2020同步年報

Environmental and Earth Science 065 P M 2.5 is considered a health high-risk factor in the components of air pollutants, which can directly enter the respiratory system, leading to 4.2 million deaths per year. An air-quality index is currently used to define the air quality, which is predicted using the level of six atmospheric pollutants, including PM 2.5 , PM 10 , SO 2 , NO 2 , CO, and O 3 . The PM 2.5 sampling period was from March 2016 to February 2017 in the Yangtze River Delta (YRD) and Pearl River Delta (PRD) regions. One 24-hour PM 2.5 sample was collected weekly in all locations of these YRD and PRD regions; monthly sampling was undertaken for Lishui in the YRD region. PM 2.5 was indicated to be associated with toxic trace metalloids and organics ( e.g ., polycyclic aromatic hydrocarbons), significantly increasing health risks. The accumulated evidence indicates that transition metals in fine particles are closely associated with oxidative DNA damage despite their small mass relative to that of other components. PM 2.5 sam- ples were analyzed, including organic carbon, elemental carbon (EC), water-soluble ions, total metalloids, and bio-accessible metalloids. The health risks of inhalation of the sampling sites caused by PM 2.5 -associated metal(loid)s were predicted on a basis of an annual average of bio-accessible concentrations of metallic elements Fe(III), Mn(II), V(V), Ni(II), Cr(III), As(V), Cu(II), Pb(II), Zn(II) and Cd(II), focusing on both the carcinogenic risks and non-carcinogenic risks for adult residents. Regarding the effect po- tency of various metals, the benchmark from the USA Environmental Protection Agency (USEPA), correlated with the use of the inhalation unit risk (IUR) and reference concentration (RfCi) of metals in their most toxic form is a common practice in risk Fig. 1 : Toxicity potency of metal ions about their speciation. (a) Correlation between effect concentration (EC IR1.5 ) for reactive-oxygen-species (ROS) induction (M) of various metal ions and IUR (mg/m 3 ) -1 , as well as the reference concentration (mg/m 3 ) via inhalation (RfC i ) of various metals specified in the documents of USEPA (2018) and other national standards. The EC IR1.5 data of the metal ions herein are based on particular kinds of speciation; (b) presents the dominant speciation of arsenic in three PM 2.5 samples with large concentrations of As(III) and As(V) in the semirural-industrial site (Heshan) in PRD and one in the suburban-industrial site (Pukou) in YRD, illustrated by XANES spectra (black solid line). The red dotted lines represent the LCF results. [Reproduced from Ref. 1] assessments, shown in Fig. 1(a) . Arsenic shows great dis- parities in toxicity between various forms; inorganic As(V) was observed to be the predominant species, accounting for over 80% of the total arsenic content of airborne parti- cles in urban areas. To explore the formation of molecular species and total arsenic ion (As(III) and As(V)) in a PM 2.5 Health Risk-Oriented Source Apportionment of PM 2.5 -Associated Trace Metals Particulate matter (PM 2.5 ) comprises suspended particulates of diameter 2.5 µm or less in aerody- namic diameter in the atmosphere. Most emission sources of PM 2.5 are contributed from human activity, seriously impacting human health by direct inhalation. Xiangdong Li et al. investigated the PM 2.5 -associated metals in two regions of high activity, YRD and PRD regions in China. The re- sulting carcinogenic risk that these elements posed was greater in YRD than in PRD. An increased contribution from the emissions of industrial activity was observed in the YRD region, but both traffic and non-traffic emissions from the burning of coal, waste and biomass were dominant sources of cancer and non-cancer risks posed by metals in both regions.