A study was undertaken on drained and undrained 1 ha grassland lysimeters to assess the effectiveness of multiple novel tracing techniques in understanding how agricultural slurry waste moves from land to water. Artificial fluorescent particles designed to mimic the size and density of organic slurry particles were found to move off the grassland via inter-flow (surface + lateral through-flow) and drain-flow. Where both pathways were present the drains carried the greater number of particles. The results of the natural fluorescence and δ13C of water samples were inconclusive. Natural fluorescence was higher from slurry-amended lysimeters than from zero-slurry lysimeters, however, a fluorescence decay experiment suggested that no slurry signal should be present given the time between slurry application and the onset of drainage. The δ13C values of >0.7 microm and <0.7 microm material in drainage were varied and unrelated to discharge. The mean value of >0.7 microm δ13C in water from the drain-flow pathways was higher from the lysimeter which had received naturally enriched maize slurry compared to the lysimeter which received grass slurry indicating a contribution of slurry-derived material. Values of <0.7 microm δ13C from the same pathway, however, produced counter intuitive trends and may indicate that different fractions of the slurry have different δ13C values.
Evidence for the movement of agricultural slurry and associated pollutants into surface waters is often anecdotal, particularly with relation to its 'particulate' components which receive less attention than 'bio-available' soluble phases. To assess the extent of movement of slurry particles artificial fluorescent particles were mixed with slurry and applied to a field sub-catchment within a headwater catchment. Particles were 2-60 μm in diameter and two different densities, 2.7 and 1.2 g cm(-3) representing 'inorganic' and 'organic' material. Water samples from the field and catchment outlet were collected during two storm events following slurry application and analysed for particle and suspended sediment concentrations (SSC). SSC from the field and catchment outlet always formed clockwise hysteresis loops indicating sediment exhaustion and particles of the two densities were always found to be positively correlated. Particles from the field formed clockwise hysteresis loops during the first discharge event after slurry application, but anti-clockwise hysteresis loops during the second monitored event which indicated a depletion of readily mobilisable particles. Particles from the catchment outlet always formed anticlockwise hysteresis loops. Particle size became finer spatially, between field and catchment outlet, and temporally, between successive storm events. The results indicate that slurry particles may be readily transported within catchments but that different areas may contribute to pollutant loads long after the main peak in SSC has passed. The density of the particles did not appear to have any effect on particle transport however the size of the particles may play a more important role in the 2-60 μm range.
During 2006 to 2009, two sediment tracer studies were implemented at the mouth of the Columbia River (MCR) to improve our understanding of littoral sediment transport pathways along the ocean margins of the inlet. Science-based data from these tracer studies is being integrated with other analysis methods to evaluate if dredged material can be preferentially placed within the coastal near shore to augment the sediment budget of the inlet and adjacent coastal margin. This paper summarizes the MCR tracer study methodology and results, with specific emphasis of how the general limitations for tracer studies were addressed and overcome. Results from these studies conclusively show that tracer particles released along the coastal margin of the MCR (at water depth of 13-14 meters) were transported into the active littoral zone of Oregon and Washington, with tracer deposition occurring on beaches. The results indicate that the sand-sized sediment at MCR is dispersed differently along the northern side of the inlet as compared to the southern side. Report Documentation Page Form Approved OMB No. 0704-0188Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES in ABSTRACT During 2006 to 2009, two sediment tracer studies were implemented at the mouth of the Columbia River (MCR) to improve our understanding of littoral sediment transport pathways along the ocean margins of the inlet. Science-based data from these tracer studies is being integrated with other analysis methods to evaluate if dredged material can be preferentially placed within the coastal near shore to augment the sediment budget of the inlet and adjacent coastal margin. This paper summarizes the MCR tracer study methodology and results, with specific emphasis of how the general limitations for tracer studies were addressed and overcome. Results from these studies conclusively show that tracer particles released along the coastal margin of the MCR (at water depth of 13-14 meters) were transported into the active littoral zone of Oregon and Washington, with tracer deposition occurring on beaches. The results indicate that the sand-sized sediment at MCR is dispersed differently along the northern side of the inlet as compared to the southern side. 15. SUBJECT TERMS 16. SECURITY CLASSIFICA...
This report documents a field data collection program, including the sediment tracer study, and numerical modeling investigation for dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to Coos Bay Inlet, OR. The collected data around the inlet system were assembled, analyzed, and used to calibrate and validate the Coastal Modeling System (CMS) and the Particle Tracking Model (PTM). Sediment transport pathways and fate of placed material were evaluated. The model and sediment tracer study results indicate that the tracer placed within the nearshore ODMDS primarily moves alongshore towards the inlet at the initial stage of the release. Material arriving at the inlet channel and ebb shoal is jettisoned offshore by strong ebb currents. The results also show that the sediment tracer spreads northward alongshore due to strong dominant southerly wind across the inner continental shelf. At and outside the inlet, finer particles are transported the farthest offshore and away from the navigation channel and nearshore ODMDS area. A new sediment mapping technique applied in model simulations demonstrates migration and burial for sediments placed in the nearshore ODMDS. Both CMS and PTM results compare well with those of the sediment tracer study. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.
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