Díaz et al. 2012 - Chilean algae arsenic

Díaz et al. measured total arsenic and inorganic arsenic in 79 algae samples representing 14 economically important species from Chilean coastal zones. The paper reports species-level mean concentrations in mg kg-1 d.w. and identifies which species were used for direct consumption, carrageenan, agar agar, or alginates. Total arsenic and inorganic arsenic are reported as separate analytes and are kept separate below.

Key numbers

Table 2 reports total arsenic and inorganic arsenic in mg kg-1 d.w. as mean ± standard deviation; n is the number of samples for that species:

The paper summarizes the 14-species dataset as total arsenic spanning 3.0 to 68 mg kg-1 and inorganic arsenic spanning 0.15 to 1.06 mg kg-1 in the abstract, while Table 2 reports the Macrocystis piryfera inorganic arsenic mean as 1.70 ± 0.80 mg kg-1 d.w..

Table 4 compares group means in mg kg-1 d.w. (mean ± standard deviation, n = 10):

The paper reports that inorganic arsenic accounted for 0.8% to 13% of total arsenic among the 14 species, with most arsenic present as organic arsenic.

Methods (brief)

Samples were collected in 2003-2004 from Caldera, Coquimbo, Pichilemu, Talcahuano, Mehuín, and Punta Arenas. The direct-consumption species Ulva rigida, Durvillaea antarctica, and Porphyra columbina were collected randomly from local markets; the remaining species were provided by commercial companies. Total arsenic was measured by dry ashing mineralization and FI-HG-AAS on 0.25 g lyophilized or dried seaweed, with a detection limit of 0.026 µg/g dry weight and precision of 2%. Inorganic arsenic was measured by acid digestion and solvent extraction FI-HG-AAS on 0.5 g lyophilized or dried seaweed, with a detection limit of 0.013 µg/g dw, precision of 4%, As(III) recovery of 99%, and As(V) recovery of 96%. Triplicate analyses were performed for each sample, and the coefficient of variation was less than 10%.

Implications

This source is high-value Chilean seaweed occurrence evidence because it reports both total arsenic and inorganic arsenic for named edible and phytocolloid-producing algae. Direct-consumption species and industrial seaweed-feedstock species should not be collapsed into a single species-level row without preserving the economic-use labels, sample counts, dry-weight basis, and tAs/iAs distinction. The Table 2 and abstract/Table 3 inconsistency around the upper iAs value should remain visible to downstream extractors.

Wiki pages this source may touch

• seaweed-kelp-foods
• supplements-algae-seaweed-based
• seaweed
• arsenic-total
• arsenic-inorganic

Verification notes

• Identity checks before writing found no existing source page for DOI 10.1016/j.fct.2011.11.024, raw handle MFK_10-1016-j-fct-2011-11-024-1, or cite key diaz2012-chile-algae-arsenic; the existing Rose 2007 page mentions this DOI only as a distinct comparison source.
• All Key numbers were rechecked against /tmp/hmi-seaweed-005.txt, extracted with pdftotext -layout, and Table 2 was visually checked against a rendered PDF page because the abstract/Table 3 range conflicts with the Table 2 Macrocystis piryfera iAs mean.
• Speciation check: total arsenic is recorded as tAs and inorganic arsenic as iAs; no total arsenic value is promoted to inorganic arsenic.
• Units and basis are preserved as mg kg-1 d.w., %, µg/g dry weight, and µg/g dw; no conversions were performed.
• Evidence tier A reflects peer-reviewed primary occurrence data, exact species/economic-use labels, species sample counts, triplicate analyses, detection limits, recoveries, and CRM QA/QC for total arsenic.
• Brand firewall: no sampled brands are reported. Instrument and CRM names are retained only as scientific method details.

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.