Evaluation of groundwater discharge into small lakes based on the temporal distribution of radon-222

Limnology and Oceanography
By:  and 

Links

Abstract

In order to evaluate groundwater discharge into small lakes we constructed a model that is based on the budget of 222Rn (radon t1/2 5 3.8 d) as a tracer. The main assumptions in our model are that the lake's waters are wellmixed horizontally and vertically; the only significant 222Rn source is via groundwater discharge; and the only losses are due to decay and atmospheric evasion. In order to evaluate the groundwater-derived 222Rn flux, we monitored the 222Rn concentration in lake water over periods long enough (usually 1-3 d) to observe changes likely caused by variations in atmospheric exchange (primarily a function of wind speed and temperature). We then attempt to reproduce the observed record by accounting for decay and atmospheric losses and by estimating the total 222Rn input flux using an iterative approach. Our methodology was tested in two lakes in central Florida: one of which is thought to have significant groundwater inputs (Lake Haines) and another that is known not to have any groundwater inflows but requires daily groundwater augmentation from a deep aquifer (Round Lake). Model results were consistent with independent seepage meter data at both Lake Haines (positive seepage of ??? 1.6 ?? 104 m3 d-1 in Mar 2008) and at Round Lake (no net groundwater seepage). ?? 2011, by the American Society of Limnology and Oceanography, Inc.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Evaluation of groundwater discharge into small lakes based on the temporal distribution of radon-222
Series title Limnology and Oceanography
DOI 10.4319/lo.2011.56.2.0486
Volume 56
Issue 2
Year Published 2011
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Limnology and Oceanography
First page 486
Last page 494