Assessment of contaminant loadings in lake sediments using magnetic property measurements

加拿大和美国管理机构认为，五大湖污染沉积物的补救是一项紧迫的环境优先事项。42个关注区已经确定，湖底沉积物受到重金属、碳氢化合物和一系列其他环境污染物的污染，达到有毒水平。这些污染物一旦埋在沉积物中，可持续数十年，对人类健康和水生生态系统构成严重的长期威胁。麦克马斯特大学的研究员博伊斯和他的研究生们正在通过开发基于磁性的污染沉积物测绘新方法来协助修复工作。他们在安大略湖的初步工作表明，有毒沉积物往往比清洁沉积物具有更高的磁化强度，可以通过在湖床上方拖曳一种称为磁力计的磁感应装置来识别和绘制地图。测量沉积物芯样的磁化强度还可以提供污染物水平的快速“替代”测量，而不需要昂贵和耗时的化学测试。现在需要进一步开展工作，以开发用于污染监测的磁性方法。在NSERC的支持下，博伊斯和他的团队计划调查磁性颗粒和污染物是如何被输送到湖泊盆地的，并开发新的方法来识别污染源的“磁性指纹”。这项研究将导致一种更迅速和有效的方法来绘制湖泊中的污染物，并将加速正在进行的国际努力，以补救五大湖内几个污染严重的AOC的沉积物。

The remediation of contaminated sediments in the Great Lakes is recognized by Canadian and US regulatory agencies as an urgent environmental priority. 42 Areas of Concern (AOC's) have been identified where lake-bottom sediments are contaminated to toxic levels by heavy metals, hydrocarbons and a range of other environmental pollutants. Once buried in sediments, these contaminants can persist for many decades and pose a serious long-term threat to human health and aquatic ecosystems. McMaster researcher Boyce and his graduate students are assisting in remediation efforts by developing new methods for mapping contaminated sediments based on their magnetic properties. Their preliminary work in Lake Ontario has shown that toxic sediments are often more highly magnetized than clean sediments and can be identified and mapped by towing a magnetic sensing device called a magnetometer above the lakebed. Measurement of the magnetization of sediment core samples can also provide rapid 'proxy' measurements of pollutant levels without the need for expensive and time-consuming chemical testing. Further work is now required to develop magnetic methods for pollution monitoring. With NSERC's support, Boyce and his team plan to investigate how magnetic particles and contaminants are transported into lake basins and to develop new methods for 'magnetic finger-printing' of pollution sources. The research will lead to a more rapid and effective approach for mapping contaminants in lakes and will accelerate ongoing international efforts to remediate sediments in several heavily polluted AOC's within the Great Lakes.