Article
Environmental Sciences
Dongyao Sun, Jiafang Huang, Min Luo, Cheng Chen, Xue Lan, Weifang Hu
Summary: Intensive aquaculture in estuaries and coasts has led to ecological and environmental problems. Among nitrogen transformation pathways, dissimilatory nitrate reduction plays a crucial role in regulating reactive nitrogen. This study investigated the three sediment processes of nitrate reduction and found that denitrification was the dominant pathway. Environmental factors such as C and N substrates and salinity significantly influenced nitrate reduction. The nitrogen losses from denitrification and anaerobic ammonium oxidation were substantial, indicating the importance of coastal reclamation in nitrogen removal.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Environmental Sciences
Binjie Zhao, Xinshuai Li, Yang Wang, Xiang Tan, Wenhua Qi, Hongran Li, Junwei Wei, Yong You, Wenjun Shi, Quanfa Zhang
Summary: The study investigated dissimilatory nitrate reduction rates in sediments of two subtropical rivers in China, revealing varying contributions of denitrification, anammox, and DNRA in different seasons and under different levels of human disturbance. The rates were correlated with environmental factors, highlighting the importance of understanding these processes for sustaining the ecohealth of river ecosystems.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2021)
Article
Environmental Sciences
Yongkai Chang, Guoyu Yin, Lijun Hou, Min Liu, Yanling Zheng, Ping Han, Hongpo Dong, Xia Liang, Dengzhou Gao, Cheng Liu
Summary: This study investigated the rates of denitrification and anammox in coastal sediments off the north East China Sea, finding that nitrate was a critical factor influencing the ratio between coupled and uncoupled nitrogen removal, and that ammonia oxidizing bacteria may play an important role in the coupled nitrification-denitrification process. These results emphasize the importance of nitrification in nitrogen removal in coastal ecosystems.
JOURNAL OF SOILS AND SEDIMENTS
(2021)
Article
Environmental Sciences
Paraskevi Mara, Virginia P. Edgcomb, Taylor R. Sehein, David Beaudoin, Chuck Martinsen, Christina Lovely, Bridget Belcher, Rebecca Cox, Meghan Curran, Claire Farnan, Peter Giannini, Sarah Lott, Kyle Paquette, Anna Pinckney, Natalie Schafer, Tonna-Marie Surgeon-Rogers, Daniel R. Rogers
Summary: The study found that oyster aquaculture plays a positive role in the removal of nitrogen from sediments, but different farming methods show variations in gene expression related to nitrogen cycling and nitrogen gas flux. Particularly, nitrogen retention process is significantly enhanced, especially under the bottom cages.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Environmental Sciences
Manping Zhang, Jung-Chen Huang, Shanshan Sun, Muhammad Muneeb Ur Rehman, Shengbing He, Weili Zhou
Summary: Constructed wetlands are effective in removing nitrogen from water, with potential activities of DNRA, anammox, denitrification, and nitrification contributing to nitrogen removal. Planted mesocosms showed better performance in nitrogen removal compared to unplanted mesocosms, with higher values of potential activities of nitrogen-cycling pathways observed in the planted mesocosms.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Marine & Freshwater Biology
Sanni L. Aalto, Eero Asmala, Tom Jilbert, Susanna Hietanen
Summary: Coastal environments play a crucial role in regulating the transfer of nitrogen from land to sea, with variations in nitrate reduction processes between estuary and offshore archipelago environments in the Baltic Sea. The balance between denitrification and DNRA processes is influenced by the ratio of nitrate to autochthonous organic carbon, impacting the release of nitrous oxide and efficiency of nitrogen recycling in different coastal areas.
ESTUARINE COASTAL AND SHELF SCIENCE
(2021)
Article
Environmental Sciences
Fangjuan Huang, Xianbiao Lin, Kedong Yin
Summary: Dissolved inorganic nitrogen (DIN) is high in the Pearl River Estuary (PRE), and nitrate (NOx-) removal processes play a crucial role in determining its export to coastal waters. By studying surface sediments, it was found that denitrification is the major removal process, and marine-produced organic matter is the primary driver for benthic NOx- removal processes.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Environmental Sciences
Zhenzhen Teng, Xianbiao Lin
Summary: This study investigates the dynamics of sediment NOx- reduction processes in mangroves of different ages and finds that organic matter and microbial abundances are the main factors controlling nitrogen loss and retention. The conservation and restoration of mangroves can increase sediment nitrogen retention, providing more nutrients for mangrove and microorganism growth.
SCIENCE OF THE TOTAL ENVIRONMENT
(2024)
Article
Engineering, Environmental
Lijie Zhou, Bikai Zhao, Wei-Qin Zhuang
Summary: The double-edged sword effects of Dissimilatory nitrate reduction to ammonium (DNRA) bacteria on anammox bacteria were investigated. It was found that the overgrowth of DNRA bacteria had a negative impact on the nitrogen removal efficiency of anammox bacteria.
Article
Environmental Sciences
Haoming Xu, Guodong Song, Siqi Yang, Ruosi Zhu, Guiling Zhang, Sumei Liu
Summary: This study investigates benthic nitrogen cycling in the deep ocean of the Kuroshio Extension region and highlights nitrification as the predominant process and anammox as the dominant N-loss process. The findings suggest temperature and ammonium are limiting factors for deep-ocean benthic N-loss. Additionally, there is a tight coupling relationship between pelagic primary production and the benthic nitrogen cycle in the study area.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Engineering, Environmental
Jin-Long Zhuang, Xu Sun, Wei-Qi Zhao, Xu Zhang, Jia-Jia Zhou, Bing-Jie Ni, Yong-Di Liu, James P. Shapleigh, Wei Li
Summary: This study introduces an innovative reactor called iGB-A/PD, which combines granular sludge and fixed-biofilm to remove nitrogen from municipal wastewater. Compared to other A/PD systems, this reactor has higher effluent quality and nitrogen removal rate. Gene expression analysis confirms the important role of anammox bacteria in nitrogen removal and reveals high expression of other genes related to nitrogen conversion. Kinetic assays and mass flux determination show the activity and importance of different regions of the reactor in nitrogen conversion. Metagenomic analysis identifies the dominant species involved in the process.
Article
Engineering, Environmental
Junkai Gao, Guanglong Liu, Xiaowen Li, Mengjuan Tang, Xiuyun Cao, Yiyong Zhou, Chunlei Song
Summary: This study investigated the impact of organic carbon quantity and composition on nitrate reduction pathways in two basins of Lake Chaohu in Hefei City, China. It was found that the serious algal bloom in the west basin resulted in higher organic carbon accumulation and nitrate deficiency, leading to a high C/NO3--N ratio. This triggered dissimilatory nitrate reduction to ammonium (DNRA) and specific bacterial communities played a role in this process.
Article
Environmental Sciences
Song Li, Robert R. Twilley, Denise M. Poveda, Robinson W. Fulweiler
Summary: Hurricanes have a significant impact on wetland hydrodynamics, sedimentation, and vegetation structure in estuarine and coastal wetlands. This study investigated the effects of Hurricane Barry on benthic nitrogen dynamics in the Wax Lake Delta in Louisiana. The results showed that the disturbance of the hurricane was most significant at sites with higher sediment organic matter concentrations, leading to a decrease in denitrification rates and nitrate removal capacity. The disturbed site had not fully recovered three years after the hurricane. Evaluation: 7/10.
ESTUARIES AND COASTS
(2023)
Article
Agricultural Engineering
Hao Sheng, Rui Weng, Yan He, Zheng Wei, Yanmei Yang, Jinghan Chen, Minsheng Huang, Gongming Zhou
Summary: This study identified a nitrate-calcium-based pathway that accelerated the start-up of anammox. Calcium nitrate induced partial denitrification to provide nitrite for anammox, while also increasing the contribution of dissimilatory nitrate reduction to ammonium (DNRA). This mutualistic symbiosis among denitrification, DNRA, and anammox in the calcium nitrate-added systems explained the accelerated start-up of anammox.
BIORESOURCE TECHNOLOGY
(2021)
Article
Engineering, Environmental
Aomei Guan, Weixiao Qi, Qiang Peng, Jiemin Zhou, Yaohui Bai, Jiuhui Qu
Summary: The study revealed that the antibiotic sulfamethoxazole has complex effects on nitrogen reduction processes in aquatic ecosystems, altering the activities of denitrification, anammox, and dissimilatory nitrate reduction to ammonium under different environmental conditions, leading to a shift in nitrogen conversion direction.
JOURNAL OF HAZARDOUS MATERIALS
(2022)
Article
Environmental Sciences
Song Li, Alexandra Christensen, Robert R. Twilley
Article
Forestry
Andre S. Rovai, Clemente Coelho-Jr, Renato de Almeida, Marilia Cunha-Lignon, Ricardo P. Menghini, Robert R. Twilley, Gilberto Cintron-Molero, Yara Schaeffer-Novelli
Summary: Mangroves are important components of coastlines around the world, providing ecosystem services such as carbon sequestration, but detailed carbon inventories are lacking in many countries. Brazil, with the second largest mangrove area globally, lacks a detailed inventory largely due to the scarcity of comprehensive carbon assessments. Research in southeastern Brazil revealed high ecosystem-level carbon stocks and sequestration rates in the Cananeia-Iguape lagoon estuarine system.
FOREST ECOLOGY AND MANAGEMENT
(2021)
Article
Marine & Freshwater Biology
Daniel Jensen, Kyle C. Cavanaugh, Marc Simard, Alexandra Christensen, Andre Rovai, Robert Twilley
Summary: The Wax Lake Delta is an actively prograding delta in the Mississippi River Delta Plain, accumulating sediment that increases soil surface elevation and changes wetland communities as the delta develops. This study utilized high resolution imaging data to map vegetation species and types, showing changes in wetland forest species and herbaceous wetland species over a 5-year period. The research also examined plant growth patterns in different elevational zones to inform future restoration efforts in the area.
ESTUARINE COASTAL AND SHELF SCIENCE
(2021)
Article
Ecology
Andre S. Rovai, Robert R. Twilley, Edward Castaneda-Moya, Stephen R. Midway, Daniel A. Friess, Carl C. Trettin, Jacob J. Bukoski, Atticus E. L. Stovall, Paulo R. Pagliosa, Alessandra L. Fonseca, Richard A. Mackenzie, Aslan Aslan, Sigit D. Sasmito, Meriadec Sillanpaa, Thomas G. Cole, Joko Purbopuspito, Matthew W. Warren, Daniel Murdiyarso, Wolfram Mofu, Sahadev Sharma, Pham Hong Tinh, Pablo Riul
Summary: Mangrove wetlands have diverse tree communities spanning broad geographical gradients. The study found that factors such as latitudinal variation, allometric scaling relationships, and species composition do not significantly impact mangrove forest structure and biomass allocation. Regional climate and hydroperiod play a greater role in controlling biomass accumulation across global geographical gradients.
GLOBAL ECOLOGY AND BIOGEOGRAPHY
(2021)
Article
Limnology
Song Li, Robert R. Twilley, Aixin Hou
Summary: The study revealed that increasing nitrate concentrations shifted the dominance of N-2 fixation to denitrification in benthic nitrogen cycling. While high nitrate levels reduced N-2 fixation rates, they did not completely inhibit N-2 fixation, especially in sites with higher sediment organic matter concentrations.
LIMNOLOGY AND OCEANOGRAPHY
(2021)
Article
Environmental Sciences
Robert R. Twilley, Silke Rick, Daniel C. Bond, Justin Baker
Summary: Benthic fluxes of dissolved nutrients were measured in subtidal sediments and intertidal soils associated with river-pulse events from the Mississippi River via a diversion structure at Caernarvon, LA. Intertidal habitats were found to remove a higher percentage of NO3- compared to subtidal habitats, especially at higher water temperatures and diversion discharge rates. River diversion operations have significant ecosystem design considerations for reducing the negative impacts of eutrophication in downstream coastal waters.
Article
Environmental Sciences
Alicia Sendrowski, Edward Castaneda-Moya, Robert Twilley, Paola Passalacqua
Summary: This study analyzed the influence of various external and internal drivers on nitrate variability in a coastal deltaic wetland in Louisiana, identifying that external drivers work together to influence nitrate transport and that patterns of hydrological and sediment connectivity change over time, influencing the emergence of functional zones.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2021)
Article
Marine & Freshwater Biology
Andre S. Rovai, Robert R. Twilley, Alexandra Christensen, Annabeth McCall, Daniel J. Jensen, Gregg A. Snedden, James T. Morris, John A. Cavell
Summary: The study reveals that Colocasia esculenta, a species of tidal freshwater marsh, is able to cope with longer hydroperiods caused by river sediment diversions, and even increase its biomass. This is in contrast to previous studies conducted in brackish and saline settings where longer hydroperiods had negative effects on biomass accumulation.
ESTUARINE COASTAL AND SHELF SCIENCE
(2022)
Article
Geography, Physical
Azure E. Bevington, Robert R. Twilley, Charles E. Sasser
Summary: This study analyzed herbaceous wetland vegetation species percent cover data collected over five growing seasons (2007-2011) to examine the unique species assemblages along the elevation gradient of deltaic islands in Wax Lake Delta. The research found two significant persistent species assemblages, with hurricanes and major river floods significantly affecting lower elevation plant species' aboveground cover.
Article
Green & Sustainable Science & Technology
Douglas A. A. Edmonds, Stephan C. C. Toby, Christopher G. G. Siverd, Robert Twilley, Samuel J. J. Bentley, Scott Hagen, Kehui Xu
Summary: Land loss in the Mississippi River Delta is caused by human activities that alter sediment budget, including dam building, levee construction, and subsurface resource extraction. A numerical model analysis reveals that the installation of flood-protection levees and the extraction of subsurface resources have been the primary drivers of land loss in the Barataria Basin within the delta. Additionally, the impact of dams on sediment supply reduction may not be as detrimental to sediment diversions and coastal restoration as previously thought.
NATURE SUSTAINABILITY
(2023)
Article
Ecology
Andre S. Rovai, Robert R. Twilley, Thomas A. Worthington, Pablo Riul
Summary: Mangroves in Brazil hold 8.5% of global mangrove carbon stocks and store up to 4.3 times more carbon in soil than other vegetated biomes. The organic carbon sequestration rates in Brazilian mangroves are 15-30% higher than global estimates. This research identifies Brazilian mangroves as a major global blue carbon hotspot and emphasizes their importance in carbon sequestration.
FRONTIERS IN FORESTS AND GLOBAL CHANGE
(2022)
Review
Ecology
Heida L. Diefenderfer, Gregory D. Steyer, Matthew C. Harwell, Andrew J. LoSchiavo, Hilary A. Neckles, David M. Burdick, Gary E. Johnson, Kate E. Buenau, Elene Trujillo, John C. Callaway, Ronald M. Thom, Neil K. Ganju, Robert R. Twilley
Summary: In large-scale ecosystem restoration efforts, the cumulative effects of interacting restoration projects have positive impacts on species and ecosystems at landscape and regional scales, and can help reduce countervailing effects.
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT
(2021)