This paper presents numerical simulation results from a set of control and sensitivity experiments on the effects of winter-time air-sea interaction on the variability of sea surface temperature (SST) on a two-dimensional continental shelf which is uniform in the along-shore direction and is bounded to the west by a straight coast and to the east by a prescribed Gulf Stream front. In the control experiment, the model ocean circulation is driven by a time-dependent wind forcing which is parameterically coupled to the cross-shelf SST gradient. In the sensitivity experiments, wind stress, diabatic cooling and air-sea coupling are turned on separately to estimate the individual contribution of each effect to the cross-shelf SST variation. Experiments have also been carried out for different coupling strengths and diabatic cooling rates to examine the model sensitivity to these paramenters. The model results indicate that air-sea interaction could induce a secondary SST front on the shelf. Comparisons of model results with observations obtained during the Genesis of Atlantic Lows Experiment conducted off the east coasts of the Carolinas during January and February 1986 qualitatively confirm our finding. 相似文献
Journal of Material Cycles and Waste Management - Chemical looping hydrogen generation using iron oxides as oxygen carriers is a novel technology to convert carbonaceous substances into hydrogen.... 相似文献
Based on a survey of 107 farm households by means of participatory rural appraisal, this paper presents a region-level analysis of farmer's perception and response towards land policies and eco-environment in the Loess hilly area, China. The surveyed farmers are divided into two groups, farmers on non-irrigated farmland and farmers on irrigated farmland. The results indicate that most farmers mainly depend on cropland, especially the farmers on non-irrigated farmland. Farmers believe that stability and persistence of land policies are important, and most hold a positive attitude towards the Grain-for-Green Programme. The farmers on irrigated farmland have a more favourable attitude to environmental conservation than the farmers of non-irrigated farmland. Nearly 80% of interviewees consider that the local eco-environment has improved in the last ten years. About 45% never consider the environmental impact of their agriculture practices. About 55% think drought is the most important reason for eco-environment deterioration, overgrazing and serious soil erosion. Soil and water conservation is not conscious and voluntary behaviour for farmers, it is only a measure to guarantee their basic agricultural production and to improve their living conditions. Results indicate that farmers on nonirrigated land find engineering approaches more beneficial to agronomic methods. However, the farmers on irrigated farmland pay more attention to improving farmland quality. 相似文献
Subterranean clover and barley were grown on a soil derived from uranium mining debris and fertilized with phosphate as a U immobilizing additive for in situ remediation. We investigated the beneficial effect of P fertilization in the range 0-500 mg P kg(-1) soil in terms of U extractability, plant biomass production and U uptake. Increasing P in the mining debris caused a significant decrease of the water-soluble U and NH(4)-Ac extractable U at pH 7 and 5. For both plant species, P fertilization considerably increased root and shoot dry matter up to a maximum observed for soil receiving 100 mg P kg(-1) while the soil-to-plant transfer of U was regularly decreased by increasing P content in soil. These observations show that P fertilization represents an in situ practical option to facilitate the revegetation of U-mining heaps and to reduce the risks of biota exposure to U contamination. 相似文献
Polydopamine/NZVI@biochar composite (PDA/NZVI@BC) with high removal efficiency of tetracycline (TC) in aqueous solutions was successfully synthesized. The resultant composite demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance can be attributed to the presence of the huge surface area on biochar (BC), which could enhance NZVI dispersion and prolong its longevity. The carbonyl group contained on the surface of biochar could combine with the amino group on polydopamine(PDA). The hydroxyl groups in PDA is able to enhance the dispersion and loading of NZVI on BC. Being modified by PDA, the hydrophilicity of biochar was improved. Among BC, pristine NZVI and PDA/NZVI@BC, PDA/ NZVI@BC exhibited the highest activity for removal of TC. Compared with NZVI, the removal efficiency of TC could be increased by 55.9% by using PDA/NZVI@BC under the same conditions. The optimal modification time of PDA was 8h, and the ratio of NZVI to BC was 1:2. In addition, the possible degradation mechanism of TC was proposed, which was based on the analysis of degraded products by LC-MS. Different important factors impacting on TC removal (including mass ratio of NZVI to BC/PDA, initial concentration, pH value and the initial temperature of the solution) were investigated as well. Overall, this study provides a promising alternative material and environmental pollution management option for antibiotic wastewater treatment.
