An assessment of environmental geochemical baseline for Matthews Lake, Northwest Territories

西北地区马修斯湖环境地球化学基线评估

• 批准号: 461170-2013
• 负责人: Patterson, Tim
• 金额: $ 1.82万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Engage Grants Program
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=542482
• 关键词: assessment; environmental; geochemical; baseline; Matthews

The Seabridge Gold Inc. Courageous Lake exploration project (SCL) is located 240 km north Yellowknife in the central NT. Mining took place within the SCL claim at the Tundra (1964-1968) and Salmita (1983-1987) mines and ore was processed onsite. Levels of Arsenic (As) in the lake have consistently exceeded Canadian Council of the Ministers of the Environment guidelines. Elevated concentrations of As and other metals of concern (e.g., Al, Cd, Cu, Hg) in the lake could be the result of natural weathering, seepage from past mining activities, or a combination of both. A long-term sediment quality assessment of Matthews Lake is lacking and baseline pre-mining activity geochemistry for this region is not known. With two previous mine sites within the SCL site it is critical that geochemical baseline and past land-use impacts on the sediment quality of Matthews Lake be defined. It is nearly impossible to differentiate between baseline, past, and future land-use impacts on Matthews Lake using technologies currently employed for environmental monitoring due to the incredibly slow sedimentation rates within northern lakes. For example, Ekman grabs and Glew corers, commonly used to obtain lake sediments for analysis during site characterization and environmental monitoring, can produce samples that may homogenize up to 200 years of sediment accumulation, effectively mixing sediments deposited prior, during, and post mining. We propose using a technique where sediments are frozen in situ with a freeze corer and extracted, thus reducing or eliminating disturbance of lake sediments caused by traditional coring devices. We will slice frozen sediment cores at mm-scale with a custom designed microtome to achieve a temporal sampling resolution equivalent to a sample every 2-10 years. Our research is expected to provide site-specific environmental monitoring with specific emphasis on determining the proportions of anthropogenic and non-anthropogenic As. If this preliminary research is successful more detailed future research on multiple cores from around the lake may be used to account for sources of natural variability to be used to measure future chemical change and land-use impact on sediment quality.

Seabridge Gold Inc.勇敢的湖勘探项目（SCL）位于北部中部240公里。在Tundra（1964-1968）和Salmita（1983-1987）矿山和矿石的SCL索赔中进行了采矿。湖中的砷（AS）水平一直超过环境部长指南的加拿大理事会。 AS和其他关注金属的浓度升高（例如Al，Cd，Cu，Hg）可能是自然风化，过去采矿活动的渗漏或两者组合的结果。 缺乏对马修斯湖的长期沉积物质量评估，该地区的基线预矿活动地球化学尚不清楚。在SCL地点内的两个矿场上，必须定义地球化学基线和过去对Matthews Lake沉积物质量的土地利用影响的至关重要。由于北湖区内的沉积速度非常缓慢，使用目前用于环境监测的技术几乎不可能区分基线，过去和未来的土地利用影响。 例如，埃克曼（Ekman）抓取和gle液（通常用于在现场表征和环境监测过程中用于分析的湖泊沉积物），可以产生可能使多达200年的沉积物积累均匀的样品，有效地将沉积物沉积的沉积物混合在挖矿中。 我们建议使用一种技术，在该技术中，将沉积物用冷冻液将其原位冷冻并提取，从而减少或消除由传统加油装置引起的湖泊沉积物的干扰。我们将在MM尺度上切成冷冻的沉积物岩心，并使用定制设计的微型集成体，以每2-10年获得相当于样品的时间采样分辨率。 我们的研究有望提供特定地点的环境监测，并特别强调确定人为和非人为的比例AS。 如果这项初步研究成功地取得了成功的详细详细研究，未来对来自湖泊周围多个核心的研究可能会用来解释自然变异性的来源，以衡量未来的化学变化和土地利用对沉积物质量的影响。