Land use reflects human activities on land.Urban land use is the highest level human alteration on Earth,and it is rapidly changing due to population increase and urbanization.Urban areas have widespread effects on lo...Land use reflects human activities on land.Urban land use is the highest level human alteration on Earth,and it is rapidly changing due to population increase and urbanization.Urban areas have widespread effects on local hydrology,climate,biodiversity,and food production[1,2].However,maps,that contain knowledge on the distribution,pattern and composition of various land use types in urban areas,are limited to city level.The mapping standard on data sources,methods,land use classification schemes varies from city to city,due to differences in financial input and skills of mapping personnel.To address various national and global environmental challenges caused by urbanization,it is important to have urban land uses at the national and global scales that are derived from the same or consistent data sources with the same or compatible classification systems and mapping methods.This is because,only with urban land use maps produced with similar criteria,consistent environmental policies can be made,and action efforts can be compared and assessed for large scale environmental administration.However,despite of the fact that a number of urban-extent maps exist at global scales[3,4],more detailed urban land use maps do not exist at the same scale.Even at big country or regional levels such as for the United States,China and European Union,consistent land use mapping efforts are rare[5,6](e.g.,https://sdi4apps.eu/open_land_use/).展开更多
为了解凌云白毫绿茶的主要香气成分,同时探明不同季节凌云白毫绿茶的香气成分差异。通过动态顶空-气相色谱-质谱技术对春、夏、秋3季凌云白毫绿茶的香气成分进行定性定量测定,基于茶样中各香气成分的相对含量,通过偏最小二乘-判别分析(p...为了解凌云白毫绿茶的主要香气成分,同时探明不同季节凌云白毫绿茶的香气成分差异。通过动态顶空-气相色谱-质谱技术对春、夏、秋3季凌云白毫绿茶的香气成分进行定性定量测定,基于茶样中各香气成分的相对含量,通过偏最小二乘-判别分析(partial least square-discriminant analysis,PLS-DA)建立不同季节茶叶判别模型,然后找到对分类起关键作用的香气成分,最后通过绘制热图和层次聚类分析确定各关键香气成分在不同季节凌云白毫绿茶中的分布规律。结果表明,本研究共鉴定出37种化合物,其中醇类和醛类化合物数量较多;凌云白毫绿茶主要香气成分为芳樟醇、正戊醇、香叶醇、L-薄荷醇、异丁醛、异戊醛、壬醛、乙酸乙酯、二甲硫醚、吲哚。建立的PLS-DA模型可以将3个季节的茶样明显区分,且模型可靠;本研究最终鉴定出12种香气成分区分不同季节凌云白毫绿茶的关键化合物,分别为壬醛、β-紫罗兰酮、L-薄荷醇、3,5-辛二烯-2-酮、反-橙花叔醇、苯甲醇、正戊醇、十三烷、顺式-2-戊烯-1-醇、顺-茉莉酮、十四烷、叶醇。结合热图及12种香气成分的聚类分析,表明L-薄荷醇和β-紫罗兰酮在秋茶中相对含量最高,是凌云白毫秋茶区别于春茶和夏茶的特征香气成分,主要表现为花香、果香、薄荷味;苯甲醇和正戊醇在春茶中相对含量较高,是凌云白毫春茶区别于夏茶和秋茶的特征香气成分,主要表现为果香、杏仁苦味;壬醛、3,5-辛二烯-2-酮、反-橙花叔醇在夏茶中相对含量最高,是夏茶的特征香气成分,香气主要为柑橘柠檬香、水果甜香。展开更多
基金partially supported by the National Key Research and Development Program of China(2016YFA0600104)supported by donations made by Delos Living LLC,and the Cyrus Tang Foundation+2 种基金supported by the National Natural Science Foundation of China(41471419)Beijing Institute of Urban Planningsupported by the Fundamental Research Funds for the Central Universities(CCNU19TD002).
文摘Land use reflects human activities on land.Urban land use is the highest level human alteration on Earth,and it is rapidly changing due to population increase and urbanization.Urban areas have widespread effects on local hydrology,climate,biodiversity,and food production[1,2].However,maps,that contain knowledge on the distribution,pattern and composition of various land use types in urban areas,are limited to city level.The mapping standard on data sources,methods,land use classification schemes varies from city to city,due to differences in financial input and skills of mapping personnel.To address various national and global environmental challenges caused by urbanization,it is important to have urban land uses at the national and global scales that are derived from the same or consistent data sources with the same or compatible classification systems and mapping methods.This is because,only with urban land use maps produced with similar criteria,consistent environmental policies can be made,and action efforts can be compared and assessed for large scale environmental administration.However,despite of the fact that a number of urban-extent maps exist at global scales[3,4],more detailed urban land use maps do not exist at the same scale.Even at big country or regional levels such as for the United States,China and European Union,consistent land use mapping efforts are rare[5,6](e.g.,https://sdi4apps.eu/open_land_use/).
文摘为了解凌云白毫绿茶的主要香气成分,同时探明不同季节凌云白毫绿茶的香气成分差异。通过动态顶空-气相色谱-质谱技术对春、夏、秋3季凌云白毫绿茶的香气成分进行定性定量测定,基于茶样中各香气成分的相对含量,通过偏最小二乘-判别分析(partial least square-discriminant analysis,PLS-DA)建立不同季节茶叶判别模型,然后找到对分类起关键作用的香气成分,最后通过绘制热图和层次聚类分析确定各关键香气成分在不同季节凌云白毫绿茶中的分布规律。结果表明,本研究共鉴定出37种化合物,其中醇类和醛类化合物数量较多;凌云白毫绿茶主要香气成分为芳樟醇、正戊醇、香叶醇、L-薄荷醇、异丁醛、异戊醛、壬醛、乙酸乙酯、二甲硫醚、吲哚。建立的PLS-DA模型可以将3个季节的茶样明显区分,且模型可靠;本研究最终鉴定出12种香气成分区分不同季节凌云白毫绿茶的关键化合物,分别为壬醛、β-紫罗兰酮、L-薄荷醇、3,5-辛二烯-2-酮、反-橙花叔醇、苯甲醇、正戊醇、十三烷、顺式-2-戊烯-1-醇、顺-茉莉酮、十四烷、叶醇。结合热图及12种香气成分的聚类分析,表明L-薄荷醇和β-紫罗兰酮在秋茶中相对含量最高,是凌云白毫秋茶区别于春茶和夏茶的特征香气成分,主要表现为花香、果香、薄荷味;苯甲醇和正戊醇在春茶中相对含量较高,是凌云白毫春茶区别于夏茶和秋茶的特征香气成分,主要表现为果香、杏仁苦味;壬醛、3,5-辛二烯-2-酮、反-橙花叔醇在夏茶中相对含量最高,是夏茶的特征香气成分,香气主要为柑橘柠檬香、水果甜香。
