Recovery and Distribution of Biosolids‐Derived Trace Metals in a Clay Loam Soil

Abstract

The long-term mobility of trace metals has been cited as a potential hazard by critics of EPA 503 rule governing the land application of biosolids. The objectives of this study were to assess the accumulation of Cu, Ni, Cd, and Zn within the soil profile; the distribution of exchangeable, specifically adsorbed, organic, and oxide fractions of each metal; and mass balance of Cu, Ni, and Zn 17 yr after a single biosolids application. Biosolids were applied to 1.5- x 2.3-m confined plots of a Davidson clay loam (fine, kaolinitic, thermic Rhodic Kandiudult) in 1984 at 0, 42, 84, 126, 168, and 210 Mg ha(-1). The highest biosolids application supplied 4.5, 750, 43, and 600 kg ha(-1) of Cd, Cu, Ni, and Zn, respectively. Soils were sampled to a depth of 0.9 m and sectioned into 5-cm increments after separating the Ap horizon. Total (EPA-3050B), bioavailable (Mehlich-I), sequential extraction, and dispersible clay analyses were performed on samples from the control, 126 Mg ha(-1), and 210 Mg ha(-1) treatments. Trace metals are still concentrated in the top 0.2 m with slight enrichment down to 0.3 m. More than 85% of applied Cu, Ni, and Zn are still found in the topsoil where biosolids was incorporated and 95% or more of the applied metals were accounted for with mass balance calculations. Mehlich-I results showed a slight increase in metal concentration down to 0.35 m. Biosolids application increased the concentrations of trace metals in all the extracted fractions. The major portions of Cu, Zn, and Ni are associated with the metal-oxides fraction. Dispersible clay content and water-soluble metal contents were low and except for water-soluble Zn they were not affected by biosolids application. Results from this study showed that 17 yr after biosolids application there was negligible movement of trace metals through the soil profile and consequently there is little risk of contamination of ground water at this site.

Residual effect of sewage sludge fertilization on sunflower yield and nutrition

“…These results differ from those reported by Oliveira et al (2005), who observed residual effect for Zn, which tended to remain in the layer of 0-20 cm. Sukkariyah et al (2005) observed that, after 17 years of cultivation, more than 75% of Zn and 85% of Cu applied through sewage sludge fertilization remained in the layer of incorporation, which is not desirable, because of the possibility of reaching phytotoxic levels. Among the micronutrients evaluated in this study, only B showed contents classified as low and very low (Alvarez V. et al, 1999) in the layers of 0-20 and 20-40 cm, respectively (Table 4).…”

Sewage Sludge Disposal and Applications: Self-heating and Spontaneous Combustion of Compost Piles - Trace Metals Leaching in Volcanic Soils After Sewage Sludge Disposal

“…On the other hand, it has been widely recognized through biochemical and toxicological studies that the environmental impact of heavy metal pollution can be related to soluble and exchangeable fractions that determine bioavailability, mobility, and toxicity in soils (Rauret, 1998;Lock & Janssen, 2001;Guo et al, 2006a). In soils with a mineralogy dominated by crystalline compounds and with lower organic matter content than volcanic soils, it has been found that a negligible movement of trace metals through the soil profile occurred after 17 years of sludge application (Sukkariyah et al, 2005), and Chang (Chang et al, 1984) found that >90% of metals such as Cd, Cr, Cu, Ni, Pb, and Zn added in that way remained in the surface layer (0-0.15 m) after 6 years. Unlike others contaminants, most metals do not undergo microbial or chemical degradation in the soil; therefore, metal concentrations will remain without significant changes for long periods of time (Guo et al, 2006b).…”

Assessing the effect of long-term crop cultivation on distribution of Cd in the root zone

“…There were number of field investigations on the profile distributions of Cd after the soils had received multiple year applications of P fertilizers and sewage sludge (Gray et al, 1999;Rattan et al, 2005;Sukkariyah et al, 2005). Their fate in the cropland soils is influenced by an array of interactive and simultaneous processes, including input from various sources; chemical reactions between the solution and solid phases; removals by crop uptake and harvest; partial re-deposition through residue incorporation; transport by applied water; etc.…”