Article
Environmental Sciences
Ruzhong Li, Yang Fu, Daqiang Xu, Xiaohui Wang, Guangqiu Jin
Summary: This study conducted experiments in two mesotrophic agricultural headwater streams to analyze the interactions between NH4-N and PO4-P uptake, showing that dual-nutrient additions increased their uptake capacity. Water temperature may be the main factor influencing the coupling of N and P uptake in mesotrophic streams.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2021)
Article
Limnology
Christine Anlanger, Ute Risse-Buhl, Daniel von Schiller, Christian Noss, Markus Weitere, Andreas Lorke
Summary: Epibenthic biofilms play a crucial role in regulating nitrogen fluxes in stream ecosystems. The efficiency of this regulation is influenced by both hydraulic and biological processes, with high within-stream variability observed in biofilm N uptake and uptake velocity. These findings enhance our understanding of the processes involved in biofilm N uptake at small scales and support upscaling to larger spatiotemporal scales along stream networks.
LIMNOLOGY AND OCEANOGRAPHY
(2021)
Article
Environmental Sciences
Xiaolin Zhang, Xiaoqiang Yang, Robert Hensley, Andreas Lorke, Michael Rode
Summary: In-stream nitrate uptake in rivers is influenced by complex autotrophic and heterotrophic pathways, which vary spatiotemporally. High-frequency monitoring of nitrate mass balance can quantitatively analyze uptake dynamics, but has not been fully explored in higher-order streams. We conducted monitoring in five high-order stream reaches, finding substantial differences in net nitrate uptake rates and the dominance of different processes between wet and dry seasons. These findings advance our understanding of N-retention processes at the reach scale and can contribute to river-network modeling concepts.
WATER RESOURCES RESEARCH
(2023)
Article
Environmental Sciences
Jose Schreckinger, Michael Mutz, Clara Mendoza-Lera
Summary: Climate change and human water demand have caused more frequent and longer drying periods in rivers and streams globally. The biogeochemical processes during the water return in these dried riverbeds are not well understood. This study found that the attributes of drying, including duration and intensity, have significant impacts on the biogeochemical dynamics upon flow resumption. However, within four days, respiration and nutrient dynamics did not recover to pre-drying levels.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Environmental Sciences
Christa L. Torrens, Michael N. Gooseff, Diane M. McKnight
Summary: This study examines the relationship between DOC and stream discharge in the glacial meltwater streams of the McMurdo Dry Valleys in Antarctica. The findings suggest that the autochthonous organic matter pools have sufficient DOC generation rates to maintain chemostasis in these streams. A conceptual model is proposed to explain the key components that enable chemostatic DOC-q behavior in these streams.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2022)
Article
Environmental Sciences
D. W. Clow, G. A. Akie, R. G. Striegl, C. A. Penn, G. A. Sexstone, G. L. Keith
Summary: This study measured aquatic carbon fluxes in mountain headwater streams and used a geostatistical analysis to determine how landscape characteristics influence these fluxes. The findings showed that wetlands have a positive influence on aquatic carbon fluxes, while perennial snow/ice has a negative effect. Mean annual temperature and precipitation also have impacts on aquatic carbon fluxes. Furthermore, dissolved organic matter and bicarbonate ions in the water showed strong dynamic responses to snowmelt and rain events.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Meteorology & Atmospheric Sciences
C. M. Siegert, Z. J. Suriano, D. J. Leathers, A. J. Gold, K. Addy, A. W. Schroth, E. Seybold, S. Inamdar, D. F. Levia
Summary: Synoptic typing is a useful method for classifying atmospheric conditions and their impacts on terrestrial processes, as shown in this study on stream dynamics in forested watersheds. Regional synoptic weather analyses provide valuable insights into variations in carbon and nitrate stream export. Regardless of watershed size or location, similar water and solute fluxes were classified using synoptic typing, with storms from more frequent synoptic types dominating the fluxes.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2021)
Article
Environmental Sciences
Dominic Vachon, Ryan A. Sponseller, Martin Rosvall, Jan Karlsson
Summary: Inland waters are important in the carbon cycle by releasing carbon from the land into the atmosphere. The regulation of integrated fluxes of organic and inorganic carbon in connected networks of streams and lakes is poorly understood.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Oceanography
Kenneth S. Johnson, Matthew R. Mazloff, Mariana B. Bif, Yuichiro Takeshita, Hans W. Jannasch, Tanya L. Maurer, Joshua N. Plant, Ariane Verdy, Peter M. Walz, Stephen C. Riser, Lynne D. Talley
Summary: Measurements of pH and nitrate were used to study the ratios of dissolved inorganic carbon (DIC) and nitrate (NO3) uptake in the Southern Ocean during the spring to summer bloom period. The effects of atmospheric CO2 exchange and mixing were separated from phytoplankton uptake using the B-SOSE model. The corrected, in situ biological uptake ratio (C:N) was found to be similar to the Redfield Ratio (RR), with a few exceptions.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Environmental Sciences
Charles Marty, Louis Duchesne, Suzanne Couture, Christian Gagnon, Daniel Houle
Summary: Reduction in SO42- and NO3- atmospheric deposition in the past decades has improved surface water quality in several catchments, but an increasing influence of climate and dissolved organic carbon (DOC) has been observed. Decreased acidic deposition resulted in a general recovery of surface water, although the parallel increase in DOC concentration prevented from an increase in water alkalinity. The study also indicates an increasing influence of climate on water chemistry at the study site, probably mediated by increasing weathering rate and vegetation nutrient uptake.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Environmental Sciences
Ji-Fa Cui, Shi-Jie Han, Xi-Mei Zhang, Xing-Guo Han, Zhi-Ping Wang
Summary: This study investigated the dissolved organic and inorganic carbon in artificially modified tributary streams in a farming region of the lower Yangtze River basin. The results showed significant temporal-spatial variability in the concentrations of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC). The concentrations of DOC and DIC exhibited a linear decreasing trend from source to export, with DOC concentration always lower than DIC concentration. The study also found a positive correlation between DOC and DIC concentration in one of the streams, suggesting potential similar sources for both carbon forms.
Article
Forestry
Lars Lundin, Torbjorn Nilsson
Summary: Forest fertilization with nitrogen can have adverse effects such as acidification and nitrate leaching. The study found high excess outflow of nitrogen, calcium, and magnesium, with nitrate dominating total nitrogen. Effects on pH were limited.
FOREST ECOLOGY AND MANAGEMENT
(2021)
Article
Engineering, Civil
G. Medici, P. Bajak, L. J. West, P. J. Chapman, S. A. Banwart
Summary: This study focuses on quantifying fluxes of DOC and nitrate in farmland, using the Transect Method to calculate mass fluxes in groundwater. The research found that localized contamination significantly impacts groundwater chemical concentrations and identified the vulnerable contamination zone. Future modeling efforts should target this shallow vulnerability zone and the Transect Method can be used to define boundary conditions.
JOURNAL OF HYDROLOGY
(2021)
Article
Engineering, Environmental
Jiefeng Wu, Huaxia Yao, Xing Yuan, Bingqing Lin
Summary: This study investigates the response relationship between dissolved organic carbon (DOC) and hydrological drought characteristics. It proposes an integrated framework to construct, validate, and apply a response model for simulating DOC based on hydrological drought. The results show a linear relationship between DOC and drought characteristics, and the response model performs well in simulating DOC during drought. These findings enhance our understanding of the relationship between DOC and drought.
Article
Astronomy & Astrophysics
Ariel Arza, Abaz Kryemadhi, Konstantin Zioutas
Summary: The axion dark matter echo technique is a method that aims to search for dark matter by detecting the electromagnetic echo from stimulated decay of ambient dark matter. This study considers deviations from the standard halo model in the form of fine grained streams and shows that the echo method is very sensitive to particular local axion dark matter distributions. The extremely small dispersion of the streams improves the sensitivity of the echo method in the axion-photon coupling up to two orders of magnitude.
Article
Environmental Sciences
Gopal K. Mulukutla, Wilfred M. Wollheim, Joseph E. Salisbury, Richard O. Carey, Thomas K. Gregory, William H. McDowell
Summary: Rapid changes in land use, pollution inputs, and climate are altering the quantity, timing, and form of materials delivered from watersheds to estuaries. The study found that the watershed strongly controls the concentrations of terrestrially derived DOC in the estuary, while estuarine nitrate patterns are more complex due to heterogeneous watershed distribution of non-point and point sources and high reactivity of nitrate in the estuary. Understanding estuarine biogeochemical patterns will be advanced through greater use of simultaneous sub-hourly measurements of inflows, salinity, and water quality in estuaries and their upstream watersheds.
ESTUARIES AND COASTS
(2022)
Article
Environmental Sciences
William H. McDowell
Summary: Dissolved organic matter (DOM) is a heterogeneous mixture of organic compounds that is produced through microbial degradation and abiotic leaching, and it plays an important role in aquatic ecology and watershed management. The challenges in studying DOM include monitoring long-term changes, using sensors for short-term dynamics, understanding its role in the carbon cycle and greenhouse gas evasion, and exploring its evolutionary significance in various environments.
Article
Multidisciplinary Sciences
Christopher J. Patrick, John S. Kominoski, William H. McDowell, Benjamin Branoff, David Lagomasino, Miguel Leon, Enie Hensel, Marc J. S. Hensel, Bradley A. Strickland, T. Mitchell Aide, Anna Armitage, Marconi Campos-Cerqueira, Victoria M. Congdon, Todd A. Crowl, Donna J. Devlin, Sarah Douglas, Brad E. Erisman, Rusty A. Feagin, Simon J. Geist, Nathan S. Hall, Amber K. Hardison, Michael R. Heithaus, J. Aaron Hogan, J. Derek Hogan, Sean Kinard, Jeremy J. Kiszka, Teng-Chiu Lin, Kaijun Lu, Christopher J. Madden, Paul A. Montagna, Christine S. O'Connell, C. Edward Proffitt, Brandi Kiel Reese, Joseph W. Reustle, Kelly L. Robinson, Scott A. Rush, Rolando O. Santos, Astrid Schnetzer, Delbert L. Smee, Rachel S. Smith, Gregory Starr, Beth A. Stauffer, Lily M. Walker, Carolyn A. Weaver, Michael S. Wetz, Elizabeth R. Whitman, Sara S. Wilson, Jianhong Xue, Xiaoming Zou
Summary: This study analyzed ecosystem time series data in the Northern Hemisphere to understand the patterns of resistance and resilience in coastal ecosystems subjected to tropical cyclones. The results suggest that there is a trade-off between resistance and resilience, which may be a result of evolutionary adaptation. These findings are important for predicting the impact of climate change on coastal ecosystems.
Article
Geosciences, Multidisciplinary
S. A. Hynek, W. H. McDowell, M. P. Bhatt, J. J. Orlando, S. L. Brantley
Summary: This study explores the impact of different types of rocks and fracture patterns on stream chemistry and regolith development. The results demonstrate the significant role of lithology and fracture patterns in dictating water flowpaths, stream chemistry, and regolith development in headwater catchments.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Environmental Sciences
P. H. Templer, J. L. Harrison, F. Pilotto, A. Flores-Diaz, P. Haase, W. H. McDowell, R. Sharif, H. Shibata, D. Blankman, A. Avila, U. Baatar, H. R. Bogena, I Bourgeois, J. Campbell, T. Dirnboeck, W. K. Dodds, M. Hauken, I Kokorite, K. Lajtha, I-L Lai, H. Laudon, T. C. Lin, S. R. M. Lins, H. Meesenburg, P. Pinho, A. Robison, M. Rogora, B. Scheler, P. Schleppi, R. Sommaruga, T. Staszewski, M. Taka
Summary: This study synthesized data from sites around the globe to evaluate the effects of atmospheric nitrogen inputs and climate on stream nitrogen concentrations and fluxes. The findings indicate that atmospheric nitrogen inputs and precipitation remain important predictors for inorganic nitrogen exported from forested and grassland watersheds, despite declining nitrogen deposition over time.
Article
Geosciences, Multidisciplinary
Junfeng Wang, Xinghui Xia, Shaoda Liu, Sibo Zhang, Ling Zhang, Chenrun Jiang, Zhenrui Zhang, Yuan Xin, Xin Chen, Jing Huang, Jiaao Bao, William H. McDowell, Greg Michalski, Zhifeng Yang, Jun Xia
Summary: This study finds that the water column plays an important role in nitrogen cycling processes in rivers, which is often neglected. Observations across six river networks in China show that the water-air and sediment-water fluxes of N-2 and N2O decrease, while the water column production increases with stream order. The water column contribution increases with stream order and accounts for more than 50% in rivers above fifth order. Neglecting water column processes would lead to an underestimation of N removal and N2O emissions by approximately 50% for these river networks.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Ecology
William H. McDowell, Jody D. Potter
Summary: Soil solution chemistry is sensitive to disturbance but resilient, with a return to baseline after 12-18 months. Canopy loss and detrital inputs result in increased nitrate concentrations, while potassium increases following drought and hurricanes. Phosphorus only increases following hurricanes in plots that received previous manipulation.
Article
Environmental Sciences
Desneiges S. Murray, Michelle D. Shattuck, William H. McDowell, Adam S. Wymore
Summary: It was found that wet deposition of inorganic nitrogen is declining while organic nitrogen is increasing, and precipitation type has a significant impact on nitrogen stoichiometry. With climate change and shifting seasonality, future precipitation is predicted to bring more reduced nitrogen-enriched rainwater into the biosphere.
Editorial Material
Ecology
Christopher J. Patrick, Enie Hensel, John S. Kominoski, Beth A. Stauffer, William H. McDowell
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT
(2022)
Article
Environmental Sciences
Allison M. Herreid, Carla Lopez Lloreda, Adam S. Wymore, Jody D. Potter, William H. McDowell
Summary: This study uses data from eight tropical watersheds in Puerto Rico to show that rivers in these watersheds are sources of greenhouse gases (GHGs) to the atmosphere. The concentrations of carbon dioxide (CO2) and nitrous oxide (N2O) are influenced by surrounding inputs, while the concentration of methane (CH4) is related to in-stream oxygen availability and lithology.
Article
Limnology
Michelle D. Shattuck, Hannah M. Fazekas, Adam S. Wymore, Aneliya Cox, William H. McDowell
Summary: Elevated salt concentrations are common in streams draining developed watersheds, but the role of hydrologic variability and groundwater in surface water salinization is not well understood. This study used long-term and high-frequency specific conductance data to analyze 13 streams in New Hampshire, USA. The results showed seasonal variation in chloride concentrations, with both dilution and flushing behavior occurring, indicating contributions from groundwater and surface runoff. Extreme flood events initially reduced salt concentrations, but concentrations recovered in about a decade. Chronic chloride exceedances were observed in urban streams throughout the year. This research highlights the importance of stream flow variation, extreme events, and deicing agents in freshwater salinization.
LIMNOLOGY AND OCEANOGRAPHY LETTERS
(2023)
Article
Multidisciplinary Sciences
Jakub Hruska, Filip Oulehle, Tomas Chuman, Tomas Kolar, Michal Rybnicek, Miroslav Trnka, William H. McDowell
Summary: In the past 40 years, the forests of central Europe have undergone significant transitions due to improved air quality. Air pollution, particularly high concentrations of SO2 and acidic deposition, plays a crucial role in driving forest health. Extensive soil acidification occurred in the highly polluted Black Triangle region, but there has been a decline in atmospheric acid deposition and SO2 concentrations. The recovery of tree ring width is closely linked to the trajectory of SO2 concentrations or sulfur deposition.
Article
Environmental Sciences
Adam S. Wymore, William Larsen, Dustin W. Kincaid, Kristen L. Underwood, Hannah M. Fazekas, William H. McDowell, Desneiges S. Murray, Arial J. Shogren, Shannon L. Speir, Alex J. Webster
Summary: Concentration-discharge (C-Q) relationships are commonly used to understand material export from watersheds. While the power-law function has been widely applied, it has not been rigorously tested and evaluated in over 50 years. In this study, we reexamined the original models and found that the power-law analysis remains one of the best performing models, though other models also performed well.
WATER RESOURCES RESEARCH
(2023)
Article
Environmental Sciences
Bianca M. Rodriguez-Cardona, Daniel Houle, Suzanne Couture, Jean-Francois Lapierre, Paul A. del Giorgio
Summary: The browning of northern lakes is associated with increases in dissolved organic carbon and color, as well as changes in surface water carbon dioxide. The long-term covariation between these three key carbon components of lake functioning has yet to be assessed. Studies show that dissolved organic carbon and color generally increase in lakes, but the trends can vary greatly and may not be closely linked to carbon dioxide changes. Lakes with the greatest increase in dissolved organic carbon also tend to have the highest rates of change in color and carbon dioxide. The water retention time of lakes and watershed connectivity play important roles in determining the changes and coupling of these carbon components.
COMMUNICATIONS EARTH & ENVIRONMENT
(2023)
Article
Environmental Sciences
Desneiges S. Murray, Edom Moges, Laurel Larsen, Michelle D. Shattuck, William H. Mcdowell, Adam S. Wymore
Summary: This study investigates the impact of nitrogen wet deposition on watershed biogeochemical cycling using the transfer entropy method. The results show that wet deposition N has a lagged nonlinear effect on river N, with river DON being mostly influenced by wet deposition N. Additionally, the processes of mineralization and assimilation display stronger synchrony than nitrification.
WATER RESOURCES RESEARCH
(2023)
