 |
| Titel |
Tracing runoff- and erosion-driven transport of slurry-derived pollutants in soil systems using molecular-scale organic biomarkers |
| VerfasserIn |
Charlotte Lloyd, Katerina Michaelides, Richard Evershed, David Chadwick, Jennifer Dungait |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053185
|
|
|
|
|
|
| Zusammenfassung |
| Understanding how cattle slurry is partitioned and transported through a soil system via
different pathways is extremely important given that in the EU alone ca. 1 billion tonnes of
dung and slurry are produced annually, and recycled by applying to land. Much research has
highlighted the potential for contamination caused by slurry application, for example
ammonium and nitrate leaching and the transport of pathogens such as E. coli. However,
further research is required to determine the timing and extent of contamination as influenced
by hillslope topography and hydrology. To achieve this, organic and inorganic biomarkers
were used to investigate the transport in soil-water systems of potential pollutants
deriving from additions of cattle slurry to land. This biomarker approach allows
differentiation of pollutants transported through sediment-bound and dissolved
pathways.
A series of experiments were carried out using University of Bristol’s TRACE
experimental facility. The dual axis soil slope (6 Ã 2.5 Ã 0.3 m3) accompanied by a 6-nozzle
rainfall simulator, enables manipulation of the slope to simulate different topographic
and rainfall scenarios. Cattle slurry was applied to the top of the experimental soil
slope at a rate of 5 L m-2 and rainfall simulations were carried out, where the
slope gradient (5Ë and 10Ë ) and the rainfall intensity (60 and 120 mm h-1) were
varied. A no-slurry treatment acted as the experimental control. During each rainfall
simulation, samples of water were collected via outlets below the slope and spatial soil
cores were taken from the slope after each experiment. Ammonium, nitrate and
protein fluorescence were monitored in the water samples to investigate the fate of
dissolved components of slurry through different hydrological pathways: surface runoff,
sub-surface through-flow and vertical percolated flows. In addition, lipid biomarkers
5β-stigmastanol and 5β-epistigmastanol (5β-stanols) were quantified in the soil
cores and used to trace the transport of sediment-bound pollutants from the slurry.
These faecal waste-specific biomarkers, determined using GC/MS, derive from
microbially-mediated biohydogenation of plant sterols in a ruminant gut, providing a
robust method to trace the transport of bovine faecal matter via eroded sediment
pathways.
The results show that contributions of potential pollutants from the surface
and sub-surface flow pathways and from the eroded sediment differ according to
slope gradient and rainfall intensity. Therefore, as the contribution of each of these
pathways changes in response to rainfall and topography, the pollution risk also changes
accordingly as different organic compounds are mobilised at varying rates. Rapid
hydrological response to rainfall results in erosion and transport of sediment-bound and
dissolved pollutants, creating an immediate contamination threat. However, conditions
resulting in a slow hydrological response, while leading to lower erosion rates and
sediment-bound pollutant transport, results in higher rates of dissolved pollutant transport
through the soil layers which poses a threat of contamination of the soil sub-surface. |
|
|
|
|
|
|