Rapid nitrate loss from a contaminated desert soil

McKeon, C.; Jordan, Fiona L.; Glenn, Edward P.; Waugh, W. Joseph; Nelson, Steven G.

doi:10.1016/j.jaridenv.2004.08.006

Cited by 24 publications

(26 citation statements)

References 22 publications

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“…Furthermore, McKeon et al (2005) do describe one case of surprisingly rapid denitrification. It is possible that a combination of the subsurface conditions, together with the extended residence time, as the contaminants have travelled further from the soakaway, has facilitated the denitrification process.…”

Section: Nitrogenmentioning

confidence: 99%

Movement of contaminants in the unsaturated zone of the subsurface from a low flush on-site sanitation system in Ivory Park, Johannesburg

Ryneveld

Fourie

Palmer³

2016

WSA

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This study measured the movement of contaminants in the unsaturated zone of the subsurface from a low-flush on-site sanitation system (also known as an aqua-privy) at three sites in Ivory Park, which at the time that the fieldwork was done was a newly-established informal settlement in Johannesburg. The aim of the study was to provide field data on the movement of contaminants from this sanitation system in a low-income area, in these climatic and subsurface conditions, and to counter a perception that on-site sanitation will inevitably cause pollution. Subsurface conditions consisted nominally of a 1 m thick layer of silty sand with denser gravel at the bottom of it, underlain by a stiff sandy clay (residual granite), with the natural water table more than 15 m below ground surface. In summary, it can be deduced that movement in the unsaturated zone of bacterial indicators, nitrogen and phosphorus from low-flush on-site sanitation systems in lowincome areas is very limited, as long as the effluent remains in the subsurface. More specifically, the impact in terms of COD appears to be negligible, with substantial treatment apparently taking place within the soakaway or within the immediate vicinity thereof. With respect to (i) bacteriological indicators, (ii) nitrogen (in the form of ammonium, nitrite and nitrate) and (iii) phosphorus (in the form of Total Phosphorus), using the distilled water washout technique, there is a very rapid drop-off of contamination with distance from the soakaway. At horizontal distances of 3 m from the soakaway, levels of the measured contaminants had dropped to values consistent with the background levels. The results of this study are not confined to this particular sanitation system. By virtue of the higher hydraulic loading, these results provide an upper bound for contaminant movement from dry on-site systems under similar conditions.

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Section: Nitrogenmentioning

confidence: 99%

Movement of contaminants in the unsaturated zone of the subsurface from a low flush on-site sanitation system in Ivory Park, Johannesburg

Ryneveld

Fourie

Palmer³

2016

WSA

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“…This surface remediation initiative was completed in 1994. Since this time, several phytoremediation studies have been performed within the former source zone to limit the transport of nitrate from the shallow alluvial material to the aquifer and remove nitrate from the groundwater using deeprooting indigenous plants (McKeon et al 2005;McKeon et al 2006). Laboratory microcosm studies were conducted using sediments from the site to evaluate the impact of ethanol amendments on denitrification (Jordan et al 2008;Carroll et al 2009).…”

Section: Site Descriptionmentioning

confidence: 99%

Ethanol Addition for Enhancing Denitrification at the Uranium Mill Tailing Site in Monument Valley, AZ

Borden

Brusseau

Carroll

et al. 2011

Water Air Soil Pollut

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Past mining and processing of uranium ore at a former uranium mining site near Monument Valley, AZ has resulted in nitrate contamination of groundwater. The objective of this study was to investigate the potential of ethanol addition for enhancing the reduction of nitrate in groundwater. The results of two pilot-scale field tests showed that the concentration of nitrate decreased, while the concentration of nitrous oxide (a product of denitrification) increased. In addition, changes in aqueous concentrations of sulfate, iron, and manganese indicated that the ethanol amendment caused a change in prevailing redox conditions. The results of compound-specific stable isotope analysis for nitrate-nitrogen indicated that the nitrate concentration reductions were biologically mediated. Denitrification rate coefficients estimated for the pilot tests were approximately 50 times larger than resident-condition (non-enhanced) values obtained from prior characterization studies conducted at the site. The nitrate concentrations in the injection zone have remained at levels three orders of magnitude below the initial values for many months, indicating that the ethanol amendments had a long-term impact on the local subsurface environment.

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“…Site characteristics and previous research are reported in McKeon et al (2005McKeon et al ( , 2006; Jordan et al (2008), and in documents from the United States Department of Energy (1999,2000,2004,2006). Annual precipitation is approximately 110 mm, arriving as summer monsoon rains and winter snow and rain.…”

Section: Site Descriptionmentioning

confidence: 99%

“…Standing dry biomass was estimated from canopy area projected on the ground from a sample of 20 ATCA plants of varying sizes, for which canopy area and dry biomass were both determined (Figure 2(B)) (McKeon et al, 2005).…”

Section: Determining F C and Standing Biomass From Quickbird Imagesmentioning

confidence: 99%

Scaling sap flux measurements of grazed and ungrazed shrub communities with fine and coarse‐resolution remote sensing

et al. 2008

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Rapid nitrate loss from a contaminated desert soil

Cited by 24 publications

References 22 publications

Movement of contaminants in the unsaturated zone of the subsurface from a low flush on-site sanitation system in Ivory Park, Johannesburg

Movement of contaminants in the unsaturated zone of the subsurface from a low flush on-site sanitation system in Ivory Park, Johannesburg

Ethanol Addition for Enhancing Denitrification at the Uranium Mill Tailing Site in Monument Valley, AZ

Scaling sap flux measurements of grazed and ungrazed shrub communities with fine and coarse‐resolution remote sensing

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