Denitrification Potential in Lake Sediment Increases Across a Gradient of Catchment Agriculture |
| |
Authors: | Denise A Bruesewitz David P Hamilton Louis A Schipper |
| |
Institution: | (1) Centre for Biodiversity and Ecology Research, Department of Biological Sciences, The University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand;(2) Department of Earth and Ocean Sciences, The University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand |
| |
Abstract: | Intensification of catchment agriculture has increased nutrient loads and accelerated eutrophication in some lakes, often
resulting in episodic harmful algal blooms or prolonged periods of anoxia. The influence of catchment agriculture on lake
sediment denitrification capacity as a nitrogen (N) removal mechanism in lakes is largely unknown, particularly in contrast
to research on denitrification in agricultural streams and rivers. We measured denitrification enzyme activity (DEA) to assess
sediment denitrification potential in seven monomictic and three polymictic lakes that range in the proportion of agriculture
in the catchment from 3 to 96% to determine if there is a link between agricultural land use in the lake catchment and sediment
denitrification potential. We collected sediment cores for DEA measurements over 3 weeks in austral spring 2008 (October–November).
Lake Okaro, with 96% catchment agriculture, had approximately 15 times higher DEA than Lake Tikitapu, with 3% catchment agriculture
(232.2 ± 55.9 vs. 15.9 ± 4.5 μg N gAFDM−1 h−1, respectively). Additionally, sediment denitrification potential increased with the proportion of catchment in agriculture
(R
2 = 0.85, P < 0.001). Our data suggest that lakes retain a high capacity to remove excess N via denitrification under increasing N loads
from higher proportions of catchment agriculture. However, evidence from the literature suggests that despite a high capacity
for denitrification and longer water residence times, lakes with high N loads will still remove a smaller proportion of their
N load. Lakes have a denitrification potential that reflects the condition of the lake catchment, but more measurements of
in situ denitrification rates across lake catchments is necessary to determine if this capacity translates to high N removal
rates. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|