Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

• UVA pre-irradiation to TiO₂ NPs enhanced its toxicity toward plant A. cepa. • UVA TiO₂ NPs increased intracellular ROS, resulting in more cell damage. • Cell death enhanced cell permeability and increased uptake of NPs. • Being highly toxic (EC₅₀ = 0.097 µmol/L), TC did not increase ROS generation. • Even at a low dose, TC enhanced the toxic potential of TiO₂ NPs significantly. Usage of titanium dioxide nanoparticles (TiO₂ NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa. Further, the toxicity of TiO₂ NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO₂ NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO₂), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC (EC₁₀ = 0.016 µmol/L) mixed with TiO₂ NPs significantly increased the toxicity for both UVA-TiO₂ and NI-TiO₂ NPs. Intracellular ROS generation was significantly high for UVA-TiO₂ NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential in A. cepa. Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO₂ NPs and TC showed the highest chromosomal aberrations (64.0%±1.26%) than the mixture with NI-TiO₂ or the individual contaminants. This decreased significantly after recovery (46.8%±1.92%), denoting the self-repair processes. This study proved that UVA-TiO₂ NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment.     

建筑施工安全事故损失内部化分析

当前,安全损失外部化倾向未能从根本上有效调动建筑企业致力于改善安全生产业绩。笔者认为,要从本质上改善我国建筑安全生产状况,必须促使安全损失内部化,该理念不仅有利于落实“企业安全生产责任主体”制度、保护建筑工人及其家庭的权益以及减轻政府负担,而且还能促使整个社会共同致力于改善职业安全与健康状况,从而促进建筑市场的持续健康发展和确保社会的和谐稳定。市场经济条件下,安全损失内部化须借助经济杠杆的调节作用,通过提高赔偿额度、提取安全生产抵押金、制裁或罚款、浮动保险费率、带薪工伤病假以及市场进退机制等手段,加大安全损失内部化力度。安全损失内部化力度的加大,对预防未来的安全事故将起到积极的经济刺激作用,从本质上提高我国建筑业整体安全管理水平。     

庇古税和排放量限制对环境污染外部性的作用机理

庇古税和排放量限制能促使环境污染外部性内部化,但只限于企业治理污染的成本低于环境成本时,且排放量限制比庇古税的效果差些.内部化后不仅可使企业的生产者剩余最大化,而且能使社会总剩余最大化.     

中国煤炭环境成本内部化的经济影响分析

对煤炭开采、运输和使用各个环节的环境污染和生态破坏外部成本进行核算的基础上,运用GREAT-E模型对煤炭环境成本内部化政策给GDP、居民收入、产业结构和贸易竞争力等带来的影响进行了定量分析.分析结果表明,煤炭开采、运输和使用各环节分别进行的环境成本内部化对中国宏观经济的影响较为有限,GDP的下降在可承受的范围之内,即使是全生命周期的煤炭环境成本完全内部化也只导致GDP出现0.15%左右的轻微下降.煤炭环境成本内部化将促进劳动力和资本等要素从高耗能行业向低耗能特别是技术密集型和现代服务业部门转移,进而推动产业结构优化转型升级.在煤炭生产、运输和消费环节通过征收环境相关税费能够更直接地刺激生产部门的环境行为调整,降低煤炭的生产和消费量,进而减少环境污染和生态破坏.     

交通拥挤负外部性产生的原因及内部化手段的环境经济学分析

应用微观经济学中的供需理论及环境经济学相关理论,从外部性理论的角度分析了城市道路交通拥挤产生的根本原因,将庇古税与补贴、科斯定理及政府管制应用于交通领域,并对这三种交通拥挤的负外部性内部化手段进行了环境经济学分析。     

中国的污染者负担原则演变综述

以考察污染者负担原则的起源为基础，从内涵、目的、负担范围和负担转移方式４方面剖析了污染者负担原则在我国的演变过程，从中阐述其在环境保护管理中的重要意义。