On April 20, 2010, an explosion on the Deepwater Horizon caused the oil rig to sink down into the Gulf of Mexico, leaking more than 3 million barrels of crude oil over four months. The spill off the coast of Mississippi was the largest in United States history, and seven years later, the National Resource Damage Assessment (NRDA) is still determining the extent of its contamination.
In the last 50 years, there have been at least 44 such oil spills of more than 10,000 barrels in U.S. waters. Innovations to the response process are ever more imperative to prevent similar damage to the ocean like the kind inflicted by Deepwater Horizon. However, the measures to respond to these unnatural disasters aren't yet able to keep up.
The Coast Guard, which is responsible for overseeing emergency response during these events, currently use three main methods to clean spilled oil. In booming and skimming, boats use large floating booms (essentially a pool noodle with a skirt attached) to contain the spill while a mechanical device sucks oil off the surface. In situ burning uses gelled gasoline to create controlled burns that remove thick layers of oil from the water.

And chemical dispersion requires an aircraft drop one of 18 EPA-approved dispersants that allow the oil to mix into the water column and get broken down by microbes into less harmful compounds.

These techniques are designed to remove oil from the water's surface, but are ineffective if the oil sinks, making efficient detection and a quick response all the more important during cleanup. There are also drastic side effects: controlled burns can release carbon dioxide and other harmful emissions while the residual burned oil on the surface can sink and harm wildlife, and chemical dispersants can be toxic to animals who ingest them.n

Currently, after a spill, the National Oceanic and Atmospheric Administration (NOAA) creates models of the event, assesses shoreline impact, evaluates cleanup technologies, and provides other science-based support to the U.S. Coast Guard. NOAA then uses aerial snapshots and field observations to confirm which areas are affected in order to deploy cleanup measures to the correct places. However, collecting this data takes time and money, and oil patterns change and spread quickly.

Researchers at the Universidade de Vigo in Spain have found a way to detect oil spills that could make the process cheaper, more efficient, and much easier for emergency response teams. Their new technology deploys small sensors in buoys that would be able to remotely monitor small areas of the coastline and quickly detect oil if it enters their area.

This technology relies on fluorescence to identify the presence of oil on the water. Every type of oil has a unique fluorescence spectrum, which allows light sensors to detect spills and determine the type of oil in the water. The sensors use a configuration of four photodiode detectors, each with a different cellophane film filter, to record four distinct signals and detect each of five different types of oil's specific fluorescence spectra from a database.

The spread of the oil spilled by Deepwater Horizon as of May 24, 2010, captured using NASA's Moderate-Resolution Imaging Spectroradiometer on the Terra satellite. NASA

"The four signals proved to be enough to build a specific fingerprint for every oil type used in our study, letting us identify the different types of oil," Jose R. Salgueiro, lead researcher behind the project, said in a press release, "This approach dramatically reduces the cost of the instrument and simplifies contamination testing."

Salgueiro's invention is inexpensive to produce and can be easily placed in a buoy and then left offshore to monitor specific areas indefinitely. By creating a network of these buoys, researchers could map the spread of spills in real time as sensors in different areas confirm the presence of oil. Without needing to rely on costly aircraft surveillance to track spilled oil, respondents could target their cleanup measures to specific areas with greater speed and precision.
Cleaning Up

Detecting the spread of an oil spill means little unless that oil can also be quickly removed from the water. But the cleanup methods most commonly used by the Coast Guard today also cannot save the oil for future use, so spills are both damaging to the environment and wasteful of valuable resources.

To that end, Seth Darling and a team the Argonne National Laboratory in Illinois have introduced a new way to clean up method that can be deployed quickly and reclaim the oil for future reuse.

Darling's team essentially created a system of large sponges that can be dragged across a slick of oil on the water's surface. The sponges, made up of a polyurethane foam coated with a layer of silane molecules, absorb and trap the oil, safely removing it from the water, and can later be wrung out and reused up to 100 times.
The team at Argonne calculated the amount of silane needed to create a chemical balance, which is attractive enough to absorb oil molecules in the water but not so powerful that it wouldn't be able to release the trapped molecules in the correct conditions later.

The sponges were loaded in mesh bags and then dragged behind a crude oil pipe in the lab's first of many tests at the National Oil Spill Research & Renewable Energy Test Facility.

The sponges were able to absorb 90 times their weight in oil before being sent through a wringer to recollect the oil. They were reused several times without losing their capacity, cementing their status as a sustainable new way to clean up after a spill.

"In an ideal world, you would have warehoused collections of this foam sitting near wherever there are offshore operations… or where there's a lot of shipping traffic, or right on rigs… ready to go when the spill happens," Darling recently told New Scientist.
New Frontiers for Oil Spill Response

New technologies that speed up the response may prevent damage to the coastline, and eliminate the toll on marine life and the loss of vital resources. However, there are still several outstanding questions. Further testing needs to be done to determine how large of an area floating sensors would be able to cover or how to best deploy the absorbent sponge using existing resources.

it will likely be a long while before any of them are incorporated on a large scale. But these innovations show great potential for dramatically improving the response process and saving our oceans

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