Estimation of mercury content in tailings of the gold mine area of Poconé, Mato Grosso,Brazil

As in many other parts of the world, gold is produced in the surface mining region of Poconé, Mato Grosso, Brazil, using mercury. The goal of this investigation was to estimate the amount of mercury in certain tailings and to determine the area of the land that has been contaminated by the gold mining operations. Mercury concentrations from 2 to 495 ng/g (dw) were determined in the tailing materials. It was observed that only isolated sites were acting as central points of contamination. Using digital Landsat satellite data (The-matic Mapper) and aerial photos, the sites degraded by the mining were classified, and their total area was estimated to be 12.3 km² in the region of Poconé. It was estimated, that 4.9 km² were occupied by the contaminated tailings. The mean height of the pile slags was determined to be 4.5 m. From the experimentally calculated average density of the material in the tailings, 2.01 g/cm³, the total mercury content in the piles of tailings was estimated to be 1600 ± 350 kg.     

SiO2纳米颗粒内嵌强化介孔TiO2单晶光催化降解盐酸四环素

吸附性能和光生载流子的分离效率是决定光催化降解抗生素的主要因素.为提高介孔TiO_2单晶(MSCs)的吸附性能和光生载流子的分离效率,在MSCs内部构建SiO_2纳米颗粒吸附结构.同时,利用表面光电压谱、氮气等温吸附-脱附、X射线衍射等研究其结构特性.最后,以盐酸四环素为抗生素代表,通过控制SiO_2纳米颗粒比表面积,考察SiO_2对复合材料吸附及光催化性能的影响.结果表明,SiO_2纳米颗粒与TiO_2单晶复合显著提高了材料的吸附性能,表面保护蚀刻进一步提升了材料的比表面积.实验条件下,高比表面积SiO_2-TiO_2单晶复合材料(KSiO_2@TiO_2)对盐酸四环素的平衡吸附量、降解效率、降解速率常数和矿化率分别达到了0.96 mg·g-1、90.2%、0.0079 min-1、54.4%,分别是MSCs的4.4、1.5、2.6和3.1倍.副产物分析表明,SiO_2复合介孔单晶材料更易将盐酸四环素降解为小分子物质.     

Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experiments were performed to explore the impact of sulfur nanoparticles (SNPs) on growth, Cu accumulation, and physiological and biochemical responses of oilseed rape (Brassica napus L.) inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure. Cu exerted severe phytotoxicity and inhibited plant growth. SNPs application enhanced the shoot height, root length, and dry weight of shoot and root by 34.6%, 282%, 41.7% and 37.1%, respectively, over Cu treatment alone, while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde (MDA) levels in shoots and roots were decreased by 37.6%, 35%, 28.4% and 26.8%. Further, the increases in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities caused by Cu stress were mitigated in shoots (10.9%–37.1%) and roots (14.6%–35.3%) with SNPs addition. SNPs also positively counteracted the negative effects on shoot K, Ca, P, Mg, Mn, Zn and Fe contents and root K, Ca, Mg and Mn contents from Cu exposure alone, and significantly promoted the nutrients accumulation in plant. Additionally, in comparison with common bulk sulfur particles (BSPs) and sulfate, SNPs showed more positive effects on promoting growth in shoots (6.7% and 19.5%) and roots (10.9% and 15.1%), as well as lowering the shoot Cu content (40.1% and 43.3%) under Cu stress. Thus, SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.     

金属离子修饰纳米TiO2薄膜光催化降解苯酚

通过溶胶-凝胶法制备纳米TiO2薄膜，在制备过程中分别掺杂一定量的Fe^3 、Zn^2 、Pd^2 等金属离子。以高压汞灯做光源，用制得的纳米TiO2薄膜对苯酚作光催化降解实验，结果表明：掺杂Fe^3 、Zn^2 、Pd^2 的纳米TiO2催化剂光催化性能明显提高。并探讨了金属离子掺杂浓度和氧化剂对光催化的影响。     

黄铁矿晶体形态模拟实验研究

采用实验方法模拟金矿床成矿作用条件,研究水热体系黄铁矿各种晶体形态生成的物理化学条件,着重阐述黄铁矿的五角十二面体、八面体、立方体等晶形形成环境因素。实验成果有助于找矿矿物学、成因矿物学的发展和金矿的找矿和勘探。     

Allium cepa root tip assay in assessment of toxicity of magnesium oxide nanoparticles and microparticles

Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide(MgO) particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano-and microparticles(NPs and MPs) at a range of exposure concentrations(12.5, 25, 50, and100 μg/m L). The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index(MI) when compared to control cells and the effect was more significant for NPs than MPs(at p 0.05). Comet analysis revealed that the Deoxyribonucleic acid(DNA) damage in terms of percent tail DNA ranged from 6.8–30.1 over 12.5–100 μg/m L concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.     

用乳状液膜法从镀金废液中回收金的研究

报道了用乳状液膜法从镀金废液中回收金的研究，分析了各种工艺条件的影响，在最佳实验条件下，经一级间歇式液膜分离在内水相获得纯度为９９．９％的单质金，收率为９９．１％，本法具有流程短、速度快和效率高的特点，具有工业应用前景。     

磁性纳米颗粒对不同模式生物的毒性研究

磁性纳米颗粒在生物医学等领域应用广泛,而其毒性研究尚未深入,对生物的影响及作用机制仍未阐明。本文综述了磁性纳米颗粒近年来对于细胞、鼠、家兔和秀丽隐杆线虫的毒理学研究,为磁性纳米颗粒的应用提供参考。     

量子点对Cu2+诱导L02细胞毒性的影响及机理研究

量子点(QDs)和Cu~(2+)可能共存于肝脏,对肝细胞产生联合毒性,威胁人体健康。本研究以人胚肝细胞(L02)为研究对象,考察了低/无毒的QDs(3.6%的细胞致死率)对Cu~(2+)诱导L02细胞毒性的影响及相关机理,为其可能的健康和环境风险提供参考。结果显示,QDs的加入使得Cu~(2+)的细胞毒性有了很大的提高,细胞存活率最高下降了26.0%,两者表现为协同作用;另外QDs存在使得Cu~(2+)细胞蓄积量增大,伴随着Cu~(2+)天然解毒蛋白CTR1和ATP7A等表达水平的升高,从侧面印证了Cu~(2+)的蓄积量增加对细胞的影响;同时,QDs的存在使得细胞乳酸脱氢酶(lactate dehyfrogenase,LDH)泄露相对于Cu~(2+)单独处理组提高,暗示QDs可能破坏了细胞膜,导致Cu~(2+)在细胞内蓄积量增加,从而使细胞毒性增加,两者的联合毒性表现为协同作用。     

Influence of phosphate on deposition and detachment of TiO2 nanoparticles in soil

We examined influence of phosphate on transport of TiO₂ NPs in soil. Deposition was reduced at higher pH and by adsorption of phosphate in soil. Release was more for NPs initially deposited at higher pH. Release was more for NPs initially deposited in the presence of phosphate. Surface roughness and charge heterogeneity play a role in the deposition/ release. The widespread use of TiO₂ nanoparticles (NPs) makes inevitable their release into the soil. Phosphate is also widespread within soil, and is likely copresent with TiO₂ NPs. However, the influence of phosphate on deposition/release— and thereby on transport— of TiO₂ NPs in soil is yet to be elucidated. In this study we conducted saturated column experiments to systematically examine the transport of TiO₂ NPs in soil amended with phosphate at different ionic strengths (ISs) (1, 10, 100 mmol/L NaCl) and pHs (4 and 9). Results show that the deposition of TiO₂ NPs decreased with decreasing IS, increasing pH, and when soil absorbed phosphate. These observations are qualitatively in agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations, because the repulsive energy barrier is larger and secondary minimum depth is smaller at a lower IS, higher pH, and in the presence of phosphate. Accordingly, both primary- and secondary-minimum deposition were inhibited. Interestingly, although the deposition was less at higher pH and in the presence of phosphate, the subsequent spontaneous detachment and detachment by reduction of solution IS in these cases were greater. In addition, the presence of phosphate in the solution can cause a small quantity of attached TiO₂ NPs to detach, even without perturbations of physical and chemical conditions. Our study was the first to investigate the influence of phosphate on detachment of TiO₂ NPs and the results have important implication for accurate prediction of fate and transport of TiO₂ NPs in subsurface environments.