Siltation load contribution of nickel laterite mining on the coastal water quality of Hinadkaban Bay, Surigao Provinces, Philippines

Abstract

Satellite images of Hinadkaban Bay, in Surigao Provinces, Philippines have indicated quite extensive siltation. Apparently, hilltop mining operations and other anthropogenic activities have resulted to deposition of suspended solids into the stretch of Hinadkaban Bay. In this regard, a multidisciplinary team was dispensed to undertake study in line with determining the environmental conditions along Hinadkaban Bay. Coastal marine water samples and surface water samples were obtained in two separate occasions (March and October 2012) via grab sampling. It was found that soil erosion in the study area was exacerbated by mining operations, road constructions and other anthropogenic activities, with heavy siltation often observed in areas near causeways, stockyards or siltation ponds of mine companies. Mean total suspended solids data of 5.87 mg/L was obtained for samples collected during the dry season while as high as 1000 mg/L TSS was recorded during heavy runoff. Meanwhile, average concentration of total nickel in water samples ranged from 0.050 μg/mL during dry season to 0.25 μg/mL during wet season. On the other hand mean total chromium concentration ranged from 0.060 μg/mL (dry season) to 0.30 μg/mL (wet season). Results of this study shall contribute to the effort of protecting surface water resources and of optimizing their beneficial uses.