Cytotoxic Effect of the Genus Sinularia Extracts on Human SCC25 and HaCaT Cells

Soft corals of the genus Sinularia are being increasingly adopted to treat a wide variety of disease processes. However, the mechanism underlying its activity against human oral cancer cells is poorly understood. This study evaluates the cyototoxicity effects of the genus Sinularia extracts (S. grandilobata, S. parva, S. triangula, S. scabra, S. nanolobata and S. gibberosa) by SCC25 and HaCaT cells. The cell adhesion assay indicates that extracts reduce the cell attachment. Extracts exhibit a dose-dependent cytotoxic effect using MTS assay.Treatment of extracts to observe the morphological alterations in cells, membrane blebbing, nuclear condensation, and apoptotic bodies is demonstrated. Flow cytometry shows that extracts sensitized the cells in the G0/G1 and G2/M phases with a concomitant significantly increased sub-G1 fraction, suggesting cell death by apoptosis. Extracts of the genus Sinularia thus apparently cause apoptosis of SCC25 and HaCaT cells, and warrant further research investigating the possible antioral cancer compounds in these soft corals

Trans-boundary air pollution in a Southeast Asian megacity: Case studies of the synoptic meteorological mechanisms and impacts on air quality

Local and regional sources contribute to degraded air quality in many urban areas, however, the influence of trans-boundary air pollution on surface PM2.5 is still poorly characterized in Southeast Asia (SEA) megacities. This study, for the first time, utilizes multi-platform datasets to elucidate two trans-boundary PM2.5 episodes in Ho Chi Minh City (HCMC), Vietnam, over the periods 25–29 Oct 2013 and 05–08 Oct 2015. Both events persisted with limited diurnal fluctuations and more than 60% of the Air Quality Index (AQI) values at an unhealthy level. PM2.5 concentrations during the events were 100% and 115% higher on average compared to local accumulation periods in the same months, highlighting the importance of trans-boundary pollution to local HCMC air quality. Backward trajectories, MERRA-2 AOD data, and CALIPSO images revealed the origin and synoptic meteorology conditions facilitating both trans-boundary pollution events. Anthropogenic PM2.5 emissions in continental East Asia fed the 2013 event, which was then transported by strong northeasterly winds triggered by an upper-level ridge near the Tibetan Plateau and a low-pressure system in western Pacific Ocean. In contrast, the 2015 event was the result of Indonesia biomass burning (BB), which was enhanced and transported by a westward propagating Western Pacific Subtropical High triggered by a strong El Nino ˜ event. Future climate change will likely increase the number of extreme El Nino ˜ events, leading to the increase of transboundary Indonesia BB events to HCMC. This study lays the groundwork for detailing the impact of trans-boundary pollution on local air quality in SEA megacities

Origin, Transport, and Vertical Distribution of Atmospheric Polluntants over the Northern Sourth China Sea During the 7-SEAS-Dongsha Experiment

During the spring of 2010, comprehensive in situ measurements were made for the first time on a small atoll (Dongsha Island) in the northern South China Sea (SCS), a key region of the 7-SEAS (the Seven South East Asian Studies) program. This paper focuses on characterizing the source origins, transport processes, and vertical distributions of the Asian continental outflows over the region, using measurements including mass concentration, optical properties, hygroscopicity, and vertical distribution of the aerosol particles, as well as the trace gas composition. Cluster analysis of backward trajectories classified 52% of the air masses arriving at ground level of Dongsha Island as having a continental origin, mainly from northern China to the northern SCS, passing the coastal area and being confined in the marine boundary layer (0-0.5 km). Compared to aerosols of oceanic origin, the fine mode continental aerosols have a higher concentration, extinction coefficient, and single-scattering albedo at 550 nm (i.e., 19 vs. 14 microg per cubic meter in PM(sub 2.5); 77 vs. 59 M per meter in beta(sub e); and 0.94 vs. 0.90 in omega, respectively). These aerosols have a higher hygroscopicity (f at 85% RH = 2.1) than those in the upwind inland regions, suggesting that the aerosols transported to the northern SCS were modified by the marine environment. In addition to the near-surface aerosol transport, a significant upper-layer (3-4 km) transport of biomass-burning aerosols was observed. Our results suggest that emissions from both China and Southeast Asia could have a significant impact on the aerosol loading and other aerosol properties over the SCS. Furthermore, the complex vertical distribution of aerosols-coinciding-with-clouds has implications for remote-sensing observations and aerosol-cloud-radiation interactions

An Overview of Regional Experiments on Biomass Burning Aerosols and Related Pollutants in Southeast Asia: From BASE-ASIA and the Dongsha Experiment to 7-SEAS

By modulating the Earth-atmosphere energy, hydrological and biogeochemical cycles, and affecting regional-to-global weather and climate, biomass burning is recognized as one of the major factors affecting the global carbon cycle. However, few comprehensive and wide-ranging experiments have been conducted to characterize biomass-burning pollutants in Southeast Asia (SEA) or assess their regional impact on meteorology, the hydrological cycle, the radiative budget, or climate change. Recently, BASEASIA (Biomass-burning Aerosols in South-East Asia: Smoke Impact Assessment) and the 7-SEAS (7- South-East Asian Studies) Dongsha Experiment were conducted during the spring seasons of 2006 and 2010 in northern SEA, respectively, to characterize the chemical, physical, and radiative properties of biomass-burning emissions near the source regions, and assess their effects. This paper provides an overview of results from these two campaigns and related studies collected in this special issue, entitled Observation, modeling and impact studies of biomass burning and pollution in the SE Asian Environment. This volume includes 28 papers, which provide a synopsis of the experiments, regional weatherclimate, chemical characterization of biomass-burning aerosols and related pollutants in source and sink regions, the spatial distribution of air toxics (atmospheric mercury and dioxins) in source and remote areas, a characterization of aerosol physical, optical, and radiative properties, as well as modeling and impact studies. These studies, taken together, provide the first relatively complete dataset of aerosol chemistry and physical observations conducted in the sourcesink region in the northern SEA, with particular emphasis on the marine boundary layer and lower free troposphere (LFT). The data, analysis and modeling included in these papers advance our present knowledge of source characterization of biomass-burning pollutants near the source regions as well as the physical and chemical processes along transport pathways. In addition, we raise key questions to be addressed by a coming deployment during springtime 2013 in northern SEA, named 7-SEASBASELInE (Biomass-burning Aerosols Stratocumulus Environment: Lifecycles and Interactions Experiment). This campaign will include a synergistic approach for further exploring many key atmospheric processes (e.g., complex aerosol-cloud interactions) and impacts of biomass burning on the surface-atmosphere energy budgets during the lifecycles of biomass burning emissions

A New Monitoring Effort for Asia: The Asia Pacific Mercury Monitoring Network (APMMN)

The Asia Pacific Mercury Monitoring Network (APMMN) cooperatively measures mercury in precipitation in a network of sites operating in Asia and the Western Pacific region. The network addresses significant data gaps in a region where mercury emission estimates are the highest globally, and available measurement data are limited. The reduction of mercury emissions under the Minamata Convention on Mercury also justifies the need for continent-wide and consistent observations that can help determine the magnitude of the problem and assess the efficacy of reductions over time. The APMMN’s primary objectives are to monitor wet deposition and atmospheric concentrations of mercury and assist partners in developing their own monitoring capabilities. Network planning began in 2012 with wet deposition sampling starting in 2014. Currently, eight network sites measure mercury in precipitation following standardized procedures adapted from the National Atmospheric Deposition Program. The network also has a common regional analytical laboratory (Taiwan), and quality assurance and data flagging procedures, which ensure the network makes scientifically valid and consistent measurements. Results from our ongoing analytical and field quality assurance measurements show minimal contamination in the network and accurate analytical analyses. We are continuing to monitor a potential concentration and precipitation volume bias under certain conditions. The average mercury concentration in precipitation was 11.3 (+9.6) ng L−1 for 139 network samples in 2018. Concentrations for individual sites vary widely. Low averages compare to the low concentrations observed on the U.S. West Coast; while other sites have average concentrations similar to the high values reported from many urban areas in China. Future APMMN goals are to (1) foster new network partnerships, (2) continue to collect, quality assure, and distribute results on the APMMN website, (3) provide training and share best monitoring practices, and (4) establish a gaseous concentration network for estimating dry deposition