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Soil-stream Interfaces as Control-Points for Speciation and Transformations of Nitrogen in a Heterogeneous Landscape

土壤-流界面作为异质景观中氮的形态和转化的控制点

基本信息

批准号：
9208395
负责人：
Lars Hedin
金额：
$ 9.82万
依托单位：
Michigan State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1992
资助国家：
美国
起止时间：
1992-09-01 至 1995-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9208395&HistoricalAwards=false
关键词：
Soil stream Interfaces Control Points

项目摘要

This project focuses on the role of soil-stream interfaces as control-points for the speciation (NO3-vs. NO2-vs. NH4+vs. DON vs. N2O) and flux of N in a heterogeneous landscape. Biogeochemical transformations of N at the soil-stream interface may have important effects on both the quantity and quality (speciation) of N lost to downstream ecosystems, and may modify the extent to which h the chemistry of watershed streams are affected by watershed processes. A mechanistic understanding of such N transformations along soil-stream flowpaths may therefore be critical in order to predict how watershed disturbances (both short-term and chronic) will affect surface-water chemistry. Preliminary studies from the Augusta Creek Watershed have pointed to soil-stream interfaces as potential control-points for downstream speciation and flux of N. The work outlined in this project seeks to provide an understanding of rates and mechanisms of N transformations along explicit soil-stream hydrologic flowpaths in the watershed. The principal investigators will use both descriptive and experimental approaches, including the use of tracers of hydrologic flowpaths (LiBr) and tracers for specific biogeochemical reactions (stable N isotopes). The main goal is to understand how patterns of N transformations at soil-stream interfaces vary in space, time,and as a function of hydrology.

本项目重点研究土壤-溪流界面作为物种形成（NO3-vs. no3）控制点的作用。NO2-vs。NH4 + vs。DON vs. N2O)和异质景观中N的通量。土壤-河流界面氮的生物地球化学转化可能对下游生态系统损失的氮的数量和质量（形态）产生重要影响，并可能改变流域河流化学受流域过程影响的程度。因此，为了预测流域干扰（短期和长期）将如何影响地表水化学，对沿着土壤流路径的这种N转换的机制理解可能是至关重要的。来自奥古斯塔河流域的初步研究指出，土壤-溪流界面是下游氮形态和通量的潜在控制点。本项目概述的工作旨在提供对流域中明确的土壤-溪流水文流道中N转换的速率和机制的理解。主要研究人员将使用描述性和实验性方法，包括使用水文流动路径示踪剂（LiBr）和特定生物地球化学反应示踪剂（稳定的N同位素）。主要目标是了解土壤-溪流界面的N转换模式如何随空间、时间和水文变化而变化。