Stranded marine debris on the touristic beaches in the south of Bali Island, Indonesia: The spatiotemporal abundance and characteristic.

Stranded marine debris (MD) has become a hot topic on Bali Island because it threatens coastal tourism sustainability. This study aims to investigate the spatiotemporal abundance and characteristics of MD on 14 touristic beaches in Bali Island. Sampling is carried out twice every season by adapting methods from NOAA's MD program. We found that the average MD abundance and weight were 0.356 ± 0.366 items/m2 and 4.057 ± 3.892 g/m2, respectively. Plastic dominated the MD based on abundance (86.9%) and weight (40.1%). Plastic bags, straws, and plastic cups are the most common items among plastics. The MD is originated from Indonesia and is dominated by land-based sources. The beaches are categorized as dirty in the rainy seasons and clean in the dry seasons. Statistically, the MD based on abundance, weight, category, source, and level of cleanliness varied significantly between seasons.

Spatial and temporal distribution of microplastic in surface water of tropical estuary: Case study in Benoa Bay, Bali, Indonesia.

In 2010, Indonesia estimated as the second-largest country in the world that donates plastic to the sea. This study aims to investigate the spatial and temporal distribution of microplastics in tropical estuaries. The sampling was carried out in Benoa Bay with four repetitions representing the wet and dry seasons. Spatially it was found that the highest microplastic abundance around the Suwung landfill, while the lowest at Badung River Estuary, middle, and an inlet of the Benoa Bay. The highest percentage to the lowest microplastic based on the size was 500-1000 µm (37.9%), >1000 µm (35.7%), 300-500 µm (22.1%), and <300 µm (4.3%), while based on the shape were fragments (73.19%), foam (17.02%), fiber (6.38%), and granule (3.40%). No significant differences were found between the wet and dry seasons based on the abundance, but significantly varied based on size and shape. Polymers of microplastics were dominated by polystyrene, polypropylene, and polyethylene.

Seasonal distribution and geochemical fractionation of heavy metals from surface sediment in a tropical estuary of Jeneberang River, Indonesia.

Lead (Pb) and zinc (Zn) concentrations from surface sediments were determined at 17 stations in riverine, estuarine, and marine environments during the wet and dry seasons. The geochemical fractionations were obtained by a sequential extraction procedure in five geochemical forms: exchangeable, bound to carbonate, iron-manganese oxide, organic, and residual fractions. The concentrations of Pb and Zn in the water were higher during the wet season than the dry season and higher in the riverine and marine samples than the estuarine samples. Following geochemical fractionation, the metals were found mainly in the residual fraction. The results indicated that the concentrations were influenced by season, with the sources of Pb and Zn derived mainly from rivers and natural sources. The contamination status in the estuary of the Jeneberang River was classified as weak to moderate pollution and the risk level to aquatic biota attributed was no risk to low risk.