Characteristics of Particulate Carbon in Precipitation during the Rainy Season in Xiamen Island, China

Abstract

Abstract:Measuring wet deposition of organic carbon (OC) and elemental carbon (EC) aerosol is crucial for the understanding of their circulation and climate effect. To further understand the wet deposition of particulate carbon (OC and EC), precipitation samples were collected from April to August 2014 on Xiamen Island in China. EC and water insoluble organic carbon (WIOC) concentrations were analyzed using a thermal optical method to investigate temporal variations and wet deposition fluxes. The average EC and WIOC concentrations were 7.3 µgC·L −1 and 495.3 µgC·L −1 , respectively, which are both comparable to the results reported in European areas. EC and WIOC concentrations were higher in spring than in summer. Higher EC concentrations were found in April, which were probably associated with the transport of air masses from northern continental areas. Higher WIOC concentrations were found in May and were mainly attributed to air masses from the South China Sea. Lower concentrations of EC and WIOC in the summer were primarily due to the clean air masses transported from the ocean. The wet deposition flux was calculated as the product of concentration and precipitation amount. Average wet deposition fluxes of EC and WIOC were estimated to be 0.6 mgC·m −2 ·month −1 and 36.7 mgC·m −2 ·month −1 , respectively. Wet deposition fluxes of EC and WIOC exhibited similar concentration trends. The largest flux in EC wet deposition occurred in April (1.8 mgC·m −2 ·month −1 ), while the largest flux in WIOC wet deposition occurred in May (63.1 mgC·m −2 ·month −1 ).

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

“…Unlike in-cloud scavenging, studies of total wet scavenging were generally fulfilled with offline approaches, which usually require pretreatments, rendering a lower time resolution. BC in rainwater samples are quantified with various methods, including thermal-optical technology (TOT) [69,70], SP2 [58], and ultraviolet-visible spectrophotometer (UV/VIS) [71]. Equation 2is also compatible when studying the scavenging rate constant (r) in total wet scavenging by rainfall [61,72,73].…”

Characteristics of Atmospheric Inorganic Nitrogen Wet Deposition in Coastal Urban Areas of Xiamen, China

“…The concentrations of NO 3 − -N and NH 4 + -N in this region were both high in spring, but low in summer. Their trends of change were the same as those of WIOC (water-insoluble organic carbon) and EC (element carbon) due to the clean air masses from the ocean [23]. In fact, the great variability in sea salt aerosols, especially during the rainy season, was largely dependent on precipitation due to the wet deposition removal effect [29].…”

“…During the sampling period, the daily precipitation ranged from 0.1 mm to a maximum of 80.9 mm. The maximum (80.9 mm) occurred on 23 May 2014 due to the heavy rains driven by the southwest low-level jet stream, which provides a large amount of moisture and unstable energy [23]. Typhoon Hagibis on 16 June 2014 and Typhoon Matmo on 23 July 2014 also brought strong single-day precipitation events to Xiamen, coinciding with the values of 57.91 mm and 39.12 mm, respectively.…”

“…The precipitation in May was mainly affected by the confluence of heating and cooling flows, and the precipitation in summer (June to August) was mainly controlled by oceanic air masses. precipitation events from April to August [23] .…”