Metals vs Minerals: Impacts of atmospheric dust deposition on the speciation of trace elements in snowmelt and peatland surface waters

北方阿尔伯塔的露天沥青开采产生大量粉尘。粉尘不仅来自矿山，而且来自干尾矿和砾石道路的风蚀、建筑活动和采石场，以及河岸和沙洲等自然来源。粉尘本身主要由矿物颗粒组成，其中一些是化学反应性的（如方解石，碳酸钙），而其他则是有效的不溶性（如石英，硅酸盐）。人们还一直担心沥青开采和升级过程中可能会向大气中释放有毒的“重金属”，但这些排放的程度及其生态意义尚不清楚。迄今为止，大多数环境影响研究尚未明确区分沥青升级所需的化石燃料燃烧产生的重金属（如镉和铅）与矿物颗粒本身晶格中的重金属。在高温燃烧过程中排放到空气中的重金属往往非常小（< 1微米），并且是可溶形式（如氧化物），而机械产生的矿物粉尘往往相当大（10至100微米），并且溶解度低得多（如石英和长石等硅酸盐矿物）。非常小的可溶性含金属颗粒可能对生物群构成威胁，这取决于土壤和水的pH值以及其他因素，但大的不溶性颗粒很可能不会。本研究的主要目标是通过对雪和沼泽中的泥炭藓进行尺寸分辨分析，清楚地区分空气中重金属的这两种来源。第二个目标是了解什么样的影响，如果有的话，这两个来源的重金属可能有融水和泥炭地表面沃茨（从沼泽，沼泽和沼泽）的化学成分排入阿萨巴斯卡河。

Open pit bitumen mining in northern Alberta generates considerable volumes of dust. The dusts are derived not only from the mines, but from wind erosion of dry tailings and gravel roads, construction activities, and quarries, in addition to natural sources such as river banks and sand bars. The dusts themselves consist mainly of mineral particles, some of which are chemically reactive (e.g. calcite, a calcium carbonate) whereas others are effectively insoluble (such as quartz, a silicate). There are also ongoing concerns about potentially toxic "heavy metals" being released to the atmosphere from bitumen mining and upgrading, but the extent of these emissions, and their ecological significance, is unclear. Most environmental impact studies to date have not clearly distinguished between heavy metals (such as cadmium and lead) from the combustion of fossil fuels needed for bitumen upgrading versus heavy metals which are hosted within the crystal lattice of the mineral particles themselves. Heavy metals which are emitted to the air during combustion at high temperatures tend to be very small (< 1 micron) and in soluble form (such as oxides), whereas mechanically-generated mineral dusts tend to be rather large (10 to 100 microns) and much less soluble (e.g. silicate minerals such as quartz and feldspar). Very small, soluble, metal-containing particles may represent a threat to biota, depending on the pH of soil and water, and other factors, but large, insoluble particles most likely do not. The main goal of this study is to clearly distinguish between these two sources of heavy metals to the air, using size-resolved analyses of snow and Sphagnum moss from bogs. The secondary objective is to understand what impact, if any, the two sources of heavy metals may have for the chemical composition of meltwater and peatland surface waters (from bogs, fens and swamps) which drain into the Athabasca River.