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101.
Isotopic measurements of the 34 m3/s discharge from the Fall River Springs of northern California indicate recharge from 50 km upgradient in high elevation regions of Medicine Lake Volcano. Age determinations suggest less than 20-year travel time. Data demonstrate Klamath Basin further north cannot be a recharge source. Mass balance calculations support that annual precipitation on the volcano supplies observed spring discharge, requiring 50%–75% recharge rates. Radiocarbon and δ13C of dissolved inorganic carbon indicate 30%–40% is derived from magmatic CO2. Measured excess 3He is also consistent with the presence of magmatic gas derived from the Quaternary Age Medicine Lake Volcano. 相似文献
102.
Rebecca L. Curtis 《Environmental Forensics》2014,15(4):293-295
Gold (Au) accounts for only 0.004 g/ton of the earth's crust and is the most desired element. With an average annual world production of approximately 2,500 tons, the current methods of Au mining in developing countries cause major environmental issues. These issues vary from deforestation to cyanide and mercury (Hg) contamination. This article presents several cases of environmental catastrophes caused by Au mining in different regions of the world (Africa, the Middle East, Eastern Europe, and South America). It discusses the currently available processes for the large-scale extraction of metallic Au grains and supports the need for an alternative sustainable process. 相似文献
103.
Polybrominated diphenyl ethers (PBDEs) and mercury in fish from lakes of the Tibetan Plateau 总被引:2,自引:0,他引:2
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. 相似文献
104.
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. 相似文献
105.
兰州城区大气粒子态汞的污染状况 总被引:8,自引:0,他引:8
通过调查发现在市工业区,粒子态汞浓度高,冬,夏平均值为0.91和1.00ng/m^3,最高达1.92ng/m^3,冬夏季无显著性差异,秋季浓度低,交通频繁区和交通商业混合区冬季平均值0.45ng/m^3,夏季0.49ng/m^3在清洁区大部分在0.10ng/m^3左右,最低0.070ng/m^3,显示夏季和城区粒子态汞浓度偏高的特征。工业区粒子态汞主要是由人为污染产生的气态汞吸附在同一污染源的粒尘 相似文献
106.
Huan Zhong 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):981-986
This study compared the relative importance of three types of sorption (organic matter-particle, mercury-organic matter and mercury-particle) in controlling the overall mercury partitioning and bioavailability in sediments. We found that all three types of sorption were important for both inorganic mercury (Hg) and methylated mercury (MeHg). Mercury-particle sorption was more important than mercury-fulvic acid (FA) sorption in increasing the mercury concentrations with increasing aging. Bioavailability (quantified by gut juice extraction from sipunculans) was mainly controlled by mercury-particle sorption, while FA-particle and mercury-FA sorption were not as important, especially for MeHg. Bacterial activity also increased the partitioning of Hg or MeHg in the sediments and was further facilitated by the presence of organic matter. The bioavailability of Hg or MeHg from sediments was only slightly influenced by bacterial activity. This study highlights the importance of sorption from various sources (especially mercury-particle sorption) as well as bacteria in controlling the partitioning and bioavailability of Hg or MeHg in sediments. 相似文献
107.
Dariusz Guziejewski Mariola Brycht Agnieszka Nosal-Wiercińska Sylwia Smarzewska Witold Ciesielski Sławomira Skrzypek 《Journal of environmental science and health. Part. B》2013,48(8):550-556
The electrochemical behavior of new generation fungicide acibenzolar-s-methyl (S-methyl 1,2,3-benzothiadiazole-7-carbothioate, ASM) on the hanging mercury drop electrode (HMDE) was investigated using square wave adsorptive stripping voltammetry. This method of determination is based on the irreversible reduction of ASM at the HMDE. The well-defined ASM peak was observed at ?0.4 V (vs. Ag/AgCl) in BR buffer at pH 2.2. The reduction peak current was proportional to concentration of ASM from 1.0 × 10?8 to 6.0 × 10?8 mol L?1 with detection and quantification limit 3.0 × 10?9 and 1.0 × 10?8 mol L?1, respectively. The applicability of the developed method for analysis of spiked samples of tap water, river water, and soil is illustrated. The effect of adsorption on the mercury electrode was studied in detail using the AC impedance method. Possible interferences with other common pesticides and heavy metal ions were examined. Clarification of the electrode mechanism was made using cyclic voltammetry (CV) technique. 相似文献
108.
Július Árvay Ján Tomáš Martin Hauptvogl Miriama Kopernická Anton Kováčik Daniel Bajčan 《Journal of environmental science and health. Part. B》2013,48(11):815-827
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. 相似文献
109.
110.
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。 相似文献