• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.74-81
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• 2021

A simple and efficient scheme is presented that attempts to implement the site-specific denitrification rate in the reactive transport modeling for the nitrate in groundwater. A series of correlation analyses were conducted using 133 datasets obtained from different nitrate-contaminated sites to find the empirical relationships between denitrification rates and various subsurface properties. Based on Pearson's correlation analysis, the soil organic carbon concentrations showed a statistically significant correlation (r = 0.75, p < 0.05) with the denitrification rates. A linear regression was performed, which could be utilized to effectively determine the site-specific denitrification rate based on the soil organic carbon concentration of a site. The proposed method is expected to effectively replace the conventional methods which either were too complicated for practical application or impose large uncertainties that might end up with unreliable results.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.1
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• pp.94-98
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• 1985

A laboratory experiment was conducted to find out the denitrification rate upon the different levels of nitrogen fertilizer in submerged sandy soil. The results obtained were summarized as follows: 1. The highest denitrification rate was observed at 25 days after incubation. The amount was reached at 1830 ug/100g soil for 20mg nitrogen was applied in 100g soil. 2. Increases of fertilizer nitrogen was enhanced the rate of ammonification and nitrification during the incubation time. 3. Deep correlation was observed between the denitrification capacities which was determined as nitrous oxide and Mitchaelis-Menten kinetic with relation to nitrate concentration. More higher denitrification rates were observed in Mitchaelis-Menten kinetic than dentrification rate with determined as nitrous oxide. 4. A Zero order (with relation to nitrate concentration) kinetic model for denitrification was presented in this experiment condition to illustrate the variability of nitrous oxide concentrations in the submerged soil atmosphere.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.80-89
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• 2015

Nitrate is on the most seriou pollutant encountered in shallow groundwater aquifer in agricultural area. There are various remediation technologies such as ion exchange, reverse osmosis, and biological denitrification to recover from nitrate contamination. Biological denitrification by indigenous microorganism of the technologies has been reviewed and applied on nitrate contaminated groundwater. In this work, we selected the site where the annual nitrate (NO₃⁻) concentration is over 105 mg/L and evaluated denitrification process with sampled soil and groundwater from 3 monitoring wells (MW4, 5, 6). In the results, the nitrate degradation rate in each well (MW 4, 5, and 6) was 25 NO₃⁻ mg/L/day, 6 NO₃⁻ mg/L/day, and 3.4 NO₃⁻ mg/L/day, respectively. Nitrate degradation rate was higher in batch system treated with 2 times higher fumarate as carbon source than control batch system (0.42M fumrate/1M NO₃⁻), comparing with batch system with soil sample. This result indicates that increase of carbon source is more efficient to enhance denitrification rate than addition of soil sample to increase microbial dynamics. In this work, we also confirmed that monitoring method of functional genes (nirK and nosZ) involved in denitrification process can be applied to evaluated denitrifcation process possibility before application of field process such as in-situ denitrification by push-pull test.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.20-24
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• 2012

Denitrification rate was determined for various freshwater wetland types in the Mississippi River Coastal delta plain. Site 1 and 4 were collected from forested-tupelo dominated wetland, and site 2 and 3 were from floating emergent marsh. The maximum $N_2O$ emission was $7.47mg\;N\;m^{-2}$ for site 1 at day 6 after the addition of nitrate, $6.96mg\;N\;m^{-2}$ for site 2 at day 4, $6.63mg\;N\;m^{-2}$ for site 3 at day 3, and $9.64mg\;N\;m^{-2}$ for site 4 at day 4. The denitrification rate was determined using the acetylene inhibition method $1.24mg\;N\;m^{-2}d^{-1}$ for site 1, $1.93mg\;N\;m^{-2}d^{-1}$ for site 2, $2.24mg\;N\;m^{-2}d^{-1}$ for site 3, and $2.78mg\;N\;m^{-2}d^{-1}$ for site 4. The maximum denitrification rate was in the order of site 4 > site 3 > site 2 > site 1.

• Journal of Environmental Science International
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• v.13 no.9
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• pp.779-878
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• 2004

This study was conducted to analyze the operating conditions of predenitrification process to improve the treatment efficiency in low organic loading sewage plant in use today, and to investigate the treatment efficiency of pilot plant added night soil as well as the nitrogen removal characteristics of pilot plant added carbon sources. In the operation under the condition of $BOD_{5}$ sludge load 0.03-0.28kg $BOD_{5}$/kg VSS/d and oxic ammoniac nitrogen sludge load 0.02-0.24 $kgNH_{4}^{+}$-N/kg MLVSS/d, nitrification efficiency is higher than 95%. In order to achieve 70% nitrogen removal at the T-N sludge loading 0.06kg T-N/kg VSSㆍd and the SRT 6～11 days, optimum operating factors were revealed to $CODc_{r}$/T-N ratio 9, recycle ratio 2.6, and denitrification volume ratio 0.33. At this time, denitrification capacity was approximately 0.09 kg $NO_{3}^{-}$-N/kg $CODc_{r}$; specific nitrification rate was 3.4mg $NH_{4}^{+}$-N/g MLVSS/hr; and specific denitrification rate was 4.8mg $NO_{3}^{-}$-N/g MLVSS/hr.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.76-82
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• 1986

A laboratory experiment was conducted to find out the denitrification rate upon the levels of nitrogen and source of organic matter in submerged sandy and sandy loam soil. The results obtained were sumarized as follows; 1. Evolution of nitrous oxide was increased at 1st and 10 days after incubation. And dinitrogen was increased at 1st and 30 days after incubation. Applications of green manure was enhanced the evolution of nitrous oxide ($N_2O$) and dinitrogen ($N_2$). 2. The cumulative denitrification rates at 50 days was high in Gyuam sandy loam soil (O-M: 1.52%) than that of Hamchang sandy soil (O-M: 3.81%). On the other hand, the cumulative emission of dinitrogen was high in Gyuam sandy loam soil while nitrous oxide was high in Hamchang sandy soil. The total mount of denitrification rate was high in order of green manure > rice straw > compost > control soil. 3. Increases of fertilizer nitrogen was enhanced the rate of emission of dinitrogen and nitrous oxide during the incubation time. 4. According to Michaelis-Menten kinetic equation, denitrification rates and reaction efficiency were remarkably increased by application of readily decomposable organic matter with in higher organic matter content of soil. 5. The negative relationship was observed between the evolution of dinitrogen and carbon ($CO_2+CH_4$) while the nitrous oxide with carbon was positive. 6. Under the this experiment conditions 1 mg of carbon was required for production of 4 mg N as $N_2O$ and 3 mg of N as $N_2$, respectively.

• Journal of Soil and Groundwater Environment
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• v.25 no.2_spc
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• pp.16-27
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• 2020

Nitrate contamination has received much attention at local as well as regional scales. The domestic situation is not out of exception, and it has been reported to be very serious, particularly within agricultural areas as a result of excessive usage of nitrogen fertilizers. Meanwhile, nitrate can be naturally attenuated by denitrification in subsurface environments. The denitrification occurs through biotic (biological) and abiotic processes, and numerous previous studies preferentially focused the former. However, abiotic denitrification seems to be significant in specific environments. For this reason, this study reviewed the previous studies that focused on abiotic denitrification processes. Firstly, the current status of nitrate contamination in global and domestic scales is presented, and then the effect of geological media on denitrification is discussed while emphasizing the significance of abiotic processes. Finally, the implications of the literature review are presented, along with future research directions that warrant further investigations. The results of previous studies demonstrated that several geological agents could play a vital role in reducing nitrate. Iron-containing minerals such as pyrite, green rust, magnetite, and dissolved ferrous ion are known to be powerful electron donors triggering denitrification. In particular, it was proven that the rate of denitrification by green rust was comparative to that of biological denitrification. The results indicate that abiotic denitrification should be taken into account for more accurate evaluation of denitrification in subsurface environments.

• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.70-73
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• 2003

Nitrate contamination in the aquatic systems is the primary indicator of poor agricultural management. The influence of sewage sludge application rates (0, 10, 25, 50 and 100 dry Mg/ha) on distribution of nitrate originating from the sewage sludge in soil profiles was investigated. Soil profile monitoring of nitrate was carried out with a Lakeland clay soil in 1997. Irrespectively of the sewage sludge application rates up to 50 dry Mg/ha, the concentration of $NO_3$-N at the 120 cm depth was below 10 mg/kg and the difference due to the amount of sewage sludge application was negligible at this depth. There was virtually no $NO_3$-N below 120 cm depth and this was confirmed by a deep sampling up to 300 cm depth. Most of the nitrate remained in the surface 60 cm of the soil. Below 120 cm depth nitrate concentration was very low because of the denitrification even at high sewage sludge rate of 100 dry Mg/ha. The $NO_3$-N concentrations in the soil fluctuated over the growing season due to plant uptake and denitrification. The risk of groundwater contamination by nitrate from sewage sludge application up to high rate of 100 dry Mg/ha was very low in a wheat grown clay soil with high water table ( < 3 m).

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.172-178
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• 2018

BACKGROUND: Composted animal manure applied to the arable soil for improving soil quality and enhancing crop productivity causes greenhouse gas emissions such as nitrous oxide ($N_2O$) by processes of nitrification and denitrification. However, little studies have been conducted on determining effect of application ratio of composted animal manure on $N_2O$ emission rate and its annual emission pattern from upland soil in South Korea. Therefore, this study was conducted to determine $N_2O$ emission rate and its annual emission pattern from upland soil supporting for sweet potato. METHODS AND RESULTS: Composted animal manure was applied at the ratio of 0, 10, and 20 Mg/ha to an upland soil supporting for sweet potato (Ipomoea batatas). Nitrous oxide emission was examined during growing season and non-growing season from May 2016 through May 2017. Daily $N_2O$ fluxes showed peaks right after applications of composted animal manure and inorganic nitrogen fertilizer. Precipitation and soil water content affected daily $N_2O$ flux during non-growing season. Especially, $N_2O$ flux was strongly associated with water filled pore space (WFPS). We assumed that the majority of $N_2O$ measured during growing season of sweet potato was produced from nitrification and subsequent denitrification. Annual cumulative $N_2O$ emission rate significantly increased with increasing application ratio of composted animal manure. It increased to 12.0 kg/ha/yr from 8.73 kg/ha/yr at control with 10 Mg/ha of composted animal manure and to 14.0 kg/ha/yr of $N_2O$ emission with 20 Mg/ha of the manure. CONCLUSION: To reduce $N_2O$ emission from arable soil, further research on developing management strategy associated with use of the composted animal manure and soil moisture is needed.

• Journal of Soil and Groundwater Environment
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• v.24 no.4
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• pp.1-10
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• 2019

Recently, groundwater contamination by mixed occurrence of arsenic (As) and nitrate ($NO_3{^-}$) has been a serious environmental issue all around world. In this study, we investigated the microbial As(III) oxidation characteristic under denitrification process to examine the feasibility of the microbial consortia in wetland sediment to simultaneously treat these two contaminants. The detail objectives of this study were to investigate the effects of $NO_3{^-}$ on the oxidation of As(III) in anaerobic environments and observe the microbial community change during the As oxidation under denitrification process. Results showed that the As(III) was completely and simultaneously oxidized to As(V) under denitrification process, however, it occurred to a much less extent in the absence of sediment or $NO_3{^-}$. In addition, the significant increase of As(III) oxidation rate in the presence of $NO_3{^-}$ suggested the potential of As oxidation under denitrification by indigenous microorganisms in wetland sediment. Genera Pseudogulbenkiania, and Flavisolibacter were identified as predominant microbial species driving the redox process. Conclusively, this study can provide useful information on As(III) oxidation under denitrifying environment and contribute to develop an effective technology for simultaneous removal of As(III) and $NO_3{^-}$ in groundwater.