为研究城市形态和地表性质对城市地表热岛效应的影响,以西安市为例,基于Landsat8遥感影像和建筑矢量数据,采用局地气候分类(Local climate zone,LCZ)方法,对主城区进行LCZ划分.通过Landsat8遥感影像反演夏季地表温度,研究不同类型LCZ内...为研究城市形态和地表性质对城市地表热岛效应的影响,以西安市为例,基于Landsat8遥感影像和建筑矢量数据,采用局地气候分类(Local climate zone,LCZ)方法,对主城区进行LCZ划分.通过Landsat8遥感影像反演夏季地表温度,研究不同类型LCZ内地表温度的分布特征,同时选取14个地块分析地表热岛强度,通过计算建成区LCZ的城市形态参数分析城市形态对地表热岛效应的影响,采用的参数包括:建筑密度(Building surface fraction,BSF)、绿地率(Ratio of green space,GSP)以及下垫面粗糙度(Height of roughness elements,HRE).结果表明:建成区LCZ地表温度整体高于地表性质LCZ,但温度变化更稳定;建成区LCZ内,高密度的建筑区域地表温度高于低密度区域;地表性质LCZ内,水体温度最低,3种植被型LCZ地表温度低于其余两类LCZ,裸地温度最高;建成区LCZ地块内,高密度的高层建筑和较高的绿化率能够降低地表温度,缓解地表热岛强度;地表性质LCZ地块中水体和林地的地表热岛强度较低.在城市规划中合理的增加水体和绿化的布置,降低建筑密度同时在室外人流密集的区域设置遮阳设施将有利于缓解地表热岛效应.展开更多
The contamination and environmental risk assessment of the toxic elements in sediments from the middle-downstream (Zhuzhou-Changsha section) of the Xiangjiang River in Hunan Province of China were studied. The results...The contamination and environmental risk assessment of the toxic elements in sediments from the middle-downstream (Zhuzhou-Changsha section) of the Xiangjiang River in Hunan Province of China were studied. The results show that As, Cd, Pb and Zn are major contaminants in sediments, and average concentrations of these elements significantly exceed both the Control Standards for Pollutants in Sludge of China (GB4284-84) for agricultural use in acidic soils and the effect range median (ERM) values. The average concentrations of As, Cd and Pb in the river water slightly exceed the limit of Surface Water Environment Quality Standard (GB3838-2002). The concentrations of As and Cr in depth profiles extensively change, but slight changes are observed in Pb and Zn. Cd and Zn in most sediment samples can easily enter the food-chain and bring possible ecotoxicological risk to organisms living in sediments according to the risk assessment code.展开更多
文摘为研究城市形态和地表性质对城市地表热岛效应的影响,以西安市为例,基于Landsat8遥感影像和建筑矢量数据,采用局地气候分类(Local climate zone,LCZ)方法,对主城区进行LCZ划分.通过Landsat8遥感影像反演夏季地表温度,研究不同类型LCZ内地表温度的分布特征,同时选取14个地块分析地表热岛强度,通过计算建成区LCZ的城市形态参数分析城市形态对地表热岛效应的影响,采用的参数包括:建筑密度(Building surface fraction,BSF)、绿地率(Ratio of green space,GSP)以及下垫面粗糙度(Height of roughness elements,HRE).结果表明:建成区LCZ地表温度整体高于地表性质LCZ,但温度变化更稳定;建成区LCZ内,高密度的建筑区域地表温度高于低密度区域;地表性质LCZ内,水体温度最低,3种植被型LCZ地表温度低于其余两类LCZ,裸地温度最高;建成区LCZ地块内,高密度的高层建筑和较高的绿化率能够降低地表温度,缓解地表热岛强度;地表性质LCZ地块中水体和林地的地表热岛强度较低.在城市规划中合理的增加水体和绿化的布置,降低建筑密度同时在室外人流密集的区域设置遮阳设施将有利于缓解地表热岛效应.
基金Project (20507022) supported by the National Natural Science Foundation of ChinaProject (EREH050303) supported by the Foundation of Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health
文摘The contamination and environmental risk assessment of the toxic elements in sediments from the middle-downstream (Zhuzhou-Changsha section) of the Xiangjiang River in Hunan Province of China were studied. The results show that As, Cd, Pb and Zn are major contaminants in sediments, and average concentrations of these elements significantly exceed both the Control Standards for Pollutants in Sludge of China (GB4284-84) for agricultural use in acidic soils and the effect range median (ERM) values. The average concentrations of As, Cd and Pb in the river water slightly exceed the limit of Surface Water Environment Quality Standard (GB3838-2002). The concentrations of As and Cr in depth profiles extensively change, but slight changes are observed in Pb and Zn. Cd and Zn in most sediment samples can easily enter the food-chain and bring possible ecotoxicological risk to organisms living in sediments according to the risk assessment code.
