Avaliação de risco ecológico associado à presença de agrotóxico na Lagoa de Jacarepaguá - RJ

Abstract

The Jacarepaguá Lagoon (JPAL) is part of the Lagoon Complex of Baixada de Jacarepaguá, being this, one of the largest lagoon complexes in the Rio de Janeiro State occupying an area of 3,7 km2. The JPAL, one of the four lagoons in the complex, gained international visibility after the 2016 Olympic Games with the Olympic Park on its margins. The area has been the focus of intensive investments with urbanization and construction of residential condominiums with decentralized private sewage treatment systems, discharging effluents into the lagoon together with untreated sewage from slums. This study aimed to develop an Ecological Risk Assessment for the JPAL based on Water Quality, Chemical, Ecotoxicological and Ecological Lines of Evidence (LoE). Surface water samples were collected during five bimonthly campaigns at five sampling points in the JPAL. The Index Water Quality LoE based on physical-chemical parameters was used to estimate the Water Quality Risk (0,80±0,07) classified as very high risk (0,75-1,0). The Chemical LoE based on the presence of 107 pesticides was used to estimate the Index Chemical Risk (0,51± 0,20) also classified as high risk (0,5-0,75). The Ecotoxicological LoE based on chronic ecotoxicity assays (C. vulgaris and C. dubia) was used to estimate the Index Ecotoxicological Risk (0,78 ±0,20) classified as very high risk (0,75-1,0). The Ecological LoE based on the analysis of richness and abundance of local algae species was used to estimate the Index Ecological Risk (0,80±0,12) classified as very high risk. Finally, the Index Environmental risk estimated by integrating the risks of the four LoE was 0,81 ± 0,11, being classified as very high risk. It was concluded that LJPA reached an advanced stage of contamination and degradation of its ecosystem, demanding urgent risk mitigation actions, such as the end of clandestine sewage discharge into the lagoon. Further investigation is needed to elucidate the main sources and routes of pesticides found in JPAL with the purpose of preventing them from reaching the lagoon.