The spatial-temporal pattern and influencing factors of negative air ions in urban forests, Shanghai, China

Abstract

Negative air ions are natural components of the air we breathe. Forests are the main continuous natural source of negative air ions (NAI). The spatio-temporal patterns of negative air ions were explored in Shanghai, based on monthly monitoring in 15 parks from March 2009 to February 2010. In each park, sampling sites were selected in forests and open spaces. The annual variation in negative air ion concentrations (NAIC) showed peak values from June to October and minimum values from December to January. NAIC were highest in summer and autumn, intermediate in spring, and lowest in winter. During spring and summer, NAIC in open spaces were significantly higher in rural areas than those in suburban areas. However, there were no significant differences in NAIC at forest sites among seasons. For open spaces, total suspended particles (TSP) were the dominant determining factor of NAIC in summer, and air temperature and air humidity were the dominant determining factors of NAIC in spring, which were tightly correlated with Shanghai'songoing urbanization and its impacts on the environment. It is suggested that urbanization could induce variation in NAIC along the urban-rural gradient, but that may not change the temporal variation pattern. Furthermore, the effects of urbanization on NAIC were limited in non-vegetated or less-vegetated sites, such as open spaces, but not in well-vegetated areas, such as urban forests. Therefore, we suggest that urban greening, especially urban forest, has significant resistance to the

What Causal Drivers Influence Carbon Storage in Shanghai, China’s Urban and Peri-Urban Forests?

“…The transect passes through five administrative districts: the city center of Shanghai, Pudong new area, Minhang, Fengxian, and Jinshan; and accounts for all urban to peri-urban land cover types found in the region (Figure 1). The study area has a typical subtropical monsoon climate and a distinct seasonal temperature pattern with a mean annual temperature of 18 • C and a mean annual rainfall of approximately 1158 mm [32].…”

“…The transect passes through five administrative districts: the city center of Shanghai, Pudong new area, Minhang, Fengxian, and Jinshan; and accounts for all urban to periurban land cover types found in the region (Figure 1). The study area has a typical subtropical monsoon climate and a distinct seasonal temperature pattern with a mean annual temperature of 18 °C and a mean annual rainfall of approximately 1158 mm [32]. Shanghai has a population of 23 million, or 3800 inhabitants per km 2 , is located on an alluvial plain at the outlet of the Yangtze River, and its urbanization processes are typical of modern Chinese cities [33].…”

Effects of Urban Green Belts on the Air Temperature, Humidity and Air Quality

“…In addition, green belts play an important role in improving air quality (Islam et al 2012). The concentration of negative air ions and bacteria rates are important indices for evaluating air quality (Tikhonov et al 2004) and play an important role in improving environmental indicators, but related research has mainly focused on forest vegetation communities (Liang et al 2014).…”

Application of a novel microalgae‐film based air purifier to improve air quality through oxygen production and fine particulates removal

“…First, negative air ions generated by photosynthesis of microalgae cells may contribute to the air purification by neutralizing the surface charge on fine particulates and accelerating their coagulation. In the negative ions hypothesis, concentration of negative air ions, partly determined by photosynthesis, directly impacts the removal of fine particulates . Second, positively charged airborne fine particulates might be captured by the negatively charged surface of microalgae .…”

“…In the negative ions hypothesis, concentration of negative air ions, partly determined by photosynthesis, directly impacts the removal of fine particulates. 13,14 Second, positively charged airborne fine particulates might be captured by the negatively charged surface of microalgae. 15 Since the ionization of functional groups (hydroxyl, carboxyl, sulfhydryl, etc.)…”