Influence of Sea-Land Breezes on the Tempospatial Distribution of Atmospheric Aerosols over Coastal Region

Abstract

The influence of sea-land breezes (SLBs) on the spatial distribution and temporal variation of particulate matter (PM) in the atmosphere was investigated over coastal Taiwan. PM was simultaneously sampled at inland and offshore locations during three intensive sampling periods. The intensive PM sampling protocol was continuously conducted over a 48-hr period. During this time, PM 2.5 and PM 2.5-10 (PM with aerodynamic diameters Յ2.5 m and between 2.5 and 10 m, respectively) were simultaneously measured with dichotomous samplers at four sites (two inland and two offshore sites) and PM 10 (PM with aerodynamic diameters Յ10 m) was measured with ␤-ray monitors at these same 4 sites and at 10 sites of the Taiwan Air Quality Monitoring Network. PM sampling on a mobile air quality monitoring boat was further conducted along the coastline to collect offshore PM using a ␤-ray monitor and a dichotomous sampler. Data obtained from the inland sites (n ϭ 12) and offshore sites (n ϭ 2) were applied to plot the PM 10 concentration contour using Surfer software. This study also used a three-dimensional meteorological model (Pennsylvania State University/National Center for Atmospheric Research Meteorological Model 5) and the Comprehensive Air Quality Model with Extensions to simulate surface wind fields and spatial distribution of PM 10 over the coastal region during the intensive sampling periods. Spatial distribution of PM 10 concentration was further used in investigating the influence of SLBs on the transport of PM 10 over the coastal region. Field measurement and model simulation results showed that PM 10 was transported back and forth across the coastline. In particular, a high PM 10 concentration was observed at the inland sites during the day because of sea breezes, whereas a high PM 10 concentration was detected offshore at night because of land breezes. This study revealed that the accumulation of PM in the near-ocean region because of SLBs influenced the tempospatial distribution of PM 10 over the coastal region.

Seasonal Variation of Criteria Pollutant in an Urban Coastal Environment: Kuala Terengganu

“…As we can see in Table 2, the annual variations for the criteria pollutants does not fluctuates much in the past 10 years except for PM 10 . The concentration for PM 10 exceeded the MAAQG of 50 μg/m 3 in eight out of the ten years whereas other criteria pollutants recorded concentrations way below the MAAQG ( Table 2).…”

“…PM 10 and O 3 have the highest concentration in December and January while NO 2 and SO 2 recorded higher concentrations in May, and July. As for CO, two peaks that fall in month February and August were noticed.…”

“…The concentration for PM 10 exceeded the MAAQG of 50 μg/m 3 in eight out of the ten years whereas other criteria pollutants recorded concentrations way below the MAAQG ( Table 2). As the study area is an urban coastal environment, the main contributors of PM 10 are not only local sources such as traffic aerosols, biomass burning, soil dust, vehicle exhaust and secondary aerosols but a high amount of the concentration were originating from the sea sprays [18], [19].…”

“…The highest concentration for PM 10 was recorded in January 2002. Although Malaysia is experiencing moderate Northeast monsoon, the Northern ASEAN regions were dominated by dry weather conditions where hotspots were detected in Cambodia, Laos PDR, Myanmar, and Thailand due to the El Nino occurrence.…”

“…Based on the Environmental Quality Report of the year 2013, the concentration of the criteria pollutants often exceeds the Malaysia Ambient Air Quality Guidelines and the most prominent pollutant that frequently causes the moderate air quality days in Malaysia is particulate matter. Motor vehicles, abrasion of tires and brakes, marine aerosols, agricultural activities and even cooking contributes to a significant amount of PM, biomass burnings produces CO, whereas industrial activities and power plants are the major contributors of aerosols such as SO 2 , NO 2 and O 3 forming pollutants [7]- [10]. The ambient air quality management policies are the product of series of complex and conservative processes, which include the air quality monitoring, preparation of emission inventory and control strategies delineation, and long-term compliance monitoring [11].…”