Mercury spatiality and mobilization in roadside soils adjacent to a savannah ecological reserve

• Published in: Environmental research 2022-04, Vol.205, p.112513-112513, Article 112513
• Main Authors: Rodrigues, Ygor O.S., Dórea, José G., Landim, P.M.B., Bernardi, José Vicente Elias, Monteiro, Lucas Cabrera, de Souza, João Pedro Rudrigues, Pinto, Lilian de Castro Moraes, Fernandes, Iara Oliveira, de Souza, João Victor Villela, Sousa, Antônia Roberto, Sousa, Juruna de Paula, Maciel, Bruno Leandro Oliveira, Delvico, Francisco Marcos dos Santos, de Souza, Jurandir Rodrigues
• Format: Article
• Language: English
• Subjects: Brazilian cerrado; Cokriging; Environmental Monitoring; Humans; Mercury; Mercury - analysis; Mining; Roadside soil; Savannah; Soil - chemistry; Soil Pollutants - analysis
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2021.112513

Mercury (Hg) is a persistent environmental pollutant of global concern. Recognized anthropic contributions to environmental Hg pollution include fuel fossil emissions, soil erosion, and industrial and mining activities. Environmental Hg that enters water bodies can be methylated before entering the food chain and contaminating man and wildlife. We used a kriging approach for sampling and X-ray crystallography to study the pressure of road-traffic Hg emissions on soil Hg concentrations in an ecological reserve (ESECAE) in Central Brazil’ savannah. We took samples of organic (n = 144) and mineral (n = 144) layers from the road-side and from the undisturbed soils at 0.1, 1, and 2 km from traffic, inside the ESECAE. Overall, total mercury (THg) concentrations determined by atomic absorption spectrophotometry were significantly higher in the organic layer than in the mineral layer. The mean soil THg in the organic and mineral layers was highest at the roadside (respectively 19.77 ± 12.01 and 16.18 ± 11.54 μg g−1), gradually decreasing with the distance from the road. At 2 km, the mean soil THg was 0.09 ± 0.30 and 0.029 ± 0.03 μg g−1, respectively, for the organic and mineral layers. X-ray crystallography showed mineralogical similarity of the sampled soils, indicating Hg externality, i.e, it did not originate from existing soil minerals. Co-kriging analysis (n = 288) confirmed Hg hotspots on the roadsides and a faster mobilization occurring up to a distance of 1 km for both layers. The soil reception and retention of traffic Hg emissions are mainly in the organic layer and can impact subsoil and adjacent areas. Thus, traffic soil-Hg pollution is limited to the road proximities; THg concentrations are high up to 100 m with an inflection point at 1 km. [Display omitted] •Traffic Hg emissions and soil contamination were studied up to 2000 m in an ecological reserve.•Soil THg contamination from road vehicles is highest at 100 m and can leach up to 1000 m.•THg is significantly higher in the organic than in the mineral layer of soils.•Geostatistics indicate considerable leaching of Hg within 1 km of road emissions.