Avaliação da contaminação por metais pesados em solos urbanos da Região Metropolitana do Recife: bioacessibilidade e correlação com NDVI

Abstract

Urban pollution by heavy metals is a subject of great socio-environmental relevance due to its potential deleterious effects on human and ecological health. Remote sensing, particularly the use of the Normalized Difference Vegetation Index (NDVI), emerges as a promising tool to assess vegetation health and potential impacts of soil contamination. In this regard, the present study aimed to evaluate the total contents and bioaccessibility of heavy metals in urban soil of the Recife Metropolitan Region and its chemical characteristics, obtain the NDVI of the sampled areas, and correlate it with the total metal contents analyzed. The research was conducted in the Recife Metropolitan Region (RMR), where samples of surface soil were collected in distinct urban areas and their points were georeferenced. The samples were analyzed for pH values, Organic Carbon, Soil Cation Exchange Capacity (CTC), and total heavy metal contents using Energy Dispersive X-ray Fluorescence (pXRF). Metal contents were compared with Quality Reference Values, and in vitro assays were performed to determine metal bioaccessibility in the soil. For NDVI estimation, images obtained from the CBERS-4A satellite with 8m spatial resolution were used, and buffers with radii of 55, 110, and 220m were applied to demarcate the area to be analyzed based on the sampled points. The results revealed high levels of heavy metals in urban areas of the RMR, exceeding the Quality Reference Values for the state of Pernambuco, yet the metals exhibit low bioaccessibility. Regarding the size of the analyzed area, there was no significant difference in relation to the values obtained. Additionally, a negative correlation was observed between most soil metal contents and NDVI, meaning that as NDVI increases, metal contents decrease.