Accumulation of Heavy Metals in Wheat (Triticum aestivumL.) Seedlings Grown in Soils Amended with Electroplating Industrial Sludge

Abstract

A glasshouse study was undertaken to evaluate the effect of lime-treated (0, 0.5, and 1%) industrial sludge amendments (10 and 20%) on wheat (Triticum aestivum L.) seedling growth and heavy metal accumulation in soils as well as in wheat seedlings. Industrial sludge-amended soil samples were filled in earthen pots (2 kg pot −1 ) one week before planting and 7-day-old seedlings were transplanted in pots (3/pot) and were kept in a glasshouse. Diethylenetriamine pentaacetic acid (DTPA)-extractable metals and metals in seedlings increase with increasing doses of industrial sludge. Biomass and growth have been found to increase with increasing rates of sludge. It also enhanced heavy metal concentrations in wheat seedlings and followed the trend zinc (Zn) > lead (Pb) > copper (Cu) > cadmium (Cd). Lime enhanced the biomass and reduced the heavy metal concentrations in wheat seedlings. Although 20% treatments in both soils showed a significant enhancement in shoot length, metals like Pb reached beyond permissible limits.

Achilles heel of environmental risk from recycling of sludge to soil as amendment: A summary in recent ten years (2007–2016)

“…High concentrations of all of the heavy metals present in sludge have been found in wheat grains, and significant correlations were found between the amounts of exchangeable heavy metal in the soil and the grain (Jamali et al, 2009). Similar conclusions to those drawn in the studies mentioned above, that heavy metal concentrations in plant tissues rose as the sludge application rate increases were observed by Bai et al (2010) and Sharma et al (2010), and they found that the heavy metal concentrations in plant tissues did not generally exceed local or national limits for edible agricultural products. However, Cd may be an exception because its concentrations in edible tissues have often been close to or above safe limits.…”

“…Wu et al (2011) studied whether humic acid controlling heavy metal speciation, and they found that components like fulvic acid (a type of humic acid) had significant quenching effects on Cd, Cu and Pb, showing that humic acid derived from sludge plays an important role in heavy metal speciation, in other words, in causing heavy metals to be inactive and restricting their uptake by plant. Tapia et al (2010) attributed the capacity of sludge to immobilize Cd to high degree of humification of organic matter, indicat- Sharma et al (2010) ing that humic acid performs an important function in immobilizing heavy metals. Pedra et al (2008) also found higher binding affinities between humic acids and heavy metal ions in sludgeamended soils than control, which is biochemical evidence for the effects of sludge on heavy metal bioavailability.…”

Effect of the Long-Term Application of Sewage Sludge to A Calcareous Soil on Its Total and Bioavailable Content in Trace Elements, and Their Transfer to the Crop

“…Some of these risks are the possible transfer of genes encoding resistance to antibiotics [11], and the accumulation of persistent organic pollutants [4] or of trace metals (TM) in soil. Trace metals can accumulate in the surface layers [12,[15][16][17] and/or leach out of the agrosystem [18][19][20], causing environmental contamination [4,21], ecotoxicity problems [14,22,23] or becoming part of the trophic chain due to their translocation in crops [21,24].…”

“…Along with these strategies, long-term studies are of great importance, as they allow observing the actual evolution of TM in soil, and therefore, the assessment of their true risk of accumulation and possible transfer to food, in the particular conditions of each soil and crop [16,17,[32][33][34]. In this sense, the literature shows variable results, with some studies showing enrichments of TM in crops [16,33], and other studies reporting no accumulation [24,35]. This reflects the possible influence of edaphoclimatic conditions and SS composition on the consequences of their application, and highlights the need to consider these conditions in its study.…”

Effects of long‐term sewage sludge application to a calcareous soil structure

“…Organic wastes, such as sewage sludge (SS), are a resource that can be converted to fertilizer (Metcalf & Eddy, 2003; Singh & Agrawal, 2008). Long‐term studies are important to understand the impact of applying SS, as it presents several risks to the environment by the accumulation of trace metals (TM) (McBride, 2003; Sharma et al, 2010; Zaragüeta et al, 2021) and resistance to antibiotics (Urra et al, 2019). Amending soils with SS generally improve some soil properties, such as SOM and nutrient contents, soil porosity, bulk density, aggregate stability or available water holding capacity (Annabi et al, 2011; Roig et al, 2012; Singh & Agrawal, 2008; Skowrońska et al, 2020; Soria et al, 2021).…”