Chemical Changes and Heavy Metal Partitioning in an Oxisol Cultivated with Maize (Zea mays, L.) after 5 Years Disposal of a Domestic and an Industrial Sewage Sludge

Abstract

The need for solutions to minimize the negative environmental impacts of anthropogenic activities Fhas increased. Sewage sludge is composed of predominantly organic matter and can be used to improve soil characteristics, such as fertility. Therefore, its application in agriculture is an adequate alternative for its final disposal. However, there is a lack of information on its long-term effects on soil changes in tropical areas. Thus, the objectives of this study were to determine (i) the effect of sewage sludge application on heavy metal build-up in soil and maize grains and leaves, and (ii) the effects of soil amendment with sewage sludge on the chemical properties of a Brazilian oxisol. Besides the increasing levels of Zn, Cu, Ni, and Cr, amending soil with sewage sludge also alters the distribution of these metals by increasing the mobile Phases, which correlated significantly with the increase in metal extraction with two single extractants, Mehlich 1 and DTPA (Diethylene triamine pentaacetic acid). The levels of Fe, Mn, Zn, and Cu in maize grains and leaves increased with the type and rate of sewage sludge application. Nevertheless, metal build-up in soil and plants was within the allowed limits. Significant differences were also found in soil characteristics like humic fractionation with the applied sewage doses. The data obtained does not indicate any expressive drawbacks in the use of sewage sludge as a soil amendment, as the heavy metal concentrations observed are unlikely to cause any environmental or health problems, even overestimated loadings, and are in accordance with the Brazilian regulations on farming land biosolid disposal.

Relationship between organic matter humification and bioavailability of sludge-borne copper and cadmium during long-term sludge amendment to soil

“…From 2007 to 2014, many studies have reported the heavy metals risk associated with the amendment of sludge to soil (Alcantara et al, 2009;Antoniadis et al, 2007;Brazauskiene et al, 2008;Carbonell et al, 2009;Lag-Brotons et al, 2014;Oladeji et al, 2012;Yeganeh et al, 2010). However, there is certain boundedness on the conclusions obtained by these researchers mentioned above.…”

Risk simulation of soil contamination by polycyclic aromatic hydrocarbons from sewage sludge used as fertilizers

“…15 Sewage sludge used as fertilizers might contaminate crops, soils, superficial and underground waters with nitrates, heavy metals, pathogens, various classes of organic compounds and persistent organic compounds. 14,16,17 In Brazil, the use of SS in agriculture is regulated through the directive CONAMA357/2005. 18 There is little information in the literature about PAH uptake by plants from SS-treated soils.…”

“…Soil samples were obtained from a field experimental area of Embrapa Meio Ambiente (Embrapa Environment), where a long-term experiment was carried out with corn plants grown in soils amended with SS for six consecutive years. 11,14,26 Experimental Field experiments were carried out in a clay texture distroferric red oxisol (sand loam rhodic oxisol, typic Nine experimental plots of 10 × 20 m cultivated with corn plants were used. The experiment was arranged in randomized complete blocks with three replications.…”

“…11 However, there are risks and benefits associated with SS use in soils, since it contains not only OM, N and P, but also metals, microorganisms and pollutant organic compounds such as the PAHs. [12][13][14] In general, the pollutant substances are associated with uncontrolled mixtures of domestic and industrial wastes or with the waste treatment process. 15 Sewage sludge used as fertilizers might contaminate crops, soils, superficial and underground waters with nitrates, heavy metals, pathogens, various classes of organic compounds and persistent organic compounds.…”

“…Soil samples were obtained from a field experimental area of Embrapa Meio Ambiente (Embrapa Environment), where a long-term experiment was carried out with corn plants grown in soils amended with SS for six consecutive years. 11,14,26 …”