Shue et al. 2012 — Seasonal heavy-metal variation in six bivalve species, Ta-Peng Bay, Taiwan

This study measured Cu, Zn, Pb, Ni, Cr, and Cd concentrations in six bivalve mollusc species from Ta-Peng Bay lagoon in southwestern Taiwan across four seasons (December 2005 to September 2006). Ta-Peng Bay is a shallow productive coastal lagoon described as heavily polluted by effluent from fisheries, domestic sewage, and agricultural wastewater. Cu and Zn dominated by mass across all species and seasons; Cd was the lowest by mass. Pb, Ni, and Cr declined with season rank (winter → spring → summer → autumn) and were significantly higher in winter; Cu, Zn, and Cd showed no significant seasonal correlation. Cd accumulation differed significantly between species (ANOVA F = 10.166, p < 0.001), supporting the authors’ suggestion that bivalve molluscs may serve as a species-sensitive monitoring tool for Cd in coastal waters.

Key numbers

Units: µg/g dry weight (ppm dry weight) for all metal values. Moisture (%) reported per species-season is the wet-weight fraction lost on drying at 105 °C — see Methods.

Pb (µg/g dry weight) — full Table 1 extraction

Mean (min–max) per species per season:

Highest Pb observed: P. viridis (green mussel), winter, 2.81 µg/g dry weight, range 2.34–3.08. Lowest among winter means: P. undulata (0.28 µg/g). Winter values exceed spring/summer/autumn for every species except S. diphos in summer. Tukey HSD confirms winter Pb is significantly higher than each of the other three seasons (p < 0.001).

Cd (µg/g dry weight) — full Table 1 extraction

A. antiquata accumulates Cd substantially above all other species in winter and autumn (~3–10× the species mean), driving the highly significant between-species ANOVA result (F = 10.166, p < 0.001). Cd was the lowest metal by mass overall but its species-dependence is the most pronounced of any analyte in the study.

Ni (µg/g dry weight) — Table 1, winter values

K. hiantina 2.31 (1.75–3.14) · A. squamosa 5.73 (5.70–5.75) · P. viridis 3.46 (1.55–5.76) · A. antiquata 1.99 (1.14–2.68) · P. undulata 1.80 (1.72–1.88) · S. diphos 1.70 (0.95–2.31). Autumn Ni drops sharply across all species (0.22–0.38 µg/g), and Tukey HSD identifies autumn as significantly lower than every other season (p < 0.001). ANOVA across seasons: F = 14.966, p < 0.001.

Cr (µg/g dry weight) — Table 1, winter values

K. hiantina 1.04 (0.77–1.46) · A. squamosa 4.06 (3.52–4.60) · P. viridis 2.68 (1.87–4.06) · A. antiquata 1.01 (0.41–1.57) · P. undulata 1.04 (0.95–1.14) · S. diphos 1.72 (0.68–2.77). Cr is the only analyte where summer ran high in A. squamosa (5.24 µg/g, range 0.22–10.3 — note the very wide range). ANOVA across seasons: F = 6.679, p = 0.001; Tukey HSD: winter > autumn (p = 0.003), spring < winter (p = 0.031), summer > autumn (p = 0.006).

Cu (µg/g dry weight) — winter range across species

3.50 (A. antiquata) to 18.4 (S. diphos), winter. S. diphos showed the highest Cu of any species-season cell (30.2 µg/g, summer; max single sample 38.0). Cu has no significant seasonal correlation (Pearson with season = 0.034, n.s.) but very strong between-species ANOVA (F = 21.494, p < 0.001).

Zn (µg/g dry weight) — winter range across species

48.3 (A. antiquata) to 77.2 (K. hiantina), winter. Highest single species-season cell: P. viridis spring at 89.0 µg/g (range 71.4–112.7). Zn has weak seasonal trend (Pearson = 0.003, n.s.) and a marginal between-species ANOVA (F = 2.712, p = 0.027).

Pearson correlations (Table 2) — analyte versus season rank

Pb −0.592 (p < 0.01) · Ni −0.565 (p < 0.01) · Cr −0.276 (p < 0.05) · Cu 0.034 (n.s.) · Zn 0.003 (n.s.) · Cd 0.029 (n.s.). Between-analyte: Pb–Ni r = 0.385 (p < 0.01); Pb–Cr r = 0.247 (p < 0.05); Ni–Cr r = 0.445 (p < 0.01); Cd–Cu r = −0.310 (p < 0.01); Cd–Pb r = 0.290 (p < 0.05); Cd–organism r = −0.422 (p < 0.01).

Moisture content (% wet-tissue water lost on drying at 105 °C)

Ranges by species across the four seasons: K. hiantina 71.0–78.6 · A. squamosa 72.6–76.5 · P. viridis 72.7–81.1 · A. antiquata 69.5–74.2 · P. undulata 74.1–82.2 · S. diphos 75.5–82.1. For wet-weight conversion of any dry-weight value reported above, use the species-season moisture in Table 1; the dry-to-wet conversion factor is (1 − moisture_fraction). Example: P. viridis winter Pb 2.81 µg/g dry × (1 − 0.811) = ~0.53 µg/g wet (≈ 530 ppb wet).

Analytical instrument and statistics

Hitachi Z-5000 atomic absorption spectrophotometer, air-acetylene flame and graphite-furnace atomizer modes; calibration with five-point standard curves per analyte; each sample measured in triplicate. Statistical analysis: Pearson bivariate correlations between analyte concentrations and season/source/organism; one-way ANOVA across species and across seasons; Tukey HSD multiple-comparison test for season pairs. All statistics in SPSS 10.0; α = 0.05.

Methods (brief)

Field collection from Ta-Peng Bay lagoon at four sampling times (12/2005, 03/2006, 06/2006, 09/2006). Standard shell size selected for each species; specimens iced in transit and stored at −20 °C. Soft tissues (and mussel byssus, where present) dissected with a plastic knife, rinsed in distilled water, and oven-dried at 105 °C to constant weight on aluminium trays (not freeze-dried). Dried samples were ground to fine powder and homogenised in a mortar; approximately 1.0 ± 0.01 g dry tissue was weighed per analytical aliquot. Digestion: 10 mL concentrated HNO₃ (65%) overnight at room temperature, then 4 h at 95 °C, followed by addition of 2 mL 30% H₂O₂ and continued digestion at 95 °C until the solution cleared (nitric-peroxide digest, not nitric-perchloric). Filtered through 0.45 µm cellulose-nitrate membrane (Advantec MFS), diluted to 50 mL with deionised distilled water. Cu, Zn, Pb, Ni, Cr, and Cd measured by AAS (Hitachi Z-5000, Japan) using air-acetylene flame and graphite-furnace atomizer modes; triplicate measurement per sample. Results expressed as µg/g dry weight.

Limitations:

• Conference-proceedings venue (Advanced Materials Research / Trans Tech) implies lighter peer review than a primary analytical-chemistry journal.
• No certified reference material (CRM) recovery, no LOD/LOQ values, and no procedural blanks are reported in the paper as published.
• No Zeeman or other background-correction technique is named; the instrument is identified only as “Hitachi Z-5000” and the spectrometer mode is given. Earlier versions of this wiki page asserted “Zeeman background correction”; that detail is not in the source and has been removed.
• No speciation reported; Cr is total Cr (Cr-III + Cr-VI combined), and As/Hg were not measured.
• Small replicate count (n = 3 per species-season cell, total n = 72) — sub-cell ranges are wide for several species (e.g., A. antiquata winter Cd 0.30–3.00) and individual cell means should be read with that caveat.
• Paper-internal naming inconsistency: the Methods section names one species “Scapharca satowi” while the abstract, introduction, results text, and all four Table 1 columns label the same species “Anadara antiquata”. Scapharca and Anadara are taxonomically intertwined (Scapharca species have been reassigned to Anadara historically); this looks like an author oversight rather than a different species, but the inconsistency is in the published record.

Implications

Certification. Relevant to HMT&C product categories involving bivalve shellfish (clams, mussels, ark-shells, surf-clams). The winter peak for Pb / Ni / Cr in this Taiwanese lagoon and the species-specific Cd accumulation pattern (A. antiquata is the high-Cd species here) are evidence that annual spot-check testing of shellfish ingredients is structurally insufficient when both season and species drive concentration; lot-level testing with species + harvest-season metadata is the literature-supported posture. Wet-weight conversion is required before any literature value here can be compared to food-safety limits stated as fresh weight (EU 2023/915 Pb 0.30 mg/kg WW for bivalves; Codex Cd 2.0 mg/kg WW for bivalve molluscs). Example: P. viridis winter Pb 2.81 µg/g dry × (1 − 0.811 moisture) ≈ 0.53 mg/kg WW — i.e., exceeds the EU 2023/915 bivalve Pb maximum at the dry-weight cell mean. A. antiquata winter Cd 1.77 µg/g dry × (1 − 0.738) ≈ 0.46 mg/kg WW — well below the Codex 2.0 mg/kg WW Cd maximum, but the cell range extends to 3.00 µg/g dry (≈ 0.79 mg/kg WW).

Courses. Strong case study for the shellfish module: (a) species identity drives Cd contamination far more than season does; (b) season drives Pb / Ni / Cr far more than species does; (c) Cu and Zn are physiologically regulated essentials, not contamination signals, and should not be conflated with non-essential metals in food-safety framing. Useful for illustrating why “shellfish” is too coarse a category for risk assessment — the within-genus differences here (e.g., A. antiquata Cd vs P. viridis Cd) are larger than the differences between many other ingredient categories.

App. Bivalve shellfish ingredient contamination profile contribution (Taiwan, dry-weight basis with moisture provided per cell — conversion to wet weight requires the species-season moisture, not a generic factor). High species-by-season variance argues against a single point estimate for the “shellfish” ingredient class in the app; the app should at minimum surface that bivalve Pb is winter-loaded and that Cd is taxon-loaded.

Verification notes

Page was rebuilt from the PDF on 2026-05-18 to correct method-detail invented by an earlier ingest pass and to extract Tables 1, 2, 4, and 5 in full.

• Audit subagent (2026-05-18) flagged Cd–Pb correlation as p < 0.01; verified against Table 2 — the cell reads “0.290*” with a single asterisk, and the table footer defines * as p < 0.05 (and ** as p < 0.01). Corrected to p < 0.05.
• Audit subagent (2026-05-18) flagged Cr summer A. squamosa value of “5.24 µg/g, range 0.22–10.3” as wrong, claiming Table 1 reads 0.75 (0.34–1.08). Verified against Table 1 (06/2006 summer row, Cr line): the value 5.24 (0.2210.3) is in the A. squamosa column; 0.75 (0.341.08) is in the P. viridis column. The subagent misread the column. Wiki value retained.
• Earlier version stated tissues were “lyophilized (freeze-dried)“. The source says “Dried samples were dried at 105 ºC to keep a constant dry weight” (Methods, Sampling and Pretreatment paragraph) — i.e., oven-drying. Corrected.
• Earlier version stated the digestion was “HNO3/HClO4”. The source describes 10 mL HNO₃ + 2 mL 30% H₂O₂ (Methods, Analysis for Heavy Metals paragraph). Perchloric acid is not used. Corrected.
• Earlier version stated “Zeeman background correction” on the Hitachi Z-5000. The source identifies only “AAS, HITACHI, Z-5000, Japan” with “air-acetylene flame / Graphite Atomizer”. Zeeman is not in the source. Removed; the limitation now notes absence of stated background-correction technique.
• Earlier version asserted K. hiantina was “highest Pb among the six species in winter” at 1.75 µg/g. Table 1 clearly shows P. viridis at 2.81 µg/g is the highest winter Pb cell. Corrected; full Pb table extracted.
• Earlier version stated “data in paper tables (not extracted in full)” for several analytes. Full Tables 1, 2, 4, 5 are now extracted per the Cochrane-bar requirement that mandatory tables be read and transcribed.
• Earlier version compared Cd species-dependence to “Rajeshkumar et al. 2018 for oyster (Crassostrea gigas) vs. crucian carp in Taihu Lake”. That paper is not cited by Shue 2012 and the comparison was external editorial. Removed.
• Earlier version glossed S. diphos provenance as “from marine culture”. Source specifies the marine-culture zone at the estuary of Lin-Bian River; sample_population now records that.
• Earlier version used wet-weight conversion approximation “÷5” without grounding. Source reports species-season moisture in Table 1 (range 69.5–82.2%). Conversion guidance now uses the source’s own moisture figures.
• Paper-internal inconsistency between “Scapharca satowi” (Methods) and “Anadara antiquata” (abstract, results, tables) noted under Limitations.
• A broken outbound link to [[supply-chain/mariculture-taiwan]] was removed; no such page exists.

Wiki pages updated on ingest

• shellfish
• bivalve-molluscs
• molluscs
• lead
• cadmium
• nickel
• chromium
• copper
• zinc
• shellfish
• seafood

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.