Copper Determination from Calancan Bay Seawater: A Method Optimization and Ruggedness Analysis

For 16 years, Marcopper Mining used Calancan Bay in Sta. Cruz, Marinduque, as a dumping site for mine tailings. These waste materials, rich in heavy metals, pollute nearby rivers and coastal waters, threatening marine life and human health. This study aimed to measure copper [Cu] levels in Calancan Bay seawater, with method optimization and ruggedness tests conducted on simulated samples. The method optimization includes instrument and acid digestion parameters. After which, the optimized protocol was applied to field samples. Ten sampling sites were selected, with four trials conducted per site. Copper concentrations were measured using Atomic Absorption Spectrophotometry. Statistical analyses (p > 0.05) indicated that sites 1 and 2, with [Cu] values of 0.1949 ± 0.0007 mg/L and 0.1937 ± 0.0007 mg/L, respectively, were within the DENR threshold limit (DAO-2021-19). Site 3, located closest to the effluent discharge pipe, exceeded the threshold with a concentration of 0.2733 ± 0.0024 mg/L. All remaining sites were below the regulatory limit. These results highlight the localized elevation of copper levels near discharge points and underline the need for continued rehabilitation efforts to mitigate heavy metal contamination in Calancan Bay.