An empirical investigation of construction and demolition waste generation rates in Shenzhen city, South China

The construction and demolition waste generation rates (C&D WGRs) is an important factor in decision-making and management of material waste in any construction site. The present study investigated WGRs by conducting on-site waste sorting and weighing in four ongoing construction projects in Shenzhen city of South China. The results revealed that WGRs ranged from 3.275 to 8.791 kg/m² and miscellaneous waste, timber for formwork and falsework, and concrete were the three largest components amongst the generated waste. Based on the WGRs derived from the research, the paper also discussed the main causes of waste in the construction industry and attempted to connect waste generation with specific construction practices. It was recommended that measures mainly including performing waste sorting at source, employing skilful workers, uploading and storing materials properly, promoting waste management capacity, replacing current timber formwork with metal formwork and launching an incentive reward program to encourage waste reduction could be potential solutions to reducing current WGRs in Shenzhen. Although these results were derived from a relatively small sample and so cannot justifiably be generalized, they do however add to the body of knowledge that is currently available for understanding the status of the art of C&D waste management in China.     

铬渣无害化处理技术研究进展

综述了铬渣无害化处理技术的研究进展,分析了各种技术在实际应用过程中的效果,指出各种处理技术的优缺点,详细介绍了固化法中水泥固化和药剂稳定化两种处理技术,提出开发重金属螯合剂是今后铬渣稳定化处理的研究方向.     

中国化肥面源污染EKC验证及其驱动因素

基于1990-2008年全国各省、市、自治区的面板数据,本文首先对中国化肥投入面源污染的库兹涅茨曲线进行验证,并对经济发展过程中我国化肥投入面源污染时空演变规律的驱动因素进行理论与定量探析,以期为协调农业环境与经济增长和谐发展,进而实现中国化肥投入面源污染库兹涅茨曲线的低值超越找寻政策着力点.结果表明,中国化肥投入面源污染与宏观经济增长之间存在典型的倒U型曲线的关系.在影响中国化肥投入面源污染时空演变的诸多因素中,居民收入水平和环境需求水平的提高,有利于降低农业环境的污染程度;农民非农就业程度的不断提高、城乡二元环境管理体制、蔬菜和瓜果类等经济作物的播种面积大幅度增长和复种指数的提高是中国化肥投入面源污染不断加剧的熏要原因.农业技术进步有利于降低中国化肥投入的面源污染,但由于中国农户的经营规模小和农业科技研发、推广和应用水平低下,使得农业技术进步环境效应并未得到充分发挥.     

环境规制和农业科技进步的关系分析——基于波特假说的研究

波特假说主要从动态的角度论证了环境规制和农业科技进步之间的正向变亿关系.而在安徽省1990 -2008年的农业生产数据的基础上,选择合适的环境规制和农业科技进步的指标变量,运用Johansen协整分析方法验证了安徽省农业生产中的环境规制和农业科技进步的关系也符合这一假说,Granger因果关系检验说明了安徽省环境规制是农业科技进步产生的原因,脉冲响应分析和方差分析则更深入地从定量的角度分析了环境规制对农业科技进步影响滞后的趋势和影响程度.由实证分析可以看出,只是从静态角度来分析,环境规制是不利于农业的科技进步的;但从长期效益来看,环境规制有利于农业的科技进步.因此,在农业生态环境恶化的形势下,严格对农业废弃物的排放限制,制定较严格的农产品生产标准和产品质量标准,提高农民的环境意识和科技意识,通过强化环境规制来促使农业生产者提高农业生产技术,提高农产品品质和产品的市场竞争力就显得尤为重要.     

Toxicity of various anions associated with methoxyethyl methyl imidazolium-based ionic liquids on Clostridium sp

We investigated the effects on the growth of the anaerobic bacterium, Clostridium sp., of the ionic liquid, 1-methoxyethyl-3-methyl imidazolium [MOEMIM]⁺, derived from imidazolium cation and paired with one of a variety of counter-ions, viz., tetrafluoroborate [BF₄]^-, hexafluorophosphate [PF₆]^-_, trifluoroacetate [CF₃COO]^-, bis(trifluoromethane)sulfonamide [Tf₂N]^-, methane sulfonate [OMS], and 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF₄]. These anions, in association with [MOEMIM]⁺ lowered the growth rate of the bacterium, showing the following trend: [Tf₂N]^- ≧ [PF₆]^- > [BF₄]^- > [CF₃COO]^- > [OMS]⁻. Anions incorporating fluorine were more toxic than those without it, and their toxicity rose with an increase in the number of fluorine atoms. Also, [MOEMIM]⁺[BF₄]^- was less toxic than [BMIM]⁺[BF₄]^-, probably due to the presence of a methoxyethyl functional group integrated in the cation side chain.     

Quantification of the inhibitory effect of methyl fluoride on methanogenesis in mesophilic anaerobic granular systems

The inhibitory effect of CH₃F on methanogenesis in mesophilic anaerobic granules was tested at different concentrations (0-10% v/v, in the gas phase) and verified by the stable carbon isotopic signatures of CH₄ and CO₂. The results showed that the inhibitory effect increased with the initial CH₃F concentration up to 5%. The CH₃F concentration causing 50% metabolic inhibition was 0.32%. Complete inhibition of acetoclastic methanogenesis with a 91% reduction in total methanogenic activity was achieved when 5% CH₃F was initially added to the headspace, which resulted in 870 μM dissolved CH₃F in the liquid. It was much higher than that applied in other natural anoxic non-granular systems, indicating that the layered granular structure influenced the inhibitory effect. The obvious increase in hydrogen content indicated that high concentrations of CH₃F (?5%) suppressed hydrogenotrophic methanogenesis as well. The stable inhibition lasted for at least 6 d as the CH₃F concentration decreased slowly with incubation time. These results suggested that CH₃F could be used for investigating methanogenic processes in anaerobic granular systems after the CH₃F concentration and incubation time for specific inhibition of acetoclastic methanogenesis were carefully determined. In the present system, CH₃F concentration of 5% was suggested to be optimal.     

乌江干流梯级电站生态调度现状分析

乌江是我国十三大水电基地之一,主要的开发任务为发电,其次为航运,兼顾防洪及其他。本研究在乌江干流上选取了4个具有代表性的断面,运用修正的Tennant法和综合法计算了维持乌江干流各代表性河段基本健康所需的生态需水量。研究表明,目前乌江干流梯级电站采取的调度措施能够满足各代表性河段所需的最小生态需水量。但目前的调度措施仍是建立在发电效益最大化基础上的,未能从干流生态环境系统的特殊要求进行调度,给干流生态环境造成了一定影响。本文最后提出了从多方面开展乌江干流梯级电站生态调度研究工作的建议。     

含钛炉渣制备光催化剂处理模拟甲基橙废水

以含钛炉渣为原料制得光催化剂PTC,PTC不仅对紫外光具有较大的吸收,且在可见光范围内也有明显的吸收。PTC是一种比表面积较大的多微孔材料。PTC对模拟甲基橙废水脱色的最佳工艺条件:PTC加入量为0.50g/L,废水pH为2。加入强氧化剂H2O2能提高模拟甲基橙废水的总脱色率,在初始质量浓度为50m g/L的模拟甲基橙废水中H2O2加入量为6m g/L时,废水总脱色率达80.96%,比不加H2O2时的废水总脱色率提高了31.36%。     

刚毛藻对Cu、Fe、Zn的耐受与污染控制研究

研究刚毛藻对Cu、Fe、Zn的耐受情况。实验设计了3种重金属的浓度,分别为00、.5 mg/L1、.0 mg/L、2.5 mg/L、5.0 mg/L、7.5mg/L1、0 mg/L的培养液,培养期间观察记录刚毛藻的长势,测定藻类生物量及叶绿素a的含量变化,研究藻体对模拟水中3种重金属的去除动态及实际去除效果。结果表明,3种重金属在低浓度(0.5—2.5 mg/L)时藻体长势较好;浓度达到5mg/L时开始出现毒害现象,表现为叶绿素a含量下降趋势;浓度达到7.5mg/L以上时藻体死亡。水体中有效Cu、Fe、Zn浓度较低时,藻体对3种重金属去除效果较好,较高浓度时由于毒害作用使其对3种重金属的去除能力下降。