process of aerosolization of oil slicks. However, a series of experiments investigated the effect of dispersants on the aerosolization of oil slicks by breaking waves (Afshar-Mohajer et al, 2018), and subsequently, the effect of bubble bursting at an oil-water interface (Sampath et al, 2019;Afshar-Mohajer et al, 2020).…”

“…In an attempt to identify and characterize the mechanisms affecting the generation of nanodroplets, subsequent studies focused on generation of airborne droplets by bursting of rising gas bubbles at the liquid-air interface (Sampath et al, 2019). Bubbles with different size ranges were injected into a seawater column covered by slicks of crude oil, pure dispersant, and a DOR 1:25 dispersant-oil mixture; the sensors mentioned above were used to measure nano-and micro-aerosol size distributions in both clean and ambient air environments.…”