In terms of the midstream, besides pipeline laying and site selection, we focus on monitoring the system, including leak detection, quality management of engineering materials, and risk identification and management. In the upstream stage, especially hydraulic fracturing activity, we suggest strengthening environmental assessment management, improving policy standards, creating a water quality monitoring plan, and promoting the innovation of key technologies. Thus, this article puts forward some policy recommendations for different stages from exploitation to utilization. In the downstream combustion and utilization stage, the risk to environment is less than other energy sources, although there are some greenhouse gas effects and water pollution issues. During the midstream storage and transportation stage, methane leakage is the biggest environmental risk. It is found that, during upstream exploitation, hydraulic fracturing has the worst environmental impact. Firstly, this article identifies various environmental risks and benefits of natural gas along the entire industry chain from upstream exploitation and midstream transportation to downstream utilization. However, there remain environmental risks at different stages in the entire process from exploitation to utilization. In response to climate change and energy transition, natural gas has been rapidly developed as a relatively low-carbon energy source by many countries. 2National Laboratory of Biomacromolecules, University of Chinese Academy of Social Sciences, Beijing, China.1School of Economics and Management, Beijing Jiaotong University, Beijing, China.The framework for using receptor models to solve air quality problems consists of: (1) formulating a conceptual model (2) identifying potential sources (3) characterizing source emissions (4) obtaining and analyzing ambient PM samples for major components and source markers (5) confirming source types with multivariate receptor models (6) quantifying source contributions with the chemical mass balance (7) estimating profile changes and the limiting precursor gases for secondary aerosols and (8) reconciling receptor modeling results with source models, emissions inventories, and receptor data analyses.Jiaxin Fu 1*, Yingqi Liu 1 and FeiHong Sun 2 Measurements from existing networks can be used to form conceptual models that allow the needed monitoring network to be optimized.

Compliance monitoring networks are not usually designed to obtain data for the observables, locations, and time periods that allow receptor models to be applied.

While elements, ions, and carbons were often used to apportion TSP, PM 10, and PM 2.5 among many source types, many of these components have been reduced in source emissions such that more complex measurements of carbon fractions, specific organic compounds, single particle characteristics, and isotopic abundances now need to be measured in source and receptor samples. Enrichment factor, chemical mass balance, multiple linear regression, eigenvector, edge detection, neural network, aerosol evolution, and aerosol equilibrium models have all been used to solve particulate air quality problems, and more than 500 citations of their theory and application document these uses.

Receptor models complement source models that estimate concentrations from emissions inventories and transport meteorology. Receptor models infer contributions from particulate matter (PM) source types using multivariate measurements of particle chemical and physical properties.

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