Forests 2022 , 13 , 1856
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In Equation (7), C I is the total CO 2 emission of paper raw material import transporta- tion (10 6 t), F p and F w are the import volume of pulp and waste paper respectively (10 6 t), and the sum of both is the total import volume of paper raw material (10 6 t), D α and D β are the water transportation distance between the largest port of the α th pulp exporting country and the β th waste paper exporting country and Shanghai port respectively (km), and ϕ 1 is theCO 2 emission coefficient of waterway transportation mode (tCO 2 /10 6 t.km). Since it is difficult to obtain specific data on the volume of pulp and waste paper transported by the main paper and paperboard producing provinces from each major port, D N is the average distance (km) of the actual distance between all major ports to the provincial capitals of the main paper and paperboard-producing provinces, and based on the average distance, we set that the domestic transport process is dominated by rail transport, and ϕ 2 is theCO 2 emission factor of the rail transport mode. (2) CO 2 emission accounting method for domestic waste paper recycling and transporta- tion process Paper and paper products are involved in almost every aspect of everyone’s life, and within the Chinese region, the consumer market is nationwide, with waste paper generally originating from China’s 31 provinces, autonomous regions, and municipalities (Hong Kong, Macau, and Taiwan of China are not counted). The recovered waste paper is transported to 16 paper and paperboard-producing provinces with complicated and irregular transportation routes. Therefore, this paper sets 31 provinces, autonomous regions, and municipalities directly under the Central Government to follow the principle of proximity and uniqueness, i.e., only transport to the nearest major paper and paperboard- producing province. Taking the actual distance between these two provincial capitals as the transportation distance of waste paper recycling, and the transportation mode is also mainly railroad transportation, the CO 2 emission accounting formula of the domestic waste paper recycling transportation process is as follows. C z = F w × D w × ϕ 2 (8) In Equation (8), C z isCO 2 emissions from domestic waste paper recycling transporta- tion (10 6 t). Since specific data on the amount of waste paper shipped to the main paper and paperboard production sites in each province and city are not available, F w is the total amount of waste paper recovered (10 6 t) and, D w is the average distance (km) between the source of all recovered waste paper and the provincial capitals of the main paper and paperboard production sites. 2.2.4. Accounting for CO 2 Emissions in the Transportation Stage In order to ensure the consistency of methods and data sets in the time series and minimize accounting errors, the first-order attenuation method is used to estimate the CO 2 emissions from waste paper open landfill and incineration. (1) Open landfill Open-air landfills mainly release CH 4 , and the accounting converts CH 4 emissions intoCO 2 emissions, with the following accounting formula. C J = MSW m × DOC × DOC f × MCF × F × 16 12 (9)
C d = MSW m × DOC × DOC f × ( 1 − MCF × F ) × 44 12
(10)
In Equations (9) and (10), MSW m is the volume of waste paper landfill (10 6 t), DOC is the proportion of decomposable organic carbon (%) (how many kg of carbon per kg of landfill waste paper), DOC f is the proportion of decomposable DOC (%), MCF is theCH 4 correction factor for aerobic decomposition (%), F is the proportion of CH 4 in landfill gas (%), 16 12 isCH 4 /C molecular weight ratio, and 44 12 is theCO 2 /C molecular weight ratio.
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