Detritivorous fish contamination in the Reo de la Plata estuary: a critical accumulation pathway in the cycle of anthropogenic compounds

Aliphatic hydrocarbons, chlorinated pesticides, polychlorinated biphenyls (PCBs), dioxins, furans, and trace metals have been quantified in fishes collected at four stations in Reo de la Plata to determine contaminant sources, elucidate interstation and interspecies differences, and assess the health risks associated with fish consumption. Reo de la Plata fish present low trace metal concentrations and moderate to high levels of organic pollutants, particularly aliphatic hydrocarbons and PCBs. The highest concentrations were recorded in Prochilodus lineatus, a dominant and remarkably specialized fatty detritivore that feeds on contaminated organic-rich flocculent matter. Lower levels were registered in Cyprinus carpio and especially in Mugil cephalus, reflecting different feeding preferences. A geographical pattern of higher contaminant concentrations close to the Buenos Aires urban center and lower levels in distant stations was also observed. The multivariate analysis of contaminant signatures indicated that most contaminated Prochilodus had fresh petrogenic and PCB traces, similar to fossil fuels and Aroclor 1254-1260, whereas Mugil and fish from distant sites presented a higher proportion of biogenic hydrocarbons and of more chlorinated PCBs. Toxicity equivalents ranged from 11 to 39 pg,g fresh weight(-1) in Prochilodus, exceeding the guideline of 25 pg,g(-1) for human consumption, with allowable consumption rates as low as 1 g fish,day(-1).