Complex interactions of in-stream DOM and nutrient spiralling unravelled by Bayesian regression analysis

Abstract. Uptake and release patterns of dissolved organic matter (DOM) compounds and nutrients are entangled, and the current literature does not provide a consistent picture of the link between DOM composition, nutrient concentrations, and effects on their cycling. We performed two plateau addition experiments for each of five different, realistic, complex DOM leachates in a small stream, heavily enriched in nitrate but not phosphate or DOM due to diffuse agricultural pollution. By including cow and pig dung as well as corn, leaves and nettles leachates, the study used a wide range of different DOM qualities. We measured changes in nutrient concentrations and determined DOM fractions by fluorescence measurements and parallel factor (PARAFAC) decomposition. To assess influences from hydrological transport processes, we used a 1-D hydrodynamic model. We propose a non-linear Bayesian approach to the nutrient spiralling concept, the Interactions in Nutrient Spirals using BayesIan REgression (INSBIRE) approach. This approach can disentangle complex and interacting biotic and abiotic drivers in nutrient uptake metrics, show their variability and quantify their error distribution. Furthermore, previous knowledge on nutrient spiralling can be included in the model using prior probability distributions. We used INSBIRE to assess interactions of compound-specific DOM and nutrient spiralling metrics the data of our experiment. The uptake processes of different DOM fractions were linked to each other. We observed stimulating and dampening effects of DOM fractions on each other and the overall DOM uptake. We found saturation effects for dissolved organic carbon (concentration of C, DOC) uptake, as rising concentrations of a DOM fraction dampened its uptake. The degradation of a humic DOM component of terrestrial origin was stimulated by other DOM fractions, pointing to priming effects. We also found an influence of the wetted width on the uptake of soluble reactive phosphorus (SRP) and a microbially derived humic substance, which indicates the importance of the sediment-water interface for P and humic C cycling in the studied stream. Interestingly, we found no interactions between DOM uptake and nitrate or SRP concentrations, or any effect of the added DOM leachates on nitrate uptake, indicating that the increase in DOC concentrations and SRP concentrations were not sufficient to affect the relatively steady nitrate uptake during the experiments. Overall, we show that bulk DOC is a weak predictor of DOC uptake behaviour for complex DOM leachates and that individual DOM compound uptake, nitrate uptake and SRP uptake are controlled very differently within the same aquatic ecosystem. We also found effects of hydromorphology on the uptake of one humic fluorophore and SRP. We conclude that cycling of different C fractions, their interaction and interactions with N and P uptake in streams is a complex, non-linear problem, which can only be assessed with advanced non-linear approaches, such as we present with INSBIRE.

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Complex interactions of in-stream DOM and nutrient spiralling unravelled by Bayesian regression analysis

10.5194/egusphere-egu21-7804 ◽

2021 ◽

Author(s):

Matthias Pucher ◽

Peter Flödl ◽

Daniel Graeber ◽

Klaus Felsenstein ◽

Thomas Hein ◽

...

Keyword(s):

Nutrient Uptake ◽

Nutrient Dynamics ◽

Gas Production ◽

Transport Processes ◽

Bayesian Regression ◽

Nutrient Concentrations ◽

Cow Dung ◽

Small Stream ◽

Fluorescence Measurements ◽

Nutrient Spiralling

The carbon cycle in aquatic environments is of high interest because of its effects on water quality and greenhouse gas production as well as its alteration through anthropogenic activities with unknown outcomes. Uptake and release of dissolved organic matter (DOM) compounds is depending on the molecular structure and is strongly linked to N and P dynamics. Current research has not fully revealed the complex patterns behind.To investigate the interactions between DOM components, we performed ten plateau addition experiments with different, realistic, complex DOM leachates (cow dung, pig dung, corn, leaves and nettles) in a small stream. The DOM quality was determined by fluorescence measurements and parallel factor (PARAFAC) decomposition and the nutrient concentrations were measured at eleven consecutive points in the stream at plateau conditions. The hydrological transport processes were incorporated by using the results of a 1-D hydrodynamic model.The nutrient spiralling concept and its application in nutrient dynamics is a valuable basis for the analysis of our data. However, we could not find a data analysis approach, that suited the nature of our questions and data. Based on previously observed nutrient uptake models, we extended the nutrient spiralling concept by additional non-linear terms to analyse interactions between different DOM components.We developed the &#8220;Interactions in Nutrient Spirals using BayesIan REgression (INSBIRE)&#8221; approach to analyse DOM uptake and retention mechanism. This approach can disentangle complex and interacting biotic and abiotic drivers in nutrient uptake metrics, show their variability and quantify their error distribution. We successfully used INSBIRE to show DOM-compound-specific interactions and draw conclusions from the data of our experiment. The applicability of INSBIRE has still to be tested in other studies, but we see a high potential not only in DOM dynamics but any kind of solute dynamics where interactions are crucial.

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Complex interactions of in-stream dissolved organic matter and nutrient spiralling unravelled by Bayesian regression analysis

Biogeosciences ◽

10.5194/bg-18-3103-2021 ◽

2021 ◽

Vol 18 (10) ◽

pp. 3103-3122

Author(s):

Matthias Pucher ◽

Peter Flödl ◽

Daniel Graeber ◽

Klaus Felsenstein ◽

Thomas Hein ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Transport Processes ◽

Bayesian Regression ◽

Positive Interactions ◽

Cow Dung ◽

Complex Interactions ◽

Fluorescence Measurements ◽

Non Linear ◽

Nutrient Spiralling

Abstract. Uptake and release patterns of dissolved organic matter (DOM) compounds and co-transported nutrients are entangled, and the current literature does not provide a consistent picture of the interactions between the retention processes of DOM fractions. We performed plateau addition experiments with five different complex DOM leachates in a small experimental stream impacted by diffuse agricultural pollution. The study used a wide range of DOM qualities by including leachates of cow dung, pig dung, corn leaves, leaves from trees, and whole nettle plants. We measured changes in nutrient and dissolved organic carbon (DOC) concentrations along the stream course and determined DOM fractions by fluorescence measurements and parallel factor (PARAFAC) decomposition. To assess the influences of hydrological transport processes, we used a 1D hydrodynamic model. We developed a non-linear Bayesian approach based on the nutrient spiralling concept, which we named the “interactions in nutrient spirals using Bayesian regression” (INSBIRE) approach. This approach can disentangle complex interactions of biotic and abiotic drivers of reactive solutes' uptake in multi-component DOM sources. It can show the variability of the uptake velocities and quantify their uncertainty distributions. Furthermore, previous knowledge of nutrient spiralling can be included in the model using prior probability distributions. We used INSBIRE to assess interactions of compound-specific DOM and nutrient spiralling metrics in our experiment. Bulk DOC uptake varied among sources, showing decreasing uptake velocities in the following order: corn > pig dung > leaves > nettles > cow dung. We found no correlations between bulk DOC uptake and the amounts of protein-like compounds or co-leached soluble reactive phosphorus (SRP). The fastest uptake was observed for SRP and the tryptophan-like component, while the other DOM components' uptake velocities more or less resembled that of the bulk DOC. Almost all DOM components showed a negative relationship between uptake and concentration, known as efficiency loss. Furthermore, we observed a few negative and (weak) positive interactions between the uptake and the concentration of different components, such as a decreased uptake of protein-like compounds at high concentrations of a high-molecular-weight humic-like compound. We also found an influence of the wetted width on the uptake of SRP and a microbially derived humic substance, which indicates the importance of the sediment–water interface for P and humic C cycling in the studied stream. Overall, we show that bulk DOC is a weak predictor of DOC uptake behaviour for complex DOM leachates. Individual DOM compound uptake, including co-leached nutrients, is controlled by both internal (quality-related) and external (environmental) factors within the same aquatic ecosystem. We conclude that the cycling of different C fractions and their mutual interaction with N and P uptake in streams is a complex, non-linear problem, which can only be assessed with advanced non-linear approaches, such as the presented INSBIRE approach.

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Hydroclimatological Patterns and Limnological Characteristics of Unique Wetland Systems on the Argentine High Andean Plateau

Hydrology ◽

10.3390/hydrology8040164 ◽

2021 ◽

Vol 8 (4) ◽

pp. 164

Author(s):

Diego Frau ◽

Brendan J. Moran ◽

Felicity Arengo ◽

Patricia Marconi ◽

Yamila Battauz ◽

...

Keyword(s):

Soluble Reactive Phosphorus ◽

High Sensitivity ◽

High Elevation ◽

Climatic Conditions ◽

The Body ◽

Nutrient Concentrations ◽

Wide Range ◽

Human Perturbations ◽

Baseline Information ◽

The Impact

High-elevation wetlands in South America are not well described despite their high sensitivity to human impact and unique biodiversity. We describe the hydroclimatological and limnological characteristics of 21 wetlands on the High Andean Plateau of Argentina, synthesizing information gathered over ten years (2010–2020). We collected physical-chemical, phytoplankton, and zooplankton data and counted flamingos in each wetland. We also conducted an extensive analysis of climatic patterns and hydrological responses since 1985. These wetlands are shallow, with a wide range of salinity (from fresh to brine), mostly alkaline, and are dominated by carbonate and gypsum deposits and sodium-chloride waters. They tend to have high nutrient concentrations. Plankton shows a low species richness and moderate to high dominance of taxa. Flamingos are highly dependent on the presence of Bacillariophyta, which appears to be positively linked to silica and soluble reactive phosphorus availability. Climatic conditions show a strong region-wide increase in average air temperature since the mid-1980s and a decrease in precipitation between 1985–1999 and 2000–2020. These high-elevation wetlands are fundamentally sensitive systems; therefore, having baseline information becomes imperative to understanding the impact of climatic changes and other human perturbations. This work attempts to advance the body of scientific knowledge of these unique wetland systems.

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Nitrogen and Phosphorus Uptake Dynamics in Tropical Cerrado Woodland Streams

Water ◽

10.3390/w10081080 ◽

2018 ◽

Vol 10 (8) ◽

pp. 1080 ◽

Cited By ~ 2

Author(s):

Nícolas Reinaldo Finkler ◽

Flavia Tromboni ◽

Iola Boëchat ◽

Björn Gücker ◽

Davi Gasparini Fernandes Cunha

Keyword(s):

Nutrient Uptake ◽

N Uptake ◽

Pollution Abatement ◽

Phosphorus Uptake ◽

Soluble Reactive Phosphorus ◽

Nitrogen Retention ◽

Water Velocity ◽

Nutrient Concentrations ◽

Nitrogen And Phosphorus ◽

Lotic Ecosystem

Pollution abatement through phosphorus and nitrogen retention is a key ecosystem service provided by streams. Human activities have been changing in-stream nutrient concentrations, thereby altering lotic ecosystem functioning, especially in developing countries. We estimated nutrient uptake metrics (ambient uptake length, areal uptake rate, and uptake velocity) for nitrate (NO3–N), ammonium (NH4–N), and soluble reactive phosphorus (SRP) in four tropical Cerrado headwater streams during 2017, through whole-stream nutrient addition experiments. According to multiple regression models, ambient SRP concentration was an important explanatory variable of nutrient uptake. Further, best models included ambient NO3–N and water velocity (for NO3–N uptake metrics), dissolved oxygen (DO) and canopy cover (for NH4–N); and DO, discharge, water velocity, and temperature (for SRP). The best kinetic models describing nutrient uptake were efficiency-loss (R2 from 0.47–0.88) and first-order models (R2 from 0.60–0.85). NO3–N, NH4–N, and SRP uptake in these streams seemed coupled as a result of complex interactions of biotic P limitation, abiotic P cycling processes, and the preferential uptake of NH4–N among N-forms. Global change effects on these tropical streams, such as temperature increase and nutrient enrichment due to urban and agricultural expansion, may have adverse and partially unpredictable impacts on whole-stream nutrient processing.

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On differential operators and unifying relations for 1-loop Feynman integrands

Journal of High Energy Physics ◽

10.1007/jhep10(2021)150 ◽

2021 ◽

Vol 2021 (10) ◽

Author(s):

Kang Zhou

Keyword(s):

Sigma Model ◽

Differential Operators ◽

Linear Sigma Model ◽

Tree Level ◽

Maxwell Theory ◽

Scalar Theory ◽

Yang Mills ◽

Loop Level ◽

Wide Range ◽

Non Linear

Abstract We generalize the unifying relations for tree amplitudes to the 1-loop Feynman integrands. By employing the 1-loop CHY formula, we construct differential operators which transmute the 1-loop gravitational Feynman integrand to Feynman integrands for a wide range of theories, including Einstein-Yang-Mills theory, Einstein-Maxwell theory, pure Yang-Mills theory, Yang-Mills-scalar theory, Born-Infeld theory, Dirac-Born-Infeld theory, bi-adjoint scalar theory, non-linear sigma model, as well as special Galileon theory. The unified web at 1-loop level is established. Under the well known unitarity cut, the 1-loop level operators will factorize into two tree level operators. Such factorization is also discussed.

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Deformation of rockfill in bodies of rockfill dams

Stroitel stvo nauka i obrazovanie [Construction Science and Education] ◽

10.22227/2305-5502.2019.3.5 ◽

2019 ◽

pp. 5-5

Author(s):

Mikhail Sainov

Keyword(s):

Reinforced Concrete ◽

Deformation Modulus ◽

Deformation Model ◽

Observation Data ◽

Linear Deformation ◽

Laboratory Test Results ◽

Wide Range ◽

Deformation Properties ◽

Non Linear ◽

The Impact

Introduction. The main factor determining the stress-strain state (SSS) of rockfill dam with reinforced concrete faces is deformability of the dam body material, mostly rockfill. However, the deformation properties of rockfill have not been sufficiently studied yet for the time being due to technical complexity of the matter, Materials and methods. To determine the deformation parameters of rockfill, scientific and technical information on the results of rockfill laboratory tests in stabilometers were collected and analyzed, as well as field data on deformations in the existing rockfill dams. After that, the values of rockfill linear deformation modulus obtained in the laboratory and in the field were compared. The laboratory test results were processed and analyzed to determine the parameters of the non-linear rockfill deformation model. Results. Analyses of the field observation data demonstrates that the deformation of the rockfill in the existing dams varies in a wide range: its linear deformation modulus may vary from 30 to 500 МPа. It was found out that the results of the most rockfill tests conducted in the laboratory, as a rule, approximately correspond to the lower limit of the rockfill deformation modulus variation range in the bodies of the existing dams. This can be explained by the discrepancy in density and particle sizes of model and natural soils. Only recently, results of rockfill experimental tests were obtained which were comparable with the results of the field measurements. They demonstrate that depending on the stress state the rockfill linear deformation modulus may reach 700 МPа. The processing of the results of those experiments made it possible to determine the parameters on the non-linear model describing the deformation of rockfill in the dam body. Conclusions. The obtained data allows for enhancement of the validity of rockfill dams SSS analyses, as well as for studying of the impact of the non-linear character of the rockfill deformation on the SSS of reinforced concrete faces of rockfill dams.

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Physical Transport Processes that Affect the Distribution of Oil in the Gulf of Mexico: Observations and Modeling

Oceanography ◽

10.5670/oceanog.2021.117 ◽

2021 ◽

Vol 34 (1) ◽

pp. 58-75

Author(s):

Michel Boufadel ◽

◽

Annalisa Bracco ◽

Eric Chassignet ◽

Shuyi Chen ◽

...

Keyword(s):

Gulf Of Mexico ◽

Physical Environment ◽

Large Scale ◽

Transport Processes ◽

Small Scale ◽

Surface Mixed Layer ◽

Physical Processes ◽

Mixing Processes ◽

Near Surface ◽

Wide Range

Physical transport processes such as the circulation and mixing of waters largely determine the spatial distribution of materials in the ocean. They also establish the physical environment within which biogeochemical and other processes transform materials, including naturally occurring nutrients and human-made contaminants that may sustain or harm the region’s living resources. Thus, understanding and modeling the transport and distribution of materials provides a crucial substrate for determining the effects of biological, geological, and chemical processes. The wide range of scales in which these physical processes operate includes microscale droplets and bubbles; small-scale turbulence in buoyant plumes and the near-surface “mixed” layer; submesoscale fronts, convergent and divergent flows, and small eddies; larger mesoscale quasi-geostrophic eddies; and the overall large-scale circulation of the Gulf of Mexico and its interaction with the Atlantic Ocean and the Caribbean Sea; along with air-sea interaction on longer timescales. The circulation and mixing processes that operate near the Gulf of Mexico coasts, where most human activities occur, are strongly affected by wind- and river-induced currents and are further modified by the area’s complex topography. Gulf of Mexico physical processes are also characterized by strong linkages between coastal/shelf and deeper offshore waters that determine connectivity to the basin’s interior. This physical connectivity influences the transport of materials among different coastal areas within the Gulf of Mexico and can extend to adjacent basins. Major advances enabled by the Gulf of Mexico Research Initiative in the observation, understanding, and modeling of all of these aspects of the Gulf’s physical environment are summarized in this article, and key priorities for future work are also identified.

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Non-Linear Dynamic Magneto Electric Effects in Ferromagnetic-Ferroelectric Layered Composites

Volume 9: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2013-66451 ◽

2013 ◽

Author(s):

Satenik Harutyunyan ◽

Davresh Hasanyan

Keyword(s):

Vibration Frequency ◽

Strain Distribution ◽

Longitudinal Vibration ◽

Three Dimensional ◽

Low Frequency ◽

Structure Design ◽

Experimental Results ◽

Physical Parameters ◽

Wide Range ◽

Non Linear

A non-linear theoretical model including bending and longitudinal vibration effects was developed for predicting the magneto electric (ME) effects in a laminate bar composite structure consisting of magnetostrictive and piezoelectric multi-layers. If the magnitude of the applied field increases, the deflection rapidly increases and the difference between experimental results and linear predictions becomes large. However, the nonlinear predictions based on the present model well agree with the experimental results within a wide range of applied electric field. The results of the analysis are believed to be useful for materials selection and actuator structure design of actuator in actuator fabrication. It is shown that the problem for bars of symmetrical structure is not divided into a plane problem and a bending problem. A way of simplifying the solution of the problem is found by an asymptotic method. After solving the problem for a laminated bar, formula that enable one to change from one-dimensional required quantities to three dimensional quantities are obtained. The derived analytical expression for ME coefficients depend on vibration frequency and other geometrical and physical parameters of laminated composites. Parametric studies are presented to evaluate the influences of material properties and geometries on strain distribution and the ME coefficient. Analytical expressions indicate that the vibration frequency strongly influences the strain distribution in the laminates, and that these effects strongly influence the ME coefficients. It is shown that for certain values of vibration frequency (resonance frequency), the ME coefficient becomes infinity; as a particular case, low frequency ME coefficient were derived as well.

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Rotorcraft control response using linearised and non-linear flight dynamic models with different inflow models

The Aeronautical Journal ◽

10.1017/aer.2017.8 ◽

2017 ◽

Vol 121 (1238) ◽

pp. 553-575 ◽

Cited By ~ 1

Author(s):

T. Sakthivel ◽

C. Venkatesan

Keyword(s):

Dynamic Model ◽

Dynamic Models ◽

Model Identification ◽

Flight Test ◽

Step Size ◽

Response Characteristics ◽

Wide Range ◽

Non Linear ◽

Steady Level ◽

Control Response

ABSTRACTThe aim of the present study is to develop a relatively simple flight dynamic model which should have the ability to analyse trim, stability and response characteristics of a rotorcraft under various manoeuvring conditions. This study further addresses the influence of numerical aspects of perturbation step size in linearised model identification and integration timestep on non-linear model response. In addition, the effects of inflow models on the non-linear response are analysed. A new updated Drees inflow model is proposed in this study and the applicability of this model in rotorcraft flight dynamics is studied. It is noted that the updated Drees inflow model predicts the control response characteristics fairly close to control response characteristics obtained using dynamic inflow for a wide range of flight conditions such as hover, forward flight and recovery from steady level turn. A comparison is shown between flight test data, the control response obtained from the simple flight dynamic model, and the response obtained using a more detailed aeroelastic and flight dynamic model.

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Plasma Diagnostics of Microflares observed by STIX and AIA

10.5194/egusphere-egu21-7966 ◽

2021 ◽

Author(s):

Jonas Saqri ◽

Astrid Veronig ◽

Ewan Dickson ◽

Säm Krucker ◽

Andrea Francesco Battaglia ◽

...

Keyword(s):

Solar Flares ◽

Magnetic Energy ◽

Emission Measure ◽

Transport Processes ◽

X Rays ◽

Solar Dynamics Observatory ◽

Energy Bands ◽

Accurate Analysis ◽

Great Opportunity ◽

Wide Range

Solar flares are generally thought to be the impulsive release of magnetic energy giving rise to a wide range of solar phenomena that influence the heliosphere and in some cases even conditions of earth. Part of this liberated energy is used for particle acceleration and to heat up the solar plasma. The Spectrometer/Telescope for Imaging X-rays (STIX) instrument onboard the Solar Orbiter mission launched on February 10th 2020 promises advances in the study of solar flares of various sizes. It is capable of measuring X-ray spectra from 4 to 150 keV with 1 keV resolution binned into 32 energy bins before downlinking. With this energy range and sensitivity, STIX is capable of sampling thermal plasma with temperatures of&#8819;10 MK, and to diagnose the nonthermal bremsstrahlung emission of flare-accelerated electrons. During the spacecraft commissioning phase in the first half of the year 2020, STIX observed 68 microflares. Of this set, 26 events could clearly be identified in at least two energy channels, all of which originated in an active region that was also visible from earth. These events provided a great opportunity to combine the STIX observations with the multi-band EUV imagery from the Atmospheric Imaging Assembly (AIA) instrument on board the earth orbiting Solar Dynamics Observatory (SDO). For the microflares that could be identified in two STIX science energy bands, it was possible to derive the temperature and emission measure (EM) of the flaring plasma assuming an isothermal source. For larger events where more detailed spectra could be derived, a more accurate analysis was performed by fitting the spectra assuming various thermal and nonthermal sources. These results are compared to the diagnostics derived from AIA images. To this aim, the Differential EmissionMeasure (DEM) was reconstructed from AIA observations to infer plasma temperatures and EM in the flaring regions. Combined with the the relative timing between the emission seen by STIX and AIA, this allows us to get deeper insight into the flare energy release and transport processes.

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