Case Study of Microplastics on Blood Cockle from Three Traditional Markets in Semarang

Many studies showed that food product sold in the market contained microplastics. Commercial products which contaminated wih microplastics have potential for physical and chemical hazards so it can threaten food safety. Bivalves usually become the main key species which reflect the status of marine environment in marine monitoring program. Bivalves usually become an important key species which reflect the status of marine environment in marine monitoring program. Bivalves are filter feeder so they can be bioindicator to detect levels of toxicity in their habitat. Blood cockle is the most common type of bivalves sold in Semarang. This research focused on assessing microplastic concentration from blood cockle from three traditional markets in Semarang This study is part of the microplastic risk assessment study in blood cockle in Semarang inhabitants. Result from this research latter will be used to measure microplastic exposure toward Semarang citizen. Blood cockle sampling was done by purposive random sampling from Karang Ayu Market, Peterongan Market and Bulu Market, and a seafood seller was chosen randomly from each. Amount of cockle bought from one market was about 3 kg and 30 organisms were chosen from those with similar length shell. The cockle tissues were digested with 10% KOH solution (1:10, sample to alkaline solution) and they were incubated in 40 ºC for 48 hours. The following step was microplastics isolation by filtration using Sartorius paper grade 388, then adding 4.4 M NaI solution and followed by several treatments such as sonication, agitation, centrifugation and filtration again so the microplastics were floated and separated from the organic matter. Every filtration was using Sartorius filter paper grade 388. After that, the physical appearance of particles could be identified under microscope. The result of this study showed that the Particle Suspected as Microplastic (PSM) found in blood cockle from Bulu Market (23,17 ± 13,02 particle/organism), Peterongan Market (20,93 ± 9,80 particle/organism) and Karang Ayu Market (9,87 ± 4,76 particle/ organism). The most abundant PSM found in the form of fragment, followed by film, pellet, fiber and foam particles respectively. The longest size of PSM found was fiber, followed by film, fragment and pellet. The biggest size of PSM found based on their surface area was film, followed by fragment, fiber and pellet. The most dominant PSM were found in the size range of 20 – 50 μm (48,5%) and <20 μm (24,3%). The smaller size makes this microplastic easier to translocated