Modeling Evidence of Episodic Intercontinental Long-Range Transport of Lindane

Two global atmospheric transport models for persistent toxic substances were employed to quantify the intercontinental atmospheric transport of lindane in 2005 using a recently constructed global lindane emission inventory. The focus of this numerical investigation was to identify, on an intercontinental scale, the major sources of lindane that contributed to the contamination of North America and the Arctic. Both models simulated several strong episodic trans-Pacific atmospheric transport events of lindane from its sources in Asia to the western seaboard of North America. Modeling results also detected, for the first time, an important atmospheric pathway for persistent toxic substances from Western Africa/Western Europe to the Caribbean, the southern United States, and the eastern seaboard of North America. Several episodic lindane trans-Atlantic atmospheric transport events were found from May to October, These events were associated primarily with the easterly trade winds and the African easterly wave that extends from the subtropical eastern Atlantic to the Caribbean. This atmospheric pathway for toxic chemicals has a substantial implication for the level of toxic substances in North America. Atmospheric mechanisms contributing to these transport events are briefly discussed. Multiple modeling scenarios were studied to assess the contribution of lindane sources in Europe, Asia, and North America to its fate in the Arctic. Results show that these continental contributions are season-dependent with the highest contribution from Europe in the spring.