Spatial and temporal trends of microplastic contamination in surface sediment of Benoa Bay: An urban estuary in Bali-Indonesia.

This study aims to explore microplastic contamination in the sediments of Benoa Bay. Eight locations were sampled, with four duplications denoting the rainy and dry seasons. Based on observations, the microplastic concentration varied from 9.51 to 90.60 particles/kg with an average of 31.08 ± 21.53 particles/kg. The area near the landfill had the highest abundance, while the inlet and center of Benoa Bay and the Sama River had the lowest concentration. The fragments (52.2 %) and large microplastic sizes (64.7 %) were the most documented particles. We also identified 17 polymers, which dominated (37.5 %) by polyethylene, polypropylene, and polystyrene. There were no appreciable variations in abundance between seasons, although there were substantial variations in shape and size. Comprehensive investigation, adequate policies, continuous monitoring, and reducing waste from land- and sea-based sources that engage various stakeholders must be implemented urgently to prevent the release of microplastic into the aquatic ecosystem.

Multi-metals analysis in sediment of the North Sumatra coast, Indonesia: The environmental status.

This study aims to analyze multi-metals in marine sediment to provide the relative nature of metal concentrations. Sediment samples were collected in representative coasts of natural and more developing zones. The Sequential Extraction method was used to treat four metal associated hosts determined using the ICP-OES. Geo-accumulation index, Enrichment Factor and Principal Component analysis were used to evaluate. The metal concentrations varied and most of them appeared to show a gradual decrease from east, west to the isle coasts. The coastal environment has been recognized to contain non-residual associated metals suggesting the influence of anthropogenic metal input. These bioavailable fractions also show gradual decrease from the East coast to West and Isle coast. The environmental assessment reveals that most of these areas were categorized as unpolluted and concentration of some elements west and isle coast are relatively close to those of nature sediment.

The contribution of estuaries to the abundance of microplastics in Jakarta Bay, Indonesia.

Rivers are one of the main pollution routes to the ocean. This study examines the source of microplastics (MPs) in Jakarta Bay based on their characteristics and estimates MPs emissions from 9 estuaries around Jakarta Bay in 3 administrative areas (Tangerang, North Jakarta, and Bekasi). The sample used was the water's surface taken using a round net. The highest abundance was found in the Dadap River, and the lowest was in the Angke River. The characteristics of the MPs are dominated by fragments, the size of 300-500 µm, and composed of polyethylene. It shows that the MPs originate from the fragmentation of residents' plastic waste that has been in the waters for a quite long time. The nine estuaries also showed a high contribution to MPs in Jakarta Bay: from North Jakarta > Tangerang > Bekasi. The emission is highly correlated with water discharge and MPs' particles in each estuary.

The deposition of atmospheric microplastics in Jakarta-Indonesia: The coastal urban area.

The air pollution in Jakarta has been recorded regularly; meanwhile, the information of atmospheric microplastics is still unknown. This study examines the characteristics (shape, size, and polymer) and deposition rate of atmospheric microplastics in Jakarta. The sample was obtained by putting a rain gauge for 12 months. All microplastic samples were analyzed for polymer using FT-IR. The lowest to the highest percentage of atmospheric microplastic based on shape were foam

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.

Cadmium (Cd), Copper (Cu), and Zinc (Zn) levels in commercial and non-commercial fishes in the Blanakan River Estuary, Indonesia: A preliminary study.

The Blanakan River Estuary, located on the northern coast of West Java, receives heavy metals from anthropogenic activities nearby. This study investigates Cu, Cd, and Zn metals in water and their accumulation in fish (commercial and non-commercial). The samples (water and fish) were collected from seven sampling stations. The metals concentration in the surface water of the Blanakan River Estuary has exceeded the limit allowed by the Indonesian government. The average metal concentration sequence in commercial and non-commercial fish was Zn > Cu > Cd. In general, it was found that the concentration of Zn and Cd (Cu) metals in fish had (had not) exceeded the limits allowed by the FAO/WHO. Based on Bioconcentration Factor (BCF) value, all of fishes species have a low ability to accumulate heavy metals (BCF <1000). Based on Estimated Daily Intake (EDI), all fish species have a low risk for health, both for adult and children.

Concentration and adsorption of Pb and Cu in microplastics: Case study in aquatic environment.

Microplastics are proven as heavy metals vector, but the adsorption mechanism still unclear. This study investigated the adsorption of Pb and Cu in microplastics in the Musi River and the environment effect. This study was conducted in 10 stations along the Musi River to the estuary. The polymers of microplastics were dominated by PP and followed by PE, PES, PVC, and nylon. The average concentration of Pb (0.0347 mg L-1 for water and 0.470 mg kg-1 for microplastics) was higher than Cu (0.0138 mg L-1 for water and 0.091 mg kg-1 for microplastics). The highest concentration of both metals in water and microplastics were found in the estuary. Environment parameters have different effects on the adsorption. The present study found that the adsorption processes were following the Freundlich model. The interaction metal-microplastic was physisorption. Pb and Cu will attach through weak bonds and easy to release into the aquatic ecosystem.

Chromium in Benoa Bay, Bali - Indonesia.

The chromium (Cr) pollution in Bali gained public attention because the textile and screen-printing industry was reportedly dumping their waste into the river. Benoa Bay is the estuary of six rivers in Bali and is thought to be contaminated by Cr. In this research, we investigated the presence of Cr in surface water, sediment and plankton (as a base trophic level) in Benoa Bay, Bali. Thirty stations were used to investigate Cr in Benoa Bay. The results showed that at almost all stations, surface waters of Benoa Bay were not contaminated by Cr, meanwhile Cr was detected in plankton and sediment. This research found that the range of Cr concentrations was sediment > plankton > water. The Bioaccumulation Factor (BCF) between plankton-water was much higher than plankton-sediment.

Abundance and characteristics of microplastics in the northern coastal waters of Surabaya, Indonesia.

Microplastic distribution in waters gained increasing attention because of the discovery of microplastics in edible marine organisms. Microplastic size is small, and hence, it tends to float in the water column, thereby making it easy to enter and accumulate in the marine organism. Microplastic abundance is highly associated with the population density. The North Coast of Surabaya is the main area for community activities in East Java; therefore, it is highly vulnerable to receive microplastic input from the mainland. This study aimed to analyze the abundance, distribution, and characteristics of microplastics in the northern coastal waters of Surabaya. The study was conducted in March 2017. The results showed that the highest and lowest microplastic abundances were found in Lamong Bay. The microplastic characteristics in all stations showed that foam was the dominant form and polystyrene was the dominant type, with sizes of 500-1000 µm and 300-500 µm.