To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region （Ningxia）, China, we sampled surface soil and measured the concentrations of 8 toxic ...To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region （Ningxia）, China, we sampled surface soil and measured the concentrations of 8 toxic metals （Pb, Cr, Cu, Zn, Co, Bi, Ni and V） using X-ray fluorescence spectrometry. The enrichment characteristics and sources of these toxic metals in the soil were analyzed by the enrichment factor （EF） and multivariate statistical analysis. The results showed that the mean concentrations of these toxic metals in the soil samples were 25.0, 109.1, 16.8, 26.0, 37.2, 2.7, 25.3 and 59.9 mg/kg for Pb, Cr, Cu, Zn, Co, Bi, Ni and V, respectively, which were 1.2, 1.8, 0.8, 0.4, 3.2, 8.7, 0.7 and 0.8 times of the corresponding background values of Ningxia soil, respectively. The variations of Pb, Zn, Co, Bi and Ni concentrations in the surface soil of Yinchuan were larger than those of the other metals. Our results also showed that the toxic metals investigated in the soil had different enrichment levels. Both Co and Bi were significantly enriched, whereas Cr was only moderately enriched in the soil. There was a deficiency or minimal enrichment of the other toxic metals in the soil. Source analysis results based on the concentration, enrichment characteristics and multivariate statistical analysis indicated that Cr, V and Ni originated from a combination of fossil fuel combustion, traffic pollution and natural occurrence. Pb, Cu and Zn were predominantly derived from natural and traffic sources, while Co and Bi primarily originated from construction sources.展开更多
Severe resource shortage and waste of resource in agricultural production make it necessary to assess efficiency to increase productivity with high efficiency and ensure sustainable agricultural development. This pape...Severe resource shortage and waste of resource in agricultural production make it necessary to assess efficiency to increase productivity with high efficiency and ensure sustainable agricultural development. This paper adopted an input-oriented data envelopment analysis(DEA) method with the assumption of variable returns to scale to evaluate agricultural production efficiency of 100 major irrigation districts in Northwest China in 2010.Major findings of this paper were as follows: firstly, the average value of total technical efficiency, pure technical efficiency and scale efficiency of those irrigation districts in Northwest China were 0.770, 0.825 and 0.931,respectively; secondly, 30% of irrigation districts were technically efficient, while 42% and 32% of them showed pure technical and scale efficiency respectively. Among inefficient decision-making units, total technical efficiency score varied from 0.313 to 0.966, showing significant geographical differences, but geographical differences of pure technical efficiency was more consistent with that of total technical efficiency; thirdly, input redundancy was evident. Inputs of agricultural population, irrigation area,green water, blue water, consumption of fertilizer and agricultural machinery could be reduced by 34.88%,40.19%, 43.85%, 47.10%, 41.53% and 42.21% respectively without reducing agricultural outputs. Furthermore,irrigation area, green water and blue water had relatively high slack movement though Northwest China which is short of water resources. Based on these results, this paper drew the following conclusions: First, there is huge potential for Northwest China to improve its agricultural production efficiency, and agro-technology not input scale had greater influence on improvement. Second, farmers needed proper guidance in order to reduce agricultural inputs and it is time to centralize agricultural management for overall agricultural inputs regulation and control.展开更多
潜在植被是指在没有人为干扰、在现有的环境条件下,植被的全部演替系列完成时立地应该存在的植被状况。西北干旱区生态环境问题突出,以潜在植被为研究对象来探究西北干旱区植被背景及其变化规律,成为西部生态环境恢复重建的基础性工作...潜在植被是指在没有人为干扰、在现有的环境条件下,植被的全部演替系列完成时立地应该存在的植被状况。西北干旱区生态环境问题突出,以潜在植被为研究对象来探究西北干旱区植被背景及其变化规律,成为西部生态环境恢复重建的基础性工作。本研究以IOCSG(integrated orderly classification system of grassland)模型为潜在植被评定模型,在GIS研究方法的支持下,对西北干旱区潜在植被进行了模拟,并对其动态变化进行了分析,得出以下结论:1)采用IOCSG评定模型对中国西北干旱区潜在植被分布进行了模拟,通过检验得出,IOCSG评定模型对研究区植被模拟精度达到了78%,较好的重现了研究区潜在植被分布格局。2)分布在研究区的潜在植被类型有21类,不同区域植被的多样性差异较大。天山、阿尔泰山一带及大兴安岭地区植被分布较为丰富。相比之下,准噶尔盆地、塔里木盆地、巴丹吉林沙漠地区分布比较单一,主要以荒漠、半荒漠为主。3)由于立地气候环境的改变,区域植被系统表现出不稳定性,主要表现为4个特点:扩展变化、缩减变化、波动性变化以及消亡变化。4)气候环境适应性的改变使潜在植被发生了演替过程,从2个周期的变化来看,天山、阿尔泰山、大兴安岭及以西地区以及呼伦贝尔高原地区成为植被演替的敏感区。展开更多
基金supported by the National Natural Science Foundation of China (41271510, 41461098)the Fundamental Research Funds for the Central Universities of China (GK201601009, 2017TS027)
文摘To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region （Ningxia）, China, we sampled surface soil and measured the concentrations of 8 toxic metals （Pb, Cr, Cu, Zn, Co, Bi, Ni and V） using X-ray fluorescence spectrometry. The enrichment characteristics and sources of these toxic metals in the soil were analyzed by the enrichment factor （EF） and multivariate statistical analysis. The results showed that the mean concentrations of these toxic metals in the soil samples were 25.0, 109.1, 16.8, 26.0, 37.2, 2.7, 25.3 and 59.9 mg/kg for Pb, Cr, Cu, Zn, Co, Bi, Ni and V, respectively, which were 1.2, 1.8, 0.8, 0.4, 3.2, 8.7, 0.7 and 0.8 times of the corresponding background values of Ningxia soil, respectively. The variations of Pb, Zn, Co, Bi and Ni concentrations in the surface soil of Yinchuan were larger than those of the other metals. Our results also showed that the toxic metals investigated in the soil had different enrichment levels. Both Co and Bi were significantly enriched, whereas Cr was only moderately enriched in the soil. There was a deficiency or minimal enrichment of the other toxic metals in the soil. Source analysis results based on the concentration, enrichment characteristics and multivariate statistical analysis indicated that Cr, V and Ni originated from a combination of fossil fuel combustion, traffic pollution and natural occurrence. Pb, Cu and Zn were predominantly derived from natural and traffic sources, while Co and Bi primarily originated from construction sources.
基金supported by the National Key Research and Development Program (2016YFC0400201, 2016YFC0400 205)the ‘111’ Project from the Ministry of Education of China and the State Administration of Foreign Experts Affairs of China (B12007)the Science and Technology Planning Project of Yangling Demonstration Zone (2015NY-16)
文摘Severe resource shortage and waste of resource in agricultural production make it necessary to assess efficiency to increase productivity with high efficiency and ensure sustainable agricultural development. This paper adopted an input-oriented data envelopment analysis(DEA) method with the assumption of variable returns to scale to evaluate agricultural production efficiency of 100 major irrigation districts in Northwest China in 2010.Major findings of this paper were as follows: firstly, the average value of total technical efficiency, pure technical efficiency and scale efficiency of those irrigation districts in Northwest China were 0.770, 0.825 and 0.931,respectively; secondly, 30% of irrigation districts were technically efficient, while 42% and 32% of them showed pure technical and scale efficiency respectively. Among inefficient decision-making units, total technical efficiency score varied from 0.313 to 0.966, showing significant geographical differences, but geographical differences of pure technical efficiency was more consistent with that of total technical efficiency; thirdly, input redundancy was evident. Inputs of agricultural population, irrigation area,green water, blue water, consumption of fertilizer and agricultural machinery could be reduced by 34.88%,40.19%, 43.85%, 47.10%, 41.53% and 42.21% respectively without reducing agricultural outputs. Furthermore,irrigation area, green water and blue water had relatively high slack movement though Northwest China which is short of water resources. Based on these results, this paper drew the following conclusions: First, there is huge potential for Northwest China to improve its agricultural production efficiency, and agro-technology not input scale had greater influence on improvement. Second, farmers needed proper guidance in order to reduce agricultural inputs and it is time to centralize agricultural management for overall agricultural inputs regulation and control.
文摘潜在植被是指在没有人为干扰、在现有的环境条件下,植被的全部演替系列完成时立地应该存在的植被状况。西北干旱区生态环境问题突出,以潜在植被为研究对象来探究西北干旱区植被背景及其变化规律,成为西部生态环境恢复重建的基础性工作。本研究以IOCSG(integrated orderly classification system of grassland)模型为潜在植被评定模型,在GIS研究方法的支持下,对西北干旱区潜在植被进行了模拟,并对其动态变化进行了分析,得出以下结论:1)采用IOCSG评定模型对中国西北干旱区潜在植被分布进行了模拟,通过检验得出,IOCSG评定模型对研究区植被模拟精度达到了78%,较好的重现了研究区潜在植被分布格局。2)分布在研究区的潜在植被类型有21类,不同区域植被的多样性差异较大。天山、阿尔泰山一带及大兴安岭地区植被分布较为丰富。相比之下,准噶尔盆地、塔里木盆地、巴丹吉林沙漠地区分布比较单一,主要以荒漠、半荒漠为主。3)由于立地气候环境的改变,区域植被系统表现出不稳定性,主要表现为4个特点:扩展变化、缩减变化、波动性变化以及消亡变化。4)气候环境适应性的改变使潜在植被发生了演替过程,从2个周期的变化来看,天山、阿尔泰山、大兴安岭及以西地区以及呼伦贝尔高原地区成为植被演替的敏感区。
