LTREB: Emergent Landscape Patterns in Stream Ecosystem Processes Resulting from Groundwater/Surface Water Interactions

这项研究的总体科学目标是了解通过流域间转移(即从直接分水岭之外)供应给河流的地下水如何影响热带河流的长期功能(25年)。该项目的总部设在哥斯达黎加的低地，那里富含溶质的地下水占旱季河流排放量的一半以上。这些地下水天然富含磷(P)等营养物质，其水平高于污水处理厂下面通常发现的水平。先前的研究表明，河流化学中的景观格局(由溶质丰富的地下水输入的变化引起)反映了初级生产和分解的速度。该项目继续建立关于溪流溶质化学的长期(1988年至今)数据集，这是中美洲低地原始热带雨林的唯一数据集。研究人员正在将河流化学的长期趋势与大规模气候现象联系起来：富含溶质的地下水(也富含碳酸氢盐)缓冲了在与厄尔尼诺相关的干旱之后的一段时间内接收的溪流的酸度增加，而那些没有获得富含溶质的地下水的溪流的酸度急剧增加。该项目的一个结果是开发了一个环境推广计划，重点关注热带地区的水质和数量问题。

The overall scientific objective of this study is to understand how groundwater, supplied to rivers via inter-basin transfers (i.e., from outside the immediate watershed), affects how tropical streams function in the long term (25 yrs). The project is based in lowland Costa Rica, where solute-rich groundwater account for over half of stream discharge in the dry season. This groundwater is naturally-rich in nutrients such as phosphorus (P), with levels higher than those typically found below sewage treatment plants. Prior research has shown that landscape patterns in stream chemistry (resulting from variation in solute-rich groundwater inputs) reflect rates of primary production and decomposition. This project continues to build a long-term (1988-present) data set on stream solute chemistry, which is the only one for lowland primary rainforests of Central America. The investigators are relating long-term trends in stream chemistry to large-scale climatic phenomena: solute-rich groundwater (also rich in bicarbonates) buffer receiving streams against increases in acidity during periods following El Nino-related droughts, while those streams that do not receive solute-rich groundwater experience dramatic increases in acidity. An outgrowth of the project is the development of an environmental outreach program that focuses on water quality and quantity issues in tropical regions.