2015—2020年湖北省PM2.5和臭氧复合污染特征演变分析

为揭示湖北省PM_2.5和臭氧(O₃)复合污染演变特征,基于湖北省17个地市的空气质量国控点和武汉市大气超级站组分监测数据,全面分析湖北省17个地市2015—2020年PM_2.5和O₃的时空变化特征及相关关系,探讨PM_2.5和O₃协同效应的成因机理. 结果表明:①2015—2020年,湖北省PM_2.5显著改善,平均降幅为4.7 μg/(m3·a),但冬季负荷仍较高,主要集中于中部地区;O₃污染凸显,平均增幅为3.8 μg/(m3·a),污染集中在4—10月的暖季,东部地区最严重,近两年超标天数已与PM_2.5相当. ②湖北省PM_2.5和O₃关联日趋密切,协同效应显著,日评价指标显示夏季二者呈显著正相关(相关系数为0.57),近两年当PM_2.5浓度≤50 μg/m3时,相关系数高达0.63;冬季PM_2.5浓度与O_x(O₃+NO₂)浓度呈正相关,尤其2020年东部城市二者相关性高达0.46,显示大气氧化性对PM_2.5二次污染的重要性. ③以武汉市为例,归纳PM_2.5和O₃复合污染的成因,暖季低PM_2.5背景下,高温、中等湿度和弱风速的气象条件以及VOCs和NO_x等前体物的高浓度排放,使得受VOCs主控的光化学反应加剧,易造成O₃污染,从而加强PM_2.5二次生成;冬季高的大气氧化性,叠加不利气象条件,促进颗粒物的二次生成,导致重污染时PM_2.5组分以硝酸盐等二次无机组分为主. 研究显示,湖北省PM_2.5和O₃协同控制重点为,在保持现有NO_x控制力度基础上强化VOCs控制,遏制暖季和东部区域O₃浓度上升,加强冬季和中部PM_2.5治理.      

Daily Bank Erosion Rates in the Lower Yellow River Before and After Dam Construction

During the period of water impoundment and sediment detention of the Sanmenxia Reservoir, riverbank erosion processes played a key role in the channel evolution of the Lower Yellow River (LYR). However, research into bank erosion rates of the LYR has been neglected due to the lack of direct field monitoring. In this study, an indirect method is proposed to determine bank erosion rates at daily time scales by outlining a detailed calculation procedure using measured hydrological data. A total of 810 data points of daily bank erosion rates before and after the construction of Sanmenxia Dam was calculated at seven hydrometric sections along the LYR, with the corresponding values of the bank stability coefficient and the width‐to‐depth ratio also being calculated. Empirical relations were then developed to estimate the daily bank erosion rates, using these parameters at the sections. Temporal and spatial variability in daily bank erosion rates in the LYR before and after dam construction were also investigated, revealing that: (1) the bank erosion rates had a mean value of 16.7‐29.1 m/day in the braided reach, with a maximum value of 290.0 m/day, while they were relatively low in the meandering reach, with a mean value of 2.5 m/day; (2) the erosion rates before dam construction were slightly greater than those after dam construction, with the difference reaching 5‐10 m/day in the braided reach, decreasing in the transitional reach gradually, and being slight in the meandering reach.     

集成膜法水处理工艺的研究与应用

集成膜法除盐系统具有连续产水、出水质量好、易控制、占地少、不需酸碱、利于环保等优点。文章通过对集成膜法水处理技术进行研究与应用,将原有的化学除盐水处理方式改为集成膜法水处理工艺,该方法产水水质高且水质稳定,每年可节约酸碱200 t,阴、阳离子交换树脂10 t,切实解决电厂所面临的产水水质不稳定、酸碱废液排放等问题,有力推动了清洁生产。     

Genetic evidence of promiscuity in Peromyscus leucopus

Summary We collected pregnant female Peromyscus leucopus from natural populations during the summer of 1987 and 1988 and allowed these females to give birth to their field-conceived young in the laboratory. Blood samples were taken by suborbital puncture and phenotypes of five genetic loci (Esterase-1, trasferrin, hemoglobin, albumin and 6-phosphogluconate dehydrogenase) were studied using horizontal starch-gel electrophoresis to detect multiple paternity in single litters. Only esterase-1 was found to be highly polymorphic, with four alleles in samples of both years. One litter out of 29 in 1987 and 6 litters out of 32 in 1988 contained three different paternal alleles and served as direct evidence of multiple paternity in the field. The proportion of females engaging in multiple matings in natural populations of P. leucopus, assuming that all males were involved in every multiple mating, is 25%–100% (mean 68%). Because it is unlikely that all males are involved in every multiple mating, the actual proportion of females engaging in multiple matings should be greater. Offprint requests to: X. Xia at his Canadian address     

甲苯对土壤芳基硫酸酯酶活性的影响

甲苯作为土壤酶测定的前处理试剂及许多有机污染物在环境中降解的中间产物,有关其对土壤酶的影响研究在土壤酶学和环境科学领域具有重要意义.因此,采用模拟方法,较系统地研究了不同剂量甲苯和处理时间下芳基硫酸酯酶活性的变化规律.结果表明,甲苯对纯酶具有明显的抑制作用,酶活性降幅最大达到45.5%;灭菌土壤对溶液中的纯酶有很强的吸附能力;极微量的甲苯即可完成对土壤中酶活性的激活作用,酶活性增幅为109%～298%;随着甲苯剂量的增加,土壤酶活性的变化幅度逐渐趋缓,并可用Langmuir模型较好地拟合,由此获得了最大表观酶活性Umax,发现其与土壤性质显著相关,说明甲苯主要是通过杀死土壤中的微生物来影响土壤酶活性的.此外,初步探讨了不同土壤中胞外酶量与胞内酶量的关系,发现在供试土样中土壤芳香硫酸酯酶胞外酶和胞内酶分别占54.4%和45.6%.本研究可为后续土壤酶测定质量的完善和提高提供依据.     

厌氧序批式反应器预处理垃圾渗滤液的碳平衡研究

为初步了解垃圾渗滤液中有机物降解过程的物质和能量转化,对渗滤液实际处理工程提供借鉴,在最优工艺参数条件下,分别用处于中温(35±1)℃和常温状态的厌氧序批式反应器(ASBR)对垃圾渗滤液进行预处理。通过对反应器内的液相、气相和固相碳素进行全面的分析测定,结果表明:中温(常温)条件下,整个反应周期内约有86.4%(77.6%)的碳进入气相,约有1.7%(1.4%)的碳进入固相,其余约11.7%(22.3%)的碳仍存于液相中;其中,进入气相部分的碳有77.6%(71.3%)以甲烷形式存在,8.8%(4.7%)以二氧化碳形式存在,这说明ASBR预处理垃圾渗滤液过程中产生的甲烷资源化利用潜力较大。另外,反应器在中温状态下较常温状态处理效果更佳。     

电石渣-石膏湿法烟气脱硫废水处理工艺研究

电石渣-石膏湿法脱硫废水与石灰石-石膏湿法脱硫废水存在差异,主要体现在悬浮物与COD较难去除,采用在中和池添加助凝剂与曝气池添加氧化剂的方法,可在沿用石灰石法脱硫废水处理工艺设计的前提下达到对电石渣法脱硫废水的良好处理效果。     

基于高铁酸钾同步氧化-絮凝技术在污水处理中的研究进展

Fe(Ⅵ)具有较高的氧化还原电位,Fe(OH)3具有良好的絮凝效果,废水处理中高铁酸钾发挥同步氧化和絮凝作用。介绍高铁酸钾处理各种难降解废水的机理,同时分析高铁酸钾投加量、pH、反应温度、反应时间等因素对各种废水去除效果的影响。并提出基于高铁酸钾同步氧化絮凝技术处理污水的局限性和未来的发展方向。     

混合气体直接吸附分离回收过程研究

以精密陶瓷制造过程中排放的甲苯和异丙醇混合气体为目标气体,采用4段活性炭吸附柱串联吸附实验方式研究了混合组分气体直接吸附分离回收的可行性.结果表明,异丙醇和甲苯这2种物性具有一定差异的物质在吸附床的长度方向存在明显的分层吸附现象.在表观气速0.42 m·s-1、异丙醇与甲苯入口浓度分别为477 mg·m-3和746 mg·m-3、吸附柱总长为26cm条件下,通气吸附798 min时,0～10 cm长度段炭层吸附甲苯量为184.5 mg·g-1,吸附异丙醇量为0 mg·g-1,而21～26 cm长度段炭层吸附甲苯量为0.92 mg·g-1,吸附异丙醇量为91.2 mg·g-1,通过分段再生回收分别得到了纯度99%以上的甲苯和异丙醇回收液.弱吸附质异丙醇在吸附过程中存在气相浓度增浓现象,该现象导致实验条件下部分活性炭层区域对异丙醇的吸附量提高了27%以上.通过多段串联吸附、分段再生回收的方式可以实现混合气体的直接吸附分离回收.