Abstract:
Food contamination by heavy metals has been a major concern in recent years due to
their potential to accumulate in bio-systems via contaminated water, and soil. Fruits
are an important part of a healthy diet due to their nutritional values, which help
in preventing major diseases. As a result, any form of contamination by heavy metals is
of great concern. The main objective of this study was to determine the concentrations
of some selected heavy metals in irrigation water, soil, and fruit samples of (Orange,
and Pawpaw) collected from the Tibila Farm of the Boset District, Oromia regional
state, Ethiopia. The composite samples of soil, water, and fruits were collected
randomly from the Farm during the wet season. To decompose organic materials and
solubilize metals from the samples, optimal wet digestion techniques were used. The
validation was performed by spiking the samples with a standard solution of each metal
having a known concentration, and the percentage recovery values for all samples were
in the range of (81-110%) with a relative standard deviation of (0.24-14.3%). After wet
acid digestion, the collected samples were analyzed for Cd, Pb, Zn, Cr, Cu, Mn, Fe, Co,
and Ni, with flame atomic absorption spectrometry (FAAS). The MDL and LOQ values
recorded were greater than the IDL, indicating that the instrument used was sensitive.
The result of the study showed that the heavy metals concentration in the studied
samples was in the decreasing order of: Fe > Mn > Zn >Cu > Cr > Ni > Co; Fe > Cr
> Zn > Cu > Ni > Mn > Co; Zn >Cr > Fe > Mn > Cu > Ni > Co; Zn > Fe > Cr > Cu
> Co > Ni > Mn in the soil, water, orange and pawpaw samples, respectively. The
concentration levels of Mn, Zn, & Cu in the soil; Zn, Cr, Mn, Fe & Ni in orange; Zn,
Fe, Cr, & Ni in pawpaw; and Zn, Cr, Cu & Ni in the water sample exceeded the
permissible limit set by WHO/FAO. The result of one-way ANOVA revealed that there
was a significant difference between the samples (p < 0.005; 95% CL) for all metals in
the soil, water & fruits. According to the findings of this study, continuous heavy metal
inspection in farm products is required to avoid contamination and ensure human
safety
