有机污染物在HDPE膜-膨润土复合防污帷幕中的一维扩散解析解

HDPE膜-膨润土复合防污帷幕被认为是目前最为安全有效的地下污染源阻隔技术之一.针对帷幕底部嵌入不透水层和帷幕下游地下水较为活跃的工况,推导了有机污染物在HDPE膜-膨润土复合防污帷幕三层结构中的一维扩散解析解.利用本文的解析解分析了HDPE膜-膨润土复合帷幕对亲水性和疏水性两类有机污染物的阻隔效果.分析结果表明:由于亲水性有机物与HDPE膜间的分配系数低,该复合防污帷幕对其阻隔效果显著优于具有高分配系数的疏水性有机物.对于疏水性有机物,可通过增大复合帷幕中膨润土的阻滞因子和帷幕厚度来改善其阻隔效果;膨润土的阻滞因子增大10倍且帷幕厚由0.6m增大为1.0m,改进后复合帷幕对疏水性有机物的阻隔效果可达到原帷幕对低分配系数亲水性有机物的阻隔水平.工程实践中可通过对HDPE膜进行表面处理以降低其分配系数或膨润土改性以增大其阻滞因子等措施来增强该复合帷幕的阻隔效果.     

城市大气污染分析及综合防治

城市大气污染已成为世界各国面临日益严重的环境问题,制约各国政治经济的快速发展,同时危害了人民群众的正常健康生活.如何防止城市大气污染,减轻其危害和影响,是当今重大而紧迫的课题.本课题系统分析了当前我国城市大气污染的状况、特点及成因,为有效防治大气污染提供了理论基础.     

地下水环境影响评价若干关键问题探讨

地下水环境影响评价一直是我国建设项目环境评价工作中较薄弱的一个环节,《环境影响评价技术导则——地下水环境》(HJ 610-2011)的实施对环境评价工作者提出了更高的要求.由于对水文地质条件的认识不够,众多环境评价工作者在评价工作中难以准确理解规范的要求,在确定主要评价对象、选择定量评价方法、采用科学的监测手段等方面陆续暴露出一些问题.本文结合《技术导则》的要求以及实际地下水环境影响评价工作的经验,从水文地质专业工作的角度,讨论了地下水环境影响评价水质和水量评价方面的若干关键问题,并就《技术导则》现状监测和影响预测中较难实现的若干技术问题提出了一些解决方案和修订建议,以供广大地下水环境评价工作者参考.     

典型连接件防腐密封剂在加速环境下的失效分析

针对某型飞机典型连接件的防腐蚀密封设计,采用实验室加速环境谱开展验证试验研究,结果表明含密封剂的防护体系在加速环境下发生了开裂失效。对密封剂的失效情况及原因进行了分析,提出了密封剂失效后的解决途径及相应的改进方案。     

Characterization, reactivity, source apportionment, and potential source areas of ambient volatile organic compounds in a typical tropical city

Based on one-year observation, the concentration, sources, and potential source areas of volatile organic compounds (VOCs) were comprehensively analyzed to investigate the pollution characteristics of ambient VOCs in Haikou, China. The results showed that the annual average concentration of total VOCs (TVOCs) was 11.4 ppbV, and the composition was dominated by alkanes (8.2 ppbV, 71.4%) and alkenes (1.3 ppbV, 20.5%). The diurnal variation in the concentration of dominant VOC species showed a distinct bimodal distribution with peaks in the morning and evening. The greatest contribution to ozone formation potential (OFP) was made by alkenes (51.6%), followed by alkanes (27.2%). The concentrations of VOCs and nitrogen dioxide (NO₂) in spring and summer were low, and it was difficult to generate high ozone (O₃) concentrations through photochemical reactions. The significant increase in O₃ concentrations in autumn and winter was mainly related to the transmission of pollutants from the northeast. Traffic sources (40.1%), industrial sources (19.4%), combustion sources (18.6%), solvent usage sources (15.5%) and plant sources (6.4%) were identified as major sources of VOCs through the positive matrix factorization (PMF) model. The southeastern coastal areas of China were identified as major potential source areas of VOCs through the potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models. Overall, the concentration of ambient VOCs in Haikou was strongly influenced by traffic sources and long-distance transport, and the control of VOCs emitted from vehicles should be strengthened to reduce the active species of ambient VOCs in Haikou, thereby reducing the generation of O₃.     

精密离心机静态半径测量不确定度的温度特性分析

目的研究温度对精密离心机静态半径测量不确定度的影响。方法以静态半径测量反算法为基础,推导静态半径测量不确定度的温度特性模型,设计精密恒温装置,并进行试验,获取加速度计在1 g离心机场下不同温度时的输出数据,并进行分析。结果基于温度特性模型,确定了影响静态半径测量不确定度的主要因素。试验数据结果表明,在加速度计工作范围内(50~60℃),静态半径测量不确定度随温度递增呈现“先增后减”的分布规律,且在50℃时进入到了10‒7量级。结论加速度计的温度敏感性是影响静态半径测量不确定度的最主要因素,精密控温能显著提高静态半径测量精度。     

气候变化对长三角臭氧污染影响的数值模拟研究

目的研究气候变化对污染物浓度的影响,进而了解其对环境空气质量的影响。方法利用WRF-Chem模拟2014年1月、7月(代表现在)和2050年1月、7月(未来)长三角地区的气象要素和空气质量的数据,研究气候变化对该区域臭氧浓度的影响。结果在夏季,未来(2050年7月)与现在相比(2014年7月),整个长三角区域的臭氧浓度变化幅度较小,约为-0.09×10~(-9),且呈现出北部增加,南部减少的趋势,在长三角北部的陆地地区,臭氧浓度增加达到极大值(15.0×10~(-9))。在冬季,与2014年1月的数据比较,未来(2050年1月)整个长三角地区臭氧比现在降低约7.9%,其中在上海以东洋面上减少达到极值(-25.1%)。结论在夏季,导致长三角北部地区臭氧浓度升高的主要原因是太阳辐射量的增加、VOC和NOx浓度的升高、边界层高度的降低以及增强南风的输送有关。长三角南部地区臭氧浓度的减少,主要原因是其太阳辐射的减少以及风速的增加。在冬季,在南通、上海以东洋面上臭氧减少的幅度较大,这与温度的降低、辐射的减少以及NOx浓度的增加有关。长三角南部区域的臭氧浓度有所增加,这与该区域太阳辐射的增加以及区域范围内的输送有关。在制定臭氧控制策略时,应该考虑未来气候变化的影响。     

安徽淮北临涣矿区地表水水化学及硫氢氧同位素组成特征

以淮北临涣矿区为研究对象,系统的采集了研究区河水、沉陷区积水和矿井排水等共23个水样,分析测试其常规水化学指标及氢氧硫同位素特征值。采用Piper三线图、Gibbs图与线性回归分析等方法,探讨了研究区不同类型地表水水化学组份特征及影响因素、SO_4~(2-)来源等问题。结果表明:研究区地表水TDS含量较高,属高矿化度水质类型,阳离子主要为Na~+和Ca~(2+),阴离子主要为HCO3-与SO_4~(2-),其中浍河河水水化学类型主要为Na~+-Ca~(2+)-HCO_3~-型,沉陷积水主要为Na~+-Cl~--SO_4~(2-)型;研究区河水和沉陷区积水SO_4~(2-)含量较高,平均值分别为412. 90 mg/L和490. 61 mg/L,河水中SO_4~(2-)主要来源于蒸发岩溶解、废水排放,沉陷区积水SO_4~(2-)来源于河水补给及矿井排水的影响;地表水的δD和δ~(18)O值变化范围为-55. 3‰～-29. 3‰和-7. 2‰～-2. 6‰,均落在大气降水线下方,表明其受到不同程度蒸发作用,河水、沉陷积水主要补给来源是大气降水; Gibbs图分析结果表明河水离子组成主要受岩石风化的控制,而沉陷区积水主要受蒸发作用影响。     

Preparation of porous semi-IPN temperature-sensitive hydrogel-supported nZVI and its application in the reduction of nitrophenol

Nanoscale zero-valent iron(n ZVI) particles supported on a porous, semi-interpenetrating(semi-IPN), temperature-sensitive composite hydrogel(PNIPAm-PHEMA). n ZVI@PNIPAmPHEMA, was successfully synthesized and characterized by FT-IR, SEM, EDS, XRD and the weighing method. The loading of nZVI was 0.1548 ± 0.0015 g/g and the particle size was30–100 nm. NZVI was uniformly dispersed on the pore walls inside the PNIPAm-PHEMA.Because of the well-dispersed n ZVI, the highly porous structure, and the synergistic effect of PNIPAm-PHEMA, nZVI@PNIPAm-PHEMA showed excellent reductive activity and wide p H applicability. 95% of 4-NP in 100 m L of 400 mg/L 4-NP solution with initial p H 3.0–9.0 could be completely reduced into 4-AP by about 0.0548 g of fresh supported n ZVI at 18–25 °C under stirring(110 r/min) within 45 min reaction time. A greater than 99% 4-NP degradation ratio was obtained when the initial p H was 5.0–9.0. The reduction of 4-NP by nZVI@PNIPAm-PHEMA was in agreement with the pseudo-first-order kinetics model with Kobsvalues of 0.0885–0.101 min-1.NZVI@PNIPAm-PHEMA was able to be recycled, and about 85% degradation ratio of 4-NP was obtained after its sixth reuse cycle. According to the temperature sensitivity of PNIPAmPHEMA, n ZVI@PNIPAm-PHEMA exhibited very good storage stability, and about 88.9%degradation ratio of 4-NP was obtained after its storage for 30 days. The hybrid reducer was highly efficient for the reduction of 2-NP, 3-NP, 2-chloro-4-nitrophenol and 2-chloro-4-nitrophenol. Our results suggest that PNIPAm-PHEMA could be a good potential carrier, with n ZVI@PNIPAm-PHEMA having potential value in the application of reductive degradation of nitrophenol pollutants.     

活性炭纤维负载柠檬酸铁活化过硫酸氢钾降解罗丹明B的研究

以ACF（活性炭纤维）为载体,制备出一种新的非均相催化剂ACF@Cit-Fe/S〔将Cit-Fe（柠檬酸铁）负载在ACF表面并引入S元素〕,并采用SEM-EDS（电镜-能谱）、XPS（X射线光电子能谱）对其进行表征,研究其活化PMS（过硫酸氢钾）降解染料RhB（罗丹明B）的降解效果.结果表明:①ACF表面成功负载了Cit-Fe和S元素,Cit-Fe和S元素的掺杂增强了ACF催化PMS的性能,能有效降解染料RhB,反应120 min时RhB的脱色率达98%.②ρ（ACF@Cit-Fe/S）、c（PMS）对RhB降解有一定的影响,ρ（ACF@Cit-Fe/S）为0.5 g/L、c（PMS）为6 mmol/L是降解RhB（10 mg/L）的最佳投加量.③温度对RhB降解速率的影响符合阿伦尼乌斯模型,通过计算得出活化能为39.47 kJ/mol,降解过程是一个表面反应控制过程.④以叔丁醇、甲醇、苯酚为分子探针的自由基清除试验显示,SO₄-·（硫酸根自由基）和HO·（羟基自由基）是降解反应过程中主要的自由基,其主要存在于催化剂表面及其周围.研究显示,ACF@Cit-Fe/S能用于活化PMS的高级氧化体系中,ACF@Cit-Fe/S表面丰富的电子转移过程导致其活化PMS的能力增强,从而促进SO₄-·和HO·的产生,提高RhB的降解效率.