Evaluation of a rapid, cost effective method to determine geochemical baseline in a legacy mining camp

泰拉克斯矿业公司黄刀市黄金项目毗邻世界级的巨型金矿（1945-2004；810万盎司），具有真正的经济矿床潜力。因此，公司必须在矿山开发之前预测任何环境监管程序。历史上的矿物加工和废物处理实践造成了大量的环境污染（例如剧毒和生物可接近的三氧化二砷，As2O3）。不过，TerraX的属性包括天然金属含量较高的岩石。在他们的主张范围内，湖泊中砷和其他金属含量的升高可能是自然风化、过去的采矿活动或土地利用变化导致的金属再迁移的任何组合的结果。至关重要的是，在矿山开发之前，必须确定目前缺乏的地球化学基线和过去对主张范围内湖泊的土地利用影响。研究的挑战是确定选定湖泊的地球化学基线，以评估未来TerraX的土地利用影响。迄今为止，在北方进行的唯一高分辨率地球化学研究是由我的小组在新泽西州马修斯湖进行的。我们建议使用一种基于马修斯湖结果的新技术。我们将继续采用沉积物就地冻结提取的取心方法，从而消除传统取心设备对湖泊沉积物的干扰。我们将测试另一种分析方法，该方法具有显著降低分析成本和处理时间的潜力。在马修斯湖，我们使用我们定制设计的显微切片机在毫米尺度上切割冰冻沉积物岩心，以达到相当于每2-10年采样一次的时间采样分辨率，并使用ICP-MS分析样品的金属含量。在拟议的研究中，我们将使用麦克马斯特大学最新的ITRAX XRF扫描仪，以0.2毫米（年）分辨率对岩心进行非破坏性扫描，而不是切片岩心。通过这种新方法，我们将在提高岩心分析的吞吐量和可负担性方面迈出重大（数量级）一步，以确定地球化学基线和污染物随时间的变化率，这是加拿大环境管理的重要一步。

The TerraX Minerals Inc. Yellowknife City Gold Project, adjacent to the world-class Giant (1945-2004; 8.1 million oz.) gold mine, has real potential to host an economic ore deposit. The company must thus anticipate any environmental regulatory processes prior to mine development. Historical mineral processing and waste disposal practices created substantial environmental contamination (e.g. highly toxic and bioaccessible arsenic trioxide, As2O3). The TerraX property encompasses rocks with naturally elevated metal concentrations though. Elevated levels of As and other metals in lakes throughout their claims could result from any combination of natural weathering, past mining activities, or metal remobilization due to land-use changes. It is critical that geochemical baseline and past land-use impacts on lakes within the claims, currently lacking, be defined prior to mine development. The research challenge is to define geochemical baseline for selected lakes against which future TerraX land-use impacts can be assessed. The only previous high-resolution geochemical study carried out to date in the north was by my group at Matthews Lake, NT. We propose to use a new technique that builds on the Matthews Lake results. We will continue using a coring methodology where sediments are frozen in situ and extracted, thus eliminating disturbance of lake sediments caused by traditional coring devices. We will test an alternative analytical method with the potential to dramatically reduce analytical costs and throughput times. At Matthews lake we sliced the frozen sediment cores at mm-scale using our custom designed microtome, to achieve a temporal sampling resolution equivalent to a sample every 2-10 years, and analyzed the sample for their metal content using ICP-MS analysis. For the proposed research instead of slicing cores we will non-destructively scan them at 0.2 mm (annual) resolution using a newly available ITRAX XRF scanner at McMaster University. With this new approach we will make a major (order of magnitude) step in improving throughput and affordability of core analysis required to determine geochemical baseline and the rate of change of contaminants over time, a significant step forward in Canadian environmental stewardship.