Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to est... 相似文献
Microbial activity may influence phosphorus (P) deposit and release at the water sediment interface. The properties of DO (dissolved
oxygen), pH, P fractions (TP, Ca-P, Fe-P, OP, IP), and APA (alkaline phosphatase activity) at the water sediment interface were measured
to investigate microbial activity variations in surface sediment under conditions of two-month intermittent aeration in overlying water.
Results showed that DO and TP of overlying water increased rapidly in the first week and then decreased gradually after 15 day of
intermittent aeration. Microorganism metabolism in surface sediment increased pH and decreased DO and TP in the overlying water.
After two-month intermittent aeration, APA and OP from surface sediment (0–2 cm) were both significantly higher than those from
bottom sediment (6–8 cm) (p < 0.05), and surface sediment Fe-P was transferred to OP during the course of microorganism reproduction
on the surface sediment. These results suggest that microbial activity and microorganism biomass from the surface sediment were higher
than those from bottom sediment after two-month intermittent aeration in the overlying water. 相似文献
Various methods for shifting the optical response of TiO2 into the visible (Vis) range have been reported. Herein, we reported the application of a TiO2/H2O2/Vis process and the effects of TiO2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO2 crystalline structure and H2O2 addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H2O2 addition after 180?min of reaction, the synergistic degradation of terbuthylazine by TiO2-Fe3 + was substantially accelerated, with the degradation rate reaching up to 100% after 20?min of reaction, and rutile TiO2 showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO2. The addition of free-radical scavengers (tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO2, but had a relatively minor effect on anatase TiO2. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO2 as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO2 occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO2. This study provides new insight into the role of TiO2 crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism. 相似文献
Ordered mesoporous carbon(OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound(VOC)disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal. 相似文献
Incompatible polypropylene (PP) and polyethylene (PE) are difficult to separate in mixed recycling streams such as waste plastic packaging, which makes polyolefin mixtures unsuitable for high-quality products. In this work, based on the free radical branching reaction, a co-branching reaction of isotactic polypropylene (iPP) and high-density polyethylene (HDPE) blends was carried out in the presence of the peroxide, free radical regulator and multifunctional acrylate monomer, and a star-like long-chain branching (LCB) copolymer was obtained. The effect of in situ compatibilization on the structures and mechanical properties of iPP/HDPE was investigated, and the compatibilization mechanism was discussed. Results showed that the mechanical properties of the modified blends were largely improved, and efficient in-situ compatibilization of iPP and HDPE could be taken place in a wide process window. Moreover, the sizes of the dispersed phase in the modified blends were clearly decreased, and the interfacial thickness increased. Compared with the pure iPP/HDPE blend, the initial crystallization temperature of iPP in the modified iPP/HDPE blend was increased, and long branched chains of the LCB copolymers were physically entangled with the chemical identical homopolymers or even participated in the crystallization of iPP and HDPE. Thanks to the in situ compatibilization strategy, the compatibility of iPP/HDPE was significantly improved.