Souri et al. 2019 - Growth-stage heavy metals in garden cress and sweet basil

Souri et al. measured heavy metals in garden cress and sweet basil grown in wastewater-irrigated fields south of Tehran, then compared young and mature garden-cress plants in a hydroponic Pb/Cd exposure experiment. The field results are directly routeable for leafy vegetables and fresh herbs because edible leaf tissue concentrations are reported in mg kg-1 dry weight. Garden cress leaves generally had higher Cd, Pb, tAs, Ni, Cr, Zn, Cu, and Mn than sweet basil leaves, and the hydroponic experiment showed higher Cd and Pb accumulation in young garden-cress shoots than mature shoots under several exposure levels.

Key numbers

• Field soil from the sampled farms contained Cd 12.2 mg kg-1, Pb 292 mg kg-1, As 7.4 mg kg-1, Cr 19.5 mg kg-1, Ni 16.8 mg kg-1, Zn 84.6 mg kg-1, Cu 22.7 mg kg-1, Co 12.1 mg kg-1, and Mn 46.4 mg kg-1 in loamy topsoil with pH 7.4 and EC 12.1 dS m-1 (Table 1).
• Garden cress edible leaves, mature plants (mg kg-1 dry weight, Table 2): Cd 4.02, Pb 39.0, Ni 6.4, As 1.9, Cr 12.7, Co 1.14, Zn 46.7, Cu 19.6, Mn 79.7.
• Garden cress edible leaves, seedlings (mg kg-1 dry weight, Table 2): Cd 4.43, Pb 40.4, Ni 5.8, As 2.4, Cr 12.0, Co 1.37, Zn 66.2, Cu 20.5, Mn 79.5.
• Sweet basil edible leaves, mature plants (mg kg-1 dry weight, Table 2): Cd 1.66, Pb 17.3, Ni 1.9, As 0.73, Cr 5.3, Co 0.48, Zn 39.7, Cu 13.3, Mn 48.4.
• Sweet basil edible leaves, seedlings (mg kg-1 dry weight, Table 2): Cd 0.90, Pb 11.7, Ni 2.2, As 0.62, Cr 4.2, Co 0.47, Zn 41.5, Cu 16.8, Mn 52.6.
• Table 2 prints the post-Zn copper column with a repeated “Co” header; the methods and results identify Cu as a measured analyte, so the post-Zn values are recorded here as Cu and the earlier Co column is retained as cobalt.
• In the hydroponic garden-cress Pb experiment, shoot Pb at 5 mg L-1 nutrient-solution Pb was 16.3 +/- 3.06 mg kg-1 DW in young plants and 10.8 +/- 1.9 mg kg-1 DW in mature plants; at 10 mg L-1 nutrient-solution Pb, shoot Pb was 27.8 +/- 3.12 mg kg-1 DW in young plants and 17.9 +/- 2.6 mg kg-1 DW in mature plants (Table 3).
• In the hydroponic garden-cress Cd experiment, shoot Cd at 5 mg L-1 nutrient-solution Cd was 6.25 +/- 0.90 mg kg-1 DW in young plants and 4.55 +/- 0.68 mg kg-1 DW in mature plants; at 10 mg L-1 nutrient-solution Cd, shoot Cd was 11.25 +/- 1.4 mg kg-1 DW in young plants and 5.78 +/- 0.96 mg kg-1 DW in mature plants (Table 4).
• The source-cited maximum allowable concentrations for leafy-vegetable tissues were Cd 2, Pb 5, As 4.3, Ni 15, Cr 5, Co 5, Zn 150, Cu 50, and Mn 150 mg kg-1 DW (Table 5).

Methods (brief)

The field study sampled garden cress in spring 2011 and sweet basil in summer 2011 from five nearby farms in Shahre Rey, south of Tehran, Iran. Each field sample consisted of three plants, with five samples used as replications. Young plants were 2-3 weeks old; mature garden cress and sweet basil plants were 7-8 weeks old. Leaves and roots were separated, washed, dried at 60 deg C for 48 hours, ground, ashed at 550 deg C for 6 hours, digested with HNO3 and HCl, filtered, and analyzed by atomic absorption spectrophotometry for Pb, Cd, Cr, Ni, As, Co, Cu, Mn, and Zn. Concentrations are reported as mg kg-1 dry weight.

The hydroponic experiment used 2-week-old and 6-week-old garden cress in sand culture with Hoagland nutrient solution containing 0, 5, or 10 mg L-1 Pb or Cd for 5 days. The design was completely randomized with four replications, five plants per pot, and Duncan’s multiple range test at p < 0.05.

Implications

Certification: The source contributes dry-weight occurrence values for leafy vegetables and fresh herbs grown in a high-exposure wastewater-irrigation setting. It should not be pooled silently with wet-weight retail vegetable studies without basis conversion.

Courses: The paper is useful for teaching why growth stage, tissue type, irrigation source, and basis matter for interpreting vegetable metal concentrations.

App: The source can support region-flagged, high-exposure context for leafy vegetables and fresh herbs from wastewater-irrigated fields in Iran, with explicit labels for dry-weight basis and total arsenic/total chromium.

Wiki pages this source may touch

• leafy-vegetables
• fresh-herbs
• leafy-vegetables-other
• non-root-vegetables
• cadmium
• lead
• arsenic-total
• chromium
• cobalt
• copper
• manganese
• nickel
• zinc

Verification notes

The auto-fetched filename describes formula cadmium, but the actual PDF is a leafy-vegetable paper; this page follows the PDF content and routes to leafy vegetables/fresh herbs, not infant formula.

Arsenic is treated as total arsenic because the source reports As without inorganic-arsenic speciation. Chromium is total chromium, not Cr-VI.

Table 2 appears to print the second copper column as “Co”; the methods and results text state that Cu was measured and discuss Cu leaf values. This page treats the second post-Zn column in Table 2 as Cu and records cobalt from the earlier Co column.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.