Contamination Characteristics And Source Apportionment Of Fine Particles In Ningdong Coal Chemical Industrial Base Of The Energy Golden Triangle,China

As part of the Energy Golden Triangle in northwest China and the largest coal-to-liquids industry in the world,the Ningdong National Energy and Chemical Industrial Base（NECIB）released about 60%of sulfur dioxide（SO₂）in Ningxia Hui Autonomous Region where the NECIB locates.Air pollution has a serious impact on local air quality and residents’health,especially fine particulate matters which exert a more direct impact on the environment and human health.In this thesis,the results of extensive field and modeling investigations of the levels and emission source of fine particulate matter PM₁ and PM_2.5 in NECIB were reported,aiming at filling knowledge and regional gaps in fine particulate matter in national-scale coal chemical industries,providing scientific support to emission control strategies in NECIB.The thesis reports the chemical composition and source apportionment of PM₁and PM_2.5,collected using a medium flow and high flow atmospheric active samplers at two industrial sites Yinglite（YLT）and Baofeng（BF）.The field campaign was conducted during summer 2016（from July 3 to 30,2016）and winter 2017（from 22December 2016 to January 16,2017）,127 PM₁ samples and 131 PM_2.5 samples were collected.Concentrations of PM₁ and PM_2.5 and major chemical components in PM were analyzed,including water-soluble ions,carbonaceous aerosols（OC and EC）,and inorganic elements.The Positive Matrix Factorization（PMF）model,the ISORROPIAII thermodynamic equilibrium model,HYSPLIT backward trajectory model,OMI satellite detection data and WRF-Chem model were used to track possible sources and contributions of these chemical components to the formation of the two fine particles.The major results and findings are summarized below.The PM₁ concentrations in NECIB were 62.61⁷9.06μg·m^-3 in summer and88.35³18.02μg·m^-3 in winter.The PM_2.5.5 concentrations in NECIB were189.97³12.03μg·m^-3 in summer and 311.85⁵ 7.58μg·m^-3 in winter.The 12-hour sampling results showed that higher PM₁ levels were also monitored in the nighttime than that in the daytime.PM_2.5 concentration in the daytime was higher than that in the nighttime.PM₁ and PM_2.5 concentrations during the winter sampling period were higher than that in the summer.The PM_2.5 concentration of NECIB exceeded China’s PM_2.5 quality standard(75μg·m^-3)by 2-7 times,and measured PM_2.5 concentrations in the NECIB were significantly higher than majority of Chinese megacities and two local cities.PM₁ concentrations were factors of two to three higher than some megacities in North China.It can be seen that the pollution of fine particulate matter in the NECIB is serious.The PM₁/PM_2.5 ratios were<0.7,which are consistent with the ratios in the remote areas of western and northern China,and confirmed the credibility of the results of this study.For water-soluble inorganic ions concentrations,it was found that the^-has highest concentration among water-soluble inorganic ions in PM₁ and PM_2.5,followed by,,and^-at both sampling sites,respectively.The low concentratio n of indicates that biomass burning is not the main source of PM₁ and PM_2.5.5 in the NECIB.In winter samples,^-concentration was more than 6 times higher than that in summer.Since^-is one of the markers for combustion source,the increasing coal combustion due to domestic heating in winter could emerge as the main source of water-soluble ions.The simulation using the ISORROPIAII thermodynamic equilibrium model revealed that was mainly combined with^-and^-and presence in the form of NH₄NO₃ and NH₄Cl.Whereas,^-is mainly combined with to form CaSO₄.The carbonaceous aerosol concentrations and characteristics of fine particles in NECIB show that concentrations of OC and EC in summer at both sites were considerably lower than those in winter,and the concentrations of carbonaceous aerosol in YLT were lower than that at BF site.From the TCA（Total carbonaceous aerosol）contributed to PM₁ and PM_2.5 mass,it can be seen that the carbonaceous aerosol is an important component in PM₁ and PM_2.5.The OC/EC ratios in both PM₁and PM_2.5 in Ningdong,in general,laid between 1.1 and 2.0.Therefore,the origins of OC and EC at the YLT and BF sites could be traced back to emission sources of coal combustion and vehicle exhaust.The/EC ratios from 0.03 to 0.09 predict the emission from fossil fuel combustion.Results of inorganic elements concentrations and characteristics of fine particles in NECIB illustrate that the six metal elements with high concentrations in PM₁ and PM_2.5 in the NECIB were Al,Ca,Fe,Mg,K,and Na.The sum of their mass accounted for 95.8-98.7%of the total analyzed elemental mass,of which Ca has the highest concentration level.The EF values for Cr,Cu,Fe,Mg,Mn,Ni,and Ti in PM_2.5 at the two sampling sites were all below 1,indicating that these elements mainly were released from the soil.Cr and Cu in the summer sampling period,during which EF values were between 1 and 10 at both sampling sites,were likely associated with anthropogenic sources such as the vehicle or industrial emissions.However,the EF values for As and Pb in PM₁ and PM_2.5 at the two sampling sites were much greater than 10,suggesting that these two metal elements were emitted primarily from anthropogenic sources,such as coal combustion.Source apportionment results of fine particles in NECIB revealed that,by analyzing the chemical components in fine particles,the above three compnents（water-soluble inorganic ions,carbonaceous aerosols and inorganic elements）account for up to 60%of the mass of the fine particles,and the remaining 40%are unknown components.These results imply some missing sources in this large-scale coal chemical industry base.The PMF modeling source analysis identified the four main sources of fine particles.The first factor was associated with vehicle emissions（30.19%）,the second factor linked with soil dust（42.22%）,the third factor was related to biomass burning and waste incineration（5.06%）,and the fourth factor was featured by secondary inorganic aerosols and coal combustion（22.53%）.Among them,soil dust accounts for the highest proportion.WRF-Chem（Weather forecasting and atmospheric chemistry model）modeling results show that OC,EC and PM_2.5 mass and concentration were associated with local source emissions.Carbonaceous aerosols and PM_2.5 were primary compounds in Ningxia.Air pollution emissions from NECIB also affected surrounding cities.Modeled concentrations of OC and EC were consistent with sampled data,but the modeled mass of PM_2.5 was lower considerably than the measurements,again suggesting unknown sources of fine particles in this energy industrial base.In view of the rapid development of Ningdong large-scale coal chemical industry base in the past ten years,it is expected that coal chemical industry will continue to expand in northwestern China in coming years.The results of this study reveal the associations between local environmental pollution and large-scale coal chemical industry in northwestern China.However,the knowledge about the air emissions from coal-to-liquid industry is still lacking.Further studies are needed to investigate those potential missing emission sources from coal-chemical industry.