Standardized method for material flow data collection at city level
Description
In the excel file entitled by Method for data collection, the original information for the sectoral level data of material flows can be obtained following the statistical data sources presented in the template of data collection. The definitions of nine sectors (Internal Environment, Agriculture, Mining, Energy Conversion, Manufacturing, Recycling, Household, Construction, and Transportation) are described in Scopes of Sectors (Table S1). The templated spreadsheet (Table S2) was built to instruct the basic material flow data collection from statistical sources, and the last column in empty can help users to input their material flow data for their study area. Inventory of Conversion Factors (Table S3) lists all the conversion factors used in the sectoral material accounting at city level. The excel file of Data for the 16 Shandong cities in 2017 demonstrates the process of material flow accounting. First, raw data were acquired according to the data sources specified in the template. The blanks of some terms indicate the data cannot be accessed by statistical sources but need to be estimated based on the statistical data. In data preparation, some original data were simply calculated or repeated to further unify the physical units of original data by conversion factors. For example, as the original statistic for the number of vehicles are recorded by a specific year, not a variation between two years, so the simply calculations were done. Because the specific materials, like steel, aluminum are estimated by the added roads, pipelines and heat devices, some repetitive numbers appear in different terms for further estimations. Then, according to the conversion factors, the data with inconsistent units were converted into physical unit ton and sectoral material flows are presented in the material flow accounting. Furthermore, the total amounts of material input, material recycling, and waste disposal can be used to evaluate the CE indicators of the cities. In addition, following the pathways (e.g., f35 is the material flow from sector 3 mining to sector 5 manufacturing), the material flow dataset can be applied to construct the direct flow matrix, which is basic for the calculation of the integral flows in the ecological network.
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Data collection was divided into three sections (material input, material recycling, and waste disposal), nine sectors in the urban system, four categories of materials, and 155 items. For the input material, the fossil fuels mainly contain raw coal, crude oil, and natural gas. Industrial fuel products include gasoline, diesel, and fuel oil. Electricity and heat are converted into physical quantities of standard coal equivalents. Biomass contains farm crops, fruits, major forestry products, timber, animal husbandry production, and aquatic products. The metal ore and non-metallic minerals contain 28 categories. With regard to the sectoral material flows in construction, the consumptions of steel, cast iron, aluminum, cement, or gravel are estimated based on the growth of the infrastructure (floor space, roads, drainage pipelines, water supply pipelines, and heated devices). As to the sectoral material flows in households, the steel and aluminum consumptions are measured by the corresponding assumed component contents multiplying the numbers of increased refrigerators, washing machines, air conditioners, color TV sets, and computers. The steel and aluminum consumption in transportation are calculated by evaluating the amount of materials used in vehicles and trucks. For recycling material flows which are lack of the latest statistics, scrap rubber, vehicles, electrical and electronic waste products, scrap steel and non-ferrous metals, waste plastic, and paper were estimated on the basis of the provincial recycling data in period of 12th Five-year. In addition, the recycling rate of grain crops was adopted at an average level; kitchen waste, building and demolition waste were estimated by the capacities of the recycling treatment plants and the operation conditions of the plants; four kinds of waste for fuel, residual pressure, and heat for circulated use were also considered as materials recycling. For waste disposal, industrial solid wastes come from the city’s statistics; agricultural wastes were estimated by two parts: solid waste from aquacultures and unrecycled crop straws; construction and transportation wastes were measured by the generation minuses the recycling section, respectively. Based on the standardized methodology for MFA data collection, 16 cities of the Shandong Province were considered in the case study. Raw data from 2017 were collected from the statistical database, and unified material flow was converted using conversion factors. The ready-material flow datasets were used for two main purposes in this case. On one hand, the sectoral material flows were applied to construct the direct flow matrices which served to estimate integral flows in urban sectoral ecological networks. On the other hand, the processed datasets were also applied to evaluate the city’s CE indicators from the total amount of material input, recycling, and waste disposal.