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Jakarta is an Indonesian coastal megacity with over 10 million inhabitants. The rivers flowing through the city receive enormous amounts of untreated wastewaters and discharge their pollutant loads into Jakarta Bay. We utilized a screening approach to identify those site-specific compounds that represent the major contamination of the cities' water resources, and detected a total number of 71 organic contaminants in Jakarta river water samples. Especially contaminants originating from municipal wastewater discharges were detected in high concentrations, including flame retardants, personal care products and pharmaceutical drugs. A flame retardant, a synthetic fragrance and caffeine were used as marker compounds to trace the riverine transport of municipal wastewaters into Jakarta Bay. These markers are also appropriate to trace municipal wastewater discharges to other tropical coastal ecosystems. This application is in particular useful to evaluate wastewater inputs from land-based sources to habitats which are sensitive to changing water quality, like coral reefs.

Non-target screening analyses were conducted in order to identify a wide range of organic contaminants in sediment and animal tissue samples from Jakarta Bay. High concentrations of di-iso-propylnaphthalenes (DIPNs), linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) were detected in all samples, whereas phenylmethoxynaphthalene (PMN), DDT and DDT metabolites (DDX) were detected at lower concentrations. In order to evaluate the uptake and accumulation by economic important mussel (Perna viridis) and fish species, contaminant patterns of DIPNs, LABs and PAHs in different compartments were compared. Different patterns of these contaminant groups were found in sediment and animal tissue samples, suggesting compound-specific accumulation and metabolism processes. Significantly higher concentrations of these three contaminant groups in mussel tissue as compared to fish tissue from Jakarta Bay were found. Because P. viridis is an important aquaculture species in Asia, this result is relevant for food safety.

Sediment geochemistry of the Jakarta region, a densely populated tropical coast, is studied — with particular focus on rivers discharging to Jakarta Bay. Weathering volcanics in the river catchment area control the composition of major elements, As, Cr and in part Cu. In contrast, Zn, Ni, Pb and partly Cu are affected by anthropogenic sources, mainly in central Jakarta City. The data reflect a high variability of local emission sources, among which metal processing industries, fertilizers or untreated animal waste may be important. In particular, the role of street dusts is emphasized. Locally, heavy metals reach levels considered to have adverse biological effects. River discharge leads to anthropogenic enrichment of heavy metals in the coastal sediments. Element data also show geogenic effects on the composition of the coastal sediments, such as mixing of detrital silicates with biogenic carbonates as well as suspended particulate matter from the ocean.

Jakarta, the capital of Indonesia, is one of the rapidly growing coastal megacities in Asia. The implementation of the urban wastewater infrastructure is not keeping up with the rapid expansion of the city, leading to a severe deterioration of water and sediment quality in the metropolitan area. The present study aimed to assess sediment contamination with organic pollutants in Jakarta rivers and the related risks to the coastal ecosystem. To this end, the site-specific and most harmful organic pollutants in the sediments were quantified, and the obtained chemical data were compared to reported sediment toxicity thresholds for an impact assessment on the benthic community. The detected pollutant spectrum included several compounds, such as the detergent residues nonylphenols and the insect repellent DEET (N,N-diethyl-m-toluamide), that were previously reported as contaminants in industrialized countries but have been banned or partly substituted. The risk of sediment contamination for benthic macroinvertebrates was associated with PAHs (polycyclic aromatic hydrocarbons), DDT (bis(chlorophenyl)dichloroethane), nonylphenols and a synthetic fragrance. High concentrations of paper manufacturing educts, a compound class that was recently reported in industrialized areas with a flourishing paper industry, were found in Jakarta sediments. However, sediment quality guidelines or sediment toxicity thresholds for these compounds are not available, which limited the ecotoxicological risk assessment. More studies on sediment toxicities considering emerging industrial pollutants and test species from all climate regions are urgently required, as a prerequisite for an adequate impact assessment of sediment contamination.