According to the historical changes of coastal lines, seven soil sampling districts, from land to sea, were arranged in Dongtai City, Jiangsu Province to sample soils from surface and profile. Concentrations of seven ...According to the historical changes of coastal lines, seven soil sampling districts, from land to sea, were arranged in Dongtai City, Jiangsu Province to sample soils from surface and profile. Concentrations of seven major heavy metals (HMs), granularity, pH, organic matters and C/N of the soil samples were analyzed. Results show that concentrations of heavy metals in agricultural land present a certain spatial variance, decreasing from land to sea. Pollution assessment indicates that the agricultural soils were not polluted by HMs, but the potential pollution of Cu and Hg needs to be alerted. Different HMs accumulate in the surface and sub-surface of the soil profiles, and concentrations of Hg and Pb decrease significantly with the increment of soil depth. Concentrations of HMs exhibit a significantly negative correlation to pH, but have no significant relation with organic matters in soil. Principle component analysis show that the concentrations of HMs relate to the land use history. Concentrations of Hg, Ni and Cr in soil are closely related with land use history, and concentrations of Pb, Cu and Cr are affected by land use history as well as other factors. However, there is no significant relation between concentration of As and land use history.展开更多
To understand historical human-induced land use/cover change （LUCC） and its climatic effects, it is essential to reconstruct historical land use/cover changes with explicit spatial information. In this study, based ...To understand historical human-induced land use/cover change （LUCC） and its climatic effects, it is essential to reconstruct historical land use/cover changes with explicit spatial information. In this study, based on the historically documented cropland area at county level, we reconstructed the spatially explicit cropland distribution at a cell size of 1 km × 1 km for the Songnen Plain in the late Qing Dynasty （1908 AD）. The reconstructions were carried out using two methods. One method （hereafter, referred to as method 1） allocated the cropland to cells ordered from a high agricultural suitability index （ASI） to a low ASI, but they were all within the domain of potential cropland area. The potential cropland area was created by excluding natural woodland, swamp, water bodies, and mountains from the study area. The other method （hereafter, method II） allocated the cropland to cells in the order from high ASI to low ASI within the domain of cropland area in 1959. This method was based on the hypothesis that the cropland area domain in 1959 resulted from enlargement of the cropland area domain in 1908. We then compared these two reconstructions. We found that the crop- land distributions reconstructed by the two methods exhibit a similar spatial distribution pat- tern. Both reconstructions show that the cropland was mostly found in the southern and eastern parts of the Songnen Plain. The two reconstructions matched each other for about 68% of the total cropland area. By spatially comparing the unmatched cropland cells of the two reconstructions with the settlements for each county, we found that unmatched cropland cells from method I are closer to settlements than those from method I1. This finding suggests that reconstruction using method I may have less bias than reconstruction with method I1.展开更多
China Mobile Profits Soar on Record Subscriber Growth;Beijing Airport Axes Hundreds of Flights;Citigroup Extends Private Banking Reach in China;Shenzhen Development Bank in RMB 7bn Bond Sale;Google Ramps up China Pres...China Mobile Profits Soar on Record Subscriber Growth;Beijing Airport Axes Hundreds of Flights;Citigroup Extends Private Banking Reach in China;Shenzhen Development Bank in RMB 7bn Bond Sale;Google Ramps up China Presence with Tianya Stake;展开更多
基金Under the auspices of State Key Development Program for Basic Research of China (No 2002CB410810)
文摘According to the historical changes of coastal lines, seven soil sampling districts, from land to sea, were arranged in Dongtai City, Jiangsu Province to sample soils from surface and profile. Concentrations of seven major heavy metals (HMs), granularity, pH, organic matters and C/N of the soil samples were analyzed. Results show that concentrations of heavy metals in agricultural land present a certain spatial variance, decreasing from land to sea. Pollution assessment indicates that the agricultural soils were not polluted by HMs, but the potential pollution of Cu and Hg needs to be alerted. Different HMs accumulate in the surface and sub-surface of the soil profiles, and concentrations of Hg and Pb decrease significantly with the increment of soil depth. Concentrations of HMs exhibit a significantly negative correlation to pH, but have no significant relation with organic matters in soil. Principle component analysis show that the concentrations of HMs relate to the land use history. Concentrations of Hg, Ni and Cr in soil are closely related with land use history, and concentrations of Pb, Cu and Cr are affected by land use history as well as other factors. However, there is no significant relation between concentration of As and land use history.
基金National Natural Science Foundation of ChinaNo.42171217,No.41471171+1 种基金Doctorial Innovation Fund,No.HSDBSCX 2015-12Natural Science of Foundation of Heilongjiang Province,No.ZD201308
文摘To understand historical human-induced land use/cover change （LUCC） and its climatic effects, it is essential to reconstruct historical land use/cover changes with explicit spatial information. In this study, based on the historically documented cropland area at county level, we reconstructed the spatially explicit cropland distribution at a cell size of 1 km × 1 km for the Songnen Plain in the late Qing Dynasty （1908 AD）. The reconstructions were carried out using two methods. One method （hereafter, referred to as method 1） allocated the cropland to cells ordered from a high agricultural suitability index （ASI） to a low ASI, but they were all within the domain of potential cropland area. The potential cropland area was created by excluding natural woodland, swamp, water bodies, and mountains from the study area. The other method （hereafter, method II） allocated the cropland to cells in the order from high ASI to low ASI within the domain of cropland area in 1959. This method was based on the hypothesis that the cropland area domain in 1959 resulted from enlargement of the cropland area domain in 1908. We then compared these two reconstructions. We found that the crop- land distributions reconstructed by the two methods exhibit a similar spatial distribution pat- tern. Both reconstructions show that the cropland was mostly found in the southern and eastern parts of the Songnen Plain. The two reconstructions matched each other for about 68% of the total cropland area. By spatially comparing the unmatched cropland cells of the two reconstructions with the settlements for each county, we found that unmatched cropland cells from method I are closer to settlements than those from method I1. This finding suggests that reconstruction using method I may have less bias than reconstruction with method I1.
文摘China Mobile Profits Soar on Record Subscriber Growth;Beijing Airport Axes Hundreds of Flights;Citigroup Extends Private Banking Reach in China;Shenzhen Development Bank in RMB 7bn Bond Sale;Google Ramps up China Presence with Tianya Stake;
