A An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of 24 elements （Be, Mg, A1, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, ...A An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of 24 elements （Be, Mg, A1, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn Sb, Ba, Pt, Au, and Pb） in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCI. The matrix effects because of the presence of excess HCI and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 ].tg·g^-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.展开更多
In recent years,the phenomenon of abandonment of cultivated land in mountainous areas has occurred frequently,and the problem of abandonment has become a focus of attention of government agricultural departments and a...In recent years,the phenomenon of abandonment of cultivated land in mountainous areas has occurred frequently,and the problem of abandonment has become a focus of attention of government agricultural departments and academic circles.However,few studies have paid attention to the impact of differences in labor transfer on the abandonment behavior of farmers’terraced fields.Based on this,this paper takes the terraced fields of Hunan,Fujian and Jiangxi provinces as the research area,combined with data from 1438 farmer households,and uses the Probit and Tobit models to analyzed the impact of the difference in the quantity,distance and quality of labor off-farm transfer on the decision-making and scale of terraced field abandonment of farmer households.The results show that:(1)The greater the quantity of labor transfer,the farther the transfer distance and the higher the quality of non-agricultural employment,can promote the decision of farmers to abandon terraced fields;(2)With the deepening of the degree of non-agricultural transfer,the scale of abandoned terraced fields by farmers in hilly and mountainous areas will also expand;(3)The distance and quality of labor transfer can strengthen the impact of labor transfer quantity on farmers’decision to abandon land.To alleviate the phenomenon of abandoned terraced fields,the government should pay attention to the labor substitution role of agricultural service outsourcing and mechanization in mountainous areas.The government should actively promote the transformation of terraced fields into mechanized farming,improve the cultivated land transfer market,and encourage farmers to transfer terraced fields.展开更多
Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality slop...Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces.The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects.A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China,and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China.The main findings are as follows:(1)The phenomenon of terrace abandonment was widespread throughout the country,with 54% of the total surveyed villages exhibiting terrace abandonment,and the area of abandoned terraces accounting for 9.79% of the total.(2) The degree of terrace abandonment is high in the south and low in the north.The most serious region with abandonment was the hilly and mountainous areas in the south,especially in the middle and lower Yangtze River region.(3)The main driving factors of terrace abandonment were rural labor migration,agricultural mechanization level,irrigation conditions,and transportation conditions for cultivation.Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment.Measures such as improving terrace mechanization are universally applicable.Specifically,low-quality terraces can be withdrawn orderly,and for high-quality terraces,multiple measures are needed to consolidate agricultural production,such as adjusting the planting structure,strengthening agricultural infrastructure construction,and encouraging the transfer of land-use rights as well as large-scale operation.展开更多
Cropland abandonment is common and widely distributed in hilly and mountainous areas.Clarifying the current situation and development of cropland abandonment can provide reference for the rational and classified manag...Cropland abandonment is common and widely distributed in hilly and mountainous areas.Clarifying the current situation and development of cropland abandonment can provide reference for the rational and classified management of cropland abandonment in hilly and mountainous areas.Taking Jiangxi Province as the study area,and using the Google Earth Engine and Landsat data,the scale and years of abandoned cropland from 2002 to 2020 were calculated by using the random forest classifier and rules for identifying cropland abandonment.The spatio-temporal pattern of cropland abandonment at the county level was analyzed.The results indicated that the overall accuracy of land use classification was over 90%.The cropland abandonment rate ranged from 3%to 5.5%from 2002 to 2020,while the cropland abandonment rate was highest in 2013 and showed a downward trend after 2017.Among the years,the area of first-time abandoned cropland was the largest in 2005.The distribution of the cropland abandonment rate was low in the middle and north,but high in the surrounding area and the south.A notable positive spatial correlation was observed in the cropland abandonment rate,with a gradual intensification of spatial clustering.The LISA cluster map revealed a significant north-south disparity,exhibiting an incremental trend over time in the characteristics of the“High-High”cluster in the Southeastern Mountainous Area and the“Low-Low”cluster in the Poyang Lake Hilly Plain in Jiangxi.The results of this study can provide data for extracting spatial information and analyzing the driving factors of cropland abandonment in hilly and mountainous areas,and they can also provide a basis for the development of policies for the utilization and classification management of abandoned cropland.展开更多
基金the Natural Science Foundation of Hunan Province, China (No. 05JJ40017).
文摘A An analytical method using high resolution inductively coupled plasma mass spectrometry （HR-ICP-MS） for rapid simultaneous determination of 24 elements （Be, Mg, A1, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn Sb, Ba, Pt, Au, and Pb） in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCI. The matrix effects because of the presence of excess HCI and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 ].tg·g^-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.
基金The National Natural Science Foundation of China(41971243,41961035)The Key Project of Jiangxi Natural Science Foundation(20202ACB203004)+1 种基金The 68th Batch of China Postdoctoral Science Foundation Funding(2020M682106)The 14th Batch of Jiangxi Postdoctoral Science Foundation Special Funding(2020KY29)。
基金National Natural Science Foundation of China,No.41930757,No.41971243。
文摘In recent years,the phenomenon of abandonment of cultivated land in mountainous areas has occurred frequently,and the problem of abandonment has become a focus of attention of government agricultural departments and academic circles.However,few studies have paid attention to the impact of differences in labor transfer on the abandonment behavior of farmers’terraced fields.Based on this,this paper takes the terraced fields of Hunan,Fujian and Jiangxi provinces as the research area,combined with data from 1438 farmer households,and uses the Probit and Tobit models to analyzed the impact of the difference in the quantity,distance and quality of labor off-farm transfer on the decision-making and scale of terraced field abandonment of farmer households.The results show that:(1)The greater the quantity of labor transfer,the farther the transfer distance and the higher the quality of non-agricultural employment,can promote the decision of farmers to abandon terraced fields;(2)With the deepening of the degree of non-agricultural transfer,the scale of abandoned terraced fields by farmers in hilly and mountainous areas will also expand;(3)The distance and quality of labor transfer can strengthen the impact of labor transfer quantity on farmers’decision to abandon land.To alleviate the phenomenon of abandoned terraced fields,the government should pay attention to the labor substitution role of agricultural service outsourcing and mechanization in mountainous areas.The government should actively promote the transformation of terraced fields into mechanized farming,improve the cultivated land transfer market,and encourage farmers to transfer terraced fields.
基金Key Program of National Natural Science Foundation of China,No.41930757GDAS’ Project of Science and Technology Development,No.2020GDASYL-20200104005。
文摘Driven by urbanization and industrialization,arable land in hilly and mountainous regions of China is gradually becoming marginalized,with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces.The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects.A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China,and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China.The main findings are as follows:(1)The phenomenon of terrace abandonment was widespread throughout the country,with 54% of the total surveyed villages exhibiting terrace abandonment,and the area of abandoned terraces accounting for 9.79% of the total.(2) The degree of terrace abandonment is high in the south and low in the north.The most serious region with abandonment was the hilly and mountainous areas in the south,especially in the middle and lower Yangtze River region.(3)The main driving factors of terrace abandonment were rural labor migration,agricultural mechanization level,irrigation conditions,and transportation conditions for cultivation.Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment.Measures such as improving terrace mechanization are universally applicable.Specifically,low-quality terraces can be withdrawn orderly,and for high-quality terraces,multiple measures are needed to consolidate agricultural production,such as adjusting the planting structure,strengthening agricultural infrastructure construction,and encouraging the transfer of land-use rights as well as large-scale operation.
基金The National Natural Science Foundation of China(42371285)。
文摘Cropland abandonment is common and widely distributed in hilly and mountainous areas.Clarifying the current situation and development of cropland abandonment can provide reference for the rational and classified management of cropland abandonment in hilly and mountainous areas.Taking Jiangxi Province as the study area,and using the Google Earth Engine and Landsat data,the scale and years of abandoned cropland from 2002 to 2020 were calculated by using the random forest classifier and rules for identifying cropland abandonment.The spatio-temporal pattern of cropland abandonment at the county level was analyzed.The results indicated that the overall accuracy of land use classification was over 90%.The cropland abandonment rate ranged from 3%to 5.5%from 2002 to 2020,while the cropland abandonment rate was highest in 2013 and showed a downward trend after 2017.Among the years,the area of first-time abandoned cropland was the largest in 2005.The distribution of the cropland abandonment rate was low in the middle and north,but high in the surrounding area and the south.A notable positive spatial correlation was observed in the cropland abandonment rate,with a gradual intensification of spatial clustering.The LISA cluster map revealed a significant north-south disparity,exhibiting an incremental trend over time in the characteristics of the“High-High”cluster in the Southeastern Mountainous Area and the“Low-Low”cluster in the Poyang Lake Hilly Plain in Jiangxi.The results of this study can provide data for extracting spatial information and analyzing the driving factors of cropland abandonment in hilly and mountainous areas,and they can also provide a basis for the development of policies for the utilization and classification management of abandoned cropland.
