Timescales of Geochemical and Isotopic Transport in Natural Waters

一种新的天然水中溶质和同位素运移模型正在改进和测试中。这个模型可以量化交通的时间尺度，而不需要特别的假设，将地下水和地表水成分结合起来。根据扩散理论，风暴事件被视为引发一系列复杂的地球化学和物理反应的“三角洲函数”。输运方程很容易转化为线性形式，其截距准确地追溯了风暴事件的时间，其斜率揭示了每种生物化学成分的输送时间常数。其基本概念是研究具有自然过程提供的扰动的自然系统。关于地表溪流和泉水对风暴事件的地球化学和同位素反应所获得的信息将确定复杂自然反应的时间尺度。本项目第一阶段收集的数据显示，不同的参数(离子浓度、总溶解有机物、营养物质、沉积物、氧同位素等)。有一个定性相似的方式，可以用模型来解释，但在共同定义自然系统响应的参数中，时间尺度差别很大。这一模型的严格测试将使用从未蓄水的河流流域(密苏里州东部的Meramec盆地)内的几个地点收集的地球化学和同位素数据进行。这项工作将由安装在华盛顿大学泰森研究中心岩溶泉水中的自动取样器和附近Meramec河上的新自动取样器来推动。这些可编程设备将允许密集采样以准确地解析时间尺度，并将允许对同时发生的地下水和河流对降水事件的响应进行详细比较。将探讨污染物和病原体在地表和近地表环境中的来源、反应(溶解度、离子交换、吸附、生物吸收等)、迁移途径和时间尺度等关键问题。新的方法似乎适用于不同的地球化学、物理和同位素成分。它具有独特的潜力，可以利用自然事件来解决自然系统的复杂性。

0106925Criss A new model of solute and isotopic transport in natural waters is being refined and tested. This model can quantiy the timescales of transport without ad hoc assumptions, about ixing groundwater and surface water components. Based on diffusion theory, storm events are treated as "delta functions" that induce a complex series of geochemical and physical responses. The transport equations are readily transformed into linear versions whose intercepts accurately retrodict the timing of the storm events, and whose slopes reveal the time constants for transport of each creochemical constituent. The basic concept is to study the natural system with perturbations provided by natural processes. Information gained onthe geochemical and isotopic response of surface streams and springs to storm events would determine the timescales of complex natural responses. Data colllected in the first stage of this project show that different parameters (ionic concentraions, total dissolved organic compounds, nutrients, sediment, oxygen isotopes, etc.) have in a qualitatively similar manner, explicable by the model, but that the timescales vary greatly among the parameters that collectively define the response of the natural system. Rigorous tests of this model will be conducted withgeochemical and isotopic data collected from several sites within an unimpounded river basin (the Meramec Basin, eastem Missouri). This endeavor will be facilitated by an autosamplerinstalled a karst spring at Washington University's Tyson Research Center, and a new autosampler nearby on the Meramec River. These programmable devices will allow intensive sampling to resolve timescales accurately, and will permit detailed comparisons of simultaneous groundwater and riverine responses to precipitation events. Key questions concerning the sources, the reactions (solubility, ion exchange, adsorption, biological uptake, etc.), the migration paths, and the timescales of pollutant and pathogen transport through surface and near-surface environments will be explored. The new approach appears to be applicable to diverse geochemical, physical, and isotopic constituents. It has the unique potential to resolve the complexity of natural systems using natural events.