Can the environmental health of urban centers be assessed through pollutants trapped in lakes? A study case in the biggest city of the southern hemisphere.

Air and water quality in urban centers are summited to pollution from different sources, such as industrial activities, traffic, and wastewater effluents. A great number of chemicals can be spread by wind throughout the city, exposing the inhabitants to the health risks associated to them. Atmospheric analysis provides punctual data and represents the timing of the air sampling. A long-term evaluation of the atmospheric air quality can be assessed through the evaluation of pollutants that reach the soil by atmospheric deposition; however, they also can be redistributed and desorbed. The evaluation of pollutants in lakes could be a practical solution, given that lakes may act as traps to these compounds. In this context, organic pollutants were assessed in sediment and water from a lake located in the urban area of São Paulo, Brazil, the biggest city of the southern hemisphere. There were no evidences of sewage input to the lake and pyrogenic compounds reached the lake through atmospheric deposition. The content of pyrogenic PAH exposed the large amount of PAH emitted to the atmosphere by the multiple sources of PAH, mainly vehicular emission and diesel combustion. The PAH trapped in the lake highlighted the impact of all burning process in the air quality in which 12.3 million people are exposed.