Contamination of wild-grown edible mushrooms by heavy metals in a former mercury-mining area

The aim of this study was to evaluate the contamination of six edible wild species of mushrooms (Boletus pulverulentus, Cantharellus cibarius, Lactarius quietus, Macrolepiota procera, Russula xerampelina and Suillus grevillei) by heavy metals (Hg, Cd, Pb, Zn, Cu, Ni, Cr, Co, Mn and Fe). Mushroom samples were collected from sites contaminated by emissions from mining and processing of polymetallic ores in operation during the period 1969–1993 in Rudňany, southeast Slovakia. The four study sites spanned up to a 5-km distance from the emission source. The collected mushroom samples were analyzed using Flame Atomic Absorption Spectrophotometry and/or Flame Atomic Absorption Spectrophotometry with graphite furnace. Mercury, Cd and, in some samples, also Pb present the highest risks in terms of contamination of the food chain following subsequent consumption. The content of two metals in the dry matter (dm) of the mushrooms exceeded the limits set by the European Union (EU; Cd: 0.5 mg/kg dm, Pb: 1.0 mg/kg dm). The highest mean contents of the eight metals recorded for S. grevillei were 52.2, 2.15, 107, 104, 2.27, 2.49, 81.6 and 434 mg/kg dm for Hg, Pb, Zn, Cu, Ni, Cr, Mn and Fe, respectively. The highest content of Cd was recorded in M. procera (3.05 mg/kg dm) and that of Co in L. quietus (0.90 mg/kg dm). The calculated weekly intake for Hg, Pb and Cd shows that regular consumption of mushrooms from the studied area poses risks to human health.     

高压实新疆阿尔泰膨润土微观结构随吸力变化特征

采用压汞法(MIP)和扫描电镜(SEM)法,在自由和侧限状态下,试验研究了高压实新疆阿尔泰膨润土在不同吸力条件下的微观结构变化特征。吸力的控制采用了气相法和渗析(液相)法。研究结果表明:(1)低吸力范围内,自由膨胀和侧限条件下的高压实膨润土土水特征存在明显差异;(2)膨润土在自由和侧限状态下的水化过程中呈现出了截然不同的微结构变化特征。自由膨胀条件下,土的吸水膨胀量主要来自土中大孔隙的逐渐膨胀。侧限状态下,随着控制吸力的降低,膨润土的大孔隙逐渐被压缩,较小孔隙的数量不断增加,土中孔隙分布变得更加均匀。     

正交试验-硝酸微波消解-冷原子吸收法测定土壤中汞

应用硝酸微波消解土壤样品-冷原子吸收法测定土壤中的汞。通过正交试验,优化了土壤中汞的微波消解条件。并对干扰消除、方法精密度、加标回收、检出限进行了试验研究。在0～10μg／L范围内线性关系良好,方法测定下限为0．20μg／L,土壤中汞的检出限为0．005μg／g。该优化条件对汞含量为0．02—0．46μg／g的土壤样品,汞提取完全。建立了一种简便、成本低、干扰少、灵敏度高的方法。     

电厂燃煤过程中汞控制技术研究

燃煤电厂汞控制技术分燃烧前、燃烧中和燃烧后脱汞,燃烧后脱汞技术为主要汞控制排放工艺,其中吸附剂吸附方法的研究较为广泛。基于国内外近几年燃煤电厂烟气脱汞技术的研究,综述了汞控制技术的最新进展。     

CuO-CeO2/AC吸附燃煤烟气中元素汞的实验研究

通过活性炭负载CuO和CeO2来制备吸附剂,采用固定床吸附方式,在不同反应条件下对吸附剂的吸附性能进行测试,筛选出去除效率最好的吸附剂,并通过BET和XRD对吸附剂的理化性质进行分析。结果表明,CuO和CeO2的加入大大改变了原活性炭的比表面积和孔结构,改善了活性炭的吸附性能。CuO-CeO2/AC中CuO和CeO2质量比不同,对汞的去除效率也不同,在1∶2时去除效率最好;CuO-CeO2/AC中所负载的CuO和CeO的总量为5%时,能大大促进汞的吸附效率,增长有效吸附时间;CuO-CeO2/AC对汞的吸附性能随反应温度的增加呈先增加后减小的趋势,在80℃时达到最大值。     

苯胺-邻氨基酚共聚物对水中Hg(Ⅱ)吸附性能的研究

利用化学氧化法合成了苯胺-邻氨基苯酚的共聚物,并通过静态实验研究了材料对水中汞离子的吸附性能。研究结果表明,该共聚物对废水中汞离子有优异的去除效果,其吸附容量可达212.13 mg/g;吸附等温线符合Langmu ir单层吸附模型,动力学过程符合准二级动力学模型;溶液pH值对吸附影响不是很大,pH 5~10范围都有较好的吸附效果;氯离子易与汞离子形成水溶性更强的络合物,对共聚物的吸附有很大的抑制作用。     

原子吸收法直接测量土壤中的汞含量

实验采用DMA-80自动测汞仪直接测定土壤中的汞含量,详细介绍了土壤样品中汞分析条件的选择,方法在0．4—400ng范围内,线性良好,其检出限为0．2ug／kg。     

Temporal patterns of atmospheric mercury species in northern Mississippi during 2011–2012: Influence of sudden population swings

Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were measured on the University of Mississippi campus from July 2011 to June 2012. It is believed to be the first time that concentrations of atmospheric mercury species have been documented in northern Mississippi, and at a location with relatively large and sudden swings in population. The mean concentration (±1SD) of GEM was 1.54 ± 0.32 ng m⁻³; levels were lower and generally more stable during the winter (1.48 ± 0.22) and spring (1.46 ± 0.27) compared with the summer (1.56 ± 0.32) and fall (1.63 ± 0.42). Mean concentrations for GOM and PBM were 3.87 pg m⁻³ and 4.58 pg m⁻³, respectively; levels tended to be highest in the afternoon and lowest in the early morning hours. During the fall and spring academic semesters concentrations and variability of GOM and PBM both increased, possibly from vehicle exhaust. There were moderate negative correlations with wind speed (all species) and humidity (GOM and PBM). Backward air mass trajectory modeling for the ten highest peaks for each mercury species revealed that the majority of these events occurred from air masses that passed through the northern continental US region. Overall, this study illustrates the complexity of temporal fluctuations of airborne mercury species, even in a small town environment.     

Polybrominated diphenyl ethers (PBDEs) and mercury in fish from lakes of the Tibetan Plateau

High mountains may act as cold traps for globally transported persistent organic pollutants (POPs) and mercury (Hg). In the present study, 60 fish samples were collected from eight alpine lakes across the Tibetan Plateau. Concentrations of polybrominated diphenyl ethers (PBDEs), total mercury (HgT) and methyl mercury (MeHg) were quantified in the fish muscle tissues to improve the understanding of pollution status and factors regulating the transport and fate of these contaminants on the Plateau. The results showed that lake-averaged ∑₁₄PBDEs concentration was between 0.09 ng g⁻¹ dw and 4.32 ng g⁻¹ dw, which was lower than those reported for European mountains. The total mercury concentration in individual fish ranged from 243 to 2384 ng g⁻¹ dw, and that of MeHg from 131 to 1610 ng g⁻¹ dw, which is much higher than those reported in other mountain fish. The spatial variation of PBDEs and mercury in the Plateau is largely controlled by the specific meteorological patterns.     

Polarity effect of pulsed corona discharge for the oxidation of gaseous elemental mercury

The effect of polarity on the oxidation of Hg⁰ was examined in the presence of O₂ via a pulsed corona discharge (PCD). The experimental result showed no difference in the energy yield of Hg⁰ oxidation at both positive and negative PCDs (∼8 μg Hg W h⁻¹ at following conditions: total flow rate = 2 L min⁻¹ (Hg⁰ = 50 μg N m⁻³, O₂ = 10%, and N₂ balance), temperature = 150 °C, and specific energy density = 5-15 W h N m⁻³). This suggests that the positive PCD process used to control gaseous air pollutants may play an essential key role in Hg⁰ oxidation because it consumes enough energy (∼15 W h N m⁻³) but an electrical precipitator could not because it consumes less energy (∼0.3 W h N m⁻³) to oxidize Hg⁰.