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Abu A, Carrey R, Valhondo C, Domènech C, Soler A, Martínez-Landa L, Diaz-Cruz S, Carrera J, Otero N. Pathways and efficiency of nitrogen attenuation in wastewater effluent through soil aquifer treatment. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 321:115927. [PMID: 35994957 DOI: 10.1016/j.jenvman.2022.115927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/19/2022] [Accepted: 07/31/2022] [Indexed: 06/15/2023]
Abstract
Soil Aquifer Treatment (SAT) is used to increase groundwater resources and enhance the water quality of wastewater treatment plant (WWTP) effluents. The resulting water quality needs to be assessed. In this study, we investigate attenuation pathways of nitrogen (N) compounds (predominantly NH4+) from a secondary treatment effluent in pilot SAT systems: both a conventional one (SAT-Control system) and one operating with a permeable reactive barrier (PRB) to provide extra dissolved organic carbon to the recharged water. The goal is to evaluate the effectiveness of the two systems regarding N compounds by means of chemical and isotopic tools. Water chemistry (NO3-, NH4+, Non-Purgeable Dissolved Organic Carbon (NPDOC), and O2) and isotopic composition of NO3- (ẟ15N-NO3- and ẟ18O-NO3-) and NH4+ (ẟ15N-NH4+) were monitored in the inflow and at three different sections and depths along the aquifer flow path. Chemical and isotopic results suggest that coupled nitrification-denitrification were the principal mechanisms responsible for the migration and distribution of inorganic N in the systems and that nitrification rate decreased with depth. At the end of the study period, 66% of the total N in the solution was removed in the SAT-PRB system and 69% in the SAT-Control system, measured at the outlet of the systems. The residual N in solution in the SAT-PRB system had an approximately equal proportion of N-NH4+ and N-NO3- while in the SAT-Control system, the residual N in solution was primarily N-NO3-. Isotopic data also confirmed complete NO3- degradation in the systems from July to September with the possibility of mixing newly generated NO3- with the residual NO3- in the substrate pool.
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Affiliation(s)
- Alex Abu
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain.
| | - Raúl Carrey
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - Cristina Valhondo
- Université de Montpellier. UMR 5243 Géosciences Montpellier. 300 Avenue Emile Jeanbrau CC MSE. 34095, Montpellier, France; Université de Montpellier. UMR 5569 HydroSciences Montpellier. 15 Avenue Charles Flahault-BP 14491. 34093, Montpellier. France; Institute of Environmental Assessment and Water Research (IDAEA). Severo Ochoa Excellence Center. Spanish National Research Council (CSIC), Jordi Girona 18-24, 08034 Barcelona, Spain
| | - Cristina Domènech
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - Albert Soler
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain
| | - Lurdes Martínez-Landa
- Department of Civil and Environmental Engineering, Universitat Politecnica de Catalunya (UPC), Jordi Girona 1-3, 08034 Barcelona, Spain; Hydrogeology Group (UPC-CSIC), Associate Unit, Jordi Girona, 08034 Barcelona, Spain
| | - Silvia Diaz-Cruz
- Institute of Environmental Assessment and Water Research (IDAEA). Severo Ochoa Excellence Center. Spanish National Research Council (CSIC), Jordi Girona 18-24, 08034 Barcelona, Spain
| | - Jesús Carrera
- Institute of Environmental Assessment and Water Research (IDAEA). Severo Ochoa Excellence Center. Spanish National Research Council (CSIC), Jordi Girona 18-24, 08034 Barcelona, Spain; Hydrogeology Group (UPC-CSIC), Associate Unit, Jordi Girona, 08034 Barcelona, Spain
| | - Neus Otero
- Grup MAiMA, SGR Mineralogia Aplicada, Geoquímica I Geomicrobiologia, Departament de Mineralogia, Petrologia I Geologia Aplicada, Facultat de Ciències de La Terra, Universitat de Barcelona (UB), 08028, Barcelona, Catalonia, Spain; Institut de Recerca de L'Aigua (IdRA), Universitat de Barcelona (UB), 08001, Barcelona, Catalonia, Spain; Serra Húnter Fellowship. Generalitat de Catalunya, Catalonia, Spain
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Ramey AM, Reeves AB, Lagassé BJ, Patil V, Hubbard LE, Kolpin DW, McCleskey RB, Repert DA, Stallknecht DE, Poulson RL. Evidence for interannual persistence of infectious influenza A viruses in Alaska wetlands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 803:150078. [PMID: 34525758 PMCID: PMC9277558 DOI: 10.1016/j.scitotenv.2021.150078] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/26/2021] [Accepted: 08/28/2021] [Indexed: 06/13/2023]
Abstract
Influenza A viruses (IAVs) deposited by wild birds into the environment may lead to sporadic mortality events and economically costly outbreaks among domestic birds. There is a paucity of information, however, regarding the persistence of infectious IAVs within the environment following deposition. In this investigation, we assessed the persistence of 12 IAVs that were present in cloacal and/or oropharyngeal swabs of naturally infected ducks. Infectivity of these IAVs was monitored over approximately one year with each virus tested in five water types: (1) distilled water held in the lab at 4 °C and (2-5) filtered surface water from each of four Alaska sites and maintained in the field at ambient temperature. By evaluating infectivity of IAVs in ovo following sample retrieval at four successive time points, we observed declines in IAV infectivity through time. Many viruses persisted for extended periods, as evidenced by ≥25% of IAVs remaining infectious in replicate samples for each treatment type through three sampling time points (144-155 days post-sample collection) and two viruses remaining viable in a single replicate sample each when tested upon collection at a fourth time point (361-377 days post-sample collection). The estimated probability of persistence of infectious IAVs in all five water types was estimated to be between 0.25 and 0.75 during days 50-200 post-sample collection as inferred through Kaplan-Meier survival analysis. Our results provide evidence that IAVs may remain infectious for extended periods, up to or even exceeding one year, when maintained in surface waters under ambient temperatures. Therefore, wetlands may represent an important medium in which infectious IAVs may reside outside of a biotic reservoir.
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Affiliation(s)
- Andrew M Ramey
- U. S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA.
| | - Andrew B Reeves
- U. S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA.
| | - Benjamin J Lagassé
- U. S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA; Department of Biology and Wildlife, University of Alaska Fairbanks, P.O. Box 756100, Fairbanks, AK 99775, USA
| | - Vijay Patil
- U. S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA.
| | - Laura E Hubbard
- U. S. Geological Survey, Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA.
| | - Dana W Kolpin
- U. S. Geological Survey, Central Midwest Water Science Center, 400 S. Clinton Street, Iowa City, IA 52244, USA.
| | - R Blaine McCleskey
- U. S. Geological Survey, Water Resources Mission Area, 3215 Marine Street, Building 6, Boulder, CO 80309, USA.
| | - Deborah A Repert
- U. S. Geological Survey, Water Resources Mission Area, 3215 Marine Street, Building 6, Boulder, CO 80309, USA.
| | - David E Stallknecht
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
| | - Rebecca L Poulson
- Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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Tokranov AK, LeBlanc DR, Pickard HM, Ruyle BJ, Barber LB, Hull RB, Sunderland EM, Vecitis CD. Surface-water/groundwater boundaries affect seasonal PFAS concentrations and PFAA precursor transformations. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1893-1905. [PMID: 34779453 PMCID: PMC8673475 DOI: 10.1039/d1em00329a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Elevated concentrations of per- and polyfluoroalkyl substances (PFAS) in drinking-water supplies are a major concern for human health. It is therefore essential to understand factors that affect PFAS concentrations in surface water and groundwater and the transformation of perfluoroalkyl acid (PFAA) precursors that degrade into terminal compounds. Surface-water/groundwater exchange can occur along the flow path downgradient from PFAS point sources and biogeochemical conditions can change rapidly at these exchange boundaries. Here, we investigate the influence of surface-water/groundwater boundaries on PFAS transport and transformation. To do this, we conducted an extensive field-based analysis of PFAS concentrations in water and sediment from a flow-through lake fed by contaminated groundwater and its downgradient surface-water/groundwater boundary (defined as ≤100 cm below the lake bottom). PFAA precursors comprised 45 ± 4.6% of PFAS (PFAA precursors + 18 targeted PFAA) in the predominantly oxic lake impacted by a former fire-training area and historical wastewater discharges. In shallow porewater downgradient from the lake, this percentage decreased significantly to 25 ± 11%. PFAA precursor concentrations decreased by 85% between the lake and 84-100 cm below the lake bottom. PFAA concentrations increased significantly within the surface-water/groundwater boundary and in downgradient groundwater during the winter months despite lower stable concentrations in the lake water source. These results suggest that natural biogeochemical fluctuations associated with surface-water/groundwater boundaries may lead to PFAA precursor loss and seasonal variations in PFAA concentrations. Results of this work highlight the importance of dynamic biogeochemical conditions along the hydrological flow path from PFAS point sources to potentially affected drinking water supplies.
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Affiliation(s)
- Andrea K Tokranov
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
- U.S. Geological Survey, Northborough, MA 01532, USA
| | | | - Heidi M Pickard
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
| | - Bridger J Ruyle
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
| | | | | | - Elsie M Sunderland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA 02115, USA
| | - Chad D Vecitis
- Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, MA 02138, USA.
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Smith RL, Repert DA, Koch JC. Nitrogen biogeochemistry in a boreal headwater stream network in interior Alaska. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 764:142906. [PMID: 33115600 DOI: 10.1016/j.scitotenv.2020.142906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/28/2020] [Accepted: 10/03/2020] [Indexed: 06/11/2023]
Abstract
High latitude, boreal watersheds are nitrogen (N)-limited ecosystems that export large amounts of organic carbon (C). Key controls on C cycling in these environments are the biogeochemical processes affecting the N cycle. A study was conducted in Nome Creek, an upland tributary of the Yukon River, and two headwater tributaries to Nome Creek, to examine the relation between seasonal and transport-associated changes in C and N pools and N-cycling processes using laboratory bioassays of water and sediment samples and in-stream tracer tests. Dissolved organic nitrogen (DON) exceeded dissolved inorganic nitrogen (DIN) in Nome Creek except late in the summer season, with little variation in organic C:N ratios with time or transport distance. DIN was dominant in the headwater tributaries. Rates of organic N mineralization and denitrification in laboratory incubations were positively correlated with sediment organic C content, while nitrification rates differed greatly between two headwater tributaries with similar drainages. Additions of DIN or urea did not stimulate microbial activity. In-stream tracer tests with nitrate and urea indicated that uptake rates were slow relative to transport rates; simulated rates of uptake in stream storage zones were higher than rates assessed in the laboratory bioassays. In general, N-cycle processes were more active and had a greater overall impact in the headwater tributaries and were minimized in Nome Creek, the larger, higher velocity, transport-dominated stream. Given expectations of permafrost thaw and increased hydrologic cycling that will flush more inorganic N from headwater streams, our results suggest higher N loads from these systems in the future.
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Affiliation(s)
| | | | - Joshua C Koch
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK 99508, USA
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Xin J, Liu Y, Chen F, Duan Y, Wei G, Zheng X, Li M. The missing nitrogen pieces: A critical review on the distribution, transformation, and budget of nitrogen in the vadose zone-groundwater system. WATER RESEARCH 2019; 165:114977. [PMID: 31446294 DOI: 10.1016/j.watres.2019.114977] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/29/2019] [Accepted: 08/12/2019] [Indexed: 06/10/2023]
Abstract
Intensive agriculture and urbanization have led to the excessive and repeated input of nitrogen (N) into soil and further increased the amount of nitrate (NO3-) leaching into groundwater, which has become an environmental problem of widespread concern. This review critically examines both the recent advances and remaining knowledge gaps with respect to the N cycle in the vadose zone-groundwater system. The key aspects regarding the N distribution, transformation, and budget in this system are summarized. Three major missing N pieces (N in dissolved organic form, N in the deep vadose zone, and N in the nonagricultural system), which are crucial for closing the N cycle yet has been previously assumed to be insignificant, are put forward and discussed. More work is anticipated to obtain accurate information on the chemical composition, transformation mechanism, and leaching flux of these missing N pieces in the vadose zone-groundwater system. These are essential to support the assessment of global N stocks and management of N contamination risks.
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Affiliation(s)
- Jia Xin
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
| | - Yang Liu
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
| | - Fei Chen
- School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China
| | - Yijun Duan
- School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China
| | - Guanli Wei
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
| | - Xilai Zheng
- Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China
| | - Miao Li
- School of Environment, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing, 100084, China
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Nikolenko O, Jurado A, Borges AV, Knӧller K, Brouyѐre S. Isotopic composition of nitrogen species in groundwater under agricultural areas: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 621:1415-1432. [PMID: 29074237 DOI: 10.1016/j.scitotenv.2017.10.086] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 05/16/2023]
Abstract
This work reviews applications of stable isotope analysis to the studies of transport and transformation of N species in groundwater under agricultural areas. It summarizes evidence regarding factors affecting the isotopic composition of NO3-, NH4+ and N2O in subsurface, and discusses the use of 11B, 18O, 13C, 34S, 87Sr/86Sr isotopes to support the analysis of δ15N values. The isotopic composition of NO3-, NH4+ and N2O varies depending on their sources and dynamics of N cycle processes. The reported δ15N-NO3- values for sources of NO3- are: soil organic N - +3‰-+8‰, mineral fertilizers - -8‰-+7‰; manure/household waste - +5‰ to +35‰. For NH4+ sources, the isotopic signature ranges are: organic matter - +2.4-+4.1‰, rainwater - -13.4-+2.3‰, mineral fertilizers - -7.4-+5.1‰, household waste - +5-+9‰; animal manure - +8-+11‰. For N2O, isotopic composition depends on isotopic signatures of substrate pools and reaction rates. δ15N values of NO3- are influenced by fractionation effects occurring during denitrification (ɛ=5-40‰), nitrification (ɛ=5-35‰) and DNRA (ɛ not reported). The isotopic signature of NH4+ is also affected by nitrification and DNRA as well as mineralization (ɛ=1‰), sorption (ɛ=1-8‰), anammox (ɛ=4.3-7.4‰) and volatilization (ɛ=25‰). As for the N2O, production of N2O leads to its depletion in 15N, whereas consumption - to enrichment in 15N. The magnitude of fractionation effects occurring during the considered processes depends on temperature, pH, DO, C/NO3- ratio, size of the substrate pool, availability of electron donors, water content in subsoil, residence time, land use, hydrogeology. While previous studies have accumulated rich data on isotopic composition of NO3- in groundwater, evidence remains scarce in the cases of NH4+ and N2O. Further research is required to consider variability of δ15N-NH4+ and δ15N-N2O in groundwater across agricultural ecosystems.
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Affiliation(s)
- Olha Nikolenko
- University of Liѐge, ArGEnCo, Hydrogeology and Environmental Geology, Aquapôle, -B52/3 Sart-Tilman, 4000 Liѐge, Belgium.
| | - Anna Jurado
- University of Liѐge, ArGEnCo, Hydrogeology and Environmental Geology, Aquapôle, -B52/3 Sart-Tilman, 4000 Liѐge, Belgium
| | | | - Kay Knӧller
- Department of Catchment Hydrology, UFZ Helmholtz - Centre for Environmental Research, Germany
| | - Serge Brouyѐre
- University of Liѐge, ArGEnCo, Hydrogeology and Environmental Geology, Aquapôle, -B52/3 Sart-Tilman, 4000 Liѐge, Belgium
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Zuo R, Jin S, Chen M, Guan X, Wang J, Zhai Y, Teng Y, Guo X. In-situ study of migration and transformation of nitrogen in groundwater based on continuous observations at a contaminated desert site. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 211:39-48. [PMID: 29551242 DOI: 10.1016/j.jconhyd.2018.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 02/04/2018] [Accepted: 03/02/2018] [Indexed: 06/08/2023]
Abstract
The objective of this study was to explore the controlling factors on the migration and transformation of nitrogenous wastes in groundwater using long-term observations from a contaminated site on the southwestern edge of the Tengger Desert in northwestern China. Contamination was caused by wastewater discharge rich in ammonia. Two long-term groundwater monitoring wells (Wells 1# and 2#) were constructed, and 24 water samples were collected. Five key indicators were tested: ammonia, nitrate, nitrite, dissolved oxygen, and manganese. A numerical method was used to simulate the migration process and to determine the migration stage of the main pollutant plume in groundwater. The results showed that at Well 1# the nitrogenous waste migration process had essentially been completed, while at Well 2# ammonia levels were still rising and gradually transitioning to a stable stage. The differences for Well 1# and Well 2# were primarily caused by differences in groundwater flow. The change in ammonia concentration was mainly controlled by the migration of the pollution plume under nitrification in groundwater. The nitrification rate was likely affected by changes in dissolved oxygen and potentially manganese.
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Affiliation(s)
- Rui Zuo
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China.
| | - Shuhe Jin
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Minhua Chen
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Xin Guan
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Jinsheng Wang
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Yuanzheng Zhai
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Yanguo Teng
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
| | - Xueru Guo
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China
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Isotopic overprinting of nitrification on denitrification as a ubiquitous and unifying feature of environmental nitrogen cycling. Proc Natl Acad Sci U S A 2016; 113:E6391-E6400. [PMID: 27702902 DOI: 10.1073/pnas.1601383113] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Natural abundance nitrogen and oxygen isotopes of nitrate (δ15NNO3 and δ18ONO3) provide an important tool for evaluating sources and transformations of natural and contaminant nitrate (NO3-) in the environment. Nevertheless, conventional interpretations of NO3- isotope distributions appear at odds with patterns emerging from studies of nitrifying and denitrifying bacterial cultures. To resolve this conundrum, we present results from a numerical model of NO3- isotope dynamics, demonstrating that deviations in δ18ONO3 vs. δ15NNO3 from a trajectory of 1 expected for denitrification are explained by isotopic over-printing from coincident NO3- production by nitrification and/or anammox. The analysis highlights two driving parameters: (i) the δ18O of ambient water and (ii) the relative flux of NO3- production under net denitrifying conditions, whether catalyzed aerobically or anaerobically. In agreement with existing analyses, dual isotopic trajectories >1, characteristic of marine denitrifying systems, arise predominantly under elevated rates of NO2- reoxidation relative to NO3- reduction (>50%) and in association with the elevated δ18O of seawater. This result specifically implicates aerobic nitrification as the dominant NO3- producing term in marine denitrifying systems, as stoichiometric constraints indicate anammox-based NO3- production cannot account for trajectories >1. In contrast, trajectories <1 comprise the majority of model solutions, with those representative of aquifer conditions requiring lower NO2- reoxidation fluxes (<15%) and the influence of the lower δ18O of freshwater. Accordingly, we suggest that widely observed δ18ONO3 vs. δ15NNO3 trends in freshwater systems (<1) must result from concurrent NO3- production by anammox in anoxic aquifers, a process that has been largely overlooked.
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9
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Smith RL, Böhlke JK, Song B, Tobias CR. Role of Anaerobic Ammonium Oxidation (Anammox) in Nitrogen Removal from a Freshwater Aquifer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:12169-12177. [PMID: 26401911 DOI: 10.1021/acs.est.5b02488] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Anaerobic ammonium oxidation (anammox) couples the oxidation of ammonium with the reduction of nitrite, producing N2. The presence and activity of anammox bacteria in groundwater were investigated at multiple locations in an aquifer variably affected by a large, wastewater-derived contaminant plume. Anammox bacteria were detected at all locations tested using 16S rRNA gene sequencing and quantification of hydrazine oxidoreductase (hzo) gene transcripts. Anammox and denitrification activities were quantified by in situ (15)NO2(-) tracer tests along anoxic flow paths in areas of varying ammonium, nitrate, and organic carbon abundances. Rates of denitrification and anammox were determined by quantifying changes in (28)N2, (29)N2, (30)N2, (15)NO3(-), (15)NO2(-), and (15)NH4(+) with groundwater travel time. Anammox was present and active in all areas tested, including where ammonium and dissolved organic carbon concentrations were low, but decreased in proportion to denitrification when acetate was added to increase available electron supply. Anammox contributed 39-90% of potential N2 production in this aquifer, with rates on the order of 10 nmol N2-N L(-1) day(-1). Although rates of both anammox and denitrification during the tracer tests were low, they were sufficient to reduce inorganic nitrogen concentrations substantially during the overall groundwater residence times in the aquifer. These results demonstrate that anammox activity in groundwater can rival that of denitrification and may need to be considered when assessing nitrogen mass transport and permanent loss of fixed nitrogen in aquifers.
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Affiliation(s)
- Richard L Smith
- National Research Program, U.S. Geological Survey , 3215 Marine Street, Boulder, Colorado 80303, United States
| | - J K Böhlke
- National Research Program, U.S. Geological Survey , 431 National Center, Reston, Virginia 20192, United States
| | - Bongkeun Song
- Virginia Institute of Marine Science, College of William and Mary , P.O. Box 1346, Gloucester Point, Virginia 23062, United States
| | - Craig R Tobias
- Department of Marine Sciences, University of Connecticut , 1080 Shennecossett Road, Groton, Connecticut 06340, United States
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Barber LB, Hladik ML, Vajda AM, Fitzgerald KC, Douville C. Impact of wastewater infrastructure upgrades on the urban water cycle: Reduction in halogenated reaction byproducts following conversion from chlorine gas to ultraviolet light disinfection. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 529:264-74. [PMID: 26025637 DOI: 10.1016/j.scitotenv.2015.04.112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 04/28/2015] [Accepted: 04/28/2015] [Indexed: 05/24/2023]
Abstract
The municipal wastewater treatment facility (WWTF) infrastructure of the United States is being upgraded to expand capacity and improve treatment, which provides opportunities to assess the impact of full-scale operational changes on water quality. Many WWTFs disinfect their effluent prior to discharge using chlorine gas, which reacts with natural and synthetic organic matter to form halogenated disinfection byproducts (HDBPs). Because HDBPs are ubiquitous in chlorine-disinfected drinking water and have adverse human health implications, their concentrations are regulated in potable water supplies. Less is known about the formation and occurrence of HDBPs in disinfected WWTF effluents that are discharged to surface waters and become part of the de facto wastewater reuse cycle. This study investigated HDBPs in the urban water cycle from the stream source of the chlorinated municipal tap water that comprises the WWTF inflow, to the final WWTF effluent disinfection process before discharge back to the stream. The impact of conversion from chlorine-gas to low-pressure ultraviolet light (UV) disinfection at a full-scale (68,000 m(3) d(-1) design flow) WWTF on HDBP concentrations in the final effluent was assessed, as was transport and attenuation in the receiving stream. Nutrients and trace elements (boron, copper, and uranium) were used to characterize the different urban source waters, and indicated that the pre-upgrade and post-upgrade water chemistry was similar and insensitive to the disinfection process. Chlorinated tap water during the pre-upgrade and post-upgrade samplings contained 11 (mean total concentration=2.7 μg L(-1); n=5) and 10 HDBPs (mean total concentration=4.5 μg L(-1)), respectively. Under chlorine-gas disinfection conditions 13 HDBPs (mean total concentration=1.4 μg L(-1)) were detected in the WWTF effluent, whereas under UV disinfection conditions, only one HDBP was detected. The chlorinated WWTF effluent had greater relative proportions of nitrogenous, brominated, and iodinated HDBPs than the chlorinated tap water. Conversion of the WWTF to UV disinfection reduced the loading of HDBPs to the receiving stream by >90%.
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Affiliation(s)
- Larry B Barber
- U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303, United States
| | - Michelle L Hladik
- U.S. Geological Survey, 6000 J Street Placer Hall, Sacramento, CA 95819, United States
| | - Alan M Vajda
- University of Colorado, Department of Integrative Biology, CB 171, Denver, CO 80217, United States
| | - Kevin C Fitzgerald
- U.S. Geological Survey, 3215 Marine St., Boulder, CO 80303, United States; AECOM, 500 West Jefferson St., Ste. 1600, Louisville, KY 40202, United States
| | - Chris Douville
- City of Boulder, 4049 75th Street, Boulder, CO 80301, United States
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Opitz S, Küsel K, Spott O, Totsche KU, Herrmann M. Oxygen availability and distance to surface environments determine community composition and abundance of ammonia-oxidizing prokaroytes in two superimposed pristine limestone aquifers in the Hainich region, Germany. FEMS Microbiol Ecol 2014; 90:39-53. [PMID: 24953994 DOI: 10.1111/1574-6941.12370] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/30/2014] [Accepted: 06/11/2014] [Indexed: 01/27/2023] Open
Abstract
We followed the abundance and compared the diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the groundwater of two superimposed pristine limestone aquifers located in the Hainich region (Thuringia, Germany) over 22 months. Groundwater obtained from the upper aquifer (12 m depth) was characterized by low oxygen saturation (0-20%) and low nitrate concentrations (0-20 μM), contrasting with 50-80% oxygen saturation and 40-200 μM nitrate in the lower aquifer (48 m and 88 m depth). Quantitative PCR targeting bacterial and archaeal amoA and 16S rRNA genes suggested a much higher ammonia oxidizer fraction in the lower aquifer (0.4-7.8%) compared with the upper aquifer (0.01-0.29%). In both aquifers, AOB communities were dominated by one phylotype related to Nitrosomonas ureae, while AOA communities were more diverse. Multivariate analysis of amoA DGGE profiles revealed a stronger temporal variation of AOA and AOB community composition in the upper aquifer, pointing to a stronger influence of surface environments. Parallel fluctuations of AOA, AOB, and total microbial abundance suggested that hydrological factors (heavy rain falls, snow melt) rather than specific physicochemical parameters were responsible for the observed community dynamics.
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Affiliation(s)
- Sebastian Opitz
- Aquatic Geomicrobiology, Institute of Ecology, Friedrich Schiller University Jena, Jena, Germany
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12
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Barnes RT, Smith RL, Aiken GR. Linkages between denitrification and dissolved organic matter quality, Boulder Creek watershed, Colorado. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jg001749] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Fox PM, Kent DB, Davis JA. Redox transformations and transport of cesium and iodine (-1, 0, +5) in oxidizing and reducing zones of a sand and gravel aquifer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:1940-1946. [PMID: 20170159 DOI: 10.1021/es902865s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Tracer tests were performed in distinct biogeochemical zones of a sand and gravel aquifer in Cape Cod, MA, to study the redox chemistry (I) and transport (Cs, I) of cesium and iodine in a field setting. Injection of iodide (I(-)) into an oxic zone of the aquifer resulted in oxidation of I(-) to molecular iodine (I(2)) and iodate (10(3)(-)) over transport distances of several meters. Oxidation is attributed to Mn-oxides present in the sediment Transport of injected 10(3)(-) and Cs(+) was retarded in the mildly acidic oxic zone, with retardation factors of 1.6-1.8 for 10(3)(-) and 2.3-4.4 for Cs. Cs retardation was likely due to cation exchange reactions. Injection of 10(3)(-) into a Fe-reducing zone of the aquifer resulted in rapid and complete reduction to I(-) within 3 m of transport. Then on conservative behavior of Cs and I observed during the tracer tests underscores the necessity of taking the redox chemistry of I as well as sorption properties of I species and Cs into account when predicting transport of radionuclides (e.g., (129)I and (137)Cs) in the environment.
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Affiliation(s)
- Patricia M Fox
- U.S. Geological Survey, 345 Middlefield Road, MS 496, Menlo Park, California 94025, USA.
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Barber LB, Keefe SH, Leblanc DR, Bradley PM, Chapelle FH, Meyer MT, Loftin KA, Kolpin DW, Rubio F. Fate of sulfamethoxazole, 4-nonylphenol, and 17beta-estradiol in groundwater contaminated by wastewater treatment plant effluent. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:4843-4850. [PMID: 19673274 DOI: 10.1021/es803292v] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Organic wastewater contaminants (OWCs) were measured in samples collected from monitoring wells located along a 4.5-km transect of a plume of groundwater contaminated by 60 years of continuous rapid infiltration disposal of wastewater treatment plant effluent. Fifteen percent of the 212 OWCs analyzed were detected, including the antibiotic sulfamethoxazole (SX), the nonionic surfactant degradation product 4-nonylphenol (NP), the solvent tetrachloroethene (PCE), and the disinfectant 1,4-dichlorobenzene (DCB). Comparison of the 2005 sampling results to data collected from the same wells in 1985 indicates that PCE and DCB are transported more rapidly in the aquiferthan NP, consistent with predictions based on compound hydrophobicity. Natural gradient in situ tracer experiments were conducted to evaluate the subsurface behavior of SX, NP, and the female sex hormone 17beta-estradiol (E2) in two oxic zones in the aquifer: (1) a downgradient transition zone at the interface between the contamination plume and the overlying uncontaminated groundwater and (2) a contaminated zone located beneath the infiltration beds, which have not been loaded for 10 years. In both zones, breakthrough curves for the conservative tracer bromide (Br-) and SX were nearly coincident, whereas NP and E2 were retarded relative to Br- and showed mass loss. Retardation was greater in the contaminated zone than in the transition zone. Attenuation of NP and E2 in the aquifer was attributed to biotransformation, and oxic laboratory microcosm experiments using sediments from the transition and contaminated zones show that uniform-ring-labeled 14C 4-normal-NP was biodegraded more rapidly 130-60% recovered as 14CO2 in 13 days) than 4-14C E2 (20-90% recovered as 14CO2 in 54 days). There was little difference in mineralization potential between sites.
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Affiliation(s)
- Larry B Barber
- U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, USA.
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15
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Smith RL, Repert DA, Hart CP. Geochemistry of inorganic nitrogen in waters released from coal-bed natural gas production wells in the Powder River Basin, Wyoming. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:2348-2354. [PMID: 19452885 DOI: 10.1021/es802478p] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Water originating from coal-bed natural gas (CBNG) production wells typically contains ammonium and is often disposed via discharge to ephemeral channels. A study conducted in the Powder River Basin, Wyoming, documented downstream changes in CBNG water composition, emphasizing nitrogen-cycling processes and the fate of ammonium. Dissolved ammonium concentrations from 19 CBNG discharge points ranged from 95 to 527 microM. Within specific channels, ammonium concentrations decreased with transport distance, with subsequent increases in nitrite and nitrate concentrations. Removal efficiency, or uptake, oftotal dissolved inorganic nitrogen (DIN) varied between channel types. DIN uptake was greater in the gentle-sloped, vegetated channel as compared to the incised, steep, and sparsely vegetated channel and was highly correlated with diel patterns of incident light and dissolved oxygen concentration. In a larger main channel with multiple discharge inputs (n=13), DIN concentrations were >300 microM, with pH > 8.5, after 5 km of transport. Ammonium represented 25-30% of the large-channel DIN, and ammonium concentrations remained relatively constant with time, with only a weak diel pattern evident. In July 2003, the average daily large-channel DIN load was 23 kg N day(-1) entering the Powder River, an amount which substantially increased the total Powder River DIN load after the channel confluence. These results suggest that CBNG discharge may be an important source of DIN to western watersheds, at least at certain times of the year, and that net oxidation and/or removal is dependent upon the extent of contact with sediment and biomass, type of drainage channel, and time of day.
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Affiliation(s)
- Richard L Smith
- U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, USA.
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Lorah MM, Cozzarelli IM, Böhlke JK. Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume. JOURNAL OF CONTAMINANT HYDROLOGY 2009; 105:99-117. [PMID: 19136178 DOI: 10.1016/j.jconhyd.2008.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 10/29/2008] [Accepted: 11/03/2008] [Indexed: 05/27/2023]
Abstract
The biogeochemistry at the interface between sediments in a seasonally ponded wetland (slough) and an alluvial aquifer contaminated with landfill leachate was investigated to evaluate factors that can effect natural attenuation of landfill leachate contaminants in areas of groundwater/surface-water interaction. The biogeochemistry at the wetland-alluvial aquifer interface differed greatly between dry and wet conditions. During dry conditions (low water table), vertically upward discharge was focused at the center of the slough from the fringe of a landfill-derived ammonium plume in the underlying aquifer, resulting in transport of relatively low concentrations of ammonium to the slough sediments with dilution and dispersion as the primary attenuation mechanism. In contrast, during wet conditions (high water table), leachate-contaminated groundwater discharged upward near the upgradient slough bank, where ammonium concentrations in the aquifer where high. Relatively high concentrations of ammonium and other leachate constituents also were transported laterally through the slough porewater to the downgradient bank in wet conditions. Concentrations of the leachate-associated constituents chloride, ammonium, non-volatile dissolved organic carbon, alkalinity, and ferrous iron more than doubled in the slough porewater on the upgradient bank during wet conditions. Chloride, non-volatile dissolved organic carbon (DOC), and bicarbonate acted conservatively during lateral transport in the aquifer and slough porewater, whereas ammonium and potassium were strongly attenuated. Nitrogen isotope variations in ammonium and the distribution of ammonium compared to other cations indicated that sorption was the primary attenuation mechanism for ammonium during lateral transport in the aquifer and the slough porewater. Ammonium attenuation was less efficient, however, in the slough porewater than in the aquifer and possibly occurred by a different sorption mechanism. A stoichiometrically balanced increase in magnesium concentration with decreasing ammonium and potassium concentrations indicated that cation exchange was the sorption mechanism in the slough porewater. Only a partial mass balance could be determined for cations exchanged for ammonium and potassium in the aquifer, indicating that some irreversible sorption may be occurring. Although wetlands commonly are expected to decrease fluxes of contaminants in riparian environments, enhanced attenuation of the leachate contaminants in the slough sediment porewater compared to the aquifer was not observed in this study. The lack of enhanced attenuation can be attributed to the fact that the anoxic plume, comprised largely of recalcitrant DOC and reduced inorganic constituents, interacted with anoxic slough sediments and porewaters, rather than encountering a change in redox conditions that could cause transformation reactions. Nevertheless, the attenuation processes in the narrow zone of groundwater/surface-water interaction were effective in reducing ammonium concentrations by a factor of about 3 during lateral transport across the slough and by a factor of 2 to 10 before release to the surface water. Slough porewater geochemistry also indicated that the slough could be a source of sulfate in dry conditions, potentially providing a terminal electron acceptor for natural attenuation of organic compounds in the leachate plume.
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Affiliation(s)
- Michelle M Lorah
- U.S. Geological Survey, 5522 Research Park Drive, Baltimore, MD 21228, USA.
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Miller DN, Smith RL. Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria. JOURNAL OF CONTAMINANT HYDROLOGY 2009; 103:182-193. [PMID: 19059672 DOI: 10.1016/j.jconhyd.2008.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 09/26/2008] [Accepted: 10/25/2008] [Indexed: 05/27/2023]
Abstract
Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2 (>300 microM) and NH4+ (51-800 microM). The second site was 2.5 km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O2, NH4+, and NO3- (0-300, 0-500, and 100-200 microM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350 g(-1) and 33 to 35,000 g(-1), respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.
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Affiliation(s)
- Daniel N Miller
- U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, United States.
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18
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Smith RL, Yoshinari T. Occurrence and turnover of nitric oxide in a nitrogen-impacted sand and gravel aquifer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8245-8251. [PMID: 19068801 DOI: 10.1021/es801290v] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Little is known about nitric oxide (NO) production or consumption in the subsurface, an environment which may be conducive to NO accumulation. A study conducted in a nitrogen-contaminated aquifer on Cape Cod, Massachusetts assessed the occurrence and turnover of NO within a contaminant plume in which nitrification and denitrification were known to occur. NO (up to 8.6 nM) was detected in restricted vertical zones located within a nitrate (NO3-) gradient and characterized by low dissolved oxygen (< 10 microM). NO concentrations correlated best with nitrite (NO2-) (up to 35 microM), but nitrous oxide (N2O) (up to 1 microM) also was present. Single-well injection tests were used to determine NO production and consumption in situ within these zones. First-order rate constants for NO consumption were similar (0.05-0.08 h(-1)) at high and low (260 and 10 nM) NO concentrations, suggesting a turnover time at in situ concentrations of 10-20 h. Tracer tests with 15N[NO] demonstrated that oxidation to 15N[NO2-] occurred only during the initial stages, but after 4 h reduction to 15N[N2O] was the primary reaction product. Added NO2- (31 microM) or NO3- (53 microM) resulted in a linear NO accumulation at 2.4 and 1.0 nM h(-1) for the first 6 h of in situ tests. These results suggest that NO was primarily produced by denitrification within this aquifer.
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Affiliation(s)
- Richard L Smith
- U.S. Geological Survey, 3215 Marine Street, Suite E127, Boulder, Colorado 80303, USA.
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Kaushal SS, Groffman PM, Mayer PM, Striz E, Gold AJ. Effects of stream restoration on denitrification in an urbanizing watershed. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2008; 18:789-804. [PMID: 18488635 DOI: 10.1890/07-1159.1] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Increased delivery of nitrogen due to urbanization and stream ecosystem degradation is contributing to eutrophication in coastal regions of the eastern United States. We tested whether geomorphic restoration involving hydrologic "reconnection" of a stream to its floodplain could increase rates of denitrification at the riparian-zone-stream interface of an urban stream in Baltimore, Maryland. Rates of denitrification measured using in situ 15N tracer additions were spatially variable across sites and years and ranged from undetectable to >200 microg N x (kg sediment)(-1) x d(-1). Mean rates of denitrification were significantly greater in the restored reach of the stream at 77.4 +/- 12.6 microg N x kg(-1) x d(-1) (mean +/- SE) as compared to the unrestored reach at 34.8 +/- 8.0 microg N x kg(-1) x d(-1). Concentrations of nitrate-N in groundwater and stream water in the restored reach were also significantly lower than in the unrestored reach, but this may have also been associated with differences in sources and hydrologic flow paths. Riparian areas with low, hydrologically "connected" streambanks designed to promote flooding and dissipation of erosive force for storm water management had substantially higher rates of denitrification than restored high "nonconnected" banks and both unrestored low and high banks. Coupled measurements of hyporheic groundwater flow and in situ denitrification rates indicated that up to 1.16 mg NO3(-)-N could be removed per liter of groundwater flow through one cubic meter of sediment at the riparian-zone-stream interface over a mean residence time of 4.97 d in the unrestored reach, and estimates of mass removal of nitrate-N in the restored reach were also considerable. Mass removal of nitrate-N appeared to be strongly influenced by hydrologic residence time in unrestored and restored reaches. Our results suggest that stream restoration designed to "reconnect" stream channels with floodplains can increase denitrification rates, that there can be substantial variability in the efficacy of stream restoration designs, and that more work is necessary to elucidate which designs can be effective in conjunction with watershed strategies to reduce nitrate-N sources to streams.
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Affiliation(s)
- Sujay S Kaushal
- University of Maryland, Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, Maryland 21532, USA.
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Subsurface microbial diversity in deep-granitic-fracture water in Colorado. Appl Environ Microbiol 2007; 74:143-52. [PMID: 17981950 DOI: 10.1128/aem.01133-07] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a >1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (Gallionella spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that Nitrosomonadales dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by Firmicutes, Proteobacteria, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This "Henderson candidate division" dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions Proteobacteria (primarily the family Ralstoniaceae) and Firmicutes. Sequences grouping within Ralstoniaceae were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems.
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Harris SH, Smith RL, Suflita JM. In situ hydrogen consumption kinetics as an indicator of subsurface microbial activity. FEMS Microbiol Ecol 2007; 60:220-8. [PMID: 17439588 DOI: 10.1111/j.1574-6941.2007.00286.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
There are few methods available for broadly assessing microbial community metabolism directly within a groundwater environment. In this study, hydrogen consumption rates were estimated from in situ injection/withdrawal tests conducted in two geochemically varying, contaminated aquifers as an approach towards developing such a method. The hydrogen consumption first-order rates varied from 0.002 nM h(-1) for an uncontaminated, aerobic site to 2.5 nM h(-1) for a contaminated site where sulfate reduction was a predominant process. The method could accommodate the over three orders of magnitude range in rates that existed between subsurface sites. In a denitrifying zone, the hydrogen consumption rate (0.02 nM h(-1)) was immediately abolished in the presence of air or an antibiotic mixture, suggesting that such measurements may also be sensitive to the effects of environmental perturbations on field microbial activities. Comparable laboratory determinations with sediment slurries exhibited hydrogen consumption kinetics that differed substantially from the field estimates. Because anaerobic degradation of organic matter relies on the rapid consumption of hydrogen and subsequent maintenance at low levels, such in situ measures of hydrogen turnover can serve as a key indicator of the functioning of microbial food webs and may be more reliable than laboratory determinations.
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Affiliation(s)
- Steve H Harris
- Department of Botany and Microbiology, Institute for Energy and the Environment, The University of Oklahoma, Norman, OK, USA.
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