Abstract

VIDAL, Laura; MOLINA, Andrés  and  DUQUE, Guillermo. Increase in microplastic pollution in the surface waters of Buenaventura Bay, Colombian Pacific. Bol. Invest. Mar. Cost. [online]. 2021, vol.50, n.2, pp.113-132.  Epub Dec 03, 2021. ISSN 0122-9761.  https://doi.org/10.25268/bimc.invemar.2021.50.2.1032.

Microplastic (MP) pollution in coastal ecosystems is a serious problem throughout the world. In Colombia, there is little information on this issue, especially for the Pacific coast. For these reasons, the density, distribution, and types of MP on the surface of the water were studied in the bay of Buenaventura estuary, Colombia’s main seaport. A total of 36 samples were collected in two estuarine areas: the inner estuary (IE), closest to the main urban area and river mouths, and the external estuary (EE), further away from both areas, during three seasons: rainy, transition, and dry, in 2015 and 2019. On average, the density of the MP increases annually by 28.7 % in the surface waters of Buenaventura Bay. It was also found that the highest densities of MP occurred mainly in the rainy season (664,766.7 ± 129,828.1 particles/km²) and transition (320,386.5 ± 59,313.7 particles/km²), while in the dry season the densities were lower (160,899 ± 43,606 particles/km²), due to increased runoff in times of higher rainfall. In both years, MP concentration increased the further from the inner zone of the bay the sample was taken, with a lower density observed in the IE (271,928.6 ± 60,734.9 particles/km²) and a higher density in the EE (492,106.2 ± 98,467.1 particles/km²). The MP found were classified into fragments, fibers, and pellets, according to their shape. In the IE, there was a greater quantity of fibers, while in the EE, fragments where the most common MP shape. The types of MP that were more abundant on the surface were fragments (62.2 %) and fibers (37.4 %), possibly due to their low density compared to the density of the estuarine water.

Keywords : Buenaventura Bay; microplastics; spatial variation; climate seasons; monitoring..

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