Flow and Transport Processes in a Riverine Peat Deposit

湿地内的地下水流状况仅在极少数地区得到了很好的了解，尽管地球表面泥炭覆盖、水饱和的地形具有很大的面积重要性，而且湿地在许多流域具有水文战略地位。生态学家长期以来一直将泥炭地开发的关键方面归因于水文、化学运输和植物生长的相互作用。湿地还可以在有毒化学物质的运输和去向中发挥关键的控制作用。本项目的重点是这样一个湿地，在那里，深层泥炭沉积与一条严重污染的河流和一个冰川喷发含水层相互作用，其中包含一个以前的市政井田。在这一背景下，将研究通过泥炭地的地下水输送的基本过程，重点是泥炭在几个空间尺度上的特征，以及地下水流动和化学输送的过程。一种可行的假设是，由于泥炭形成规模上的不均质性，湿地中水分和污染物的移动速率可能显著超过通常被认为是泥炭形成的低速率。因此，将进行各种测量和测试，以确定和评估这些异质性的重要性。调查技术将包括水头和水力传导性测量、压电式测量、含水层压力/示踪剂测试、土壤和地下水的化学分析，以及某些有毒金属的形态分析和顺序提取。

The subsurface flow regime within wetlands is well understood only in very few locations, despite the large areal importance of peaty, water-saturated terrain on Earth's surface and the hydrologically strategic location of wetlands in many catchments. Ecologists have long attributed key aspects of peatland development to the interactions of hydrology, chemical transport, and plant growth. Wetlands can also play a critical, controlling role in the transport and fate of toxic chemicals. The present project is focused on such a wetland, where a deep peat deposit interacts with both a heavily contaminated river and a glacial outwash aquifer containing a former municipal wellfield. In this setting the fundamental processes of subsurface water transport through a peatland will be studied, with a focus on peat characteristics at several spatial scales and the processes that subsurface water flow and chemical transport. One working hypothesis is that, due to heterogeneity on the scale of the peat formation, rates of both water and pollutant movement through the wetland may significantly exceed the low rates commonly attributed to peat formations. Accordingly, a variety of measurements and tests will be conducted to define and assess the importance of these heterogeneities. Investigative techniques will include head and hydraulic conductivity measurements, a piezocone survey, aquifer stress/tracer tests, chemical analyses of soil and groundwater, and speciation analysis and sequential extractions of certain toxic metals.