Zhaoning Gong

Topographic Correction of ZY-3 Satellite Images and Its Effects on Estimation of Shrub Leaf Biomass in Mountainous Areas

The availability of ZY-3 satellite data provides additional potential for surveying, mapping, and quantitative studies. Topographic correction, which eliminates the terrain effect caused by the topographic relief, is one of the fundamental steps in data preprocessing for quantitative analysis of vegetation. In this paper, we rectified ZY-3 satellite data using five commonly used topographic correction models and investigate their impact on the regression estimation of shrub forest leaf biomass obtained from sample plots in the study area. All the corrections were assessed by means of: (1) visual inspection (2) reduction of the standard deviation (SD) at different terrain slopes (3) correlation analysis of different correction results. Best results were obtained from the Minnaert+SCS correction, based on the non-Lambertian reflection assumption. Additional analysis showed that the coefficient correlation of the biomass fitting result was improved after the Minnaert+SCS correction, as well as the fitting precision. The R2 has increased by 0.113 to reach 0.869, while the SD (standard deviation) of the biomass dropped by 21.2%. Therefore, based on the facts, we conclude that in the region with large topographic relief, the topographical correction is essential to the estimation of the biomass.

Fine Particulate Matter Pollution and Hospital Admissions for Respiratory Diseases in Beijing, China

Fine particulate matter has become the premier air pollutant of Beijing in recent years, enormously impacting the environmental quality of the city and the health of the residents. Fine particles with aerodynamic diameters of 0~0.3 μm, 0.3~0.5 μm, and 0.5~1.0 μm, from the yeasr 2007 to 2012, were monitored, and the hospital data about respiratory diseases during the same period was gathered and calculated. Then the correlation between respiratory health and fine particles was studied by spatial analysis and grey correlation analysis. The results showed that the aerial fine particulate matter pollution was mainly distributed in the Zizhuyuan sub-district office. There was a certain association between respiratory health and fine particles. Outpatients with respiratory system disease in this study area were mostly located in the southeastern regions (Balizhuang sub-district office, Ganjiakou sub-district office, Wanshoulu sub-district office, and Yongdinglu sub-district office) and east-central regions (Zizhuyuan sub-district office and Shuangyushu sub-district office) of the study area. Correspondingly, PM1 (particulate matter with aerodynamic diameter smaller than 1.0 um) concentrations in these regions were higher than those in any other regions. Grey correlation analysis results showed that the correlation degree of the fine particle concentration with the number of outpatients is high, and the smaller fine particles had more obvious effects on respiratory system disease than larger particles.

Ecological environment effect analysis of Wetland change in Beijing region using GIS and RS

By utilizing TM/ETM+ remote sensing images from 1984 to 2004 as the major data sources, combining with the field survey to get the rule of dynamic process of Beijing wetland ecosystem, this paper systematic analyzed the hydrology, soil, plant condition of the typical wetland area- Widgeon Lake Wetland Natural Reserve in Beijing. And the results are as follows: In recent years, wetland areas were sharply reduced by half. The negative ecological effects around wetland areas have a close relationship with the deterioration of wetland resources. Salinized area had increased every year and reached to a head in 2004, which accounted for about 21.79 square kilometers. The serious and medium level salinity areas were in the majority in region. Due to the soil salinization, the marsh vegetation species changed to the mesophytic, xeromorphic and salt tolerable ones. Along with the continuously shrinking of water area, wetland dominated the low coverage. The area of medium to high and high coverage in 2004 reduced 71.09 percent and 99.26 percent respectively compared with those in 1998. The regional vegetation cover had shown the degradation trend. Accordingly the soil conservation function of vegetation weakened and soil fertility declined. The cold-humid effect of wetland had been impaired for the breakage of wetland environment in recent years, which led to the drying and warming tendency of regional microclimate. The phenomenon of the decrease amount of regional daily evapotranspiration proved that the climate was drying and warming. The serious disequilibrium between source and sink landscape in every sub-watershed of wetland was an important factor to cause non-point source pollution. The nonpoint source pollution in upper reaches of wetland had caused the high eutrophic water in recent years. From the field water quality monitor we could find the main contaminations were total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD) and fluorid (F). Water quality has reduced up to IV or V grade. The wetland landscape shape fragmentation indexes were all over 0.99 from 1998 to 2002, which showed the impacts of human disturbance on landscape was intensive, the wetland landscape had suffered a serious destruction and the ecology was instability. Based on the above analysis, the regional ecological negative effects were closely connected with the decrease of wetland resources. We should bring forward corresponding effective protection and utilization measures and give the scientific basis for the restoration of wetland resources.

Correlation analysis between vegetation coverage and climate drought conditions in North China during 2001–2013

Climate change is one of the most important factors that affect vegetation distribution in North China. Among all climatic factors, drought is considered to have the most significant effect on the environment. Based on previous studies, the climate drought index can be used to assess the evolutionary trend of the ecological environment under various arid climatic conditions. It is necessary for us to further explore the relationship between vegetation coverage (index) and climate drought conditions. Therefore, in this study, based on MODIS-NDVI products and meteorological observation data, the Palmer Drought Severity Index (PDSI) and vegetation coverage in North China were first calculated. Then, the interannual variations of PDSI and vegetation coverage during 2001–2013 were analyzed using a Theil-Sen slope estimator. Finally, an ecoregion perspective of the correlation between them was discussed. The experimental results demonstrated that the PDSI index and vegetation coverage value varied over different ecoregions. During the period 2001–2013, vegetation coverage increased in the southern and northern mountains of North China, while it showed a decreasing trend in the Beijing-Tianjin-Tangshan City Circle area and suburban agricultural zone located in Hebei Province and Henan Province). Over 13 years, the climate of the northeastern part of North China became more humid, while in the southern part of North China, it tended to be dry. According to the correlation analysis results, 73.37% of North China showed a positive correlation between the vegetation coverage and climate drought index. A negative correlation was observed mainly in urban and suburban areas of Beijing, Tianjin, Hebei Province, and Henan Province. In most parts of North China, drought conditions in summer and autumn had a strong influence on vegetation coverage.

Driving forces analysis of reservoir wetland evolution in Beijing during 1984–2010

The reservoir wetland, which is the largest artificial wetland in Beijing, constitutes one of the important urban ecological infrastructures. Considering two elements of natural environment and socio-economy, this paper established the driving factor indexing system of Beijing reservoir wetland evolution. Natural environment driving factors include precipitation, temperature, entry water and groundwater depth; social economic driving factors include resident population, urbanization rate and per capita GDP. Using multi-temporal Landsat TM images from 1984 to 2010 in Beijing, the spatial extent and the distribution of Beijing reservoir wetlands were extracted, and the change of the wetland area about the three decade years were analyzed. Logistic regression model was used to explore for each of the three periods: from 1984 to 1998, from 1998 to 2004 and from 2004 to 2010. The results showed that the leading driving factors and their influences on reservoir wetland evolution were different for each period. During 1984-1998, two natural environment indices: average annual precipitation and entry water index were the major factors driving the increase in wetland area with the contribution rate of Logistic regression being 5.78 and 3.50, respectively, and caused the wetland growth from total area of 104.93 km2 to 219.96 km2. From 1998 to 2004, as the impact of human activities intensified the main driving factors were the number of residents, groundwater depth and urbanization rate with the contribution rate of Logistic regression 9.41, 9.18, and 7.77, respectively, and caused the wetland shrinkage rapidly from the total area of 219.96 km2 to 95.71 km2. During 2004–2010, reservoir wetland evolution was impacted by both natural and socio-economic factors, and the dominant driving factors were urbanization rate and precipitation with the contribution rate of 6.62 and 4.22, respectively, and caused the wetland total area growth slightly to 109.73 km2.

Dustfall Heavy Metal Pollution During Winter in North China

In order to study heavy metal pollution in dustfall during Winter in North China, forty-four dustfall samples were collected in North China Region from November 2013 to March 2014. Then forty trace elements content were measured for each sample by inductively coupled plasma-mass spectrometry. Finally, the contamination characteristics of the main heavy metals were studied through a multi-method analysis, including variability analysis, Pearson correlation analysis and principal component analysis. Results showed that the relative contents of cadmium (Cd), zinc (Zn), copper (Cu), bismuth (Bi), lead (Pb) exceeded the standards stipulated in Chinese soil elements background values by amazing 4.9 times. In this study, conclusions were drawn that dustfall heavy metal pollution in the region was mainly caused by transport pollution, metallurgy industrial pollution, coal pollution and steel industrial pollution.

A Preliminary Study of Urban Airborne Inhalable Particle Spatial Distribution and their Mechanism in Beijing using RS and GIS

The spatial distribution of PM0.3 PM0.5 and PM1.0 concentration are simulated by monitoring data obtained from 73 air sampling stations in Beijing urban city and Kriging techniques. By taking streets and towns as the basic spatial analysis unit, some factors are mapped influencing urban airborne inhalable particulates pollutions such as urban ground surface types, population density based on GIS and RS. The correlation between PM0.3 PM0.5 and PM1.0 and their influencing factors are quantitatively evaluated by using GIS multifactor integrated analysis and GIS overlay of ranked data layers. Meanwhile, according to the concentration of particles in different weather conditions showing different regularity, we also analysis possible meteorological factors such as temperature (in degC), relative humidity (in %) and wind speed (in m/s). This article discovers the key factors and their mechanism. At last, several constructive strategies are delivered.

Evolution Characteristics of Wetland in Beijing and Its Driving Factors Analysis

Supported by remote sensing and GIS technology, using Multi-temporal TM images from 1984a to 2008a in Beijing, the dynamic evolution characteristics of wetland were analyzed and driving factors were explored. The result shows: the total wetland area increased during the period from 1984a to 1996a, the wetland area in 1996a had the maximum value, totally 605. 67km2. while it obviously declined at the annual average rate 6.7% from 1996a to 2004a, the wetland area in 2004a was just 285.27 km2, which accounting for 47.1% of the wetland area in 1996a. Wetland had taken the dominant shrinking trend and its ecological function had degenerated gradually. The total wetland area had appreciably increased after 2006a, reaching to 318.39km2 in 2008a. It was classified to natural wetland and artificial wetland, natural wetland means river wetland and artificial wetland included reservoir wetland, pond and paddy field wetland, artificial canal wetland and city lake wetland. The proportion of artificial wetland area was lager than natural wetland, which played the ascendant function, accounting for about 70.95 to 86.01 percents in area. Wetland area increased from 1984a to 1996a mainly because of adequate precipitation; while the total wetland area declined from 1996a to 2004a for both natural elements and artificial reasons. Natural reasons included continuous dry climate, higher transpiration and decrease of water inflow from upriver. With the urbanization process acceleration, the population increased 1.52 times between 1984a and 2008a, which further lead to the wetland area loss and water resource consumptions. The total area of wetland in 2006a and 2008a increased appreciably as a result of the implement of positive policy and precipitation’s increase.

Appraisal of Beijing Wetlands Water Purification Value

Wetland is a kind of land resources and also a kind of ecological environment, it play more important role in people daily lives. Wetland has the vital role in the ecosystem such as storage of water, transformation of nutrients, especially its water purification function, which has important economy and ecological value. The wetlands water purifies mainly aims at nitrogen and phosphorus which causes water body eutrophication pollutant, the wetlands together with the soil, the microorganism and vegetation removes the pollutant. This research mainly aims at the economic value of Beijing wetlands water quality to carry on the appraisal, according to Beijing wetland division standard, through to the different types of wetlands field survey, finally identifying the type of water purification is: The rivers wetlands, the water reserve wetlands, the marsh wetlands, and select 5 typical wetlands areas to take the water quality sampling area, finally applies the type the value of water purification unit area applied to the corresponding types of wetlands, thus obtains Beijing wetlands water purification value.

Study of urban heat island based on remote sensing in Beijing-capital zone

The paper focused on spatial and temporal distribution of thermal environment by Land Surface Temperature(LST) and brightness temperature retrieved from ASTER and Landsat TM/ETM in Beijing-capital zone, and analyzing scale effect of multi-resolution LST data (LST retrieved by ASTER and MODIS LST product)with the variety of landuse and NDVI. The result showed that the UHI phenomena had increasing tendency. LST waved with difference of the landuse, the highest was in bare-land, and the lowest was in water. Green island was composed mainly by forest and water, while heavy heat island and serious heat island was mainly composed by built-up and bare-land. The linear equation with a strong negative relationship between means of NDVI and means of LST( ASTER retrieval LST and MODIS LST product) associated with the five cover types has been established. Cross-validation among the LST images retrieved from ASTER and MODIS LST product are reliable. The different spatial resolution of the thermal sensors can be used in urban studies demanding different levels of details. The MODIS thermal sensor can be used for the overview of urban thermal environment. The ASTER, with its TIR 90-m resolution, can be used for more accurate monitoring thermal patterns.