Spatial distribution and characterization of microplastics in subtidal sediments under stormwater discharge influence.

DÍAZ.JARAMILLO, M; RODRÍGUEZ, F.A.; PEGORARO, C.; ISLAS, MA. SOLEDAD; SUAREZ, AYELEN; GONZALEZ, MARIANA

Lanzarote/ virtual por COVID

Conferencia; Lanzarote and beyond. Fate and impacts of microplastics, knowledges and responsibilities.; 2020

Although microplastics are transported from land-based sources to aquatic environmentsthere is currently little knowledge about its fate from land sources to coastal marine waters.In addition to riverine discharges, storm drainages from urban settlements might contributean important source of microplastics. Mar del Plata city harbor (Buenos Aires, Argentina)holds the most important fishing fleet and shipyard facility in Argentina. Although thatseveral contaminants have been reported in sediments from this area, the occurrence ofmicroplastic has not be studied. The aim of this study was to evaluate the spatial distributionof microplastic in subtidal sediments (5-12 mt deep) from 4 sites in Mar del Plata?s harbor,differing in their distance to ?Del Barco? creek stormwater outlet. Microplastic contentwas determined (n:3 per site) by a density floating method using a zinc chloride (ZnCl2)solution (δ1.65). Mean total abundance of microplastics ranged from 1600 to 8700 items perkg d.w. Sediments from areas near to the discharge showed significantly higher abundances(p< 0.05) than those from distant sampling sites. Large (MPs, 1-5mm) and small (MMPs,1-0.1 mm) microplastics were observed in sediments from all sites. MPs were also at higherabundances in near outlets areas. In terms of shape, fragments (65-86%) and fibers (6.5-32.2%) forms were the dominant types, followed by films (1.9-5%), while beads and foamswere moderately or poorly represented (< 5%). Red (37.8 %), black (20.5%) and blue(11.5%) types were observed as the main color contribution among all microplastic particles insediments. These results represent the first analysis regarding the occurrence of microplasticsin Mar del Plata?s harbor and coast. Although, inputs from the in situ port activities couldnot be discarded, this study highlights the role of storm drain runoff in the transport anddeposition of microplastics to coastal areas.