Heavy Metal Phytotoxicity to Radish (Raphanus sativus L.) in a Digested Sludge-amended Gangetic Alluvium

Abstract

A limiting factor in land application of sewage sludge is the resultant heavy metal accumulation in soils followed by biomagnification in the food chain, posing a potential hazard to animal and human health. In view of this fact, pot experiments were conducted to evaluate the effect of digested sludge application to soil on phytotoxicity of heavy metals such as Cd, Cr, Ni, and Pb to radish (Raphanus sativus L.) plants. Increasing sludge levels resulted in increased levels of DTPA-extractable heavy metals in the soil. Cadmium was the dominant metal extracted by DTPA followed by Ni, Pb, and Cr. The extractability of metals by DTPA tended to decrease from the first to the second crop. Dry matter yield of radish increased significantly as a function of increasing sludge treatments. Soil application of sludge raised the concentration of one or more heavy metals in plants. Shoots contained higher concentrations of Cd, Cr, and Ni than the roots of radish plants. Shoot concentrations of Cd, Cr, Ni, and Pb were within the tolerance levels of this crop at all rates of sludge application. Shoot as well as root concentration of Cd was above 0.5 mg kg −1 , considered toxic for human and animal consumption. The levels of DTPA-extractable Cd and Ni were less correlated while those of Cr and Pb were more correlated with their respective shoot and root contents. The results emphasize that accumulation of potentially toxic heavy metals in soil and their build-up in vegetable crops should not be ignored when sludge is applied as an amendment to land.

Potato absorption and phytoavailability of Cd, Ni, Cu, Zn and Pb in sierozem soils amended with municipal sludge compost

“…In this research, MSC promoted the potato uptake of heavy metals, which is similar to the results of Bozkurt et al (2010) and Bhat et al (2011). This might be attributed to the increased labile fraction proportion of heavy metals.…”

“…Chelating agents and dilute acids are usually used to assess the potential toxicity of heavy metals, and the heavy metals extracted by chelating agents and dilute acids could represent the long-term available metals in soils (McLaughlin et al, 2000a). The labile fraction proportion of heavy metals increased with increasing MSC percentage in amended sierozem soils (Bhat et al, 2011;Delgado et al, 2012;Arvas et al, 2013). Zubillaga et al (2012) reported that the labile fraction proportion of heavy metals in soil-sludge mixtures decreased with increasing soil OM content.…”

Heavy metal accumulation in various tissues of radish (Raphanus sativus) grown under different ratios of organic amendments

“…5 and 6). Similar results reported for Cr in radish by Bhat et al [2011]. The distribution of metals in different plant tissues depends on their form, water transport and plant species [Ouzounidou et al 1995] therefore, it is difficult to export a general conclusion.…”

Environmental zoning based on the distribution of potentially toxic elements, risk contamination indices, and bioindicators in three areas affected by gold mining in Antioquia, Colombia

“…In this study, biomonitoring using radishes and PVI index were proposed. Previous research has shown that radishes has exhibited significant responses to changes in contamination levels associated with potential toxic elements and other pollutants in complex matrices (Tiwari et al, 2013;Acosta-Luque et al, 2023;López et al, 2023;Serrano et al, 2023;Bhat et al, 2011).…”