Fine sediment dynamics in Quesnel Lake: the regulation of contaminant and nutrient transfers from the Mt Polley mine spill

克内尔湖的精细沉积物动态：波利山矿山泄漏污染物和养分转移的调节

基本信息

批准号：
RGPIN-2019-07289
负责人：
Petticrew, Ellen
金额：
$ 3.13万
依托单位：
University of Northern British Columbia
依托单位国家：
加拿大
项目类别：
Discovery Grants Program - Individual
财政年份：
2019
资助国家：
加拿大
起止时间：
2019-01-01 至 2020-12-31
项目状态：
已结题

来源：
https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688632
关键词：
Fine sediment dynamics Quesnel Lake

项目摘要

In August 2014, Canada's largest mining disaster occurred at the Mt Polley copper-gold mine, near Likely, British Columbia. The tailings pond wall breached, releasing 25 Mm3 of tailings, wastewater and construction materials. Further scouring of vegetation and surface materials occurred along a 9 km reach before entering the west basin of Quesnel Lake. Polley Lake, a smaller lake adjacent to the tailings pond was also dosed with tailings but remained off limits to researchers for the first year. This proposal aims to assess fine sediment processes regulating contaminant (metals/metalloids) and phosphorus (P) dynamics and their medium-term effects on foodwebs in both Quesnel and Polley Lakes. Observations from a 2016 core sampling program along a lake transect incorporating the tailings deposit and further afield indicated a layer, several millimeters to tens of centimeters thick, of flocculated surface material that remained unconsolidated above either natural sediments or tailings material. This material was experimentally found to be very mobile and therefore likely to be reintroduced into the water column at various times of the year, potentially during seiching (wind-mixing) events and fall and winter turnovers. The quality of this resuspended sediment will have an impact on the lake functioning in that it contains a large mass of phosphorus (~5% wt) as well as metals both of which can be problematic for aquatic organisms in excess. The bioavailability of these contaminants will be dependent upon the chemical and erosive conditions at the sediment-water interface. Seasonal changes in both of these variables will regulate if sediment-associated nutrients are available for in-lake primary production and if sediment-associated contaminants are incorporated by filter feeding invertebrates, which are a main food source for the sport and salmonid fishes in the lake.***The uniqueness of this proposed project is the evaluation of a catastrophic event providing full-lake fertilization, but delivered in concert with high loads of metal and metalloids. While the phosphorus introduced in the tailings waste may act as a fertilizer increasing primary production in this lake, these organisms may also incorporate metals, thereby magnifying their impact within the foodweb. As most of the metals from the Mt Polley spill have been identified as being sediment-associated, the fate of these unconsolidated flocculated sediments at the sediment-water interface is in question. A series of field and laboratory projects will be undertaken by Petticrew and her HQP over the next five years to address these issues. This project will also provide valuable information on the resiliency of large and medium-sized lake ecosystems to massive disturbances such as those associated with mining disasters, and other similar events in pristine watersheds, thereby helping to protect Canada's aquatic ecosystems. **

2014年8月，加拿大最大的矿难发生在不列颠哥伦比亚省莱克利附近的波利山铜金矿。尾矿库池壁破裂，释放出25立方米的尾矿、废水和建筑材料。在进入克内尔湖西部盆地之前，沿 9 公里河段对植被和地表物质进行了进一步冲刷。波利湖是一个毗邻尾矿池的较小湖泊，也添加了尾矿，但第一年仍然禁止研究人员进入。该提案旨在评估调节污染物（金属/类金属）和磷（P）动态的精细沉积物过程及其对康内尔湖和波利湖食物网的中期影响。 2016 年沿包含尾矿沉积物和更远地区的湖泊横断面进行的岩心取样计划的观察结果表明，在天然沉积物或尾矿材料上方有一层几毫米到几十厘米厚的絮凝表面材料，该材料在天然沉积物或尾矿材料上方仍未固结。实验发现这种材料具有很强的流动性，因此可能在一年中的不同时间重新引入水体，可能是在风混合事件和秋冬季节更替期间。这种重新悬浮的沉积物的质量将对湖泊的功能产生影响，因为它含有大量的磷（约 5% wt）以及金属，这两种物质过量都会给水生生物带来问题。这些污染物的生物利用度将取决于沉积物-水界面的化学和侵蚀条件。这两个变量的季节变化将调节与沉积物相关的营养物质是否可用于湖内初级生产，以及与沉积物相关的污染物是否被滤食性无脊椎动物吸收，滤食性无脊椎动物是湖中运动鱼类和鲑鱼的主要食物来源.***该拟议项目的独特性是对灾难性事件的评估，该事件提供了全湖施肥，但与高负荷的金属和准金属相结合。虽然尾矿废物中引入的磷可能充当肥料，增加该湖的初级生产，但这些生物也可能含有金属，从而扩大了它们在食物网中的影响。由于波利山泄漏事故中的大部分金属已被确定为与沉积物有关，因此沉积物-水界面上这些未固结的絮凝沉积物的命运受到质疑。 Petticrew 及其总部将在未来五年内开展一系列现场和实验室项目来解决这些问题。该项目还将提供有关大中型湖泊生态系统对大规模扰动（例如与采矿灾害和原始流域中其他类似事件相关的扰动）的恢复能力的宝贵信息，从而有助于保护加拿大的水生生态系统。 **