Sources and Variations of Mercury in Tuna

The Scientific Paper:

A. M. Kraepiel, K. Keller, H. B. Chin, F. G. Malcom, and F. M. Morel. Environmental Science and Technology Vol. 37. No. 24. pp. 5551-5558. 2003.

Review This Scientific Paper’s Abstract:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db
=PubMed&list_uids=14717163&dopt=Abstract

The Purpose of this Study:
These scientists attempt to understand where mercury is entering the seafood chain:

1. in the waters; and/or
2. in the atmosphere.

Some Background, Methods, Results, Caveats, and Other Select Points:

• This peer-reviewed, scientific paper was published in 2003.
• While most people are exposed to methylmercury by eating saltwater fish, most of what science knows about how methylmercury is created and then accumulates in fish, mammals, and elsewhere comes from freshwater studies - and not from seawater studies.
• Science knows very little of where and how methylmercury is formed in the oceans. There is also a debate in 2003 about whether methylmercury levels in saltwater fish have increased along with global manmade mercury emissions – such as burning coal.
• Methylmercury levels measured in Yellowfin tuna caught off Hawaii in 1998 show no increase compared to methylmercury levels of the same species caught in the same area in 1971.
• In 2003 methylmercury is believed to form in the deep waters and/or in the sediments on the bottom of the oceans.
• The little science on methylmercury in the oceans does not provide a sound basis for determining the sources and/or concentrations of methylmercury.

A Bottom Line:

• These scientists believe that methylmercury is formed in the deep waters and/or in the sediments on the bottom of the oceans where manmade mercury emissions have little effect(s).
• These scientists’ conclusion about where methylmercury is formed and/or concentrated rests ultimately on the simple idea that if mercury in tuna originated wholly or partly in the air, the increase in mercury in the air should have been reflected to a measurable extent in the methylmercury found in fish caught in 1971 and compared to the same type of fish caught in the same part of the ocean some 27 years later in 1998.
• The fact that the methylmercury concentrations in tuna are identical in 1971 and 27 years later in 1998 either:
  1. reflects a remarkable coincidence; or
  2. indicates that, regardless of how methylmercury is formed and/or stored, the methylmercury levels in tuna are not responding to the additional mercury pollution being released into the air.

Find This Scientific Paper for Your Review:
Sources and Variations of Mercury in Tuna. Environmental Science and Technology Vol. 37. No. 24. pp. 5551-5558. 2003.