Tracking Anthropogenic Inputs in Barigui River, Brazil Using Biomarkers

The Barigüi River watershed is located in the metropolitan region of Curitiba, Southern Brazil, passing through several neighboring counties. In recent years, due to growth and disorderly occupation along the river, in addition to lack of sanitation, the Barigüi River suffered a very large inflow of untreated domestic wastewater. Current programs to monitor the watershed use traditional physical–chemical parameters. Here, the presence of some molecular tracers found in domestic effluents was investigated, such as caffeine and coprostanol at some selected sites in Barigüi River. Caffeine is highly soluble in water and its presence in water bodies is due to the disposal of untreated sewage. Caffeine is eliminated in the urine (approximately 0.5% to 10% of the consumption). The samples were collected in three campaigns, two in dry weather and another during a week in the rainy season. The results showed that caffeine concentration ranged between zero and 753.5 μg g^?1. Higher values were found on rainy days. Caffeine showed a positive correlation between BOD and nitrate; it also showed a positive correlation with coprostanol, a fecal biomarker. Finally, caffeine has been shown to be a good parameter to determine the contamination by domestic wastewater.