Spatiotemporal Variation and Chemical Fingerprints of Marine Fine Particles (PM2.5) at the Matsu Islands in Northern Taiwan Strait

Abstract A VHF pulsed radar system was set up on the Taoyuan County seashore (24°57′58″N, 121°00′30″E; Taiwan) to observe the sea surface in the northern Taiwan Strait for the first time. The radar used a four-element, vertically polarized Yagi antenna to transmit the 52-MHz radar wave. The receiving linear array consists of four vertical dipole antennas that were located 3 m apart and attached with four independent and identical receivers. With the multichannel echoes, the direction of arrival (DOA) of the radar echoes were determined by using an optimization beamforming approach—the Capon method. Echo intensity was observed to vary principally in semidiurnal oscillation, which matched well the time series of tide gauge measurements and sea level simulations. In addition, the oscillatory characteristics of Doppler/radial velocity of the VHF radar were generally consistent with that of the HF coastal ocean dynamics applications radar (CODAR) nearby. Nevertheless, the contributions of various tidal modes to the parameters of DOA, echo intensity, radial velocity, and spectral width, varied with the range and time period (e.g., neap or spring tides). For example, the semidiurnal tides governed the variation in the echo center only in the range interval between ~15 and ~25 km from the seashore but dominated other parameters throughout the detectable range. Correlations and phase relationships between these parameters were diverse; they varied with time and had dramatic changes at around the distances of 3 and 10 km. Possible causes of these features were discussed, including sea surface wind, nearshore current, sea level height, and bathymetric effect.

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Hydrocarbons in the surface sediments of northern Taiwan Strait

Deep Sea Research Part B Oceanographic Literature Review ◽

10.1016/0198-0254(79)90688-5 ◽

1979 ◽

Vol 26 (12) ◽

pp. 772

Keyword(s):

Surface Sediments ◽

Taiwan Strait ◽

Northern Taiwan

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Size-segregated particle number and mass concentrations from different emission sources in urban Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-12721-2020 ◽

2020 ◽

Vol 20 (21) ◽

pp. 12721-12740

Author(s):

Jing Cai ◽

Biwu Chu ◽

Lei Yao ◽

Chao Yan ◽

Liine M. Heikkinen ◽

...

Keyword(s):

Particle Size ◽

Particulate Matter ◽

Source Apportionment ◽

Particle Number ◽

Fine Particles ◽

Size Distributions ◽

Vehicular Emissions ◽

Particle Size Distributions ◽

Chemical Fingerprints ◽

Mass Concentrations

Abstract. Although secondary particulate matter is reported to be the main contributor of PM2.5 during haze in Chinese megacities, primary particle emissions also affect particle concentrations. In order to improve estimates of the contribution of primary sources to the particle number and mass concentrations, we performed source apportionment analyses using both chemical fingerprints and particle size distributions measured at the same site in urban Beijing from April to July 2018. Both methods resolved factors related to primary emissions, including vehicular emissions and cooking emissions, which together make up 76 % and 24 % of total particle number and organic aerosol (OA) mass, respectively. Similar source types, including particles related to vehicular emissions (1.6±1.1 µg m−3; 2.4±1.8×103 cm−3 and 5.5±2.8×103 cm−3 for two traffic-related components), cooking emissions (2.6±1.9 µg m−3 and 5.5±3.3×103 cm−3) and secondary aerosols (51±41 µg m−3 and 4.2±3.0×103 cm−3), were resolved by both methods. Converted mass concentrations from particle size distributions components were comparable with those from chemical fingerprints. Size distribution source apportionment separated vehicular emissions into a component with a mode diameter of 20 nm (“traffic-ultrafine”) and a component with a mode diameter of 100 nm (“traffic-fine”). Consistent with similar day- and nighttime diesel vehicle PM2.5 emissions estimated for the Beijing area, traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor resulting from source apportionment using chemical fingerprints) and black carbon (BC) showed similar diurnal patterns, with higher concentrations during the night and morning than during the afternoon when the boundary layer is higher. Traffic-ultrafine particles showed the highest concentrations during the rush-hour period, suggesting a prominent role of local gasoline vehicle emissions. In the absence of new particle formation, our results show that vehicular-related emissions (14 % and 30 % for ultrafine and fine particles, respectively) and cooking-activity-related emissions (32 %) dominate the particle number concentration, while secondary particulate matter (over 80 %) governs PM2.5 mass during the non-heating season in Beijing.

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