Time filter

Source Type

Yuan Y.,CAS Institute of Geographical Sciences and Natural Resources Research | Li B.,CAS Institute of Geographical Sciences and Natural Resources Research | Gao X.,CAS Institute of Geographical Sciences and Natural Resources Research | Liu H.,Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application | And 3 more authors.
Frontiers of Earth Science | Year: 2015

Net area change analysis can dramatically underestimate total change of land cover, even sometimes seriously misinterpret ecological processes of the ecosystem, especially in arid or semiarid zones. In this paper, a suite of indices are presented to characterize land-cover swaps that may seriously damage the ecosystem in arid or semiarid zones, based on swap-change areas extracted from remotely sensed images. First, swap percentage of total area and swap intensity of total changes were used to determine the status of land-cover swap change in an area. Then, dominated swap category and individual swap-change intensity for a land-cover category were used to determine flagged land-cover swap-change categories. Finally, swap-change mode and Pielou’s index were used to determine the land-cover swap-change processes of dominant categories. A case study is conducted using this approach, based on two land-cover maps in the 1980s and 2000 in Naiman Qi, Tongliao City, Inner Mongolia, China. This study shows that the approach can clearly quantify the severity and flagged classes of land-cover swap-change and reveal their relationship with ecological processes of the ecosystem. These results indicate that the approach can give deep insights into swap change, which can be very valuable to land-cover policy making and management. © 2015 Higher Education Press and Springer-Verlag Berlin Heidelberg

Xu F.-X.,Fudan University | Yang K.,China National Environment Monitoring Center | Wang Q.,China National Environment Monitoring Center | Zhao X.,China National Environment Monitoring Center | And 2 more authors.
Journal of Chinese Mass Spectrometry Society | Year: 2015

The linear quadrupole rodset has become a very important scientific instrument which can be used to produce quadrupolar electric field distribution. Because of the special property of ion motion in the linear quadrupole system, it has been widely used to build quadrupole mass filter, linear ion trap, quadrupole ion guide and many linear quadrupole related tandem mass spectrometer. All of these equipments have become an essential chemical and biological analytical technique with numerous applications in many fields, such as bioscience, chemistry, geology, environment, food safety and so on. In this paper, the theory of the linear quadrupole was briefly reviewed, including the kinetics of ion motion in quadrupole field, the effect of rodset structure on the field distribution, the effects of higher order electric field on the property of mass analysis and ion transmission. Then the latest research results in the field of quadrupole mass analyzer and quadrupole ion trap mass spectrometry were introduced. On the basis of this, the research direction of the quadrupole electrode system is prospected. ©, 2015, Editorial Board of Journal of Chinese Mass Spectrometry Society. All right reserved.

Qi Y.,China National Environment Monitoring Center | Qi Y.,Nanjing University | Wu J.,Arizona State University | Wu J.,Inner Mongolia University | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2013

Urbanization is an important aspect of land use and cover change, which profoundly affects ecosystem composition, structure and function as well as regional landscape pattern and processes. The rapid development of small- and medium-sized cities is a significant characteristic of global urbanization today, and is expected to remain so for decades in the future. During the last 50 years, the fastest growing cities in China are small-and medium-sized cities with populations ≤ 500 thousands. Thus, small-and medium-sized cities are important for regional social development and urbanization, which has significant impacts on the sustainability of the regions and the entire nation. In the past 20 years, because of the rapidly rising number of small-and medium-sized cities, their urbanization effects have received increasing attention. Understanding the generalities and idiosyncrasies of the urbanization patterns and processes of these cities is crucial for sustainable development. However, much of the current research on urbanization has focused primarily on the large cities with populations > 500 thousands. Few studies have investigated the complexity and dynamics of small-and medium-sized cities, including the relationship between urban landscape patterns and urban ecosystem functions. In this study, we selected 24 small-and medium-sized cities in Xinjiang and the Yangtze River Delta region to quantify landscape change and underlying driving forces in the two regions using a comparative approach. Based on the results of our study, we concluded: (1) In the two regions, urban land type had the highest growth rate with a mean annual increase of > 5%, suggesting a rapid urbanization process from 1986 to 2000. However, the specific changes of land use and land cover types differed in the two regions. In the Yangtze River Delta, cropland declined in area significantly more than other types, with a mean annual decrease rate of 62. 87 km2. In the Xinjiang region, the areas of unused land and grassland declined substantially during the study period. The mean annual decrease rates of these two land-use types were 123. 6 km2 and 90. 2 km2, respectively. (2) The overall pattern of landscape change in the two regions was similar during the 15 years. The level of landscape fragmentation, landscape diversity, and patch shape complexity all increased. However, the urban landscape pattern among different cities in the Yangtze River Delta region became more homogeneous compared to the Xinjiang region. (3) Our comparison of the main forces driving landscape change in the two regions indicated that the changes in croplands contributed significantly to the changes in the overall landscape pattern of small-and medium-sized cities. In the Yangtze River Delta, the main driving forces of landscape change were associated with population growth and rural-to-urban migration of people. A large quantity of cropland was used for urban construction and became increasingly fragmented as urbanization unfolded. In contrast, the main driver of landscape change in the Xinjiang region was related predominantly to the increase in croplands due to population growth and immigration. In this case, the increased human activity resulted in the increase in cropland. Urban sprawl contributed relatively less to landscape pattern change in Xinjiang than in the Yangtze River Delta. In addition, the expansion of croplands not only took up a large amount of grassland resources, but also intensified land use on the grasslands, consequently leading to degradation of the grassland ecosystems. These findings provide useful information for dealing with ecological and environmental problems induced by rapid urbanization, and for sustainable development of small-and medium-sized cities in China. Further studies are needed to investigate the processes and mechanisms of how urbanization affects biodiversity and ecosystem services in these small-to medium-sized cities.

Li M.-S.,China National Environment Monitoring Center | Zhou L.,China National Environment Monitoring Center | Chen Y.-H.,China National Environment Monitoring Center | Li Q.,China National Environment Monitoring Center | Zhang J.-H.,China National Environment Monitoring Center
Huanjing Kexue/Environmental Science | Year: 2014

Economic structure adjustment is an important means to reduce the emissions of pollutants. For quantitative analysis of the effect of economic structure adjustment on the reduction of pollution emission, the country was divided into four sub-regions, eastern, northeastern, central and western, and the industry was divided into 39 sectors. Taking chemical oxygen demand (COD) as an example, the influences of regional structure and industry structure adjustment on total emission reduction and emission intensity were analyzed through building a model. The results showed that, in 2000-2010: (1)COD emissions in China were reduced from 1 445×104 t to 1 238×104 t, with a total emission of 14 950×104 t in 11 years, among which the emissions from eastern area occupied the largest proportion, accounting for 35.6%. (2)In the industrial COD emissions, emission from paper and paper products was the largest, accounting for 35.8% of the industrial COD emissions. (3) The economic structure changes in the four areas reduced the COD emissions by 420× 104 t, resulting in a decrease of 1.29% in COD emission intensity. (4)Industrial internal structure changes reduced the COD emissions by 533× 104 t, leading to a decrease of 3.1% in COD emission intensity. The research results have certain reference value in guiding the Chinese economic structure adjustment and achieving the targets of energy-saving and emission reduction.

Li M.-S.,China National Environment Monitoring Center | Sun Y.,China National Environment Monitoring Center | Chen Y.-H.,China National Environment Monitoring Center | Zhang J.-H.,China National Environment Monitoring Center
Huanjing Kexue/Environmental Science | Year: 2014

In order to explore the mutual influence between pollutant discharge and environment quality, relation models of pollutant discharge and environmental quality were established, and the relationship was divided into four types, low pollutant discharge-high environmental quality, high pollutant discharge-high environmental quality, high pollutant discharge-low environmental quality, and low pollutant discharge-low environmental quality. The evolution paths from one type into another were also discussed. The regional data in 2005 and 2010 was used to validate the pollutant discharge-environmental quality models. The results showed that most regions of China belonged to the high pollutant discharge-low environmental quality type, and the pollutant discharge-environmental quality type didn't vary too much during the 2005-2010 period. In the majority of provinces, the environmental quality index was higher than the pollutant discharge index, and the pollutant discharge quantity overflowed the environmental capacity. The reduction of pollutant discharge quantity should be the most important environmental problem in China. At present, China is in a critical period of environmental governance, and excessive disturbance from economic system to the environment system should be prevented. The results should be helpful for understanding the regional environmental quality situation, on the implementation of pollutant discharge reduction, and the improvement of environmental quality.

Loading China National Environment Monitoring Center collaborators
Loading China National Environment Monitoring Center collaborators