Partial nitrification enhances natural attenuation of nitrogen in a septic system plume

Reactive and Mixing Processes Governing Ammonium and Nitrate Coexistence in a Polluted Coastal Aquifer

“…Considering the upgradient area and taking into account that NH 4 + fertilizers range between −7.4 and +6.6% [40] [40,44]. The effect of partial nitrification on the isotopic composition of the NH 4 + was also observed in the shallow part of a septic system plume [8]. The other process that can isotopically enrich NH 4 + is annamox [13,41], but, unfortunately, the isotope data for NO 3 − , which could also provide evidence about the role of anammox in NH 4 + transformation in one of the source zones, are not available at UG1.…”

“…Nitrate (NO 3 − ) and ammonium (NH 4 + ) are often recognised as major contaminants in both surface water and groundwater [1][2][3]. The causes can be multiple, including fertilizers leaching in agricultural environments [4][5][6][7], storm and sewage water spillages in urban environments [8][9][10], natural elevated background concentrations [11,12] and spillages of complex chemical mixtures below industrial plants [13,14]. Moreover, the nitrification of NH 4 + into NO 3 − in oxic environments often leads to an increased NO 3 − concentration along the flow paths, up to values well beyond to the maximum water quality admissible levels [15].…”

“…Data from UG2, DG1, DG4 and DG5 monitoring wells show that NO 3 − in the aquifer is affected by different degrees of denitrification. The enriched δ 15 N pattern in residual NO 3 − cannot rule out anammox also being involved in degradation processes at the site [8,19,42]. NH 4 + also shows extremely variable δ 15 N-NH 4 + values, ranging from −4.9 to +14.9% ( Table 1).…”

“…The high NH4 + concentration observed at DG5 is comparable to the high concentration observed in UG1 in the source zone. These depleted δ 15 N-NH4 + values cannot represent sewage nitrogen since this nitrogen is characterised by δ 15 N values between +4.0 and +6.0% [8]. This type of δ 15 N-NH4 + value is characteristic of NH4 + fertilizers and could be part of an old plume that was already present before the installation of the pump and treat system about 20 years ago.…”

Bioelectrochemical Systems for Groundwater Remediation: The Development Trend and Research Front Revealed by Bibliometric Analysis

“…However, great concern has been raised about the deterioration of groundwater quality related to rapid industrialization and civilization in the last decades [2,[6][7][8][9], and groundwater pollution events caused by human activities (the application of fertilizer and manure [10][11][12][13], the discharge of industrial effluents [14][15][16][17][18], and the leakage of landfill sites [19,20] have been reported round the world. Thus, the invention and implementation of groundwater remedial technologies is a hotspot issue for environmental experts nowadays [21][22][23][24], and numerous technologies involving physical, chemical, physical-chemical, biological and biochemical aspects have been invented and applied [25,26], e.g., the pump and treat method (contaminated groundwater is pumped by abstracted wells and further treated) [27][28][29][30], permeable reactive barriers (a subsurface barrier is constructed by reactive materials, and the polluted groundwater is remediated during flowing through the barrier) [31][32][33][34][35], soil vapor extraction (a vacuum is applied to the vadose zone to induce the controlled flow of air and remove volatile and some semi-volatile organic contaminants) [36][37][38], and monitored natural attenuation (based on efficient monitoring, pollutants are degraded to acceptable levels by natural physical, chemical and biochemical reactions) [39][40][41].…”