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91.
The release of biochar colloids considerably affects the stability of biochar in environment. Currently, information on the release behavior and suspension stability of biochar colloids in real soil solutions is scarce. In this study, 20 soils were collected from different districts in China and the release behavior of biochar colloids and their suspension stability in soil solutions were systematically examined. The results showed that both pyrolysis temperature and biomass source had important effects on the formation of biochar colloids in soil solutions. The formation amount of biochar colloids from low pyrolysis temperatures (400 °C) (average amount of 9.33–16.41 mg/g) were significantly higher than those from high pyrolysis temperatures (700 °C) (average amount of less than 2 mg/g). The formation amount of wheat straw-derived biochar colloids were higher than those of rice straw-derived biochar colloids probably due to the higher O/C ratio in wheat-straw biochar. Further, biochar colloidal formation amount was negatively correlated with comprehensive effect of dissolved organic carbon, Fe and Al in soil solutions. The sedimentation curve of biochar colloids in soil solutions is well described by an exponential model and demonstrated high suspension stability. Around 40% of the biochar colloids were maintained in the suspension at the final sedimentation equilibrium. The settling efficiency of biochar colloids was positively correlated with comprehensive effect of the ionic strength and K, Ca, Na, and Mg contents in soil solutions. Our findings help promote a deeper understanding of biochar loss and stability in the soil-water environment. 相似文献
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水生态文明建设是一项长期且复杂的系统工程,需要全社会的协同努力,尤其需要公众的广泛参与.在剖析水生态文明定义及内涵的基础上,对巢湖生态文明先行示范区水生态文明建设中公众参与的困境进行分析与评估,从完善法律制度;强化宣传教育;渠道及反馈机制的构建;推动非政府组织发展等角度提出完善该地区水生态文明建设中公众参与的机制和对策,为其他地区公众参与水生态文明建设提供借鉴和思路. 相似文献
95.
我国以行政命令手段为主的环境管理措施并不能完全有效控制环境汞污染,因而有必要引入环境经济手段。本文基于汞在采掘、冶炼和产品生产三个生产环节中的利用、处置与排放特征,构建了经济系统及行业部门的汞物质平衡模型,并发现,单个污染源的汞污染物治理难以保证消除汞的环境危害。因而,采取环境经济手段控制工业汞污染,尽可能少的向环境中排放汞,在涉汞工业系统的层面上提高汞的利用效率和再资源化率。我国工业汞污染防治的环境经济手段包括环境污染价格、税费以及绿色金融两大类,但仅对生产环节高浓度汞排放发挥作用,对于堆存、再提取和处置环节的汞排放则作用不大。对此,应从扩大环境税(排污费)的征收范围,建立长效的绿色金融机制和推进第三方治理低含量含汞废物,这三个方面加以改进。 相似文献
96.
污染物总量减排中的问题和对策 总被引:1,自引:0,他引:1
“十一五”全国主要污染物排放总量减少10%已成为约束性指标。面对严峻的形势,尽管社会各界空前重视,但各地减排工作进展不平衡,仍存在经济增长方式粗放、政策措施落实不到位等问题。针对存在的问题,提出了加大产业结构调整力度、污染防治资金投入、实施严格的环境准入制度等政策措施。完善减排体系、适时修改国家污染减排核算细则等技术措施,加大环境执法和环境监管力度、减排宣传力度等保障措施。 相似文献
97.
朱绍霞 《防灾科技学院学报》2006,8(1):138-139
在听、说、读、写、译五种技能中,听占首位,可见其重要性。但是对我校大多数学生来说,听力是最难的科目。听力的薄弱制约了学生其他各项能力的提高。本文分析了我校学生听力中存在的问题,分析了这些问题存在的原因,并就这些问题的解决提出了相应的建议。 相似文献
98.
Hung-Yi Hou Chung-Hwei SuChi-Min Shu 《Journal of Loss Prevention in the Process Industries》2012,25(1):176-180
Many studies have been performed to clarify the basic thermal runaway hazards and kinetics of cumene hydroperoxide (CHP) decomposition. However, materials that are incompatible with CHP have not been clearly identified. Alkaline solutions have been used as a catalyst to form dimethylphenyl carbinol (DMPC) and dicumyl peroxide (DCPO); however, these solutions also affect the reaction and storage temperature of CHP. In this study, thermal calorimeters, differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), were used to compare the effects of various bases on the decomposition of CHP in cumene. Specifically, the exothermic onset temperature, change in pressure over time, self-heating rate and heat of decomposition were evaluated. Moreover, to appraise the degree of hazard associated with the use of CHP, the compatibility of CHP with various substances was analyzed, and a risk matrix for thermal runaway reactions was obtained. The results of the present study could be used to design safety procedures for the production of CHP and its derivatives. 相似文献
99.
Gudbjerg J Trötschler O Färber A Sonnenborg TO Jensen KH 《Journal of contaminant hydrology》2004,75(3-4):297-318
Numerical simulation of steam injection into a water-saturated porous medium may be hindered by unphysical behavior causing the model to slow down. We show how spurious water flow may arise on the boundary between a steam zone and a saturated zone, giving rise to dramatic pressure drops. This is caused by the discretization of the temperature gradient coupled with the direct relation between pressure and temperature in the steam zone. The problem may be a severe limitation to numerical modeling. A solution is presented where the spurious water flow is blocked and this widely enhances the performance of the model. This new method is applied to a previously reported example exhibiting numerical problems. Furthermore, it is applied to the simulation of 2-D sandbox experiments where LNAPL is remediated from a smearing zone by steam injection. These experiments would have been difficult to analyze numerically without the adjustment to prevent spurious flow. 相似文献
100.
裴艳丽 《中国环境管理干部学院学报》2007,17(3):113-114
针对大学生听力存在问题进行分析,从师生教与学两个角度提出了相应的对策,选择适合学生水平的听力资料,激发听力兴趣,树立听力信心,进行多途径的听力训练,养成良好的听力和英语思维习惯,增强语言运用的频率等,以期达到语言学习的目的。 相似文献