Ali 2024 — Microbial and heavy metal contamination in leeks, Iraq
Ali investigated both microbial (Escherichia coli, Klebsiella) and heavy metal (Zn, Cu, Pb, Ni) contamination in leeks collected from three agricultural stations in the Thi-Qar governorate of southern Iraq, across winter and summer seasons. One hundred leek samples were collected from farms, home gardens, markets, and vegetable vendors in and around Nasiriyah city. The study reports soil and plant tissue concentrations separately and documents a seasonal pattern (higher concentrations in summer) and a spatial gradient (higher contamination in district areas near pollution sources than in city center areas).
This is a conference proceedings paper (Seminar Nasional & Call Paper, Universitas Muhammadiyah Sidoarjo, Vol. 7 2024), which warrants caution regarding peer review rigor. The paper is open-access (CC BY). It is classified B-tier as conference proceedings with primary occurrence data rather than A-tier peer-reviewed journal.
Key numbers
Soil (µg/g dry weight):
- Winter season: Ni = 94.99, Cu = 44.82, Pb = 20.68 µg/g
- Summer season: Ni = 101.03, Cu = 62.10, Pb = 21.25 µg/g
- Highest contamination at Station 2 (near thermal electric station and traffic)
- Pb in soil within the permissible limit of 100 µg/g (WHO reference cited)
- Cu within WHO limits; Zn exceeds the permissible limit in both seasons
Leek plant tissue:
- Highest Zn concentration: 28.41 ppm during summer (from abstract; plant tissue data)
- District areas showed higher concentrations than city center areas across all metals and seasons
The paper presents data primarily in figures rather than tables, and the extracted file does not reproduce the figures. The soil concentrations above are from the text body. Exact leek plant tissue concentrations for Pb, Cu, and Ni are presented in figures (4–7 in the original) and cannot be precisely transcribed from the text alone; 28.41 ppm Zn (summer, plant tissue) is the only exact plant value in the abstract.
Methodological notes
Soil samples were digested with hydrochloric acid (15 mL per 1 g sample). Plant samples were washed, dried at room temperature, ground, sieved, then digested. The specific analytical instrument is referenced by citation [17] but not named in the text body. The absence of explicit LOD/LOQ values and the non-tabular presentation of metal data reduce this paper’s quantitative utility for the wiki’s evidence register.
The three-station design captures a spatial gradient from a known industrial point source (thermal electric station) to more distal agricultural areas, which provides useful context for supply-chain assessments of crops grown near point-source industrial pollution in lower-income MENA-region agricultural systems.
Relevance
The leek data are the most direct food occurrence contribution. Leeks are an Allium species with documented capacity to bioaccumulate Zn and Cu; the Zn value of 28.41 ppm (28,410 µg/kg) is consistent with the known Zn accumulation behavior of Allium species on metal-rich soils. However, because Zn, Cu, and Ni are essential metals with different toxicological profiles than Pb, Cd, iAs, and tHg, this paper’s direct relevance to the HMT&C analyte set is limited to lead (Pb) in leeks grown near industrial point sources in Iraq.
The seasonal and spatial patterns — higher metals in summer, higher near pollution sources — are consistent with findings from other MENA-region vegetable contamination studies and support the geographic variance framing on ingredient pages.
Limitations
Conference proceedings, B-tier. No DOI. Primary data presented in figures not recoverable from text extraction. Analytical method not fully specified. The Allium species studied (leek) is a minor crop in the HMT&C product scope. Iraq-specific findings have limited direct extrapolation to US/EU market supply chains.
Implications
Ingredients: marginal contribution to leafy-vegetables for the MENA-region geographic context and seasonal variance narrative. The spatial gradient near industrial point sources is a supply-chain screening argument.
Supply chain: supports the soil proximity-to-pollution-source framing on soil.