ISSUES IN THE MANAGEMENT OF MERCURY WASTES AND WASTESITES

F. R. Anscombe* (USEPA); Jerome O. Nriagu (University of Michigan)

Mercury’s persistence, semi-volatility, atmospheric dispersion, and cycling

within the biosphere presents a waste management challenge. This paper will

discuss inter-related issues pertaining to prudent management of mercury wastes

and waste sites. This paper will not necessarily represent the views or

policies of the U.S. Environmental Protection Agency.

Sequestration of Surplus Mercury: Many OECD nations have greatly reduced

mercury use and have surplus stocks of mercury. Yet many regulations encourage

recovery of mercury and its reintroduction into commerce, increasing exports of

mercury to developing nations. Mercury is unusual as a commodity in that

governments, via subsidies and environmental regulations, are the dominating

source of supply. The environmental justification for recycling is predicated

on diminishing the need for new mining, yet there are no longer active dedicated

private mercury mines in the United States. The U.S. Departments of Defense

and Energy together hold more than 11 million pounds of surplus mercury. Many

other nations will face surpluses from closure of chlor-alkali factories.

Sequestration of mercury to the earth, where principally lodged by Nature, seems

an appropriate policy response for unwanted mercury to minimize environmental

cycling.

Risks from Vapor Emissions: Since 1990, the U.S. EPA has specified incineration

as a treatment for certain mercuric wastes, not factoring risks resulting from

mercury vapor emission. Similarly, various bioengineering teams have reported

on projects to develop plants which have enhanced ability to take mercury up via

roots and to emit it as a vapor via leaves. Similarly, risk assessments and

remedial plans for sites with mercury contaminated soils do not factor mercury

vapor risks, except in terms of worker inhalation exposure. If instead the

risks of mercury vapor were factored in a more holistic consideration of waste

site risks, then alternative remedial designs, both less costly and preferable

in environmental terms, might be chosen.