Assessing the effect of natural variability and human impacts on the environmental quality of a coastal metropolitan area (Montevideo Bay, Uruguay)

Abstract

Montevideo Bay is an extremely polluted coastal system because of multiple sources of contamination from industrial manufacturing, urban activities, energy production, harbor operations and population increase. Because rehabilitation measures will be implemented, this research project was undertaken to assess the contamination of the system. A sediment core that spanned to 3000 yr BP was taken to reconstruct the Holocene natural changes in salinity and trophic state, and also the effect of human activities on the environmental quality of the system. Before the human impact, the system was controlled by a sea level decrease, during which an increase in trophic state was observed. After the human impact, an intensification of the eutrophication process was observed, mainly due to the industrial activities linked to lack of sanitation. In addition, sharp increases in heavy metal concentration were recorded after 1917, when the leather tanning activities together with the construction and operation of the oil refinery and the thermoelectric generation plant were first documented. Thus, the data presented in this paper provide important chronological evidence of human impacts and environmental degradation, which at the minimum can be used to advise the managers and government agencies about the consequences of bad environmental practices on coastal aquatic systems.