铜氰溶液的电子束辐照降解

研究了铜氰溶液中总氰初始浓度、pH、铜浓度等对总氰降解效率的影响,比较了KCN溶液和铜氰溶液的总氰降解率,初步推断了铜氰溶液在辐照过程中的降解机制.实验结果表明,在同样的辐照剂量下,随着总氰初始浓度的增加,总氰降解率降低,相应的总氰降解G值增大;铜浓度越低,总氰降解率越高;pH越小的铜氰溶液总氰降解率越高.电子束辐照KCN溶液和铜氰溶液的总氰降解反应属于表观一级反应.在相同的辐照剂量下,KCN溶液的总氰降解率比铜氰溶液要高得多.铜氰溶液的电子束辐照降解过程非常复杂,主要是铜氰络合离子逐步离解出的CN-与·OH的反应.     

Kinetics and pathways for the debromination of polybrominated diphenyl ethers by bimetallic and nanoscale zerovalent iron: effects of particle properties and catalyst

Polybrominated diphenyl ethers (PBDEs) are recognized as a new class of widely-distributed and persistent contaminants for which effective treatment and remediation technologies are needed. In this study, two kinds of commercially available nanoscale Fe⁰ slurries (Nanofer N25 and N25S), a freeze-dried laboratory-synthesized Fe⁰ nanoparticle (nZVI), and their palladized forms were used to investigate the effect of particle properties and catalyst on PBDE debromination kinetics and pathways. Nanofers and their palladized forms were found to debrominate PBDEs effectively. The laboratory-synthesized Fe⁰ nanoparticles also debrominated PBDEs, but were slower due to deactivation by the freeze-drying and stabilization processes in the laboratory synthesis. An organic modifier, polyacrylic acid (PAA), bound on N25S slowed PBDE debromination by a factor of three to four compared to N25. The activity of palladized nZVI (nZVI/Pd) was optimized at 0.3 Pd/Fe wt% in our system. N25 could debrominate selected environmentally-abundant PBDEs, including BDE 209, 183, 153, 99, and 47, to end products di-BDEs, mono-BDEs and diphenyl ether (DE) in one week, while nZVI/Pd (0.3 Pd/Fe wt%) mainly resulted in DE as a final product. Step-wise major PBDE debromination pathways by unamended and palladized Fe⁰ are described and compared. Surface precursor complex formation is an important limiting factor for palladized Fe⁰ reduction as demonstrated by PBDE pathways where steric hindrance and rapid sequential debromination of adjacent bromines play an important role.     

A meta-analysis of heavy metals pollution in farmland and urban soils in China over the past 20 years

A total of 713 research papers about field monitor experiments of heavy metals in farmland and urban soils in China, published from 2000 to 2019, were obtained. A meta-analysis was conducted to evaluate the level of China's heavy metal pollution in soils, mainly focusing on eight heavy metals. It was found that the average concentrations of cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), mercury (Hg), chromium (Cr), nickel (Ni), and arsenic (As) in China were 0.19, 30.74, 85.86, 25.81, 0.074, 67.37, 27.77 and 8.89 mg/kg, respectively. Compared with the background value (0.097 mg/kg), the Cd content showed a twofold (0.19 mg/kg) rise in farmland soils and a threefold (0.29 mg/kg) rise in urban soils. The decreasing order of the mean I_geo was Cd (1.77) > Pb (0.62) > Zn (0.60) > Cu (0.58) > Hg (0.57) > Cr (0.54) > Ni (0.47) > As (0.28). Nearly 33.54% and 44.65% of sites in farmland and urban soils were polluted with Cd. The average concentrations of eight heavy metals were not sensitive change in recent two decades in farmland and urban soils. The average P_n values for urban (2.52) and farmland (2.15) soils showed that heavy metal pollution in urban soils was more serious than that in farmland, and the middle Yangtze River regions, where industrial activity dominates, were the most polluted. The meta-analysis comprehensively evaluated the current pollution situation of soil heavy metal, and provided important basis for soil management and environment prevention in China.     

可溶性有机质对芘在泥炭和高岭土上吸附和解吸的影响

为掌握可溶性有机质(DOM)对憎水性有机污染物吸附和解吸行为的影响,本研究选取四环多环芳烃——芘作为目标污染物,通过批平衡实验研究了不同分子量组分DOM对芘在泥炭和高岭土上吸附和解吸的影响.结果表明,吸附和解吸数据均可以用Freundlich模型很好地拟合(R2＞0.93).DOM的添加抑制了泥炭对芘的吸附,并且分子量...     

埕岛油田浅海石油钻井平台拖航移位隐患分析

胜利作业三号平台是中石化胜利油田分公司钻井工艺研究院和上海交通大学联合设计,青岛北海船厂建造,隶属井下作业公司使用的第一座齿轮齿条升降的自升式浅海钻井平台,该平台钢质非自航,由平台主体、桩腿和桩靴、升降系统3部分组成.平台主体平面形状接近三角形,3根圆柱形桩腿布置在艏、艉,桩靴为正方形.平台主要任务是对水深5～25 m范围内的油井进行修井作业,适用于4 500 m深度井筒.文章对浅海钻井平台拖航中存在的风险进行了分析,提出了应对措施.     

好氧颗粒污泥处理高含盐废水研究

试验采用序批式摇床反应器(SSBR)在高含盐废水中利用不同类型接种污泥培养出了好氧颗粒.结果表明,好氧颗粒污泥能够有效处理高含盐废水并且具有很好的抗盐度冲击能力.当废水盐度小于10 g/L NaCl并且进水基质为葡萄糖时,利用好氧颗粒污泥处理该废水可以取得70.3%～97.6%的TOC去除率.当进水盐度达到35 g/L NaCl并且进水基质为难降解Vc废水时,利用好氧颗粒污泥处理该含盐废水能够取得与相同基质相同运行条件下淡水废水中相似的70%的TOC去除率.试验在含盐废水中得到了粒径为0.5～3 mm的好氧颗粒污泥,其沉降速度大大高于淡水对照组中得到的好氧颗粒污泥沉降速度.相对淡水对照组中好氧颗粒污泥,含盐废水中好氧颗粒具有污泥产率更低、污泥活性(OUR)更高、颗粒稳定性更好的优势.从不同接种污泥类型来看,好氧絮状污泥和厌氧颗粒污泥接种都能快速实现污泥好氧颗粒化,但絮状污泥接种实现好氧颗粒化所需的时间更短.另外,在相同运行条件下,接种好氧絮状污泥反应器取得的TOC去除效果优于接种厌氧颗粒污泥反应器,但厌氧颗粒污泥接种具有更强的抗盐度冲击能力.     

O3/H2O2降解Atrazine效能研究

利用O3/H2O2降解莠去津,对氧化产物进行了色谱分析,以评价该体系降解莠去津效能.莠去津初始浓度2 mg/L,7.5mg/L的O3单独氧化去除率为27.2%;相同O3投量下,H2O2/O3摩尔比0.75时,5 min莠去津的去除率最高可达96.5%,表明H2O2/O3体系对莠去津的去除效果良好,降解速度快.以离子色谱对产物的离子进行分析,莠去津浓度下降的同时,硝酸根和氯离子浓度增高.GC-MS检测的产物和对LC-MS谱图的分析表明,有机产物中存在脱乙基、脱异丙基和脱氯莠去津,说明H2O2/O3并不能彻底氧化莠去津,因此工程中作为主要去除单元或突发性污染事件的应急手段可能还需要与活性炭等单元联用.     

多种工况下尾矿坝稳定性分析

尾矿坝的稳定性是评价一座尾矿库安全的重要指标,然而尾矿坝的坝高、坡比以及尾矿渣的不同状态是影响尾矿坝稳定性的重要影响因素。在分析尾矿坝稳定性影响因素的基础上,通过FLAC3D软件内嵌的强度折减法计算分析了同种条件下某尾矿坝的坝高、坡比对尾矿坝稳定性的影响,计算并对比了尾矿渣在自然和饱水状态下尾矿坝的安全系数。结果表明:在相同坝高下,坡比对稳定性影响较大,而在相同坡比下,坝高对稳定性影响相对较小;饱水状态下的尾矿渣更容易使尾矿坝体发生破坏。     

2008年南方低温冰雪灾害对农业的影响及对策

结合参加农业部组织的分省灾害评估调查活动,分析了2008年南方低温冰雪灾害的成因,指出是一系列天文、地球物理和大气环流异常因素构成的复杂灾害链所诱发。论述了低温冰雪灾害对南方农业生产的影响,总结了抗灾和补救的对策与措施。反思灾害中的经验教训,提出应健全预警机制和建立救灾物资储备,加强减灾和应急救援的技术储备,积极探索适合国情的农业灾害保险制度,通过提高公众素质和健全法制实现调动全社会的力量减灾。     

基于鱼类完整性指数的滦河流域生态系统健康评价

生物完整性指数作为评价河流健康的重要工具,对流域管理有明确的指导作用.为全面掌握滦河流域生态系统健康状况,构建F-IBI（鱼类完整性指数）,开展滦河流域生态系统健康评价.于2016年10-11月对滦河流域58个采样点收集了鱼类与环境数据,根据栖息地质量评分与水质等级来确定参考点（12个）和受损点（7个）.利用分布范围检验、敏感性分析及冗余检验对20个候选指标进行筛选,以获得构建F-IBI的核心指标.采用1、3、5赋分法对核心指标进行赋分,并计算F-IBI最终得分.利用分位数法将F-IBI划分为"健康" "亚健康" "一般" "差" "极差"5个等级.利用非参数检验对F-IBI的适用性进行校验.结果表明:①鱼类物种数、个体数、Shannon-Wiener多样性指数、底栖食性鱼类个体百分比、耐受性鱼类个体百分比、产黏性卵鱼类个体百分比、产沉性卵鱼类个体百分比、上层鱼类个体百分比和广布种鱼类个体百分比等9个指标被筛选出,其适合作为构建F-IBI的核心指标.②F-IBI计算结果表明滦河流域58个采样点中,"健康"和"亚健康"等级采样点有22个,"一般"等级采样点22个,"差"和"极差"等级采样点14个.滦河干支流上游地区健康状况较好,干流中下游及部分独流入海河流健康状况较差,这主要受到不同地区社会经济发展的影响.③Mann-Whitney U检验发现,F-IBI在参考点与非参考点之间有显著差异,栖息地综合得分随F-IBI评价等级降低而下降,在"健康"与除"亚健康"外的其他等级以及"极差"与除"差"外的其他等级之间有显著差异.研究显示,构建的F-IBI适用于滦河流域生态系统健康评价.