Morita and Shibata 1990 - chemical forms of arsenic in marine macroalgae

Morita and Shibata reviewed water-soluble and lipid-soluble arsenic compounds in marine macroalgae and added a HPLC/ICP/MS species-map table for Japanese algae. The paper is useful speciation context for seaweed because it separates total arsenic, lipid-phase arsenic, water-phase arsenic, arsenosugars, arsenate, and unidentified arsenicals. It should not be read as a modern market-occurrence survey, and the symbol-coded species map should not be converted into exact inorganic-arsenic concentrations.

Key numbers

The paper reports algae arsenic concentrations in µg/g dry in Table 2 unless a row is explicitly marked wet base; no unit conversion was performed. Table 2 covers 38 marine algae and one higher plant comparator, with total arsenic, lipid-phase arsenic, water-phase arsenic, and symbol-coded arsenic species.

Table 2 numeric ranges by phylum, excluding the rows footnoted as wet base:

Wet-base purification-study rows in Table 2:

The Table 2 species symbols are semi-quantitative: the paper defines free marks as 0.1-1 µg/g As (dry), 1-10 µg/g As, and more than 10 µg/g As; open circles mark compounds identified by purification studies, and a double circle marks the most abundant species. Those symbols are retained as qualitative speciation context rather than exact concentration values.

Other source-stated figures and findings:

• The introduction states that brown algae contain arsenic at “several tens of ppm” on a dry-weight basis, while green and red algae contain “several ppm” on a dry-weight basis.
• The paper estimates daily arsenic intake through marine algae ingestion in the average Japanese diet at about 100 µg/day.
• The review cites Lunde’s finding that 97% of arsenic in Laminaria hyperborea was organic arsenic and Sanders’s examination of 56 algae species, where arsenic was organic at 53% in Chlorophyceae, 78% in Phaeophyceae, and 57% in Rhodophyceae.
• For Hizikia fusiforme, the paper states that the major methanol-extract arsenical was inorganic arsenate (50%) together with compound As-IV. It also states that inorganic arsenic in H. fusiforme was found only in the surface layer, while arsenic-ribofuranosides were distributed more evenly in tissue.
• For Sphaerotrichia divaricata, the text states a typical arsenic concentration of about 2 ppm on a wet-weight basis; about 25% of methanol-extracted arsenic was lipid soluble and the remainder water soluble.
• For Undaria pinnatifida, the lipid-soluble arsenic was identified as a diacylated derivative of compound As-II, and the text states that 25% of arsenic was in lipid-soluble form.

Methods (brief)

This is a peer-reviewed review article with an embedded HPLC/ICP/MS characterization table. Table 1 lists marine algae collected from Choshi, Chiba Prefecture on May 26, 1987, Hiraiso, Nakaminato, Ibaraki Prefecture on June 17, 1987, and Inamuragasaki, Kamakura, Kanagawa Prefecture on July 11, 1987; species identifications were performed by named phycologists. The review also summarizes prior purification work using methanol extraction, Sephadex/DEAE/CM chromatography, HPLC-ICP methods, NMR, GC/MS, and radiolabel assimilation studies. The PDF itself does not print a DOI; the DOI in frontmatter was verified from external bibliographic metadata for the same title, authors, journal, volume, pages, and year.

Implications

This source is a historical speciation anchor for seaweed arsenic. It supports the wiki rule that total arsenic in seaweed cannot be treated as inorganic arsenic and that organic arsenosugars, lipid-soluble arsenicals, arsenate, DMA, and unidentified species must remain separate. For occurrence pooling, downstream work should prefer the primary papers behind the review and use this page as context unless a later extraction pass explicitly models Table 2’s semi-quantitative species symbols.

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 10.1002/aoc.590040303, raw handle MFK_morita1990, title text, or cite key morita1990-marine-macroalgae-arsenic-forms.
• Text was extracted to /tmp/hmi-seaweed-050.txt with pdftotext -layout; the abstract, methods narrative, and most prose were readable. Table 2 was visually checked from rendered page images because the text extraction mangled the wide symbol-coded table.
• All Key numbers were checked against /tmp/hmi-seaweed-050.txt and the rendered Table 2 page images, especially phylum total-As ranges, wet-base footnotes, the 100 µg/day intake estimate, the 50% Hizikia fusiforme arsenate statement, and the Table 2 symbol legend.
• Units and bases are preserved as µg/g dry, µg/g As, wet base, ppm, and µg/day; no unit conversion was performed.
• Speciation check: total As, inorganic arsenate, lipid-soluble arsenic, water-soluble arsenic, arsenosugars/arsenic-containing ribofuranosides, DMA, As-I through As-VI, and unidentified species are not collapsed into a single arsenic species.
• Brand firewall: no consumer brands are named.
• Missing-slug check: no missing product or ingredient slug blockers. Exact algae species remain in Key numbers/prose while frontmatter uses broad seaweed/kelp food and algae/seaweed supplement routing.

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.