Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Th...Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.展开更多
Regional soil erosion surveys are the first step of soil conservation planning.Grid and sampling ap-proaches are commonly used for soil erosion surveys at the regional scale.With the grid approach,the region is divide...Regional soil erosion surveys are the first step of soil conservation planning.Grid and sampling ap-proaches are commonly used for soil erosion surveys at the regional scale.With the grid approach,the region is divided into grids(e.g.,1 km × 1 km),and the soil erosion rate of each grid was calculated.With the sampling approach,a small portion of the area(typically 4%or less)was taken and then the soil erosion rate was calculated.Based on the above calculation,both approaches evaluated the soil erosion area(which is the area where the soil erosion rate is greater than the soil loss tolerance(t))and its distribution in the whole region.The purpose of this paper is to compare the assessment results of the two approaches and analyse their practicality using Yunyang County,Chongqing,China(area is 3636 km^(2)).The soil erosion rate,percentage of soil erosion area(PSEA,which is the ratio of the area where the soil erosion rate is greater than the soil loss tolerance(t)to the area of the total study region)and its spatial distribution were compared between the two approaches.The results showed that the grid approach overestimated the average soil erosion rate and PSEA overall for all 33 sample units and the whole region in comparison to the sampling approach.The sampling approach can yield a reasonable spatial distribution of the soil erosion rate in the whole region.In addition,the soil erosion regions were more clustered than those using the grid approach,which can be more suitable for soil conservation planning.Therefore,the sampling approach is an efficient and practical approach in regional soil erosion surveys.The results can provide insights into regional soil erosion surveys.展开更多
区域综合能源系统(regional integrated energy systems,RIES)集成了冷、热、电、气等多种能源形式,是现代能源供给体系的发展方向,有利于实现区域内能源的综合利用与管理,而多能流的计算是RIES分析的基础。考虑RIES的不确定因素,提出...区域综合能源系统(regional integrated energy systems,RIES)集成了冷、热、电、气等多种能源形式,是现代能源供给体系的发展方向,有利于实现区域内能源的综合利用与管理,而多能流的计算是RIES分析的基础。考虑RIES的不确定因素,提出一种概率多能流计算方法。首先建立多能流计算模型,包含供冷系统、供热系统、电力系统及天然气系统的方程,使用牛顿拉夫逊法进行统一求解;其次,讨论了冷、热、电系统平衡节点的设置与对应的计算条件,包括多种能源网络平衡节点为相同物理节点的情况;在此基础上,结合冷、热、电、气负荷及间歇性能源的概率模型,基于拉丁超立方采样计算RIES的概率多能流,并计及随机变量之间的相关性;最后以一个小型RIES为算例进行了分析,验证了所提方法的有效性。展开更多
基金Supported by National Natural Science Foundation of China (Grant No. 40775078)National Non-profit Research Project to Serve the Public Interest (Grant No. GYHY200806026)International S & T Cooperation Program of MOST(Grant No. 2007DFA20650)
文摘Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.
基金This work was supported by the National Key R&D Project of China(2021YFD1500704).
文摘Regional soil erosion surveys are the first step of soil conservation planning.Grid and sampling ap-proaches are commonly used for soil erosion surveys at the regional scale.With the grid approach,the region is divided into grids(e.g.,1 km × 1 km),and the soil erosion rate of each grid was calculated.With the sampling approach,a small portion of the area(typically 4%or less)was taken and then the soil erosion rate was calculated.Based on the above calculation,both approaches evaluated the soil erosion area(which is the area where the soil erosion rate is greater than the soil loss tolerance(t))and its distribution in the whole region.The purpose of this paper is to compare the assessment results of the two approaches and analyse their practicality using Yunyang County,Chongqing,China(area is 3636 km^(2)).The soil erosion rate,percentage of soil erosion area(PSEA,which is the ratio of the area where the soil erosion rate is greater than the soil loss tolerance(t)to the area of the total study region)and its spatial distribution were compared between the two approaches.The results showed that the grid approach overestimated the average soil erosion rate and PSEA overall for all 33 sample units and the whole region in comparison to the sampling approach.The sampling approach can yield a reasonable spatial distribution of the soil erosion rate in the whole region.In addition,the soil erosion regions were more clustered than those using the grid approach,which can be more suitable for soil conservation planning.Therefore,the sampling approach is an efficient and practical approach in regional soil erosion surveys.The results can provide insights into regional soil erosion surveys.
文摘区域综合能源系统(regional integrated energy systems,RIES)集成了冷、热、电、气等多种能源形式,是现代能源供给体系的发展方向,有利于实现区域内能源的综合利用与管理,而多能流的计算是RIES分析的基础。考虑RIES的不确定因素,提出一种概率多能流计算方法。首先建立多能流计算模型,包含供冷系统、供热系统、电力系统及天然气系统的方程,使用牛顿拉夫逊法进行统一求解;其次,讨论了冷、热、电系统平衡节点的设置与对应的计算条件,包括多种能源网络平衡节点为相同物理节点的情况;在此基础上,结合冷、热、电、气负荷及间歇性能源的概率模型,基于拉丁超立方采样计算RIES的概率多能流,并计及随机变量之间的相关性;最后以一个小型RIES为算例进行了分析,验证了所提方法的有效性。
