Erik Rifkin (left) and an unidentified Mote Marine Laboratory… (Courtesy of National Aquarium,…)
Scientists from the National Aquarium and the Johns Hopkins University say they've found low but potentially harmful levels of toxic oil contaminants in the Gulf of Mexico months after the Deepwater Horizon well blowout was capped.
Erik Rifkin, interim executive director of the aquarium's conservation center, and Yongseok Hong, a post-doctoral fellow at Hopkins, say that using devices that mimic the way fish absorb contaminants in their environment, they've detected oil-related chemical compounds on the Louisiana coast that traditional water sampling methods mostly missed.
"Whether the values are problematic, we don't know," Rifkin said in an interview. "But there's no reason — except for money or interest, maybe — that people can't go out and do this all over the Gulf."
Rifkin and Hong are to present preliminary findings at a two-day symposium on the Gulf spill that starts Thursday at the National Aquarium. They're pressing for a wider search for low-level contamination left behind by the blowout with passive sampling devices such as the ones they used.
The federal government is taking a wide-ranging look at what harm the spill caused. The Natural Resources Damage Assessment, as it's known, will be the basis for a federal lawsuit seeking compensation from BP and other parties. Even before the case is settled, BP has agreed to pay $1 billion to jump-start restoration work.
Concerned that the government assessment may be missing the full extent of the spill's contamination, the Baltimore team deployed "semipermeable membrane devices" in the water, which can pick up traces that are undetectable otherwise because they are in extremely low concentrations. Commonly called "virtual fish," the gadgets hold a lipid or fat that will collect certain chemicals from the water, much as they "bioaccumulate" in the fatty tissue of fish.
The aquarium began monitoring water and beaches in Sarasota, Fla., in summer 2010 as oil continued to leak from the ruptured offshore well. Though 5 million barrels escaped into the Gulf, it never reached Sarasota's beaches. The researchers expanded their study to cover marshes and inshore waters in Alabama, Mississippi and Louisiana. The sampling work was done in collaboration with Mote Marine Laboratory in Sarasota.
Rifkin said that only a small percentage of the "grab" samples taken last year by the Environmental Protection Agency of Gulf water and sediments detected any polycyclic aromatic hydrocarbons, or PAHs. They are a toxic suite of chemicals commonly found in crude oil, some carcinogenic while others are "endocrine disruptors" capable of affecting reproduction and development of people, fish and other wildlife.
The Baltimore team is still analyzing the samples. But PAHs turned up in Barataria Bay, La., where Hong said oil was still visible in the marshes and even in the water.
Lisa DiPinto, who is overseeing the spill damage assessment for the National Oceanic and Atmospheric Administration, said she couldn't discuss the findings because of the pending legal case, but she noted that much of the data collected is public.
In some cases, she said, federal scientists have used passive samplers similar to the ones deployed by the Baltimore researchers. But in attempting to measure the effects of contaminants on living organisms, she said, it's sometimes better to study them directly, as the NOAA has with its "Mussel Watch" program monitoring the health of bivalve beds in coastal waters.
Donald F. Boesch, president of the University of Maryland Center for Environmental Science and a member of a presidential commission appointed to study the causes of the Gulf spill, said there are technical and legal challenges to looking for low-level contaminants using the Baltimore team's techniques.
Since it's been more than a year since the spill stopped, he said in an email, "the time for worrying about sublethal concentrations in the water is long over, except perhaps where there is some nearby oil residue, such [as] in oiled marshes." Even if low-level concentrations are picked up in the water, he added, that doesn't prove that fish and wildlife were exposed or that it affected them.
Edward J. Bouwer, a Hopkins environmental engineering professor involved in the research, acknowledged more studies would be needed to prove exposure and harm. But he said it's still important to look for low-level contamination when traditional water samples don't detect any.
"BP is going to say there's no problem here, when we feel like there still could be residual oil," said Bouwer. "We just want to do a better job of being able to assess the damages and take a long-term perspective. … We don't want them to walk away from this."