Unusual Behavior by Tankers Near Brazil Oil Spill

The source of the massive oil spill affecting Brazil remains unclear, but unusual tanker activity raises questions.

For months now, oil has been washing up on the beaches of northeast Brazil. The quantity of oil, the large area affected, and the length of time oil has appeared, have generated international news coverage and concern. Government officials, scientists and non-governmental organizations around the world — including SkyTruth — have been trying to identify the source of the pollution; so far, unsuccessfully. Brazilian researchers have identified a likely location for the origin of the spill based on ocean currents. The oil is a heavy consistency that floats below the surface of the water and Brazilian researchers and government officials have claimed that it is likely from Venezuela, although they haven’t published the chemical analysis data to support this.

Photo 1. Heavy oil has been sullying the beaches of northeastern Brazil since early September. The cause remains elusive. [Photo courtesy tvBrasil via Creative Commons license]

At SkyTruth we have been examining available satellite imagery and evaluating some of the theories put forward on the origin of the spill. We haven’t seen any convincing evidence of oil slicks or sources on the images, and we don’t agree with analyses published by others (here and here) that claim to have solved the mystery. I recently decided to take a look at AIS (Automatic Identification System) ship-tracking data in the region that Brazilian researchers identified to be the likely origin of the spill. When I examined the AIS data, I found some unusual behavior by oil tankers passing through the area. 

AIS is a system in which vessels at sea transmit their location at regular intervals via VHF radio. Initially designed for collision avoidance, this location data is also picked up by satellites and provides a global record of vessel movements. I was aided by Global Fishing Watch’s automated modeling of AIS tracks, developed by data scientist Nate Miller, which identifies loitering events, that is, locations where vessels have essentially come to a stop, and are drifting out at sea. Tankers and cargo ships normally maintain a relatively constant transit speed as they are moving from their point of origin to their destination port. Ships may stop out at sea for a number of reasons, including engine problems, waiting for entry authorization at a port, or even at-sea transfers of cargo or refueling. But spending more than 24 hours adrift at sea represents a financial loss for a tanker and would suggest unusual circumstances.

Of hundreds of tankers that moved through the area in the months before the oil was reported, a handful stood out for having lengthy loitering events near the likely area of origin for the spill. One particular tanker, rather than proceeding directly on a course from Spain to Argentina, stopped for two extended periods (each for approximately 14 hours) just within Brazil’s Exclusive Economic Zone (the EEZ area extends up to 200 nautical miles from shore). The tanker I identified with these unusual loitering events is The Amigo, a 133-meter vessel listed as an Asphalt/Bitumen tanker and flagged to the Marshall Islands. 

Figure 1. Tanker loitering events (yellow circles) detected by Global Fishing Watch analytical tools on the coast of northeast Brazil in July and August 2019 (filtered to events longer than 8 hours). Five loitering events near the area thought to be the likely origin of the spill are shown as larger circles and listed in the table below. The AIS track of tanker The Amigo is shown in red. The EEZ boundary marking Brazil’s waters is in green.

We checked for satellite imagery in the area where the vessel was drifting (July 24 – 26) and unfortunately didn’t turn anything up. So any possible association between this tanker and the oil spill is purely speculative. However, some of the circumstances of the vessel’s operation fit with theories on the source of the spill, so we think its activities should be scrutinized further.

The Amigo is an unusual tanker in that it is outfitted to maintain its cargo at high temperature to keep it from solidifying. When the tanker passed through Brazilian waters off Brazil’s northeast coast, it was en route from Cadiz, Spain to a port near Buenos Aires, Argentina. The loitering events occurred between July 24 and July 26 before the vessel proceeded to Argentina. Port records show that on August 10 the vessel delivered 14,000 tons of bitumen (or at least it was scheduled to offload that quantity of product). AIS confirms that the tanker reached dock in Campana, Argentina on August 10. 

The tanker was coming from Cadiz, Spain though we don’t know if the asphalt was actually from Spain or what quantity was loaded at the port facility in Cadiz. Earlier this year the vessel visited Venezuelan ports and imported Venezuelan asphalt to the US. This article from March mentions The Amigo in the context of US sanctions against Venezuela that were coming into force. Could The Amigo have been carrying a cargo of asphalt that originated in Venezuela?

Figure 2. Movements of The Amigo since January 2019. The tanker’s current location in Turkey is shown.

The terms asphalt and bitumen appear to be used interchangeably to describe a semi-solid form of petroleum. High heat tankers like The Amigo must maintain their cargo at an elevated temperature so that it does not solidify, and can be pumped out of the vessel. Problems with heating might result in product remaining in one of the ship’s tanks and needing to be flushed out. Even under normal operations, heavy oil residue can build up in the cargo tanks and needs to be washed out or removed to free up usable space. International law requires that this be done in port where the oily sludge can be treated, but many ports lack the necessary treatment facilities. If somehow asphalt did end up being discharged directly into the ocean it would be expected to drift below the surface in warm equatorial waters. This might not generate a large surface oil slick that could be seen on satellite images, possibly explaining our frustration here at SkyTruth. 

As mentioned, there are some legitimate reasons for a tanker to be drifting out at sea. But we think it is fair to pose some further questions about this vessel given the severity of the spill in Brazil. What prompted the vessel to halt its normal transit off Brazil? What was the origin of the asphalt carried by the vessel and what quantities were loaded and offloaded? Could the chemical properties of the oil found on Brazilian beaches match this cargo, or any oily residue remaining in The Amigo’s cargo tanks?

But it’s not just The Amigo that’s raising questions for us. We’ve detected loitering events by other tankers in recent months (as shown on the map above and in the table below). We’ve found evidence of likely bilge-dumping by a few vessels in the area. And we’ve noticed that more than a dozen tankers operating in this area turn their AIS off while at sea, apparently in violation of international maritime safety law.

Table 1. Table showing the five tanker loitering events detected near the likely source of origin of the Brazil oil spill, shown as large yellow circles on the map at top.

We hope to find out answers to some of these questions soon, and we will continue to investigate all available data that might help to identify the origin of this devastating oil spill. One problem is very clear: we don’t know everything we need to know about the tanker activity near Brazil, and in many other parts of the ocean. 

Update 19 Nov 2019 – Since posting this last week I’ve had a chance to get some input regarding the Bitumen tanker I identified as of particular interest, The Amigo. The 14,000 tons they were scheduled to offload in Argentina would represent close to the full carrying capacity of the vessel. With estimates of at least 2,000 tons of material recovered from the beaches it seems that the vessel could not be responsible if they delivered a full cargo. 

We remain puzzled by the properties of oil coming up on the beach. It has been clearly reported as floating below the surface which fits with the fact that no large slick has so far shown up on satellite imagery. It has been questioned whether any of the asphalt carried by a vessel like The Amigo would really remain in the water column and be able to float ashore, rather than sinking to the seafloor. So some sort of heavy crude seems to be the most likely source. 

We are continuing to investigate any possible leads on the source of the spill and will share any more information that comes up. 

Bilge Dumping off the Coast of Brazil

The cause of the massive oil spill plaguing Brazil’s beaches is still unknown, but monitoring reveals a potential new bilge dumping incident

We still haven’t found the cause of the massive oil spill that’s been plaguing Brazil’s beaches since early September.  

But SkyTruth’s continued surveillance of the coast of northeastern Brazil, in response to one of the country’s worst oil-related environmental disasters ever, has uncovered what appears to be another previously unreported bilge dumping incident off the coast of Joao Pessoa in the state of Paraiba. Located about 20 km offshore, a 25 km-long slick appears to originate from the Grajau, a Brazil-flagged liquefied petroleum gas (LPG) tanker. Slicks such as this are a hallmark of the intentional dumping of untreated, oily bilge wastes from vessels underway at sea, although there may be other explanations for this slick (for example, the ship was experiencing a serious mechanical problem). The slick (a long, dark streak) and vessel (a bright spot at the south end of the slick) are shown on this Sentinel-1 radar satellite image taken on the 19th of July. We identified the vessel using their public AIS tracking broadcasts, extracted from the ShipView vessel-tracking platform. The image was captured at 07:53 UTC; a careful look at the AIS broadcasts from Grajau just before and after the image was taken show that the vessel we can see on the radar image is very likely Grajau.

Recent discoveries of bilge dumping in the Atlantic Ocean along Brazil’s coast reveal that this is a persistent problem that — as in many places — lacks effective enforcement. None of the slicks we’ve seen appear big enough to be the source of the oil plaguing Brazil’s beaches. This potential bilge slick from Grajau is no exception: it’s a modest-sized slick compared with the dozens of bilge slicks we’ve seen from other places around the world that are occasionally more than 100 km long. And this slick, just 20 km offshore, probably would have dissipated or washed ashore several weeks before the thick globs of heavy oil began to appear on the beaches in early September.

Nevertheless, bilge dumping is a chronic source of oil pollution in the ocean that has been hidden for too long. Now that we can see it, and can identify the likely polluters, it’s time for governments to take action to bring this illegal practice to an end.

AIS ship-tracking broadcasts (red dots) from the Brazil-flagged LPG tanker Grajau, overlain on a Sentinel-1 radar satellite image showing an apparent bilge-dumping slick (dark streak) and the vessel that appears to be responsible (bright spot, indicated within the red circle). Based on the AIS data, we think this vessel is likely the Grajau. See inset map at upper right for detail. Image was collected at 07:53 on July 19.

The location of the boat, relative to Brazil’s coastline.

Bilge Dumping Caught in Indonesia – Again!

SkyTruth identified the bulk carrier Lumoso Aman as the likely polluter via AIS and satellite imagery.

On October 10, 2019, SkyTruth discovered yet another likely bilge dumping incident in Southeast Asian waters. At 10:25:26 UTC (Coordinated Universal Time), Sentinel-1 Imagery captured this oily pollution during routine monitoring of the Makassar Strait. Lingering off the southwest coast of Sulawesi, Indonesia, this oil slick measures approximately 33 kilometers long. The slick and the suspected responsible vessel (circled in red in Figure 1 below) appear roughly 100 kilometers west of the coast of Makassar, the capital of Sulawesi. Makassar is a port city with active commerce and tourism.

Figure 1: A vessel suspected of bilge dumping.

We identified the potential culprit through AIS (Automatic Identification System) broadcasts from the Lumoso Aman (Figure 2), a bulk cargo carrier operating under the flag of Indonesia. 

Figure 2: A picture of the Lumoso Aman, courtesy of Vessel Finder.

Bilge dumping is the disposal of waste water from a ship’s lower hull. Bilge water is supposed to be treated before it’s discharged, but sometimes vessel operators will bypass the pollution control equipment and flush oily, untreated bilge into the ocean – in direct violation of international marine pollution law. You can learn more about this ongoing source of ocean pollution, and how SkyTruth identifies perpetrators, in our recent post about bilge dumping in Southeast Asia.

Our motto at SkyTruth is “If you can see it, you can change it.” We tirelessly monitor the ocean with this vision in mind, to be watchdogs and defenders of our Earth’s waters. No matter how remote these areas of pollution appear to be, we can see them with satellite images. These seemingly remote bodies of water are connected to waters throughout the world. Just as air pollution migrates between contiguous countries or states, oil pollution can find its way to any coastline and harm coastal environments and communities. With continued monitoring, we hope that nations, communities, and enforcement agencies can hold ship operators accountable, making it clear that bilge pollution is an unacceptable threat to the world’s ocean ecosystems. 

Figure 3: SkyTruth intern Tatianna Evanisko tracks polluting vessels around the world from the SkyTruth offices in Shepherdstown WV. Photo credit: Johnna Armstrong.

What About the Oceans? Mapping Offshore Infrastructure

Mapping stationary structures in the ocean helps us track fishing vessels and monitor pollution more effectively.

We’re all accustomed to seeing maps of the terrestrial spaces we occupy. We expect to see cities, roads and more well labeled, whether in an atlas on our coffee table or Google Maps on our smartphone. SkyTruthers even expect to access information about where coal mines are located or where forests are experiencing regrowth. We can now see incredibly detailed satellite imagery of our planet. Try looking for your house in Google Earth. Can you see your car in the driveway?

In comparison, our oceans are much more mysterious places. Over seventy percent of our planet is ocean, yet vast areas are described with only a handful of labels: the Pacific Ocean, Coral Sea, Strait of Hormuz, or Chukchi Sea for example. And while we do have imagery of our oceans, its resolution decreases drastically the farther out from shore you look. It can be easy to forget that humans have a permanent and substantial footprint across the waters of our planet. At SkyTruth, we’re working to change that.

Former SkyTruth senior intern Brian Wong and I are working to create a dataset of offshore infrastructure to help SkyTruth and others more effectively monitor our oceans. If we know where oil platforms, aquaculture facilities, wind farms and more are located, we can keep an eye on them more easily. As technological improvements fuel the growth of the ocean economy, allowing industry to extract resources far out at sea, this dataset will become increasingly valuable. It can help researchers examine the effects of humanity’s expanding presence in marine spaces, and allow activists, the media, and other watchdogs to hold industry accountable for activities taking place beyond the horizon.

What We’re Doing

Brian is now an employee at the Marine Geospatial Ecology Lab (MGEL) at Duke University. But nearly two years ago, at a Global Fishing Watch research workshop in Oakland, he and I discussed the feasibility of creating an algorithm that could identify vessel locations using Synthetic Aperture Radar (SAR) imagery. It was something I’d been working on on-and-off for a few weeks, and the approach seemed fairly simple.

Image 1. SkyTruth and Global Fishing Watch team members meet for a brainstorming session at the Global Fishing Watch Research Workshop, September 2017. Photo credit: David Kroodsma, Global Fishing Watch.

Readers who have been following SkyTruth’s work are probably used to seeing SAR images from the European Space Agency’s Sentinel-1 satellites in our posts. They are our go-to tools for monitoring marine pollution events, thanks to SAR’s ability to pierce clouds and provide high contrast between slicks and sea water. SAR imagery provides data about the relative roughness of surfaces. With radar imagery, the satellite sends pulses to the earth’s surface. Flat surfaces, like calm water (or oil slicks), reflect less of this data back to the satellite sensor than vessels or structures do, and appear dark. Vessels and infrastructure appear bright in SAR imagery because they experience a double-bounce effect. This means that — because such structures are three-dimensional — they typically reflect back to the satellite more than once as the radar pulse bounces off multiple surfaces. If you’re interested in reading more about how to interpret SAR imagery this tutorial is an excellent starting point.

Image 2. The long, dark line bisecting this image is a likely bilge dump from a vessel captured by Sentinel-1 on July 2, 2019. The bright point at its end is the suspected source. Read more here.

Image 3. The bright area located in the center of this Sentinel-1 image is Neft Daşları, a massive collection of offshore oil platforms and related infrastructure in the Caspian Sea.

Given the high contrast between water and the bright areas that correspond to land, vessels, and structures (see the vessel at the end of the slick in Image 2 and Neft Daşları in Image 3), we thought that if we could mask out the land, picking out the bright spots should be relatively straightforward. But in order to determine which points were vessels, we first needed to identify the location of all the world’s stationary offshore infrastructure, since it is virtually impossible to differentiate structures from vessels when looking at a single SAR image. Our simple task was turning out to be not so simple.

While the United States has publicly available data detailing the locations of offshore oil platforms (see Image 4), this is not the case for other countries around the world. Even when data is available, it is often hosted across multiple webpages, hidden behind paywalls, or provided in formats which are not broadly accessible or useable. To our knowledge, no one has ever published a comprehensive, global dataset of offshore infrastructure that is publicly available (or affordable).

Image 4. Two versions of a single Sentinel-1 image collected over the Gulf of Mexico, in which both oil platforms and vessels are visible. On the left, an unlabelled version which illustrates how similar infrastructure and vessels appear. On the right, oil platforms have been identified using the BOEM Platform dataset.

As we began to explore the potential of SAR imagery for automated vessel and infrastructure detection, we quickly realized that methods existed to create the data we desired. The Constant False Alarm Rate algorithm has been used to detect vessels in SAR imagery since at least 1988, but thanks to Google Earth Engine we are able to scale up the analysis and run it across every Sentinel-1 scene collected to date (something which simply would not have been possible even 10 years ago). To apply the algorithm to our dataset, we, among other things, had to mask out the land, and then set the threshold level of brightness that indicated the presence of a structure or vessel. Both structures and vessels will have high levels of reflectance. So we then had to separate the stationary structures from vessels. We did this by compiling a composite of all images for the year 2017. Infrastructure remains stationary throughout the year, while vessels move. This allowed us to clearly identify the infrastructure.

Image 5. An early version of our workflow for processing radar imagery to identify vessel locations. While the project shifted to focus on infrastructure detection first, many of the processing steps remained.

Where We Are Now

Our next step in creating the infrastructure dataset was testing the approach in areas where infrastructure locations were known. We tested the algorithm’s ability to detect oil platforms in the Gulf of Mexico, where the US Bureau of Ocean Energy Management (BOEM) maintains a dataset. We also tested the algorithm’s ability to identify wind turbines. We used a wind farm boundary dataset provided by the United Kingdom Hydrographic Office to validate our dataset, as well as information about offshore wind farms in Chinese waters verified in media reports, with their latitude and longitude available on Wikipedia.

Image 6. Wind farms in the Irish Sea, west of Liverpool.

Our results in these test areas have been very promising, with an overall accuracy of 96.1%. The methodology and data have been published by the journal Remote Sensing of Environment. Moving beyond these areas, we are continuing to work with our colleagues at MGEL to develop a full global dataset. What started as a project to identify vessels for GFW has turned into an entirely different, yet complementary, project identifying offshore infrastructure around the world.

Image 7. This animated map shows the output of our offshore infrastructure detection algorithm results (red) compared to the publicly available BOEM Platform dataset (yellow).

In addition to helping our partners at Global Fishing Watch identify fishing vessels, mapping the world’s offshore infrastructure will help SkyTruth more effectively target our daily oil pollution monitoring work on areas throughout the ocean that are at high risk for pollution events from oil and gas drilling and shipping (such as bilge dumping). This is also the first step towards one of SkyTruth’s major multi-year goals: automating the detection of marine oil pollution, so we can create and publish a global map of offshore pollution events, updated on a routine basis.

Be sure to keep an eye out for more updates, as we will be publishing the full datasets once we complete the publication cycles.

More oil pollution in southeast Asia: suspected bilge dumping off Indonesia and The Philippines

[This analysis of oil pollution in the waters of southeast Asia was written as part of a collaborative effort between SkyTruth team members Lucy Meyer and Brendan Jarrell.]

Our routine monitoring of the world’s oceans has led to some extraordinary findings. For example, in previous updates, we’ve identified oil slicks in traffic-heavy locations like the Strait of Malacca. But as you’ll see in this post, bilge dumps occur elsewhere in southeast Asia. 

Those who follow our posts are probably familiar with how we identify vessels at sea. To new readers, let us explain what bilge dumping is and how we identify potentially responsible vessels. Bilge dumping is the disposal of waste water from a ship’s lower hull. Bilge water is supposed to be treated before it’s discharged, but sometimes vessel operators will bypass the pollution control equipment and flush oily, untreated bilge into the ocean – in direct violation of marine pollution law. We use images from satellites to monitor for illegal bilge dumping. In satellite imagery, oily bilge dumps usually form distinctive linear slicks. By matching the time of the imagery to broadcasts from a vessel tracking service called automatic identification system (AIS), we can determine the identity of vessels that appear to be causing the slicks. We used this process to identify the vessel associated with a long bilge slick in Figure 1 below.

 

Figure 1: A vessel shown passing through the Sunda Strait, identified as the Sungai Gerong, apparently trailing a long oily bilge slick.

 

This Sentinel-1 radar satellite image from July 2nd shows a slick about 177 kilometers long around the southwest tip of Banten Province, Island of Java, Indonesia (Figure 1). In the yellow box, you can see a vessel at the head of the slick. By investigating AIS broadcasts from exactEarth’s ShipView service, we identified an Indonesian oil products tanker named the Sungai Gerong as the likely vessel. The satellite scene, captured at 22:33 UTC (Coordinated Universal Time), shows a slick that closely aligns to the AIS broadcasts from the Sungai Gerong.

You’ll probably notice that the tail-end of the slick is a bit contorted and offset from the track of the Sungai Gerong. The slick’s appearance was likely influenced by ocean currents and local weather conditions between the time of the ship’s passing and when the image was taken. Global wind maps show that there were 10-15 knot winds blowing northwest up to six hours before the image was acquired. This data suggests that wind likely impacted the slick’s appearance. As a result, we believe that the Sungai Gerong is the likely source of this slick.

Using AIS, we tracked the Sungai Gerong as it traveled north through the Sunda Strait — the body of water between the Indonesian islands of Java and Sumatra — to the port of Jakarta. Similar to the Strait of Malacca, the Sunda is an important waterway that connects the Indian Ocean to the Java Sea. Though not as dense with marine traffic as the Malacca Strait, the Sunda is still subjected to pollution from vessels. 

We also recently identified two suspected bilge dumps in the Philippines (Figure 2). Occurring on July 6th in the South China Sea, a 238 kilometer long slick behind the vessel in this Sentinel-1 radar image looks like a bilge dump. The Philippine island of Palawan, a popular tourist destination for its beautiful natural landscape, appears on the right side of the map frame. Another smaller slick without a known source is visible to the left of the larger slick.

 

Figure 2: The Ulaya makes its way through the South China Sea. Palawan Island, a part of the Philippines, can be seen to the right.

 

Using AIS broadcasts from ShipView, we identified the Ulaya, a Thai oil tanker, as a possible source of the slick. The last AIS broadcast from the Ulaya (seen directly above the ship) was transmitted fifteen minutes before the image was captured. These AIS broadcasts give us reason to believe that the Ulaya could be responsible for this slick. Moreover, ShipView shows that the vessel was headed towards the Port of Belawan in the Strait of Malacca with a shipment of  Dangerous Goods. According to the International Maritime Organization, a United Nations agency that regulates global shipping, chemicals falling under this classification are “hazardous to marine environments.” Thus, a slick from this ship could be of greater concern than usual.

These examples show that bilge dumping continues to be a problem in the waters of southeast Asia. But with satellite imagery, anyone, anywhere can see what’s happening on the water and help to raise the alarm. We hope that our persistent and careful surveillance will inspire others to pressure policy makers, government regulators, and the shipping industry to take strong, coordinated action to stop bilge dumping.