Assessment of Potentially Toxic Elements in Four Melon Fruit Varieties Grown in the Ganges and Yamuna River Basin

Overview

This study assessed eight potentially toxic elements (PTEs: Cd, Cr, Cu, Pb, As, Fe, Mn, Zn) in four melon varieties — two watermelons (Citrullus lanatus var. Arka Shyama and Crimson Sweet) and two muskmelons (Cucumis melo var. Cantaloupe and Kajri) — grown at 10 riverbank sites in the Ganges-Yamuna Basin of Northern India in summer 2024. Concentrations were measured in dry-weight edible pulp by ICP-OES after diacid digestion. Cd, Pb, and As levels in several samples exceeded WHO/FAO permissible limits on a dry-weight basis. Health risk indices (HRI, DIM, THQ) remained below 1 across all four varieties, with HRI for Cd, Cr, Pb, and Fe approaching 0.5 in watermelon and muskmelon varieties.

Key numbers

All concentrations in mg/kg dry weight (DW). Means ± SD across 10 sampling sites; each composite sample (5 fruits per site) analyzed three times.

Watermelon — Arka Shyama (Table 1):

Watermelon — Crimson Sweet (Table 1):

Muskmelon — Cantaloupe (Table 2):

Muskmelon — Kajri (Table 2):

Regulatory comparison (paper-internal, Section 3.1, p. 7): authors note that Cd in certain samples surpassed the 0.05 mg/kg threshold (WHO/FAO MPL for fruit; the paper cites the FAO/WHO Codex Committee on Contaminants in Foods, reference [40]) and that Pb concentrations approached 0.11 mg/kg at site L10. Several As values also exceed the 0.05 mg/kg level. Comparisons in the paper are stated on a dry-weight basis; the WHO/FAO MPL is normally applied to fresh weight, so direct comparability is limited (see Verification notes).

Health risk indices (Table 3):

DIM (mg/kg/day):

HRI (dimensionless):

THQ values were ≤0.0007 across all PTEs and varieties (Table 3). PCA reduced the dataset to two principal components capturing 95.65% (Arka Shyama: PC1 77.25 + PC2 18.40), 96.22% (Crimson Sweet: 87.53 + 8.69), 98.73% (Cantaloupe: 87.30 + 11.43), and 98.02% (Kajri: 93.74 + 4.28) of variance. Fe and Zn showed the most dominant distributions on L3 and L6 sites per the Arka Shyama PCA biplot (Figure 3b,d). HCA cluster-similarity pairs reported by the paper (Section 3.2): L2–L3 and L5–L7 for Arka Shyama; L3–L8 and L4–L5 for Crimson Sweet; L2–L9 and L7–L10 for Cantaloupe; L5–L9 and L4–L7 for Kajri. Per Section 3.1, Pb peaks at 0.11 mg/kg at site L10 (Crimson Sweet) and several samples exceed the WHO/FAO Cd MPL of 0.05 mg/kg DW.

Methods (brief)

ICP-OES (Perkin Elmer 7300 DV, Boston, MA, USA), p. 4 (Section 2.2). Edible pulp separated from ripened fruit, oven-dried at 60 °C to constant weight, and ground to fine powder. Digestion: 2 g dry powder + 20 mL HNO3/HClO4 (3:1, diacid mixture per USEPA Method 3050B), self-digested overnight (12 h), then heated on a hot plate at 150 °C for 1 h in a closed system with reflux condenser. Final volume adjusted to 50 mL with 3% HNO3 and filtered through Whatman No. 41 filter paper. Validation against certified reference material BCR679 (Merck, Mumbai, India) and standard reference materials (1000 mg/L stock, Merck, Mumbai, India). Statistics: PCA and HCA performed in OriginPro 2023 (OriginLab, Northampton, MA, USA); risk indices computed in Microsoft Excel 365.

Risk-index formulas (Section 2.3, p. 5): HRI = DIM/RfD; DIM = SS × HMc/Bw, with SS = 300 g dried weight/day, HMc = PTE concentration (mg/kg), Bw = 70 kg adult; THQ = 10⁻³ × (Ef × Ed × Ir × HMc/Bw × Cp × RfD), with Ef = 365 days, Ed = 365 days, Ir = 0.30 kg/day, Cp = 25,550 days, and RfDs in mg/kg/day (Cd 1.0×10⁻³, Cr 5.0×10⁻³, Cu 4.0×10⁻², Pb 4.0×10⁻⁴, As 3.0×10⁻⁴, Fe 7.0×10⁻¹, Mn 1.4×10⁻², Zn 3.0×10⁻¹).

Note: As reported as total arsenic (tAs); the paper does not speciate inorganic vs organic arsenic. Cr reported as total Cr; no Cr-VI speciation. LOD/LOQ values are not reported. Composite sampling structure (5 fruits pooled per site, 10 sites, 4 varieties) means per-fruit variability is not separable from per-site variability.

Implications

Certification: Contributes occurrence data for fresh melon (watermelon and muskmelon) grown under riverbank cultivation in Northern India; Cd, Pb, and As exceedances are reported on a dry-weight basis, with Pb peaking at 0.11 mg/kg DW at site L10. Wet-weight equivalents (assuming ~88% moisture in melon pulp) are roughly an order of magnitude lower than DW figures, which constrains direct comparison to fresh-fruit regulatory limits typically expressed on a wet-weight basis.

Courses: Strong case study for riverbank cultivation as a contamination pathway — sewage discharge, irrigation with contaminated surface water, and localized soil pollution all drive PTE accumulation in summer fruits. PCA and HCA methodology is well documented and reproducible for site-clustering exercises.

App: Origin-specific signal for elevated Cd, Pb, and As in melon fruit (watermelon and muskmelon) when declared origin is the Ganges-Yamuna agricultural basin of Northern India (Saharanpur/Haridwar districts).

Verification notes

Page enhanced 2026-05-19 from a prior revision dated 2026-05-14. Corrections applied against the source PDF (DOI 10.3390/horticulturae11020216):

• metals: previously listed Al (aluminum); the paper does not measure aluminum (PTE set is Cd, Cr, Cu, Pb, As, Fe, Mn, Zn per Section 2.2). Corrected to [Cd, Cr, Cu, Pb, tAs, Fe, Mn, Zn].
• ingredients: previously declared [[ingredients/muskmelon]], which is not a slug in the current taxonomy snapshot. Replaced with the umbrella [[ingredients/melon]] plus the existing [[ingredients/watermelon]] and [[ingredients/cantaloupe]] (cantaloupe is the named muskmelon variety in the study; Kajri is also a muskmelon cultivar but has no dedicated slug).
• raw_handle: previously the generic literal manual-fetch-kimi; corrected to the per-paper handle MFK_assessment-of-potentially-toxic-elements-in-four-m.
• raw_path: filename was truncated to ...Four Melon Fruit Vari.pdf; corrected to the actual filename on disk.
• matrices: previously included watermelon, muskmelon, and dry-weight, which are commodity names and a reporting basis respectively rather than matrix descriptors. Reduced to [fresh-fruit, melon-pulp, fruit].
• license: upgraded from CC BY to CC BY 4.0 per the paper’s copyright page.
• Tables for Crimson Sweet, Cantaloupe, and Kajri were previously abbreviated to selected metals; expanded to all eight PTEs to match Table 1 and Table 2 in the source.
• DIM and HRI matrices added from Table 3 (Section 3.3) — previously only narrative summaries were present.
• sample_population expanded to capture the L1–L4 (Yamuna), L5–L8 (Hindon/Solani tributaries), L9–L10 (Ganges) site partitioning (Section 2.1).
• Regulatory comparison clarified: the paper compares dry-weight concentrations to a WHO/FAO MPL normally applied on fresh weight, which limits direct interpretability; this caveat was added rather than removed because the paper itself makes the comparison.
• Legacy ## Wiki pages updated on ingest section removed per the current Part 6 source-page template.

Audit subagent (2026-05-19) findings — verified independently against the PDF and applied:

• ❌ Kajri As CV%: subagent flagged wiki value 11.84 as a column-shift duplicate of the Fe CV; Table 2 Kajri CV row reads 41.47/21.18/7.04/38.84/53.84/11.84/16.03/21.46 (Cd/Cr/Cu/Pb/As/Fe/Mn/Zn). Verified; corrected As CV to 53.84.
• ❌ Kajri As range: subagent flagged wiki value 0.01–0.07 as understating the minimum; Table 2 Kajri As column L1=0.02, no value below 0.02. Verified; corrected to 0.02–0.07.
• ⚠️ Kajri PCA variance sum: subagent flagged wiki “97.99%” as arithmetic drift; PC1=93.74 + PC2=4.28 = 98.02. Verified; corrected to 98.02 and added per-component variances for all four varieties.
• ⚠️ HCA hotspot attribution: subagent flagged that the wiki sentence “L3 and L6 … and L4 … as hotspots for elevated Cd, Pb, and As” is not in the source. Section 3.2 actually names Fe/Zn (not Cd/Pb/As) as dominant on L3/L6 in the Arka Shyama biplot, and identifies cluster-similarity pairs not “hotspots.” Verified; rewrote the sentence to track what Section 3.2 actually reports (similarity pairs L2–L3/L5–L7 for Arka Shyama, L3–L8/L4–L5 for Crimson Sweet, L2–L9/L7–L10 for Cantaloupe, L5–L9/L4–L7 for Kajri) and moved the regulatory-exceedance summary up from the prior hotspot sentence to a faithful restatement of Section 3.1.
• ⚠️ Wet-weight conversion in Implications/Certification: subagent flagged as borderline Part 2 (wiki-side arithmetic on top of a source-internal regulatory claim). Rejected as a correction: the conversion is framed as a comparability caveat (“constrains direct comparison”), not as a threshold proposal, and is necessary to honestly report the paper’s own DW-vs-WW MPL comparison. Leaving in place.
• ⚠️ matrices: melon-pulp not flagged as a new-vocabulary proposal: noted here. Matrices vocabulary per docs/gpt-collaboration/system-prompt.md is open (“Add a new term only if none of these fits”); melon-pulp is unambiguous and consistent with naming conventions like fish-muscle, cocoa-powder, egg-yolk already in use across the corpus. No correction required.
• Checks 2, 3, 4 returned ✅. Verdict was REVISE on the basis of the four findings above; after applying the three real corrections and rewriting the hotspot sentence, the page should clear a re-audit on Checks 1 and 5.

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and 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.