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

TerraX Minerals Inc.耶洛奈夫城市黄金项目，毗邻世界级的巨人（1945-2004年; 810万盎司）金矿，具有真实的潜力，以东道国的经济矿床存款。因此，公司必须在矿山开发之前预见到任何环境监管程序。历史上的矿物加工和废物处理做法造成了严重的环境污染（例如剧毒和生物可接受的三氧化二砷，As 2 O3）。不过，TerraX的资产包括金属浓度自然升高的岩石。在他们的整个主张中，湖泊中As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引起的金属再活化的任何组合造成的。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土地使用对主张范围内湖泊的影响。研究面临的挑战是为选定的湖泊确定地球化学基线，以评估未来的TerraX土地使用影响。到目前为止，在北部进行的唯一一次高分辨率地球化学研究是由我的小组在北卡罗来纳州的马修斯湖进行的。我们建议使用一种新的技术，建立在马修斯湖的结果。我们会继续采用取心方法，即在原地冻结沉积物并提取，从而消除传统取心装置对湖泊沉积物造成的干扰。我们将测试一种替代分析方法，该方法有可能大幅降低分析成本和吞吐时间。在马修斯湖，我们使用定制设计的切片机将冻结沉积物芯切成毫米级，以实现相当于每2-10年一次采样的时间采样分辨率，并使用ICP-MS分析来分析样品的金属含量。对于拟议的研究，而不是切片核心，我们将非破坏性地扫描他们在0.2毫米（每年）的分辨率使用新推出的ITRAX XRF扫描仪在麦克马斯特大学。通过这种新方法，我们将在提高确定地球化学基线和污染物随时间推移的变化率所需的岩心分析的吞吐量和可负担性方面迈出重要的一步（数量级），这是加拿大环境管理工作向前迈出的重要一步。

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.