Natural Fertility and Metals Contents in Soils of Rio Grande do Sul (Brazil)

Abstract

ABSTRACT:The parent geological materials and formation factors influence the chemical, physical, and mineralogical properties and composition of the soil. Therefore, the aims of this study were to determine the chemical and some physical and mineralogical properties of the soil useful for agricultural practice; to determine the natural contents of the semitotal metals in soils of the state of Rio Grande do Sul (Brazil); and to suggest use of the quality reference values (QRVs) in accordance with Resolution 420/2009 of the National Commission for the Environment (Conama). To determine some soil properties useful for agricultural, 254 surface soil samples from areas without known human influence (native grasslands or forests) were analyzed according to the methodology used by the soil testing laboratories of the state of Rio Grande do Sul. In addition, the semitotal heavy metal (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) contents of the soil were determined by the Usepa 3050B method and Hg was determined through an adaptation of the Usepa 7471 method. The results were studied in five soil groups from the state of Rio Grande do Sul according to soil parent materials: (1) basalt (volcanic rocks) of the Plateau region, (2) crystalline rocks (granite, schists, etc.) of the Southern Shield, (3) pelitic rocks (siltstones, mudstones, etc.) of the Peripheral Depression, (4) sandstones (sedimentary) of the Central Plains, and (5) sediments (unconsolidated) of the Coastal Plains. The properties for agricultural use of these soils were compared using the criteria adopted by the current fertilizer recommendations for the state. Multivariate analysis was used to study metals contents. Average values of available P contents were low in all soil groups; however, average values were high in several soil groups for available K. Averages of total acidity and cation exchange capacity were higher in Group 1 soils. The average values of extractable Zn, Cu, and S were high in all soils. Averages of Fe oxides were higher in the soils formed over basalt than in the other soils. Average metal (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) contents were higher in Group 1 soils than in the other soil groups (2 to 5). For Hg, however, average values were similar for all soil groups. The Spearman correlation coefficients were positive and highest among the metals (except for Cd and Hg) and the clay, Fe d , and extractable Cu soil properties. Another high positive correlation coefficient was found between semitotal Cu and Zn contents and organic carbon. The QRVs for Cd, Co, Cr, Cu, Hg, Ni, Pb, V, and Zn, determined according to Conama Resolution 420/2009, followed the same trend as the average metals contents.

Influence of roadways on heavy metal content in soils and yerba mate tissue in southern Brazil

“…However, the range of Cu levels (69-108.32 mg kg -1 ) were below the quality reference value (203 mg kg -1 ) established for basalt Note(s): Significant differences between washed and unwashed plant samples are indicated by different upper-case letters; lower case letters indicate differences between road distances according to ANOVA test followed by Tukey (p < 0.05). The absence of letters represents that there was no difference in the ANOVA test (Althaus et al, 2018). Therefore, observed Cu levels corresponded to natural soil levels associated with parent material.…”

Natural contents of metals in soils from basaltic origins in western Paraná, Brazil

“…A study conducted in Rio Grande do Sul, analyzing soils originated from five different source materials, observed higher Cu and Zn contents in soils derived from basalt (Althaus et al, 2018). These types of soils have higher concentrations of Cu and Zn when compared to others from different lithologies (Hugen et al, 2013).…”

“…Strong correlations suggest similar geochemical behavior in soils from the same source material (Althaus et al, 2018). Freitas et al (2014) analyzed Oxisols under three different uses, and by means of principal component analysis found a strong correlation between Ca, Mg and pH in an environment cultivated with sugarcane; while in a reforested area the correlations were between B, Cu and Zn; and in native forest they were OM, Fe, Al and H+Al.…”

“…The quality guiding values are nothing more than the determination of potentially toxic elements or substances in soils with no direct anthropogenic contribution, which serve as criteria for comparison with soils of similar characteristics. To that end, several Brazilian states have already established their own quality guiding values, including Rio Grande do Sul more recently (Althaus et al, 2018); Minas Gerais (Guevara et al, 2018); Amazonas (Souza et al, 2018) and western Paraná (Bocardi, 2019).…”

Uso Da Termorretificação Para Estabilização Colorimétrica De Três Madeiras Tropicais

“…The soil is formed on materials of geological origin, resulting from the effect of active environmental factors such as climate, position in the landscape and biotic activity for long periods of time (ALTHAUS et al, 2018).…”