Risk Assessment of Total Mercury (T-Hg) in Commercial Seafood Marketed in Bangkok, Thailand

Seafood is recognized as the high protein source of human consumption. However, it is hampered by mercury contamination. The objectives of this study are to determine total mercury (T-Hg) levels in edible portions of commercial seafood available in Bangkok’s supermarkets, and to evaluate the potential risks from mercury through seafood consumption. Total 32 species, including 22 fish, 4 cephalopod and 6 shellfish, were purchased from super-markets. Fish samples were dissected in 3 parts comprised of flesh, gill and viscera. While, cephalopod and shellfish were separated for edible tissues. The samples were digested in hot acid and were determined using cold-vapor atomic absorption spectrometry technique. The results revealed that T-Hg contained in the fish flesh > cephalopod > shellfish. In addition, T-Hg was accumulated in flesh > viscera > gill. Statistical analysis suggested that T-Hg accumulated in flesh was related positively with species, feeding habit, and habitat (p < 0.05). For risk analysis, estimated daily intake (EDI) of flesh ranged from 0.01 to 0.42 µg kg-1 bodyweight d-1, the lowest and highest EDI values were in salmon and yellowfin tuna, res-pectively. Yellowfin tuna, narrow-barred Spanish mackerel, fourfinger threadfin, and silver sillago were the 4 species that having the EDI values of T-Hg higher than the FAO/WHO recommended provisional tolerable daily intake (PTDI) of 0.23 µg kg-1 bodyweight d-1. Thus, the frequent consumption of these seafood are not recommended. In addition, the daily consumption of seafood should not exceed the maximum safe daily intake (MSDC). The MSDC of seafood in this study ranged from 15.5 (yellowfin tuna) to 474 (salmon) g d-1

Mercury content and consumption risk of 8 species threadfin bream (Nemipterus spp.) caught along the Gulf of Thailand

Total mercury (T-Hg) was examined in 8 threadfin bream species (Nemipterus spp.) caught in the Gulf of Thailand (GoT). The T-Hg contents ranged from 11.3 to 374 μg kg−1 wet weight, with the lowest in Nemipterus peronii and the highest in Nemipterus nemurus and Nemipterus tambuloides. Accumulation of T-Hg in fish tissue was found to be related to fish size, trophic levels, feeding habits and habitat. Threadfin bream caught in the upper GoT exhibited significantly (p −1 bodyweight day−1. All threadfin breams in the GoT have HQ −1

Metal concentrations and source apportionment of PM2.5 in Chiang Rai and Bangkok, Thailand during a biomass burning season

One of the persistent environmental problems in the provinces of northern Thailand is severe air pollution during the dry season because of open vegetation burning by farmers for land clearance purpose. Aerosol optical depth and Ångström exponent data from MODIS-Terra satellite indicated that from mid-March to April, 2019, entire Thailand was covered with a high concentration of fine-sized aerosols. Trace metal concentrations of PM2.5 collected from Chiang Rai in northern Thailand and Bangkok in southern Thailand between January and April 2019 were analyzed. Average concentrations of crustal metals such as Al, Ca, and Fe are higher in Chiang Rai compared to that in Bangkok. The Fe/Al ratio in Chiang Rai decreases from 1.65 during the onset of haze to 0.87 during the peak haze approaching a crustal ratio of 0.48. In contrast, Bangkok has higher Na, Mg, and Zn with an average Na/Mg ratio of 6.07 indicative of a sea spray (Na/Mg ∼ 8) origin. Principal component analysis identifies three possible sources in Chiang Rai: (1) crustal dust and biomass burning, (2) industrial source, and (3) refuse incineration mixed with road dust; and for Bangkok (1) natural background, industrial emissions, and coal combustion, (2) traffic emission, and (3) sea spray. The ranges of Pb isotope ratios in the bulk fraction of PM2.5 in Chiang Rai (206Pb/207Pb = 1.1445–1.1657 and 208Pb/207Pb = 2.4244–2.4468) and Bangkok (206Pb/207Pb = 1.1343–1.1685 and 208Pb/207Pb = 2.4138–2.4450) are not significantly different. However, in a time series plot, 206Pb/207Pb ratios in Chiang Rai follow PM2.5 during the peak burning season and correlate well with the Al/Pb (r2 = 0.61) ratios, indicating that at least part of the Pb is derived from crustal dust during peak fire. Using a binary mixing model, the most radiogenic Pb isotopes in Chiang Rai during the peak haze can be explained by ∼5 to 30% mixing of crustal dust with ∼35–40% biomass burning generated aerosols with the background. From the trace metal systematics and Pb isotope ratios, it is evident that (1) during the biomass burning season, trace metals from Chiang Rai are not transported down south to Bangkok and (2) in addition to metals released from biomass burning, the raging fire remobilizes crustal dust that forms an important source of Pb and other trace metals in the Chiang Rai aerosol.Ministry of Education (MOE)Accepted versionThis research has been supported by a Singapore Ministry of Education (MOE) Tier 1 grant (MOE-NTU_RG125/16-(S)), Department of Science & Technology (DST, Govt of India) (RTF/2019/000052), Centre of Excellence on Hazardous Substance Management and the 90th Anniversary (Ratchadaphiseksomphot Endowment Fund) of Chulalongkorn University Funds. JK was supported by the Science Achievement Scholarship of Thailand (SAST). The authors also thank the research groups of MODIS for providing the data and HYSPLIT for providing software for back-trajectory computations. The authors would also like to thank Mr. Pornsak Bureekul for collecting the sample from Chiang Rai and Ms. Lin Ke for keeping the chemistry lab and instruments in impeccable conditions. Baan Hom Muen Lee Resort in Chiang Rai (http://www.baanhommuenlee.com/) kindly provided us with the pictures of clear day and hazy day in Chiang Rai used in the TOC graphics

Priorities to inform research on marine plastic pollution in Southeast Asia

Southeast Asia is considered to have some of the highest levels of marine plastic pollution in the world. It is therefore vitally important to increase our understanding of the impacts and risks of plastic pollution to marine ecosystems and the essential services they provide to support the development of mitigation measures in the region. An interdisciplinary, international network of experts (Australia, Indonesia, Ireland, Malaysia, the Philippines, Singapore, Thailand, the United Kingdom, and Vietnam) set a research agenda for marine plastic pollution in the region, synthesizing current knowledge and highlighting areas for further research in Southeast Asia. Using an inductive method, 21 research questions emerged under five non-predefined key themes, grouping them according to which: (1) characterise marine plastic pollution in Southeast Asia; (2) explore its movement and fate across the region; (3) describe the biological and chemical modifications marine plastic pollution undergoes; (4) detail its environmental, social, and economic impacts; and, finally, (5) target regional policies and possible solutions. Questions relating to these research priority areas highlight the importance of better understanding the fate of marine plastic pollution, its degradation, and the impacts and risks it can generate across communities and different ecosystem services. Knowledge of these aspects will help support actions which currently suffer from transboundary problems, lack of responsibility, and inaction to tackle the issue from its point source in the region. Being profoundly affected by marine plastic pollution, Southeast Asian countries provide an opportunity to test the effectiveness of innovative and socially inclusive changes in marine plastic governance, as well as both high and low-tech solutions, which can offer insights and actionable models to the rest of the world.Additional co-authors: Simon M. Cragg, Neil Dickson, Pierre Failler, Gianluca Ferraro, Stephen Fletcher, Jenny Fong, Alex T. Ford, Tony Gutierrez, Fauziah Shahul Hamid, Jan G. Hiddink, Pham T. Hoa, Sophie I. Holland, Lowenna Jones, Nia H. Jones, Heather Koldewey, Federico M. Lauro, Matt Lewis, Danny Marks, Claudia G. Mayorga-Adame, John McGeehan, Laura Michie, Michelle A. Miller, Zeeda F. Mohamad, Nur Hazimah Mohamed Nor, Moritz Müller, Simon P. Neill, Sarah E. Nelms, Deo Florence L. Onda, Joyce J.L. Ong, Agamuthu Pariatamby, Sui C. Phang, Peter E. Robins, Maria Salta, Aida Sartimbul, Shiori Shakuto, Martin W. Skov, Evelyn B. Taboada, Peter A. Todd, Tai Chong Toh, Suresh Valiyaveettil, Voranop Viyakarn, Passorn Wonnapinij, Louisa E. Wood, Clara L.X. Yong, Brendan J. Godle

Corrigendum to “Priorities to inform research on marine plastic pollution in Southeast Asia” [Sci. Total Environ. volume 841 (2022) Article 156704]

10.1016/j.scitotenv.2022.159595SCIENCE OF THE TOTAL ENVIRONMENT857Pt

Priorities to inform research on marine plastic pollution in Southeast Asia

10.1016/j.scitotenv.2022.156704Sci Total Environ841156704