The pH effect on the sorption kinetics of heavy metals in soils was studied using a Constant flow leaching method. The soil samples were red soil collected from Yingtan, Jiangxi, and yellow-browp soil from Nabing,Jian...The pH effect on the sorption kinetics of heavy metals in soils was studied using a Constant flow leaching method. The soil samples were red soil collected from Yingtan, Jiangxi, and yellow-browp soil from Nabing,Jiangsu. The heavy metals tested were zinc and cadmium.Assuming that the experimental data fitted to the following kinetic rate equation: 1/c dx/dt=kx∞-kx,the rate constant k of sorption could be determined from the slope of the straight line by plotting of 1/c.dx/dt vs. x. The results showed that the pH effect on the rate constants of heavy mental sorption in soils was very significant. The values of k decreased with inpeasing pH. The sorptions were more sensitive to pH in red soil than in yellow-brown soil.展开更多
With the aid of the Remote Sensing (RS) and Geographic Information System (GIS) technology, the eco-system pattern and fragility distribution maps of the 50-km-wide zone along the Qinghai-Tibet Railway were com-piled ...With the aid of the Remote Sensing (RS) and Geographic Information System (GIS) technology, the eco-system pattern and fragility distribution maps of the 50-km-wide zone along the Qinghai-Tibet Railway were com-piled and by using the superimposition method, range, area and indexes of the impact of various engineering activities on the ecosystems alongside the railway were studied. By making reference to the ecosystem recovery process of the Qinghai-Tibet Highway, mechanisms of recovery of the al-pine ecosystems alongside the Qinghai-Tibet Railway were studied and extents and rates of the recovery were predicted. The results indicate that the impact of the railway engineer-ing on the Alpine ecosystem depends mainly on how much the original surface soil in the zone has been disturbed and how fragile of the ecosystem per se. Restoration of vegetation coverage and species abundance shows a significantly reverse relationship with disturbance of the original surface soil but an extremely positive one with the length of the restoration period and mean annual precipitation and annual mean rela-tive humidity in the period and no obvious bearings with altitude and temperature. In sections with an annual pre-cipitation over 200 mm, as long as a certain percentage of original soil is left in situ, it takes only 30 years or so for bio-diversity to get basically restored to the original level after the construction is completed but at least 45—60 years or more for vegetation coverage.展开更多
文摘The pH effect on the sorption kinetics of heavy metals in soils was studied using a Constant flow leaching method. The soil samples were red soil collected from Yingtan, Jiangxi, and yellow-browp soil from Nabing,Jiangsu. The heavy metals tested were zinc and cadmium.Assuming that the experimental data fitted to the following kinetic rate equation: 1/c dx/dt=kx∞-kx,the rate constant k of sorption could be determined from the slope of the straight line by plotting of 1/c.dx/dt vs. x. The results showed that the pH effect on the rate constants of heavy mental sorption in soils was very significant. The values of k decreased with inpeasing pH. The sorptions were more sensitive to pH in red soil than in yellow-brown soil.
文摘With the aid of the Remote Sensing (RS) and Geographic Information System (GIS) technology, the eco-system pattern and fragility distribution maps of the 50-km-wide zone along the Qinghai-Tibet Railway were com-piled and by using the superimposition method, range, area and indexes of the impact of various engineering activities on the ecosystems alongside the railway were studied. By making reference to the ecosystem recovery process of the Qinghai-Tibet Highway, mechanisms of recovery of the al-pine ecosystems alongside the Qinghai-Tibet Railway were studied and extents and rates of the recovery were predicted. The results indicate that the impact of the railway engineer-ing on the Alpine ecosystem depends mainly on how much the original surface soil in the zone has been disturbed and how fragile of the ecosystem per se. Restoration of vegetation coverage and species abundance shows a significantly reverse relationship with disturbance of the original surface soil but an extremely positive one with the length of the restoration period and mean annual precipitation and annual mean rela-tive humidity in the period and no obvious bearings with altitude and temperature. In sections with an annual pre-cipitation over 200 mm, as long as a certain percentage of original soil is left in situ, it takes only 30 years or so for bio-diversity to get basically restored to the original level after the construction is completed but at least 45—60 years or more for vegetation coverage.
