This paper presents a summary of the characteristics of China's rural labor force based on data from the 1996 and 2006 agriculture censuses.In this paper,we re-estimate,compare and analyze China's rural labor ...This paper presents a summary of the characteristics of China's rural labor force based on data from the 1996 and 2006 agriculture censuses.In this paper,we re-estimate,compare and analyze China's rural labor surplus at national and provincial levels using the labor-hour conversion method and the standard structural approach.Taking economic cycle fluctuations into account,we also investigate the root causes for the co-existence of a migrant worker shortage and an agricultural labor surplus.Our study indicates that we can make realistic judgments about rural labor supply and demand only by removing short-term disturbing factors associated with economic boom and bust cycles.展开更多
Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This stu...Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This study proposes a structural equation model to assist in the establishment of a lake nutrient standard for drinking water sources in Yunnan-Guizhou Plateau Ecoregion （Yungui Ecoregion）, China. The modeling results indicate that the most predictive indicator for designated use-attainment is total phosphorus （TP） （total effect =-0.43）, and chlorophyll a （Chl-a） is recommended as the second important indicator （total effect =-0.41）. The model is further used for estimating the probability of use-attainment associated with lake water as a drinking water source and various levels of candidate criteria （based on the reference conditions and the current environmental quality standards for surface water）. It is found that these candidate criteria cannot satisfy the designated 100% use-attainment. To achieve the short-term target （85% attainment of the designated use）, TP and Chl-a values ought to be less than 0.02 mg/L and 1.4 μg/L, respectively. When used as a long-term target （90% or greater attainment of the designated use）, the TP and Chl-a values are suggested to be less than 0.018 mg/L and 1 μg/L, respectively.展开更多
文摘This paper presents a summary of the characteristics of China's rural labor force based on data from the 1996 and 2006 agriculture censuses.In this paper,we re-estimate,compare and analyze China's rural labor surplus at national and provincial levels using the labor-hour conversion method and the standard structural approach.Taking economic cycle fluctuations into account,we also investigate the root causes for the co-existence of a migrant worker shortage and an agricultural labor surplus.Our study indicates that we can make realistic judgments about rural labor supply and demand only by removing short-term disturbing factors associated with economic boom and bust cycles.
基金supported by the Mega-projects of Science Research for Water Environment Improvement (No. 2009ZX07106-001-005-01)the National Nature Science Foundation of China (No. 71103166)
文摘Lake eutrophication （LE） has become an increasingly severe environmental problem recently. However, there has been no nutrient standard established for LE control in many developing countries such as China. This study proposes a structural equation model to assist in the establishment of a lake nutrient standard for drinking water sources in Yunnan-Guizhou Plateau Ecoregion （Yungui Ecoregion）, China. The modeling results indicate that the most predictive indicator for designated use-attainment is total phosphorus （TP） （total effect =-0.43）, and chlorophyll a （Chl-a） is recommended as the second important indicator （total effect =-0.41）. The model is further used for estimating the probability of use-attainment associated with lake water as a drinking water source and various levels of candidate criteria （based on the reference conditions and the current environmental quality standards for surface water）. It is found that these candidate criteria cannot satisfy the designated 100% use-attainment. To achieve the short-term target （85% attainment of the designated use）, TP and Chl-a values ought to be less than 0.02 mg/L and 1.4 μg/L, respectively. When used as a long-term target （90% or greater attainment of the designated use）, the TP and Chl-a values are suggested to be less than 0.018 mg/L and 1 μg/L, respectively.
