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The spinel ZnFe2O4 specimens were obtained via a hydrothermal and a ceramic method, respectively, and their structural and magnetic properties were comparatively studied. It was found that all the specimens exhibited a single-phase and mixed spinel structure. The magnetism of specimens synthesized via the hydrothermal method is obviously greater than that of specimen prepared via the ceramic method. This can be ascribed to the occupancy of Fe ions resulted from the loss of Zn during the hydrothermal process. more...

Wetland is one of the three major ecosystems on the earth and has fundamental ecological functions and plays an irreplaceable role in serving biological survival and human development. Considering the characteristics of five types of wetlands, this study constructed a wetland ecological health evaluation indicator system using a wide variety of data from statistical report, field sampling, remote sensing, and questionnaire survey. In this study, we have selected 13 indicators (related to water, soil, biological, landscape and social factors) for ecological health evaluation of 19 wetlands in Beijing-Tianjin-Hebei region of China which have national importance. The detailed analysis shows a comprehensive health index of 5.53. There was significant spatial heterogeneity in the health status of the 19 wetlands in this region. The evaluation results and analysis provides scientific services for developing reasonable and targeted wetland protection and utilization policies of wetlands. more...

Aerosol pollution has become an increasingly serious problem in China. Among the multiple factors causing aerosol pollution, wildfires in China are occurring more frequently and have gradually become one of the most important contributing factors. However, little is known about their potential causality trends or spatial characteristics. In this research, satellite data of fire events and atmospheric aerosol datasets from 2001 to 2016 were applied in the geographical, statistical “Geodetector model” (GDM) to better understand their causal relationship. From long term observation data in China, we found that the increase in wildfires over the study period greatly enhanced their impacts on the aerosol optical depth (AOD) in recent years. The contribution of burning areas to AOD was 18.29% in 2001 and increased to 38.94% in 2016, and the contribution of fire radiative power (FRP) was 18.80% in 2001 and became 36.05% in 2016. In addition, seasonal research suggested that wildfires contributed rapidly to aerosol pollution, usually from April to September. The regional results in China showed that wildfires can be a relatively dominant factor for aerosol pollution in the southern regions, so that more importance should be attached to the complicated pollution conditions. Overall, our findings highlight the causal effects of wildfires on atmospheric aerosol pollution in China. We suggest that the rising contributions of wildfires to AOD in China should be noticed, and attention should be given to adaptions to local conditions regarding wildfires and aerosol pollution management. more...

Sanjiangyuan region, which located in the north of Qinghai-Tibet Plateau in China, is characterized by an extreme environment and is subject to the impacts of climate change and intense human activities. To protect the eco-environment in Sanjiangyuan, the Sanjiangyuan National Nature Reserve (SNNR) was established in 2000, and an ecological project was initiated in 2005. Comprehensive and quantitative evaluation of the eco-environmental vulnerability (EV) and analysis of the long-term dynamic changes in the region are extremely important for understanding eco-environmental change and assessing protection effectiveness, however rarely found in previous research. The aim of this study is to develop a method to assess EV and analyse the dynamic change in Sanjiangyuan region for years 1990, 2000 and 2010. In the first phase of the study, an integrated evaluation method based on Fuzzy Analytic Hierarchy Process (FAHP) was developed. This phases included: ■ development of the evaluation hierarchical structure and selection criteria; ■ data collection and processing; ■ evaluation criteria normalization; ■ determination of the related importance of the criteria; ■ criteria weighting calculation, and; ■ linear weighted combination. In the second phase of the study, the developed methodology was applied to assess the EV in the Sanjiangyuan region for the years 1990, 2000, and 2010, and to document the dynamic change. In the third phase, a series of integrated regional EV grades were used to analyse the EV change both within and outside of SNNR. The results showed that: 1) EV in the whole Sanjiangyuan region was distributed as a high/low gradient that trends west to east in all three study periods; 2) the dynamic change of EV in Sanjiangyuan region as a whole showed a moderate reduction during 1990–2000, a sizeable and extensive decrease during 2000–2010; and, 3) during the 2000–2010 period, ecological environment change magnitude was significantly better within the Sanjiangyuan National Nature Reserve than for the unprotected areas of the region. The proposed method is relatively easy to implement and could also be applied to other study regions. However, the method could be further improved by reducing some subjective elements. more...

To address devastating land desertification and soil erosion and to improve human well-being, central government in China has implemented a number of ecological restoration programs. It is essential to rigorously monitor the dynamic of vegetation activity and evaluate the effectiveness of these programs, not only to provide scientific support for ecosystem monitoring in arid and semi-arid region, but also to assess the efficiency of ecological restoration policy. Taking Inner Mongolia as study area, we used 13 years (2000–2012) of both climatic data and MODIS NDVI data to (1) assess the spatiotemporal vegetation dynamic and map areas of significant vegetation restoration and degradation, (2) analyze the impacts of climatic changes on vegetation activity and map areas where vegetation activity dynamic was significantly affected by climatic change, (3) map main driving forces of significant vegetation restoration or degradation, (4) validate the zones where vegetation significant restoration were mainly impacted by ecological restoration programs with vegetation fractional cover data in 2000 and 2012. Results showed an overall greening (15.38% significant NDVI increasing) and partial degradation (1.64% significant NDVI decreasing) in Inner Mongolia. It was estimated that annual precipitation most strongly and significantly limited vegetation growth over 45.1% of Inner Mongolia, whereas sunlit hours significantly limited growth over 3.37% and air temperature significantly over 0.73% of Inner Mongolia. Among the 15.38% significant greening region, 5.86% was caused by climatic changes, 5.67% was caused by ecological restoration programs, and the other 3.8% was caused by multi-factors. Among the 1.64% significant degradation region, 0.17% was caused by climatic changes and other 1.47% can be explained by human activities, such as population growth and city expansion. more...

A severe prolonged regional haze episode occurred over the Yangtze River Delta (YRD) from 2 to 14 December 2013. In this paper, we have discussed the probable cause of haze episode and aerosol characteristics. Analysis of visibility and meteorological parameters suggest that the meteorological conditions play a very important role in the accumulation of aerosol particles that cause haze. The height of the planetary boundary layer (PBL) is considered as one of the key factors together with other factors in the haze formation. The Principal Component Analysis (PCA) clearly shows accumulation process of air pollutants from vehicular, industrial and anthropogenic sources are major contributors for the haze formation. The aerosol optical properties (aerosol optical depth – AOD, Angstrom exponent – α and Ultra Violet Aerosol Index – UVAI) are analyzed to study the temporal and spatial variations of aerosol loadings. The results show concentrations of fine mode particles during the haze episode, the dust could have been also entered in the region from the northwestern China. Analysis of vertical aerosol profiles indicate that dust aerosols concentrated in the lower part of the haze layers. more...

Multi-satellite sensors are capable of monitoring transport and characteristics of dust storms and changes in atmospheric parameters along their transport. The present paper discusses aerosol optical properties and meteorological parameters during major dust storm events occurred in the period 2005–2010 over Beijing, China. The back trajectory model shows that the dust is transported from the Inner Mongolia and Mongolia arid regions to Beijing. High aerosol optical depth (AOD) at the wavelength 675 nm and low Angstrom exponent (AE) values in the wavelength 440–870 nm are observed during dusty days. The aerosol size distribution (ASD) in coarse mode shows a large increase in the volume during dusty days. The single scattering albedo (SSA) increases with higher wavelength on dusty days, and is generally found to be higher compared to the days prior to and after the dust events, indicating the presence of high concentrations of scattering particles due to dust storm events. The physico-chemical properties of aerosols during dusty and non dusty days show distinct characteristics as reflected from the changes in the real and imaginary parts of refractive index (RI). In addition, the CO volume mixing ratio (COVMR) from Atmospheric Infrared Sounder (AIRS) shows a pronounced decrease on dusty days, while the H 2 O mass mixing ratio (H 2 OMMR) shows enhanced signal. Furthermore, enhanced level of water vapor (WV) using Moderate Resolution Imaging Spectroradiometer (MODIS) data is also observed in and around Beijing over the dust storms track. more...

Using one year of Aerosol Optical Depth (AOD) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite and particular matter (PM) contents measured at eleven sites located mostly in the eastern China in 2007, the relationship between columnar AOD and hourly and daily average (DA) PM were established. The peak AOD observed from MODIS was generally consistent with the surface PM measurements in eastern China, where Zhengzhou had the maximum annual mean PM 10 of 182.1 μg m −3 , while Longfengshan had the minimum annual mean of 38.1 μg m −3 . Ground level observations indicated that PM concentration varies widely across different regions, which was mainly due to the difference in weather conditions and anthropogenic emissions. The coarse particles accounted for the main air pollution in Zhengzhou and Benxi whiles the fine particles, however, were the main constituents in other sites. Results showed that MODIS AOD (averaged over the box of 5 × 5 and 3 × 3 pixels) had a better positive correlation with the coincident hourly average (HA) PM concentration than with DA due to diurnal variation in PM mass measurements. After correcting AOD for relative humidity (RH), the correlation did not improve significantly, suggesting that the RH was not the main factor affecting the correlation of PM with AOD. The statistical regression analysis between MODIS AOD and PM mass suggested that the satellite-derived AOD is a useful tool for mapping PM distribution over large spatial domains. more...

A wide variety of algorithms have been developed to monitor aerosol burden from satellite images. Still, few solutions currently allow for real-time and efficient retrieval of aerosol optical thickness (AOT), mainly due to the extremely large volume of computation necessary for the numeric solution of atmospheric radiative transfer equations. Taking into account the efforts to exploit the SYNergy of Terra and Aqua Modis (SYNTAM, an AOT retrieval algorithm), we present in this paper a novel method to retrieve AOT from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images, in which the strategy of block partition and collective communication was taken, thereby maximizing load balance and reducing the overhead time during inter-processor communication. Experiments were carried out to retrieve AOT at 0.44, 0.55, and 0.67 μm of MODIS/Terra and MODIS/Aqua data, using the parallel SYNTAM algorithm in the IBM System Cluster 1600 deployed at China Meteorological Administration (CMA). Results showed that parallel implementation can greatly reduce computation time, and thus ensure high parallel efficiency. AOT derived by parallel algorithm was validated against measurements from ground-based sun-photometers; in all cases, the relative error range was within 20%, which demonstrated that the parallel algorithm was suitable for applications such as air quality monitoring and climate modeling. more...