新型自贸协定的环保议题谈判及我国的对策简

自由贸易协定中纳入环境保护规定是提高自由贸易中的正环境效应,同时避免或减轻负面环境影响的保障,已经逐渐成为新型国际自由贸易谈判中的重要内容。以跨太平洋战略经济伙伴关系协定为代表的新型自由贸易谈判,试图在协定中丰富环境条款,例如环保原则、国际环境公约、环境标准、争端解决机制、环境产业和服务、环境合作和能力建设等。我国也开始在自贸谈判中纳入环保要求,基于最新的政策要求,我国应积极赶上国际自由贸易谈判中环境保护的新要求,推动贸易与环保政策的深度融合。     

Theoretical insights into the degradation mechanisms, kinetics and eco-toxicity of oxcarbazepine initiated by OH radicals in aqueous environments

As an anticonvulsant, oxcarbazepine (OXC) has attracted considerable attention for its potential threat to aquatic organisms. Density functional theory has been used to study the mechanisms and kinetics of OXC degradation initiated by OH radicals in aqueous environment. A total of fourteen OH-addition pathways were investigated, and the addition to the C8 position of the right benzene ring was the most vulnerable pathway, resulting in the intermediate IM8. The H-abstraction reactions initiated by OH radicals were also explored, where the extraction site of the methylene group (C14) on the seven-member carbon heterocyclic ring was found to be the optimal path. The calculations show that the total rate constant of OXC with OH radicals is 9.47 × 10⁹ (mol/L)⁻¹sec⁻¹, and the half-life time is 7.32 s at 298 K with the [·OH] of 10⁻¹¹ mol/L. Moreover, the branch ratio values revealed that OH-addition (89.58%) shows more advantageous than H-abstraction (10.42%). To further understand the potential eco-toxicity of OXC and its transformation products to aquatic organisms, acute toxicity and chronic toxicity were evaluated using ECOSAR software. The toxicity assessment revealed that most degradation products such as OXC-2OH, OXC-4OH, OXC-1O-1OOH, and OXC-1OH' are innoxious to fish and daphnia. Conversely, green algae are more sensitive to these compounds. This study can provide an extensive investigation into the degradation of OXC by OH radicals and enrich the understanding of the aquatic oxidation processes of pharmaceuticals and personal care products (PPCPs).     

Y chromosome detection by Real Time PCR and pyrophosphorolysis-activated polymerisation using free fetal DNA isolated from maternal plasma

Objectives To validate the use of Real Time PCR, a widely used technique that can detect very low levels of Y chromosomal sequence, and to assess the use of a highly sensitive PCR technique, pyrophosphorolysis-activated polymerisation (PAP), for fetal sex determination using free fetal DNA (ffDNA). Methods The fetal sex was determined by Real Time PCR in 58 pregnancies using ffDNA isolated from maternal plasma. In parallel with the Real Time PCR experiments, the presence of Y chromosome sequence was also determined using PAP on 54 isolated ffDNA samples. Results Both techniques detected Y chromosome sequence at very low levels with 98% specificity and 100% sensitivity (Real Time n = 44, PAP n = 54). Furthermore, the PAP technique was shown to be more robust than the Real Time PCR as none of the samples tested failed to meet the acceptance criteria. Combining the two techniques for male fetal sex detection from maternal blood plasma increases the sensitivity and specificity to 100% in this series. Conclusions This study shows that both Real Time PCR and PAP can be used for Y chromosome detection on ffDNA. Furthermore, by using PAP in combination with Real Time PCR more reliable early prenatal sexing can be performed using ffDNA. Copyright © 2007 John Wiley & Sons, Ltd.     

Between pregnancy biological variability of first trimester markers of Down syndrome: implications for screening in subsequent pregnancies

In a group of 149 women who had undergone routine first trimester screening using fetal nuchal translucency thickness (NT) and maternal serum free β-hCG and pregnancy associated plasma protein-A (PAPP-A) in two consecutive pregnancies the within person between pregnancy biological variability of these markers has been assessed. For fetal NT there was no correlation between NT MoM in the first and second pregnancy (r=0.0800). For maternal serum free β-hCG MoM a significant correlation was observed (r=0.4174) as was also found for PAPP-A MoM (r=0.3270). The implications for such between pregnancy marker association is that women who have an increased risk of Down syndrome in their first pregnancy are 1.5–2 times more likely to repeat this event in their next pregnancy. This observation may be useful in counselling women in the first trimester screening of a subsequent pregnancy. Copyright © 2001 John Wiley & Sons, Ltd.     

超声波/零价铁协同体系作用机理探讨

在超声波/零价铁协同体系中,探讨了OH.的产生途径及其影响因素,并分析了Fe0表面形态变化。结果表明:在超声波/零价铁体系中,羟基自由基的产生途径主要有四种:声空化导致水分子热解、Fenton反应、超声波与类Fenton反应的复合效应、铁粉颗粒效应;pH值过低或过高都不利于羟基自由基产生;当铁粉投加量为2.0g/L时最有利于羟基自由基产生;超声波通过冲刷、碎裂、清洗、气蚀和熔合等多种效应,活化和增强铁粉的表面性能。     

光助芬顿反应催化降解气体中甲苯

以甲苯作为挥发性有机污染物(VOCs)的代表,利用连续进气动态实验装置,研究光助芬顿反应降解气体中甲苯的作用.考察了芬顿试剂溶液初始p H、H2O2浓度、Fe2+浓度以及甲苯初始浓度对降解甲苯的影响,并利用在线质谱和色谱对产物进行了定性、定量分析.结果表明,紫外光照加快了羟基自由基的生成,显著提高了气体中甲苯的去除率;p H=3.0、H2O2浓度为20 mmol·L-1、Fe2+浓度为0.3 mmol·L-1的条件下,甲苯去除率最高;当甲苯初始浓度为260 mg·m-3时,去除率能够达到98%;光助芬顿反应催化降解气体中甲苯实验未检测到CO2之外的中间产物,CO2产率分析表明去除的甲苯全部转化为CO2.     

紫外辐射H2O2与PMS氧化准好氧矿化垃圾床渗滤液尾水

采用紫外（UV）活化双氧水（H₂O₂）和过一硫酸盐（PMS）产生活性氧物种降解准好氧矿化垃圾床渗滤液尾水中有机污染物.结果表明,紫外辐射双氧水（UV-H₂O₂）和紫外辐射过一硫酸盐（UV-PMS）体系对有机污染物的降解相比于单独体系效果显著.初始pH值和氧化剂投加量能够显著影响2种体系的降解效能,增加氧化剂投加量能够一定程度提高2种体系对渗滤液尾水中有机物的去除;2种体系均在酸性条件下效果较好,初始pH值的升高对2种体系过程有机物降解有抑制作用并且对UV-H₂O₂体系的抑制尤为显著.在最优条件下（初始pH值为3,氧化剂投量为0.084mol/L）,UV-H₂O₂与UV-PMS体系处理后出水COD去除率分别达到了72.09%和56.22%.另外,UV-H₂O₂体系中主要活性氧物种是羟基自由基,而UV-PMS体系中主要是由羟基自由基和硫酸根自由基的共同作用.紫外-可见光谱与三维荧光光谱表明两体系中均能降解渗滤液尾水中难降解芳香类有机物质,并且UV-PMS较UV-H₂O₂体系对腐殖质的反应速率更快,但是两种体系对渗滤液尾水中腐殖质的降解途径存在显著差异.研究结果可为光化学氧化处理垃圾渗滤液中难降解有机物提供参考.