Assessment of contaminant loadings in lake sediments using magnetic property measurements

加拿大和美国的监管机构认为，五大湖受污染沉积物的修复是一项紧迫的环境优先事项。已经确定了42个关注区域，其中湖底沉积物被重金属、碳氢化合物和一系列其他环境污染物污染到有毒水平。这些污染物一旦被埋在沉积物中，可持续存在数十年，并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人员博伊斯和他的研究生们正在开发新的方法，根据受污染的沉积物的磁性来绘制它们的地图，从而协助修复工作。他们在安大略湖的初步工作表明，有毒沉积物通常比干净沉积物的磁化程度更高，可以通过在湖床上方拖拽一种称为磁力计的磁感应装置来识别和绘制。测量沉积物岩心样品的磁化强度也可以提供污染物水平的快速“代理”测量，而不需要昂贵和耗时的化学测试。现在需要进一步的工作来发展用于污染监测的磁性方法。在国家科学研究委员会的支持下，博伊斯和他的团队计划研究磁性颗粒和污染物是如何进入湖盆的，并开发污染源的“磁性指纹”新方法。这项研究将为绘制湖泊污染物地图提供一种更快速、更有效的方法，并将加速正在进行的国际努力，以修复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.