锌冶炼区耕地土壤和农作物重金属污染状况及风险评价

对贵州省某典型锌冶炼区耕地土壤和主要谷类农作物(稻米、玉米和小麦)进行取样调查,测定了土壤和谷类农作物中重金属Pb、Cd、Zn和Cu的含量,采用单因子污染指数和综合污染指数法评价了土壤和作物籽粒中重金属的污染状况,并分别采用潜在生态风险指数(RI)和危险商(HQ)法评价了土壤重金属污染的潜在生态风险程度和作物中重金属对成人和儿童的健康风险.结果表明:(1)冶炼区耕地土壤受到了重金属不同程度的污染,污染程度排序:玉米地水稻田小麦地,且CdCuZnPb,内梅罗综合污染指数分析结果表明,玉米地污染程度为重污染,水稻田和小麦地为轻污染,且均以Cd对综合指数的贡献最大;(2)土壤Cd存在极强生态风险,4种重金属潜在生态危害大小顺序为:CdPbCuZn;生态风险指数(RI)研究结果表明,研究区处于轻微、中等、强的和很强的生态风险程度的采样点比例分别为1.41%、21.1%、35.2%和42.3%.(3)冶炼区农作物稻米中重金属Pb、Cd、Zn、Cu的平均含量分别为0.145、0.017、16.97和2.704 mg·kg~(-1);玉米中重金属Pb、Cd、Zn、Cu的平均含量分别为0.094、0.055、26.81和4.464 mg·kg~(-1);小麦中重金属Pb、Cd、Zn、Cu的平均含量分别为0.048、0.085、35.37和5.426 mg·kg~(-1).(4)研究区稻米、玉米和小麦均存在重金属超标现象,重金属污染程度为小麦最重,稻米和玉米的污染程度相当,稻米和玉米污染等级均为安全,小麦处于警戒线.(5)各重金属元素每日摄入量均低于美国环保署的参考暴露剂量,安全性较好,但食用该区域谷类农作物引起复合重金属污染对成人和儿童均存在健康风险.(6)耕地土壤重金属含量与谷类农作物可食部分重金属含量间无明显相关性.     

正常污泥和膨胀污泥中EPS膜污染特性及其与膜表面作用能分析

胞外聚合物(Extracellular polymeric substance,EPS)是导致膜污染的重要物质,且不同形态污泥的EPS具有不同的性质,研究正常污泥和膨胀污泥的EPS膜污染特性具有重要意义.因此,实验考察了正常污泥和膨胀污泥的膜污染速率.结果表明,膨胀污泥膜污染速率远高于正常污泥,膨胀污泥EPS(Bulking sludge-EPS,BS-EPS)浓度((172.9±10.4) mg·g-1)明显高于正常污泥EPS(Normal sludge-EPS,NS-EPS)浓度((95.9±6 6) mg·g-1),且膨胀污泥的蛋白质/多糖(Protein/Carbohydrate,P/C)值(2.26)高于正常污泥的P/C值(1 97)此外,通过序批式吸附实验研究了正常污泥和膨胀污泥的EPS膜污染差异,并基于Derjaguine-Landaue-Verweye-Overbeek (XDLVO)理论计算了EPS与PVDF膜表面之间的作用能结果表明,EPS-膜系统的总界面能为负值,即EPS-膜系统之间会发生自吸附行为,而膜与BS-EPS的总界面能(-63.943mJ.m2)较膜与NS-EPS(-56.366 mJ·m2)具有较高的能量,因此,BS-EPS与膜的吸附力较强;NS-EPS和BS-EPS主要能量壁垒分别为8.89 kT和7.51 kT,表明NS-EPS与膜之间的排斥力更强,因而BS-EPS更容易造成膜污染     

海河流域重污染河流表层沉积物氨基酸组成特征

为探明子牙河水系沉积物氮的主要形态,采用柱前衍生反相高效液相色谱-同位素内标法研究了表层沉积物中20种氨基酸的形态及组成特征.结果表明:子牙河水系沉积物中有机氮是氮的主要存在形态,沉积物有机氮(SON)平均浓度为3114 mg·kg^-1,总水解氨基酸氮(THAAs-N)占SON的45.53%;蛋白类氨基酸氮是THAAs-N的主体,占THAAs-N的90.24%,为沉积物潜在释放氮及矿化氮的主体;子牙河水系表层沉积物氨基酸以甘氨酸(Gly)、脯氨酸(Pro)摩尔含量最高,分别占THAAs的14.70%、10.00 %;根据官能团类型分类,蛋白类氨基酸为主要类别,占THAAs的89.50%;蛋白类氨基酸以中性氨基酸为主,平均含量为THAAs的40.69%;亚氨基酸及非蛋白类氨基酸的含量差异性从侧面反映出水系河流污染物来源;采用Glu/γ-Aba及DI指数判断有机质的降解程度,结果显示子牙河水系大部分区域沉积物有机质降解程度较低.     

Adsorption of lead on multi-walled carbon nanotubes with different outer diameters and oxygen contents: Kinetics, isotherms and thermodynamics

The effects of different outer diameters and surface oxygen contents on the adsorption of heavy metals onto six types of multi-walled carbon nanotubes (MWCNTs) were investigated in an aqueous solution and lead was chosen as a model metal ion. The results indicated that the percentage removal and adsorption capacity of lead remarkably increased with decreasing outer diameter due to larger specific surface area (SSA). The SSA-normalized maximum adsorption capacity (qm /SSA) and SSA-normalized adsorption coefficient (Kd /SSA) were strongly positively correlated with surface oxygen content, implying that lead adsorption onto MWCNTs significantly increases with the rise of oxygen content and decreases with decreasing SSA. The calculated thermodynamic parameters indicated that adsorption of lead on MWCNTs was endothermic and spontaneous. When the oxygen content of MWCNTs increased from 2.0% to 5.9%, the standard free energy (△ G0 ) became more negative, which implied that the oxygenated functional groups increased the adsorption affinity of MWCNTs for lead. Through calculation of enthalpy (△ H0 ), G0 and free energy of adsorption (Ea ), lead adsorption onto MWCNTs was recognized as a chemisorption process. The chemical interaction between lead and the phenolic groups of MWCNTs could be one of the main adsorption mechanisms due to highly positive correlations between the phenolic groups and K d /SSA or q m /SSA.     

适用于中国燃煤电厂的汞监测及排放控制技术

随着GB 13223—2011《火电厂大气污染物排放标准》的颁布,汞排放问题正式列入了控制目标,这必将对燃煤电厂的环保设施提出新的更高的要求。在综述国外汞监测技术的前提下,总结脱硫脱硝污染物监测的经验,针对中国的具体情况分析了新形势下我国燃煤电厂汞监测技术的发展方向和关键技术的开发重点。同时分析了在最大化地利用燃煤电厂现有环保设施和设备的情况下,如何开发在今后一段时期内最适宜在我国广泛应用的汞排放控制技术,也对国内今后的政策发展进行了预测。     

物元分析模型在生活垃圾分类收集方案评价中的应用

家庭生活垃圾分类收集是实现城市生活垃圾无害化、减量化和资源化的重要方面,而生活垃圾分类收集方案评价也是实现生活垃圾综合管理的有效方法。以昆明市居民区生活垃圾分类收集为例,设计5种垃圾分类收集方案,基于问卷调查和层次分析,并建立物元分析模型,得出最优分类方案是将生活垃圾分为厨余垃圾与其他垃圾2大类。     

餐厨垃圾与污水污泥共消化产酸试验研究

研究了餐厨垃圾与污水污泥在不同混合比例、不同污泥停留时间条件下的共消化产酸效果。试验结果表明:当餐厨垃圾与污水污泥TS比为1∶3时,SRT=1 d的反应器酸化效率最高,且乙酸含量占优,产酸效果较佳;当TS之比为1∶1时,各反应器产酸量普遍高于1∶3时,其中SRT=5 d产酸反应器,最高酸化效率达5.94,产酸量最大,且乙酸含量占优,运行效果最佳。     

Enhanced photocatalytic activity of quantum-dot-sensitized one-dimensionally-ordered ZnO nanorod photocatalyst

An efficient photocatalyst was fabricated by assembling quantum dots （QDs） onto one-dimensionally-ordered ZnO nanorods, and the photocatalytic properties for Methyl Orange degradation were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-Vis-NIR absorption spectroscopy and photoluminescence. The results indicate that the catalyst with assembled QDs is more favorable for the degradation than the pristine ZnO nanorods. The QDs with core-shell structure lower the photocatalytic ability due to the higher carder transport barrier of the ZnS shell layer. Besides its degradation efficiency, the photocatalyst has several advantages given that the one-dimensionally-ordered ZnO nanorods have been grown directly on indium tin oxide substrates. The article provides a new method to design an effective and easily recyclable photocatalyst.     

Preparation of MgO/B2O3 coatings by plasma spraying on SUS304 surface and effects of heat-resistant

This study mainly deals with the preparation of MgO/B₂O₃ coatings by plasma spraying on the SUS304 surface and the effects of heatresistant. The power materials of low thermal conductivity were selected to control the heat divergent performance of high temperature parts. The reticular micro-structure between the cover thermal layer and the substrate was prepared by using the plasma spraying method. The powder mixture of MgO and B₂O₃ were selected as spraying materials and the SUS304 was used as the substrate material. The MgO/B₂O₃ coating was prepared on the surface of the SUS304 to provide better cover thermal performance. The properties of the microstructures and the morphologies were studied by Optical Microscope, Scanning Electron Microscope, Electron Probe Microanalyzer, and X-ray Diffraction. The results showed that the cover thermal performance has been improved.     

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultraviolet-visible spectrophotometer within a range of 199–700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596°C.