Investigating the toxicity, microbial response and biogeochemical composition of gamma irradiated end products in oil sands process material

阿尔伯塔省东北部的油砂矿床是世界上最大的石油储量之一，在由沙子、粘土和水组成的矿物基质中，估计含有2.5万亿桶可开采的沥青。从挖掘的油砂中提取沥青的传统方法包括使用热水消化和浮选，产生由水、砂、细粒、残余沥青和石脑油组成的细尾浆，其中包括一种称为流体细尾（FFT）和油砂工艺水（OSPW）的物质。环烷酸（NA）是大多数石油的成分，包括在阿萨巴斯卡油砂中发现的石油。它们在环境中的存在会造成严重的问题，因为新释放的NAs对水生生物有毒。虽然毒性随环境中时间的推移而下降，但NA混合物的难熔成分可以持续数年。石油公司希望找到一种最佳的解决方案来处理FFT，减少和去除残留的NAs，使其能够安全地释放到自然环境中，并符合监管准则。我们的研究项目是调查高能伽马辐射对去除和减少NA混合物毒性的影响。初步的实验规模试验表明，OSPW组NAs减少95%，FFT组NAs减少50%。该研究项目将确认伽马辐射在分解OSPW和FFT中NA混合物方面的功效，评估实验室中对辐照材料的生物反应，并使用现场细胞监测自然环境中伽马处理的长期特性。以对环境负责的方式处置油砂加工废料，对于确保积极主动的区域环境管理至关重要，从而解决该区域的累积生物物理、健康和长期管理战略。这项研究的结果将有助于提高油砂运营商对废物处理的理解，并为环境敏感地区的可持续管理实践提供潜在的处理解决方案。

The oil sands deposits of north-eastern Alberta are one of the largest oil reserves in the world, containing an estimated 2.5 trillion barrels of recoverable bitumen held in a mineral matrix consisting of sand, clay and water. Traditional methods used to extract bitumen from excavated oil sands involve the use of hot water digestion and flotation which produces a fine tailing slurry consisting of water, sand, fines, residual bitumen and naphtha products comprising a material known as fluid fine tails (FFT) and oil sands process water (OSPW). Naphthenic acids (NA) are components of most petroleum, including those found in the Athabasca oil sands. Their presence in the environment can pose significant problems since freshly released NAs are toxic to aquatic organisms. Although toxicity declines with time in the environment, the refractory components of the NA mixture can persist for years. The oil companies are interested in finding an optimal solution to treat FFT and reduce and remove residual NAs so that it can be safely released into the natural environment and comply with regulatory guidelines. Our research program is investigating the effects of high energy gamma irradiation to remove and reduce the toxicity of NA mixtures. Preliminary bench scale trials have documented 95% reduction of NAs in OSPW and 50% reduction in the FFT. This research program will confirm the efficacy of gamma irradiation in breaking down NA mixtures in OSPW and FFT, assess biological responses to the irradiated materials in the laboratory, and use field cells to monitor the longer-term characteristics of the gamma treatments in a natural environment. Disposal of the oil sands process waste in an environmentally responsible fashion is paramount to ensuring proactive regional environment management that addresses the cumulative biophysical, health and long-term management strategy for the region. The outcomes generated by this research will contribute to an improved understanding of waste treatment for oil sands operators and provide potential treatment solutions for sustainable management practice in an environmentally sensitive region into perpetuity.