Assessment of contaminant loadings in lake sediments using magnetic property measurements

加拿大和美国的监管机构将修复五大湖中受污染的沉积物视为紧迫的环境优先事项。已经确定了42个受关注区域，其中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。一旦被埋在沉积物中，这些污染物可能会持续数十年，并对人类健康和水生生态系统构成严重的长期威胁。麦克马斯特研究人员博伊斯和他的研究生们正在帮助修复工作，他们开发了基于沉积物磁性绘制受污染沉积物地图的新方法。他们在安大略湖的初步工作表明，有毒沉积物的磁化程度往往比清洁沉积物更高，可以通过在湖床上方拖动一种名为磁强计的磁感应设备来识别和绘制地图。测量沉积物岩心样品的磁化强度还可以提供污染物水平的快速“替代”测量，而不需要昂贵且耗时的化学测试。现在需要进一步的工作来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输送到湖盆中的，并开发新的方法来对污染源进行“磁性指纹”识别。这项研究将导致一种更快速、更有效的方法来绘制湖泊中的污染物地图，并将加快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.