Collaborative Research: Interaction of Saline-Formation Water, Near-Surface Ground Water, and Large Lakes

最近，安大略湖发现了9317244个长时间的咸水地下水渗入。虽然稳定同位素和地球化学分析表明，咸水地下水来自区域咸水地层水，但地层水的来源并没有得到很好的约束。地球化学和同位素证据表明，休伦湖萨吉诺湾水体中的高氯值可能部分是由于密歇根盆地咸水地层水直接向海湾排放的咸水造成的。由于萨吉诺湾地区的水源和水文地质条件比安大略湖更受限制，因此萨吉诺湾是研究咸水-地层水、近地表地下水和大型湖泊相互作用的绝佳地点。这项研究的目的是：1)通过地球化学和同位素测定记录萨吉诺湾沉积物中咸水的赋存状态和来源；2通过比较海湾孔隙水和地下水的空间等化学趋势，将海湾沉积物中咸水的赋存状态与周围的地下水化学联系起来；以及3通过化学模拟确定咸水对孔隙水化学的影响。这将通过检查萨吉诺湾沉积物和进入海湾的主要分水岭的溪水中的孔隙水的地球化学和同位素特征来实现。将在区域和当地地下水系统的水文地球化学背景下研究这些数据。这项研究的结果将对理解直接向大型湖泊排放地下水的重要性以及大型湖泊与区域地下水流动的相互作用，特别是涉及深层咸水地层水的流动部分，具有重要意义。***

9317244 Long Saline ground-water seeps have been recently found entering Lake Ontario. Although stable isotope and geochemical analyses indicate that the saline ground water is from regional saline formation water, the source for the formation water is not well constrained. Geochemical and isotopic evidence indicates that high Cl values in the water of Saginaw Bay, Lake Huron may be in part caused by the direct discharge to the bay of saline ground water from saline formation water from the Michigan basin. Since the source and hydrogeology of the Saginaw Bay area is better constrained than in Lake Ontario, Saginaw Bay is an excellent site to study the interaction of saline-formation water, near-surface ground water, and large lakes. The objectives of this research are to 1) document the occurrence and source of saline water in the sediments of Saginaw Bay by geochemical and isotopic determinations; (2) relate the occurrence of the saline water in the bay sediments to the surrounding ground-water chemistry by comparing spatial iso- chemical trends in the pore waters of the bay with that of the ground water; and (3) determine the effect of the saline water on pore-water chemistry by chemical modeling. This will be accomplished by examining geochemical and isotopic characteristics of pore water in sediments of Saginaw Bay and in water of the streams in the major watershed entering the bay. The data will be studied in the context of the hydrogeochemistry of the regional as well as local ground-water systems. Results from this study will be important in understanding the importance of direct ground-water discharge to large lakes and the interaction of large lakes and regional ground-water flow particularly that part of the flow that involves deep saline formation water. ***