气候变化领域集成服务门户(CCPortal): Trajectories of nitrate input and output in three nested catchments along a land use gradient

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DOI	10.5194/hess-23-3503-2019
	Trajectories of nitrate input and output in three nested catchments along a land use gradient
	Ehrhardt S.; Kumar R.; Fleckenstein J.H.; Attinger S.; Musolff A.
发表日期	2019
ISSN	1027-5606
起始页码	3503
结束页码	3524
卷号	23 期号:9
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.
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
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159620
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
推荐引用方式 GB/T 7714	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],2019,23(9).
APA	Ehrhardt S.,Kumar R.,Fleckenstein J.H.,Attinger S.,&Musolff A..(2019).Trajectories of nitrate input and output in three nested catchments along a land use gradient.Hydrology and Earth System Sciences,23(9).
MLA	Ehrhardt S.,et al."Trajectories of nitrate input and output in three nested catchments along a land use gradient".Hydrology and Earth System Sciences 23.9(2019).