Heavy Metal Index
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Heavy metal accumulation in leafy vegetables grown in industrial areas under varying levels of pollution

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Overview

Naser and coauthors measured Pb, Cd, Ni, Co, and Cr in spinach (Spinacia oleracea), red amaranth (Amaranthus tricolor), and amaranth (Amaranthus oleraseus) grown across a three-tier pollution gradient in Gazipur, Bangladesh: two industrial sites irrigated with Turag river water (high pollution, Kalakoir) or pond/kennel water (medium pollution, Zorun, Konabari) and one non-industrial experimental field (low pollution, BARI). The source is routeable to spinach and to leafy-vegetables-other because leaf and whole-plant tables report explicit dry-weight concentrations by species and by pollution level. Industrial-area findings should be kept jurisdiction- and site-contextual.

Key numbers

  • Spinach leaves in high-pollution areas: Pb 5.97 +/- 0.30, Cd 1.02 +/- 0.15, Ni 31.9 +/- 3.38, Co 1.63 +/- 0.24, and Cr 5.70 +/- 0.36 ug/g dry weight.
  • Spinach leaves in medium-pollution areas: Pb 3.61 +/- 0.18, Cd 0.52 +/- 0.03, Ni 24.6 +/- 2.23, Co 1.41 +/- 0.17, and Cr 5.62 +/- 0.23 ug/g dry weight.
  • Spinach leaves in low-pollution areas: Pb 1.16 +/- 0.16, Cd 0.43 +/- 0.07, Ni 5.48 +/- 0.47, Co 0.47 +/- 0.09, and Cr 2.69 +/- 0.24 ug/g dry weight.
  • Whole-plant spinach values were Pb 5.07 +/- 0.79, Cd 1.14 +/- 0.31, Ni 33.2 +/- 11.2, Co 1.60 +/- 0.27, and Cr 6.09 +/- 0.85 ug/g dry weight in high-pollution areas.
  • Regulatory comparison: authors compare whole-plant means against the FAO/WHO-Codex Alimentarius (1984) safe limits cited in the paper as Pb 5, Cd 0.3, Ni 20, Co 50, and Cr 5 ug/g dry weight. Cd in spinach and amaranth exceeded the Cd limit even in the low-pollution (BARI) field; Pb, Ni, and Cr exceeded their respective limits in vegetables from the polluted areas; Co stayed below its limit across all sites.

Methods (brief)

Plant parts and corresponding soils were collected from two industrial areas (Kalakoir and Zorun, Konabari, Gazipur) and one non-industrial area (BARI experimental field) from 6-week-old plants. Roots, stem, and leaves were separated. Samples were oven-dried at 65 C for 72 to 96 h, ground in a ceramic-coated grinder, then digested with HNO3:HClO4 (5:1 volume) for 1.5 h at about 190 C. Concentrations were determined in triplicate by atomic absorption spectrophotometry (VARIAN AA2407 AAS) and reported in ug/g on a dry-matter basis. Statistical differences were judged by Tukey’s multiple comparisons in Excel Statistics 4.0 (Esumi Co. Ltd., Tokyo, Japan).

Implications

Certification: site-specific Bangladesh spinach evidence for Pb, Cd, Ni, Co, and Cr. Courses: strong example of plant-part and pollution-gradient separation. App: supports high-risk industrial-area sourcing context, not a general-market spinach value.

Update history

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