Rainfall-Driven Amplification of Seasonal Acidification in Poorly Buffered Tropical Streams
Rainfall-Driven Amplification of Seasonal Acidification in Poorly Buffered Tropical Streams
复制标题
降雨驱动的缓冲不良热带溪流季节性酸化放大
DOI：
10.1007/s10021-012-9559-6
复制
发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
C. Pringle
中科院分区：
文献类型：
--
作者：
G. Small;M. Ardón;A. P. Jackman;J. Duff;F. Triska;A. Ramírez;Marcía N. Snyder;C. Pringle
淡水生态系统酸化具有重要的生态和生物地球化学效应。受人为酸化影响的温带河流已被广泛研究，但由于缺乏长期数据集，我们对热带河流自然酸化的理解受到限制。在这里，我们分析了哥斯达黎加低地8条热带河流的13个采样站14年来的每月观测数据。在4个月的旱季，河流pH值呈上升趋势，而在整个雨季则呈下降趋势。季节性pH值下降的幅度在最干燥的旱季之后最大，包括1998年历史上最大的El Niño南方涛动事件，当时一些河流的pH值降至4.0以下。在缓冲能力差的研究溪流中，溶解的二氧化碳导致了较低的基线pH值，我们假设土壤中二氧化碳通过地下流动路径的涌入导致了观测到的季节性pH值下降。我们的研究结果表明，热带地区的降雨、陆地和水生生态系统之间存在紧密耦合。预计热带旱季降雨量的减少可能导致季节性酸化程度的增加。
Acidification in freshwater ecosystems has important ecological and biogeochemical effects. Temperate streams affected by anthropogenic acidification have been extensively studied, but our understanding of natural acidification in tropical streams has been constrained by the lack of long-term datasets. Here, we analyze 14 years of monthly observations from 13 sampling stations in eight tropical streams in lowland Costa Rica. Stream pH increased during the 4-month dry season and declined throughout the wet season. The magnitude of the seasonal pH decline was greatest following the driest dry seasons, including the historically large El Niño Southern Oscillation event in 1998 when pH values dropped below 4.0 in some streams. Dissolved CO2 accounts for the low baseline pH in the poorly buffered study streams, and we hypothesize that an influx of soil-derived CO2 via subsurface flow paths contributes to the observed seasonal pH declines. Our results show tight coupling between rainfall, terrestrial, and aquatic ecosystems in the tropics. Predicted decreases in dry season rainfall for the tropics may lead to an increased magnitude of seasonal acidification.