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Great Lakes Binational Toxics Strategy

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Assessment of Level 1 Substances

SUMMARY OF THE MANAGEMENT ASSESSMENT FOR THE LONG-RANGE TRANSPORT CHALLENGE

Challenge Goal

The GLBTS established a common goal for both the U.S. and Canada, to “Assess atmospheric inputs of Strategy substances to the Great Lakes. The aim of this effort is to evaluate and report jointly on the contribution and significance of long-range transport of Strategy substances from world-wide sources. If ongoing long-range sources are confirmed, work within international frameworks to reduce releases of such substances.”

Since its inception, the GLBTS has addressed this challenge goal by promoting research and discussion and providing a forum for reporting progress on the assessment of the impact of long- range transport (LRT). The most recent of these activities was a two-day workshop on the LRT of Strategy substances, held in Ann Arbor, Michigan, on September 16-17, 2003. Drawing on a commissioned background paper and over 70 experts from around the world, the workshop reviewed the latest research on the global fate and cycling of persistent toxic substances (PTS), identified critical knowledge gaps, and provided recommendations on future activities necessary to adequately address long-range transport. Workshop participants drafted an “Ann Arbor Statement” which contains recommendations aimed at improving our understanding of the LRT of air toxics, particularly with respect to how it impacts the Great Lakes Basin. The Delta Institute presented the final Ann Arbor Statement [PDF 477 13pps] at a conference of the International Association for Great Lakes Research (IAGLR) in May 2004.

The Ann Arbor Statement presents the following conclusions:

Environmental Analysis

There are not sufficient data on the contribution of LRT to fully assess its impact on the Great Lakes Basin. However, current research indicates that LRT, both intra- and inter-continental, may be a significant source of Strategy substances to the Great Lakes Basin.

Recent studies have investigated the LRT of many PTS substances. Mercury modeling has shown that the Great Lakes Basin is not only affected by mercury emissions from North American sources but also that emissions from Asia and Europe make a significant contribution to the mercury burden over the Great Lakes. The presence of lindane in the air in the Great Lakes region and in the North American Arctic can similarly be traced to contributions from both North American and world-wide sources. The major North American source for toxaphene, a legacy chemical, may be the soils of the southeastern U.S. Although, given the prevailing westerly winds, these sources should not affect the Great Lakes, there are certain meteorological situations, lasting only a few days, where there is a direct pathway from these southeastern sources to the Great Lakes. Under these conditions toxaphene air concentrations in the Great Lakes Basin are about two to three orders of magnitude greater than those when the winds are westerly and could be a major factor in the net impact on the Great Lakes Basin.

Researchers at Lawrence Berkeley National Laboratory investigated the North American and global scale transfer efficiency of Level 1 substances to the Great Lakes using the Berkeley-Trent (BETR) contaminant fate modeling framework. The modeling results were used to group substances according to the geographic scale of emissions likely to be transported and deposited to the Great Lakes, with the following results:  1) Local or regional scale: aldrin, dieldrin, and B(a); 2) Continental-scale: chlordane, dioxin, DDT, toxaphene, OCS, and mirex; 3) Northern hemispheric scale: PCBs; and 4) Global scale: HCB and a-HCH. 

Management Assessment

The Ann Arbor Statement identifies a number of actions that are considered to be the most critical scientific and research needs to understand and eventually reduce the LRT of chemicals to the Great Lakes. These actions pertain to emissions inventories, monitoring, modeling, and integration and synthesis. The GLBTS can add value to current efforts by addressing some of these needs through support for: 1) the development of better estimates of the use and emissions of PTS substances both within the Basin and on an appropriate broader scale, 2) air monitoring efforts both in the Basin and in potential source regions upwind of the Basin, 3) improved modeling for informed decision-making, e.g., inter-comparison of models to enhance confidence in the use of such models, 4) investigation of the LRT potential of emerging chemicals, and 5) cooperation with international agencies to reduce emissions at the source.

Two international initiatives, in particular, have a direct impact on reducing the transport of Strategy substances to the Great Lakes. The first is a United Nations Environment Program (UNEP) partnership looking at the fate and transport of substances, primarily mercury. The second is a pesticide initiative in which Canada, the U.S., and China are investigating lindane usage in China and the China-Pacific transport pathway. It is important that the GLBTS participate with these initiatives to further the interests of the Great Lakes region.  In addition, implementation of the Stockholm Convention by individual countries will lead to reduced uses and releases of a number of persistent organic pollutants, which should also lead to reduced loadings from other countries to the Great Lakes. 

Management Outcome

The current challenge goal for LRT remains relevant, and no changes are recommended at this time. The GLBTS will continue to:

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