Epsilon Archive for Student Projects

Abstract

A screening of pesticides in different environmental compartments was performed in rivers of a protected Atlantic rain forest reserve, Parque Estadual Turístico do Alto Ribeira (PETAR). PETAR is located in Ribeira Valley, which is a poor and less developed region in the southern part of the State of São Paulo, Brazil. PETAR is affected by different human activities both inside the reserve and in the surroundings. In the watershed of the rivers draining the reserve there are plantations with tomato as main cash crop. Pesticides are used to a large extent and have been detected in river water sampled in PETAR in 1998 and 1999. In addition to water, this study also includes river sediment and fish muscle tissue. A sampling survey was conducted during the wet season in Betari, Iporanga and Pilões River and small tributaries in their watershed in mid-January 2000. Altogether seven different sites were visited. Two species of bottom dwelling catfish (Order Siluriforme) were selected for the study. One is a carnivorous-insectivorous and piscivorous species called bagre (Rhamdioglanis frenatus, Family Pimelodidae) and the other is a primary consumer called cascudo (Isbrueckerichthys sp. Family Loricariidae). The samples were analysed on GC-ECD/NPD after extraction and clean-up. Pesticides were detected in samples from all the sites examined and the fish have even accumulated some of the more persistent pesticides or metabolites. In all, 27 different pesticides or metabolites were detected. In the screening of water, 106 pesticides were included and 16 were found in the samples. A few of them are considered highly toxic to fish and other aquatic organisms. The sediment was screened for 27 organochlorine compounds (OCs) and pyrethroid pesticides and 14 OCs were included in the study of fish. Seven OCs were found in sediment and ten OCs in fish. Fish from two small streams in Iporanga and Betari watershed seemed to be more contaminated than the other sites and sediment samples from the same Betari tributary contained the highest number of pesticides found in sediment. The results show that the aquatic flora and fauna of PETAR are exposed to pesticides both dissolved in the water and in the sediment. There may be a risk that pesticides in the water reach levels that stress the organisms and cause adverse effects on the aquatic ecosystem. However, it is difficult to quantify the risk to biota exposed since several different stress factors affect them simultaneously and synergistic or antagonistic effects cannot be excluded.