Now that microplastics have been detected in lakes, rivers, and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates with different species traits, using a wide range of microplastic concentrations. Standardized 28 days single species bioassays were performed under environmentally relevant exposure conditions using polystyrene microplastics (20–500 μm) mixed with sediment at concentrations ranging from 0 to 40% sediment dry weight (dw). Microplastics caused no effects on the survival of Gammarus pulex, Hyalella azteca, Asellus aquaticus, Sphaerium corneum, and Tubifex spp. and no effects were found on the reproduction of Lumbriculus variegatus. No significant differences in growth were found for H. azteca, A. aquaticus, S. corneum, L. variegatus, and Tubifex spp. However, G. pulex showed a significant reduction in growth (EC₁₀ = 1.07% sediment dw) and microplastic uptake was proportional with microplastic concentrations in sediment. These results indicate that although the risks of environmentally realistic concentrations of microplastics may be low, they still may affect the biodiversity and the functioning of aquatic communities which after all also depend on the sensitive species.

Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were determined in the sediments and brackish water of Citarum Irrigation System (CIS), Pakis Jaya, Karawang Regency. The samples were analyzed with liquid-liquid extraction for brackish water and Soxhlet Extraction for sediments. The final concentration of PAHs was determined with Gas Chromatography-Mass Spectrometry (GC-MS) and the origins of PAHs were identified through diagnostic ratios method. The total PAH concentrations ranged from 1782 to 2386.88 ng/L in water and from 113 to 405 ng/g dry weight (dw) in sediments. The concentration of total PAHs in sediment was lower than the SQG effects range-low (3442 ng/g). High molecular weight of PAHs dominated both in sediments and water. The origins of PAHs in the sediment and water-based on diagnostic ratios were from petrogenic and pyrogenic sources including petroleum, petroleum combustion, and combustion of organic materials. Overall, environmental conditions in the Citarum irrigation system and its river mouth was moderate level of PAHs contamination.

Indonesia has a variety of coastal systems such as coral reef, mangrove, seagrass, mudflat, and dune, each of which has high biodiversity of species. The primary concern in Indonesia is that rapid economic growth would endanger some essential natural ecosystems and resources, and cause deterioration of environmental condition. As a part of bioindicator development to recognize pollutants with small fish of the genus Oryzias, this study was conducted to assess baseline status of PAHs distribution and sources in seawater, sediments and Oryzias fish. The ecological risk of PAHs in sediments was also evaluated. Concentrations of fifteen USEPA PAH based on GCMS analysis in seawater, sediments, and Oryzias fish vary from 0.00 to 30,600 ng/l, 6.7 to 138.6 ng/g dry weight (dw) and 25.2 to 30.5 ng/g dw, respectively. Based on the diagnostic ratio of PAH compounds, the potential sources of PAHs originated mainly from pyrogenic sources. The status of sediment from this Oryzias fish habitat was considered to be low polluted with PAHs.

The paper reports the concentrations of PAHs in 27 stations of surface marine sediments on three areas (Bondet, Sukalila, and Kejawan) around Cirebon coastal waters, West Java, Indonesia in April 2017. The results showed that the total PAH concentrations in the sediment from three areas ranged from below detection limit (<0.002 ng/g wet weight (ww)) to 42.19 ng/g ww, with a mean of 5.53 ng/g ww, respectively. The highest concentration of PAHs was recorded in surface sediments from the sampling site around Sukalila coastal waters with an average of 7.69 ng/g ww. As for the compound distribution of PAHs, the highest molecular weight of PAHs with rings more than three were the most dominant compounds observed at three coastal areas. This indicates their sources came from mixture of biomass combustion and petroleum. Further research to obtain comprehensive results for sustainable environmental management is needed to include other factors such as physical oceanography, sediment characteristics, and sediment transport.