Guangzhou as the political, economic and cultural center of Southern China, the social economy has achieved rapid development and urban spatial structure changed dramatically after 30 years of reform and opening up. With the accelerated process of urbanization, environmental problems have become increasingly serious and urban heat island effect in many environmental problems are particularly prominent, causing more and more attention. In this study, Landsat-8 satellite data is used to inverse the 4 periods (October 2014, November 2014, January 2015 and October 2015) LST (land surface temperature) of Guangzhou. At the same time, the PM 2.5 monitoring data in the Landsat-8 satellite transit time will be collected according to the "Real Time Air Quality of Guangzhou" released by Guangzhou Environmental Monitoring. This study selected concentration of PM 2.5 monitoring data from 32 monitoring stations and interpolated the Guangzhou PM 2.5 concentration distributions through ordinary Kriging. Combined with LST and PM 2.5 concentration distributions in Guangzhou, determine the difference and correlation between PM 2.5 and LST by using statistical analysis software. The results showed that the LST and PM 2.5 concentration in old district just like Liwan, Yuexiu, Haizhu and new industrial park were significantly higher than that of Panyu, Conghua, Zengcheng and other new district. PM 2.5 concentration distribution trends and LST inversion results have a certain degree of correlation. Correction factor in regression analysis of sampling point (LST and PM 2.5 ) is greater than the threshold 0.8 which means a high degree of fit.
Artificial erosion is one of the typical artificial landscape degradation. Based on the support of GIS and RS and combined with field investigation data, the spatial distribution characteristics and landscape ecological impact degree of quarry were analyzed. There were 235 quarries in Zhuhai city, which concentrated on Sanzao town and Jingan town. According to buffer analysis, the quarries distribution had a obviously logarithm relationship with its distances from roads. 152 quarries with the area of more than 5000 m2 were assessed by landscape ecological impact degree (LEI) index. The results indicated that 9 quarries belonged to great influence level and 19 quarries belonged to strong influence on ecological environment.
Abstract As ozone pollution in the troposphere has become increasingly severe, more publications have focused on the emissions of biogenic volatile organic compounds (BVOCs), which are important precursors for ozone formation. However, most reviews describe the research status of certain specific aspects rather than holistically quantifying research hotspots and development trends, which limit the overall understand of BVOCs emissions. In this paper, bibliometric analysis was used to study the publication output and hotspots of BVOCs emissions research from 1991 to 2019. Then, the evolutionary trends in BVOCs emission sources research were explored further by combining evolution tree and Markov chain methods. We found that the USA consistently took the leading position in BVOCs research, which cooperated with Germany and China closely. Environmental Science & Ecology and Meteorology & Atmospheric Sciences were the most active research subject categories. Current literatures mainly focused on the plant stress response, the atmospheric chemistry of BVOCs emissions, and their measurement by field determination and model-based estimation. Most publications researched BVOCs emitted by plants, in particular Pinaceae, while the growth of publications researching microbial volatile organic compounds (mVOCs) was slow. In the future, we should consider the role of mVOCs and combine field observation with model estimation to improve the credibility of BVOCs estimates and provide scientific guidance for air pollution control. And, with climate change, it will be worth exploring the driving variables of BVOCs emissions and its interaction in earth system to unravel how BVOCs emissions will respond to the changing earth system.
With the combination of gradient analysis and quantitative analysis of landscape pattern,and by changing the transect width and research step,the extent effect of landscape gradient analysis of an urban-rural transect were studied.The results showed that the landscape gradient analysis of the urban-rural transect was scale-dependent,and the effect of transect width was greater than that of research step.Research step mainly affected the fluctuation degree of each landscape index along transect,and it was appropriate for the transect to be divided equally into 20 samples.There existed critical values for transect width.When the transect width was beyond the values,the fluctuation trend of each index along transect would be varied.Furthermore,different landscape metrics responded differently to the same transect.The percent coverage and edge density of each class,as well as the Shannon's diversity index of landscape,showed significant gradient characteristics,while patch density and mean patch fractal dimension were in adverse.
Urban green space has been implicated in shaping airborne microbes, but there is an only rudimentary understanding of the key factors of urban green space affecting the composition and structures of airborne microbes. Here, we selected 40 urban sites based on stratified random sampling design and investigated the effects of multiple factors including landscapes, plant, soil, and anthropogenic factors on airborne microbial communities, especially bacterial and fungal pathogens. Bacterial and fungal communities in the control area with lower greenness were significantly (P < 0.05) different from those in other areas with a gradient of green space. The relative abundance of bacterial and fungal pathogens significantly (P < 0.05) decreased with increasing greenness. Other than soil thickness, soil type, slope position, and population density, plant species considerably contributed to the shift in the composition and abundance of potential bacterial and fungal pathogens. A significantly (P < 0.05) reduced abundance of bacterial and fungal pathogens was observed in areas with >30% masson pine. Together, these results provide insights into the importance of green space for providing health benefits for city dwellers by reducing pathogens in air, as well as providing support for the inclusion of plant species in the management of urban green space to reduce exposure risk of airborne pathogens.
Urbanization transforms landscapes from natural ecosystems to configurations of impervious surfaces and green spaces, leading to urban heat island effects that impact health and ecosystem sustainability. This study in Xiamen City, China, categorizes urban areas into functional zones, employs Random Forest and Stepwise Regression models to assess thermal differences, and proposes optimization measures for the building–green space landscape. The optimization involves altering the characterization of the building–green space landscape pattern. Results indicate: (1) due to the spatial heterogeneity of the building–green space landscape pattern in different functional zones, the surface temperature also shows strong spatial heterogeneity in different functional zones; (2) different optimization measures for the building–green space pattern are needed for different functional zones; taking the urban residential zone as an example, the Normalized Difference Vegetation Index (NDVI) in the hot spot area can be adjusted according to the value range of the cold spot area; (3) considering the solar radiation process, Sun View Factor (SunVF) plays an important role in indicating the change in surface temperature in the commercial service area, and as SunVF increases, the surface temperature of the functional zone tends to rise. This research offers insights into urban thermal environment improvement and landscape pattern optimization.
Based on GIS with landscape pattern analyst software (Patch Analyst 2.0),diversity and fragmentation of cultivated land in Guangzhou city were analysis in this paper.Spatial distribution pattern on cultivated land resources was main controlled by landform types,and was disturbed by urbanization processes and man-made factors in a certain extent.Results indicated that the grade of diversity and fragmentation were high in hill area in north of Guangzhou city.It is very important to protect the diversity and integrality of cultivated land for land resources development and use rationally.
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