迈向郊区社会:中国郊区研究的梳理、反思与展望

城乡中国时代,郊区既是城市经济发展的重要布局空间,也是打造新型城乡关系、实现乡村振兴、探索共同富裕的关键场域,由此引起了研究者们的高度关注。对中国郊区研究进行阶段性回顾与反思,能为广大城市郊区在新发展阶段探索更高质量的发展提供理论准备。既有研究主要聚焦于对郊区的概念确定、经济发展机制、乡村发展与振兴、社会治理、生活模式、区域形态及类型比较这六个核心议题。研究发现,尽管各学科从不同侧面对中国郊区进行了不同程度的揭示,但研究者们都无法忽视的且具有中国特色的经验事实是,中国郊区在体制粘连性、空间融合性与文化一体性的综合作用下形成了整体性特征。基于此,本文提出了“郊区社会”的概念,主张建立研究中国郊区的整体性视角,并初步对接下来的郊区社会研究做了方向性思考,以期为中国城市与郊区研究的本土化做一些理论努力。

西方郊区化的人文理念特征与影响及对乡村振兴战略背景下中国郊区建设的启示

本文分析了西方郊区化建设的理念、优缺点及对于我国当前乡村振兴战略背景下郊区建设的借鉴意义;指出应学习西方在郊区建设规划上对人文主义的重视,从文化认同、群体结构和综合服务等方面入手,避免出现西方正经历的“郊区功能从属城镇化”“功能单一同质化”等负面现象。我国的郊区建设应该放眼于乡村振兴的大背景下,切实认清农耕文化和宗亲制度逐渐衰落这一现实,以西方郊区化的发展理念和表现作为借鉴,探寻建设具有多样化,弱化阶层分化和具备自我独立性特征的乡村郊区社区;同时,以平等互助式理念推进郊区建设,强调多群体参与和以个人为基本单位的群体性建设,以及养老服务业为主的综合性生产生活体系。

从美国城市郊区化看中国城市郊区化

城市郊区化是城市发展的必经阶段。本文从美国城市郊区化的发展进程及存在的问题出发,结合已有的郊区化理论成果,分析了我国城市郊区化的发展过程、驱动机制和郊区化所产生的经济、社会、环境效益。

中国城市郊区化进程中的无序蔓延:表征、隐患及政府应对策略

中国城市郊区化进程中无序蔓延的表现特征主要有:加速度、低密度蔓延;拼贴式、破碎性蔓延;蛙跳式、跃迁性蔓延;非配套、非同步性蔓延;功利化、矛盾伴生性蔓延等。其带来的潜在隐患主要包括:对我国粮食安全、社会稳定、生态安全以及城市健康运行造成的隐患。应对中国城市郊区化进程中无序蔓延的政府策略主要有:政府角色的转变;政府引导方向的转变;政府规划编制的转型;政府推进城市拓展模式的转型;政府郊区建设、管理与保护的转变等。

Dynamics of Nitrogen Speciation in Horticultural Soils in Suburbs of Shanghai,China

Dissolved organic nitrogen （DON） represents a significant pool of soluble nitrogen （N） in soil ecosystems. Soil samples under three different horticultural management practices were collected from the Xiaxiyang Organic Vegetable and Fruit Farm, Shanghai, China, to investigate the dynamics of N speciation during 2 months of aerobic incubation, to compare the effects of different soils on the mineralization of ^14C-labeled amino acids and peptides, and to determine which of the pathways in the decomposition and subsequent ammonification and nitrification of organic N represented a significant blockage in soil N supply. The dynamics of N speciation was found to be significantly affected by mineralization and immobilization. DON, total free amino acids, and NH^＋-N were maintained at very low levels and did not accumulate, whereas NO3^--N gradually accumulated in these soils. The conversion of insoluble organic N to low-molecular-weight （LMW） DON represented a main constraint to N supply, while conversions of LMW DON to NH4^＋-N and NH4^＋-N to NO3^--N did not. Free amino acids and peptides were rapidly mineralized in the soils by the microbial community and consequently did not accumulate in soil. Turnover rates of the additional amino acids and peptides were soil-dependent and generally followed the order of organic soil 〉 transitional soil 〉 conventional soil. The turnover of high-molecular-weight DON was very slow and represented the major DON loss. Further studies are needed to investigate the pathways and bottlenecks of organic N degradation.

Comparison on Soil Carbon Stocks Between Urban and Suburban Topsoil in Beijing, China

The urban population and urbanized land in China have both increased markedly since the 1980 s. Urban and suburban developments have grown at unprecedented rates with unknown consequences for ecosystem functions. In particular, the effect of rapid urbanization on the storage of soil carbon has not been studied extensively. In this study, we compared the soil carbon stocks of different land use types in Beijing Municipality. We collected 490 top-soil samples(top 20 cm) from urban and suburban sites within the Sixth Ring Road of Beijing, which cover approximately 2400 km2, and the densities of soil organic carbon(SOC), soil inorganic carbon(SIC), and total carbon(TC) were analyzed to determine the spatial distribution of urban and suburban soil carbon characteristics across seven land use types. The results revealed significant differences in soil carbon densities among land use types. Additionally, urban soil had significantly higher SOC and SIC densities than suburban soil did, and suburban shelterbelts and productive plantations had lower SIC densities than the other land use types. The comparison of coefficients of variance(CVs) showed that carbon content of urban topsoil had a lower variability than that of suburban topsoil. Further findings revealed that soil carbon storage increased with built-up age. Urban soil built up for more than 20 years had higher densities of SOC, SIC and TC than both urban soil with less than 10 years and suburban soil. Correlation analyses indicated the existence of a significantly negative correlation between the SOC, SIC, and TC densities of urban soil and the distance to the urban core, and the distance variable alone explained 23.3% of the variation of SIC density and 13.8% of the variation of TC density. These results indicate that SOC and SIC accumulate in the urban topsoil under green space as a result of the conversion of agricultural land to urban land due to the urbanization in Beijing.

Chemical compositions and source apportionment of atmospheric PM_(10) in suburban area of Changsha, China

Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence （WD-XRF）. Source appointment was implemented by the principal component analysis/absolute principal component analysis （PCA/APCA） to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from （85.6±43.7） μg/m3 in July 2008 to （107.6±35.7） μg/m^3 in October 2008, the concentrations of the anthropogenic elements （P, S, C1, K, Mn, Ni, Cu, Zn, and Pb） are basically increased but concentrations of the natural elements （Na, Mg, Al, Si, Ca, Ti, and Fe） are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China： soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants.

Impacts of Suburbanization on Urban Eco-environment of Xi'an in China

Suburbanization in large cities is an important phenomenon in the process of urbanization development in China in recent decades,which plays a very important role in promoting city development,whereas some side effects on the eco-environment appeared at the same time.This paper,taking Xi'an City in China as a case study site,analyzed the features of population suburbanization and industry suburbanization and pointed out the impacts of suburbanization on urban eco-environment.Based on the research,suggestions of countermeasures for urban planning and municipal management of Xi'an City in protecting urban eco-environment and conserving natural ecology were put forward in the end.

Simulation Analysis on Spatial Pattern of Urban Population in Shenyang City,China in Late 20th Century

The spatial distribution of urban population can reflect significantly urban functions and development status. Shenyang, as a typical old industrial city in China, has experienced considerable changes in spatial distribution of population in the process of urban transformation, resulting in the change of urban spatial structure. Based on the sub-district data of Chinese national population censuses in 1982, 1990 and 2000, this study simulates the evolution pattern of spatial distribution of urban population in Shenyang City. Using statistical method and exploratory spatial data analysis (ESDA), we found that the population distribution, on the whole, has presented a balanced and decentralized trend since the 1980s, which characterizes with Chinese suburbanization. Furthermore, based on the investigation of the pattern of population distribution, it is concluded that the negative exponential model fitted the distribution best, and population concentration in the inner suburb kept increasing gradually, meanwhile, the spatial structure of population distribution has presented a polycentric feature since the 1980s. The parameters of the model show that population in the urban core concentrate significantly all the time. The increase of population in the inner suburb influences the population distribution pattern more and more importantly, but the concentration intensity of population cores in inner suburb is still low.

STUDY ON HIV/STDS KNOWLEDGE AND RISK BEHAVIORS RELATED FACTORS AMONG FEMALE SEX WORKERS IN SHANGHAI,CHINA

Objective To assess the HIV/STDs knowledge and risk behaviors related factors among female sex workers(FSWs)in Shanghai,China.Methods A cross-sectional study was conducted in 5 districts(including 3 suburbs and 2 urban districts).A total of 324 FSWs from 88 massage parlors and hair-beauty salons participated in the survey.An interviewer-administrated questionnaire was used to collect information.Results The average score of HIV/STDs knowledge was 15.2±3.9.Multivariate analyses indicated that limited education [odds ratio(OR):8.6,95% confidence interval(CI):2.9-25.6],coming from suburbs [odds ratio(OR):3.7,95% confidence interval(CI):2.0-6.8],monthly income less than 1500 RMB(220 US$)[odds ratio(OR):3.9,95% confidence interval(CI):1.9-8.1],without HIV/STDs-related education experience(OR:5.2,95% CI:2.8-9.5),and coming from provinces of low epidemic(OR:2.7,95% CI:1.1-6.6)were significant predictors of lower HIV/STDs knowledge.And 29.5% FSWs had sex without a condom when clients paid much more money,and 46.3% had the experience of condom broke or slipped during commercial sexual intercourse.Conclusion Health promotion should be conducted to enhance HIV/STDs knowledge and reduce risk behaviors among FSWs from suburbs with limited education in Shanghai especially.

Daytime HONO formation in the suburban area of the megacity Beijing, China

Nitrous acid （HONO）, as a primary precursor of OH radicals, has been considered one of the most important nitrogencontaining species in the atmosphere. Up to 30% of primary OH radical production is attributed to the photolysis of HONO. However, the major HONO formation mechanisms are still under discussion. During the Campaigns of Air Quality Research in Beijing and Surrounding Region （CAREBeijing2006） campaign, comprehensive measurements were carried out in the megacity Beijing, where the chemical budget of HONO was fully constrained. The average diurnal HONO concentration varied from 0.33 to 1.2 ppbv. The net OH production rate from HONO, Pon（HONO）net, was on average （from 05：00 to 19：00） 7.1 × 10^6 molecule/（cm^3 s）, 2.7 times higher than from 03 photolysis. This production rate demonstrates the important role of HONO in the atmospheric chemistry of megacity Beijing. An unknown HONO source （Punknown） with an average of 7.3 × 10^6 molecule/（cm^3 s） was derived from the budget analysis during daytime. Punknown provided four times more HONO than the reaction of NO with OH did. The diurnal variation of Punknown showed an apparent photo-enhanced feature with a maximum around 12：00, which was consistent with previous studies at forest and rural sites. Laboratory studies proposed new mechanisms to recruit NO2 and J（NO2） in order to explain a photo-enhancement of of Puknown. In this study, these mechanisms were validated against the observation-constraint Punknown. The reaction of exited NO2 accounted for only 6% of Puknown, and Punk poorly correlated with [NO2] （R = 0.26） and J（NO2）[NO2] （R = 0.35）. These results challenged the role of NO2 as a major precursor of the missing HONO source.