Effects of types of treatments of lead and cadmium on soil bioavailability: A potential human risk

Abstract

The effect of single and mixed treatments of Lead (Pb) and Cadmium (Cb) on soil bioavailability and
uptake by Brassica napus was investigated in green house using soil from Golden Ridge Estate and
wastewater from Pakamisa Sewage Treatment Plant, Gweru, Zimbabwe. Pb and Cd had significant
effects on metal soil bioavailability and yield in single treatments. Soil bioavailable Pb in mixed
treatments significantly correlated positively with uptake by B. napus. Yield was significantly correlated
negatively with soil bioavailable Pb and Cd as well as metal uptake. Soil bioavailable Pb accounted for
49.2% (single treatment) and 6.1 % (mixed treatment) of the variation in B. napus yield. Pb uptake
accounted for 4.63% (single treatments) and 88.77% (mixed treatments) of the variation in yield. Cd
accounted for 0.38% (single treatment) and 7.98% (mixed treatments) of the variation in yield. Findings
of this study indicate that B. napus grown in Golden Ridge Estate soil and irrigated with wastewater
from Pakamisa Sewage Treatment Plant accumulates Pb and Cd to above recommended maximum
limits for human consumption and is not fit for human consumption.