Size-dependent characterisation of historical gold mine wastes to examine human pathways of exposure to arsenic and other potentially toxic elements

Abandoned historical gold mining wastes often exist as geographically extensive, unremediated, and poorly contained deposits that contain elevated levels of As and other potentially toxic elements (PTEs). One of the key variables governing human exposure to PTEs in mine waste is particle size. By applying a size-resolved approach to mine waste characterisation, this study reports on the proportions of mine waste relevant to human exposure and mobility, as well as their corresponding PTE concentrations, in four distinct historical mine wastes from the gold province in Central Victoria, Australia. To the best of our knowledge, such a detailed investigation and comparison of historical mining wastes has not been conducted in this mining-affected region. Mass distribution analysis revealed notable proportions of waste material in the readily ingestible size fraction (≤250 µm; 36.1–75.6 %) and the dust size fraction (≤100 µm; 5.9–45.6 %), suggesting a high potential for human exposure and dust mobilisation. Common to all mine waste types were statistically significant inverse trends between particle size and levels of As and Zn. Enrichment of As in the finest investigated size fraction (≤53 µm) is of particular concern as these particles are highly susceptible to long-distance atmospheric transport. Human populations that reside in the prevailing wind direction from a mine waste deposit may be at risk of As exposure via inhalation and/or ingestion pathways. Enrichment of PTEs in the finer size fractions indicates that human health risk assessments based on bulk contaminant concentrations may underestimate potential exposure intensities.     

Degradation of octylphenol and nonylphenol by ozone - part II: indirect reaction

The indirect reaction of octylphenol (OP) and nonylphenol (NP) with hydroxyl radicals (*OH) during ozonation was investigated at pH values ranging from 6 to 9. A parameter Rct, representing the ratio of the *OH-exposure to the ozone-exposure, was measured using a method involving a low concentration of p-chlorobenzoic acid as a *OH-probe compound during the ozonation. By assuming that Rct is a constant value at a given pH, the second order rate constants of the alkylphenol reaction with hydroxyl radicals were determined as 1.4(+/-0.2) x 10(10) and 1.1(+/-0.2) x 10(10) M(-1) s(-1) for OP and NP, respectively. The proportions of each alkylphenol degraded by direct molecular ozone reaction and indirect hydroxyl radical reaction were predicted at different pH values. The contribution of indirect *OH reactions with each AP was found to represent over 50% of the total degradation for pH approximately 7, and the contribution increases substantially with pH>7.     

气候变化对波罗的海入海河流流量的影响

进入波罗的海的河流流量是在一个面积约160万km2的流域中各种不同气候状况下产生的.波罗的海流域气候的变化不仅影响入海淡水的总量,而且对这些水源的分配亦有影响.利用水文模拟,分析了未来气候变化对波罗的海入海径流的影响.使用了瑞典区域气候模拟计划(SWECLIM)中的4种不同的气候变化情景.根据这些不同的气候情景,全部入海河流总的平均年入海量的变化范围为当前入海量的-2%～+15%.波罗的海不同亚区的入海量的变化是大不相同的,其中最剧烈的年均变化范围是-30%～+40%.但是,所有评价的气候情景的共同点是总体趋势为来自波罗的海流域南部地区入海流量减少,北部地区入海量增加.     

Characterization of Fugitive Material within a Primary Lead Smelter

ABSTRACT

The primary production of Pb via the sinter plant-blast furnace method resulted in a large number of Pb and other phases, reflecting the complex reactions occurring within each of the processes. Optical microscopy and X-ray diffraction (XRD) techniques have been used to characterize fugitive emissions and dusts generated during sintering, smelting, Cu drossing, refining, and slag fuming at a primary Pb-Zn smelter. The results displayed a complex array of phases, with the mineralogy of the dusts and fume reflecting conditions of the particular metallurgical operation. The principal Pb species followed a transformation from PbS through PbSO₄ and PbO to Pb° (metal) from raw materials to the refinery. The fugitive emissions generated by the blast furnace were of a finer size with more complex chemistry than fugitive material from other source areas. XRD identified a mixture of PbS, ZnO, and ZnS, associated with one or more of the Cl-bearing phases Pb(OH)Cl, PbCl₂, Pb₄O₃Cl₂, Na₃Pb₂(SO₄)₃Cl, Pb₁₀(SO₄)Cl₂O₈, Pb₄SCl₆, and Pb₇S₂Cl₁₀. The presence of Cl-bearing phases in the fume has possible health implications.     

Nitrous oxide emissions from light duty vehicles

Nitrous oxide (N₂O) emissions measurements were made on light duty gasoline and light duty diesel vehicles during chassis dynamometer testing conducted at the Environment Canada and California Air Resources Board vehicle emissions laboratories between 2001 and 2007. Per phase and composite FTP emission rates were measured. A subset of vehicles was also tested using other driving cycles to characterize emissions as a function of different driving conditions. Vehicles were both new (<6500 km) and in-use (6500–160,000 km) and were tested on low sulfur gasoline (<30 ppm) or low sulfur diesel (<300 ppm). Measurements from selected published studies were combined with these new measurements to give a test fleet of 467 vehicles meeting both US EPA and California criteria pollutant emissions standards between Tier 0 and Tier 2 Bin 3 or SULEV. Aggregate distance-based and fuel-based emission factors for N₂O are reported for each emission standard and for each of the different test cycles. Results show that the distinction between light duty automobile and light duty truck is not significant for any of the emission standards represented by the test fleet and the distinction between new and aged catalyst is significant for vehicles meeting all emission standards but Tier 2. This is likely due to the relatively low mileage accumulated by the Tier 2 vehicles in this study as compared to the durability requirement of the standard. The FTP composite N₂O emission factors for gasoline vehicles meeting emission standards more stringent than Tier 1 are substantially lower than those currently used by both Canada and the US for the 2005 inventories. N₂O emission factors from test cycles other than the FTP illustrate the variability of emission factors as a function of driving conditions. N₂O emission factors are shown to strongly correlate with NMHC/NMOG emission standards and less strongly with NO_X and CO emission standards. A review of several published reports on the effect of gasoline sulfur content on N₂O emissions suggests that additional research is needed to adequately quantify the increase in N₂O emissions as a function of fuel sulfur.     

Claiming a corner at work: Measuring employee territoriality in their workspaces

Territoriality is an emerging concept of importance in organizations. Unfortunately, there does not exist currently a valid measure of territoriality with which to conduct research on territoriality in organizations. I developed a theoretically driven four-factor measure of territoriality. Six hundred and sixty-three people working in office settings completed an online survey about their territorial behaviors. Using confirmatory factor analysis I found that the four-factor structure had acceptable fit. I also found preliminary evidence of construct validity. Collectively, the results support the validity of the measure, thus providing an instrument for studying territoriality in organizations. I then discuss specific implications of this measure for both research and practise.     

Provenancing anthropogenic Pb within the fluvial environment: developments and challenges in the use of Pb isotopes

The potentially deleterious presence of ore-derived Pb within riverine environments has been a long-term impact of industrial and anthropogenic activity in general. The surface drainage network has been widely established as a key transport mechanism and storage environment for anthropogenically-derived Pb and other potentially harmful trace metals. Lead isotopes ((204)Pb, (206)Pb, (207)Pb, (208)Pb) have been utilized as a geochemical tracer of Pb origin in a variety of environmental media, notably in atmospheric aerosols. However, given the relative complexity of dispersal processes within riverine environments, the use of Pb isotopes as geochemical tracers has been relatively limited and it is only relatively recently that a growing body of research has applied Pb isotopes to provenancing fluvially-dispersed Pb. This paper seeks to synthesize the developments in the use of Pb isotopes within riverine environments. In doing so it outlines the Pb-isotope fingerprinting technique and associated analytical developments, and assesses the application of Pb isotopes in establishing the origin and dispersal mechanisms of anthropogenically- and geogenically-derived Pb at a range of temporal and spatial scales. Of particular importance are the approaches quantifying source inputs using Pb isotopic signatures and the challenges faced, and options available in quantifying source inputs at the catchment scale; where Pb may be sourced from a variety (n=>2) of sources. The Pb isotopic signature of contemporary riverine Pb loads is shown to reflect a spatially complex influence of mineralization chemistry, anthropogenic activity as well as the hydro-morphological controls exerted upon Pb release, dispersal and storage. In relation to this, the long-term environmental legacy, and its influence upon Pb fingerprinting studies, of tetra-ethyl Pb, sourced from the combustion of leaded-petrol is also discussed. Finally, this paper places the use of Pb isotopes in the context of recently developed Cu and Zn isotopic fingerprinting techniques and assesses the role of Pb, Cu and Zn isotopes in a multi-proxy approach to geochemical tracing.     

The demography of feral alfalfa (<Emphasis Type="BoldItalic">Medicago sativa</Emphasis> L.) populations occurring in roadside habitats in Southern Manitoba,Canada: implications for novel trait confinement

Purpose  

Feral populations of cultivated crops can act as reservoirs for novel genetically engineered (GE) traits and aid in trait movement at the landscape level. However, little information is available on the potential of cultivated crops to become feral. In this study, we investigated the ferality of alfalfa populations (non-GE version) occurring in roadside habitats. Knowledge on the nature of roadside alfalfa populations would be useful for designing efficient trait confinement protocols and coexistence strategies in alfalfa.