Microplastic pollution in the sediment of Jakarta Bay, Indonesia

During the COVID-19 pandemic, the increased use of plastic for personal protective equipment (PPE), single-use plastic bags, and food packaging raised significant environmental concerns. This study aimed to investigate the shape, abundance, and type of microplastics in the sediment of Jakarta Bay, specifically Tanjung Priok, Ancol Beach, and Sunda Kelapa Port. Sediment was collected using an Ekman sediment grab sampler and was extracted using the density separation method. The microplastics were counted and categorized according to the shape under a microscope. The differences in microplastic abundance in three different stations were determined using a one-way ANOVA. The polymer of microplastics was identified using Fourier Transform Infra-Red (FTIR). The results show that the abundance of the microplastics from coastal sediment was highest in the Sunda Kelapa Port (45066.67 ± 5205.13 particle/kg dry weight), which is significantly different (p<0.05) from Tanjung Priok (40533.33 ± 2444.04 particle/kg dry weight) and Ancol Beach (34666.67 ± 2444.04 particle/kg dry weight). Fragments dominated the shape of microplastic in Tanjung Priok, Ancol Beach, and Sunda Kelapa Post, comprising 36%, 40%, 38%, respectively, followed by fiber, film, and pellet. The FT-IR tests indicated that polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyamide are the most prevalent microplastic polymers.

Extraction and Identification of a Wide Range of Microplastic Polymers in Soil and Compost

Microplastic pollution is globally widespread; however, the presence of microplastics in soil systems is poorly understood, due to the complexity of soils and a lack of standardised extraction methods. Two commonly used extraction methods were optimised and compared for the extraction of low-density (polyethylene (PE)) and high-density microplastics (polyethylene (PET)), olive-oil-based extraction, and density separation with zinc chloride (ZnCl2). Comparable recoveries in a low-organic-matter matrix (soil; most >98%) were observed, but in a high-organic-matter matrix (compost), density separation yielded higher recoveries (98 ± 4% vs. 80 ± 11%). Density separation was further tested for the extraction of five microplastic polymers spiked at different concentrations. Recoveries were >93% for both soil and compost, with no differences between matrices and individual polymers. Reduction in levels of organic matter in compost was tested before and after extraction, as well as combined. Double oxidation (Fenton’s reagent and 1 M NaOH) exhibited the highest reduction in organic matter. Extracted microplastic polymers were further identified via headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS). This method has shown the potential for descriptive quantification of microplastic polymers. A linear relationship between the number of particles and the signal response was demonstrated for PET, polystyrene (PS), polyvinyl chloride (PVC), and PE (R2 > 0.98 in alluvial soil, and R2 > 0.80 in compost). The extraction and identification methods were demonstrated on an environmental sample of municipal biowaste compost, with the recovery of 36 ± 9 microplastic particles per 10 g of compost, and the detection of PS and PP.

Heavy metal recovery from the fine fraction of solid waste incineration bottom ash by wet density separation

This work is aimed at exploring the recovery of heavy metals from the fine fraction of solid waste incineration bottom ash. For this study, wet-discharged bottom ash fine-fraction samples from full-scale treatment plants in Germany and Sweden were analyzed. The potential for the recovery of heavy metal compounds was investigated through wet density-separation with a shaking table. The feed materials were processed without any pre-treatment and the optimum processing conditions were determined by means of design of experiments. Tilt angle and stroke frequency were identified as the most relevant parameters, and the optimum settings were − 7.5° and 266 rpm, respectively. The obtained balanced copper enrichments (and yields) were 4.4 (41%), 6.2 (28%) and 2.4 (23%). A maximum copper enrichment of 14.5 with 2% yield was achieved, providing a concentrate containing 35.9 wt.% relevant heavy metal elements. This included 26.3 wt.% iron, 4.3 wt.% zinc and 3.8 wt.% copper. In conclusion, density separation with shaking tables can recover heavy metals from bottom ash fine fractions. Medium levels of heavy metal enrichment (e.g., for Cu 2.7–4.4) and yield (Cu: 26–41%) can be reached simultaneously. However, the separation performance also depends on the individual bottom ash sample.

Comparison of Different Procedures for Separating Microplastics from Sediments

The separation of microplastics from environmental matrices is still challenging, especially for sediments where microplastics can accumulate affecting benthic organisms. Many authors have adopted different procedures, but their effectiveness has been rarely compared. The present study aims to compare the recovery rate of three different methodologies for the separation of dense microplastics from fine sediments and provide insights about contamination processes occurring in microplastic separation techniques. The protocols tested are a density separation method with NaCl and NaI, a density separation with NaI followed by a centrifugation step, and a digestion method with 10%KOH (m/v). The recovery yields of two high-density polymers of three different dimensional classes were tested. The highest recovery rate was reported for the first protocol. However, this method proved to be expensive, and unsatisfactory results were found when using merely NaCl. The digestion method was the one that was proven to be simple, reproducible, and affordable. The contamination tests highlighted as multiple filtration steps can increase the number of fibers deriving from airborne contamination. Since a unified approach for microplastic separation from sediments is still not selected, this study is of paramount importance as it provides data about the reliability of different methods widely adopted.

Spatial distribution and increase of microplastics over time in sediments of Buenaventura Bay, Colombian Pacific

The increase in production, consumption and inadequate disposition of plastics has generated an accumulation of these elements in marine ecosystems, which have become important microplastics sinks (< 5 mm). The objective of this research was to determine the temporal and spatial differences in the density, distribution, and type of microplastics in the sediments of Buenaventura Bay. For this purpose, sediment samples were collected in the internal estuary (close to the rivers) and in the external estuary (with a greater marine influence). Samples were obtained in the dry, transition, and rainy season for the years 2015 and 2019. Microplastics were extracted by density separation method, each particle was classified and measured by optical microscopy. Density ranged from 11 to 1,354 particles/kg, with averages of 194.9 ± 51.3 and 359.6 ± 88.0 particles/kg for the years 2015 and 2019, respectively, reporting an increase of 84.4 %. The internal estuary presented a higher density in both years and the fibers constituted the most common form of microplastic particles, with 63.7 % for 2015 and 56.03 % for 2019. The presence and increasing accumulation of microplastics generates risks and adverse effects for the marine communities; additionally it coul compromise the food safety for coastal human populations.

Spatial distribution and increase of microplastics over time in sediments of Buenaventura Bay, Colombian Pacific

The increase in production, consumption and inadequate disposition of plastics has generated an accumulation of these elements in marine ecosystems, which have become important microplastics sinks (< 5 mm). The objective of this research was to determine the temporal and spatial differences in the density, distribution, and type of microplastics in the sediments of Buenaventura Bay. For this purpose, sediment samples were collected in the internal estuary (close to the rivers) and in the external estuary (with a greater marine influence). Samples were obtained in the dry, transition, and rainy season for the years 2015 and 2019. Microplastics were extracted by density separation method, each particle was classified and measured by optical microscopy. Density ranged from 11 to 1,354 particles/kg, with averages of 194.9 ± 51.3 and 359.6 ± 88.0 particles/kg for the years 2015 and 2019, respectively, reporting an increase of 84.4 %. The internal estuary presented a higher density in both years and the fibers constituted the most common form of microplastic particles, with 63.7 % for 2015 and 56.03 % for 2019. The presence and increasing accumulation of microplastics generates risks and adverse effects for the marine communities; additionally it coul compromise the food safety for coastal human populations.