Microplastics in sinking particulate matter of the Inner Sea in the Maldives

, Fischer Elke, Pfeiffer Felix, Wiesner Martin.

The Maldives with 1,190 small islands grouped in two chains of 26 atolls that surround the so-called Ïnner Seä. In the context of this stunning beauty, the question of waste management arises. According to UNICEF (2019), 280,000 plastic bottles are used and discarded daily in the capital Malé alone. Statistical data from the Maldives Customs Service documents that 325 million plastic bags were imported into the Maldives in the years 2006 - 2010 (Zuhair, 2011); imports increased dramatically to 104 million plastic bags in 2018 (UNICEF 2019). Due to this extensive consumption and the mismanagement of waste, even uninhabited islands of the archipelago are littered with plastic. Efforts to reduce this problem are ongoing. While large plastic objects on beaches and in the water are easy to spot, there is a growing need for knowledge about the microplastic contamination of the Inner Sea. Within the framework of the BMBF-funded project M̈aldivian Monsoon and Carbonate Platform Processes̈ (Institute of Geology of the University of Hamburg), two mooring arrays were deployed in the northern and southern part of the Inner Sea in 2014. Sediment traps were attached to the moorings at depths of 80 and 200 m and programmed to collect sinking particulate matter at 18-day intervals for one year. The time series covers the SW- and NE-monsoon seasons with strong fluctuations in precipitation, wind strength, aeolian input, surface and deep-water currents, primary productivity and inflow of water from the Arabian Sea and the Bay of Bengal. Accompanying, sub-samples of the trapped material will be analysed qualitatively and quantitatively for plastic particles in the laboratories of the MRC. Preliminary results show that microplastics are ubiquitously present in relevant concentrations. Besides the development of an adopted digestion method, type- and size-specific analyses of the particles using RAMAN spectroscopy are implemented.

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