Urban soil, forming along with the development of city, has unique properties of soil organic carbon. On the basis of field investigation and laboratory analysis, soil organic carbon (SOC) of Kaifeng city was studied, and the results showed that the characteristics of SOC were different not only among function districts in urban area, but also between urban area and suburbs. The order of SOC in topsoil was industrial district > recreational district > traffic district > cultural/educational district > residential/administrative district. The density of soil organic carbon (SOCD) in both topsoil and profile followed the orders of recreational district >industrial district > traffic district>cultural/educational district > residential/adminis- trative district, and cultural/educational district > traffic district>industrial district>recreational district > administrative/residential district, respectively. SOCD in both topsoil and profile decreased along the transection line from urban area to suburbs and urban area had 2.53-fold more SOCD in topsoil and 1.56-fold more SOCD in profile than suburbs, respectively. SOC decreased with the depth and was mainly distributed within the scope of 0-30 cm. The variances of SOC in urban area were more complicated than that in suburbs. 相似文献
基于区域创新集群的相关概念辨析,提出基于长三角一体化战略的区域创新集群概念,并通过IncoPat网站获取2000—2017年长三角新材料产业已获授权的发明专利,在刻画新材料区域创新集群技术创新联系特征的基础上,利用二步系统广义矩阵估计(Generalized Method of Moments,GMM)模型测度融入区域创新集群的深度与广度对地方创新集群的影响,得到如下结论:第一,区域创新集群的发展符合“点-轴”发展理论的观点,以上海、南京、杭州等发达地方创新集群为增长极,在空间上率先形成以增长极为节点的发展轴,成为区域创新集群的核心组团。第二,区域创新集群技术创新联系具备“全球-地方”创新网络阐述的多种类型知识交互耦合的特征,在同质性知识交互的基础上,异质性知识的交互同样占据重要地位。第三,当前阶段长三角区域创新集群中核心组团的极化效应大于扩散效应,更易在区域创新集群的建设中获益,并且知识基础的正向调节作用明显。区域创新集群研究尚处于起步阶段,相关研究亟待经济地理学者进一步展开。 相似文献
气象观测资料表明,在当前全球暖化背景下高海拔地区的增温速率更快,其气候对全球气候变化的响应更为敏感。但是,高海拔地区如何响应快速气候事件,由于古气候古环境重建资料在高海拔地区较少,这一问题还没有很好的回答。为此选择云南省高山湖泊错恰湖为研究对象(海拔约3960 m),分析了湖泊沉积岩芯(深度范围90~244 cm)中正构烷烃的分布特征,重建了末次冰消期(19000~9500 a B.P.)沉积物有机质来源的变化,进而推断古气候演变。在17800~17000 a B.P.,错恰湖有机质以陆源输入为主,水生贡献相对减少,气候以暖湿为主;在17000~15100 a B.P.,水生有机质的贡献的比例增加,气候以冷干为主;在15100~12700 a B.P.,湖泊沉积有机质的陆源贡献增加,水生贡献相对减少,气候相对暖湿;在12700~11400 a B.P.时段,湖泊沉积水生有机质来源相对增多,气候相对冷干。与其他区域和全球气候记录对比发现,错恰湖的沉积记录指示的气候变化事件,受高纬冰量以及北大西洋驱动的西南季风突变所影响,在末次冰消期记录的4个明显的千年尺度气候事件,在时间上与First warmth、H1、B-A和YD事件相对应。与云南地区其他湖泊记录对比发现,小型湖泊或高海拔湖泊对这些全球快速气候事件的响应更加敏感。