Beijing-Tianjin Region Research Articles

Evaluation, Driving Mechanism and Spatial Correlation Analysis of Atmospheric Environmental Efficiency in the “2+26” Cities Based on the Nonradial MEA Model

The “2+26” cities are 26 cities in Beijing, Tianjin and the surrounding cities, constituting a region characterized by economic prosperity and diverse industries but plagued by severe atmospheric pollution. As a focal area for atmospheric pollution control, a scientific assessment of atmospheric environmental efficiency in the “2+26” cities that measures the degree of coordination between the economy and air pollution is very important for winning the battle of blue sky defense. Based on this, this study comprehensively used the nonradial multi-directional efficiency analysis (MEA) model, Global Reference Malmquist Model and spatial correlation analysis to evaluate the atmospheric environmental efficiency, calculate the driving factors and explore the spatiotemporal distribution characteristics of the “2+26” cities from 2009 to 2018. The research findings indicate the following: (1) Atmospheric environmental efficiency showed a trend of first decreasing and then increasing, with a significant improvement potential of 26.7% in the future. (2) There was a significant discrepancy between the best- and worst-performing cities, with the best being 0.910 and the worst being 0.573, demonstrating imbalanced development between cities. The relatively low-efficiency cities were mainly located in Hebei, Shanxi and Henan provinces. (3) A value of technological efficiency change (EC) less than 1 was the main restrictive factor for improving atmospheric environmental efficiency, whereas a value of technological change (TC) greater than 1 enhanced it. (4) The atmospheric environmental efficiency presented a distinct spatial distribution pattern of high–high and low–low aggregation, forming high-value areas centered in the Beijing–Tianjin region and along the Zibo–Zhengzhou line. The western and central regions were relatively low, whereas the northern and eastern regions were relatively high, with significant regional differences in spatial distribution. The conclusions from this article’s empirical analysis can help concerned developing countries determine key factors to improve their atmospheric environmental efficiency and then formulate policies for sustainable economic and environmental development.

The spatiotemporal evolution of rural landscape patterns in Chinese metropolises under rapid urbanization.

Understanding the evolution of rural landscapes in metropolises during rapid urbanization is crucial for formulating policies to protect the rural ecological environment. In this study, remote sensing and geographical information system data, as well as applied landscape index analysis, are used to examine the spatiotemporal evolution of rural landscape patterns in the Beijing-Tianjin region of China, which has experienced rapid urbanization. The relationships between land use/land cover changes and changes in rural landscape patterns are explored. The results revealed significant spatial differences in the rural landscapes in the Beijing-Tianjin region; farmland and forestland were the main types of landscapes, creating a "mountain-field-sea" natural landscape pattern. The conversion of rural landscapes in the Beijing-Tianjin region involved mainly the conversion of farmland to urban areas, with few exchanges between other landscape types. The urban areas in the Beijing-Tianjin region increased by 3% per decade; farmland decreased at the same rate. Additionally, the rural landscape patterns in the Beijing-Tianjin region were dominated by fragmentation, dispersion, and heterogeneity and moved from complex to regular. Water bodies displayed the most fragmented natural landscape; their number of patches increased by 36%, though their network characteristics were maintained. Forestland was the most concentrated natural landscape. In this study, theoretical support and a scientific reference for the optimization of rural landscape patterns and the improvement in rural living environments in rapidly urbanizing areas are provided.

Research on the Current Situation and Protection Measures of the Water Environment of Tianjin Qilihai Wetland

The Qilihai Wetland located in Tianjin is one of the important wetlands in northern China and an important transfer station for migratory birds. Its water environment quality is crucial for improving the regional ecosystem function, and is therefore known as the “green lung of the Beijing-Tianjin region”. This paper conducted on-site monitoring and a comprehensive evaluation of the current situation of the Qilihai environment during the dry season and the rainy season. Based on this, countermeasures and suggestions for water environment protection were proposed from the aspects of optimizing water sources, reducing interference, and strengthening governance.

Evaluation of the operation status of the residential land market in Beijing-Tianjin-Hebei region of China and its spatiotemporal pattern characteristics.

Exploring the operation status and patterns of urban land markets is an important theoretical and practical topic for promoting coordinated socio-economic development. In this study, the operation status of the residential land market in the Beijing-Tianjin-Hebei region and the characteristics of its pattern were analyzed using the composite index method and the 3σ rule of the normal distribution and taking the 174 counties in Beijing, Tianjin, and Hebei, China, as the research objects. The results show that ① Beijing, Tianjin, Langfang, Zhangjiakou, and Baoding residential land market state composite indexes are all in the middle to upper levels in the Beijing-Tianjin-Hebei city cluster, while Qinhuangdao, Handan, and Chengde residential land market state composite indexes are generally low. The harmony between the residential land price and national economy, the market supply and demand balance, and the structural balance may become the main factors affecting the healthy development of the residential land market in Beijing and Tianjin. ② The proportion of counties with "healthy" residential land market in all dimensions and overall market status reached over 64%, and the residential land market in the Beijing-Tianjin-Hebei region is running well. The rapid increase in residential land prices from 2016 to 2020 was an important driver of the increased heat in the residential land market across the region. ③ The residential land market in the counties around Beijing and Tianjin is significantly hotter than in other regions, and there is an obvious polarization effect in the operation state of the residential land market in the Beijing-Tianjin region. The residential land market is generally cold in the counties in the southern and northeastern parts of the region and other peripheral areas, and there is a risk of marginalization in the development of the residential land market in the counties in the peripheral areas. ④ Both the hot and cold residential land market states exhibit spatial clustering characteristics. Most of the clusters are not consistent with the municipal administrative boundaries, and the states of the residential land market in neighboring counties are very similar.

Green finance network evolution and prediction: fresh evidence from China

Green finance has become an important reform force to promote the sustainable development of China's economy. Therefore, it has a great significance for in-depth analysis of the advantages and disadvantages of regional green finance development, to further promote it by clarifying and predicting the regional differences and dynamic evolution trends. Based on this, this paper will select the relevant index from 2001 to 2020 to construct China Green Finance Core Network (CGFCN) in different years by using Space-L method at the first, then analyze its network characteristics and spatial evolution pattern in depth, and finally predict the future development trend of CGFCN by link prediction. The research results show that: firstly, the evolution of CGFCN is mainly divided into three stages: rapid development, stable development and optimal development, and the closeness of CGFCN is constantly improving. Besides, two strong relationship networks are gradually forming, that is Beijing-Tianjin region and the Yangtze River Detla region. Secondly, with the development of green finance, the community division has changed. It is mainly divided into four communities, named the Beijing-Tianjin-Hebei leading community, the eastern provincial community, the Yangtze River Delta community and the central and southern joint community. Different communities will have different integration in different periods. Thirdly, the future development direction of green finance network is mainly Beijing-Tianjin-Hebei region and Yangtze River Delta regions, and their outward radiation are mainly shown in the eastern coastal and central regions, which also have strong development potential. In this regard, it is proposed to coordinate development across provinces to speed up the "urban integration" of green finance services; Establish an efficient community development mechanism and promote the interconnection of green finance markets and infrastructure between different regions; Strengthen the resource flow among regions and coordinate the resource competition of green finance.

Embodied carbon transfers and employment-economic spillover effects in China’s inter-provincial trade

Understanding the embodied carbon transfer in inter-provincial trade and its employment-economic spillover effects is of crucial value in achieving carbon equity management. Surprisingly, few studies have focused on the intrinsic relationship between embodied carbon, embodied GDP, and embodied employment in iinter-provincial trade and its equity implications. Based on the 2012 and 2017 multi-regional input-output tables, our study of inter-provincial trade in 30 Chinese provinces shows that: 1) net outflows of embodied carbon were concentrated in the Beijing-Tianjin region and the eastern and southern coastal regions, while net inflows were in the central and northwestern regions; 2) embodied carbon, GDP, and employment were characterized by nearby transfer, complementary energy economy, and asymmetric transfers in and out; and 3) western provinces, which relied heavily on traditional energy and heavy chemical industries, gained a competitive disadvantage implying by the internal relationship between net transfers of embodied carbon, GDP, and employment. To mitigate the inequity of inter-provincial carbon trade, top-down climate goals must be aligned with bottom-up socio-economic incentives to achieve balanced regional development and improved public welfare.

Human exposure to phthalate esters in soils embodied in interregional food trade in China

The ubiquitous occurrence of phthalate esters (PAEs) in agricultural soil results in their inevitable accumulation in crops, potentially increasing the risk of human exposure to PAEs via daily food intake. Dietary health risk of PAEs not only depends on locally produced food but also the imported food from other regions. However, the impact of interregional food trade on human dietary exposure to PAEs has been seldom assessed. Herein, we investigated the impact of interregional food trade on the dietary exposure to PAEs that contributed from soil contamination in China. The average daily dietary intake of PAEs for the Chinese general population was 24.3 μg/kg/day when assuming the total consumption of crops from local market only, while the average daily dietary intake of PAEs for the Chinese general population was decreased by 2.9% when the effects of interregional food trade were involved into the calculation. Additionally, the interregional food trade remarkably increased the daily dietary intake of PAEs in the regions of Beijing-Tianjin region (47.8%), North (21.4%) and Central (4.26%). As a result, the hazard quotient value of PAEs in the regions of Beijing-Tianjin region, North and Central increased by 29.4%, 11.0% and 5.0%, respectively, owing to the consumption of imported crops from the highly PAEs contaminated regions. In contrast, the daily intake and hazard quotient value of PAEs in the regions of Central Coast, Northwest, Northeast and South Coast decreased due to the interregional trade. These results indicated that the interregional food trade promoted the transfer of PAEs between regions and thus altered the potential risk to the local population. Overall, this study highlights the importance of taking the interregional food trade into account to provide a more accurate risk assessment of dietary exposure to pollutants.

Analysis of China's regional differences in water consumption based on spatial structural decomposition analysis model

Analyzing the factors that affect the spatial differences in production water consumption in China is necessary to implement its most stringent water resource management system effectively. Based on the input-output tables of 31 provinces and the water-consumption data of provinces by sectors in 2017, the water consumption-economy input-output tables of 31 provinces are constructed. The spatial structural decomposition analysis method is used to analyze the impact of technology level, economic scale, and regional characteristics on spatial differences in production water consumption. The final demand effect is then decomposed into final demand sectoral structural effect, final demand distribution structure effect, population-scale effect, and consumption-level effect. The results show that production water consumption depends on the economic scale and regional characteristics. Xinjiang, Jiangsu, Guangdong, Heilongjiang, and most provinces in the central region use more production water than the average level, while those in the Beijing-Tianjin region and most in the North-west region use less than average. The decomposition results show that the technical and the final demand effects are the main factors for the spatial differences. The impact of population-scale and consumption-level contribute the most to the final demand effect.

Creating Engines of Prosperity: Spatiotemporal Patterns and Factors Driving Urban Vitality in 36 Key Chinese Cities.

Under the requirements of new urbanization in China, the improvement of urban spatial vitality has become a key aspect of the territory development plan. Based on the theory of urban vitality by Jacobs, this study analyzed the spatiotemporal characteristics of mobility, diversity, and regularity from urban vitality in 36 key Chinese cities from 1990 to 2015; the urban vitality was evaluated by considering the society, economy, environment, culture, and cyberspace and by exploring its driving factors. The results suggest that vitality was higher in the southern/eastern coastal cities than in the northern/western inland ones. Cities with the highest vitality levels (top 10) were mostly located in the Pearl and Yangtze River deltas, the Beijing-Tianjin region, and the middle reaches of the Yangtze River. Shenzhen demonstrated the highest vitality in the stage of extremely high coordination. Most of the cities with a middle level of vitality were located in northern China, while cities with poor vitality were small-scale cities with underdeveloped economies in the west and provincial capitals in northeastern China with a shrinking population. Areas with high-density facilities, high-accessibility transportation, multiple functional land use, and a high standard of living always have high vitality. The point of interest density had a significant positive effect on daytime vitality in regions with moderate and high vitality, but varying effects on nighttime vitality; it had a higher influence on nighttime vitality than on daytime vitality in areas of extremely high vitality. The study also provides corresponding measures for infrastructure, which could be invested in and constructed at different urban development stages to promote vitality. This could provide guidance for creating a booming space and revitalize and increase urban vitality, and could help reasonably regulate and control urban population and land use.

Design of Air Passenger Travel Choice Intention Prediction System Based on Deep Learning

Under the Beijing-Tianjin regional comprehensive transportation system, the flow of air passengers between multiple airports in the region is more frequent. The fundamental reason for the flow of air passengers is that there are differences in the level of service quality provided by airports and airlines in the region. Passengers’ choice intention is the consumption and purchase decision of passengers on aviation services. By constructing a Logit model, this paper analyzes the degree of influence on the travel choice intention of air passengers in the Beijing-Tianjin region from five aspects: individual passenger demographic characteristics, travel purpose, ground transportation characteristics, airport operation capacity, and airport soft power. Passengers can effectively predict the choice of air travel mode in the Beijing-Tianjin region. The results show that Beijing Capital Airport is favored by business travelers; Beijing Daxing International Airport is favored by travelers because of its fast security check-through speed; for Tianjin Binhai International Airport, the convenience of getting in and out of the airport by car and the speed of airport security check-through are two significant factors. Indicators do not affect the selection of airports; reasonable follow-up arrangements when airport flights are delayed are the only significant but negatively correlated factor; the research design results provide new ideas for the analysis of passenger travel mode selection behavior in multiple airport areas, enriching the data-driven research on transportation choices.

Analysis of Labor Embodied in China’s Inter-regional Trade in Value-Added: Re-Examination of Leontief’s Paradox from the Perspective of Energy Use

Based on the multi-regional input-output framework, this paper analyzed the labor and energy transfer embodied in interregional trade in China. Meanwhile, through estimating the energy intensity per unit of labor embodied in final products in each region, this study examines whether the empirical results are consistent with the theoretical hypothesis and provides relevant explanations and industrial development suggestions. Results show that east coastal region and central region are the two main participants in interregional trade. As for the labor embodied in trade, east coastal region is the largest exporter of embodied labor, though it has the highest wage among eight regions; in contrast, north coastal and southwestern region, with relatively low wage, are the two largest importer of embodied labor. As for the energy embodied in trade, northwestern region is the largest exporter of embodied energy. Further analysis indicates that the energy intensity per unit of labor in region with relatively low GRP (such as northwestern region) is the highest, whereas those in Beijing-Tianjin Region and south coastal region (with relatively high GRP) are the lowest. By analyzing the Revealed Comparative Advantage in each region, the paper finds that the main reason for this inconsistency lies in the industrial structure in northwestern and north coastal region, which are highly dependent in primary industries. Improving the infrastructure and upgrading industrial structure are important steps for these regions to transform the extensive growth mode.

Environmental Regulation, Government Subsidies, and Green Technology Innovation-A Provincial Panel Data Analysis from China.

Economic development in the “new era” will require green innovation. To encourage the growth of green technology innovation, it has become fashionable to strengthen environmental regulation. However, the impact of environmental regulation on green technology innovation, as well as the role of government subsidies, needs to be examined. Utilizing fixed-effect models and 2SLS models to explore the impact of environmental regulation on green technology innovation in China from 2003 to 2017, this research sought to examine whether environmental regulations impact green technology innovation, as well as the role of government subsidies in the above-mentioned influence path. The findings support the Porter Hypothesis by demonstrating an inverted “U” relationship between environmental regulation and green technology innovation. The impact of environmental regulation on green technology innovation varies by region. To be specific, there is an inverted “U” relationship between environmental regulation and green technology innovation in China’s central and central coast regions. In comparison, the north area, southern coast, and southwest region exhibit a “U” relationship between the two. The relationship is not significant in the Beijing-Tianjin region. Additionally, government subsidies act as an intermediate in this process, positively influencing firms to pursue green technology innovation during the earliest stages of environmental regulation strengthening. However, government subsidies above a certain level are unproductive and should be used appropriately and phased off in due course.

How to reconcile land use conflicts in mega urban agglomeration? A scenario-based study in the Beijing-Tianjin-Hebei region, China

With the development of global urbanization, land use conflicts have become one of the major issues hindering sustainable land use and human-environment coordination in urbanized areas. In this context, reconciliation of land use conflicts requires urgent attention. By taking the Beijing-Tianjin-Hebei (BTH) urban agglomeration as a case study area, the spatial comprehensive conflict index (SCCI) was constructed to identify and evaluate land use conflicts. Besides, the impacts of rapid urbanization and terrain restriction on land use conflicts were also explored using the coupling coordination degree (CCD) model and terrain index, respectively. Then, the Dyna-CLUE model was adopted to simulate land use conflicts under three adaptive scenarios in 2030. Results show that: (1) During 2000–2015, land use conflicts in the BTH region demonstrated an overall mitigating trend, and their spatial patterns remained relatively stable, characterized by significant cluster and belt agglomeration. (2) Land use conflicts were significantly intensified in areas experiencing rapid urban-rural transformation and terrain transition, and two typical conflict zones were identified, i.e. the urban-rural interface of the Beijing-Tianjin region and the terrain transition area located in the Taihang Mountains, Yan Mountains and Bashang Plateau. (3) In 2030, land use conflicts in the BTH region manifest overall mitigation under the ecological security (ES) scenario, while demonstrating an intensifying trend under the business as usual (BAU) scenario and cropland protection (CP) scenario. Based on simulation results, land use spatial optimization modes at county level for the BTH region were formulated. In face of increasingly prominent land use conflicts globally, this study will provide a scientific reference for policymaking in pursuit of sustainable land use management for the BTH region and urban agglomerations in other parts of the world.

Spatiotemporal changes in terrestrial water storage in the Beijing-Tianjin Sandstorm Source Region from GRACE satellites

The Sandstorm Source Control Project in and around the Beijing-Tianjin region was one of the most important ecological projects in China. Terrestrial water storage (TWS) has important impacts on the ecological construction, agriculture, industry, and resident’s lives. Based on the Gravity Recovery and Climate Experiment (GRACE) data, meteorological and Moderate Resolution Imaging Spectroradiometer (MODIS) data, etc., this paper analyzed spatiotemporal characteristics of TWS, groundwater storage, and precipitation, and explored the influencing factors of regional TWS combined with land use and land cover (LULC), social and economic data. The most important results were as follows: (1) From 2003 to 2016, TWS in the Beijing-Tianjin Sandstorm Source Region showed a decreasing trend with a rate of 3.14 mm yr−1. (2) The TWS decline was caused mainly by groundwater overexploitation, but not precipitation variation. (3) Spatiotemporal variations of TWS were related to LULC. The area with the most serious decrease of TWS was mainly located in the southwestern part of the region, where farmland percentage and population density were greater. (4) Reducing the percent of farmland and tree planting, and adding the shrub and grass planting, could be a viable choice for the Beijing-Tianjin Sandstorm Source Control Project. These results provide a scientific basis for regional water resource and ecological management.

Urban heat island circulations over the Beijing-Tianjin region under calm and fair conditions

The Beijing-Tianjin-Hebei region has experienced severe urban heat island (UHI) effects in recent decades. Using the Weather Research and Forecasting (WRF) model and the new World Urban Database and Access Portal Tools (WUDAPT) land-use dataset, the urban heat island circulations (UHICs) and other local atmospheric circulations over Beijing and Tianjin were studied during a severe UHI event in 2012. It was shown that in the daytime, various UHICs over Beijing and Tianjin developed separately under a southerly background wind. Two of these UHICs formed over Beijing due to multiple hot regions, involving a chain flow mechanism in which the outflows from one UHIC over nearby mountains were connected to the inflows to the other UHICs in a west-to-east direction. At night, more robust UHICs occurred and a chain flow mechanism again formed over the Beijing-Tianjin region, as the upper-level outflows from the UHIC over Tianjin were connected to the inflows of the UHIC over Beijing. Moreover, the rotary air movements formed by the flows over the mountain and the down-slope winds formed a convergent region in the northwest of Beijing. In particular, sensitivity experiments replacing either Beijing or Tianjin with cropland grids revealed that the presence of either of those urban areas modified the penetration of the sea-breeze circulation. The city shape was found to affect the UHIC over Beijing at night, as the convergent zones were distributed diagonally and the wind speeds were higher in the diagonal direction.

Rural Residential Land Transition in the Beijing-Tianjin-Hebei Region: Spatial-Temporal Patterns and Policy Implications

Rural residential land transition (RRLT) dominates rural land use transition. Therefore, analysing the laws of transition and differentiation of land use is not only the basis for the differential management of rural residential areas but key to the sustainable use of rural land. This study constructs a conceptual model of RRLT using multi-period remote sensing monitoring data based on a comprehensive index method, ArcGIS, and FRAGSTATS landscape pattern analysis, among others. It also analyses the characteristics of the transition extent, transition trend, transition morphology, and transition intensity of rural residential land in the Beijing-Tianjin-Hebei (BTH) region from 1980 to 2018. The results show that, from a vertical comparison of long time series, the transition extent is characterised by a process of ‘slow growth—expanding start—fast expansion—slowing down’; the transition trend is characterised by an increase in the amount of cultivated land occupied by rural residential land, followed by a large number of rural residential land is reclaimed as cultivated land; the transition morphology is characterised by an increase in mean patch size and degree of irregularity, as well as aggregation; and the transition intensity is characterised by fluctuations in the process of ‘small-scale reduction—small-scale growth—substantial growth—small-scale growth and reduction’. A horizontal comparison of counties in the BTH region reveals a long-lasting and active growth trend in transition extent and transition intensity in the Beijing-Tianjin region, and a gradually slowing trend in the areas around the region. The transition morphology features of the northwest Hebei region are more prominent, and show that the scale of rural settlements is small, the plaques fragmented and irregular, and the layout more scattered. The BTH region should formulate a differentiated transition direction for rural residential areas based on the different functional areas, and play into the agglomeration, scale, and synergy effects of urban agglomerations. It should also coordinate and improve the human–land relationship in rural areas, and construct an orderly and densely distributed pattern of urban and rural spatial development with a reasonable layout and complementary functions.

Structural heterogeneity and proximity mechanism of China’s inter-regional innovation cooperation network

ABSTRACT Based on the cooperation patent data between 31 provinces in China from 1985 to 2017, this paper portrays the topological structure, spatial pattern and proximity mechanism of China’s inter-regional innovation cooperation network by the graph theory, spatial statistical methods and the quadratic assignment procedure model. The conclusions are as follows: (1) the topological structure of China’s inter-regional innovation cooperation forms a hierarchical network with Beijing as the core and it exhibits a typical small-world property and ‘core–periphery’ structure. (2) In terms of spatial distribution characteristics, the ‘quadruple’ with the Beijing–Tianjin region, Yangtze River Delta, Pearl River Delta and Sichuan as the peaks has become the backbone of the inter-regional innovation cooperation network in China. At the same time, the spatial differentiation of the three indicators of degree centrality, median centrality and intensity centrality is obvious. (3) In terms of proximity mechanism, geographical, institutional and cognitive proximity exert a significant effect on China’s inter-regional innovation cooperation network linkage. However, there are significant differences in the effects of various proximity elements on China’s regional innovation network.

An empirical study of transboundary air pollution of the Beijing-Tianjin region

In this paper, we present a stochastic differential game to model the transboundary air pollution problems of the Beijing-Tianjin region with emission permits trading. By using stochastic optimal control theory, we obtain the Hamilton-Jacobi-Bellman equation satisfied by the value function for the cooperative games. Next, we solve the Hamilton-Jacobi-Bellman equation by using a fitted finite volume method. Finally, the efficiency and the usefulness of the fitted finite volume method are illustrated by an empirical study.

Development history and accessibility evolution of land transportation network in Beijing-Tianjin-Hebei region over the past century

From the development of modern transportation to the current era of high-speed transportation networks, the Beijing-Tianjin-Hebei (BTH) region has always played a national leading role in land transportation development of China. In order to explore the long-term evolutionary characteristics of land transportation in the BTH region, this paper utilized a temporal scale of 100 years to systematically interpret the development process of the land transportation network. Taking 13 cities within the BTH region as research anchor cities, we took into account “leaping” mode of transportation in order to investigate the evolution of accessibility. Our research shows the following results: (1) The land transportation network in the BTH region has undergone five stages of development: the initial period of modernization (1881–1937); the period of stagnation of transportation development (1937–1949); the network expansion period (1949–1980); the period of trunk construction (1980–1995), and the period of high-speed transportation network development (1995–present). The network structure centered around Beijing has existed from the outset of modern transportation development. (2) The accessibility spatial pattern of land transportation in BTH region has evolved from expansion along traffic corridors to the formation of concentric circles. The stratified circular structure of transportation in anchor cities has gradually developed into a contiguous development pattern. (3) There are clear hierarchical differences in the transportation structures of anchor cities. Beijing has always been at the top of this hierarchy, while the hierarchical position of Zhangjiakou has fallen noticeably since 1949. The Beijing-Tianjin region was the first region to form a short-duration transportation circle structure, while the transportation advantages of the central part of Hebei Province, which is located in the center of the BTH transportation region, have yet to be realized.

Contamination and ecological risks of toxic metals in the Hai River, China

Contamination of trace metals in urban rivers is a global problem. The objective of this study was to investigate the contamination and ecological risks of trace metals in the Hai River, which receives substantial effluents from the Beijing-Tianjin region. A total of 43 surface water and sediment samples were collected and analyzed for physiochemical properties and toxic elements. The concentrations of Cd, Cr, Ni, Pb, Cu and Zn in the river water met the Chinese environmental quality grade I standards for surface water. The average total concentrations of Zn, Cr, V, Cu, Pb, Ni, Co, Sc and Cd in the sediments were 144.2, 77.5, 70.1, 46.1, 40.1, 29.6, 12.4, 9.9 and 0.26 mg/kg, respectively. The enrichment of Cd, Cr, Cu, Pb and Zn in the sediments was influenced by anthropogenic activity, as indicated by the enrichment factor (EF) and multivariate analysis. The concentrations of Co and Cr in the sediments were predominantly in residual fractions, while relatively higher amounts of Cd, Pb, Zn and Cu were in non-residual fractions. There was a significant correlation between concentrations of Cd, Co, Cr, Cu, Pb and Zn in non-residual fractions and their corresponding EF values (P < 0.01). This result further demonstrated that anthropogenic inputs were an important contributor to metal enrichment. The high bioavailability of Cd and poor bioavailability of Co and Cr in the sediments were demonstrated by the single extraction procedure. The significant correlation between concentrations of Cd, Cu, Pb and Zn in non-residual fractions and their concentrations in EDTA-extractable fractions was established (P < 0.01). This result indicates that single-step EDTA extraction may represent a useful procedure for assessing the bioavailability of Cd, Cu, Pb and Zn in riverine sediments. The ecological risks of the metals studied in the Hai River sediments were at a low level, dominated by the risks imposed by Cd.