Integrated Geochemical Assessment of Soils and Stream Sediments to Evaluate Source-Sink Relationships and Background Variations in the Parauapebas River Basin, Eastern Amazon

Abstract

This study aims to handle an integrated evaluation of soil and stream sediment geochemical data to evaluate source apportionment and to establish geochemical threshold variations for Fe, Al, and 20 selected Potentially Toxic Elements (PTE) in the Parauapebas River Basin (PB), Eastern Amazon. The data set used in this study is from the Itacaiúnas Geochemical Mapping and Background Project (ItacGMBP), which collected 364 surface soil (0–10 cm) samples and 189 stream sediments samples in the entire PB. The <0.177 mm fraction of these samples were analyzed for 51 elements by ICP-MS and ICP-AES, following an aqua regia digestion. The geochemical maps of many elements revealed substantial differences between the north (NPB) and the south (SPB) of PB, mainly due to the geological setting. The new statistically derived threshold values of the NPB and SPB regions were compared to the threshold of the whole PB, reported in previous studies, and to quality guidelines proposed by Brazilian environmental agencies. The natural variation of geochemical background in soils and stream sediments of PB should be considered prior to defining new guideline values. At the regional scale, the local anomalies are mostly influenced by the predominant lithology rather than any anthropogenic impact.

Geochemical investigation of gold and chalcophile minerals of Rawayau Area Katsina State, Nigeria

“…According the Salomao et al, (2021), there are three main methods adopted by researchers in estimating geochemical threshold values: the Median + 2 * Median Absolute Deviation (Med. + 2 * MAD), the Tukey's Inner Fence (TIF) and the Percentile Based approaches of which the Median + 2 * Median Absolute Deviation is mostly used.…”

Methodological approach and general guidelines to geochemical mapping and background-baseline analysis for environmental assessment: a case study in the Carajás Mineral Province, Brazil

“…The color soil maps of ItacGMBP were prepared in the QGIS Web front-end and are based on a grid calculation using ordinary kriging for interpolation and carried out cross-validation procedures, following the mapping approach of other continental-and regional-scale baseline geochemical studies (Filzmozer et al 2014). Geochemical maps were constructed based on several techniques (Carranza 2011, Cheng et al 2014, Salomão et al 2021): point representation, the graduated symbols were based on the percentile-based approach of data distribution, defining five classes that were distinguished with different shapes; using inverse distance weighting (Midwood and Chow-Fraser 2010) interpolation; and catchment-based representation of uni-element concentrations for transported materials data (surface water and stream sediments). For instance, Figure 10 shows the geochemical distribution map of Fe in the IRW following the different methods described previously.…”

“…The geochemical distribution maps were fundamental to the evaluation of regional geochemical patterns and the identification of concentrations above the regional background. For more information about the regional interpretation of the elements in the IRW, refer to Sahoo et al (2019bSahoo et al ( , 2020b and Salomão et al (2020Salomão et al ( , 2021.…”

“…In soils and sediments, the concentrations of Al and Fe are expressed in % and the remaining elements in mg/kg. In surface water, only the total concentration was determined; the concentrations of Al, Fe, and Mn are expressed in mg/L and the remaining elements in μg/L; a values presented inSahoo et al (2020b); b values presented inSalomão et al (2020Salomão et al ( , 2021; c values presented inSahoo et al (2019b).…”

Geochemical assessment of soil and water in two protected areas from Valcea and Dolj Counties

“…The natural variation of the geochemical background in soil and river sediments should be considered before defining new indicative values. At the regional level, local anomalies are influenced by the predominant lithology rather than any anthropogenic impact [3][4][5][6]. Protected areas are the most common and important tool for the conservation of biological diversity and are required under the United Nations Convention on Biological Diversity.…”