Article
Agricultural Engineering
Xiaodan Zhao, Jie Jiang, Zhen Zhou, Yue Zheng, Yanjun Shao, Yi Zuo, Yuqing Ren, Ying An
Summary: This study investigated the effects of hydraulic retention time of anaerobic side-stream reactors on nitrogen removal in four anoxic/oxic membrane bioreactors. The results showed that upgrading with anaerobic side-stream reactors and carriers can enhance nitrogen removal efficiency by increasing denitrifying bacteria and secondary substrate release. Additionally, metagenomic analysis revealed higher abundances of genes related to nitrogen consumption processes in the upgraded reactors, confirming their pivotal roles in nitrogen metabolism.
BIORESOURCE TECHNOLOGY
(2021)
Article
Chemistry, Physical
Zhiliang Chen, Lihang An, Hang Wei, Jianqiang Zhang, Qi Zou, Mengqiang Sun, Ling Huang, Minchao Liu
Summary: The study found that the addition of nitrate can accelerate the reduction of soil Eh, inhibit dissimilatory iron reduction, and promote arsenic speciation transformation, making it an effective amendment for arsenic immobilization in paddy soils.
SURFACES AND INTERFACES
(2021)
Review
Chemistry, Multidisciplinary
Xiaoxuan Yang, Shreya Mukherjee, Thomas O'Carroll, Yang Hou, Meenesh R. Singh, Joseph A. Gauthier, Gang Wu
Summary: Unrestrained anthropogenic activities disrupt the global natural nitrogen cycle, leading to energy and environmental issues. Electrocatalytic nitrogen transformation offers a feasible and promising strategy for a sustainable nitrogen economy. By synergistically combining multiple nitrogen reactions, efficient renewable energy storage and conversion, nitrogen balance restoration, and environmental crisis remediation can be achieved.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Ecology
Lauren M. Seyler, Elizabeth Trembath-Reichert, Benjamin J. Tully, Julie A. Huber
Summary: The microbial community in the oceanic crustal aquifer plays a crucial role in organic carbon oxidation, showing activity, metabolic flexibility, and the ability to adapt to low oxygen conditions, with different anaerobic processes at varying depths within the aquifer.
Article
Microbiology
Sada Egenriether, Robert Sanford, Wendy H. H. Yang, Angela D. Kent
Summary: Assessments of the soil microbiome provide valuable insight to ecosystem function due to the integral role microorganisms play in biogeochemical cycling of carbon and nutrients. The study compared heuristic OTU clustering and true hierarchical OTU clustering methods on two nitrogen cycling genes and found that hierarchical method outperformed heuristic method for a more diverse gene, nrfA. These findings suggest that care should be exercised in choosing clustering methods to ensure accurate analysis in microbiome studies.
FRONTIERS IN MICROBIOLOGY
(2022)
Article
Environmental Sciences
Yuecheng She, Xin Qi, Xiaodong Xin, Yanqing He, Wei Wang, Zhengkui Li
Summary: Microbial mechanisms play a crucial role in nitrate reduction in sediments of aquaculture ponds, with denitrification being the dominant process. The activities and composition of microbial communities in aquaculture ponds are influenced by the availability of carbon and nitrogen substrates, while autotrophic denitrifiers control the microbial network in natural freshwater sediments.
ENVIRONMENTAL RESEARCH
(2023)
Article
Geochemistry & Geophysics
Yaoxuan Chen, Xiaosi Su, Yuyu Wan, Hang Lyu, Weihong Dong, Yakun Shi, Yiwu Zhang
Summary: River eutrophication and nitrogen pollution pose a potential threat to groundwater quality in riverbank filtration systems. This study used hydrogeochemical and stable isotope tracing techniques to investigate the geochemical reactions controlling nitrogen migration and transformation during riverbank filtration in a typical site in NE China. The results revealed that mixing, adsorption, organic nitrogen mineralization, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) are the main geochemical reactions. Denitrification primarily occurs close to the riverbed surface and accounts for NO3- attenuation, while DNRA is more active at a certain depth and plays a significant role in NH4+ enrichment.
APPLIED GEOCHEMISTRY
(2022)
Article
Engineering, Environmental
Shanyun Wang, Xiaomin Wang, Yingying Jiang, Chang Han, Mike S. M. Jetten, Lorenz Schwark, Guibing Zhu
Summary: The discovery of complete ammonia oxidation (comammox) has changed our understanding of nitrification, and fringe soils in riparian ecosystems may serve as hotspots for comammox activity.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2021)
Article
Microbiology
Stilianos Louca, Gordon T. Taylor, Yrene M. Astor, Kristen N. Buck, Frank E. Muller-Karger
Summary: When population dynamics and reaction kinetics operate at much shorter time scales than physical mixing processes, the need for unknown population dynamical, physiological and reaction-kinetic parameters and uncertainties in species composition can be eliminated. In this 'fast-reaction-transport' (FRT) limit, accurate predictions can be made based on chemical boundary conditions, physical mixing processes and reaction stoichiometries without knowledge of species composition, physiology or population/reaction kinetic parameters. Our findings suggest that microbial processes in poorly mixed water columns and sediments are largely transport limited and thus predictable regardless of species composition, population dynamics and kinetics.
ENVIRONMENTAL MICROBIOLOGY
(2023)
Article
Environmental Sciences
Feng Sun, Qinghui Deng, Xiaowen Li, Mengjuan Tang, Xufa Ma, Xiuyun Cao, Yiyong Zhou, Chunlei Song
Summary: The study found that high organic carbon content in matrix facilitated dissimilatory nitrate reduction to ammonium (DNRA) over denitrification (DEN), while low organic carbon content promoted DEN. It was also observed that using corn cob as OC source in biofilters was more effective than bagasse due to slow and continuous release of organic carbon. Choosing suitable OC source and regulating its dosage are crucial for enhancing nitrate removal and reducing ammonium accumulation in biofilters.
Article
Environmental Sciences
Ke Zhang, Xiangling Wu, Jia Chen, Wei Wang, Hongbing Luo, Wei Chen, Dandan Ma, Xiaochan An, Zhaolan Wei
Summary: This study proposed an effective method to reduce methane emissions from constructed wetlands by introducing Mn-dependent anaerobic oxidation of methane (Mn-AOM) and microbial fuel cell (MFC) technology. The results showed that combining biological methods and bioelectrochemical methods can more effectively control methane emissions from constructed wetlands. Using Mn ore as the matrix and operating MFC effectively reduced methane emissions from constructed wetlands, with higher COD removal rate obtained in CW-MFC (Mn) during the 200 days of operation.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2021)
Article
Agricultural Engineering
Xuejiao Qiao, Chenkun Fu, Yizhen Chen, Fang Fang, Yaoyu Zhang, Lingyun Ding, Kai Yang, Baozhu Pan, Nan Xu, Ke Yu, Huchun Tao, Lijuan Zhang
Summary: It was found that 20 μg/L of fluoroquinolones promoted the nitrogen removal performance of anammox microorganisms and removed 36-51% of the drugs. Metabolomics and genome-resolved metagenomic analysis revealed enhanced carbon fixation, purine and pyrimidine metabolism, protein generation, and transmembrane transport in anammox bacteria and symbiotic bacteria in response to 20 μg/L of fluoroquinolones. Consequently, hydrazine dehydrogenation, nitrite reduction, and ammonium assimilation were bolstered, improving the nitrogen removal efficiency of the anammox system.
BIORESOURCE TECHNOLOGY
(2023)
Article
Agricultural Engineering
Shiyang Zhang, Longqu Xiao, Zhiwei Tang, Xiangling Zhang, Zhi Wang
Summary: This study investigated the fluctuating profiles of physicochemical and microbial characterizations along different filling heights of continuously up-flow solid-phase denitrification columns packed with PCL. It was found that both the PCL filling area and non-filling area significantly contributed to treatment performance, with denitrification mainly occurring near the bottom of the filling column. Nitrate showed high removal rates, while nitrite and ammonium displayed weak accumulation in final effluents.
BIORESOURCE TECHNOLOGY
(2022)
Article
Agricultural Engineering
Lilong Yan, Caixu Wang, Jishuang Jiang, Shuang Liu, Yaoqi Zheng, Mengya Yang, Ying Zhang
Summary: A new type of aerobic nitrification-reducing bacteria, Pseudomonas XS-18, was isolated and studied for its nitrate removal capacity and alkali tolerance mechanism. XS-18 demonstrated high efficiency in nitrate removal and conversion in strong alkaline conditions, showing potential for application in alkaline wastewater treatment.
BIORESOURCE TECHNOLOGY
(2022)
Article
Environmental Sciences
Tekle Tafese Fida, Mohita Sharma, Yin Shen, Gerrit Voordouw
Summary: Bisulfite is used as an oxygen scavenger in waters for oil production to prevent pipeline corrosion. Analysis showed increased concentrations of ammonium, sulfate, and nitrite. Sulfuricurvum bacteria were found to dominate the microbial community and could oxidize bisulfite while reducing nitrate to form sulfate and nitrite. The study suggests an alternative injection procedure using bisulfite and nitrate to maintain the oxygen scavenger function and inhibit sulfide formation.
Article
Ecology
Elliott E. White, Emily A. Ury, Emily S. Bernhardt, Xi Yang
Summary: Coastal forested wetlands in North America have been diminishing in extent due to historic drainage and agricultural expansion. Satellite imagery analysis shows that between 1996 and 2016, there was a net loss of approximately 13,682 km² of forested coastal wetlands across the North America's Coastal Plain. Factors such as sea level rise, tropical storm landings, and watershed elevation explain most of the variation in coastal wetland deforestation extent.
Article
Environmental Sciences
Emily A. Ury, Justin P. Wright, Marcelo Ardon, Emily S. Bernhardt
Summary: The addition of marine salts in wetland soils resulted in depressed microbial respiration and dissolved organic carbon solubility, with a preferential reduction in phenolic and aromatic organic molecules in solution. The effects of marine salts on carbon mineralization rates were more pronounced in base saturated soils compared to acidic soils. Ion exchange mechanisms due to salinization indirectly affect the pH of soil solution and the solubility of organic matter.
Article
Limnology
Amanda G. DelVecchia, Spencer Rhea, Kelly S. Aho, Emily H. Stanley, Erin R. Hotchkiss, Alice Carter, Emily S. Bernhardt
Summary: Streams and rivers are major sources of greenhouse gas emissions. While our understanding of individual gas flux drivers has improved, the lack of consistently collected samples hinders our ability to analyze the interrelationship between gas concentrations and their drivers. This study analyzed a dataset collected by the National Ecological Observatory Network, providing insights into the physical and biogeochemical drivers of greenhouse gas production in 27 streams and rivers across the United States. The results show that physical drivers such as temperature, stream slope, dissolved oxygen, and total nitrogen concentration strongly influence the concentrations of CO2 and CH4, while N2O is exclusively correlated with total nitrogen concentration.
LIMNOLOGY AND OCEANOGRAPHY
(2023)
Review
Multidisciplinary Sciences
Tom J. Battin, Ronny Lauerwald, Emily S. Bernhardt, Enrico Bertuzzo, Lluis Gomez Gener, Robert O. Hall Jr, Erin R. Hotchkiss, Taylor Maavara, Tamlin M. Pavelsky, Lishan Ran, Peter Raymond, Judith A. Rosentreter, Pierre Regnier
Summary: River networks are the largest biogeochemical connection between land, ocean and atmosphere. Our understanding of the role of rivers in the global carbon cycle is limited, making it difficult to predict how global change will affect riverine carbon sequestration and greenhouse gas emissions. This review summarizes the current state of river ecosystem metabolism research and provides estimates of carbon flux from land to rivers. The study highlights the importance of a global river observing system in understanding river networks and their future evolution in the context of the global carbon budget.
Article
Environmental Sciences
Alice M. Carter, Amanda G. DelVecchia, Emily S. Bernhardt
Summary: Freshwater ecosystems are significant sources of greenhouse gases (GHGs) to the atmosphere, and low-gradient headwater streams may facilitate in situ GHG production. Our study found that stream metabolic processes, along with long water residence times and limited reaeration, contribute significantly to CO2 and CH4 fluxes in streams.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2022)
Article
Limnology
Joanna R. Blaszczak, Lauren E. Koenig, Francine H. Mejia, Lluis Gomez-Gener, Christopher L. Dutton, Alice M. Carter, Nancy B. Grimm, Judson W. Harvey, Ashley M. Helton, Matthew J. Cohen
Summary: This study reveals that hypoxia is a global issue in rivers, with a prevalence of 12.6% in sampled sites. Hypoxic events are more likely to occur at night and are influenced by river attributes rather than watershed characteristics. Warmer, smaller, and lower-gradient rivers with urban or wetland land cover show a higher likelihood of hypoxia.
LIMNOLOGY AND OCEANOGRAPHY LETTERS
(2023)
Letter
Environmental Sciences
Marcelo Ardon, Deborah A. Clark, Nicholas S. Marzolf, Alonso Ramirez, Catherine M. Pringle
Summary: A study in La Selva Biological Station showed that trees capable of biological N-fixation in tropical forests lead to higher stream nitrate concentrations compared to temperate forests. The study also found a correlation between the productivity of tropical forests and stream nitrate concentrations, as well as the influence of landscape position on this relationship.
Review
Engineering, Civil
Ashley M. Helton, Jennifer L. Morse, Elizabeth B. Sudduth, Marcelo Ardon, Raven Bier, Kristofor A. Voss, Matthew R. V. Ross, Joanna R. Blaszczak, Jessica E. Brandt, Marie Simonin, Jennifer D. Rocca, Alice Carter, Jacqueline R. Gerson, Emily A. Ury, Michael J. Vlah
Summary: In this paper, we describe the major contributions of Professor Emily Bernhardt to the hydrologic sciences. She has investigated the impacts of environmental perturbations on hydrologic dynamics and ecosystem connectivity, focusing on carbon, nutrient, and contaminant dynamics. Her research combines extensive field sampling, experimental manipulations, data harmonization, and continental to global-scale synthesis to understand the drivers and patterns of human impacts on water and elemental cycles. Her research approach explicitly considers connectivity and interfaces, making significant contributions across elemental cycles, ecosystems, watersheds, scales, and disciplines.
JOURNAL OF HYDROLOGY
(2023)
Article
Engineering, Civil
Justine A. Neville, Ryan E. Emanuel, Marcelo Ardon, Tamlin Pavelsky
Summary: Saltwater intrusion poses a widespread threat to coastal ecosystems. The effectiveness of engineered flow control structures in managing salinity varies depending on their location and design. This study highlights the importance of considering these factors when implementing new structures for freshwater management.
JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT
(2023)
Correction
Multidisciplinary Sciences
Spencer Rhea, Nicholas Gubbins, Amanda G. DelVecchia, Matthew R. V. Ross, Emily S. Bernhardt
Article
Multidisciplinary Sciences
Samantha L. Rumschlag, Michael B. Mahon, Devin K. Jones, William Battaglin, Jonny Behrens, Emily S. Bernhardt, Paul Bradley, Ethan Brown, Frederik De Laender, Ryan Hill, Stefan Kunz, Sylvia Lee, Emma Rosi, Ralf Schaefer, Travis S. Schmidt, Marie Simonin, Kelly Smalling, Kristofor Voss, Jason R. Rohr
Summary: Based on the analysis of 6131 stream sites across different land uses in the United States over a period of 27 years, it was found that macroinvertebrate density declined by 11% and richness increased by 12.2%. Insect density and richness showed even greater declines of 23.3% and 6.8%, respectively. Furthermore, there was an increasing difference in richness and composition between urban and agricultural streams compared to forested and grassland streams. Urban and agricultural streams lost disturbance-sensitive taxa and gained disturbance-tolerant taxa. These findings indicate that current stream protection and restoration efforts are insufficient to mitigate the impacts of human activities.
Article
Engineering, Environmental
Christina M. Bergemann, Astrid Avellan, Brittany G. Perrotta, Emily S. Bernhardt, Marie Simonin
Summary: This study found that seasonal fluctuations and grazers significantly affected the fate of gold nanoparticles (AuNPs). Higher temperatures in the warmer season increased dissolved organic carbon content in the water column, leading to the stabilization of gold in the water column. Additionally, snail grazing on biofilm resulted in the transfer of gold from macrophytes to the organic matter above sediments.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Water Resources
Adam B. Haynes, Martin A. Briggs, Eric Moore, Kevin Jackson, James Knighton, David M. Rey, Ashley M. Helton
Summary: Riverbank groundwater discharge faces are areas of preferential seepage exposed to air at low river flow. They represent the convergence of highly variable age and length groundwater flowpaths, with some consistency in source groundwater characteristics. A field investigation was conducted on the Farmington River, CT, using temperature-based models and multi-parameter classification to assess discharge patterns and flowpath characteristics. Shallow, local sources were found at upstream discharge faces, while downstream faces exhibited deeper and regional flowpath characteristics. Local flowpath heterogeneity also influenced larger scale flowpath characteristics.
HYDROLOGICAL PROCESSES
(2023)
Article
Limnology
Matthew N. Waters, Emily S. Bernhardt, Jacqueline R. Gerson
Summary: This study investigated the impacts of dam construction on elemental deposition in a reservoir downstream of mountaintop coal mining. The results showed that dam construction altered environmental processes of mining elements, which could have long-lasting effects on reservoir biota and downstream environments.
LAKE AND RESERVOIR MANAGEMENT
(2023)
Article
Education & Educational Research
Jolie A. L. Gareis, Erin I. Larson, Marcelo Ardon, John A. Berges, Jessica E. Brandt, Kaitlyn M. Busch, Victoria L. S. Chraibi, Elizabeth N. Gallagher, Kelly L. Hondula, Dustin W. Kincaid, Todd D. Levine, Chelsea J. Little, Emily R. Nodine, Amber M. Rock, Arial J. Shogren, Michael J. Vanni
Summary: Despite reservations from many instructors about the use of Wikipedia in academic settings, editing Wikipedia can teach students valuable writing, editing, and critical thinking skills. Wikipedia assignments can increase students' motivation and awareness of reliable scientific sources. While there are challenges in implementing these new types of assignments, resources and solutions can be provided to overcome them.
FRONTIERS IN EDUCATION
(2022)