Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms af...Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers＇ livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.展开更多
The objective of this study was to determine the contamination of OCPs （organochlorine pesticides） in sediments from the upper middle of Sao Francisco River （Bahia, Brazil） in order to evaluate their potential pol...The objective of this study was to determine the contamination of OCPs （organochlorine pesticides） in sediments from the upper middle of Sao Francisco River （Bahia, Brazil） in order to evaluate their potential pollution risks. Samples of surface sediments were collected using a Petersen dredge at 21 stations located between Sobradinho and Cura^i. The organochlorine compounds analyzed were： p,p＇-DDT, p,p＇-DDD, p,p＇-DDE, dicofol, methoxychlor, HCHs, aldrin, endrin, endrin aldehyde, endrin ketone, dieldrin, heptachlor, heptachlor epoxide, endosulfan （ct, fl and sulfate） and chlordane （ct and ,/）. Extractions were carried out using the MAE （microwave-assisted extraction） method and organochlorine pesticides determination was achieved by GC/MS （gas chromatography-mass spectrometry）. Organochlorine concentrations ranged between 1.51-820.00 ng.gx, indicating very low to high levels. The most frequent OCPs were endrin aldehyde, -HCH, HCH, HCH, heptachlor and heptachlor epoxide.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 40601006, 40471009)National Basic Rsearch Program of China (No. 2005CB422006)
文摘Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers＇ livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.
文摘The objective of this study was to determine the contamination of OCPs （organochlorine pesticides） in sediments from the upper middle of Sao Francisco River （Bahia, Brazil） in order to evaluate their potential pollution risks. Samples of surface sediments were collected using a Petersen dredge at 21 stations located between Sobradinho and Cura^i. The organochlorine compounds analyzed were： p,p＇-DDT, p,p＇-DDD, p,p＇-DDE, dicofol, methoxychlor, HCHs, aldrin, endrin, endrin aldehyde, endrin ketone, dieldrin, heptachlor, heptachlor epoxide, endosulfan （ct, fl and sulfate） and chlordane （ct and ,/）. Extractions were carried out using the MAE （microwave-assisted extraction） method and organochlorine pesticides determination was achieved by GC/MS （gas chromatography-mass spectrometry）. Organochlorine concentrations ranged between 1.51-820.00 ng.gx, indicating very low to high levels. The most frequent OCPs were endrin aldehyde, -HCH, HCH, HCH, heptachlor and heptachlor epoxide.
