DOI: 10.5194/hess-23-3503-2019
论文题名: Trajectories of nitrate input and output in three nested catchments along a land use gradient
作者: Ehrhardt S. ; Kumar R. ; Fleckenstein J.H. ; Attinger S. ; Musolff A.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2019
卷: 23, 期: 9 起始页码: 3503
结束页码: 3524
语种: 英语
Scopus关键词: Agriculture
; Biogeochemistry
; Budget control
; Catchments
; Denitrification
; Groundwater
; Land use
; Nitrates
; Runoff
; Soils
; Trajectories
; Travel time
; Wetlands
; Agricultural intensification
; Agricultural land use
; Controlling parameters
; Data-driven approach
; Long-term observations
; Long-term trajectories
; Nitrate concentration
; Travel time distributions
; Soil pollution
英文摘要: Increased anthropogenic inputs of nitrogen (N) to the biosphere during the last few decades have resulted in increased groundwater and surface water concentrations of N (primarily as nitrate), posing a global problem. Although measures have been implemented to reduce N inputs, they have not always led to decreasing riverine nitrate concentrations and loads. This limited response to the measures can either be caused by the accumulation of organic N in the soils (biogeochemical legacy)-or by long travel times (TTs) of inorganic N to the streams (hydrological legacy). Here, we compare atmospheric and agricultural N inputs with longterm observations (1970-2016) of riverine nitrate concentrations and loads in a central German mesoscale catchment with three nested subcatchments of increasing agricultural land use. Based on a data-driven approach, we assess jointly the N budget and the effective TTs of N through the soil and groundwater compartments. In combination with long-term trajectories of the C-Q relationships, we evaluate the potential for and the characteristics of an N legacy. We show that in the 40-year-long observation period, the catchment (270 km2) with 60% agricultural area received an N input of 53 437 t, while it exported 6592 t, indicating an overall retention of 88 %. Removal of N by denitrification could not sufficiently explain this imbalance. Log-normal travel time distributions (TTDs) that link the N input history to the riverine export differed seasonally, with modes spanning 7-22 years and the mean TTs being systematically shorter during the high-flow season as compared to low-flow conditions. Systematic shifts in the C-Q relationships were noticed over time that could be attributed to strong changes in N inputs resulting from agricultural intensification before 1989, the break-down of East German agriculture after 1989 and the seasonal differences in TTs. A chemostatic export regime of nitrate was only found after several years of stabilized N inputs. The changes in C-Q relationships suggest a dominance of the hydrological N legacy over the biogeochemical N fixation in the soils, as we expected to observe a stronger and even increasing dampening of the riverine N concentrations after sustained high N inputs. Our analyses reveal an imbalance between N input and output, long timelags and a lack of significant denitrification in the catchment. All these suggest that catchment management needs to address both a longer-term reduction of N inputs and shorterterm mitigation of today's high N loads. The latter may be covered by interventions triggering denitrification, such as hedgerows around agricultural fields, riparian buffers zones or constructed wetlands. Further joint analyses of N budgets and TTs covering a higher variety of catchments will provide a deeper insight into N trajectories and their controlling parameters. © Author(s) 2019. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/162910
Appears in Collections: 气候变化与战略
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作者单位: Ehrhardt, S., Department of Hydrogeology, Helmholtz-Centre for Environmental Research, Leipzig, 04318, Germany; Kumar, R., Department Computational Hydrosystems, Helmholtz-Centre for Environmental Research, Leipzig, 04318, Germany; Fleckenstein, J.H., Department of Hydrogeology, Helmholtz-Centre for Environmental Research, Leipzig, 04318, Germany, Bayreuth Center of Ecology and Environmental Research, University of Bayreuth, Bayreuth, 95440, Germany; Attinger, S., Department Computational Hydrosystems, Helmholtz-Centre for Environmental Research, Leipzig, 04318, Germany; Musolff, A., Department of Hydrogeology, Helmholtz-Centre for Environmental Research, Leipzig, 04318, Germany
Recommended Citation:
Ehrhardt S.,Kumar R.,Fleckenstein J.H.,et al. Trajectories of nitrate input and output in three nested catchments along a land use gradient[J]. Hydrology and Earth System Sciences,2019-01-01,23(9)