Project:

North American Soil Geochemical Landscapes

The U.S. Geological Survey (USGS), Geological Survey of Canada (GSC), Agriculture and Agri-Food Canada, Servicio Geológico Mexicano (SGM), and Instituto Nacional de Estadística Geografía e Informática (INEGI) are collaborating on a project titled North American Soil Geochemical Landscapes, whose long-term goal is a soil geochemical survey of North America. Our current understanding of the variability in chemical composition of the soils on the North American continent is very limited. Neither Canada nor Mexico has a national-scale soil geochemical database, and the most-often-quoted data set for estimating background concentrations of metals in soils of the conterminous United States contains only 1,323 samples (1 sample per 2,300 square miles). As a result, the ability to recognize and quantify changes to soil composition caused by urbanization, industrialization, agriculture, mining, waste disposal, and other human activities is severely impaired. For additional background information see USGS Fact Sheet 2006-3115 (http://pubs.usgs.gov/fs/2006/3115/) and the Geochemical Landscapes Project web site (http://minerals.cr.usgs.gov/projects/geochemical_landscapes/index.html).

On November 11-15, 2007, the Servicio Geológico Mexicano (SGM) and the National Autonomous University in San Luis Potosi (UASLP), including the Centro de Estudios, Assesorias y Servicios en Sistemas Ambientales (CEASSA within UASLP) hosted members of the project from the GSC and the USGS in San Luis Potosi. The meeting included discussions about soil sampling protocols and analytical techniques to be used for the project. A field excursion to a soil pit near Real de Catorce provided the opportunity to ensure consistent classification and collection of soil horizons.

As a result of the meeting, areas in each country were identified that require re-sampling to ensure consistency between all of the data collected.

In October 2008, a topical session at the Geological Society of America annual meeting in Houston, TX will highlight advances being made in the Tri-National soil geochemistry survey project.