Posted in | News | Pollution

AAAS Confirms Recurring Oil Slick in the Caspian Sea

Analysis by the nonprofit American Association for the Advancement of Science (AAAS) confirms the release of oil into the waters of the Caspian Sea off Turkmenistan, and demonstrates an innovative new use of publicly available imaging technology.

AAAS analysis of WorldView-2 imagery from 27 March 2011 confirmed an unusual feature (indicated by the red arrow) believed to be a recurring oil slick in the Caspian Sea. The feature, nicknamed “the squiggle,” originates at 39.548 degrees North, 52.616 degrees East and is flanked by drilling rigs (inset). Some of the rigs appear to be derelict and in a state of disrepair. Credit: © 2013 DigitalGlobe

The work describes "hundreds of instances in which petroleum discharge has taken place near drilling platforms in the Caspian Sea, and another leak adjacent to oil fields on the shores of the Turkmenbashi Gulf," said Susan Wolfinbarger, director of the AAAS Geospatial Technologies and Human Rights Program. "Our analysis appears to corroborate on-the-ground reports of environmental pollution in the waters adjacent to the port of Turkmenbashi, Turkmenistan."

Such reports followed the May 2005 opening of the Baku-Tbilisi-Ceyhan pipeline, which transports oil from Baku, Azerbaijan, to Ceyhan, Turkey. The pipeline has resulted in increased oil production, Wolfinbarger explained. Groups such as Crude Accountability and the Turkmen Initiative for Human Rights have expressed concerns about oil pollution in and around Turkmenbashi Bay.

At Crude Accountability, a human rights and environmental organization, Executive Director Kate Watters said: "There are significant concerns about the impacts of human activities on the Caspian Sea. For the first time, the AAAS analysis demonstrates that there really is oil coming from the Turkmen part of the sea. The sea is a closed body of water. There are serious threats to Caspian seals and to sturgeon, and since much of the world's caviar comes from that area, the situation poses a significant economic risk. We also are questioning what impacts oil pollution in the region may have on human health."

Some key questions about Turkmenistan oil pollution remain unanswered by the analysis, according to the AAAS team, which included Program Associate Jonathan Drake and Senior Project Coordinator Eric Ashcroft. For example, the AAAS report describes one recurring sea plume that might be the result of a natural underwater mud volcano. Other instances of possible oil contamination in Turkmenbashi harbor may have been caused by leaks that began in Soimonov Bay. Further study is needed to resolve these and other questions, Wolfinbarger said.

A New Approach to Oil-Slick Detection

But the research has identified multiple oil slicks, and it also may help to improve oil-slick detection methods.

To assess oil slicks, Drake explained, researchers traditionally have used a technology called synthetic aperture radar, or SAR. This approach produces an image by measuring the intensity and frequency of multiple radar pulses as they echo, or bounce off a target. Methods based on SAR pinpoint areas of unusually still water where surface turbulence has been calmed by a thick layer of viscous oil. While SAR helps scientists accurately detect oil slicks, even through clouds or at night, the technology is expensive, and radar images are not collected continuously.

The team needed another tool to study oil pollution trends in Turkmenistan from 2000 to 2012. They turned to a NASA technology known as Moderate-Resolution Imaging Spectroradiometer, or MODIS. This instrument, which is carried aboard NASA's Terra and Aqua satellites, captures images of the entire Earth every one to two days, based on measurements of the radiant energy reflecting off different objects. The technology cannot detect oil slicks through clouds, and images are affected by the angle of the sun, but MODIS is less costly than radar-based images and it offers greater coverage, potentially making it a more practical choice for longer-term monitoring projects.

Wolfinbarger and colleagues used MODIS data, including 6,809 images from the Terra satellite and 4,852 images from the Aqua satellite, to look at a portion of the Caspian Sea and Turkmenbashi Bay. A list of possible oil slicks was then developed, with help from NASA's SeaWIFS Data Analysis System. Selected SAR images were also acquired, along with some high-resolution optical images, to help confirm the MODIS observations. The European Space Agency's NEST ESA SAR Toolbox was used to filter out noise and classify oil slicks revealed by SAR.

Limited MODIS images were available for the first three years of the study period. Between 2003 and 2012, however, the AAAS team identified between 43 and 64 possible oil slicks every year in Turkmenbashi Bay.

More than half of all likely oil slicks were part of an irregular serpentine feature, nicknamed "the squiggle," located about 55 kilometers west-northwest of the Cheleken Peninsula. By overlaying multiple apparent oil slick images, Wolfinbarger's team was able to pinpoint a source location, which is surrounded by drilling platforms. Two of those rigs, in particular, appeared to be derelict and "in a state of considerable disrepair," according to the AAAS report. The surrounding slick "exhibits a silvery sheen" and was estimated to range from 0.04 microns to 5.0 microns thick, taking on rainbow colors where it is most dense, the report states.

A particular slick on 27 March 2011 was estimated to contain as much as 3,200 liters of oil, and more than 400 similar incidents were documented between February 2000 and December 2012.

In addition to the "squiggle" that is believed to be a recurring oil slick, the AAAS team identified another unusual feature they called the "plume." Clearly visible only in high-resolution optical images, the plume appeared to emit both steam and water-borne sediment, probably originating from a submarine mud volcano.

The Caspian Sea region includes a number of delicate ecosystems now being threatened by land-use changes and development including oil, Watters of Crude Accountability said. Oil is currently transported from Turkmenistan to the BTC pipeline by tanker, but a Trans-Caspian pipeline has been proposed, she added

"Environmental threats to human health, and the failure of authorities to respond to such cases, have increasingly been considered a potential human rights violation," said Mark Frankel, director of the AAAS Scientific Responsibility, Human Rights and the Law Program. For example, he noted, the United Nations Office of the High Commissioner for Human Rights has concluded that "a safe, clean, healthy and sustainable environment is integral to the full enjoyment of a wide range of human rights."

Research Also Confirms Residential Demolition

In related research, AAAS assessed the reported demolition of two towns located near Turkmenbashi on the Caspian Sea: Avaza and Tarta. The Turkmen Initiative for Human Rights has said that residents of these towns were forcibly evicted from their homes without compensation to make way for a modern luxury resort—part of a government plan to make the region an international tourist destination.

Analysis of four high-resolution images of Avaza and Tarta, captured before and after construction of the resort (between 2002 and 2010), revealed widespread demolition of structures. In Avaza, 1,993 structures were seen in 2002, yet only 46 remained in 2010, and most of those were part of the Presidential or hotel complexes. In Tarta, 512 structures were seen in 2009, compared with 186 in 2010.


Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback