Assessing Temporal Changes in Microplastic Contamination in the Water and Sediment of Pekalongan Coastal Waters (2023–2024)

Abstract

Pekalongan waters are significant for fisheries, particularly small pelagic fish, due to plankton abundance, aquatic fertility, and location along the coastal migration line. However, recent coastal development has led to increased small-scale industries, textile production, and eco-tourism, which in turn elevate the levels of microplastics and other pollutants entering the marine environment. These pollutants, including organic waste, heavy metals, and plastics, threaten local ecosystems, especially mangroves and marine life. There are four mouth rivers that flow to the open sea and one lagoon, named Banger, Loji, Sengkarang, and Mrican, as a river and the lagoon close to the mangrove park, which transports pollutants between land and sea. Between 2023 and 2024, in situ observations were conducted to analyze microplastics in water and sediment samples, examining shape, size, and color with a Motic SMZ-161 microscope and assessing polymer composition via ATR-FTIR. Results indicated a rise in microplastic concentration from 2023 to 2024, from 6924 particles/L of water and 5240 particles/kg of sediment in 2023 to 7521 particles/L and 5702 particles/kg in 2024. This increase highlights ongoing anthropogenic impacts and inadequate waste management practices in the region.