Large-Scale Agriculture and Environmental Pollution of Ground and Surface Water and Sediment by Pesticides in the Brazilian Amazon: the Case of the Santarem Region

The current development model of the agricultural sector in Brazil has considerable potential to cause negative environmental impacts, including the pollution of aquatic ecosystems, as it may contribute to the intensification of erosive processes on deforested soils, to the leaching of eroded materials, and to the consequent siltation of waterbodies with soil particles containing environmental pollutants. We aimed at assessing the occurrence of several pesticide residues in aquatic ecosystems located near large soybean crops of the Santarem region, in the eastern Brazilian Amazon. By adopting a methodological approach combining analytical and environmental chemistry, 10 groundwater samples, 18 surface water, and 15 drainage bottom sediment samples, all collected in streams from the study region, were analyzed. The study included a distributed sampling procedure covering an area of approximately 20 km(2), and the potential risks of the studied pollutants and their implications for the region were likewise examined and critically discussed. Results indicate that active ingredients such as the herbicides atrazine and metolachlor were detected in the waters, as well as organochlorine insecticides such as DDTs and endosulfan. The spatialization of the resulting pesticide concentrations in water suggests that the contamination would not be punctual but would rather come from various point sources. As for the sediments, glyphosate and DDT contamination was likewise pervasive. Our findings suggest the need of elucidating the sediment and water polluting effects of large-scale soybean crops in the Amazonian rainforest.

Automated summary

The current development model of agriculture in Brazil may lead to negative environmental impacts, including pollution of aquatic ecosystems. A study in the Santarem region of the Brazilian Amazon found pesticide residues in water and sediment samples near large soybean crops. The presence of herbicides and organochlorine insecticides suggests the need for further research on the pollution effects of large-scale soybean crops on the Amazon rainforest.