Seasonal variation in total heavy mineral concentration along a monsoon-influenced coast: a case study from Kalutara, Sri Lanka

The seasonal variations of heavy mineral concentrations in coastal sediments affect nearshore sediment dynamics, mineral resource potential, and depositional processes. This study investigates the influence of monsoonal wave dynamics on the heavy mineral distribution along the Kaluthara coast in southwest Sri Lanka, which is an active sedimentary environment shaped by the discharge of the Kalu river and is influenced by both Southwest (SW) and Northeast (NE) monsoons. Sediment samples were collected from 10 locations post-SW and post-NE monsoons from the beach face. Bromoform (SG = 2.89 g/cm3) was used for the separation of heavy minerals from the sediment samples. The results showed significantly higher Total Heavy Mineral concentrations during the post-NE monsoon season, in contrast to the post-SW monsoon season, which is associated with high-energy wave activity, possibly due to erosion and sediment reworking. This highlights the dynamic relationship between seasonal hydrodynamics and heavy mineral enrichment. This study contributes valuable insight to the temporal behavior of heavy mineral accumulation, which can be helpful in mine planning and exploration.