| dc.description.abstract | Pollution of the environment by heavy metals emanating from rapid economic growth and
improper waste and effluent disposal is a major concern. In this study, heavy metal
concentrations (Cd, Cu, Pb, Zn and Cr) in vegetables, soil and water in two urban streams in
Machakos municipality were analyzed. Physicochemical parameters; pH, temperature, total
dissolved solids (TDS) and electrical conductivity (EC) were also measured on-site. One-way
Analysis of variance (ANOVA) was used to test for the significant difference (p≤0.05) of heavy
metal concentrations in the vegetables, soil, and water across the different sampling sites. The
relationship between the heavy metals in the soil, water and vegetables was investigated using
Pearson correlation. Temperature (21.58 – 23.05 ºC), pH (7.5 – 8.45) and TDS (577.5 – 865.83
mg/L) mean values were found to be within WHO acceptable limits for surface water while EC
(864 – 1778.5 µS/cm) exceeded the set limits. Results showed that the mean concentrations
(mg/kg) of Cd (BDL – 0.0011), Cu (0.0034 – 0.0055), Pb (0.0012 – 0.007), Zn (0.0232 -
0.1351), and Cr (0.0036 - 0.0292) in water and Cd (0.0058 - 0.0534), Cu (10.39 – 27.5), Pb (4.23
- 8.35), Zn (20.1 – 28.8) and Cr (8.17 – 10.03) in soil were within WHO permissible limits.
Mean concentration values of (Zn (9.05 – 11.8), Pb (0.28 – 0.636), Cr (BDL – 1.002)) in spinach
exceeded WHO permissible limits while Cd (BDL – 0.1285) and Cu (3.07 – 14.5) were within
recommended levels. Cd (0.004 – 0.243), Cu (0.909 – 3.60) and Pb (BDL – 0.458) concentration
levels in kale were within WHO safe limits for human consumption while Zn (12.06 – 18.8) and
Cr (BDL – 1.62) exceeded WHO set limits. Presence of heavy metals (Zn, Pb, Cr) in the
vegetables signifies a health risk hazard from consumption of these vegetables. Continuous
monitoring of heavy metals in stream water, soil and vegetables is critical towards safeguarding
public health | en_US |
