电芬顿法处理重金属络合物Ni-EDTA的研究

本文首先研究了电絮凝与电芬顿对Ni-EDTA去除效率对比,结果发现电絮凝对Ni-EDTA去除效率较低.通过电化学阳极溶解产生Fe2+,外加H2O2反应的阳极电芬顿过程可有效去除Ni-EDTA.详细考察Ni-EDTA初始浓度、电流密度、p H值及H2O2投加量对Ni-EDTA去除率的影响.结果表明,电芬顿方法处理Ni-EDTA络合物其初始浓度越低,去除效果越好.反应最佳p H值为3.5,H2O2投加量在一定条件下存在最优值,而络合物的去除率随着电流密度的增加而提高.对Ni-EDTA去除过程进行了分析.     

特大城市集群绿色发展与生态足迹关联特征

本文以成渝城市群、长江中游城市群和长三角城市群为研究对象,解析不同空间尺度下绿色发展与生态足迹时空变化特征,并结合耦合协调度模型、环境库兹涅茨曲线（EKC）理论探究绿色发展与生态足迹的关联特征。研究表明,长江经济带城市群2000—2015年绿色发展水平逐年提升,约16.44%的城市达到较高水平,空间上呈现“东部高、西部低”的特征。人均三维生态足迹增长逐渐趋缓,成渝城市群达到峰值（5.21hm²）后逐年稳定下降。长江经济带绿色发展与生态足迹处于良好协调状态,绿色经济的快速发展带动了耦合协调度的提高。绿色发展与生态足迹存在倒“ U”形EKC曲线关系,由于自然资源基础和产业结构差异,成渝城市群（拐点出现在2008年）绿色发展与生态足迹协调关系好转早于中下游城市群（拐点分别在2019年、2012年）。四川、安徽应作为降低资源消耗的重点对象,未来应进一步加强区域中心城市的辐射带动作用,拉动周围城市提高绿色发展水平。研究成果能为区域绿色发展与生态环境协同管理提供思路与理论支持。     

我国推进环境污染责任保险的系统性风险及对策

环境污染责任保险是以企业发生的污染事故对第三者造成的损害依法应负的赔偿责任为标的的保险.本文在对我国环境污染责任保险30年发展历程进行全面回顾的基础上,从立法、模式、技术等层面出发,结合2019年底以来新型冠状病毒引发的公共卫生紧急事件挑战,分析了新时期政策实践面临的系统性风险,提出通过促进自上而下的立法推进与自下而上的自主试点良性互动、"低保额、低保障、广覆盖"的强制基本险与"高保额、高保障、个性化"的商业附加险灵活结合、经验数据积累与技术标准完善双管齐下、企业常态自主投保与特殊应急响应投保相互助力等方式妥善化解相关风险,为补齐生态短板、打好污染防治攻坚战、全面建成小康社会提供助力.     

基于APRIORI-TAN的交通事故伤害分析与预测*

为探究道路交通事故因素和事故伤害的相关性,以2 467起涉及人员伤亡的交通事故为数据集,运用Apriori算法分别挖掘事故伤害关联规则,并结合社会网络分析的可视化和核心-边缘分析构建受伤事故和死亡事故的关联规则网络。结果表明:事故伤害程度与事故时间、道路条件和交通环境等因素关系紧密,尤其死亡事故与碰撞固定物、人行横道事故、高速公路、高速道路、非市区、酒驾和超速存在高相关性。基于树型贝叶斯网络（TAN）构建事故伤害程度的预测模型,预测结果准确率可达87.56%。     

蒙特卡洛法计算750kV输电线路绕击跳闸率的研究

利用GDS多功能三轴仪,通过控制土样应变增量比开展了饱和砂土部分排水三轴试验;利用超静孔隙水压力、有效应力路径和应力应变关系三方面的实验结果,研究了饱和砂土的渐近状态特性。研究表明,控制应变增量比为常数进行常规三轴加载时,饱和砂土的有效应力比也趋于某一常数,形成渐近状态,且渐近状态应力比随应变增量比的增大而减小。基于土的剪胀特性给出了渐近状态形成的物理机制,并给出了北京某砂土在部分排水条件下渐近状态应力比的试验结果。     

The influence of slope collapse on water exchange between a pit lake and a heterogeneous aquifer

Slope collapse will reduce the water exchange. Slope collapse will affect the spatial distribution of the water exchange. Precipitation have the most impact on the dynamics of the water exchange. Due to the increase in open pit mining, pit lakes have become common surface water features, posing a potential risk to subsurface aquifer. In this study, a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package. For the first time, the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level. Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m³/a without collapse of the pit lake slope, while the total net water exchange under slope collapse conditions is 248000 m³/a (i.e., a reduction of 1.40-fold). The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April, shifting to negative values in zone IV from June to August and in zone V in June and July. Moreover, the monthly net water exchange per unit width decreases from north to south, and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse.     

Effect of solution pH on aging dynamics and surface structural evolution of mZVI particles: H<Subscript>2</Subscript> production and spectroscopic/microscopic evidence

A microscale zero-valent iron (mZVI)-based in situ reactive zone is a promising technology for contaminated groundwater remediation. Estimation of mZVI aging behavior after its injection into the subsurface is essential for efficiency and longevity assessments. In this study, batch tests were conducted to investigate the effect of initial pH on mZVI aging dynamics, as well as the formation and evolution of aging products over 112 days. Results indicated that mZVI aging accelerated with decreasing initial pH. Corrosion rates of mZVI particles under pH 6.0 and 7.5 were approximately two orders of magnitude higher than those observed at pH 9.0. The morphological, structural, and compositional evolution of mZVI particles in three systems (pH = 6.0, 7.5, and 9.0) were investigated using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In acidic and neutral solutions, a thick passivation layer with loosely and unevenly distributed aging precipitates was observed, and Fe₃O₄ was the final aging precipitate. Nevertheless, in alkaline solutions, minute aging precipitates were detected on the mZVI surface at 112 day. Characterization results suggested that mZVI was oxidized via the Fe⁰–Fe(OH)₂–Fe₃O₄ route. These findings shed new light on mZVI aging mechanisms, particularly its physicochemical characteristics and the structural evolution of mZVI in field-scale groundwater remediation applications.     

基于混凝土循环剥落的隧道火灾损伤数值模型研究

为研究混凝土高温剥落对隧道衬砌火灾损伤的影响,在现有隧道结构非线性瞬态热—力耦合有限元模型基础上,提出1种在火灾高温条件下混凝土发生剥落的循环算法,以模拟火灾下衬砌结构截面面积的损失,并引入混凝土临界剥落温度的概念,得出基于混凝土循环剥落的隧道衬砌火灾损伤数值模型建立流程。利用该模型对某隧道衬砌结构进行火灾损伤模拟,并与试验结果进行对比验证。结果表明:火灾下隧道混凝土衬砌结构内逐渐增大的热应力是导致普通混凝土高温剥落的主要原因;可将衬砌受火面是否达到临界剥落温度作为隧道发生高温剥落的充分条件进行火灾损伤分析;模型求解所得的数值模拟结果与现场火灾试验数据基本吻合,验证了其可行性;混凝土高温剥落与否对衬砌结构等效温度应力有较大影响,在隧道衬砌结构抗火性能分析过程中应尽量考虑混凝土高温剥落造成的影响。     

基于改进SIFT算法的交通事故图像匹配

为解决无人机航拍交通事故现场图像特征点数量较少、匹配成功率较低、耗时过长的问题,提出1种改进的SIFT算法,使用Gabor滤波对图像进行特征提取,基于改进的高斯金字塔和多方向多尺度Gabor频谱特点提取出具有尺度、旋转不变性的特征点,结合LLE算法对特征描述符进行降维处理,通过DBSCAN算法对特征点进行密度聚类,计算...     

Assessing the fractionation and bioavailability of heavy metals in soil–rice system and the associated health risk

Environmental Geochemistry and Health - This study developed a method to build relationships between chemical fractionations of heavy metals in soils and their accumulations in rice and estimate...