Valoração do custo social do estoque de carbono em manguezais em diferentes estágios sucessionais no Estado de Sergipe

Abstract

Mangroves are coastal ecosystems that play a fundamental role in maintaining biodiversity and providing essential ecosystem services, standing out for their high capacity for blue carbon sequestration and storage. In this context, thisstudy aimed to quantify carbon stocks and evaluate metal concentrations in mangrove sediments at different successional stages in the state of Sergipe, Brazil, as well as to estimate the economic valuation associated with stored carbon. Sediment samples were collected from three mangrove areas at two depths (0–10 cm and 10– 20 cm), totaling 24 subsamples. Organic carbon was determined using the wet sulfocromic method based on the modified Walkley-Black procedure, while metal quantification was performed after microwave-assisted acid digestion followed by multielement determination using ICP-OES. Carbon stock was estimated based on bulk density, analyzed layer depth, and organic carbon content, subsequently converted to Mg C ha⁻¹ and used to estimate the social cost of carbon. The results indicated that concentrations of potentially toxic elements, such as As, Pb, Co, Cu, Cr, Ni, Zn, and Ag, remained below the Prevention Values established by CONAMA Resolution No. 420/2009 at all evaluated sites and depths. Regarding carbon stocks, the Areia Branca area presented the highest values (32.70 and 33.20 Mg C ha⁻¹ in the 0–10 cm and 10–20 cm layers, respectively), while Nossa Senhora do Socorro showed the lowest values (18.80 and 18.90 Mg C ha⁻¹). Consequently, the highest estimated values for the social cost of carbon were observed in Areia Branca (up to US$ 5,852.56 ha⁻¹), whereas the lowest values occurred in Nossa Senhora do Socorro (up to US$ 3,321.71 ha⁻¹). The results demonstrate that mangrove areas with better conservation conditions and greater structural development tend to present a higher carbon storage capacity, highlighting the relevance of these ecosystems for climate change mitigation. Therefore, the study reinforces the importance of mangrove conservation and sustainable management, considering their ecological, climatic, and socioeconomic roles.