Distribution and characteristics of microplastics in seawater, sediment, and crude salt from Madura Island, the largest solar salt production island in Indonesia

The presence of microplastic (MPs) pollutants in the environment, particularly in terrestrial and aquatic ecosystems, has aroused concern worldwide. This study investigates the distribution and characteristics of MPs in seawater, sediment, and crude salt on Madura Island, Indonesia's largest solar salt production island. The abundance of MPs found in seawater, sediment, and crude salt ranged between 0.17 and 0.59 items/L, 35.7 and 123.3 items/kg, and 35.0 and 111.7 items/kg, respectively. These levels are relatively lower compared to those found in other salt production regions. For instance, in China, MPs concentrations in salt range from 1000 to 2000 items/kg, and in India, they range from 470 to 1633 items/kg. This study also found that MPs in the form of fibres and fragments smaller than 50 μm were the most prevalent in all samples. In addition, black and blue polypropylene, high-density polythene (HDPE), and low-density polythene were the most common colours and types of MPs polymers. This research provides a baseline for the distribution of MPs on Madura Island, which can be used to mitigate the contamination of crude salt by MPs.