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Journal articles on the topic 'Anoxic zones'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 March 2023

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1

de Beer, Dirk, Andreas Schramm, Cecilia M. Santegoeds, and Helle K. Nielsen. "Anaerobic processes in activated sludge." Water Science and Technology 37, no. 4-5 (1998): 605–8. http://dx.doi.org/10.2166/wst.1998.0726.

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We found anoxic zones in aerated activated sludge flocs, and demonstrated denitrification under normal operating conditions. Sulfate reduction was not found. Micro-environments and microbial conversions in flocs from bulking and non-bulking activated sludge were determined with microsensors for H2S, O2, NO2− and NO3−. Denitrification and sulfate reduction rates were mmeasured with 15N- and 35S-tracer techniques. We showed that under normal reactor conditions (ca. 20% air saturation) anoxic zones develop within flocs allowing denitrification. The denitrification rates amounted to 40% of the rat

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2

Deutsch, Curtis, William Berelson, Robert Thunell, et al. "Centennial changes in North Pacific anoxia linked to tropical trade winds." Science 345, no. 6197 (2014): 665–68. http://dx.doi.org/10.1126/science.1252332.

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Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ15N) from multiple sediment cores. Increasing δ15N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ15N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwel

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3

Albertson, O. E., and H. D. Stensel. "Aerated Anoxic Biological NdeN Process." Water Science and Technology 29, no. 7 (1994): 167–76. http://dx.doi.org/10.2166/wst.1994.0334.

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The conventional practice for an anoxic denitrification basin has been to minimize oxygen input on the basis that it is detrimental to the process. For existing secondary treatment systems, allotting 25-35% of the aeration volume for an unaerated anoxic zone will significantly reduce plant capacity. Further, one group has held that bulking control is best achieved by eliminating all forms of oxygen from the initial contact or biological selector zones. The Phoenix 91st Avenue WWTP was designed with nitrate recycle to aerated selector zones and the anoxic zones were provided with a dense array

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4

Stevens, Gerald M., James L. Barnard, and Barry Rabinowitz. "Optimizing Biological Nutrient Removal in anoxic zones." Water Science and Technology 39, no. 6 (1999): 113–18. http://dx.doi.org/10.2166/wst.1999.0275.

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During the initial years of the development of Biological Nutrient Removal (BNR) technology, it was assumed that the bacterial species responsible of the removal of phosphorus (BioP organisms) could not use nitrates as a final electron acceptor and could thus not denitrify. The carbon taken up in the form of Volatile Fatty Acids (VFA) in the anaerobic zone was thus deemed to be unavailable for denitrification in the anoxic zone. This was reinforced through experiments in which BioP organisms cultured in the high-rate Phoredox system in which no nitrification took place, did not denitrify when

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5

Jacobs, Judith. "Anoxic “dead zones” in oceans." Eos, Transactions American Geophysical Union 85, no. 14 (2004): 134. http://dx.doi.org/10.1029/2004eo140006.

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6

Schramm, Andreas, Cecilia M. Santegoeds, Helle K. Nielsen, et al. "On the Occurrence of Anoxic Microniches, Denitrification, and Sulfate Reduction in Aerated Activated Sludge." Applied and Environmental Microbiology 65, no. 9 (1999): 4189–96. http://dx.doi.org/10.1128/aem.65.9.4189-4196.1999.

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ABSTRACT A combination of different methods was applied to investigate the occurrence of anaerobic processes in aerated activated sludge. Microsensor measurements (O2, NO2 −, NO3 −, and H2S) were performed on single sludge flocs to detect anoxic niches, nitrate reduction, or sulfate reduction on a microscale. Incubations of activated sludge with15NO3 − and35SO4 2− were used to determine denitrification and sulfate reduction rates on a batch scale. In four of six investigated sludges, no anoxic zones developed during aeration, and consequently denitrification rates were very low. However, in tw

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7

Garcia-Robledo, Emilio, Cory C. Padilla, Montserrat Aldunate, et al. "Cryptic oxygen cycling in anoxic marine zones." Proceedings of the National Academy of Sciences 114, no. 31 (2017): 8319–24. http://dx.doi.org/10.1073/pnas.1619844114.

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Oxygen availability drives changes in microbial diversity and biogeochemical cycling between the aerobic surface layer and the anaerobic core in nitrite-rich anoxic marine zones (AMZs), which constitute huge oxygen-depleted regions in the tropical oceans. The current paradigm is that primary production and nitrification within the oxic surface layer fuel anaerobic processes in the anoxic core of AMZs, where 30–50% of global marine nitrogen loss takes place. Here we demonstrate that oxygenic photosynthesis in the secondary chlorophyll maximum (SCM) releases significant amounts of O2to the other

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8

Bartlett, Rick, Maya Elrick, James R. Wheeley, Victor Polyak, André Desrochers, and Yemane Asmerom. "Abrupt global-ocean anoxia during the Late Ordovician–early Silurian detected using uranium isotopes of marine carbonates." Proceedings of the National Academy of Sciences 115, no. 23 (2018): 5896–901. http://dx.doi.org/10.1073/pnas.1802438115.

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Widespread marine anoxia is hypothesized as the trigger for the second pulse of the Late Ordovician (Hirnantian) mass extinction based on lithologic and geochemical proxies that record local bottom waters or porewaters. We test the anoxia hypothesis using δ238U values of marine limestones as a global seawater redox proxy. The δ238U trends at Anticosti Island, Canada, document an abrupt late Hirnantian ∼0.3‰ negative shift continuing through the early Silurian indicating more reducing seawater conditions. The lack of observed anoxic facies and no covariance among δ238U values and other local re

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9

Raven, M. R., R. G. Keil, and S. M. Webb. "Microbial sulfate reduction and organic sulfur formation in sinking marine particles." Science 371, no. 6525 (2020): 178–81. http://dx.doi.org/10.1126/science.abc6035.

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Climate change is driving an expansion of marine oxygen-deficient zones, which may alter the global cycles of carbon, sulfur, nitrogen, and trace metals. Currently, however, we lack a full mechanistic understanding of how oxygen deficiency affects organic carbon cycling and burial. Here, we show that cryptic microbial sulfate reduction occurs in sinking particles from the eastern tropical North Pacific oxygen-deficient zone and that some microbially produced sulfide reacts rapidly to form organic sulfur that is resistant to acid hydrolysis. Particle-hosted sulfurization could enhance carbon pr

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10

Ruano, M. V., J. Ribes, A. Seco, and J. Ferrer. "Low cost-sensors as a real alternative to on-line nitrogen analysers in continuous systems." Water Science and Technology 60, no. 12 (2009): 3261–68. http://dx.doi.org/10.2166/wst.2009.607.

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This paper is focused on the evaluation of the applicability of low-cost sensors (pH and ORP) versus nutrient analysers for controlling biological nitrogen removal in WWTPs. A nutrient removal pilot plant located in Carraixet WWTP (Valencia, Spain) that is equipped with a significant number of nutrient analysers and low-cost sensors was used. The relations between reliable, cheap on-line sensors such as pH and ORP (located in anaerobic, anoxic and aerobic zones) and the nitrification/denitrification processes are provided. The nitrification process can be evaluated by measuring the pH differen

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11

Wolke, Philipp, Yoni Teitelbaum, Chao Deng, Jörg Lewandowski, and Shai Arnon. "Impact of Bed Form Celerity on Oxygen Dynamics in the Hyporheic Zone." Water 12, no. 1 (2019): 62. http://dx.doi.org/10.3390/w12010062.

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Oxygen distribution and uptake in the hyporheic zone regulate various redox-sensitive reactions and influence habitat conditions. Despite the fact that fine-grain sediments in streams and rivers are commonly in motion, most studies on biogeochemistry have focused on stagnant sediments. In order to evaluate the effect of bed form celerity on oxygen dynamics and uptake in sandy beds, we conducted experiments in a recirculating indoor flume. Oxygen distribution in the bed was measured under various celerities using 2D planar optodes. Bed morphodynamics were measured by a surface elevation sensor

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12

Sarioglu, M., and N. Horan. "An equation for the empirical design of anoxic zones used to eliminate rising sludges at nitrifying activated sludge plants." Water Science and Technology 33, no. 3 (1996): 185–94. http://dx.doi.org/10.2166/wst.1996.0070.

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Anoxic zones are designed for the removal of nitrogen in nitrifying activated sludge plants. This can be carried out either to achieve a nitrogen discharge consent or to eliminate the problem of rising sludges. The rising sludge problem is mostly encountered in medium and small size plants in warm conditions and there is limited information as to the appropriate design of anoxic zones to protect against rising sludges in the secondary sedimentation tanks. Therefore a series of batch experiments were undertaken in order to establish the critical concentration of nitrate-nitrogen which causes ri

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13

Lüdemann, Heiner, Inko Arth, and Werner Liesack. "Spatial Changes in the Bacterial Community Structure along a Vertical Oxygen Gradient in Flooded Paddy Soil Cores." Applied and Environmental Microbiology 66, no. 2 (2000): 754–62. http://dx.doi.org/10.1128/aem.66.2.754-762.2000.

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ABSTRACT Molecular ecology techniques were applied to assess changes in the bacterial community structure along a vertical oxygen gradient in flooded paddy soil cores. Microsensor measurements showed that oxygen was depleted from 140 μM at the floodwater/soil interface to nondetectable amounts at a depth of approximately 2.0 mm and below. Bacterial 16S rRNA gene (rDNA)-based community fingerprint patterns were obtained from 200-μm-thick soil slices of both the oxic and anoxic zones by using the T-RFLP (terminal restriction fragment length polymorphism) technique. The fingerprints revealed a tr

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14

Rensink, J. H., J. van der Ven, G. van Pamelen, F. Fedder, and E. Majoor. "The modified renphosystem: a high biological nutrient removal system." Water Science and Technology 35, no. 10 (1997): 137–46. http://dx.doi.org/10.2166/wst.1997.0376.

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Pilot plant studies on high biological nutrient removal and using settled domestic wastewaters have been carried out with the so-called Modified Renphosystem. The system consists of a bioreactor which has been divided into four zones: anaerobic, aerobic, anoxic and aerobic, respectively. In the by-pass of the bioreactor a part of the return sludge was stripped in a stripper tank. The process of P-release was accelerated by dosage of acetate. The Modified Renphosystem is characterized by distribution of the stripped sludge to the first aerobic zone and the anoxic zone. In the aerobic nitrificat

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15

Ulloa, O., D. E. Canfield, E. F. DeLong, R. M. Letelier, and F. J. Stewart. "Microbial oceanography of anoxic oxygen minimum zones." Proceedings of the National Academy of Sciences 109, no. 40 (2012): 15996–6003. http://dx.doi.org/10.1073/pnas.1205009109.

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16

Karakitsios, V., H. Tsikos, K. Agiadi - Katsiaouni, S. Dermitzoglou, and E. Chatziharalambous. "THE USE OF CARBON AND OXYGEN STABLE ISOTOPES IN THE STUDY OF GLOBAL PALAEOCEANOGRAPHIC CHANGES: EXAMPLES FROM THE CRETACEOUS SEDIMENT ROCKS OF WESTERN GREECE." Bulletin of the Geological Society of Greece 39, no. 1 (2006): 64. http://dx.doi.org/10.12681/bgsg.18445.

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In the present paper we examine the use of carbon and oxygen stable isotopes in the study of global palaeoceanographic changes, with special reference to the oceanic anoxic events (OAEs). The analysis of stable isotopes was applied to the examination of Cretaceous sediments from the Ionian and Pindos zones of Western Greece. In the Ionian zone the carbon and oxygen stable isotopes, combined with biostratigraphic data, record the palaeoenvironmental change corresponding to the anoxic events Bonarelli (Cenomanian/Turonian, OAE2) and Paquier (Lower Albian, OAE1b). In the Pindos zone, within the C

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17

Phung, Anh Duc, M. Othman, and J. Yulian. "Effect of sucrose on denitrification through simulation, lab-scaled batch tests and pilot plants." Science and Technology Development Journal 17, no. 4 (2014): 22–32. http://dx.doi.org/10.32508/stdj.v17i4.1535.

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The aim of this study was to assess the impact of sucrose as external carbon source on denitrification. The specific denitrification rate (SDNR) determined using batch tests showed that acclimation to sucrose can increase SDNR in post and pre-anoxic denitrification zones by 47% and 116%, respectively. The use of sucrose in pre-anoxic zone led to an SDNR of 2.72±0.15 mg NO3- N/g MLVSS/h. This is 2.1 times higher than in the absence of external carbon and 1.7 times higher than the SDNR when sucrose was added into post-anoxic zone. The experiment has also tested the effect of sucrose on a pre-ano

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18

Wanner, Jiri, and Petr Grau. "Filamentous Bulking in Nutrient Removal Activated Sludge Systems." Water Science and Technology 20, no. 4-5 (1988): 1–8. http://dx.doi.org/10.2166/wst.1988.0149.

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Behaviour of filamentous microorganisms under anaerobic, anoxic, and oxic conditions has been reviewed from the point of view of filamentous bulking in nutrient removal activated sludge systems. It was concluded that the growth of most filamentous microorganisms is considerably suppressed under anaerobic and anoxic conditions and that the filamentous bulking in nutrient removal systems is chiefly caused by the growth of filamentous microorganisms in oxic zones. The role of particulate substrate hydrolysis was also discussed and the necessity of compartmentalization of oxic zones was shown.

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19

Çinar, Ö., T. Deniz, and C. P. L. Grady. "Effect of oxygen on the stability and inducibility of the biodegradative capability of benzoate." Water Science and Technology 48, no. 8 (2003): 247–54. http://dx.doi.org/10.2166/wst.2003.0475.

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Anoxic zones in biological nitrogen removal systems are typically open to the atmosphere and receive oxygen from the atmosphere and the recirculation flow from the aerobic zone. This raises the question of how such oxygen input might influence the stability and inducibility of the enzyme systems involved in biodegradation of aromatic compounds. To investigate this, various amounts of oxygen were added to mixed culture denitrifying chemostats receiving benzoate at 667 mg/h as chemical oxygen demand (COD), and the stability and inducibility of the culture’s benzoate biodegradative capability (BB

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20

Naqvi, S. W. A., H. W. Bange, L. Farías, P. M. S. Monteiro, M. I. Scranton, and J. Zhang. "Coastal hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O." Biogeosciences Discussions 6, no. 5 (2009): 9455–523. http://dx.doi.org/10.5194/bgd-6-9455-2009.

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Abstract. We review here available information on distributions of methane (CH4) and nitrous oxide (N2O) from major, mostly coastal, oxygen (O2)-deficient zones produced due to both natural processes and human activities (mainly eutrophication). Concentrations of both gases in subsurface waters are affected by ambient O2 levels. In the case of CH4, bottom-water O2 content probably affects emission from sediments, believed to be the main source of water-column CH4, as well as its oxidative loss in water itself. Highest CH4 accumulation (several μM) occurs in silled basins having anoxic deep wat

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21

MARYNOWSKI, LESZEK, PAWEŁ FILIPIAK, and MICHAŁ ZATOŃ. "Geochemical and palynological study of the Upper Famennian Dasberg event horizon from the Holy Cross Mountains (central Poland)." Geological Magazine 147, no. 4 (2010): 527–50. http://dx.doi.org/10.1017/s0016756809990835.

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AbstractIntegrated palynological, organic and inorganic geochemical and petrographical methods have been used for deciphering the depositional redox conditions and character of organic matter of the Famennian Dasberg event horizon from the deep-shelf Kowala succession of the Holy Cross Mountains. The ages of the investigated samples have been established, using miospore data, as VF (Diducites versabilis–Grandispora famenensis) and LV (Retispora lepidophyta–Apiculiretusispora verrucosa) miospore Zones of the Middle/Upper Famennian. In the standard conodont zonation, this corresponds to the uppe

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22

Funamizu, Naoyuki, Shoichiro Yamamoto, Yoshio Kitagawa, and Tetsuo Takakuwa. "Simulation of the operational conditions of the full-scale municipal wastewater treatment plant to improve the performance of nutrient removal." Water Science and Technology 36, no. 12 (1997): 9–18. http://dx.doi.org/10.2166/wst.1997.0425.

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Simulation analysis based on a mathematical model is one of the powerful tools for determining the operational conditions for a full scale biological nutrient removal plant. The model that included the Activated Sludge Model No.2 was developed for simulating the performance of the plant in Sapporo City. The investigated plant has the biological reaction basin which consists of the four zones, anaerobic-aerobic-anoxic-aerobic phases with the step feed of the primary effluent to the anaerobic and anoxic zones. We performed three experiments to calibrate and verify our model: (i) Characterization

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23

Huang, Yu, Yongzhen Peng, Donghui Huang, Jiarui Fan, and Rui Du. "Enhanced Nitrogen Removal from Domestic Wastewater by Partial-Denitrification/Anammox in an Anoxic/Oxic Biofilm Reactor." Processes 10, no. 1 (2022): 109. http://dx.doi.org/10.3390/pr10010109.

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A partial-denitrification coupling with anaerobic ammonium oxidation (anammox) process (PD/A) in a continuous-flow anoxic/oxic (A/O) biofilm reactor was developed to treat carbon-limited domestic wastewater (ammonia (NH4+-N) of 55 mg/L and chemical oxygen demand (COD) of 148 mg/L in average) for about 200 days operation. Satisfactory NH4+-N oxidation efficiency above 95% was achieved with rapid biofilm formation in the aerobic zone. Notably, nitrite (NO2−-N) accumulation was observed in the anoxic zone, mainly due to the insufficient electron donor for complete nitrate (NO3−-N) reduction. The

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24

Fontanos, P. M., K. Yamamoto, and F. Nakajima. "Effect of upflow velocity on the performance of an inclined plate membrane bioreactor treating municipal wastewater." Water Science and Technology 64, no. 5 (2011): 1102–7. http://dx.doi.org/10.2166/wst.2011.142.

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An inclined plate membrane bioreactor (iPMBR) was introduced to meet the challenge of handling high mixed liquor suspended solids when operating at long sludge retention times. During the first 407 days of operation, the iPMBR was able to rezone more sludge (1.5–10.5 times greater) in its upstream, anoxic tank compared to its downstream, aerobic tank. This could extend membrane filtration by diverting most of the sludge from the aerobic zone. During this period, the upflow velocities through the inclined plates of the anoxic tank ranged from 2.3 × 10−4 to 7.7 × 10−4 m/s. After Day 407, the ope

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25

Wielinga, Bruce, Juliette K. Lucy, Johnnie N. Moore, October F. Seastone, and James E. Gannon. "Microbiological and Geochemical Characterization of Fluvially Deposited Sulfidic Mine Tailings." Applied and Environmental Microbiology 65, no. 4 (1999): 1548–55. http://dx.doi.org/10.1128/aem.65.4.1548-1555.1999.

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ABSTRACT The fluvial deposition of mine tailings generated from historic mining operations near Butte, Montana, has resulted in substantial surface and shallow groundwater contamination along Silver Bow Creek. Biogeochemical processes in the sediment and underlying hyporheic zone were studied in an attempt to characterize interactions consequential to heavy-metal contamination of shallow groundwater. Sediment cores were extracted and fractionated based on sediment stratification. Subsamples of each fraction were assayed for culturable heterotrophic microbiota, specific microbial guilds involve

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Elshaw, Andrew, Nur M. S. Hassan, and M. Masud K. Khan. "Computational Fluid Dynamic Modelling and Optimisation of Wastewater Treatment Plant Bioreactor Mixer." Energies 11, no. 12 (2018): 3530. http://dx.doi.org/10.3390/en11123530.

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This study aims to determine the optimal configuration (position and operation duration) for wall mounted mechanical mixers based on the comparison of three-dimensional computational fluid dynamics (CFD) modelling results and physical data collected from the treatment plant. A three dimensional model of anoxic zone in 1, 2 and 3 of Northern Wastewater Treatment Plant (NWWTP) located at Cairns Regional Council, Cairns, Queensland, Australia was developed and validated. The model was used to simulate the flow pattern of the WWTP and the simulation results are in good agreement with the physical

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27

Brenner, Asher. "Modification of Small Activated Sludge Plants to Recycled Systems for Nitrogen Removal and Control of Settling Properties." Water Science and Technology 22, no. 3-4 (1990): 117–22. http://dx.doi.org/10.2166/wst.1990.0191.

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Modification of small activated sludge plants to recycled systems is proposed as a means to improve nitrogen removal and control of settling properties. The modification process involves separation of the aeration basin to anoxic and aerobic zones and addition of internal recycle of mixed liquor from the aerobic to the anoxic zone. This mode of operation may prevent problems of floating sludge in the final clarifier caused by uncontrolled denitrification. In the recycled system, part of the organic carbon is removed under anoxic conditions. Therefore, it may assist in the selection of microbia

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van der Wielen, P. W. J. J., M. Blokker, and G. J. Medema. "Modelling the length of microbiological protection zones around phreatic sandy aquifers in The Netherlands." Water Science and Technology 54, no. 3 (2006): 63–69. http://dx.doi.org/10.2166/wst.2006.449.

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The aim of the current study was to calculate the size of protection zones around (sub)oxic and anoxic sandy aquifers without confining layers using a virus infection and transport model. The maximum allowable virus infection risk was 10−4/person/year at the 95% confidence level. Model results demonstrated that phreatic (sub)oxic sandy aquifers in The Netherlands required protection areas with a residence time of 43–117 d to ensure that the maximum virus infection risk would not be exceeded. This was 0.7–2× the current guideline of 60 d. In contrast, phreatic anoxic sandy aquifers without conf

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Zakem, Emily J., Amala Mahadevan, Jonathan M. Lauderdale, and Michael J. Follows. "Stable aerobic and anaerobic coexistence in anoxic marine zones." ISME Journal 14, no. 1 (2019): 288–301. http://dx.doi.org/10.1038/s41396-019-0523-8.

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Abstract Mechanistic description of the transition from aerobic to anaerobic metabolism is necessary for diagnostic and predictive modeling of fixed nitrogen loss in anoxic marine zones (AMZs). In a metabolic model where diverse oxygen- and nitrogen-cycling microbial metabolisms are described by underlying redox chemical reactions, we predict a transition from strictly aerobic to predominantly anaerobic regimes as the outcome of ecological interactions along an oxygen gradient, obviating the need for prescribed critical oxygen concentrations. Competing aerobic and anaerobic metabolisms can coe

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Goggin, Danica E., and Timothy D. Colmer. "Intermittent anoxia induces oxidative stress in wheat seminal roots: assessment of the antioxidant defence system, lipid peroxidation and tissue solutes." Functional Plant Biology 32, no. 6 (2005): 495. http://dx.doi.org/10.1071/fp04194.

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The effects of continuous and intermittent anoxia on components of the antioxidant defence system were evaluated in the expanded zones of wheat seedling roots. Intermittent anoxia caused oxidative stress (measured by the proportion of reduced glutathione) after three cycles of anoxia–aeration. The concentration of glutathione and activities of glutathione reductase (GR) and catalase (CAT) were decreased by 50% under both continuous and intermittent anoxia. Ascorbate peroxidase (APX) activity was unaffected by anoxia but stimulated almost 2-fold during the aerated periods of intermittent anoxia

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Morard, Alain, Jean Guex, Annachiara Bartolini, Elena Morettini, and Patrick de Wever. "A new scenario for the Domerian - Toarcian transition." Bulletin de la Société Géologique de France 174, no. 4 (2003): 351–56. http://dx.doi.org/10.2113/174.4.351.

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Abstract In contrast to the majority of recently published hypotheses, we believe that the main trigger for early Toarcian anoxia is neither increased primary productivity during the Tenuicostatum and Falciferum Zones nor sudden methane hydrate degassing close to the transition between these two zones. In our opinion, this peculiar paleoceanographic episode is linked to a major, though short-lived, regression at the end of Upper Domerian. Sea-level fall resulted from sudden cooling due to increased volcanic activity. This generated global thermal insulation and subsequent glaciation. The regre

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Naqvi, S. W. A., H. W. Bange, L. Farías, P. M. S. Monteiro, M. I. Scranton, and J. Zhang. "Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O." Biogeosciences 7, no. 7 (2010): 2159–90. http://dx.doi.org/10.5194/bg-7-2159-2010.

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Abstract. We review here the available information on methane (CH4) and nitrous oxide (N2O) from major marine, mostly coastal, oxygen (O2)-deficient zones formed both naturally and as a result of human activities (mainly eutrophication). Concentrations of both gases in subsurface waters are affected by ambient O2 levels to varying degrees. Organic matter supply to seafloor appears to be the primary factor controlling CH4 production in sediments and its supply to (and concentration in) overlying waters, with bottom-water O2-deficiency exerting only a modulating effect. High (micromolar level) C

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Saunders, Jaclyn K., Clara A. Fuchsman, Cedar McKay, and Gabrielle Rocap. "Complete arsenic-based respiratory cycle in the marine microbial communities of pelagic oxygen-deficient zones." Proceedings of the National Academy of Sciences 116, no. 20 (2019): 9925–30. http://dx.doi.org/10.1073/pnas.1818349116.

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Microbial capacity to metabolize arsenic is ancient, arising in response to its pervasive presence in the environment, which was largely in the form of As(III) in the early anoxic ocean. Many biological arsenic transformations are aimed at mitigating toxicity; however, some microorganisms can respire compounds of this redox-sensitive element to reap energetic gains. In several modern anoxic marine systems concentrations of As(V) are higher relative to As(III) than what would be expected from the thermodynamic equilibrium, but the mechanism for this discrepancy has remained unknown. Here we pre

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Kafousia, N., V. Karakitsios, E. Mattioli, and H. C. Jenkyns. "Chemostratigraphy of the Toarcian oceanic anoxic event from the Ionian Zone, Greece." Bulletin of the Geological Society of Greece 47, no. 2 (2017): 825. http://dx.doi.org/10.12681/bgsg.11119.

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A global perturbation in the carbon cycle has been recorded in the Early Toarcian (~ 183 Ma) and is marked by enhanced organic-carbon burial and mass extinction. It is also associated with high palaeotemperatures, both positive and negative excursions in carbon-isotope ratios, and the development of anoxic to euxinic conditions in marine environments: together these phenomena have been designated as constituting an Oceanic Anoxic Event. Here we provide a high-resolution, multiproxy biostratigraphic and chemostratigraphic study from a section that belongs to the central Ionian Zone in Greece. C

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Rensink, J. H., E. Eggers, and H. J. G. W. Donker. "High Biological Nutrient Removal from Domestic Wastewater in Combination with Phosphorus Recycling." Water Science and Technology 23, no. 4-6 (1991): 651–57. http://dx.doi.org/10.2166/wst.1991.0515.

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Pilot plant studies on biological nutrient removal and using settled domestic waste water have been carried out in combination with phosphorus recycling on the basis of crystallisation of calcium phosphate on sand pellets in a fluidized bed-reactor. The bioreactor had been divided into four zones, respectively anaerobic, aerobic, anoxic and aerobic. To eliminate nitrate sludge recirculation for denitrification, a part of the influent was led to the anoxic zone. In the by-pass of the bioreactor a phostripper tank was incorporated followed by a fluidized bed-reactor. The experiments carried out

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Jakobs, G., G. Rehder, G. Jost, K. Kießlich, M. Labrenz, and O. Schmale. "Comparative studies of pelagic microbial methane oxidation within two anoxic basins of the central Baltic Sea (Gotland Deep and Landsort Deep)." Biogeosciences Discussions 10, no. 7 (2013): 12251–84. http://dx.doi.org/10.5194/bgd-10-12251-2013.

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Abstract. Pelagic methane oxidation was investigated in dependence on differing environmental conditions within the redox zone of the Gotland Deep (GD) and Landsort Deep (LD), central Baltic Sea. The redox zone of both deeps, which indicates the transition between oxic and anoxic conditions, was characterized by a pronounced methane concentration gradient between the deep water (GD: 1233 nM, LD: 2935 nM) and the surface water (GD and LD < 10 nM), together with a 13C CH4 enrichment (δ13C CH4 deep water: GD −84‰, LD −71‰ ; redox zone: GD −60‰, LD −20‰ ; δ13C CH4 vs. Vienna Pee Dee Belemnite s

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Asadi, A., A. A. Zinatizadeh, M. Van Loosdrecht, and H. Younesi. "Nitrogen removal by ANAMMOX and simultaneous nitrification–denitrification (SND) processes in a novel single airlift bioreactor." RSC Advances 6, no. 78 (2016): 74367–71. http://dx.doi.org/10.1039/c6ra11174b.

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The aim of this research was to assess anaerobic ammonium oxidation and simultaneous nitrification–denitrification processes in a novel continuous feed and intermittent discharge airlift bioreactor which provides anaerobic, anoxic and aerobic zones by physical separation.

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Bishop, Janice L., Brandy L. Anglen, Lisa M. Pratt, Howell G. M. Edwards, David J. Des Marais, and Peter T. Doran. "A spectroscopy and isotope study of sediments from the Antarctic Dry Valleys as analogues for potential paleolakes on Mars." International Journal of Astrobiology 2, no. 4 (2003): 273–87. http://dx.doi.org/10.1017/s1473550403001654.

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A spectroscopy and isotope study has been performed on igneous sediments from Lake Hoare, a nearly isolated ecosystem in the Dry Valleys region of Antarctica. The mineralogy and chemistry of these sediments were studied in order to gain insights into the biogeochemical processes occurring in a permanently ice-covered lake and to assist in characterizing potential habitats for life in paleolakes on Mars. Obtaining visible/near-infrared, mid-infrared and Raman spectra of such sediments provides the ground truth needed for using reflectance, emittance and Raman spectroscopy for exploration of geo

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Bellandi, Giacomo, Jose Porro, Elisa Senesi, et al. "Multi-point monitoring of nitrous oxide emissions in three full-scale conventional activated sludge tanks in Europe." Water Science and Technology 77, no. 4 (2017): 880–90. http://dx.doi.org/10.2166/wst.2017.560.

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Abstract The large global warming potential of nitrous oxide (N2O) is currently of general concern for the water industry, especially in view of a new regulatory framework concerning the carbon footprint of water resource recovery facilities (WRRFs). N2O can be generated through different biological pathways and from different treatment steps of a WRRF. The use of generic emission factors (EF) for quantifying the emissions of WRRFs is discouraged. This is due to the number of different factors that can affect how much, when and where N2O is emitted from WRRFs. The spatial and temporal variabil

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Lee, T. T., F. Y. Wang, and R. B. Newell. "On the modelling and simulation of a BNR activated sludge process based on distributed parameter approach." Water Science and Technology 39, no. 6 (1999): 79–88. http://dx.doi.org/10.2166/wst.1999.0266.

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A computational algorithm, based on an orthogonal collocation approach is developed to simulate a BNR activated sludge process consisting of anaerobic, anoxic and aerobic zones in a back-to-back scheme. The hydraulic model employed in this study considers backmixing or intermixing, which can represent the actual process more accurately than the idealised flow schemes commonly employed for modelling and/or design of the activated sludge bioreactor. The kinetic model of the International Association on Water Quality (IAWQ) - Activated Sludge Model No. 2 (ASM No. 2) was reduced to submodels repre

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Sriwiriyarat, Tongchai, and Clifford W. Randall. "THE PERFORMANCE OF IFAS MEDIA IN ANOXIC ZONES OF BNR SYSTEMS." Proceedings of the Water Environment Federation 2007, no. 2 (2007): 1075–97. http://dx.doi.org/10.2175/193864707787976830.

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Penn, Justin L., Thomas Weber, Bonnie X. Chang, and Curtis Deutsch. "Microbial ecosystem dynamics drive fluctuating nitrogen loss in marine anoxic zones." Proceedings of the National Academy of Sciences 116, no. 15 (2019): 7220–25. http://dx.doi.org/10.1073/pnas.1818014116.

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The dynamics of nitrogen (N) loss in the ocean’s oxygen-deficient zones (ODZs) are thought to be driven by climate impacts on ocean circulation and biological productivity. Here we analyze a data-constrained model of the microbial ecosystem in an ODZ and find that species interactions drive fluctuations in local- and regional-scale rates of N loss, even in the absence of climate variability. By consuming O2to nanomolar levels, aerobic nitrifying microbes cede their competitive advantage for scarce forms of N to anaerobic denitrifying bacteria. Because anaerobes cannot sustain their own low-O2n

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Haberstroh, P. R., and F. J. Sansone. "Reef framework diagenesis across wave-flushed oxic-suboxic-anoxic transition zones." Coral Reefs 18, no. 3 (1999): 229–40. http://dx.doi.org/10.1007/s003380050187.

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Canfield, Don E., Beate Kraft, Carolin R. Löscher, Richard A. Boyle, Bo Thamdrup, and Frank J. Stewart. "The regulation of oxygen to low concentrations in marine oxygen-minimum zones." Journal of Marine Research 77, no. 3 (2019): 297–324. http://dx.doi.org/10.1357/002224019828410548.

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The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygen in its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in the global ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California, as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in the Eastern Tropical North Pacific. We show here that biological controls on oxygen consumption are required to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise, only small changes in ph

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van Grinsven, Sigrid, Kirsten Oswald, Bernhard Wehrli, et al. "Methane oxidation in the waters of a humic-rich boreal lake stimulated by photosynthesis, nitrite, Fe(III) and humics." Biogeosciences 18, no. 10 (2021): 3087–101. http://dx.doi.org/10.5194/bg-18-3087-2021.

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Abstract. Small boreal lakes are known to contribute significantly to global CH4 emissions. Lake Lovojärvi is a eutrophic lake in southern Finland with bottom water CH4 concentrations up to 2 mM. However, the surface water concentration, and thus the diffusive emission potential, was low (< 0.5 µM). We studied the biogeochemical processes involved in CH4 removal by chemical profiling and through incubation experiments. δ13C-CH4 profiling of the water column revealed a methane-oxidation hotspot just below the oxycline and zones of CH4 oxidation within the anoxic water column. In incubation e

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Chao, Yeong-Nan, Jui-Hsien Lin, Kok-Kwang Ng, Chung-Hsin Wu, Pui-Kwan Andy Hong, and Cheng-Fang Lin. "Improving total nitrogen removal in aeration basin retrofitted with entrapped biomass." Water Science and Technology 69, no. 7 (2014): 1558–64. http://dx.doi.org/10.2166/wst.2014.053.

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This study presented a method to upgrade existing aeration tanks to remove total nitrogen (TN). Bioplates carrying entrapped biomass were installed in an aeration basin to create anoxic/anaerobic zones where denitrification can proceed. In a reactor that coupled bioplates containing entrapped biomass (equivalent to as high as 7,500 mg/L of biomass) and an activated sludge suspension (at mixed liquor suspended solids of 1,300–2,400 mg/L), nitrification efficiency exceeded 95% for an influent wastewater containing 21–54 mg/L of NH3-N. In all cases amended with alkalinity and with or without adde

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Shuo, Liu, Wang Baozhen, Han Hongjun, and Liu Yanping. "New process for alleviation of membrane fouling of modified hybrid MBR system for advanced domestic wastewater treatment." Water Science and Technology 58, no. 10 (2008): 2059–66. http://dx.doi.org/10.2166/wst.2008.755.

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A pilot-scale hybrid membrane bioreactor using a submerged flat panel membrane was designed and applied for advanced treatment of domestic wastewater. The new process adapted to the hybrid membrane bioreactor exhibits substantial decrease in membrane fouling and much easier cleaning. In this study, the new process configurations including the addition of anoxic/anaerobic zones, the package of synthetic fibrous fabric carrier for biofilm attached growth, activated sludge recycling and modified dosage of polished diatomite with high activity and multi-functions were investigated to select the op

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Berndmeyer, C., V. Thiel, O. Schmale, N. Wasmund, and M. Blumenberg. "Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)." Biogeosciences 11, no. 23 (2014): 7009–23. http://dx.doi.org/10.5194/bg-11-7009-2014.

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Abstract. The water column of the Landsort Deep, central Baltic Sea, is stratified into an oxic, suboxic, and anoxic zone. This stratification controls the distributions of individual microbial communities and biogeochemical processes. In summer 2011, particulate organic matter was filtered from these zones using an in situ pump. Lipid biomarkers were extracted from the filters to establish water-column profiles of individual hydrocarbons, alcohols, phospholipid fatty acids, and bacteriohopanepolyols (BHPs). As a reference, a cyanobacterial bloom sampled in summer 2012 in the central Baltic Se

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Atkinson, B. W., D. D. Mudaly, and F. Bux. "Contribution of Pseudomonas spp. to phosphorus uptake in the anoxic zone of an anaerobic-anoxic-aerobic continuous activated sludge system." Water Science and Technology 43, no. 1 (2001): 139–46. http://dx.doi.org/10.2166/wst.2001.0034.

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A continuously operated laboratory-scale (32 L) nitrification denitrification biological excess phosphorus removal (NDBEPR) activated sludge system (modeled on the 3-stage Phoredox configuration) was maintained for 140 d. The transition from a non-biological excess phosphorus removal (BEPR) sludge to one exhibiting a strong BEPR mechanism was monitored. Mixed liquor seed inoculum was obtained from a full-scale single aerobic activated sludge installation and subjected to conditions conducive to BEPR, i.e. increasing influent acetate (HAc) concentrations. At a sludge age of 10 d with 100% HAc f

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Kurochkin, I. O., A. V. Ivanina, S. Eilers, C. A. Downs, L. A. May, and I. M. Sokolova. "Cadmium affects metabolic responses to prolonged anoxia and reoxygenation in eastern oysters (Crassostrea virginica)." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 297, no. 5 (2009): R1262—R1272. http://dx.doi.org/10.1152/ajpregu.00324.2009.

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Benthic marine organisms such as mollusks are often exposed to periodic oxygen deficiency (due to the tidal exposure and/or seasonal expansion of the oxygen-deficient dead zones) and pollution by metals [e.g., cadmium, (Cd)]. These stressors can strongly affect mollusks' survival; however, physiological mechanisms of their combined effects are not fully understood. We studied the effects of Cd exposure on metabolic responses to prolonged anoxia and subsequent recovery in anoxia-tolerant intertidal mollusks Crassostrea virginica (eastern oysters). Anoxia led to an onset of anaerobiosis indicate

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