Deterioration of extrafloral nectaries and leaf damages caused by air pollution in a Brazilian native species from the Atlantic Forest

In Brazil, more than 90% of steel mills are located in states that have Atlantic Forest which, together with the pollution of large urban centers, represent risk factors for the environmental quality of this important biome. The aim of this study was to evaluate the effects of urban and industrial air pollution in a city in Minas Gerais that has a steel mill on the symptomatology, on the leaf chemistry, and on the anatomy and micromorphology of extrafloral nectaries (EFNs) of Joannesia princeps Vell. (Euphorbiaceae), a native species of the Atlantic Forest. For 126 days, seedlings of J. princeps were exposed on stand systems in the urban and industrial area of MG (Ipatinga city), in the following places: Bom Retiro, Cariru, Cidade Nobre, and Veneza. For anatomical analysis, EFNs were collected and processed for microscopic analysis. In the southern parts of the steel mill closest to the Rio Doce State Park (RDSP) (Bom Retiro and Cariru), there was a predominance of NO, NOX, SO2 (Bom Retiro), naphthalene, benzene, and total suspended particulates (Cariru). In locations north of the steel mill (Cidade Nobre and Veneza), there was a predominance of volatile organic compounds (VOCs). In the urban environment, intense anatomical and micromorphological damage to EFNs, leaf damage, leaf metal accumulation, and alterations in the histochemical tests of the plants were observed. The interior of the RDSP presented environmental quality, but the contribution of pollutants near the border between the RDSP and the city of Ipatinga is worrying, requiring constant monitoring of this area to verify the impact and threat that pollution can cause on these Atlantic Forest remnants.