Xianjin Huang

Soil Pollution: Urban Brownfields

Chinas plans to tackle farmland pollution and improve food safety are to be welcomed (“China gets serious about its pollutant-laden soil,” C. Larson, News & Analysis, 28 March, p. [1415][1]). However, the country faces equally serious urban soil and water pollution. As a result of unparalleled

Spatial Variability of Soil Organic Carbon and Related Factors in Jiangsu Province, China

Abstract Soil organic carbon (SOC) plays a key role in the global carbon cycle. In this study, we used statistical and geostatistical methods to characterize and compare the spatial heterogeneity of SOC in soils of Jiangsu Province, China, and investigate the factors that influence it, such as topography, soil type, and land use. Our study was based on 24 186 soil samples obtained from the surface soil layer (0–0.2 m) and covering the entire area of the province. Interpolated values of SOC density in the surface layer, obtained by kriging based on a spherical model, rang ed between 3.25 and 32.43 kg m−3. The highest SOC densities tended to occur in the Taihu Plain, Lixia River Plain, along the Yangtze River, and in high-elevation hilly areas such as those in northern and southwest Jiangsu, while the lowest values were found in the coastal plain. Elevation, slope, soil type, and land use type significantly affected SOC densities. Steeper slope tended to result in SOC decline. Correlation between elevation and SOC densities was positive in the hill areas but negative in the low plain areas, probably due to the effect of different land cover types, temperature, and soil fertility. High SOC densities were usually found in limestone and paddy soils and low densities in coastal saline soils and alluvial soils, indicating that high clay and silt contents in the soils could lead to an increase, and high sand content to a decrease in the accumulation of SOC. SOC densities were sensitive to land use and usually increased in towns, woodland, paddy land, and shallow water areas, which were strongly affected by industrial and human activities, covered with highly productive vegetation, or subject to long-term use of organic fertilizers or flooding conditions.

Improving air pollution control policy in China—A perspective based on cost–benefit analysis

To mitigate serious air pollution, the State Council of China promulgated the Air Pollution Prevention and Control Action Plan in 2013. To verify the feasibility and validity of industrial energy-saving and emission-reduction policies in the action plan, we conducted a cost-benefit analysis of implementing these policies in 31 provinces for the period of 2013 to 2017. We also completed a scenario analysis in this study to assess the cost-effectiveness of different measures within the energy-saving and the emission-reduction policies individually. The data were derived from field surveys, statistical yearbooks, government documents, and published literatures. The results show that total cost and total benefit are 118.39 and 748.15 billion Yuan, respectively, and the estimated benefit-cost ratio is 6.32 in the S3 scenario. For all the scenarios, these policies are cost-effective and the eastern region has higher satisfactory values. Furthermore, the end-of-pipe scenario has greater emission reduction potential than energy-saving scenario. We also found that gross domestic product and population are significantly correlated with the benefit-cost ratio value through the regression analysis of selected possible influencing factors. The sensitivity analysis demonstrates that benefit-cost ratio value is more sensitive to unit emission-reduction cost, unit subsidy, growth rate of gross domestic product, and discount rate among all the parameters. Compared with other provinces, the benefit-cost ratios of Beijing and Tianjin are more sensitive to changes of unit subsidy than unit emission-reduction cost. These findings may have significant implications for improving Chinas air pollution prevention policy.

Enforcement key to China's environment

On 1 January 2015, China formally began implementing its revised Environmental Protection Law (EPL). The new EPL offers some hope for sustainable development in China, but its potential may be limited if local governments continue to focus on the economy. Since the first EPL in 1989, China has

Impact of land use type conversion on carbon storage in terrestrial ecosystems of China: A spatial-temporal perspective.

Our work is the first study to explore the national and provincial composite carbon storage variations in terrestrial ecosystems of China caused by the entire flows of land use type conversion (LUTC). Only water body was excluded. The results indicated that terrestrial ecosystems of China lost 219 Tg-C due to LUTC from 1980 to 1995, and the amount was 60 Tg-C during the period 1995-2010. Despite the decrease in the total amount, carbon losses from LUTC intensified, but most of the losses were balanced by the opposite conversions. Our analyses also revealed that LUTCs in China were becoming detrimental to carbon reduction, mainly due to the insufficient increase of forest land to meet the growing demand for carbon absorption, the accelerating disappearance of grassland and the rapid expansion of settlements. More than 50% of the carbon storage variations for a single LUTC flow concentrated in several provinces. To improve China’s LUTC status from the aspect of low-carbon, Heilongjiang, Sichuan, Inner Mongolia, Tibet, Qinghai, Xinjiang and coastal regions, such as Shandong, Jiangsu and Liaoning, should be dealt with first according to their conditions. This study can be helpful to planners, policy makers and scholars concerned about carbon reduction in China.

Carbon emissions from land-use change and management in China between 1990 and 2010

Overall land-use change and management have contributed about 1.45 Pg of carbon to the total carbon released in China from 1990 to 2010. China has experienced enormous changes in land use in recent decades, which are largely driven by its unparalleled economic development. We analyze changes in vegetation and soil carbon storage between 1990 and 2010 resulting from combinations of land-use category conversion and management. Results demonstrate a major decline in grasslands (−6.85%; 20.83 × 106 ha) and large increases in urban areas (+43.73%; 6.87 × 106 ha), farmlands (+0.84%; 1.48 × 106 ha), and forests (+0.67%; 1.52 × 106 ha). The total soil organic carbon pool has been reduced by approximately 11.5 Tg of carbon (TgC) year−1, whereas 13.2 TgC year−1 has accumulated in the biomass carbon pool because of land-use category change. Large carbon losses (approximately 101.8 TgC year−1) have resulted from land management failures, including forest fires and insect pests. Overall land-use change and land management have contributed about 1.45 Pg of carbon to the total carbon released from 1990 to 2010. Our results highlight the importance of improving land-use management, especially in view of the recently proposed expansion of urban areas in China.

Spatial econometric analysis of carbon emissions from energy consumption in China

Based on energy consumption data of each region in China from 1997 to 2009 and using ArcGIS9.3 and GeoDA9.5 as technical support, this paper made a preliminary study on the changing trend of spatial pattern at regional level of carbon emissions from energy consumption, spatial autocorrelation analysis of carbon emissions, spatial regression analysis between carbon emissions and their influencing factors. The analyzed results are shown as follows. (1) Carbon emissions from energy consumption increased more than 148% from 1997 to 2009 but the spatial pattern of high and low emission regions did not change greatly. (2) The global spatial autocorrelation of carbon emissions from energy consumption increased from 1997 to 2009, the spatial autocorrelation analysis showed that there exists a “polarization” phenomenon, the centre of “High-High” agglomeration did not change greatly but expanded currently, the centre of “Low-Low” agglomeration also did not change greatly but narrowed currently. (3) The spatial regression analysis showed that carbon emissions from energy consumption has a close relationship with GDP and population, R-squared rate of the spatial regression between carbon emissions and GDP is higher than that between carbon emissions and population. The contribution of population to carbon emissions increased but the contribution of GDP decreased from 1997 to 2009. The carbon emissions spillover effect was aggravated from 1997 to 2009 due to both the increase of GDP and population, so GDP and population were the two main factors which had strengthened the spatial autocorrelation of carbon emissions.

Temporospatial changes of carbon footprint based on energy consumption in China

Study on regional carbon emission is one of the hot topics under the background of global climate change and low-carbon economic development, and also help to establish different low-carbon strategies for different regions. On the basis of energy consumption and land use data of different regions in China from 1999 to 2008, this paper established carbon emission and carbon footprint models based on total energy consumption, and calculated the amount of carbon emissions and carbon footprint in different regions of China from 1999 to 2008. The author also analyzed carbon emission density and per unit area carbon footprint for each region. Finally, advices for decreasing carbon footprint were put forward. The main conclusions are as follows: (1) Carbon emissions from total energy consumption increased 129% from 1999 to 2008 in China, but its spatial distribution pattern among different regions just slightly changed, the sorting of carbon emission amount was: Eastern China > Northern China > Central and Southern China > Southwest China > Northwest China. (2) The sorting of carbon emission density was: Eastern China > Northeast China > Central and Southern China > Northern China > Southwest China > Northwest China from 1999 to 2003, but from 2004 Central and Southern China began to have higher carbon emission density than Northeast China, the order of other regions did not change. (3) Carbon footprint increased significantly since the rapid increasing of carbon emissions and less increasing area of productive land in different regions of China from 1999 to 2008. Northern China had the largest carbon footprint, and Northwest China, Eastern China, Northern China, Central and Southern China followed in turn, while Southwest China presented the lowest area of carbon footprint and the highest percentage of carbon absorption. (4) Mainly influenced by regional land area, Northern China presented the highest per unit area carbon footprint and followed by Eastern China, and Northeast China; Central and Southern China, and Northwest China had a similar medium per unit area carbon footprint; Southwest China always had the lowest per unit area carbon footprint. (5) China faced great ecological pressure brought by carbon emission. Some measures should be taken both from reducing carbon emission and increasing carbon absorption.

Spatial Simulation of Land Use based on Terrestrial Ecosystem Carbon Storage in Coastal Jiangsu, China

This paper optimises projected land-use structure in 2020 with the goal of increasing terrestrial ecosystem carbon storage and simulates its spatial distribution using the CLUE-S model. We found the following: The total carbon densities of different land use types were woodland > water area > cultivated land > built-up land > grassland > shallows. Under the optimised land-use structure projected for 2020, coastal Jiangsu showed the potential to increase carbon storage, and our method was effective even when only considering vegetation carbon storage. The total area will increase by reclamation and the original shallows will be exploited, which will greatly increase carbon storage. For built-up land, rural land consolidation caused the second-largest carbon storage increase, which might contribute the most as the rural population will continue to decrease in the future, while the decrease of cultivated land will contribute the most to carbon loss. The area near the coastline has the greatest possibility for land-use change and is where land management should be especially strengthened.

Spatiotemporal Changes of Built-Up Land Expansion and Carbon Emissions Caused by the Chinese Construction Industry

China is undergoing rapid urbanization, enlarging the construction industry, greatly expanding built-up land, and generating substantial carbon emissions. We calculated both the direct and indirect carbon emissions from energy consumption (anthropogenic emissions) in the construction sector and analyzed built-up land expansion and carbon storage losses from the terrestrial ecosystem. According to our study, the total anthropogenic carbon emissions from the construction sector increased from 3,905×10(4) to 103,721.17×10(4) t from 1995 to 2010, representing 27.87%-34.31% of the total carbon emissions from energy consumption in China. Indirect carbon emissions from other industrial sectors induced by the construction sector represented approximately 97% of the total anthropogenic carbon emissions of the sector. These emissions were mainly concentrated in seven upstream industry sectors. Based on our assumptions, built-up land expansion caused 3704.84×10(4) t of carbon storage loss from vegetation between 1995 and 2010. Cropland was the main built-up land expansion type across all regions. The study shows great regional differences. Coastal regions showed dramatic built-up land expansion, greater carbon storage losses from vegetation, and greater anthropogenic carbon emissions. These regional differences were the most obvious in East China followed by Midsouth China. These regions are under pressure for strong carbon emissions reduction.