Possible Bilge Dumping, Offshore Brazil

We’ve been looking at satellite imagery of offshore Brazil regularly since Chevron’s November 2011 blowout and spill in the Campos Basin.  Yesterday Teri noticed what appears to be a 40-mile-long, thin slick about 50 miles offshore in the southern part of the Campos oil field, playing hide-and-seek between the clouds and cloud shadows, on a MODIS/Terra satellite image:

Detail from MODIS/Terra satellite image taken on February 25, 2014, showing apparent bilge-dumping slick from a vessel operating in or passing through the Campos Basin oil field, offshore Brazil. Oil platforms and FPSOs shown as purple dots. Image courtesy of NASA/MODIS Rapid Response Team. 

Given the location, one might suspect this is a leak from one of the many oil platforms or FPSOs in this area, shown as purple dots in the image above.  Petrobras platform Namorado-2 is located close to the north end of this slick. But we think, given it’s length and consistent width, this is more likely a bilge-dumping slick or leak from a passing vessel than a leak from a platform.

Is bilge dumping legal in Brazilian waters?  And who is the culprit? There is plenty of coastal shipping activity in this area, including cargo ships that we’ve caught dumping bilge elsewhere. There is also a lot of tanker traffic here, hauling oil from the FPSOs offshore to storage facilities and refineries onshore, occasionally causing spills here in Brazilian waters.

If we had to place a bet, we would guess this is bilge dumping from a shuttle tanker serving the Campos Basin oil facilities. Teri is running through the AIS data now to see if she can identify the source of this slick.

Suspected Bilge Dumping off Corsica

We got a tip early this morning from a friend in France that an oil spill had been reported in the Mediterranean Sea off the northwest coast of Corsica.  Today’s MODIS images showed nothing of interest.  But we did find a brand-new Landsat-8 satellite image that was taken yesterday (September 2), and it shows two parallel slicks that appear to be bilge-dumping incidents. We’ve really boosted the contrast in the images below, so you can more clearly see the slicks.

The largest slick is at least 90 km (56 miles) long; at the north end it disappears into clouds and haze. The smaller slick to its west is about 41km (25 miles) long.  Both are very sinuous, suggesting they are at least a day or so old and have been pushed around by the wind and current.

Bilge-dumping is a definite no-no in the Mediterranean.  Hopefully the CleanSeaNet program is on top of this and will track down the offenders.  Careful study of AIS data might identify the likely culprits.

Detail from a Landsat-8 satellite image taken on September 2, 2013 (inset) showing likely bilge-dumping slicks off the northwest coast of Corsica.
Detail from above. Bright spot at south end of slick to the west is a large vessel moving to the north; probably not associated with this pollution incident.

Bilge Dumping? Busted Using Satellite Images and AIS Data

Remember that 92-mile-long bilge dump off Congo and Angola that caught our attention back in April?

SkyTruth Angola no markups
Envisat ASAR satellite radar image showing bilge-dump slick (long dark streak) off Angola on April 6, 2012. Image courtesy European Space Agency.

The bright spot at the left end of the slick is likely the vessel that caused it.  But the ASAR imagery left an important question unanswered: Who was responsible for this pollution?

With the generous help of our new partners, SpaceQuest, new information has surfaced that helps put a name on that bright spot:  the Dona Liberta, a refrigerated cargo ship owned by NaviFruit LTD. This vessel has made unfortunate news in the past.  On July 4, 2011, the ship’s captain dumped two Tanzanian stowaways in Liberia’s territorial waters, strapped to empty barrels. One of the stowaways died while receiving medical treatment after washing up on shore. In November 2011 the vessel was laid up in the River Fal in England, stranding two Romanian watchmen on board in unsanitary conditions who were rescued by a charitable organization. And in February 2012, the Dona Liberta spilled 70-90 gallons of oil in the River Fal, prompting a cleanup response from local authorities.

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The Dona Liberta, courtesy of Shipspotting.com © Juan B

So how did we figure this out?

Read all about it after the jump….

In the ASAR satellite radar image, we can determine the exact time and date of the event, the coordinates of the start and end point of the slick, the length of the slick, and the heading of the vessel:

SkyTruth Angola w Markup

 

SpaceQuest builds satellites that intercept Automatic Identification System (AIS) data broadcast by vessels at sea.  AIS data typically include a vessel’s identification, position, heading and speed. Vessels broadcast this information, and collect it from others, to help avoid collisions with other vessels.  Insurance companies require the use of AIS by most commercial, insured vessels that are underway.  SpaceQuest gave us AIS data for the region spanning a 24-hour period, enabling us to identify vessels that were operating in the area around the same time the radar image was taken. After doing some simple math, we had enough information to pinpoint the likely culprit.

dona_liberta4

 

The observed location of the vessel on the radar image is labeled. Red dots show the positions of vessels recorded by AIS data. Red dot at upper left marks the position of the Dona Liberta, 39 miles northwest of observed location of vessel.

AIS data for a vessel 39 miles northwest from the observed location of the ship gave a heading of 293.8° and a speed of 15 knots (17.3 mph), and identified it as the Dona Liberta. This AIS information was broadcast 2.25 hours after the radar image was taken. If the ship traveled for 2.25 hours at 17.3 mph, then the ship traveled 38.925 miles, very close to the measured distance between the observed location and the AIS position.

dona_liberta5

The heading of the ship was reported by AIS to be 293.8°, only 1.1° off from the measured heading of 294.9°.  I also calculated where the vessel should be, had it been traveling for 2.25 hours at the AIS-recorded heading from the location observed on the satellite imagery. The ship would have ended up only 0.79 miles from the AIS-recorded location. No other vessels appear anywhere near this location on either the radar image, or the AIS data, making the Dona Liberta a likely culprit for this bilge dumping.

dona_liberta6
Difference between AIS-recorded position of vessel and calculated position based on observed location and AIS-recorded heading and speed.

 

But a ‘good idea’ of who dumped this material really isn’t good enough. After checking back with SpaceQuest on our findings, they supplemented our data with a compilation of the Dona Liberta’s AIS data for the previous 24 hours. From that, we were able to determine more about the trajectory of this vessel:

Dona_Liberta_Track
Possible route of the Dona Liberta (green line) drawn by simply connecting the red dots (AIS recorded positions). The slick may have drifted southward under the influence of currents and surface wind.

The observed location of the vessel in the radar satellite image was bracketed by two AIS data points, so there was more information available to cross reference with our current suspect. By comparing the time of each AIS point, with the time of the ASAR image, as well as the distance between them, the rate of travel was confirmed:

dona_liberta8
The green line connects two AIS data points that bracket the observed location of the vessel. Yellow and pink lines are distances calculated from the AIS-reported speed at both points, resulting in predicted positions for the vessel that are nearly identical to the actual observed location on the radar image.

The distance between the eastern AIS position to the observed location (yellow line) is 16.9 miles, and the vessel’s speed according to AIS was 15.1knots (17.377 mph), giving a travel time of 58.4 minutes. The actual time difference between the radar image and the AIS broadcast is 54 minutes. On the other side, the distance between the western AIS point and the observed location (pink line) is 9.66 miles, with the vessel speed at 15.2 knots (17.49 mph), implying a travel time of  33.1 minutes compared with the actual time difference of 36 minutes. These measurements are not exact but are very close, with no other vessels in the vicinity that could be confused with the Dona Liberta.

 

Bilge dumping is illegal in the United States, Europe and Canada.  We don’t know what the law is governing bilge dumping off Angola. But we’re encouraged that we now have the tools to not only spot this activity, but to identify the likely offenders. And if they don’t care, maybe their insurers and clients will.

Extreme Bilge Dumping, Angola

UPDATE: We figured out who the culprit was! Read all about how we identified the guilty party- FROM SPACE:


Original Story: We’ve been collecting quite a number of images showing the ongoing problem of bilge dumping across the globe and here is one that really catches the eye. This image, courtesy of the European Space Agency, was captured off the coast of Angola on April 6. It shows what appears to be an oily bilge dump approximately 92 miles long. The bottom image shows that you can clearly see the vessel that is probably responsible, circled in red:

 Radar satellite image showing a 92 mile long bilge-dump slick, taken on April 6, 2012. Envisat ASAR image courtesy European Space Agency.

 
You can be sure that we look at images such as this everyday and when we see ’em, you’ll see ’em. Eyes everywhere.

Bilge Dumping off Vietnam – February 22, 2012

We’ve posted about bilge dumping before – the practice of flushing the oily slop out of your vessel, straight into the ocean.  It’s illegal in a lot of places, but it is very hard to enforce.  SkyTruth’s daily offshore monitoring program just caught this fine (awful?) example of bilge dumping off the coast of Vietnam, in a major north-south shipping lane about 115 miles offshore:

Envisat ASAR satellite radar image off Vietnam, February 22, 2012. Image courtesy European Space Agency.

Zooming in on those black streaks, and turning the image west-up, here’s a closer look at this mess:

Envisat ASAR image courtesy European Space Agency.

More images and analysis after the jump….


The slick at bottom left is 30 miles long. Assuming the oil is only one micron thick – that’s probably way too conservative – we calculate this slick holds at least 16,600 gallons of oily gunk:

Envisat ASAR image courtesy European Space Agency.

Busted!  Sort of.  Following the visible stern wake, we come to a vessel 30 miles away, the likely perpetrator for this particular slick:

Envisat ASAR image courtesy European Space Agency.

If anybody has access to AIS (automated identification system) data, they can probably ID this vessel for us.  It’s location is  12.820307° N / 111.724137° E, heading 33°, time 02:37:19 UTC on February 22, 2012.  Go get ’em!