The first investigation of microplastics in G. affinis from the Brantas River was carried out in this study. Microplastics were found at higher concentrations in gambusia fish captured downstream (209.18 ± 48.85 particles/gram) than upstream (24.44 ± 0.14 particles/gram). Microplastic particle concentrations in G. affinis have a positive linear relationship with fish length. The fiber was the most prominent shape at Sites 1 and 2, whereas the fragment was dominant at Sites 3 and 4. With a value of 45–48%, black dominates the entire site, followed by blue (29–38%), transparent colors (7–11%), red (2–4%), purple (1–3%), and other colors (5–7%). Microplastics measuring <0.1 mm are commonly found in fish bodies. Cyclohexylmethyl octyl ester (phthalic acid) is the most abundant component found in microplastics, accounting for 30.11% of the total. This study provides evidence that G. affinis can be used to monitor the presence of microplastic pollution in the Brantas River but further studies are needed regarding the effects of microplastics and their health hazards on fish.

Amongst other threats, the world’s oceans are faced with man-made pollution, including an increasing number of microparticulate pollutants. Sponges, aquatic filter-feeding animals, are able to incorporate fine foreign particles, and thus may be a potential bioindicator for microparticulate pollutants. To address this question, 15 coral reef demosponges sampled around Bangka Island (North Sulawesi, Indonesia) were analyzed for the nature of their foreign particle content using traditional histological methods, advanced light microscopy, and Raman spectroscopy. Sampled sponges accumulated and embedded the very fine sediment fraction (<200 μm), absent in the surrounding sand, in the ectosome (outer epithelia) and spongin fibers (skeletal elements), which was confirmed by two-photon microscopy. A total of 34 different particle types were identified, of which degraded man-made products, i.e., polystyrene, particulate cotton, titanium dioxide and blue-pigmented particles, were incorporated by eight specimens at concentrations between 91 and 612 particle/g dry sponge tissue. As sponges can weigh several hundreds of grams, we conservatively extrapolate that sponges can incorporate on average 10,000 microparticulate pollutants in their tissue. The uptake of particles, however, appears independent of the material, which suggests that the fluctuation in material ratios is due to the spatial variation of surrounding microparticles. Therefore, particle-bearing sponges have a strong potential to biomonitor microparticulate pollutants, such as microplastics and other degraded industrial products.

In this study, size-fractionated particulate matters (PM) down to ultrafine (PM₀.₁) particles were collected using a cascade air sampler with a PM₀.₁ stage, in Hat Yai city, Songkhla province, southern Thailand during the year 2018. The particle-bound carbonaceous aerosols (CA) as elemental carbon (EC) and organic carbon (OC) were quantified with the thermal/optical reflectance method following the IMPROVE_TOR protocol. The concentrations of different temperature carbon fractions (OC1-OC4, EC1-EC3 and PyO) in the size-fractionated PM were evaluated to discern OC and EC correlations as well as those between char-EC and soot-EC. The results showed that biomass burning, motor vehicle, and secondary organic aerosols (SOC) all contributed to the size-fractionated PM. The OC/EC ratios ranged from 2.90 to 4.30 over the year, with the ratios of PM₂.₅₋₁₀ being the highest, except during the open biomass burning period. The concentration of CA was found to increase during the pre-monsoon season and had its peak value in the PM₀.₅₋₁.₀ fraction. The long-range transport of PMs from Indonesia, southwest of Thailand toward southern Thailand became more obvious during the pre-monsoon season. Transported plumes from biomass burning in Indonesia may increase the concentration of OC and EC both in the fine (PM₀.₅₋₁.₀ and PM₁.₀₋₂.₅) and coarse (PM₂.₅₋₁₀ and PM>₁₀) fractions. The OC fraction in PM₀.₁ was also shown to be significantly affected by the transported plumes during the pre-monsoon season. Good OC and EC correlations (R² = 0.824–0.915) in the fine particle fractions indicated that they had common sources such as fossil fuel combustion. However, the lower and moderate correlations (R² = 0.093–0.678) among the coarser particles suggesting that they have a more complex pattern of emission sources during the dry and monsoon seasons. This indicates the importance of focusing emission control strategies on different PM particle sizes in southern Thailand.

Sea turtles are globally endangered and face daily anthropogenic threats, including pollution. However, there is a lack of ecotoxicological information on sea turtles, especially in the Asia-Pacific region. This study aims to determine pollutant levels of foraging green turtles (Chelonia mydas) in South China, including Hong Kong, Guangdong and Taiwan, as a basis for their conservation. Scute, liver and muscle tissues of stranded green turtles were analysed for levels of 17 trace elements and methylmercury (MeHg) (n = 86 for scute and n = 14 for liver) and polybrominated diphenyl ethers (PBDEs) (n = 11 for muscle and n = 13 for liver). Ten-fold higher levels of Pb, Ba, V and Tl and 40-fold greater Cd levels were measured in green turtle livers in South China relative to other studies conducted over 10 years ago. Measured PBDE levels were also 27-fold and 50-fold greater than those reported in Australia and Japan. These results warrant further investigation of potential toxicological risks to green turtles in South China and their source rookeries in Malaysia, Micronesia, Indonesia, Marshall Islands, Japan and Taiwan. Research should target monitoring pollutant levels in sea turtles within the West Pacific/Southeast Asia regional management unit spanning East Asia to Southeast Asia to fill in knowledge gaps, in particular in areas such as Thailand, Vietnam, Indonesia, Malaysia and the Philippines where less or no data is available and where foraging grounds of sea turtles have been identified.

The Mesel gold mine in the Ratatotok Sub-district operated between 1996 and 2004 with tailings disposal via an engineered submarine tailings placement (STP) into Buyat Bay. This operation raised concerns of increased levels of arsenic (As) and mercury (Hg) associated disease in the local communities from consumption of seafood contaminated with anthropogenic As and Hg. This report uses the dietary exposure to As and Hg, from local fishermen and market-purchased Codex “as consumed” and environmental fish results from the pre-mining baseline (1990–1995), the mine operational (1996–2004) and post-closure monitoring (2007–2016) to examine the potential health effects. The Ratatotok Sub-district consumers total As average daily intake from fish was between 152 and 317 μg/day (adults) and 58 and 105 μg/day (infants). The average daily intake of inorganic arsenic (Asi) from the dietary staples fish and rice and drinking water consumption was 77 μg/day (adults) and 35 μg/day (infants) at Buyat Pantai and 39 μg/day (adults) and 19 μg/day (infants) at Ratatotok township. Fish consumption contributed 8.2% (adults) and 6.5% (infants) to total daily Asi intake. Average Hg intake from fish consumption, exceeded the FAO WHO PTWI for methylmercury (MeHg) for all age and gender groups at Buyat Pantai 4.6 μg/kg bw/wk (adults) and 7.3 μg/kg bw/wk (infants) and for the infants at Buyat village and Ratatotok township (2.5 and 2.8 μg/kg bw/wk respectively). The Manado City consumers had average intakes below the MeHg PTWI. The Hg exceedances resulted from the high fish consumption in coastal communities and not elevated levels of Hg in fish. Hg exposure levels from the pre-mining baseline, Mesel STP operation and post-closure monitoring, confirmed that exceedances were unrelated to the tailings deposited into Buyat Bay.

A study of 16 United States Environmental Protection Agency (USEPA) priority listed PAHs associated with particulate matter ≤ 10 μm (PM10) was conducted in Singapore during the period 29th May 2015 to 28th May 2016. The sampling period coincided with an extensive, regional smoke haze episode (5th September to 25th October) that occurred as a result of forest and peat fires in neighboring Indonesia. Throughout this study, 54 atmospheric PM10 samples were collected in 24 h periods using a high volume sampler (HVS) and quarts fiber filters (QFF) as the collection medium. Hysplit software for computing 3-D backward air mass trajectories, diagnostic ratio analysis and ring number distribution calculations were used to examine the sources of PAHs in the atmosphere in Singapore. Under normal conditions the total PAH concentrations were in a range from 0.68 ng m−3 to 3.07 ng m−3, while for the high haze period the results showed approximately double the concentrations with a maximum value of 5.97 ng m−3. Diagnostic ratio (DR) and principal component analysis (PCA) were conducted and indicated the contribution of the traffic as a dominant pyrogenic source of PAHs during normal periods, while results from the haze dataset showed relatively strong influence of smoke from peat and forest fires in Indonesia. Environmental and health risk from PAHs were assessed for both regular and hazy days.

The levels of nitrate in 52 drinking water wells in rural Central Java, Indonesia were evaluated in April 2014, and the results were used for a health risk assessment for the local populations by using probabilistic techniques. The concentrations of nitrate in drinking water had a range of 0.01–84 mg/L, a mean of 20 mg/L and a medium of 14 mg/L. Only two of the 52 samples exceeded the WHO guideline values of 50 mg/L for infant methaemoglobinaemia. The hazard quotient values as evaluated against the WHO guideline value at the 50 and 95 percentile points were HQ50 at 0.42 and HQ95 at 1.2, respectively. These indicated a low risk of infant methaemoglobinaemia for the whole population, but some risk for the sensitive portion of the population. The HQ50 and HQ95 values based on WHO acceptable daily intake dose for adult male and female were 0.35 and 1.0, respectively, indicating a generally a low level of risk. A risk characterisation linking birth defects to nitrate levels in water consumed during the first three months of pregnancy resulted in a HQ50/50 values of 1.5 and a HQ95/5 value of 65. These HQ values indicated an elevated risk for birth defects, in particular for the more sensitive population. A sanitation improvement program in the study area had a positive effect in reducing nitrate levels in wells and the corresponding risk for public health. For example, the birth defect HQ50/50 values for a subset of wells surveyed in both 2014 and 2015 was reduced from 1.1 to 0.71.

In this study, we assess the intense pollution episode of June 2013, in Riau province, Indonesia from land clearing. We relied on satellite retrievals of aerosols and Carbon monoxide (CO) due to lack of ground measurements. We used both the yearly and daily data for aerosol optical depth (AOD), fine mode fraction (FMF), aerosol absorption optical depth (AAOD) and UV aerosol index (UVAI) for characterizing variations. We found significant enhancement in aerosols and CO during the pollution episode. Compared to mean (2008–2012) June AOD of 0.40, FMF-0.39, AAOD-0.45, UVAI-1.77 and CO of 200 ppbv, June 2013 values reached 0.8, 0.573, 0.672, 1.77 and 978 ppbv respectively. Correlations of fire counts with AAOD and UVAI were stronger compared to AOD and FMF. Results from a trajectory model suggested transport of air masses from Indonesia towards Malaysia, Singapore and southern Thailand. Our results highlight satellite-based mapping and monitoring of pollution episodes in Southeast Asia.

Contamination status, potential emission sources, environmental fate, and human exposure risk of polybrominated diphenyl ethers (PBDEs) are reviewed for indoor and outdoor dust from Southeast Asian countries, under an international comparison point of view. PBDEs have been widely detected in house, workplace, car, and road dust samples collected from Indonesia, Philippines, Singapore, Thailand, and Vietnam. The highest PBDE levels up to hundreds of μg/g were found in settled dust from some e-waste processing areas in Thailand and Vietnam. Concentrations of PBDEs in house, car, and road dust from this region were generally lower than those reported in China and Western developed countries. BDE-209 was the most predominant congener in almost all analyzed samples, reflecting the widespread application of materials and products treated with commercial deca-BDE mixtures in this region. The market demand and application rate of commercial PBDE mixtures in Southeast Asia were lower than those documented for other regions in the world. As a result, PBDE contamination levels in the environments (e.g., indoor and outdoor dust) and associated risks in these countries were not significantly high. However, more attention should be paid to informal processing activities and management strategies for modern wastes such as e-waste, plastics, and end-of-life vehicles. There exist several knowledge gaps about spatiotemporal trends, potential sources, risk assessment, inventory, management, and legislation regarding PBDEs in dust from this region, which should be filled by additional comprehensive, detailed studies with relevant inter-country/regional monitoring schemes.

Beaches are key attractions for tourism and recreation, and considerable effort is made to keep beaches clean, yet many beaches still have substantial litter loads. Lasting solutions to reduce the amounts of marine litter require an understanding of litter sources. We collected bottles and other single-use containers at 32 sites around the South African coast to infer their sources based on their age and country of manufacture. Bottle densities varied greatly among beaches (8–450 bottles·km⁻¹), depending on proximity to local urban centres and beach cleaning frequency. Most bottles were plastic, despite well-developed recycling initiatives for PET and HDPE bottles in South Africa. Street litter was dominated by bottles made in South Africa (99%), but foreign-manufactured bottles comprised up to 74% of bottles at some beaches, with an increase from urban (4%) through semi-urban (24%) to remote beaches (45%). Most foreign bottles were PET drink bottles from China and other Asian countries, followed by South America and Europe, with little regional variation in the contribution from these sources. This fact, coupled with their recent manufacture dates (mainly <2 years old), indicates that most foreign PET drink bottles are dumped illegally from ships. By comparison, foreign HDPE bottles were more common along the southeast coast of South Africa than along the west coast, consistent with many of these bottles arriving by long-distance drift across the Indian Ocean from southeast Asia. The most common country of origin for these bottles was Indonesia, and most newly-arrived HDPE bottles were 4–6 years old. To tackle beach litter in South Africa we need to greatly reduce plastic leakage from land-based sources, both locally and in southeast Asia, as well as improve measures to prevent the illegal dumping of plastics and other persistent wastes from ships.