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Geoindicators for the Humid Tropics
Report on a Geoindicators Symposium held during the 31st International Geological Congress in Brazil, August, 2000

Antony Berger - IUGS Geoindicator Initiative aberger@uvic.ca

Symposium 23-2, entitled Geoindicators for the Humid Tropics, was convened on August 7 and 8 by Antony Berger (Canada), Lylian Coltrinari (Brazil) and Berardino Figueiredo (Brazil).

Four keynote talks were presented. Robert Morton (US Geological Survey, St.Petersburg, FL) gave a thorough overview of coastal geoindicators with special reference to the Orinoco and San Juan deltas of Venezuela and Colombia respectively. He showed that natural variability in the humid tropics is hard to separate from human-induced changes. Waite Osterkamp (USGS, Tucson AZ) discussed various indicators of river flow and sediment movement and storage, with examples from Puerto Rico. Bernardino Figueiredo (Unversity of Campinas, Brazil) reported his research in progress on arsenic in the Ribeira River of SE Brazil, where he and his colleagues are working to develop models to distinguish natural from anthropogenic inputs. Avijit Gupta (University of Leeds, UK) extended the geoindicator concept to urban areas in the humid and arid tropics, stressing the need to integrate a wide range of environmental indicators in order to assess environmental condition.

In addition, four posters were presented out of the seven accepted. Leonardo Disperati and his colleagues from the University of Sienna, Italy and the Federal University of Parana, Brazil, described on-going research on soil erosion in the Pantanal-Chaco wetlands in south-western Brazil. They are using aerial photos, satellite imagery, and ground surveys to trace changes in land use and soil loss between 1985 and 1996. Noris Diniz (Institute for Technological Research of Sao Paulo State, Brazil) presented a detailed engineering geology map of Sao Paulo state based on an extensive database from which certain geoindicators can be extracted. The poster by Ana Albuquerque and colleagues from the Federal Fluminense University, Brazil) described their research using charcoal particles in lacustrine sediments in three widely separated regions of Brazil to indicate a dry climatic phase during the mid-Holocene.

The presentations ranged widely. It is clear that some special natural conditions apply to the humid tropics - weathering rates, coastal mangroves and coral reefs - but no overall conclusions were evident regarding the geoindicator approach. There are in Latin America a number of current geological monitoring programs as described in other symposia, which could perhaps attract wider attention if placed within a geoindicator framework.

A selection of the presentations in Symposium 23-2 is being submitted to the journal Environmental Geology for publication.

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