Asni & Najamuddin 2020 — Pb in Kappaphycus alvarezii Seaweed, Bantaeng Waters, Indonesia
This study measured lead (Pb) concentrations in cultivated red seaweed (Kappaphycus alvarezii) and surrounding water at three main sampling stations and three sub-stations in Bantaeng Waters, South Sulawesi, Indonesia, comparing rainy and dry season values. Pb concentrations in seaweed tissue exceeded Indonesia’s food safety threshold of 2.0 ppm at multiple stations in both seasons, with dry-season values substantially higher than rainy-season values. Stations nearer the coast showed higher Pb than offshore stations, consistent with terrestrial runoff, aquaculture effluent, and boat traffic as local contamination sources. The paper raises food safety concerns for K. alvarezii cultivation in Indonesian coastal waters where anthropogenic Pb inputs are elevated.
Key numbers
Pb in seaweed (Kappaphycus alvarezii) tissue, units mg/kg (ppm) wet weight:
- Rainy season: range 4.64–7.00 ppm across stations
- Dry season: range 1.20–20.87 ppm across stations
- Indonesian food safety threshold (SNI): 2.0 ppm
- Exceedances: Rainy season — all measured stations exceeded 2.0 ppm; Dry season — range straddles the threshold (lowest 1.20 ppm below, highest 20.87 ppm far above)
- Dry-season maximum (20.87 ppm) is approximately 10× the food safety threshold and approximately 3× the rainy-season maximum (7.00 ppm)
- Coastal stations consistently showed higher Pb than offshore stations in both seasons
Pb in water, units mg/L:
- Rainy season: 0.25–0.98 mg/L across stations
- Dry season: 0.20–1.13 mg/L across stations
- For context, WHO drinking water guideline for Pb is 0.01 mg/L; the measured water values exceed this by 20–100× in both seasons, indicating a heavily contaminated coastal environment
Seasonal pattern: Dry-season Pb is consistently higher than rainy-season Pb in both water and seaweed tissue. The authors attribute this to reduced dilution (lower river discharge) and concentration effects during dry periods, with the caveat that boat traffic and aquaculture activity may also intensify during the dry season.
Methods (brief)
Field collection from 3 stations × 3 sub-stations in two seasons. Seaweed samples: thallus tissue, rinsed with distilled water, dried, acid digested; Pb measured by AAS. Water samples: collected at surface; acidified; AAS. Specific instrument model not stated in available text. No certified reference material or recovery data reported. Sample n per station/season not explicitly stated in abstract/results; estimated 2–3 replicates per sub-station. Indonesian food safety standard SNI used as the comparison threshold (2.0 ppm for seaweed).
Limitation: Conference proceedings paper; limited methodological detail reported; small sample size; no speciation (total Pb only); no statistical analysis of between-station differences reported in the available text excerpt.
Implications
Certification: Relevant to the HMT&C seaweed/sea vegetable ingredient category. Confirms that K. alvarezii (cottonii), one of the most commercially important cultivated seaweeds, can carry Pb concentrations far exceeding food safety thresholds when cultivation sites are located in contaminated Indonesian coastal waters. The 10-fold dry-season spike (up to 20.87 ppm) is a strong argument for seasonal and origin-specific lot testing of seaweed ingredients sourced from Southeast Asian aquaculture regions.
Courses: Illustrates site-specific contamination in mariculture and the importance of cultivation-site water quality monitoring. Seasonal variation (dry vs. rainy season) is a production-chain variable that brands and suppliers can screen with targeted sampling protocols.
App: Seaweed ingredient Pb contamination profile contribution: Indonesian-origin K. alvarezii is a high-risk signal for Pb; dry-season harvests are higher risk than rainy-season harvests. The app should flag seaweed/sea vegetable ingredients when the supply-chain origin includes Indonesian coastal aquaculture.