Spatial environmental risk evaluation of potential toxic elements in stream sediments

Abstract

Potential toxic elements (PTE), in stream sediments, were used as contamination indicators for the definition of high-/low-grade spatial clusters in the Monfortinho area (Central Portugal). A set of 271 stream sediment samples was used for spatial modelling and further definition of rings of enrichment-high and low rings. A three-step multivariate statistical and geostatistical approach was used: (1) principal components analysis for PTE's association evaluation and dimensionality reduction; (2) ordinary kriging as an unbiased interpolator for content inference and construction of a continuous representation of the considered attributes, at any arbitrary spatial location; (3) G clustering algorithm for the definition of high and low significance clusters. A moderate contamination in stream sediments is observed for almost all the considered PTE and a very high contamination for Ba, Cr and B. High contamination clusters are observed for Fe, Ni, Ba, Cu, B, Zn, V-northwest and southeast clusters-and for Cr-north and southwest clusters. The contamination degree index varies from moderate to high, which is mainly associated with the old mineralizations. The high computed rings often overlap the areas of abandoned Ba-Zn mineralization, as well as the sedimentary gold concentrations, along the Erges River banks. Tin and Cd spatial distribution may be related to former cassiterite exploitations in the survey area. Chromium is possibly connected with the schists. The definition of clusters with a PTE spatial enrichment will allow for the identification of contamination activities and therefore, the definition of adequate monitoring and mitigation actions.

Spatial Mobility of U and Th in a U-enriched Area (Central Portugal)

“…Otherwise, the highest REE, Zn, Cu, Cs, Ba, and Ni contents were found in the soil and reflect geogenic influence associated with the background lithologies from the region. Iron occurred in high concentrations and is associated with the presence of Fe-oxy and hydroxides and the capacity of metals and metalloids adsorption, as found in other mine areas [12,23,24].…”

Pollution Status And Risk Assessment Of Trace Elements In Portuguese Water, Soils, Sediments And Associated Biota: A Trend Analysis From The 80s To 2021

“…As a result, estuaries, rivers and coastal areas are impacted by intensive anthropogenic activities that result in the release of diverse pollutants including trace elements in these compartments. Several works stressed the ecological status regarding the occurrence of trace elements of coastal waters and estuaries, mainly Douro, Mondego, Tejo and Sado (Alves et al 2009, Antunes et al 2018a, Couto et al 2019, França et al 2005, Ribeiro et al 2018. Besides, mining is a relevant economic activity in Portugal, however mining activities are responsible for trace elements pollution of the surrounding environment.…”

Water-Rock Interaction and Potential Contamination Risk in a U-Enriched Area

“…The abandoned U mining sites contain the resulting tailings and discarded materials that have been deposited and discharged into the air and water since those years. After their closure, these mines were abandoned, and some of them were studied to evaluate the impact of environmental radioactivity and potentially toxic elements on human health, e.g., [11][12][13][14][15][16][17][18][19].…”