Phytotoxicity of surface water of the São Paulo Metropolitan Region using bioassay with Sinapis alba

Abstract

This research aimed to evaluate the phytotoxicity of surface waters of the São Paulo metropolitan region using bioassays based on Sinapis alba L. (mustard). Three sampling campaigns were carried out during the dry season of 2017 (minimum dilution of pollutants) and samples were collected in triplicate at two locations (Reference and Ribeirão Pires stream). The assays were performed in triplicate to increase the degree of reliability of the information obtained. The observed responses were: root growth of S. alba, relative percentage of germination, relative percentage of root growth, Germination Index (GI). Electrical conductivity and total dissolved solids were also measured in situ using a multiparametric probe. The reference samples were classified as non-phytotoxic (IG = 93.55 ± 0.17%), while Ribeirão Pires stream samples showed moderate phytotoxicity (IG = 70.88 ± 0.25%). Thus the discharge from the Ribeirão Pires stream into the billings dam poses a risk to the water quality of the dam, especially where this stream drains.