City outskirts serve as the concentration centers for the pollutants discharged from various sources such as industry,agriculture and transportation.With the acceleration of industrialization and urbanization,the eco-...City outskirts serve as the concentration centers for the pollutants discharged from various sources such as industry,agriculture and transportation.With the acceleration of industrialization and urbanization,the eco-environment of the city outskirts has become a hot spot of public concern.An analysis was conducted in this paper on the soil in the outskirts of Yixing City using frequency distribution functions.The heavy metal sources in this region had been divided into two components,i.e.natural background component and strong human disturbance component.The corresponding interpretation of the distribution pattern and features of heavy metal elements was presented by spatial analysis.The results showed that the strong human disturbance components of Hg,Pb,and Cu accounted for 36.9%, 26.7%,and 23.3%in their contents respectively,which indicated directly the serious effect of human activities on heavy metal contents.Hg and Pb,because of the human disturbance,showed the greatest spatial variability,and human activities intensified the heterogeneity of the spatial distribution.The anisotropic analysis showed the higher organisation of Hg and Zn in the direction of urban-rural transition,which indicated their spatial characteristics with urban-rural transition.Pb displayed distinctive structure in the vertical direction of urban-rural transition,which was largely controlled by highway distribution.Cu content in paddy fields was significantly higher than those of other land-use-types,and the agricultural non-point source pollution played an important role in the distribution pattern of Cu.展开更多
【目的】探讨兰州市城郊林草地土壤碳通量变化规律,定量估算土壤碳排放量,为城市与城郊区碳排放和碳循环研究提供参考依据。【方法】以兰州市城郊“小青山水土保持科技示范园”内刺槐、苜蓿和沙打旺为试验样地,利用LI-8150“土壤碳通量...【目的】探讨兰州市城郊林草地土壤碳通量变化规律,定量估算土壤碳排放量,为城市与城郊区碳排放和碳循环研究提供参考依据。【方法】以兰州市城郊“小青山水土保持科技示范园”内刺槐、苜蓿和沙打旺为试验样地,利用LI-8150“土壤碳通量测量系统”对三种林草地土壤碳通量进行长期连续监测,分析土壤碳释放特征,阐明土壤碳通量与影响因素间的相关关系。【结果】①兰州市城郊三种林草地土壤碳通量最高值出现在每天下午14:00左右,最低值在凌晨6:00左右;早上10:00和晚上20:00左右的土壤碳通量值与日均值基本一致。苜蓿草地年度土壤碳排放量为2321.30 g m^(−2),高于刺槐林地1.24倍、沙打旺草地1.48倍。②三种林草地之间的地表温度变化和5 cm深处土壤温度变化规律一致,均无显著差异(P>0.05),地表温度和5 cm土壤温度都与土壤碳通量具有显著的正指数相关关系(P<0.05),其中刺槐林地土壤碳通量对温度的敏感性最高。③三种林草地土壤碳通量与太阳辐射强度显著相关(P<0.05),刺槐林地土壤碳通量与降雨量呈抛物线状显著相关(P<0.05)。【结论】兰州市城郊林草地在每天下午14:00左右土壤碳通量最高,苜蓿草地土壤二氧化碳排放量最高,温度和太阳辐射强度与土壤碳通量显著正相关(P<0.05)。展开更多
基金Supported by the Key Project of the National Natural Science Foundation of China(Grant No.90411015)the National Basic Research Program of China(Grant No.2002CB410810)
文摘City outskirts serve as the concentration centers for the pollutants discharged from various sources such as industry,agriculture and transportation.With the acceleration of industrialization and urbanization,the eco-environment of the city outskirts has become a hot spot of public concern.An analysis was conducted in this paper on the soil in the outskirts of Yixing City using frequency distribution functions.The heavy metal sources in this region had been divided into two components,i.e.natural background component and strong human disturbance component.The corresponding interpretation of the distribution pattern and features of heavy metal elements was presented by spatial analysis.The results showed that the strong human disturbance components of Hg,Pb,and Cu accounted for 36.9%, 26.7%,and 23.3%in their contents respectively,which indicated directly the serious effect of human activities on heavy metal contents.Hg and Pb,because of the human disturbance,showed the greatest spatial variability,and human activities intensified the heterogeneity of the spatial distribution.The anisotropic analysis showed the higher organisation of Hg and Zn in the direction of urban-rural transition,which indicated their spatial characteristics with urban-rural transition.Pb displayed distinctive structure in the vertical direction of urban-rural transition,which was largely controlled by highway distribution.Cu content in paddy fields was significantly higher than those of other land-use-types,and the agricultural non-point source pollution played an important role in the distribution pattern of Cu.
文摘【目的】探讨兰州市城郊林草地土壤碳通量变化规律,定量估算土壤碳排放量,为城市与城郊区碳排放和碳循环研究提供参考依据。【方法】以兰州市城郊“小青山水土保持科技示范园”内刺槐、苜蓿和沙打旺为试验样地,利用LI-8150“土壤碳通量测量系统”对三种林草地土壤碳通量进行长期连续监测,分析土壤碳释放特征,阐明土壤碳通量与影响因素间的相关关系。【结果】①兰州市城郊三种林草地土壤碳通量最高值出现在每天下午14:00左右,最低值在凌晨6:00左右;早上10:00和晚上20:00左右的土壤碳通量值与日均值基本一致。苜蓿草地年度土壤碳排放量为2321.30 g m^(−2),高于刺槐林地1.24倍、沙打旺草地1.48倍。②三种林草地之间的地表温度变化和5 cm深处土壤温度变化规律一致,均无显著差异(P>0.05),地表温度和5 cm土壤温度都与土壤碳通量具有显著的正指数相关关系(P<0.05),其中刺槐林地土壤碳通量对温度的敏感性最高。③三种林草地土壤碳通量与太阳辐射强度显著相关(P<0.05),刺槐林地土壤碳通量与降雨量呈抛物线状显著相关(P<0.05)。【结论】兰州市城郊林草地在每天下午14:00左右土壤碳通量最高,苜蓿草地土壤二氧化碳排放量最高,温度和太阳辐射强度与土壤碳通量显著正相关(P<0.05)。
