The Effect of Irrigation with Well Water from the Sana'a Basin, Near Various Pollution Sources, on Some Heavy metals in Soil and Radish Plants

Abstract

This study evaluated soil and plant contamination by heavy metals (Fe, Cu, Zn, Mn) in the Sana’a Basin,
Yemen, resulting from irrigation with well water located near three pollution sources: (A) the municipal
landfill in Al-Azraqain, (B) sewage effluents in Bani Al-Harith, and (C) stormwater runoff in Al-Rawdah.
Four wells were sampled per site, and a pot experiment using radish (Raphanus sativus L.) was conducted
during the spring season (February–April) to assess enrichment, transfer, and bioaccumulation factors.
Results revealed that Fe and Mn were most concentrated in wells near the landfill (A), likely due to
ferrous and metallic waste, while Cu was highest in Bani Al-Harith (B), possibly linked to coppercontaining materials and pipelines. Zn levels peaked in Al-Rawdah (C), attributed to stormwater transport
across agricultural soils treated with Zn-containing fertilizers and pesticides. Although none of the
detected concentrations exceeded permissible irrigation water limits, soil contents of Fe and Mn increased
substantially after cultivation (279% and 245% of initial values, respectively), whereas Cu and Zn rose by
32% and 59%.
Enrichment factor (EF) analysis indicated Cu accumulation in soils irrigated with water from all wells.
Pollution sources significantly influenced Mn concentrations in both shoots and roots, Fe in roots only,
and Zn variably between shoots and roots depending on the site. Radish exhibited effective Zn
accumulation in both shoots and roots under irrigation with water from site B, but only in roots under site
A, suggesting its potential as a bioindicator for Zn-contaminated soils.
Translocation factor (TF) results showed that radish efficiently absorbed and translocated Cu from roots to
shoots at site A, but not at sites B or C. Bioaccumulation factor (BAF) values in radish roots followed the
order Zn (1.18) > Cu (0.14) > Mn (0.13) > Fe (0.04). The findings highlight a potential human health risk
associated with heavy metal accumulation in edible plants and their entry into the food chain.