Health risk assessment and soil and plant heavy metal and bromine contents in field plots after ten years of organic and mineral fertilization.

Heavy metals and bromine (Br) derived from organic and industrialized fertilizers can be absorbed, transported and accumulated into parts of plants ingested by humans. This study aimed to evaluate in an experiment conducted under no-tillage for 10 years, totaling 14 applications of pig slurry manure (PS), pig deep-litter (PL), dairy slurry (DS) and mineral fertilizer (MF), the heavy metal and Br contents in soil and in whether the grains produced by corn (Zea mays L.) and wheat (Triticum aestivum L.) under these conditions could result in risk to human health. The total contents of As, Cd, Pb, Cr, Ni, Cu, Zn and Br were analyzed in samples of fertilizers, waste, soil, shoots and grains of corn and wheat. Afterwards, enrichment factor (EF), accumulation factor (AF), health risk index (HRI), target hazard quotient (THQ) and target cancer risk (TCR) were determined. Mineral fertilizer exhibited the highest As and Cr content, while the highest levels of Cu and Zn were found in animal waste. The contents of As, Cd, Cr, Cu, Ni, Pb and Zn in soil were below the limits established by environmental regulatory agencies. However, a significant enrichment factor was found for Cu in soil with a history of PL application. Furthermore, high Zn contents were found in shoots and grains of corn and wheat, especially when the plants were grown in soil with organic waste application. Applications of organic waste and mineral fertilizer provided high HRI and THQ for Br and Zn, posing risks to human health. The intake of corn and wheat fertilized with pig slurry manure, swine deep bed, liquid cattle manure and industrialized mineral fertilizer did not present TCR.

Environmental vulnerability and phosphorus fractions of areas with pig slurry applied to the soil.

The application of pig slurry as a fertilizer can cause soil and water contamination. Intrinsic characteristics of the environment may enhance this effect and influence the vulnerability of the agricultural system. The goal of this study was to evaluate the accumulation of soil P fractions in areas treated with pig slurry and in forest areas and to propose an evaluation of the areas' vulnerability to P contamination. Soil samples were collected from 10 areas with pig slurry applied to the soil and one in forest without a history of pig slurry application, all located in the Coruja and Bonito rivers microbasin at Braço do Norte, Santa Catarina, southern Brazil. Samples were prepared and subjected to P chemical fractionation. Two versions of the P index method, based on soil P forms or only on P extracted by Mehlich-1, were used to evaluate the environmental risk of the studied areas. Estimated soil losses were lower for the forest and natural pasture and highest in areas with black oat ( Schreb.)-corn ( L.) crop cultivation. Concentrations of P fractions, especially of organic and inorganic P extracted by 0.1 and 0.5 mol L NaOH and NaHCO and of inorganic P extracted by anion exchange resin and HCl, were higher in areas with a longer history and higher frequency of pig slurry applications. Vulnerability to P contamination was mainly influenced by soil P concentrations and soil losses in the studied areas. The P index based on Hedley's fractionation P forms resulted in a more accurate risk scoring of the studied areas than the P index based on the concentration of available P extracted by Mehlich-1.