Overview
This study characterises trace element concentrations in soils and rice grains from the Baixo Vouga Lagunar (BVL), a coastal lagoon agriculture zone in northern Portugal, with analytical focus on arsenic (total), lead, and uranium alongside copper. Five rice grain samples were analysed by ICP-MS: three annual harvests of white Carolino variety (2020, 2021, 2022), one wild-rice sample, and one brown-rice sample. All grain concentrations fell well below European Commission regulatory limits, though soil enrichment factors revealed legacy anthropogenic loading of arsenic (As), lead (Pb), and uranium (U) in the agricultural soils.
Key numbers
Rice grain concentrations (ICP-MS, µg/kg dry weight, n=5 samples; values extracted from Table 4 / results section):
| Analyte | Range across samples | Regulatory limit (EC) |
|---|---|---|
| total arsenic (tAs) | not individually tabulated per grain variety — reported as below EC limit (200 µg/kg for rice) | 200 µg/kg (white rice, EC 2023/465) |
| lead (Pb) | below EC limit | 200 µg/kg (rice, EC 2023/915) |
| uranium (U) | below EC limit | no harmonised EC food limit at time of publication |
Soil concentrations (mg/kg) showed As enrichment factors up to ~3× background in some paddy plots; Pb and U similarly elevated relative to geochemical background, attributed to historical industrial activity and agricultural inputs in the BVL catchment.
Methods (brief)
Analytical method: ICP-MS (total digestion of rice grain and soil samples). Speciation: total arsenic (tAs); no HPLC speciation performed — inorganic arsenic fraction not reported. Sample preparation: microwave acid digestion. LOD/LOQ: not explicitly stated for grain matrix. Quality control: certified reference materials used for soil; grain QC details limited.
Limitation: very small grain sample set (n=5); no statistical range across field plots. Results are indicative of this specific agroecosystem and should not be generalised to Portuguese or Carolino variety rice broadly.
Implications
Certification: tAs values are below EC limits but the paper does not report numeric grain concentrations explicitly; cannot extract ppb values for use in concentration distributions. Useful as geographic context for European paddy rice rather than as a Path A concentration dataset.
Courses: illustrates soil-to-grain transfer pathways and the role of flooded paddy conditions in As accumulation; useful for supply-chain module.
App: rice-grain tAs, Pb, U matrices confirmed present but no extractable numeric grain concentrations for contamination_profile update; status remains data-gap for numeric synthesis.
Microbiome: not applicable.
Related evidence
Update history
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