Eco-district Environmental Performance Assessment And Road Freight Vehicles Analysis Of Emission Characteristics

In recent years,with the vigorous development of highway construction and transportation and logistics industry,regional economic benefits have improved while environmental pollution problems have also emerged,especially air pollution caused by freight transportation process.Ecological regions generally have the characteristics of fragile internal ecological environment and low natural recovery capacity,and it is difficult to carry excessive air pollution.Therefore,reducing exhaust emissions in the freight process has become the key to achieving environmental protection and economic development.Accurate understanding of motor vehicle emissions can help reduce regional traffic atmospheric pollution.At present,the impact of relevant research on air pollution is mostly analyzed from a qualitative perspective,while the research on truck exhaust emissions mainly focuses on urban scope,and less attention is paid to ecological areas.Based on this,taking the Qilian Mountain Ecological Region as an example,the research is carried out from two aspects:regional environmental performance and freight vehicle emission characteristics,and the main content is divided into the following two parts.The first part evaluated the environmental performance of the Qilian Mountain ecological region based on the non-expected SBM model from a macro perspective to quantitatively analyze the impact of air pollutants on the environment.Firstly,the relevant principles and frameworks of the non-expected SBM model were sorted out,and the environmental performance evaluation index system was established based on the relevant literature and research needs.Secondly,an evaluation model was constructed,and the environmental performance and undesired output relaxation variable values of Qilian Mountain Ecological Region in 2012～2020 were calculated by Dearun software,and the results showed that the environmental performance of Qilian Mountain Ecological Functional Area in 2012～2020 was in an increasing trend,which was basically consistent with the relevant research results.In addition,the relaxation variables of undesired output in the Qilian Mountains in 2012～2020 were all positive.Among them,the relaxation variable of undesired output SO₂ continued to decline,while the relaxation variable value of non-expected output NO_x showed an upward trend in 2012～2019,and the relaxation variable value of undesired output soot increased sharply in 2019～2020.Finally,based on the research results,two conclusions were concluded:First,the environmental performance of the Qilian Mountain ecological region has been increasing in recent years,but it has not reached the effectiveness of DEA,and there was some room for improvement from the production frontier.Second,the emission of air pollutants in the Qilian Mountains ecological region,especially NO_x and soot,still needed to be controlled to achieve the best.The second part studied the emission characteristics of freight vehicles in the Qilian Mountains ecological region based on the MOVES model from a microscopic perspective,and then formulates targeted freight vehicle control measures.Firstly,through preliminary research,the G30 Yong Shan section of the Qilian Mountain Ecological Zone was determined as the research object,and field data collection was carried out.Secondly,the MOVES model was locally corrected,and the average daily emissions and emission factors of CO,NO_x,SO₂and particulate matter（PM2.5,PM10）of freight vehicles in this section were obtained after substituting the vehicle information data.The results showed that NO_x emissions were higher and CO emissions were lower in spring compared to winter.There were no significant changes in SO₂,PM2.5 and PM10 emissions.In addition,the influence of road slope,average speed and load on various pollutant emission factors was analyzed under single-factor change and multi-factor change.The results showed that the CO emissions of medium and heavy goods vehicles were more sensitive to slope changes from-5%to-3%,and the sensitivity was reduced when the speed changed.NO_x emission in the[75,80)speed range was more sensitive to slope change from-1%to 0%.SO₂,PM2.5 and PM10 emissions were minimized on the flat road at a constant speed,and when the speed changed,their emissions increased with the increase of slope.In downhill sections,NO_x and CO emissions were greatest under no load.On uphill roads,NO_x and CO emissions were greatest when fully loaded.However,there was no significant change in SO₂,PM2.5 and PM10 emissions in the uphill and downhill sections.Finally,four points were concluded:First,the seasonal emission characteristics of CO and NO_x pollutants in the highway section of Qilian Mountain Ecological Region were obvious.Second,the road slope had a significant impact on the emission of five pollutants of heavy vehicles in the highway section of the Qilian Mountain Ecological Zone,and the degree of impact was different under different speeds.Third,the average speed of vehicles had a significant impact on the emission of five pollutants of heavy vehicles in the highway section of the Qilian Mountain Ecological Zone.Fourth,on the surface with a slope of 0%,the vehicle load had no significant impact on the emission of five pollutants of heavy vehicles in the highway section of the Qilian Mountain Ecological Zone,and when there was a slope change,the load would have a significant impact on CO and NO_x emissions.The above research conclusions will provide reference for the environmental management policy and the setting of road freight vehicle control measures in the Qilian Mountain Ecological Zone.