Runoff- and erosion-driven transport of cattle slurry: linking molecular tracers to hydrological processes
The addition of cattle slurry to agricultural land is a widespread practise, but if not correctly managed it can pose a contamination risk to aquatic ecosystems. The transport of inorganic and organic components of cattle slurry to watercourses is a major concern, yet little is known about the physi...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-02-01
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Series: | Biogeosciences |
Online Access: | http://www.biogeosciences.net/13/551/2016/bg-13-551-2016.pdf |
Summary: | The addition of cattle slurry to agricultural land is a widespread practise,
but if not correctly managed it can pose a contamination risk to aquatic
ecosystems. The transport of inorganic and organic components of cattle
slurry to watercourses is a major concern, yet little is known about the
physical transport mechanisms and associated fluxes and timings of
contamination threats. Therefore, the aim of the study was to ascertain the
importance of flow pathway partitioning in the transport (fluxes and timing)
of dissolved and particulate slurry-derived compounds with implications for
off-site contamination. A series of rainfall–runoff and erosion experiments
were carried out using the TRACE (Test Rig for Advancing Connectivity
Experiments) experimental hillslope facility. The experiments allowed the
quantification of the impact of changing slope gradient and rainfall
intensity on nutrient transport from cattle slurry applied to the hillslope,
via surface, subsurface, and vertical percolated flow pathways, as well as
particulate transport from erosion. The dissolved components were traced
using a combination of ammonium (NH<sub>4</sub><sup>+</sup>) and fluorescence analysis,
while the particulate fraction was traced using organic biomarkers,
5<i>β</i>-stanols. Results showed that rainfall events which produced flashy
hydrological responses, resulting in large quantities of surface runoff, were
likely to move sediment and also flush dissolved components of slurry-derived
material from the slope, increasing the contamination risk. Rainfall events
which produced slower hydrological responses were dominated by vertical
percolated flows removing less sediment-associated material, but produced
leachate which could contaminate deeper soil layers, and potentially
groundwater, over a more prolonged period. Overall, this research provides
new insights into the partitioning of slurry-derived material when applied to
an unvegetated slope and the transport mechanisms by which contamination
risks are created. |
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ISSN: | 1726-4170 1726-4189 |