Remote Sensing of Dispersed Oil Pollution in the Ocean—The Role of Chlorophyll Concentration

Abstract

In the contrary to surface oil slicks, dispersed oil pollution is not yet detected or monitored on regular basis. The possible range of changes of the local optical properties of seawater caused by the occurrence of dispersed oil, as well as the dependencies of changes on various physical and environmental factors, can be estimated using simulation techniques. Two models were combined to examine the influence of oceanic water type on the visibility of dispersed oil: the Monte Carlo radiative transfer model and the Lorenz–Mie model for spherical oil droplets suspended in seawater. Remote sensing reflectance, Rrs, was compared for natural ocean water models representing oligotrophic, mesotrophic and eutrophic environments (characterized by chlorophyll-a concentrations of 0.1, 1 and 10 mg/m3, respectively) and polluted by three different kinds of oils: biodiesel, lubricant oil and crude oil. We found out that dispersed oil usually increases Rrs values for all types of seawater, with the highest effect for the oligotrophic ocean. In the clearest studied waters, the absolute values of Rrs increased 2–6 times after simulated dispersed oil pollution, while Rrs band ratios routinely applied in bio-optical models decreased up to 80%. The color index, CI, was nearly double reduced by dispersed biodiesel BD and lubricant oil CL, but more than doubled by crude oil FL.

Influence of Dispersed Oil on the Remote Sensing Reflectance—Field Experiment in the Baltic Sea

“…The main conclusion of these studies was that at even as low a concentration as 1 ppm of oil, droplets can cause significant changes to the R rs . This effect was dependent on oil type [65], droplet size distribution [62], and seawater optical properties [61], as well as wind conditions and sensor geometry [66]. In this study, we took a step forward from modeling to in situ experiment in a unique attempt to measure the R rs of dispersed oil pollution in open sea conditions.…”

“…Obtained stable concentrated oil-in-water dispersions, pictured in Figure 6, were stored in glass bottles at room temperature. Samples of mechanically dispersed oils were prepared onboard the ship 12-18 h prior to measurement, according to the procedure described in [44,60,61]. Obtained stable concentrated oil-in-water dispersions, pictured in Figure 6, were stored in glass bottles at room temperature.…”

“…We collected a minimum of 100 scans for each measurement and averaged three repetitions for each sample of dispersed oil to minimize the heterogeneity uncertainties. Samples of mechanically dispersed oils were prepared onboard the ship 12-18 h prior to measurement, according to the procedure described in [44,60,61]. Obtained stable concentrated oil-in-water dispersions, pictured in Figure 6, were stored in glass bottles at room temperature.…”

Fluorometric Detection of Oil Traces in a Sea Water Column

“…However, despite its many advantages, remote sensing has limitations; an example of this is the detection and identification of oil pollutants over the vertical dimension of the water column, when oil is not visible on the sea surface. Considering future remote technologies, this issue is developed by modeling the radiance reflectance of the water masses [17][18][19][20][21].…”

Acute inhibition of bacterial growth in coastal seawater amended with crude oils with varied photoreactivities

“…Parameters affecting bacterial production when oil is present can also include specific capacities of bacterial taxa to degrade various hydrocarbon species (Head et al, 2006;Vergeynst et al, 2019;Bacosa et al, 2020a), microbial production of biosurfactants that facilitate bioavailability of petroleum molecules (Matvyeyeva et al, 2014), the relative abundance of nitrate-reducers among microbial community members (Melkonian et al, 2021), and the trophic state of the seawater upon oil introduction (Haule and Freda, 2021). Water temperature, nutrient availability, solar exposure, and oxygen affect microbial activity (Scofield et al, 2015;Hutchins and Fu, 2017;Cavicchioli et al, 2019;Robinson, 2019) altering the microbial degradation of crude oil components (Atlas and Hazen, 2011;Gregson et al, 2021).…”