Cadmium, copper, and chromium levels in maize plants and soil fertilized with sewage sludge

Abstract

The use of sewage sludge as fertilizer is a widespread practice. However, the presence of heavy metals and pathogens in sludge are a cause for concern. The objective of this study was to determine the levels of cadmium (Cd), copper (Cu), and chromium (Cr) in leaves, aerial parts, and kernels of maize grown in red latosol that was fertilized with sewage sludge for 15 consecutive years. Metal concentrations in soil and kernel yield were also determined. A randomized block design was used, with five replicates and four treatments: T1, mineral fertilization (control); T2, application of sewage sludge at 5 Mg ha−1; T3, application of sewage sludge at 10 Mg ha−1; and T4, application of sewage sludge at 20 Mg ha−1. All plots received potassium (K) supplementation. Fertilization with sewage sludge was as efficient as mineral fertilization. Sewage sludge had no negative effect on kernel yield. A negative correlation was observed between metal concentrations in soil and plant samples. Cd was detected at ≤0.04 mg kg−1 in kernels and Cu at ≤2.34 mg kg−1, whereas Cr was not detected in any sample. These levels are considered safe for human consumption, according to the Brazilian Health Regulatory Agency. Fertilization with sewage sludge for 15 years did not increase Cu, Cd, and Cr levels in the soil and had no negative effect on maize, which shows the potential of sewage sludge for agricultural use.

A comparison of selected heavy metals in soils mixed with domestic and industrial sludges and assessment of effects of the sludge pollutants on oxidative stress markers of the African kale (Brassica oleracea var acephala) grown using sewage sludge manure

“…The copper concentrations reported in kale plants grown on soil blended with industrial sludge in the current study of 49.5 mg/kg and 95.5 mg/kg for 50% IS and 80% IS respectively were all above the 5 mg/kg permissible limit set by WHO (Tomno et al 2020). In contrast to our results, Reis et al (2020) in their study observed copper concentrations in leaves of maize plants of up to 4.58 mg/kg which were much lower than those recorded in our study.…”

Green synthesis of copper nanoparticles extracted from guar seedling under Cu heavy-metal stress by Trichoderma harzianum and their bio-efficacy evaluation against Staphylococcus aureus and Escherichia coli

“…Bacteria such as Staphylococcus aureus and Escherichia coli, on the other hand, have been found in wastewater that used to irrigate the farmlands.Copper is an essential element for humans and plants when present in shortage amount, while in excess it exerts the detrimental effects (Kumar et al, 2021). Of course, it is worth mentioning that among heavy metals, copper (cu) is mainly found in urban sewage sludge (Reis et al, 2020). In this way, phytoremediation is a natural-based solution relying on the natural capability of plants to recover soil, sediment, water surface and groundwater contaminated with toxic metals, organic pollutants and radionuclides.…”