大肠杆菌IscA膜表面表达菌株在吸附水体重金属中的应用

为构建一种能够高效、同时吸附水中多种重金属离子的大肠杆菌,利用融合蛋白表达技术,首先将大肠杆菌前脂蛋白信号肽Lpp、膜蛋白OmpA的N端部分氨基酸和铁硫簇组装蛋白IscA的编码基因序列进行融合,构建pET-Lpp-OmpA-IscA表达载体,将此载体导入大肠杆菌BL21菌株.在IPTG诱导下,IscA蛋白可表达于细胞膜表面.然后对IscA膜表面表达菌株对重金属的吸附能力进行评估,包括测定最大吸附容量、绘制吸附浓度依赖曲线和时间依赖曲线,以及对菌株清除工业污水中重金属的性能进行初步探索.研究结果表明,与本底对照菌株相比,IscA蛋白在细胞膜表面表达能够使菌株对水中的Cu~(2+)、Ni~(2+)、Cd~(2+)、Pb~(2+)、As~(3+)、Co~(2+)、Hg~(2+)这7种重金属的吸附能力提高2～5倍不等,并且在pH为6～8范围内保持其吸附能力基本不变.此菌株能够在30 min内将各种重金属溶液中超标5倍的金属含量降低至最大允许排放浓度以下,并且对吸附的重金属具有不同程度的回收能力和菌株再生能力.此外,该菌株能够同时吸附工业污水中的多种重金属,有效降低各种重金属含量.因此,利用膜表面表达技术对大肠杆菌进行改造,成功提高了大肠杆菌对多种重金属的吸附能力,为利用微生物治理环境重金属污染提供了良好的应用前景.     

Rational construction of Co-promoted 1T-MoS2 nanoflowers towards high-efficiency 4-nitrophenol reduction

Environmental Science and Pollution Research - Developing efficient and cost-effective non-noble metal catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is of great...     

季铵化改性对风化煤腐殖酸水处理性能的影响

对风化煤腐殖酸(HA)进行季铵化改性得到季铵化腐殖酸(QHA),将HA与QHA用作水处理剂,对比两者的阻垢缓蚀性能。结果表明,QHA的阻垢率和缓蚀率均优于HA。QHA、HA投加量分别在20、30 mg/L时阻垢率达到最大值,分别为85.77%、73.50%。HA与QHA的缓蚀率均随投加量的增大而提高,投加量为40mg/L时,QHA的缓蚀率达82.10%,比HA高出22.51百分点。QHA热稳定性能更好,阻垢缓蚀的最佳pH为8～9。QHA具有良好的分散能力和灭藻能力,可在8h内实现高效灭藻。CaCO3垢样的扫描电镜、X射线衍射分析表明,加入QHA使垢体松散,呈碎状分布,晶格结构发生畸变,CaCO3晶面生长的有序度和完整度下降,从而表现出良好的阻垢性能。     

Impact of environmental factors on gastric cancer: A review of the scientific evidence, human prevention and adaptation

Globally, gastric cancer (GC) ranks fifth in prevalence and third in fatalities, and shows a distinct geographical distribution in morbidity and mortality. Such a spatial pattern indicates that environmental factors could be an important contributor to GC. We reviewed a total of 135 relevant peer-reviewed articles and other literature published 1936–2019 to investigate the scientific evidence concerning the effects of environmental factors on GC worldwide. Environmental factors affect GC from the aspects of water, soil, air, radiation, and geology. Risk factors identified include water type, water pollution, water hardness, soil type, soil pollution, soil element content, climate change, air pollution, radiation, altitude, latitude, topography, and lithology; and most of them have an adverse impact on GC. Furthermore, we found that their effects followed five common rules: (1) the leading environmental factors that affect GC incidence and mortality vary by region, (2) the same environmental factors may have different effects on GC in different regions, (3) some different environmental factors have similar effects on GC in essence, (4) different environmental factors often interact to have combined or synergistic effects on GC, and (5) environmental factors can affect human factors to have an impact on GC. Environmental factors have a great impact on GC. Human beings may prevent GC by controlling carcinogenic factors, screening high-risk populations and providing symptomatic and rehabilitative treatments. Furthermore, adaptation measures are recommended to reduce GC risk on private and public levels. Future studies should transcend existing empirical studies to develop causal relationship models and focus on vulnerable population analysis.     

Environment and COVID-19 incidence: A critical review

The coronavirus disease 2019 (COVID-19) pandemic is an unprecedented worldwide health crisis. Many previous research studies have found and investigated its links with one or some natural or human environmental factors. However, a review on the relationship between COVID-19 incidence and both the natural and human environment is still lacking. This review summarizes the inter-correlation between COVID-19 incidence and environmental factors. Based on keyword searching, we reviewed 100 relevant peer-reviewed articles and other research literature published since January 2020. This review is focused on three main findings. One, we found that individual environmental factors have impacts on COVID-19 incidence, but with spatial heterogeneity and uncertainty. Two, environmental factors exert interactive effects on COVID-19 incidence. In particular, the interactions of natural factors can affect COVID-19 transmission in micro- and macro- ways by impacting SARS-CoV-2 survival, as well as human mobility and behaviors. Three, the impact of COVID-19 incidence on the environment lies in the fact that COVID-19-induced lockdowns caused air quality improvement, wildlife shifts and socio-economic depression. The additional value of this review is that we recommend future research perspectives and adaptation strategies regarding the interactions of the environment and COVID-19. Future research should be extended to cover both the effects of the environment on the COVID-19 pandemic and COVID-19-induced impacts on the environment. Future adaptation strategies should focus on sustainable environmental and public policy responses.     

交通空气污染对大鼠子代发育及社交行为的影响

交通空气污染与儿童自闭症的关联时有报道,但其因果关系仍待进一步探索。为研究出生前后暴露于不同水平的交通空气污染环境对生长发育和自闭症相关社交行为的影响,将Wistar大鼠雌雄1∶1交配,受孕雌鼠根据子代接触交通污染的时间(出生后暴露或胚胎期暴露)及浓度(低、中和高3个水平)分为6组。在子代出生后21～27 d,测量子代的体重、身长及大脑脏器系数,并根据三箱实验评估社交行为,同时检测仔鼠脑组织组蛋白H3第4个赖氨酸(H3K4)的甲基化水平。结果显示,出生前后,尤其是胚胎发育阶段接触较高浓度的交通空气污染物可导致幼鼠体重及大脑湿重较低,身长较短、大脑脏器系数偏高等生长发育特征改变。同时,出生前后较高浓度的交通空气污染物暴露可导致幼鼠出现社交能力下降、社交记忆受损及社交新颖性减弱等典型自闭症样行为改变。虽然组蛋白H3K4甲基化水平与交通空气污染物浓度之间未见统计学关联,但出生后暴露组具有较高的H3K4甲基化水平,提示出生前后接触交通空气污染物可能与自闭症的发生发展有关,而不同暴露时期对脑组织H3K4甲基化水平的影响,为今后进一步探讨自闭症的表观遗传机制提供了线索。     

典型工业城市中小学降尘重金属风险评估和源解析研究

典型工业城市存在着教育区和工业区交错分布的现象,周围企业产生的降尘将直接对学校儿童健康产生危害。本文以中原地区的典型工业城市—焦作市为研究对象,通过采集焦作市6所中小学校30个降尘样,开展重金属污染特征、健康风险评价和源解析研究。结果表明,采样学校降尘中重金属Zn、Cu、As、Pb、Cr、Ni的浓度均超过了相应的土壤背景值,尤其是Pb和Zn超标达6.31和5.66倍;各金属元素地累积指数值由大到小依次为Pb、Zn、Ni、Cu、As、Cr、Co和Mn,其中Co、Mn属于无污染,Cu、As、Cr属于无污染-中度污染,Zn、Ni属于中度污染,Pb属于中度污染-强污染;通过手-口摄入重金属的非致癌风险要高于其他两种摄入途径;总非致癌风险排序为Mn>Cr>As>Pb>Co>Ni>Cu>Zn,其中Mn、Cr、As的非致癌风险均大于1,对儿童存在非致癌健康风险;各采样学校的非致癌风险顺序为杨庄小学>人民中学>万方小学>光明中学>希望小学>塔南路小学;As、Ni、Cr、Co的致癌风险均不高于安全阈值,致癌风险均在可接受范围之内;PMF源解析显示该研究区域降尘中重金属的主要来源为燃煤工业排放(32.5%)>汽车排放(25.7%)>工业制造(25.2%)>道路和工业降尘(16.7%)。     

漂浮阴极SMFC传感器产电信号对不同重金属污染的响应特征及机制研究

我国十分重视对突发性水污染事件的监测和处置.本研究设计了一种实时在线监测重金属污染事件的漂浮阴极沉积物-微生物燃料电池传感器（漂浮阴极SMFC传感器）.该传感器阳极埋设在淹水土壤中,阴极漂浮在水面作为污染响应元件,并向阴极分别加入Zn²⁺、Cd²⁺、Co²⁺、Ni²⁺、Pb²⁺、Cu²⁺、Cr⁶⁺溶液以模拟水体重金属污染事件,以探究该传感器电信号对不同重金属污染的响应特征及机制.结果显示, Cu²⁺和Cr⁶⁺污染引起传感器出现明显的电压峰,而其他5种重金属污染则未引起明显的电信号响应.该传感器电压信号对Cu²⁺污染的最低检测限为5 mg·L^-1,灵敏度为1.06 mV·L·mg^-1,线性范围为5~40 mg·L^-1;Cr⁶⁺污染的最低检测限为40 mg·L^-1,灵敏度为0.17 mV·L·mg^-1,线性范围为40~200 mg·L^-1.X射线光电子能谱（XPS）表征分析显示,Cu²⁺和Cr⁶⁺污染的阴极表面分别存在单质Cu和Cr³⁺,表明Cu²⁺和Cr⁶⁺在阴极表面得电子还原,减弱了 阴极极化效应,引起电压上升.16S rRNA基因测序和定量结果显示,重金属污染前后土壤产电细菌相关属的数量无显著差异且产电细菌产生的基准电压较为平稳,优势产电细菌相关属均包含Bacillus和Clostridium.因此,漂浮阴极SMFC传感器适用于监测湿地水体Cu²⁺和Cr⁶⁺污染 事件,并且能够监测多次污染仍保持稳定运行.该监测技术能够快速发现水污染事件,有助于实现污染的快速处置.     

煤化工废水反渗透处理系统的运行效果及膜污染分析

针对煤化工废水反渗透（RO）膜处理系统夏季严重污堵的问题,本研究以实际某煤化工污水处理厂一级两段式RO系统为考察对象,分析了系统运行效能及膜污染特征.研究发现,生化段稳定地实现了有机物的削减,离子交换树脂进一步保障了产水的脱盐率,促进实现高水回收率,是煤化工废水零排放的重要保障.但对膜系统而言,脱盐及有机物去除的主要负荷集中在RO过程,一段/二段RO脱盐率分别为94.16%和96.16%,COD去除率分别为68.12%和87.4%;相对进水,一段RO有机物浓缩了9倍,二段RO盐浓缩了5倍.因此,两段膜过程都出现显著的膜污染,一段RO以有机-微生物-硅污染为主,形成致密的污染层,由进口到出口逐渐增厚,主要为蛋白质、多糖、腐殖酸;二段RO以Ca、Mg等的无机结垢为主,污染层结构相对松散,由进口到出口片状结晶逐渐增大.因此,预处理工艺的稳定运行及对污染物的去除以减轻RO过程的污染负荷是膜污染控制的关键;同时,针对RO系统中膜污染分布特征,制定杀菌、阻垢和化学清洗等膜污染控制策略以防止形成微生物抗性及"清洗剂抗性"具有重要意义.     

磁混凝预处理小城镇混合污水的效能与混凝机制研究

针对某小城镇污水处理厂混合进水浓度高的问题,本研究探讨了磁混凝技术在典型小城镇混合污水处理厂提质增效与技术升级改造中的适用性,结果表明,优化的混凝条件为：pH=7,PAC和PAM投加量分别为600 mg·L^-1和4 mg·L^-1,慢搅速率为30 r·min^-1.三维荧光光谱耦合区域面积积分法（FRI）和平行因子法（PARAFAC）的分析结果表明,污水中溶解性有机物（DOM）以色氨酸类、酪氨酸类及富里酸类3种组分为主,内源性特征明显.磁种可显著提升混凝效果,优化的磁种投加量为400 mg·L^-1,浊度和COD去除率分别为99.7%和82%.在磁混凝过程中,磁种作为絮体形成的核心并促进絮体生长,可显著提升絮体的比重、密实度与沉降性能,进而强化固液分离效率,沉降时间缩短为1/6.同时,密实度的增加和微磁场的作用可进一步提升絮体颗粒间的结合力,强化水力冲击下混凝过程的稳定性.因此,与传统混凝工艺相比,磁混凝 技术在典型小城镇污水处理提质增效中具有较高的应用潜能.