The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, a...The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, as an agricultural fertilizer. The agricultural soil amended with 250 g kg^-1 sewage sludge with or without lime treatment was used for the growth of the common local grain crop, maize （Zea maize）. The mobility of the trace and toxic metals in the sludge samples was assessed by applying a modified BCR sequential extraction procedure. The single extraction procedure was comprised of the application of a mild extractant （CaCl2） and water, for the estimation of the proportion of easily soluble metal fractions. To check the precision of the analytical results, the concentrations of trace and toxic metals in every step of the sequential extraction procedure were summed up and compared with total metal concentrations. The plant-available metal contents, as indicated by the deionized water and 0.01 mol L^-1 CaCl2 solution extraction fractions and the exchangeable fraction of the sequential extraction, decreased significantly （P 〈 0.05） with lime application because of the reduced metal availability at a higher pH, except in the cases of Cd and Cu, whose mobility was slightly increased. Sludge amendment enhanced the dry weight yield of maize and the increase was more obvious for the soil with lime treatment. Liming the sewage sludge reduced the trace and toxic metal contents in the grain tissues, except Cu and Cd, which were below the permissible limits of these metals. The present experiment demonstrates that liming was an important factor in facilitating the growth of maize in sludge-amended soil.展开更多
Chromium nitride （Cr2N） thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300℃, and its influence on the film structure and refractive index was inves...Chromium nitride （Cr2N） thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300℃, and its influence on the film structure and refractive index was investigated. X-ray diffraction analysis shows that the crystalline strucure of the films transforms from the （101） to （002） oriented hexagonal CrzN phase as the increase of substrate tempera- ture above 50℃, and a highly texatred film grows at 100℃. An empirical relation between the crystalline orientation and infrared active modes of the films is obtained, i.e., the Fourier transform infrared （FTIR） spectrum of the film prepared at 50℃ exhibits only A1 （TO） mode. The prominent peak in the FTIR spectra of the film prepared above 50℃is assigned to the E1 （TO） mode and is correlated with the （002） or c-axis oriented hexagonal wurtzite phase of Cr2N. In the surface analysis of atomic force microscopy, a transformation from the featureless surface to columnar-type morphology is observed with the increase of substrate temperature from 50 to 100℃, exhibiting c-axis oriented crystallite growth. A further increase in substrate temperature to 200℃ causes the c-axis crystallites to merge, resulting in the formation of voids. The refractive index （n） of the deposited films is obtained using spectroscopic ellipsometry.展开更多
文摘The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, as an agricultural fertilizer. The agricultural soil amended with 250 g kg^-1 sewage sludge with or without lime treatment was used for the growth of the common local grain crop, maize （Zea maize）. The mobility of the trace and toxic metals in the sludge samples was assessed by applying a modified BCR sequential extraction procedure. The single extraction procedure was comprised of the application of a mild extractant （CaCl2） and water, for the estimation of the proportion of easily soluble metal fractions. To check the precision of the analytical results, the concentrations of trace and toxic metals in every step of the sequential extraction procedure were summed up and compared with total metal concentrations. The plant-available metal contents, as indicated by the deionized water and 0.01 mol L^-1 CaCl2 solution extraction fractions and the exchangeable fraction of the sequential extraction, decreased significantly （P 〈 0.05） with lime application because of the reduced metal availability at a higher pH, except in the cases of Cd and Cu, whose mobility was slightly increased. Sludge amendment enhanced the dry weight yield of maize and the increase was more obvious for the soil with lime treatment. Liming the sewage sludge reduced the trace and toxic metal contents in the grain tissues, except Cu and Cd, which were below the permissible limits of these metals. The present experiment demonstrates that liming was an important factor in facilitating the growth of maize in sludge-amended soil.
基金financially supported by the National Institute of Laser and Optronics(NILOP)
文摘Chromium nitride （Cr2N） thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300℃, and its influence on the film structure and refractive index was investigated. X-ray diffraction analysis shows that the crystalline strucure of the films transforms from the （101） to （002） oriented hexagonal CrzN phase as the increase of substrate tempera- ture above 50℃, and a highly texatred film grows at 100℃. An empirical relation between the crystalline orientation and infrared active modes of the films is obtained, i.e., the Fourier transform infrared （FTIR） spectrum of the film prepared at 50℃ exhibits only A1 （TO） mode. The prominent peak in the FTIR spectra of the film prepared above 50℃is assigned to the E1 （TO） mode and is correlated with the （002） or c-axis oriented hexagonal wurtzite phase of Cr2N. In the surface analysis of atomic force microscopy, a transformation from the featureless surface to columnar-type morphology is observed with the increase of substrate temperature from 50 to 100℃, exhibiting c-axis oriented crystallite growth. A further increase in substrate temperature to 200℃ causes the c-axis crystallites to merge, resulting in the formation of voids. The refractive index （n） of the deposited films is obtained using spectroscopic ellipsometry.
