Water Compartments Research Articles

GAMER-MRI in Multiple Sclerosis Identifies the Diffusion-Based Microstructural Measures That Are Most Sensitive to Focal Damage: A Deep-Learning-Based Analysis and Clinico-Biological Validation.

Conventional magnetic resonance imaging (cMRI) in multiple sclerosis (MS) patients provides measures of focal brain damage and activity, which are fundamental for disease diagnosis, prognosis, and the evaluation of response to therapy. However, cMRI is insensitive to the damage to the microenvironment of the brain tissue and the heterogeneity of MS lesions. In contrast, the damaged tissue can be characterized by mathematical models on multishell diffusion imaging data, which measure different compartmental water diffusion. In this work, we obtained 12 diffusion measures from eight diffusion models, and we applied a deep-learning attention-based convolutional neural network (CNN) (GAMER-MRI) to select the most discriminating measures in the classification of MS lesions and the perilesional tissue by attention weights. Furthermore, we provided clinical and biological validation of the chosen metrics—and of their most discriminative combinations—by correlating their respective mean values in MS patients with the corresponding Expanded Disability Status Scale (EDSS) and the serum level of neurofilament light chain (sNfL), which are measures of disability and neuroaxonal damage. Our results show that the neurite density index from neurite orientation and dispersion density imaging (NODDI), the measures of the intra-axonal and isotropic compartments from microstructural Bayesian approach, and the measure of the intra-axonal compartment from the spherical mean technique NODDI were the most discriminating (respective attention weights were 0.12, 0.12, 0.15, and 0.13). In addition, the combination of the neurite density index from NODDI and the measures for the intra-axonal and isotropic compartments from the microstructural Bayesian approach exhibited a stronger correlation with EDSS and sNfL than the individual measures. This work demonstrates that the proposed method might be useful to select the microstructural measures that are most discriminative of focal tissue damage and that may also be combined to a unique contrast to achieve stronger correlations to clinical disability and neuroaxonal damage.

Towards detection of inflammation in adipose tissue: Microscopic field simulations to estimate water signal properties

Inflammation of adipose tissue, particularly visceral adipose tissue, is assumed to be a causal factor for the development of type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular diseases. Invasive biopsy is currently mandatory for assessment and grading of adipose tissue inflammation. Magnetic resonance detection of the increased water content of inflamed adipose tissue is considered to be a non-invasive alternative. Additional water is mainly originating from macrophages clustering in small regions between adipocytes. This article addresses the characteristics of water signals from areas between adipocytes in terms of line width, line shape, and relaxation properties. Since water and lipids inside adipose tissue have different magnetic susceptibilities, microscopic field inhomogeneities arise depending on the geometry and orientation of the water containing confinements. Relatively pronounced microscopic field inhomogeneities in the water compartments cause a broad spectral distribution of water signals. As a consequence the water signal of adipose tissue shows special characteristics different to common parenchyma tissues, in which cell content and intercellular space consist of water. The broad and non-Lorentzian field distribution of signals emanating from the water compartments in adipose tissue results in a fast non-exponential signal decay. Therefore, short echo times are recommended for sensitive gradient-echo based imaging. A non-exponential irregular signal decay potentially leads to problems in fat/water separation using Dixon techniques. Marked microscopic field inhomogeneities in combination with diffusion related displacement of water molecules cause irreversible dephasing and therefore accelerated signal decay even for spin-echo sequences. A volume localized spectrum of porcine fat recorded at 3T by a STEAM sequence with an echo time of 5.4ms shows a broad water signal with a line width of 70Hz±4Hz, in contrast to the CH2-peak of lipids in the same spectrum with a line width of only 14.7Hz±0.7Hz. This finding is qualitatively consistent with the results of finite element modelling of the magnetic field in geometric models and experiments in phantoms with oil-filled balloons surrounded by water.

The role of ozone combined with UVC/H2O2 process for the tertiary treatment of a real slaughterhouse wastewater

The main goal of this work is to evaluate the usage of ozone (O3) as a pre-treatment or simultaneously combined with UVC/H2O2 process for the polishing stage treatment of real bio-treated slaughterhouse wastewater. Two different treatment strategies were tested: i) pre-ozonation of the wastewater followed by an UVC/H2O2 process (two-step treatment); ii) simultaneous application of O3/UVC/H2O2 combined process (one-step treatment). For the two-step strategy, the pre-treatment with 30 mg O3/min for 10 min reduces significantly total suspended solids (TSS), turbidity and colour, reducing light filtering effects and increasing the efficiency of the following UVC/H2O2 process. In turn, the one-step treatment strategy (O3/UVC/H2O2) allows a more efficient use of injected O3 by reducing the amount of O3 required (from 273 to 189 mg O3/Leffluent) to achieve similar mineralization levels. The real bio-treated slaughterhouse wastewater treated by O3/UVC/H2O2 process achieved final colour values of 20 Pt/Co, TSS of 35 mg/L and COD of 61 mg O2/L, allowing its direct discharge into water compartments according to European Council Directive 91/271/EEC.

The interplay of nutrients, dissolved inorganic carbon and algae in determining macrophyte occurrences in rivers

Nitrogen and phosphorous concentrations are widely considered to drive macrophyte assemblages in rivers. However, Dissolved Inorganic Carbon (DIC) – available for plants as CO2 and HCO3− – is also of major relevance. Based on literature, we present a conceptual model on the interaction between algae, macrophytes, DIC, pH, light, N, P and the surface water and sedimental compartment. Analysing two separate datasets (i) on river physico-chemistry and chlorophyll-a, and (ii) on river physico-chemistry and macrophytes we quantify three connections within this concept: (1) the correlation of chlorophyll-a versus pH, (2) the correlation of TP versus chlorophyll-a and (3) the occurrence of HCO3-users and CO2-only-users among macrophytes along the DIC gradient. Chlorophyll-a correlated positively with pH (R-squared = 77%, p < .001) due to increased carbon dioxide uptake of phytoplankton. Surface water TP did not linearly correlate with chlorophyll-a concentrations. Obligate and optionally submerged macrophyte species that utilise HCO3− were separated from CO2-only-users by HCO3− concentrations, with an area under the curve (AUC) of 68% and 70% (both p < .001) between groups. Obligate and optionally submerged macrophyte assemblages only composed of HCO3-users and those exclusively composed of CO2-only-users showed an even stronger separation based on the HCO3− concentration, with both an AUC of 82% and 78% (both p < .001). Our results underline that DIC can greatly affect riverine macrophytes. However, absolute concentrations of HCO3− are less relevant, while the connection to pH is more important, reflecting CO2 concentrations. River monitoring and management should consider the interaction between nutrients DIC, surface water and sedimental compartment as important factors affecting macrophyte occurrence, rather than solely focussing on surface water nutrients.

Standard MRI-based attenuation correction for PET/MRI phantoms: a novel concept using MRI-visible polymer

BackgroundPET/MRI phantom studies are challenged by the need of phantom-specific attenuation templates to account for attenuation properties of the phantom material. We present a PET/MRI phantom built from MRI-visible material for which attenuation correction (AC) can be performed using the standard MRI-based AC.MethodsA water-fillable phantom was 3D-printed with a commercially available MRI-visible polymer. The phantom had a cylindrical shape and the fillable compartment consisted of a homogeneous region and a region containing solid rods of different diameters. The phantom was filled with a solution of water and [18F]FDG. A 30 min PET/MRI acquisition including the standard Dixon-based MR-AC method was performed. In addition, a CT scan of the phantom was acquired on a PET/CT system.From the Dixon in-phase, opposed-phase and fat images, a phantom-specific AC map (Phantom MR-AC) was produced by separating the phantom material from the water compartment using a thresholding-based method and assigning fixed attenuation coefficients to the individual compartments. The PET data was reconstructed using the Phantom MR-AC, the original Dixon MR-AC, and an MR-AC just containing the water compartment (NoWall-AC) to estimate the error of ignoring the phantom walls. CT-based AC was employed as the reference standard. Average %-differences in measured activity between the CT corrected PET and the PET corrected with the other AC methods were calculated.ResultsThe phantom housing and the liquid compartment were both visible and distinguishable from each other in the Dixon images and allowed the segmentation of a phantom-specific MR-based AC. Compared to the CT-AC PET, average differences in measured activity in the whole water compartment in the phantom of −0.3%, 9.4%, and −24.1% were found for Dixon phantom MR-AC, MR-AC, and NoWall-AC based PET, respectively. Average differences near the phantom wall in the homogeneous region were −0.3%, 6.6%, and −34.3%, respectively. Around the rods, activity differed from the CT-AC PET by 0.7%, 8.9%, and −45.5%, respectively.ConclusionThe presented phantom material is visible using standard MR sequences, and thus, supports the use of standard, phantom-independent MR measurements for MR-AC in PET/MRI phantom studies.

Probing the myelin water compartment with a saturation-recovery, multi-echo gradient-recalled echo sequence.

To investigate the effect of varying levels of -weighting on the evolution of the complex signal from white matter in a multi-echo gradient-recalled echo (mGRE) saturation-recovery sequence. Analysis of the complex signal evolution in an mGRE sequence allows the contributions from short- and long- components to be separated, thus providing a measure of the relative strength of signals from the myelin water, and the external and intra-axonal compartments. Here we evaluated the effect of different levels of -weighting on these signals, expecting that the previously reported, short of the myelin water would lead to a relative enhancement of the myelin water signal in the presence of signal saturation. Complex, saturation-recovery mGRE data from the splenium of the corpus callosum from 5 healthy volunteers were preprocessed using a frequency difference mapping (FDM) approach and analyzed using the 3-pool model of complex signal evolution in white matter. An increase in the apparent as a function of echo time was demonstrated, but this increase was an order of magnitude smaller than that expected from previously reported myelin water -values. This suggests the presence of magnetization transfer and exchange effects which counteract the -weighting. Variation of the amplitude in a saturation-recovery mGRE sequence can be used to modulate the relative strength of signals from the different compartments in white matter, but the modulation is less than predicted from previously reported -values.

How much do human and livestock actually contribute to steroids emission and surface water pollution from past to the future: A global research

A comprehensive global inventory of past, present, and future steroid emissions was firstly developed based on the global 5′ × 5′ grids relevant data available. From 1970 to 2070, the growth rate of the annual global steroid emission was relatively stable around 10%. At present (in 2015), the global steroid emissions was 18,270 t, with 17% contributed by humans. Almost one-third of total animal emissions have been occurring in India and Brazil. India also had the highest value of human steroid emissions. Regions with highest steroid emissions were concentrated between 10° ~ 35° N and 70° ~ 90° E. The increase of sewage treatment rates can effectively reduce the total quantity of steroids entering the environment, especially for some developing countries. But the “technology bonus” from sewage treatment process will be exhausted until to 2030. Meanwhile, global surface water pollution was predicted based on steroid emissions into water compartment and on the digital river network with annual river discharge. The modelling results show that steroids are widely distributed across the globe, with concentrations mostly below 100 ng/L. However, if no proper treatment measures for animal excretions, in another 100 years, the range of the surface water contaminated by steroids will increase by 1.2 times. The Nile River resulted as the most polluted among the eight world's longest and famous rivers during the whole period investigated. Various measured concentrations worldwide validated our modelling result. The global steroid emission inventory and surface water pollution from past to the future will stand as an important data and knowledge base for the management of pollution from different types of steroids at global and regional level.

Long-term ecotoxicological effects of ciprofloxacin in combination with caffeine on the microalga Raphidocelis subcapitata.

Ciprofloxacin (CIP) is an antimicrobial "pseudo-persistent" in aquatic ecosystems. Once dispersed in the water compartments, it can also affect the microalgae. Thus, the evaluation of its long-term ecotoxicological effects is necessary. CIP interactions with other pharmaceuticals are not well known. In this study, we investigated the toxic effects of CIP alone and combined with caffeine (CAF), using the modified Gompertz model parameters and the chlorophyll-a production of the microalga Raphidocelis subcapitata as endpoints, throughout a 16-day exposure assay. The exposure to CIP alone led to significant reductions of the growth rate and the cell density of the microalgae compared to control groups. The combination with CAF lowered the adverse effects of CIP to R. subcapitata. However, as the toxicity is dynamic, our results indicated that the toxic effects in respect to the studied endpoints changed throughout the exposure period, reinforcing the need for longer-term ecotoxicity assessments.

Influence of the selected physicochemical properties of the active substances of plant protection products on the results of their model exposure assessment in the surface water compartment

Influence of the selected physicochemical properties of the active substances of plant protection products on the results of their model exposure assessment in the surface water compartment

Identification of water compartments in spinal cords by 2 H double quantum filtered NMR.

In 2 H double quantum filtered (DQF) NMR, the various water compartments are characterized by their different residual quadrupolar interactions. The spectral separation between the different signals enables the measurement of the relaxation of each compartment and the magnetization transfer (MT) between them. In the current study, five water compartments were identified in the 2 H DQF spectra of porcine spinal cord. The most prominent signal was the pair of satellites with a quadrupolar splitting of about 550 Hz. 2 H DQF MRI optimized for the 550 Hz quadrupolar splitting indicated that this signal originated mainly from the white matter and it was assigned to the myelin water. This splitting does not change upon changing the orientation of the spinal cord relative to the magnetic field, indicating a liquid crystalline nature. Another site exhibiting splitting of about 1500 Hz was assigned to collagenous connective tissue. The narrow central peak was assigned to a combination of intra- and inter-axonal water. The assignment of the other two sites is not certain and requires further study. The rates of MT between the various sites were recorded.

Computational Probing of Temperature-Dependent Unfolding of a Small Globular Protein: From Cold to Heat Denaturation

Fully atomistic replica exchange molecular dynamics simulations are performed to compute the stability curve of a small globular protein as accurately as possible. To investigate the individual roles of the protein and water parts, we compute the conformational entropy change of this protein directly from the simulation ensembles. This entropy calculation enables complete separations of the unfolding changes of enthalpy and the entropy into their own protein and hydration components. From this decomposition, we are able to determine the main thermodynamic factors governing the cold and heat unfolding events: the cold and heat unfolding events are largely driven by the hydration enthalpy gain and the protein conformational entropy gain, respectively. This computational study discloses several temperature-dependent unfolding thermodynamic behaviors of the protein and water compartments and establishes their unique relationship. Upon unfolding, the changes of enthalpy and entropy in the protein part are all positive convex functions of temperature, whereas the equivalent changes in the water part are all negative concave functions of temperature. Hence, these two mutually opposing effects from the protein and water parts dictate the thermodynamics of unfolding. Furthermore, consistent with the temperature-dependent behaviors of the protein part, the changes of the solvent-accessible surface area and the radius of gyration of the protein upon unfolding are also convex functions of temperature. Hence, all these new temperature dependences, combined together, pave the way to unveiling the thermodynamic and structural features of protein denaturation events at various temperature conditions.

Speciation and quantification of organotin compounds in Lagos harbour, Nigeria

ABSTRACT The application of organotin-based antifouling compounds in the harbour during repairing and painting of ships in Nigeria harbour is a common practice in the maintenance wing of the dockyard. These antifouling chemicals are extremely toxic to aquatic life. As a result of dearth of data on the levels of organotin compounds in the West African coast including Lagos harbour, a study was undertaken to profile organotin compounds, in Lagos Dockyard harbour, Nigeria. The sediment and water samples were collected for two years (2016–2018) covering both the dry and wet seasons. A cold extraction technique by ultrasonication was used for sediments collected and a liquid-liquid separation technique was applied to water samples and later cleaned up by the use of silica gel-based packed column. The six organotin compounds considered in this work are Monobutyltin (MBT), Dibutyltin (DBT), Tributyltin (TBT), Monophenyltin (MPhT), Diphenyltin (DPhT), Triphenyltin (TPhT) were analysed by using an optimised high-performance liquid chromatography (HPLC). The result of the analysis on the sediment showed that the concentration of the organotin compounds (OTCs) ranges from 0.008 ± 0.00 to 272.710 ± 100.2 (ng/g) in MBT, 0.001 ± 0.00 to 69.780 ± 42.01 (ng/g) in DBT, 0.002 ± 0.00 to 7.110 ± 0.45 (ng/g) in TBT, 0.046 ± 0.01 to 76.210 ± 4.00 (ng/g) in MPhT, 0.070 ± 0.01 to 11.520 ± 0.62 (ng/g) in DPhT and 0.006 ± 0.00 to 2.330 ± 0.04 (ng/g) in TPhT. Higher values of OTCs were recorded during the wet season than the dry season and this was attributed to the dredging of harbour and remobilisation of organotin compounds from sediments into the water compartment. Principal Component Analysis (PCAs), Cluster Analysis (CA) and correlation analysis provided evidence for the interaction among these contaminants and possible sources of the contaminants. More so, the study showed that the degradation of these organotin compounds into their metabolites was governed by the influence of specific microorganisms. Therefore, regular monitoring of harbour was recommended for public safety.

An integral insight into pollen wall development: involvement of physical processes in exine ontogeny in Calycanthus floridus L., with an experimental approach.

We aimed to understand the underlying mechanisms of development in the sporopollenin-containing part of the pollen wall, the exine, one of the most complex cell walls in plants. Our hypothesis is that distinct physical processes, phase separation and micellar self-assembly, underpinexine development by taking the molecular building blocks, determined and synthesised by the genome, through several phase transitions. To test this hypothesis, we traced each stage of microspore development in Calycanthus floridus with transmission electron microscopy and then generated invitro experimental simulations corresponding to every developmental stage. The sequence of structures observed within the periplasmic space around developing microspores starts with spherical units, which are rearranged into columns to then form rod-like units (the young columellae) and, finally, white line centred endexine lamellae. Phase separation precedes each developmental stage. The set of experimental simulations, obtained as self-assembled micellar mesophases formed at the interface between lipid and water compartments, was the same: spherical micelles; columns of spherical micelles; cylindrical micelles; and laminate micelles, separated by gaps, resembling white-lined lamellae. Thus, patterns simulating structures observed at the main stages of exine development in C.floridus were obtained from invitro experiments, and hence purely physicochemical processes can construct exine-like patterns. This highlights the important part played by physical processes that are not under direct genomic control and share influence on the emerging ultrastructure with the genome during exine development. These findings suggest that a new approach to ontogenetic studies, including a consideration of physical factors, is required for a better understanding of developmental processes.

Bioelectrical impedance (BIA) compared to dual energy x-ray (DXA) in elderly patients admitted with acute pneumonia.

Rationale: In stress-metabolic conditions, we know that lean body mass (LBM) decreases and that change in water compartments is significant. Accordingly, weight is not an optimal variable for monitoring, and the aim of this investigation was to elucidate if bioelectrical impedance analysis (BIA) could be of use for that purpose compared to Dual Energy X-ray (DXA) as the golden standard, and to investigate the importance of fasting for the BIA measurements. Furthermore to establish if Phase Angle is of use as an inflammation marker.

P.408 Electroconvulsive therapy induces immediate changes in the extraneurite water compartment: a restriction spectrum imaging study

P.408 Electroconvulsive therapy induces immediate changes in the extraneurite water compartment: a restriction spectrum imaging study

In vivo investigation of the multi-exponential T2 decay in human white matter at 7 T: Implications for myelin water imaging at UHF.

Multi-component T2 mapping using a gradient- and spin-echo (GraSE) acquisition has become standard for myelin water imaging at 3 T. Higher magnetic field strengths promise signal-to-noise ratio benefits but face specific absorption rate limits and shortened T2 times. This study investigates compartmental T2 times in vivo and addresses advantages and challenges of multi-component T2 mapping at 7 T. We acquired 3D multi-echo GraSE data in seven healthy adults at 7 T, with three subjects also scanned at 3 T. Stimulated echoes arising from B1+ inhomogeneities were accounted for by the extended phase graph (EPG) algorithm. We used the computed T2 distributions to determine T2 times that identify different water pools and assessed signal-to-noise and fit-to-noise characteristics of the signal estimation. We compared short T2 fractions and T2 properties of the intermediate water pool at 3 T and 7 T. Flip angle mapping confirmed that EPG accurately determined the larger B1+ inhomogeneity at 7 T. Multi-component T2 analysis demonstrated shortened T2 times at 7 T compared with 3 T. Fit-to-noise and signal-to-noise ratios were improved at 7 T but depended on B1+ homogeneity. Adjusting the shortest T2 to 8 ms and the T2 threshold that separates different water compartments to 20 ms yielded short T2 fractions at 7 T that conformed to 3 T data. Short T2 fractions in myelin-rich white matter regions were lower at 7 T than at 3 T, and higher in iron-rich structures. Adjusting the T2 compartment boundaries was required due to the shorter T2 relaxation times at 7 T. Shorter echo spacing would better sample the fast decaying signal but would increase peripheral nerve stimulation. Multi-channel transmission will improve T2 measurements at 7 T. We used a multi-echo 3D GraSE sequence to characterize the multi-exponential T2 decay at 7 T. We adapted T2 parameters for evaluation of the short T2 fraction. Obtained 7 T multi-component T2 maps were in good agreement with 3 T data.

Resistance Training Improves a Cellular Health Parameter in Obese Older Women: A Randomized Controlled Trial.

Ribeiro, AS, Schoenfeld, BJ, dos Santos, L, Nunes, JP, Tomeleri, CM, Cunha, PM, Sardinha, LB, and Cyrino, ES. Resistance training improves a cellular health parameter in obese older women: a randomized controlled trial. J Strength Cond Res 34(10): 2996-3002, 2020-Phase angle (PhA) is a viable indicator of cellular health, with higher values reflecting better cellularity, cell membrane integrity, and cell function. Adaptive responses to resistance training (RT) on PhA may be important in obese older people. The main purpose of the present study was to investigate the effects of 8 weeks of RT on PhA in obese older women. Thirty-three obese older women (68.1 ± 5.7 years, 71.6 ± 10.1 kg, 154.5 ± 6.7 cm, 30.0 ± 4.1 kg·m, and 45.0 ± 6.0% body fat) were randomly allocated into 1 of 2 groups: a training group that performed the RT program (TG, n = 18) or a nonexercise control group (CG, n = 15). The whole-body RT consisted of an 8-week RT program involving 8 exercises performed for 3 sets of 8-12 repetitions 3 times a week. Anthropometric, body fat and fat-free mass, PhA, total body water (TBW), intracellular water (ICW), and extracellular water compartments were performed at before and after training. After the intervention period, the TG presented greater increases (p < 0.05) than CG for fat-free mass (TG = +1.3% and CG = -0.3%), TBW (TG = +2.0% and CG = -1.7%), ICW (TG = +3.1% and CG = -1.9%), and PhA (TG = +3.4% and CG = -1.4%), and lower values for percentage of body fat (TG = -1.3% and CG = +0.9%) and bioimpedance resistance (TG = -4.6% and CG = +2.3%). Our results suggest that 8 weeks of RT improves PhA-a cellular health parameter-in obese older women.

Temporal offset between precipitation and water uptake of Mediterranean pine trees varies with elevation and season

For climate models that use paleo-environment data to predict future climate change, tree-ring isotope variations are one important archive for the reconstruction of paleo-hydrological conditions. Due to the rather complicated pathway of water, starting from precipitation until its uptake by trees and the final incorporation of its components into tree-ring cellulose, a closer inspection of seasonal variations of tree water uptake is important. In this study, branch and needle samples of two pine species (Pinus pinaster and Pinus nigra subsp. laricio) and several water compartments (precipitation, creek, soil) were sampled over a two-year period and analyzed for the temporal variations of their oxygen and hydrogen stable isotope ratios (δ18O and δ2H) at five sites over an elevation gradient from sea level to around 1600 m a.s.l. on the Mediterranean island of Corsica (France). A new model was established to disentangle temporal relationships of source water uptake of trees. It uses a calculation method that incorporates the two processes mostly expected to affect source water composition: mixing of waters and evaporation. The model results showed that the temporal offset from precipitation to water uptake is not constant and varies with elevation and season. Overall, seasonal source water origin was shown to be dominated by precipitation from autumn and spring. While autumn precipitation was a more important water source for trees growing at mid- (~800–1000 m a.s.l) and high-elevation (~1600 m a.s.l.) sites, trees at coastal sites mostly took up water from late winter and spring. These findings show that predicted decreases in precipitation amounts during the wet season in the Mediterranean can have strong impacts on water availability for pine trees, especially at higher elevations.

Developing boron isotopes to elucidate shale weathering in the critical zone

To further develop boron isotopes as a tool for understanding shale weathering, we explored patterns of boron concentrations and isotopes across the forested Susquehanna Shale Hills Critical Zone Observatory (CZO). We present boron measurements for all watershed components that provided a foundation for examining water-rock interactions in a shale dominated watershed, including water compartments (e.g., precipitation, stream water, groundwater) and solid compartments (e.g., soil, bedrock, stream sediments, suspended load, and leaf litter). Results show boron isotopes (δ11B) in the bedrock (− 4.6‰) and soil (− 5.9 to - 4.2‰) were very similar. All waters were enriched in 11B by comparison: precipitation (7.2 to 22.6‰), stream (10.3 to 15.5‰), and groundwater (2.2 to 17.4‰). Modeling revealed that isotopic fractionation observed in the surface water and groundwater could mainly be explained by water-rock interactions including clay mineral dissolution (e.g., chlorite) and coprecipitation/adsorption processes (e.g., coatings on illite particles), likely in the near surface soils (~2 m deep). We found that leaching, the loss of boron from vegetation to stream water, plays a secondary role. Specifically, such leaching likely contributes the equivalent of 10 to 26% of the B fluxes from the watershed outlet. Boron mass balance between bedrock and precipitation inputs and the exported flux of dissolved and solid pools identified a “missing” isotopically light solid flux (δ11B of −12.2 ± 5.3‰ at ~4.4 ± 3.8 mol/ha/y of B; uncertainty reported as 2 SD). We did not sample any pool with this isotopic signature. Here our data suggest the composition of this pool is more likely related to precipitation of secondary clays rather than adsorption or (co)precipitation on Fe oxides. We propose two hypotheses to explain the missing light B pool: 1) a significant portion of the particles carrying the missing 10B are not sampled because they enter groundwater at depth and are transported out of the catchment under the stream; and/or 2) the inputs and outputs of boron are not operating at steady state in the catchment today, suggesting that the missing boron particles were lost in the past in proportions higher than today. When this B budget is paired with studies of δ26Mg and δ56Fe from Shale Hills, both of which also show missing isotopic pools, the pattern indicates a fundamental gap in understanding of shale weathering. We concluded that light B particles, presumably generated in the upper soils, are likely transported deep beneath the surface in the groundwater system or episodically in the past through riverine fluxes.

Quantifying effects of increased hydroperiod on wetland nutrient concentrations during early phases of freshwater restoration of the Florida Everglades

Wetland restoration requires managing long‐term changes in hydroperiod and ecosystem functions. We quantified relationships among spatiotemporal variability in wetland hydrology and total phosphorus (TP) and its stoichiometric relationships with total organic carbon (TOC:TP) and total carbon (TC:TP) and total nitrogen (TN:TP) in water, flocculent organic matter (floc), periphyton, sawgrass (Cladium jamaicense), and soil during early phases of freshwater wetland restoration—water year (WY) 2016 (1 May, 2015 to 30 April, 2016) to WY 2019—in Everglades National Park (ENP, Homestead, FL, U.S.A.). Wetland hydroperiod increased by 87 days, following restoration actions and rainfall events that increased median stage in the upstream source canal. Concentrations of TP were highest and most variable at sites closest (&lt;1 km) to canal inputs and upstream wetland sources of legacy P. Surface water TOC:TP and TN:TP ratios were highest in wetlands &gt;1 km downstream of the canal in wet season 2015 with spatial variability reflecting disturbances including droughts, fires, and freeze events. The TP concentrations of flocculent soil surface particles, periphyton, sawgrass, and consolidated soil declined, and TC:TP and TN:TP ratios increased (except soil) logarithmically with downstream distance from the canal. We measured abrupt increases in periphyton (wet season 2018) and sawgrass TP (wet season 2015 and 2018) at sites &lt;1 km from the canal, likely reflecting legacy TP loading. Our results suggest restoration efforts that increase freshwater inflow and hydroperiod will likely change patterns of nutrient concentrations among water and organic matter compartments of wetlands as a function of nutrient legacies.