Correlating metal ionic characteristics with biosorption capacity using QSAR model

The relationship between metal ionic characteristics and the maximum biosorption capacity (q(max)) was established using QSAR model based on the classification of metal ions (soft, hard and borderline ions). Ten kinds of metal ions (Ag(+), Cs(+), Zn(2+), Pb(2+), N(i2+), Cu(2+), Co(2+), Sr(2+), Cd(2+), Cr(3+)) were selected and the waste biomass of Saccharomyces cerevisiae obtained from a local brewery was used as biosorbent. Eighteen parameters of physiochemical characteristics of metal ions were selected and correlated with q(max). Classification of metal ions could improve the QSAR models and different characteristics were significant in correlating with q(max), such as polarizing power Z(2)/r or the first hydrolysis constant |logK(OH)| or ionization potential IP. X(m)(2)r seemed to be suitable for metal ions including soft ions, and Z(2)/r, |logK(OH)| and IP suitable for only soft ions or metal ions excluding soft ions. It provided a new way to predict the biosorptive capacity of metal ions.     

Seasonal variation of monomethylmercury concentrations in surface sediments of the Tagus Estuary (Portugal)

Surface sediments (0-2cm) were collected at 40 sites along the Tagus Estuary in July and December 2004. The sediments were analysed for total mercury, monomethylmercury (MMHg) and interpretative parameters (e.g. redox potential, pH, C(org)). No significant differences in total Hg, pH, Al, Fe, Mn and C(org) were found between sediments collected in the two periods, but MMHg concentrations were higher in July. On average sediments were warmer and more reducing in summer. On the basis of these results, an increase of 7kg of MMHg (+37%) in surface sediments of the Tagus Estuary was estimated. Presumably higher temperatures in summer promote the increase of microbial activity and higher methylation rates. The alterations observed in this study point to the potential importance of seasonal changes in MMHg production at surface sediments with eventual changes in the MMHg uptake by benthic invertebrates and other organisms in the food web.     

面向非均衡文本信息的企业生产安全氛围智能感知模型

现有企业生产安全氛围的主要描述载体是文本,但文本无法定量描述的特点是企业生产安全氛围分析面临的重要挑战。基于机器学习和自然语言处理技术处理企业生产安全氛围文本信息,着重从安全氛围主题辨识和安全氛围等级预测两方面,综合实现对企业生产安全氛围的智能感知。首先借鉴合成少数类过采样技术(SMOTE)算法思想,提出一种“类SMOTE”算法,用于解决非均衡文本数据问题;然后基于隐含狄利克雷分布(LDA主题模型)实现安全氛围主题辨识,得到文本主题词及相关权重;最后基于机器学习算法实现安全氛围等级预测。经过实例验证,提出的“类SMOTE+LDA+Bayes”组合模型,对于企业生产安全氛围智能感知效果较好。     

基于色差分析的复合绝缘子伞裙老化程度表征研究

高温硫化硅橡胶具有良好的憎水性、憎水迁移性,有效提高了复合绝缘子的耐污闪性能。但是作为一种有机高分子材料,高温硫化硅橡胶材料在长期运行之后会表现出一定的老化特征,包括出现粉化、褪色、龟裂等现象。作为复合绝缘子最直观的特征,伞裙护套的颜色变化可以在一定程度上反映出硅橡胶材料的性能变化。对复合绝缘子伞裙的颜色变化特征进行了研究,并利用RGB颜色空间对其进行了定量表征,试验结果表明,利用复合绝缘子伞裙颜色变化特征对其老化状态进行表征是可行的。     

石化废水生化处理前后抗雌激素活性的变化

以某企业的石化废水处理工艺为对象,利用固相萃取-双杂交酵母法,对混入和未混入苯胺废水2种典型工况下进、出水的抗雌激素活性进行了研究,以了解不同性质废水的混合处理对石化废水抗雌激素活性的影响规律. 结果表明,现有的废水处理系统能有效降低有机物浓度,2种典型工况下溶解性有机碳(DOC)的去除率分别可达72%和74%,但生成了更具抗雌激素活性的物质. 在混入苯胺废水的工况下,出水的抗雌激素活性显著高于进水,为进水的2.8倍. 进一步研究废水中不同组分的抗雌激素活性发现,苯胺废水中的疏水性物质是导致出水抗雌激素活性升高的主要原因.      

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the RO_x (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%–150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%–50% enhancements in the areas around 35–40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.     

支化聚乙烯亚胺功能化磁性纳米吸附剂的制备及对Cu2+的吸附研究

为解决水体中重金属Cu²⁺污染,本研究首先采用水热法制备得到超顺磁四氧化三铁纳米粒子,然后使用对Cu²⁺具有强络合作用的含有丰富氨基官能团的支化聚乙烯亚胺接枝到纳米粒子表面,得到Fe₃O₄@BPEI磁性纳米吸附剂。采用红外光谱(FTIR)、X射线粉末衍射(XRD)、透射电子显微镜(TEM)等对其结构、尺寸及形貌进行表征。研究了不同吸附因素对吸附剂吸附Cu²⁺的影响,确定了最佳吸附条件,并通过吸附动力学模型和吸附等温线模型进一步探讨吸附机理。结果表明：支化聚乙烯亚胺成功接枝到四氧化三铁纳米粒子表面。最佳吸附条件为pH=6.0、吸附平衡时间为40 min、吸附剂用量为10 mg。通过实验数据拟合,Fe₃O₄@PEI吸附Cu²⁺的过程符合Langmuir等温吸附方程和拟二级动力学模型,表明吸附过程为化学吸附控制的单分子层覆盖,在303 K时,模型理论饱和吸附量为141.24 mg/g。表明支化聚乙烯亚胺修饰的磁性纳米吸...     

西安供暖前后细颗粒物化学特征及棕碳吸光特性

2015年11月1—30日在西安用大流量采样器每12 h进行1次细颗粒物(PM_(2.5))样品采集,分析供暖前后PM_(2.5)中有机碳(OC),元素碳(EC),水溶性有机碳(WSOC)与无机离子的浓度和棕碳吸光度的变化特征,探讨供暖对城市大气气溶胶理化特性的影响。结果显示:供暖前(11月1—15日)与供暖后(11月16—30日)PM_(2.5)浓度分别为127±59μg?m~(-3)和164±126μg?m~(-3),供暖后比供暖前增加了30%,其中K~+、Cl~-、和分别增加了30%、70%、40%和38%。洁净期(PM_(2.5)75μg?m~(-3))与灰霾期(PM_(2.5)150μg?m~(-3))对比显示:洁净期Na~+、Ca~(2+)、Mg~(2+)的相对含量均大于灰霾期,这是由于灰霾发生时不利的静稳天气条件(风速1 m?s~(-1))使得粉尘粒子干沉降效应增加所致。洁净期[NO_3~-]/[SO_4~(2-)]质量比均大于1而灰霾期均小于1,这是因为灰霾期高湿条件有利于二氧化硫液相转化为硫酸盐所致。供暖前灰霾期[NO_3~-]/[SO_4~(2-)]比值要高于供暖后的灰霾期,这与西安及其周边地区燃煤取暖排放二氧化硫增加有关。供暖前后棕碳的质量吸收效率(MAE)值均是洁净期大于灰霾期,表明:与非灰霾天相比,当灰霾发生时不利的静稳天气条件使得细粒子在大气中长时间存留,延长其二次氧化反应时间,使得棕碳中含C=C不饱和键的吸光性物质被深度氧化,从而降低其吸光性能。     

基于层次分析法的洞庭湖生态安全评估

采用"驱动力-压力-状态-影响-风险"模型,选取14项指标,构建洞庭湖生态安全评价指标体系.利用层次分析法确定各指标的权重,运用生态安全度计算模型,对2000,2005,2007年洞庭湖生态安全状况进行分级评价.结果表明,与20世纪80年代相比,2000年洞庭湖区评价级别处于安全状态;2007年处于一般状态,生态安全状态水平下降,状态得分值仅为基准年的57.2%.对状态做进一步分析可知,TP和Chl.a是造成洞庭湖水生态状况恶化的主要原因.