Heavy metal contents in Latosols cultivated with vegetable crops1

Abstract

Heavy metals are naturally found in soils, but their levels may increase as a result of anthropogenic actions. This study aimed at determining the concentrations of Cd, Cu, Mn, Ni, Pb and Zn in Yellow Latosol from vegetable crops areas, as well as the influence of the cultivation and position in the landscape on the accumulation of these elements. Soil samples were collected from five farming areas and four areas with natural vegetation, which served as a reference. Soil was collected along the planting rows from three transect positions (upper, middle and lower sections of the slope), as well as from the upper portion of forest areas, at three depths (0.0-0.10 m, 0.10-0.30 m and 0.30-0.60 m). The results from the chemical analyses indicated that Cd, Cu, Mn, Pb and Zn levels in the soil increased as a result of cultivation. Only Cd and Cu concentrations were above the quality reference values for the Pernambuco State. The multivariate analysis techniques used were efficient at separating the environments and at differentiating the origin of the metals. Soils from forest areas were clearly separated from croplands, demonstrating the effect of agricultural practices on the metal contents in the soils. The principal component analysis indicated a predominantly anthropogenic origin (phosphate fertilizing) for Cd, in more superficial soil samples.

Chemical Changes of Soil and Water in Hillside Areas Under Intensive Horticulture

“…Soils from forest areas have a higher OM content, which is in accordance with several studies that compare changes in soil chemical attributes attributed to agricultural practices in comparison to natural areas (Portugal et al, 2010;Silva et al, 2016). The highest OM contents in native vegetation areas are explained by the greater contribution of organic residues (Portugal et al, 2010) since the anthropic interference, such as the use of agricultural implements and cultural practices, accelerates OM degradation (Freitas et al, 2015).…”

“…By means of the factor and principal components analyses, Coletti et al (2010) concluded that substances of ammonia, ammoniacal nitrogen, and nitrate from agricultural activities were the main contaminants of water resources. In the study of Silva et al (2016), the application of these analyses not only discriminated the enrichment sources of OM, P, and heavy metals in vegetable cultivation but also elected and revealed the decisive factor for distributing these variables along the hillside of an Oxisol. In short, multivariate statistics allows a greater capacity to describe intra-and interdependence relationships in agricultural systems, allowing establishing and planning more appropriate management practices.…”

Fractionation of heavy metals in yellow latosol cultivated with vegetables

“…The worldwide increase in anthropogenic, industrial and agricultural activities is responsible for the growing release of different pollutants into the environment (KABATA-PENDIAS, 2010;MACEDO et al, 2012;SILVA et al, 2016). Heavy metals such as cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), zinc (Zn) and lead (Pb) are the most well-known and cause significant damage to the environment and human health.…”

“…Heavy metals such as cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), zinc (Zn) and lead (Pb) are the most well-known and cause significant damage to the environment and human health. Farming in soils that are subject to intensive fertilizer and pesticide application and poor quality irrigation water (SILVA et al, 2016) are the main entry routes for these metals into human and animal diets (CHANEY;OLIVER, 1996;FERNANDES et al, 2007;CONAMA, 2009;ATSDR, 2011).…”

“…In the soil, these metals can be found in different chemical forms and at concentrations that are not fully available to plants SINGH, 2001). Some authors have reported that the concentration and distribution of metals in soil depends primarily on the geochemical nature of the parent material SZERSZEN, 2002;BIONDI et al, 2011;ALMEIDA JÚNIOR et al, 2016;SILVA et al, 2016). In turn, their potential toxicity and mobility are heavily influenced by the intensity of adverse weather conditions, soil mineralogy, pH, and cation exchange capacity (CEC), as well as the texture and content of the parent material (HAN et al, 2001;NACHTIGALL et al, 2009;LIMA et al, 2013).…”