Study On The Temporal And Spatial Evolution Of Haze Pollution And Its Influencing Factors In The Loess Plateau From 1998 To 2017

In recent years,Haze Pollution has erupted in a large scale in China.Long-term exposure to high PM2.5contaminated air environment will cause irreversible damage to people's bodies and directly threaten people's health.PM2.5 is the primary pollutant of Haze Pollution.In 2013,the International Agency for Research on Cancer(IARC)hasincluded PM2.5 as a human careinogen.At present,China has taken many measures against PM2.5 pollution.In 2012,the Ministry of Environmental Protection newly revised the“Environmental Air Quality Standard(GB3095-2012)",,and added the PM2.5 concentration limit.In 2012,the State Council issued the "The 12th Five-Year Plan for Air Pollution Prevention and Control Plan in Key Areas'.The 'Twelfth Five-Year Plan”of the Air Pollution Prevention and Control Plan;In 2013,the Air Pollution Prevention and Control Action Plan was released.In 201 7,Premier Li Keqiang pointed out that the problem of haze pollution in northern China is unique in the world and needs to further study its formation mechanism.The Loess Plateau region,with complexed natural geographical environment,fragile ecological environment is located in the northwestern part of China.In the process of rapid industrialization and urbanization,Haze Pollution also exists.In January 2017,the monthly average concentration of PM2.5 in this region was as high as 91.62ug/m3,far higher than75ug/m3,the daily limit set by the ministry of environmental protection.In the process of comprehensively promoting the "Belt and Road”,the Rising Strategy in Central Region and the Western Development Program,this region will gather more people and industries.Therefore,to study the Haze Pollution problem of the Loess Plateau is of great practical significance for controlling the Haze Pollution and preventing it from happening.Therefore,Based on the definition Haze Pollution and clarified the standards of PM2.5 pollution at home and abroad,this paper took 341 counties in the Loess Plateau as the research units,to study the Haze Pollution of the Loess Plateau from two dimensions of time and space.In this paper,we firstly used the remote sensing inversion data of PM2.5 from 1998 to 2016 to discuss the temporal and spatial variation of haze pollution in the Loess Plateau.This paper also took the city as the research scale,describedtemporal and spatial variation characteristics of Haze Pollution of the Loess Plateau in 2017,and compared the characteristics of Haze Pollution in different research scales.Then,we selected four years in 2000,2005,2010 and 2015,using Hot-spot Analysis,Gravity Center Model and Trend Surface analysis methods,to study the spatial pattern evolution and agglomeration characteristics of Haze Pollution in the Loess Plateau by ArcGislo.2 software;we also described the Haze Pollution of the Loess Plateau in a year with the monthly average value of PM2.5 in 2017;Finally,12 factors are selected from the socio-economic and natural aspects of the year 2005 and 2015,using the Correlation Analysis Method and Geo-Detector,to analyze the effect of the single factor andtwofactors interaction on the spatial differentiation of Haze Pollution.We also discussed the change factors over time.The main conclusions were as follows:(1)From tempoal variation,from 1998 to 2016,the average annual of PM2.5Concentration of the Loess Plateau showed a fluctuating trend,it declined slowly from 2013 to 2016,annual declined by 1.71?g/m3.The average annual of PM2.5 concentration is between[15,35].According to the standards of the Ministry of Environmental Protection of China,the air quality of the Loess Plateau is up to standard,However,according to the WTO standard(10?g/m3),the air quality has not reached the standard for many years.(2)From the distinction of the spatial pattern,?the gravity center of the Haze Pollution in the Loess Plateau wasr datively stable from 1998 to 2016,mainly migrated in the three countries of Ganquan,Baota and Ansai of Yulin City.?From the perspective of spatial distribution,the Haze Pollution in the Loess Plateaushowed a stable pattern of“south was seriousand the north was light,in from 2000 to 2015.The area of Haze Pollution first expanded and then shrank.In 2005,the Haze Pollution of the Loess Plateauwas the most serious.The counties with light Haze Pollution weredistributed in the in the southeast of the the Loess Plateau,specifically distributed in the southern part of the plain area and southeast of the earth-rock mountain area The areas with normal air quality werealsoconcentrated in the valley plains and earth-rock mountains of the southeast of the Loess Plateau;the counties with good air quality weremainly distributed in the hilly and gully region,the gully region,the agricultural irrigation area in the westof the Loess Plateau;The eounties with excellent air quality are concentrated in the earth-rock mountain areas,agricultural irrigation areas and desert sand areas of the north..?From the perspective of spatial agglomeration,the PM2.5Concentration was positively correlated in space,the agglomeration characteristics wereobvious,and the featurewas continuously strengthened.The hotspot analysis showed that the HazePollution in the Loess Plateau hadformed a clear gradient patterm.From northwestto the southeast,it was cold point area,secondary cold point area,warm point area,sub-hot spot area,hot spot area,and warm point.From 2000 to 2015,the area of hotspots first increased and then narrowed.The area of cold spots gradually narrowed down.The hot spots formed a“two-core”distribution,with Fufeng County in Shanxi and Xin'an County in Henan as the center,with radius of about 80km and 56km respectively,weretwo high-value gathering areas;the cold spot area was distributed in the southern part of Inner Mongolia and the Qinghai Province in the west.(3)From the characteristics of changes during the year,in 2017,the monthly average of PM2.5Concentration showed a“U”sslaped curve changein the Loess Plateau.The seasonal characteristics are obvious and the pollution is more serious in winter.The cities spatial pattern is characterized by the distribution of "south heavyand north light",which is similarly with countiespattern in 2015.The districts with higher PM2.5 concentration are spatially coincident with the city where they are located,further indicating the spatial agglomeration characteristics of Haze Pollution.Significantly,in the counties with better air quality,the air quality of the city wherethey are located were not the best.(4)From the perspective of the effect of various factors,GDP,urbanization rate,population density,temperature,humidity and precipitation hada positive impact on the Haze Pollution in the region;The sunshine hours,wind speed,altitude and terrain relief,hada negative impact on the degree of smog pollution in this area.The effect of the proportion of the second production and per capita GDP is not significant.(5)From the effect of various types of factors on the spatial differentiation of Haze Pollution,the spatial differentiation characteristics of haze pollution in the Loess Plateau werenot determined by a single influencing factor.However they wereaffected by both socio-economic and natural factors.In the Loess Plateau,at different times,the effectof factors were different on the spatial differentiation of Haze Pollution,but the effect of natural factors was greater than the socio-economic factors onHaze Pollution.In 2005,from warm to weak,the explanatory factors of the spatial distributionof smog pollution in theLoess Plateau were Temperature>Altitude>SunlightHours>PopulationDensity>RelativeHumidity>Precipitat ion>WindSpeed>Terrain Relief>GDP>Urbanization rate>PerCapita GDP>The proportion of the Second Production;In 2015,the result wasAltitude>Temperature>Precipitation>Sunshine Hours>Population Density>Relative Humidity>Wind Speed>Terrain Relief>GDP>The proportion of Secondary Production>Per Capita GDP>Rrbanization Rate.In terms of social and economic factors,the effect of interaction of two factors was greater than the singlefactors.For single influencing factors,population density had always been the main factor in affecting the spatial differentiation of Haze Pollution in the Loess Plateau.In terms of interaction,the interaction between population density and urbanization rate,GDP hada greater impact.As time goes by,the interaction effect of two social-economic factors was more and more important in explaning spatial differentiation ofmaze Pollution in the Loess Plateau.In terms of natural factors,the effect of interaction of two factors is also greater than the singlefactors.In terms of single influencing factors,altitude and temperature werethe main natural factors affecting the spatial differentiation of haze pollution in the Loess Plateau,and the impact wasincreasing.In terms of interaction,the interaction of temperature and topographic relief hadthe greatest explanatory power for Haze Pollutionin the Loess Plateau.(6)From the factors in the city scale,in 2017,the relationship between HazePollution and the distribution of natural topographic units was significantin the Loess Plateau.Cities in the plains and earth-rock areas,their Haze Pollutionwere the most serious;Cities in the hilly and gully areas,their Haze pollution wereserious,and the The Haze Pollution of Cities was relatively lightin the desert sand and agricultural and forestry irrigated areas.The PM2.Z concentration had significant positive correlation with GDP and population density,and had negativecorrelation with the wind speed.