Baseline study on the levels of heavy metals in seawater and macroalgae near an abandoned mine in Manicani, Guiuan, Eastern Samar, Philippines.

Lateritic nickel ore stockpiles are still present in Manicani Island after mining activities were suspended in 2001. This study aimed to assess the water quality in the island by measuring the levels of Pb, Ni and Cu in seawater and Sargassum polycystum samples collected quarterly in 2018. The levels of the three heavy metals in seawater samples were 0.388 ±â€¯0.058-1.508 ±â€¯0.120 mg/L Pb, 0.457 ±â€¯0.003-0.531 ±â€¯0.005 mg/L Cu, and 0.122 ±â€¯0.008-0.628 ±â€¯0.281 mg/L Ni. All values are above the permissible limits recommended by DENR and USEPA. Ni (13.630 ±â€¯7.341-160.120 ±â€¯3.375 mg/kg) had the highest concentration in S. polycystum, significantly higher than Pb (