Impacts of Migration on Urban Environmental Pollutant Emissions in China: A Comparative Perspective

In recent years,researchers have devoted considerable attention to identifying the causes of urban environmental pollution.To determine whether migrant populations significantly affect urban environments,we examined the relationship between urban environmental pollutant emissions and migrant populations at the prefectural level using data obtained for 90 Chinese cities evidencing net in-migration.By dividing the permanent populations of these cities into natives and migrants in relation to the population structure,we constructed an improved Stochastic Impacts by Regression on Population,Affluence and Technology model(STIRPAT)that included not only environmental pollutant emission variables but also variables on the cities’attributes.We subsequently conducted detailed analyses of the results of the models to assess the impacts of natives and migrants on environmental pollutant emissions.The main findings of our study were as follows:1)Migrant populations have significant impacts on environmental emissions both in terms of their size and concentration.Specifically,migrant populations have negative impacts on Air Quality Index(AQI)as well as PM2.5 emissions and positive impacts on emissions of NO2 and CO2.2)The impacts of migrant populations on urban environmental pollutant emissions were 8 to 30 times weaker than that of local populations.3)Urban environmental pollutant emissions in different cities differ significantly according to variations in the industrial structures,public transportation facilities,and population densities.

Toward to agricultural green development by multi-objective zoning and nitrogen nutrient management:a case study in the Baiyangdian Basin,China

Although China has achieved great advancements toward national food security,the country is still confronted with a range of challenges,including natural resource stress,imbalanced diets and environmental pollution.Optimized management of crop–livestock systems is the key measure to realize agricultural green transformation.However,optimized management of crop–livestock systems that use multi-objective zoning is lacking.This study employed a multi-objective zoning management approach to comprehensively analyze four indicators:ammonia volatilization,nitrogen surplus,soil carrying capacity and ecological red line area.With its significant ecological integrity and a strong emphasis on sustainability,the Baiyangdian Basin serves as a unique and suitable test case for conducting analyses on multi-objective nutrient optimization management,with the aim to facilitate the agricultural green transformation.This study finds that less than 8%of the area in the Baiyangdian Basin meet the acceptable environmental indicator standard,whereas around 50%of the area that had both nitrogen surplus and ammonia volatilization exceeded the threshold.Implementation of unified management,that is,the same management technique across the study areas,could result in an increase of areas meeting environmental indicator thresholds to 21.1%.This project developed a novel multi-indicator partition optimization method,in which distinct measures are tailored for different areas to satisfy multiple environmental indicators.Implementation of this method,could potentially bring more than 50%area below the threshold,and areas with ammonia emissions and nitrogen surplus could be reduced to 15.8%.The multi-indicators partition optimization method represents a more advanced and efficiency-oriented management approach when compared to unified management.This approach could be regarded as the best available option to help China achieve agricultural transformation to improve efficient production and reduce environmental pollution.It is recommended that current policies aimed at nutrient management toward sustainable agricultural development should shift toward the application of multi-indicators partition optimization.

Regional inequality, spatial spillover effects, and the factors influencing city-level energy-related carbon emissions in China

Data show that carbon emissions are increasing due to human energy consumption associated with economic development. As a result, a great deal of attention has been focused on efforts to reduce this growth in carbon emissions as well as to formulate policies to address and mitigate climate change. Although the majority of previous studies have explored the driving forces underlying Chinese carbon emissions, few have been carried out at the city-level because of the limited availability of relevant energy consumption statistics. Here, we utilize spatial autocorrelation, Markov-chain transitional matrices, a dynamic panel model, and system generalized distance estimation(Sys-GMM) to empirically evaluate the key determinants of carbon emissions at the city-level based on Chinese remote sensing data collected between 1992 and 2013. We also use these data to discuss observed spatial spillover effects taking into account spatiotemporal lag and a range of different geographical and economic weighting matrices. The results of this study suggest that regional discrepancies in city-level carbon emissions have decreased over time, which are consistent with a marked spatial spillover effect, and a ‘club' agglomeration of high-emissions. The evolution of these patterns also shows obvious path dependence, while the results of panel data analysis reveal the presence of a significant U-shaped relationship between carbon emissions and per capita GDP. Data also show that per capita carbon emissions have increased in concert with economic growth in most cities, and that a high-proportion of secondary industry and extensive investment growth have also exerted significant positive effects on city-level carbon emissions across China. In contrast, rapid population agglomeration, improvements in technology, increasing trade openness, and the accessibility and density of roads have all played a role in inhibiting carbon emissions. Thus, in order to reduce emissions, the Chinese government should legislate to inhibit the effects of factors that promote the release of carbon while at the same time acting to encourage those that mitigate this process. On the basis of the analysis presented in this study, we argue that optimizing industrial structures, streamlining extensive investment, increasing the level of technology, and improving road accessibility are all effective approaches to increase energy savings and reduce carbon emissions across China.

Factors influencing polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emissions and control in major industrial sectors: Case evidence from Shandong Province, China

Analyzing determinants that influence polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran（PCDD/F） emissions is helpful for decision-makers to find effective and efficient ways to mitigate PCDD/F emissions. The PCDD/F emissions and the contributions of the scale effect, structure effect and technology effect to emissions from eight main industrial sectors in2006, 2008 and 2010 in Shandong Province, were calculated in this article. Total PCDD/F emissions in Shandong increased by 52.8% in 2008（614.1 g I-TEQ） and 49.7% in 2010（601.8 g I-TEQ） based on 2006（401.9 g I-TEQ）. According to the decomposition method, the largest influencing factor on PCDD/F emission changes was the composition effect（contributed 43.4%in 2008 and 120.6% in 2010 based on 2006）, which was also an emission-increasing factor.In this case, the present industrial restructuring policy should be adjusted to control the proportion of production capacities with high emission factors, such as iron ore sintering and steelmaking and the secondary non-ferrous metal sector. The scale effect increased the emissions in 2008（contributed 21.9%） and decreased the emissions in 2010（contributed-28.0%）. However, as a source control measure, the excess capacity control policy indeed had a significant role in emission reduction. The main reason for the technology effect（contributed 34.7% in 2008 and 7.4% in 2010 based on 2006） having an emission-increasing role was the weakness in implementing policies for restricting industries with outdated facilities. Some specific suggestions were proposed on PCDD/F reduction for local administrators at the end.

The presence and partitioning behavior of flame retardants in waste,leachate,and air particles from Norwegian waste-handling facilities

Flame retardants in commercial products eventually make their way into the waste stream.Herein the presence of flame retardants in Norwegian landfills, incineration facilities and recycling sorting/defragmenting facilities is investigated. These facilities handled waste electrical and electronic equipment（WEEE）, vehicles, digestate, glass, combustibles, bottom ash and fly ash. The flame retardants considered included polybrominated diphenyl ethers（∑BDE-10） as well as dechlorane plus, polybrominated biphenyls, hexabromobenzene,pentabromotoluene and pentabromoethylbenzene（collectively referred to as ∑FR-7）. Plastic,WEEE and vehicles contained the largest amount of flame retardants（∑BDE-10： 45,000–210,000 μg/kg; ∑FR-7： 300–13,000 μg/kg）. It was hypothesized leachate and air concentrations from facilities that sort/defragment WEEE and vehicles would be the highest. This was supported for total air phase concentrations（∑BDE-10： 9000–195,000 pg/m^3 WEEE/vehicle facilities, 80–900 pg/m^3 in incineration/sorting and landfill sites）, but not for water leachate concentrations（e.g., ∑BDE-10： 15–3500 ng/L in WEEE/Vehicle facilities and 1–250 ng/L in landfill sites）. Landfill leachate exhibited similar concentrations as WEEE/vehicle sorting and defragmenting facility leachate. To better account for concentrations in leachates at the different facilities, waste-water partitioning coefficients, Kwastewere measured（for the first time to our knowledge for flame retardants）. WEEE and plastic waste had elevated Kwastecompared to other wastes, likely because flame retardants are directly added to these materials. The results of this study have implications for the development of strategies to reduce exposure and environmental emissions of flame retardants in waste and recycled products through improved waste management practices.