Patterns in groundwater nitrogen concentration in the floodplain of a subtropical stream (Wollombi Brook,New South Wales) |
| |
Authors: | Email author" target="_blank">Sébastien?LamontagneEmail author Andrew L?Herczeg John C?Dighton Jaswant S?Jiwan Jodie L?Pritchard |
| |
Institution: | (1) CSIRO Land & Water, PMB 2, 5064 Glen Osmond, South Australia, Australia;(2) New South Wales Department of Infrastructure, Planning and Natural Resources, P.O. Box 3720, 2124 Parramatta, NSW, Australia |
| |
Abstract: | The sources of groundwater and the patterns in groundwater dissolved N and DOC concentration in the floodplain of a subtropical stream (Wollombi Brook, New South Wales) were studied over a 2-year period using three piezometer transects. While the stream was generally a discharge area for regional groundwater, this source represented only a small contribution to either the water or N budget of the alluvial aquifer. Groundwater–surface water interactions appeared mostly driven by cycles of bank recharge and discharge between the stream and the alluvial aquifer. DON and NH4+ were the principal forms of dissolved N in groundwater, consistent with the primarily suboxic to anoxic conditions in the alluvial aquifer. A plume of groundwater NO3− was found at one transect where oxic conditions persisted within the riparian zone. The origin of the NO3− plume was hypothesized to be soil NO3− from the riparian zone flushed to the water table during recharge events. When present, NO3− did not reach surface water because conditions in the alluvial aquifer in the vicinity of the stream were always reduced. The concentration of groundwater DOC was variable across the floodplain and may be related to the extent of the vegetation cover. Overall, transformation and recycling of N during lateral exchange processes, as opposed to discharge of new N inputs from regional groundwater, appears to primarily control N cycling during groundwater–surface water interactions in this subtropical floodplain. |
| |
Keywords: | Floodplain Groundwater Nitrogen Subtropical stream |
本文献已被 SpringerLink 等数据库收录! |
|