The Effect of Geomembrane Plastic Usage on Microplastic and Heavy Metal Contamination in Salt Field

Abstract Seawater is used to produce salt. For 10–15 years, geomembrane plastic has been used in salt fields in Indonesia to prevent contamination and increase quality and productivity. However, it is unfortunate that currently, seawater has been polluted by plastic waste, which has degraded gradually into small pieces about <5 mm in size called microplastics. In addition to microplastics, seawater is also polluted by heavy metals. Previous research indicated that the north coast of Central Java has been polluted by heavy metals whose content exceeded the threshold. The aim of this study was to analyze the amount of microplastic (MPs) and heavy metal contamination in salt. A microscope was used to measure the amount of MPs and AAS was used to measure the concentration of heavy metals. Variables that were conducted included sampling location (4 locations) and crystallization process (with and without using geomembrane). The results showed that the amount of MPs salt with a geomembrane was higher than without a geomembrane, at 337 and 326 particles/kg, respectively. The average is 332 particles/kg. Salts that use geomembranes have more contamination than salts without geomembranes. Heavy metal contamination of Pb, Cd, Hg, As, all of which were still within the threshold. The average Pb and Cd concentration in salts with and without geomembranes were 4.11 mg/kg and 4.14 mg/kg; 0.65 and 1.05, respectively. Meanwhile, the average of Hg and As concentrations for both were below than 0.001 and 0.005 mg/kg, respectively.