不同类型地膜覆盖对土壤质量、根系生长和产量的影响

针对我国农业生产中地膜大规模使用带来的土壤环境污染问题,通过应用降解地膜进行大田试验,以南瓜为研究试材,探究了黑色普通地膜(CK)、白色降解地膜(WDF)、黑色降解地膜(BDF)和黑色CO₂基降解地膜(C-DF)对土壤理化性质、根系生长与产量的影响,并对土壤质量进行评估.结果表明,3种降解地膜处理土壤含水量和温度,较普通地膜均不同程度降低;各处理间土壤有机质含量无显著差异;C-DF处理土壤速效钾含量较CK降低,WDF和BDF无显著影响;BDF和C-DF处理土壤全氮和速效氮含量较CK和WDF降低,处理间差异达到显著水平.3种降解膜处理土壤过氧化氢酶活性较CK显著提升2.9%～6.8%,蔗糖酶较CK显著降低了33.3%～38.4%.BDF处理土壤纤维素酶活性较CK显著提升63.8%,WDF和C-DF无显著影响.3种降解膜处理对地下部根系生长具有促进作用,长势明显增强.BDF和C-DF处理南瓜产量与CK趋近,BDF处理南瓜产量较CK显著降低11.4%.试验结果表明,BDF和C-DF处理对土壤质量和产量的影响与CK相当.研究认为2种黑色的降解地膜在高温生产季节可有效替代普...     

Comparison of properties of traditional and accelerated carbonated solidified/stabilized contaminated soils

The investigation of the long-term performance of solidified/stabilized (S/S) contaminated soils was carried out in a trial site in southeast UK. The soils were exposed to the maximum natural weathering for four years and sampled at various depths in a controlled manner. The chemical properties (e. g. , degree of carbonation (DOC), pH, electrical conductivity (EC)) and physical properties (e. g. , moisture content (MC), liquid limit (LL), plastic limit (PL), plasticity index (PI)) of the samples untreated and treated with the traditional and accelerated carbonated S/S processes were analyzed. Their variations on the depths of the soils were also studied. The result showed that the broad geotechnical properties of the soils, manifested in their PIs, were related to the concentration of the water soluble ions and in particular the free calcium ions. The samples treated with the accelerated carbonation technology (ACT), and the untreated samples contained limited number of free calcium ions in solutions and consequently interacted with waters in a similar way. Compared with the traditional cement-based S/S technology, e. g. , treatment with ordinary portland cement (OPC) or EnvirOceM, ACT caused the increase of the PI of the treated soil and made it more stable during long-term weathering. The PI values for the four soils ascended according to the order: the EnvirOceM soil, the OPC soil, the ACT soil, and the untreated soil while their pH and EC values descended according to the same order.     

规范农田土壤修复项目管理提升农田土壤修复内涵

实现土壤修复项目的规范管理,对于提升农田土壤修复内涵、提高土地资源利用效率具有重大影响。本文在阐述农田土壤修复内涵及必要性的同时,对土壤修复项目管理中的问题进行分析,并提出当前农田土壤修复质量提升策略。期望有利于土壤修复项目的规范管理,进而提升土地资源利用效率。     

油气田瓦斯隧道开挖掌子面围岩安全厚度研究

为降低油气田区隧道施工风险，以龙泉山隧道为依托，采用数值模拟方法对隧道开挖掌子面前方围岩安全厚度进行分析，并结合现场监测数据对所得结论进行验证。研究结果表明:隧道施工使隧址区围岩应力重分布，且应力变化与围岩距掌子面距离L有关，当L≤0.75D（D为隧道净高）时，围岩处于应力释放区；当0.75D相似文献   

Effect of aging level on viscoelastic properties of asphalt binder containing waste polyethylene

Due to inherent advantages, waste polyethylene (generated from domestic sources) has been used as asphalt modifier. This article discusses viscoelastic properties of the polyethylene modified asphalt binder. Several asphalt concrete mixtures were designed by varying polyethylene and asphalt content. Shredded polyethylene incorporated into asphalt concrete by dry mixing process. Using optimised asphalt content (at several polyethylene percentages), mixtures were prepared and compacted. These compacted specimens were aged for different duration in convection oven. Asphalt binder (from aged specimens) was extracted and tested for its viscoelastic properties using dynamic shear rheometer. Comparison of mastercurves indicated increase in complex modulus and decrease in phase angle values with addition of polyethylene at all reduced frequencies. However, the extent of change was highly dependent on frequency, aging duration and polyethylene content. This indicates that the addition of polyethylene provides more resilience to asphalt binder especially with less aging time. Storage modulus mastercurves (at lower frequencies) and relaxation modulus values (at longer time) indicate polyethylene provides additional stiffening to binder. Further, changes in viscous modulus with addition of polyethylene were marginal. Overall results indicate that waste polyethylene improves the properties of asphalt binder over extended loading period when heated for less time during mixing.     

塑料排水板超载预压法在顺德市道路建设中的应用

采用塑料排水板超载预压法进行特殊路基的设计和施工,并通过对软土路基的变形监测结果进行了分析,评价其安全性。监测结果分析表明．在等量超填土4．5t／m^2预压3个月后固结度普遍达到85％以上,软土路基固结速度很快,且路基在堆载过程中是安全稳定的。实践证明,用塑料排水板超载预压法处理深达20余米、承载力极低的淤泥质粉质粘土排水效果明显,设计与施工方案是可行的。     

高炉喷吹废塑料技术

废旧塑料造成的“白色污染”成为除大气}亏染和水污染之外的第三大污染。废旧塑料是高分子碳氢化合物,将其作为替代煤粉或重油的燃料喷吹进入高炉,既能降焦节能,又能保护环境。介绍了国外应用高炉喷吹废塑料技术的情况并分析了该技术在我国应用的可行性。     

新疆阿瓦提县废旧地膜回收利用研究

阿瓦提县地膜的过量使用使当地土壤环境逐渐恶化,严重污染了农村环境,并影响了农机作业质量的提高。通过分析2011年阿瓦提县地膜使用相关数据及地膜回收利用情况,提出了阿瓦提县地膜回收利用的优化对策:加大对"白色污染"危害性的宣传,提升广大农民群众的生态文明意识;发展废旧地膜回收利用企业,拓宽回收渠道;制定优惠政策,加大支持力度,促进废旧地膜回收利用;从农艺上防治和减少地膜残留;采取人工和机械回收相结合的措施,加大残留地膜回收力度。     

Consumer willingness to pay for plastic bags levy and willingness to accept eco-friendly alternatives in Botswana

Plastic bags, though commonly used for packaging of goods, are highly durable and non-biodegradable. Plastic bag litter serves as a negative environmental externality detrimental to animal health and natural beauty of the environment. In an effort to curtail the excessive use of plastic bags in Botswana, the government introduced a plastic levy targeted at consumers at retail points. This study uses primary data collected from 367 respondents randomly selected from six geospatially and purposively selected shopping malls to determine the consumers’ willingness to pay (WTP) for continued plastic bag usage and their willingness to accept (WTA) to shift to eco-friendly alternatives. The results of the study revealed that open dumping and burning of plastic litter are more common in Maun than in Gaborone. It also showed that there is a significant relationship between the level of education and WTP. Further, there is a significant variation in income and education in respect to environmental awareness. The government should improve its efforts of sensitizing the public about the improper disposal of plastic bags.     

负载型TiO2-xNx的制备表征及可见光催化降解亚甲基蓝

以溶胶-凝胶法制备TiO2溶胶,负载于玻璃微珠表面,在NH3气流中直接进行热处理,制备负载型掺氮纳米TiO2薄膜催化剂.选取亚甲基蓝为处理对象,结合对催化剂表面结构、晶型和紫外可见吸收的表征,对制备的催化剂进行评价.结果表明,450℃下焙烧3 h所制备的负载型催化剂为锐态矿相;可见光的范围拓展到700 nm左右;负载均...