Determination of hydrocarbons transported by urban runoff in sediments of São Gonçalo Channel (Pelotas - RS, Brazil)

A high concentration of hydrocarbons in the environment is indicative of pollution. To evaluate the effect of hydrocarbons transported by urban runoff, the present study analyzed total petroleum hydrocarbons (TPHs), aliphatic hydrocarbons (AHs), unresolved complex mixture (UCM), and n-alkanes of the sediments of the canal that cross the urban area of Pelotas, Rio Grande do Sul, Brazil. The carbon preference index (CPI), terrigenous/aquatic ratio (TAR), and pristane/phytane ratio were determined. The TPH content ranged from 177,043.7 μg·kg− 1 ± 13.4% to 5,892,667.0 μg·kg− 1 ± 5.9%. The total aliphatic content ranged from 116,268.8 μg·kg− 1 ± 11.1% to 2,393,592.6 μg·kg− 1 ± 7.7%, indicating chronic contamination of n-alkanes petrogenic and biogenic sources. The levels of hydrocarbons (TPH, AHs, and n-alkanes) were considered relatively high, confirming the effect of urban runoff on the drainage system of cities and their consequent effect on the estuarine region of Patos Lagoon and other water resources.