Rapid treatment of atrazine-contaminated water by nickel/iron bimetallic system

The utility of nickel/iron in the remediation of atraz.ine-contaminated water was investigated. The experimental results showed that nickel/iron had effective catalytic activity in dechlorinating atraz.ine under acidic conditions. The dechlonnation reaction approximately followed the first-order kinetics under the experimental conditions( nickel/iron: 1.0 g/250 ml: Ca~r~ = 20.0 mg/L), the reaction rate increased with decreasing pH value of the reaction solution and increasing the proportion of Ni: Fe within 2.95 %. For condition with 2.95% nickel/iron, the reaction rate constants were 0.07518( R = 0.9927), 0.06212( R = 0.9846) and 0.00131 min^-1 ( R = 0.9.565) at pH = 2.0, 3.0 and 4.0, respectively. HPLC analysis was used to monitor the decline of atraz.ine concentration.     

Biogenic VOCs emission inventory development of temperate grassland vegetation in Xilin River basin, Inner Mongolia, China

Given the key role of biogenic volatile organic compounds(VOCs) to tropospheric chemistry and regional air quality, it is important to generate accurateVOCs emission inventories. However, only a less fraction of plant species, in temperate grassland of Inner Mongolia, has been characterized by quantitative measurements. A taxonomic methodology, which assigns VOCs measurements to unmeasured species, is an applicable and inexpensive alternation for extensive VOCs emission survey, although data are needed for additional plant families and genera to further validate the taxonomic approach in grassland vegetation. In this experiment, VOCs emission rates of 178 plant species were measured with a portable photoionization detector( PID). The results showed the most of genera and some families have consistent feature of their VOCs emission, especially for isoprene, and provide the basic premise of taxonomic methodology to develop VOCs emission inventories for temperate grassland. Then, the taxonomic methodology was introduced into assigning emission rate to other 96 species, which no measured emission rates available here. A systematical emission inventory of temperate grassland vegetation in Inner Mongolia was provided and further evidence that taxonomy relationship can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera to grassland vegetation.     

Pollution characteristics and health risk assessment of polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons during heating season in Beijing

Polycyclic aromatic hydrocarbons(PAHs) and their nitrated derivatives(NPAHs) attract continuous attention due to their outstanding carcinogenicity and mutagenicity. In order to investigate the diurnal variations, sources, formation mechanism, and health risk assessment of them in heating season, particulate matter(PM) were collected in Beijing urban area from December 26, 2017 to January 17, 2018. PAHs and NPAHs in PM were quantitatively analyzed via gas chromatography-mass spectrometry(GC-MS). ...     

跨音速风扇叶片高低转速下混合相积冰的对比研究

目的 获得跨音速风扇转子叶片高、低转速下混合相积冰的影响规律。方法 使用CFX获取风扇叶片空气流场数据,采用FENSAP-ICE获取积冰冰形,通过过冷水滴与冰晶温度、撞击叶片角度等进行混合相积冰高、低转速冰形分析。结果 风扇叶片高、低转速运转时,过冷水滴与冰晶的运动状态变化相对明显。高转速时,流场内的气流为跨音速流动,过冷水滴与冰晶撞击角度相差较大,撞击角度较大的叶根区域更容易收集过冷水滴与冰晶;低转速时,过冷水滴和冰晶与叶片的撞击角度大部分区域低于10°,使过冷水滴与冰晶碰撞到叶片后的捕获难度提升。风扇叶片高、低转速运转时,叶身的温度差异使过冷水滴在低转速下易直接凝结,未凝结的水膜量极少,而冰晶表面未形成水膜,不易被捕获,使得最终的积冰主要为过冷水滴积冰。结论 风扇叶片混合相积冰在高转速时,流道内温度升高更快,水膜不易凝结,冰晶表面易融化,促进了冰晶积冰。     

反硝化脱氮对太湖蓝藻水华态势的影响

反硝化作用是水生生态系统的主要脱氮过程,与蓝藻生长之间存在对氮素的竞争作用,然而气候变化背景下反硝化脱氮对蓝藻水华发生动态的影响仍不清楚.基于2017~2021年北太湖为期5 a的水质监测历史数据,结合不同温度下蓝藻生长和沉积物泥浆培养实验,探究了湖体反硝化脱氮与蓝藻水华之间的相互影响.监测数据表明,太湖水体藻类生物量（以Chla表示）高值主要出现在夏秋季节,而总氮浓度季节变化规律与藻类生物量完全相反,冬春季较高,夏秋季显著降低,溶解态无机氮主要以硝态氮为主,并且硝态氮浓度在夏秋季节几乎接近于零.总磷浓度与Chla浓度变化一致.蓝藻培养实验结果表明,20℃以下蓝藻不能大量生长繁殖.泥浆培养实验结果发现,太湖反硝化作用的最高温度阈值为25℃,在10~25℃之间反硝化潜力与温度呈现显著的线性关系（R²=0.99）.反硝化作用发生的最高硝态氮浓度阈值为4 mg ·L^-1,远高于太湖水体的硝态氮浓度,反硝化潜力最高达到（62.98±21.36）μmol ·（kg ·h）^-1.太湖水体反硝化速率受到硝态氮浓度的限制,而气候变暖导致湖泊温度提前升高,会使蓝藻提前生长,蓝藻生长对硝态氮的同化吸收会和反硝化作用产生竞争,使得大量氮还未被反硝化作用脱除就被藻类吸收利用,从而加剧蓝藻水华暴发的态势.研究结果对于解释近年来气候变化背景下太湖蓝藻水华反弹的机制具有重要科学意义.     

典型舰船用金属材料腐蚀与防护研究进展

针对舰船用金属材料在复杂海洋环境下存在的腐蚀问题,概述了舰船用金属材料腐蚀与防护的相关研究进展。介绍了合金钢、铜合金、钛合金和铝合金这些典型舰船用金属材料的常用类型和使用场所,阐述了舰船用金属材料所处不同海洋区带内的腐蚀环境特征,以及点蚀、缝隙腐蚀、电偶腐蚀、微生物腐蚀和应力腐蚀开裂等舰船用金属材料常发生的腐蚀类型。综述了目前对舰船用金属材料腐蚀防护采取的措施,重点关注了表面涂镀层和改性技术的研究进展。最后,提出了舰船用金属材料腐蚀防护未来的研究方向,需从加强腐蚀机理研究、建立腐蚀数据库和发展新型表面腐蚀防护技术3方面入手。     

生物质燃烧对东南亚及中国南方对流层臭氧含量影响的模拟研究

利用区域气候和大气化学模式系统,对2000年春季生物质燃烧排放影响东南亚及中国南部地区对流层臭氧含量进行模拟研究.结果表明,春季东南亚和南亚的生物质燃烧不仅影响源区对流层臭氧含量,而且对处于环流下游的中国南部地区也有显著作用;燃烧源区主要影响对流层低层,下游地区则影响对流层中低层.在源区引起的对流层臭氧总浓度增加达2.1×10^-1g/m²,对下游的中国南部地区增加量为9.0～12.0×10^-2g/m²;源区大气低层1000～900hPa的臭氧含量可增加36×10^-9m³/m³ 以上,而在中国南部750～700hPa高度上空的增加达15×10^-9m³/m³.     

水中五氯酚钠对发光细菌毒性测定的影响因素

应用发光细菌检测法,考察了不同的影响因素对水体中典型的有机污染物五氯酚钠的生物毒性测定结果的影响.结果表明,五氯酚钠对发光细菌的EC₅₀值随着pH值和硬度的增加而增加;五氯酚钠的15 min EC₅₀和20 min EC₅₀基本相符;与水体中相同浓度的常规有机污染物相比,五氯酚钠表现出更强的毒性,实验中常规有机污染物的存在对五氯酚钠毒性测定的结果影响较小.原水毒性检测实验显示一定毒性(相对发光率降低14%),原水水质对测定结果影响程度与去离子水相似.     

乙醛对脱氧核糖核酸分子的损伤作用

应用单细胞凝胶电泳技术和液相色谱-电化学检测法研究了典型环境污染物乙醛对脱氧核糖核酸(DNA)分子的损伤效应.结果表明:乙醛不仅可诱导人外周血淋巴细胞DNA发生链断裂,还可引起DNA-DNA,DNA-蛋白质交联;乙醛与小牛胸腺DNA的体外作用较弱,但在铁离子介导下对DNA的氧化能力增强,可产生一定量的8-羟基脱氧鸟苷(8-OHdG)加合物;动物实验表明,乙醛诱导大鼠肺组织DNA氧化损伤生成8-OHdG, 提示乙醛具有潜在遗传毒性,可能与引起DNA交联及氧化有关.     

混合堆肥过程中挥发性固体含量的层次效应及动态变化

城市污泥与猪粪混合堆肥表明:升温期和高温期堆体上部有机物降解的差异较大,降温期堆体下部各层有机物降解的差异较大,且堆体内挥发性固体(VS)含量已形成明显的层次效应,腐熟期堆体中部有机物降解的差异较大,堆体内VS含量的层次效应仍很明显;不同堆肥期堆体内VS含量的差异由大到小分别为:降温期≥腐熟期>高温期>升温期,不同部位有机物降解程度由大到小为:上部>中部>下部;VS含量随时间的变化满足一级反应动力学方程,城市污泥和猪粪混合堆肥过程中VS的降解速率约为0.3kg·d^-1,VS含量降低了8.2%.