Accumulation of Heavy Metal Mercury (Hg) in Anadara Granosa and its Relationship with Water Physicochemical Parameters in Kayeli Bay, Buru Island

Abstract

Kayeli Bay, located in Buru Island, Maluku, Indonesia, is subject to mercury (Hg) contamination originating from illegal artisanal gold mining activities at Gunung Botak. Mining effluents are transported via the Waelata and Anahoni Rivers and deposited in bay sediments, creating a significant risk of Hg bioaccumulation in benthic organisms. This study aimed to quantify Hg concentrations in blood cockle Anadara granosa collected from three stations at different distances from the pollution source and also to determine the relationship between water physicochemical parameters (pH, temperature, salinity, and dissolved oxygen) and Hg accumulation levels. Samples were collected during February–March 2025. Mercury analysis was performed using a Mercury Analyzer (Analytic Jena Control AA). The results showed Hg concentrations of 0.41703 mg/kg (Station 1), 0.02539 mg/kg (Station 2), and 0.09531 mg/kg (Station 3). The highest concentration was found at the station closest to the river mouth, characterized by muddy substrate and weak currents. Measured physicochemical parameters included pH (6.4–7.0), temperature (29–38 °C), salinity (27.5–33.7 ‰), and dissolved oxygen (3.2–4.8 mg/L). Correlation analysis revealed that changes in pH, temperature, salinity, and dissolved oxygen played a very significant role in regulating the solubility, mobility, and bioavailability of Hg. Decreased pH and salinity, along with increased temperature and low dissolved oxygen levels, significantly enhanced the absorption and accumulation of Hg in tissues. Generally, Hg levels were below the national threshold (SNI 1.0 mg/kg), as well as the USA-FDA and Australian standards. However, levels at Station 1 exceeded the stricter limits set by Japan and Canada (0.3–0.4 mg/kg). Anadara granosa proved to be an effective bioindicator of heavy metal pollution, highly sensitive to changes in environmental quality.