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.

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.

Monitoring the tailings dam failure of the Córrego do Feijão mine

On Friday, January 25th, the tailings dam to the Córrego do Feijão mine burst near Brumadinho, State of Minas Gerais, Brazil (the moment of failure was captured on video). Operated by Brazilian mining company Vale S.A., this incident recalls the collapse of Vale’s Samarco Mine in 2015 which unleashed 62 million cubic meters of toxic sludge downstream. As of Monday, the death toll reached 120, however, the full extent of damage is unknown. To monitor the impact, here is a Sentinel-2 scene of Córrego do Feijão from eighteen days before and seven days after the dam’s failure. As of February 2nd, approximately 2.85 km2 of sludge surrounds the region.

Sentinel 2 scene showing the extent of flooding as a result of the tailings dam failure. As a result of the failure, 3 billion gallons of mining waste were spilled.

This slider, below, shows the area near the town of Brumadinho before and after the dam failure with the inundation highlighted in yellow, it can be accessed here.

The Search for Sanchi

On January 6th, a tanker named the Sanchi collided with a cargo ship called the CF Crystal in the East China Sea causing a fire which killed nearly all of the crew and eventually sank the Sanchi. While the CF Crystal (which survived the collision) was only carrying grain, the Sanchi was carrying natural-gas condensate. This ultra-light oil is highly flammable which no doubt contributed to the blaze that prevented any rescue of the crew. Though there was originally hope it would evaporate quickly, there have been reports of it approaching the Japanese coastline. More persistent heavy bunker oil from the ship’s fuel tanks might also be leaking, compounding the problem.

Usually, we use radar imagery collected by the European Space Agency’s Sentinel 1 satellite to track and monitor oil slicks, but, in this case, the area is not completely covered by Sentinel 1, and what imagery we have seen has been washed out by strong winds that make it difficult to see slicks. We’ve been relying on multispectral imagery from Sentinel 2, but heavy cloud cover in the area has made it difficult to locate the slick and monitor the cleanup and salvage operations.

These Sentinel 2 images do not show the slick as clearly as radar images would. Because we are working in the visible spectrum, we can only see a faint difference between the ocean and the lighter-than-usual slick. We’ve done our best to boost the contrast to highlight the slick, so the color of the water might seem a little brighter than usual.

Sentinel 2 image taken on January 18, showing vessels and slick around site of Sanchi wreck. We inferred the location of Sanchi based on the movements of response vessels, reconstructed from their AIS tracking broadcasts.

We can see two vessels which appear to be either spraying chemicals to disperse the slick or deploying oil-skimming gear, from booms extending from either side, as shown in this zoomed image:

Closeup view of the previous image, showing cleanup vessel in greater detail.

This Planet image, also taken on January 18, showing part of a larger area of slick east of the Sanchi.

Thanks to Planet and their fleet of Dove satellites, we can see that the slick extends further to the east. We are also able to see the vessels in more detail:

This collection of close-up shows views of oil spill response vessels in the area from the previous image.

We have been following the ships in the area via their Automatic Identification System (AIS) broadcasts, and have seen a variety of Chinese and Japanese vessels come and go, including the Koyo Maru and Koshiki, Japanese patrol boats; the Dong Lei 6, a cleanup tanker; the Shen Qian Hao, a Chinese diving vessel; the Hai Xun 01, a Chinese Patrol Boat; and the Dong Hai Jiu 101, a Chinese Search and Rescue boat.  Based on the movements of these vessels, we’ve inferred the location where the Sanchi likely sank and is the source of this ongoing spill.

We are doing our best to monitor this area as the clean-up continues.

Port Aransas

Oil Spill Off Port Aransas, Texas

Around 4:30 am on October 20, a barge filled with nearly 5-½ million gallons of crude oil exploded off the coast of Port Aransas, Texas. Two crewmen lost their lives, and although the cargo holds reportedly were not breached, the crippled vessel began leaking oil into the Gulf. The U.S. Coast Guard reported a spill roughly two miles long and a quarter mile wide, and response crews were seen setting up oil booms by late afternoon. By the end of the weekend, more than 6,000 feet of containment booms had been placed to protect essential habitat areas along Mustang and North Padre islands.

Port Aransas Spill

Satellite imagery from Planet shows the spill at a resolution of three meters, just two days after the explosion. The spill spread out off Port Aransas and started drifting slowly south toward Mustang Island State Park and Padre Island National Seashore – critical wintering habitat for migratory birds including the red knot and the piping plover, both listed as threatened under the U.S. Endangered Species Act.

The Coast Guard issued a news release late on October 25 indicating the barge had been moved to shore. Beach cleanup teams continued to work on Mustang and North Padre islands, where more than 70 cubic yards of “oily solids” have been removed. Some shorebirds have been seen with oil on them, but wildlife teams have had difficulty catching and cleaning any of them. If oiled wildlife is rescued, they’re likely to go to the University of Texas Marine Science Institute’s Amos Rehabilitation Keep (ARK) for treatment.