MAC: Mines and Communities

New research throws STD into further doubt

Published by MAC on 2004-08-31

New research throws STD into further doubt

A new piece of research - published in the respected journal "Nature" - seems to bang another nail into the coffin of submarine tailings disposal (STD) in the Pacific Ocean. It reveals that unicell organisms are both essential to the generation of nitrogen, hence the nutritional health of the oceans, and may well exist at depths below 80-100 metres, the so-called "euphotic zone". To date mining companies supporting STD - notably Placer Dome, Newmont and Rio Tinto - have claimed this to be a "safe" depth for the dumping of mine wastes which they concede smother all life in their path (despite recent ongoing scandals with Newmont).

The STD afficionados appear to have got it badly wrong. But even if they hadn't - as the lead biologist for this study points out in implicit support for the "precautionary principle" -"We're still at a very early stage of understanding how things work in these enormous pieces of ocean".

Unicell Organisms Play Big Role in Oceans' Nitrogen

Environmental News Service (ENS)

August 31, 2004

Washington DC - Large, nutrient poor expanses of the open ocean are getting a substantial nitrogen influx from an abundant group of unicellular organisms, researchers say.

These tiny organisms, some seven microns in diameter, "fix," or chemically alter, nitrogen into a form usable for biological productivity.

First identified about five years ago, these organisms are fixing nitrogen at rates up to three times higher than previously reported for the Pacific Ocean, according to research published in last week in the scientific journal "Nature."

"To our surprise, these unicellular nitrogen fixers are broadly distributed spatially and vertically distributed at least down to 100 meters, and they are fixing nitrogen at quite high rates," said Joe Montoya, a biologist at the Georgia Institute of Technology and lead author of the paper.

Montoya says the rates measured by the research team exceeds the rate of nitrogen fixation measured for the organism traditionally believed to be the dominant "marine nitrogen fixer" in the Pacific Ocean.

"These unicells are the largest single source of nitrogen entering the water in broad areas of the ocean," he said.

This level of nitrogen fixation in the Pacific Ocean alone accounts for about 10 percent of the total global oceanic new production of biomass, according to the researchers' preliminary calculations.

The ongoing study is increasing scientists' understanding of the fertility of the ocean, according the research team.

"This group of tiny, photosynthetic organisms, whose contribution to the fertility of the ocean is significant, appears to play a critical role in driving the movement of elements through the ocean both in the upper layer of the water and from the atmosphere into the ocean," Montoya said.

The nitrogen fixation rates reported in the study are conservative figures, Montoya said, and may underestimate the true rate of nitrogen fixation by a factor of two.

The research team will continue to survey the Pacific Ocean, as well as the north Atlantic and the south Pacific Oceans in two research cruises in 2006 and 2007.

In the south Pacific, Montoya expects to find high rates of nitrogen fixation by unicells, he said.

Measurements already taken in the marginal waters of the South Pacific - off the coast of northern Australia - yielded the highest recorded rates of nitrogen fixation by unicells to date.

There are still numerous regions of nutrient poor oceans - typically off the continental shelves from the equator north and south to about 40 degrees latitude - in which little or nothing is known about unicellular nitrogen fixing organisms, Montoya added.

"We are still at a very early stage in understanding ocean science and how things work in these enormous pieces of the ocean," he said.

Home | About Us | Companies | Countries | Minerals | Contact Us
© Mines and Communities 2013. Web site by Zippy Info