CAMBRIDGE, Mass., July 8 (UPI) -- "Legacy" pollution means ocean levels of mercury will be greater in the future unless stringent emissions reductions are put in place, U.S. researchers say.
Environmental researchers at Harvard University report so much mercury persists from pollution going back thousands of years it will continue to persist in the world's waters and accumulate in fish for decades to centuries.
Significant reductions in mercury emissions will be required just to stabilize current levels of the toxic element in the environment, the researchers said in a Harvard release Monday.
"It's easier said than done, but we're advocating for aggressive reductions, and sooner rather than later," lead study author Helen Amos, a doctoral candidate in Earth and Planetary Sciences, said.
The researchers, collecting historical data on mercury emissions as far back as 2000 B.C., said computer models show most of the mercury emitted to the environment ends up in the oceans within a few decades and remains there for centuries to millennia.
Humans have been releasing mercury into the environment for thousands of years, they said; for example, ancient Greeks and Chinese used mercury as a pigment, and in the 16th century Spanish colonists in Central and South America were using it to extract silver.
"Ideally, mercury released by human activities would quickly be sequestered in the environment, but instead what we see is a huge quantity of it bouncing from one reservoir to the next," from atmosphere to soil to oceans, researcher Elsie M. Sunderland said.
"This means it continues cycling throughout the environment and persists for much longer timescales than most people realize, which has implications for long-term biological exposures."