State of the Planet

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Science Nabs Illegal Ivory Sellers

ivory trade, radiocarbon dating, elephant tusks
Carved elephant tusks seized in Canada were determined to be illegal using a radiocarbon test developed by Kevin Uno of Lamont-Doherty Earth Observatory. Photos: Todd Kish, Environment Canada

A Toronto-based company has been convicted of selling illegal ivory in the first case to use a technique for dating ivory developed by a scientist at the Lamont-Doherty Earth Observatory in collaboration with other colleagues.

Five Star Auctions and Appraisals, and its director, Mrs. Chun Al Jin, were charged after testing revealed two carved elephant tusks they were offering for sale had come from animals – possibly the same elephant — killed in late 1977 or early 1978. Under Canadian law, sellers must be able to prove ivory came from an animal taken from the wild before July 3, 1975, and that it was legally imported to Canada.

The case against the Toronto company is the first time that this dating technology has been used to obtain a conviction under wildlife law in Canada, and one of only a half dozen cases where radiocarbon dating has been successfully used worldwide, according to Environment Canada, a  government agency.

A 1989 international agreement bans commercial trade in ivory, with exceptions, including ivory harvested before 1976. Yet the amount of poaching has increased in recent years: A 2014 study found that poachers had killed an estimated 100,000 elephants in Africa between 2010 and 2012 and blamed the slaughter on increased demand for ivory in China and other Asian nations. Last week, China banned imports of ivory carvings for one year. Critics contend that move will have little effect on the illicit trade and continuing slaughter of elephants.

It has been difficult for law enforcement agencies to differentiate old from new ivory. That changed when scientists developed a new technique to radiocarbon date ivory and other organic materials, allowing for precise dating.

The method was described in a 2013 study in the Proceedings of the National Academy of Sciences (and in an Earth Institute story). Lead author Kevin Uno, a postdoctoral researcher at Lamont-Doherty, said he got a call soon after from Todd Kish, a field officer with Environment Canada, who had read about the new technique in a magazine article.

“We hadn’t been able to apply it to a real forensics case yet,” Uno said. Then, “Todd called me … and said we just seized some tusks from an auction house, and do you want to try this out? They were trying to figure out how to nail these guys, and the only way to do it was to date the tusks.”

But there was a snag: Under the Convention on International Trade in Endangered Species, it’s illegal to send the tusks from Canada to the United States, even for scientific purposes, without undergoing a lengthy permit process. Uno’s solution: Have a lab in Canada convert some of the collagen in the tusks into CO2 – basically by burning it. They then shipped the CO2 gas samples in small glass vials to the University of California-Irvine, which has one of a handful of labs in the world that can conduct radiocarbon testing. The results were definitive.

“You can’t really argue with this. The facts are right there,” Guillaume Labrecque, of the radiochronology laboratory at Quebec’s Laval University, who helped conduct the analysis, told the Canadian Broadcasting Company.

A chart of the "bomb curve" used in dating the two illegal elephant tusks.
A chart of the “bomb curve” used in dating the two illegal elephant tusks.

The Toronto company and its director pleaded guilty on Feb. 27 and were fined $9,375 each, and ordered to forfeit two elephant ivory tusks to authorities. The carved tusks reportedly measured 78 cm and weighing 1.7 kg each. According to a 2014 story in The Guardian newspaper, the price for a kilogram of raw ivory in China spiked to $2,100 per kilogram last year.

The dating of the tusks is based on a spike in radiocarbon (14C, a radioactive isotope of carbon) in the atmosphere, a result of above-ground thermonuclear weapons testing from 1952 through 1962. Radiocarbon testing before then can reveal an age, based on the rate of decay of the 14C, but it is less precise. Since the atomic tests, the abrupt rise and then fall in concentrations of 14C have allowed scientists to date an object more precisely along what’s called the “bomb curve.”

Further reading: A PBS review of laws regarding ivory trade.


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