Hype about Mercury in the oceans

“A new paper by a group that includes researchers from the Woods Hole Oceanographic Institution (WHOI), Wright State University, Observatoire Midi-Pyréneés in France, and the Royal Netherlands Institute for Sea Research appears in this week’s edition of the journal Nature and provides the first direct calculation of mercury in the global ocean from pollution based on data obtained from 12 sampling cruises over the past 8 years. The work, which was funded by the U.S. National Science Foundation and the European Research Council and led by WHOI marine chemist Carl Lamborg, also provides a look at the global distribution of mercury in the marine environment,” says the press release.

 What made headlines in the press is this: “Analysis of their results showed rough agreement with the models used previously—that the ocean contains about 60,000 to 80,000 tons of pollution mercury. In addition, they found that ocean waters shallower than about 100 m (300 feet) have tripled in mercury concentration since the Industrial Revolution…..” “Tripled” is what the press picked up, but most sources did not print the rest of the sentence: …” and that the ocean as a whole has shown an increase of roughly 10 percent over pre-industrial mercury levels.”

But “tripled.” Wow. How much is that? According to the researchers, the tripling amounts to a concentration of 0.6 parts per trillion in the upper ocean (that means it changed from 0.0000000000002 to 0.0000000000006, less than one molecule of mercury per liter of water). Are instruments so refined that they can even measure such a small amount? And, how do they know how much mercury was in the oceans in pre -industrial times?

As it turns out, the researchers could not actually measure mercury present in pre-industrial times. Rather, “The group started by looking at data sets that offer detail about oceanic levels of phosphate, a substance that is both better studied than mercury and that behaves in much the same way in the ocean… By determining the ratio of phosphate to mercury …the group was able to estimate mercury in the ocean that originated from natural sources such as the breakdown, or weathering, of rocks on land.” In other words they made a very big assumption.

The researchers also said that current mercury concentration is lower than that reported in several previous papers.

Let’s look at the bigger picture. The following is from a fact sheet published by the Science and Public Policy Institute:

Mercury (Hg) is an element that has existed (and will continue to exist) naturally since the earth was formed 4.5 billion years ago. The oceans alone contain millions of tons of mercury. [So called “pollution mercury” even at 80,000 tons is small compared to the naturally-occurring millions of tons.]

There are two major forms of mercury emitted during fossil fuel combustion:

1. Oxidized, which is water soluble and can be washed out of the air into rivers, lakes, and streams.

2. Elemental, which is not water soluble and moves around in a global mercury cycle.

A small fraction (about one one-thousandth) of the oxidized mercury that ends up in waterways may be changed into an organic form called methylmercury (MeHg) which is the kind of mercury with which EPA is concerned. This type of mercury can be eaten by tiny organisms that are then eaten by small fish, resulting in possible bioaccumulation in larger fish eaten by humans.

Methylmercury is not emitted directly from fossil-fuel-fired power plants. It is produced and

accumulated within the biosphere by a myriad of mercury transformation processes that do not depend upon the amount of inorganic mercury emitted from man-made sources. The natural cyclical production and destruction is controlled by environmental factors and ecosystem processes that are largely beyond human control or intervention.

A new estimate by scientists from the National Center for Atmospheric Research shows that mercury emissions from forest fires in the lower 48 U.S. states and Alaska amount to about 44 tons per year. This is of similar magnitude to the total mercury emissions from U.S. power plants. When estimates of all natural sources are considered, including geothermal events under oceans and lakes, US power plants may account for as little as 0.002% of the entire annual world mercury emissions budget.

Another SPPI report examines the safety of eating fish and concludes:

“The preponderance of the latest scientific literature strongly suggests that at historic

consumption levels we have always been, and will continue to be, safe from the fish we eat.

All sectors of the U.S. population, especially pregnant women, children and the elderly, should

continue deriving critically needed nutrition from fish. There is no sound scientific evidence to suggest that the American public, especially infants and young children, have been exposed to harmful levels of mercury.”

It’s just another phantom menace so scare the people so they demand that government save us.

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3 comments

  1. There is more Mercury coming into modern homes from new technology than from food sources. Easily the worse offender is the compact fluorescent light bulb and fluorescent tubes, These light bulbs are sold as replacements for the biologically harmless tungsten filament light bulb.
    This source of Mercury has every likelihood of entering the food chain via their disopsal in landfill or waste incineration. Recycling efforts for all fluorescent bulb sould happen today, sadly in most places it is not.

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