Search

Sub-daily variations might significantly impact the estimates of GHG emissions from lakes and ponds. The objectives of this study are (i) to quantify sub-daily variations of the emissions of CO 2 , CH 4, and N 2 O from two urban ponds (Silex and Pêcheries) in the city of Brussels, (ii) to quantify if the sub-daily variations of GHG emissions were significant compared to their seasonal variations and to inter-pond variations among 20 other ponds in the city of Brussels. The partial pressure of CO 2 (pCO 2 ), CH 4 concentration, and N 2 O saturation level (%N 2 O) were measured hourly from dawn to dusk in the Pêcheries turbid-water pond and in the Silex clear-water pond during the four seasons in 2023-2024. pCO 2 followed the day-night cycle of photosynthesis in spring and summer but was more erratic in winter and fall. The variations of CH 4 concentration and %N 2 O were on most occasions erratic and difficult to attribute systematically to specific biogeochemical processes. The sub-daily variations of computed GHG emissions were mostly driven by variability in wind speed that usually peaked around mid-day. The comparison with previously acquired seasonal and inter-pond data (n = 22) showed that sub-daily variations of GHG fluxes were lower than seasonal variations, which were in turn lower than inter-pond variations. Consequently, to design sampling strategies to reduce the uncertainty on the estimate of CO 2 , CH 4 , and N 2 O emissions a priority should be given to describe inter-system variability, followed by seasonal variability, and lastly sub-daily variability, in the context of the environmental management of inland waters, including urban ponds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background/Objectives : Cytokine storm in severe COVID-19 is responsible for irreversible tissue damage and death. Soluble mediators from the TNF superfamily, their correlation with clinical outcome, and the use of TNF receptors as a potent predictor for clinical outcome were evaluated. Methods : Severe COVID-19 patients had the levels of soluble mediators from the TNF superfamily quantified and categorized according to the clinical outcome (death versus survival). Statistical modeling was performed to predict clinical outcomes. Results : COVID-19 patients have elevated serum levels from the TNF superfamily. Regardless of sex and age, the sTNFRI levels were observed to be significantly higher in deceased patients from the first weeks following the onset of symptoms. We analyzed hematological parameters and inflammatory markers, and there was a difference between the groups for the following factors: erythrocytes, hemoglobin, hematocrit, leukocytes, neutrophils, band cells, lymphocytes, monocytes, CRP, IL-8, IFN-γ, IL-10, IL-6, IL-4, IL-2, leptin MIF sCD40L, and sTNFRI ( p < 0.05). A post hoc analysis showed an inferential capacity over 70% for some hematological markers, CRP, and inflammatory mediators in deceased patients. sTNFRI was strongly associated with death, and the sTNFRI/sTNFRII ratio differed between outcomes ( p < 0.001; power above 90%), highlighting the impact of these proteins on clinical results. The final logistic model, including sTNFRI/sTNFRII and CRP, indicated high sensitivity, specificity, accuracy, and an eight-fold higher odds ratio for an unfavorable outcome. Conclusions : The joint use of the sTNFRI/sTNFRII ratio with CRP proves to be a promising tool to assist in the clinical management of patients hospitalized for COVID-19.

Freshwaters have been recognized as important sources of greenhouse gases (GHG) to the atmosphere. However, urban ponds have received little attention even though their number is increasing due to expanding urbanisation globally. Ponds are frequently associated to urban green spaces that provide several ecosystemic services such as cooling local climate, regulating the water cycle, and acting as small carbon sinks This study aims to identify and understand the processes producing GHGs (CO 2 , CH 4 , and N 2 O) in the urban ponds of the temperate European city of Brussels in Belgium. 22 relatively small ponds (0.1-4.6 ha) surrounded by contrasted landscape (strictly urban, bordered by cropland or by forest), were sampled during four seasons in 2021-2022. The mean ± standard deviation was 3,667 ± 2,904 ppm for the partial pressure of CO 2 (pCO 2 ), 2,833 ± 4,178 nmol L -1 for CH 4 , and 273 ± 662% for N 2 O saturation level (%N 2 O). Relationships of GHGs with oxygen and water temperature suggest that biological processes controlled pCO 2 , CH 4 concentration and%N 2 O. However, pCO 2 was also controlled by external inputs as indicated by the higher values of pCO 2 in the smaller ponds, more subject to external inputs than larger ones. The opposite was observed for CH 4 concentration that was higher in larger ponds, closer to the forest in the city periphery, and with higher macrophyte cover. N 2 O concentrations, as well as dissolved inorganic nitrogen, were higher closer to the city center, where atmospheric nitrogen deposition was potentially higher. The total GHG emissions from the Brussels ponds were estimated to 1kT CO 2 -eq per year and were equivalent to the carbon sink of urban green spaces., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A number of species of Chydorus Leach, 1816 (Crustacea: Cladocera) need improvements in their taxonomy much more than any other genus within the family Chydoridae Dybowsky & Grochowski, 1894 emend. Frey, 1967, which makes the systematics of the genus still a puzzle that lacks several pieces. Here, we redescribe the African species Chydorus tilhoi Rey & Saint-Jeans, 1969 and compare its morphology with that of Chydorus sphaericus (O.F. Mller, 1776). The two taxa might be easily differentiated because C. tilhoi has a single and relatively large major head pore with a wide rim, labral keel elongated with a large spine, and postabdomen with postanal part elongated, narrowing distally and with denticles near its anal margin, organized in groups. These morphological traits are absent in C. sphaericus. Chydorus tilhoi and C. sphaericus also differ in the morphology of the first (Inner Distal Lobe setae), third (exopodite proportion), and fifth (exopodite shape) limbs. Based on the literature and our observations, the limb morphology of C. tilhoi has important similarities with that of C. breviceps, C. nitidulus and C. dentifer, and their translocation to a new genus seems to be a fundamental piece in the puzzle of Chydorus.

Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that >70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing the pH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m -2 d -1 in mangroves and 57 ± 104 mmol m -2 d -1 in saltmarshes) was the major term in blue carbon budgets. However, substantial amounts of fixed carbon remain unaccounted for. Concurrently, alkalinity outwelling was similar or higher than sediment carbon burial and is therefore a significant but often overlooked carbon sequestration mechanism., (© 2023. The Author(s).)

In the study and treatment of psychosis, emotional intelligence (EI) and thinking styles are important patient characteristics for successful outcomes in clinical intervention. Anticipation of unpredictable stimuli (AUS) may be understood as an anomalous perception and anomalous cognition in which an individual supposedly senses and recognizes future stimuli in an unexpected way, also referred to as "hunches or premonitions." This examined the roles of EI and thinking styles in AUSs in convenience samples of healthy participants ( n = 237) versus patients diagnosed with psychosis ( n = 118). We adjusted several quadratic and exponential regression models according to the obtained functions. Group means were also compared to examine differences in EI scores for participants with psychosis compared to healthy participants. In the healthy group, EI predicted AUSs with a weight between 42% and 58%. Thinking styles were not correlated with AUSs. However, EI was not correlated with AUSs in the clinical group. Patients with psychosis tended to score higher on AUSs and lower on EI and thinking styles compared to participants in the healthy group. We discuss EI as a variable that can contextualize some anomalous perceptions which are otherwise difficult to classify or measure within the classic psychosis continuum model., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)

Natural lakes are thought to be globally important sources of greenhouse gases (CO 2 , CH 4 , and N 2 O) to the atmosphere although nearly no data have been previously reported from Africa. We collected CO 2 , CH 4 , and N 2 O data in 24 African lakes that accounted for 49% of total lacustrine surface area of the African continent and covered a wide range of morphology and productivity. The surface water concentrations of dissolved CO 2 were much lower than values attributed in current literature to tropical lakes and lower than in boreal systems because of a higher productivity. In contrast, surface water-dissolved CH 4 concentrations were generally higher than in boreal systems. The lowest CO 2 and the highest CH 4 concentrations were observed in the more shallow and productive lakes. Emissions of CO 2 may likely have been substantially overestimated by a factor between 9 and 18 in African lakes and between 6 and 26 in pan-tropical lakes.

COVID-19, also known as coronavirus disease 2019, is an infectious viral disease caused by SARS-CoV-2, a novel coronavirus. Since its emergence, its epidemiology has been explored; however, for some regions of the world, COVID-19's behavior, incidence, and impact remain unclear. In continental nations like Brazil, this lack of knowledge results in nonuniform control, prevention, and treatment measures, which can be controversial in some locations. This study aimed to describe the epidemiological profile of patients with COVID-19 in the macroregion of Triângulo Sul in the state of Minas Gerais (MG), Brazil. Between March 25 and October 21, 2020, data were collected and statistically analyzed from 395 hospitalized patients in the city of Uberaba, MG, suspected to have moderate or severe forms of the disease. Of the 395 suspected cases, 82% were confirmed to be positive for COVID-19. The mean age of positive patients was 58.4 years, and 60.76% were male. Following these patients throughout their hospitalization, a mortality rate of 31.3% was observed. In the population positive for COVID-19, the risk of death increased by 4% for each year of the patient's age. Likewise, the older the patient, the longer their hospitalization and the higher the risk of developing acute respiratory failure. Among the treatments tested in patients, heparin was associated with protection against mortality, and the absence of anticoagulant use was linked to a more than six times greater risk of death. Finally, comorbidities in patients with COVID-19 were positively correlated with increased hospitalization time. In summary, this study revealed that age, presence of comorbidities, length of hospitalization, and drug treatment considerably altered COVID-19's lethality. To understand infection rates and the factors involved in COVID-19's lethality, knowledge of the local epidemiology is necessary., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Silva, Rodrigues, Abadia, Alves da Silva, Andrade e Silva, Desidério, Farnesi-de-Assunção, Costa-Madeira, Barbosa, Bernardes e Borges, Hortolani Cunha, Pereira, Helmo, Lemes, Barbosa, Trevisan, Obata, Bueno, Mundim, Oliveira-Scussel, Monteiro, Ferreira, Machado, Ferreira-Paim, Moraes-Souza, da Silva, Rodrigues Júnior and Oliveira.)

While the emissions of methane (CH4) by natural systems have been widely investigated, CH4 aquatic sinks are still poorly constrained. Here, we investigated the CH4 cycle and its interactions with nitrogen (N), iron (Fe) and manganese (Mn) cycles in the oxic-anoxic interface and deep anoxic waters of a small, meromictic and eutrophic lake, during two summertime sampling campaigns. Anaerobic CH4 oxidation (AOM) was measured from the temporal decrease of CH4 concentrations, with the addition of three potential electron acceptors (NO3-, iron oxides (Fe(OH)3) and manganese oxides (MnO2)). Experiments with the addition of either 15N-labeled nitrate (15N-NO3-) or 15N-NO3- combined with sulfide (H2S), to measure denitrification, chemolithotrophic denitrification and anaerobic ammonium oxidation (anammox) rates, were also performed. Measurements showed AOM rates up to 3.8 µmol CH4 L-1 d-1 that strongly increased with the addition of NO3- and moderately increased with the addition of Fe(OH)3. No stimulation was observed with MnO2 added. Potential denitrification and anammox rates up to 63 and 0.27 µmol N2 L-1 d-1, respectively, were measured when only 15N-NO3- was added. When H2S was added, both denitrification and anammox rates increased. Altogether, these results suggest that prokaryote communities in the redoxcline are able to efficiently use the most available substrates., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Aquifers under agricultural areas are considered to be an indirect source of nitrous oxide emission (N 2 O) to the atmosphere, which is the greenhouse gas (GHGs) characterized with the highest global warning potential and acts as a stratospheric ozone depletion agent. Previous investigations performed in the Cretaceous Hesbaye chalk aquifer in Eastern Belgium suggested that the dynamics of N 2 O in the aquifer is controlled by overlapping biochemical processes such as nitrification and denitrification. The current study aims to obtain better insight concerning the factors controlling the distribution of N 2 O concentration along a vertical dimension in the aquifer, and to capture and quantify the occurrence of nitrification and denitrification processes in the groundwater system. Low-flow groundwater sampling technique was undertaken at different depths in the aquifer to collect groundwater samples aiming at obtaining information about ambient aquifer hydrogeochemical conditions and their effect on the accumulation of GHGs. Afterwards, laboratory stable isotope experiments, using NO 3 - and NH 4 + compounds labeled with heavy 15 N isotope, were applied to quantify the rates of nitrification and denitrification processes. Ambient studies suggest that the occurrence of N transformation was related to denitrification while laboratory incubation experiments did not detect it. Such controversial results might be explained by the discrepancy between real aquifer conditions and lab design studies. Thus, additional in situ tracer experiments should be carried out in areas where natural groundwater fluxes do not flush the injected tracer too rapidly. In addition, it would be useful to conduct microbiological studies to obtain better insight into the nature of subsurface biofilm biotope., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In the ferruginous and anoxic early Earth oceans, photoferrotrophy drove most of the biological production before the advent of oxygenic photosynthesis, but its association with ferric iron (Fe 3+ ) dependent anaerobic methane (CH 4 ) oxidation (AOM) has been poorly investigated. We studied AOM in Kabuno Bay, a modern analogue to the Archean Ocean (anoxic bottom waters and dissolved Fe concentrations > 600 µmol L -1 ). Aerobic and anaerobic CH 4 oxidation rates up to 0.12 ± 0.03 and 51 ± 1 µmol L -1  d -1 , respectively, were put in evidence. In the Fe oxidation-reduction zone, we observed high concentration of Bacteriochlorophyll e (biomarker of the anoxygenic photoautotrophs), which co-occurred with the maximum CH 4 oxidation peaks, and a high abundance of Candidatus Methanoperedens, which can couple AOM to Fe 3+ reduction. In addition, comparison of measured CH 4 oxidation rates with electron acceptor fluxes suggest that AOM could mainly rely on Fe 3+ produced by photoferrotrophs. Further experiments specifically targeted to investigate the interactions between photoferrotrophs and AOM would be of considerable interest. Indeed, ferric Fe 3+ -driven AOM has been poorly envisaged as a possible metabolic process in the Archean ocean, but this can potentially change the conceptualization and modelling of metabolic and geochemical processes controlling climate conditions in the Early Earth.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Inland waters (rivers, lakes and ponds) are important conduits for the emission of terrestrial carbon in Arctic permafrost landscapes. These emissions are driven by turnover of contemporary terrestrial carbon and additional pre-aged (Holocene and late-Pleistocene) carbon released from thawing permafrost soils, but the magnitude of these source contributions to total inland water carbon fluxes remains unknown. Here we present unique simultaneous radiocarbon age measurements of inland water CO 2 , CH 4 and dissolved and particulate organic carbon in northeast Siberia during summer. We show that >80% of total inland water carbon was contemporary in age, but pre-aged carbon contributed >50% at sites strongly affected by permafrost thaw. CO 2 and CH 4 were younger than dissolved and particulate organic carbon, suggesting emissions were primarily fuelled by contemporary carbon decomposition. Our findings reveal that inland water carbon emissions from permafrost landscapes may be more sensitive to changes in contemporary carbon turnover than the release of pre-aged carbon from thawing permafrost.

In order to investigate the possible use of the dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) ratio as a stress indicator of Posidonia oceanica a method for the determination of these quantities was developed for this type of material. •The method relies on gas chromatography with headspace technique, instead of the purge-and-trap technique commonly used.•The method allows the determination of both DMSP and DMSO on the same sample.•This method allows to quantify DMSP, DMSO and DMSP:DMSO ratio for calibration curves with a coefficient of variation around 2% and a relative error around 2% and within the ranges natural variability of DMSP and DMSO in P. oceanica leaf tissue. Preliminary tests showed that DMSP in P. oceanica leaf tissue ranged from 20 to 200 μmol g -1 of fresh weight (FW) and 2 to 5 μmol g fw -1 for DMSO. The DMSP:DMSO ratio ranged from 2 to 40. The quantifications were conducted with different mixtures of DMSP and DMSO by measurements of DMSP and DMSO in the same sample of P. oceanica leaf tissue.

Carbon evasion from rivers is an important component of the global carbon cycle. The intensification of anthropogenic pressures on hydrosystems requires studies of human-impacted rivers to identify and quantify the main drivers of carbon evasion. In 2016 and 2017, four field campaigns were conducted in the Seine River network characterized by an intensively cropped and highly populated basin. We measured partial pressures of carbon dioxide (pCO 2 ) in streams or rivers draining land under different uses at different seasons. We also computed pCO 2 from an existing data set (pH, water temperature and total alkalinity) going back until 1970. Here we report factors controlling pCO 2 that operate at different time and space scales. In our study, the Seine River was shown to be supersaturated in CO 2 with respect to the atmospheric equilibrium, as well as a source of CO 2 . Our results suggest an increase in pCO 2 from winter to summer in small streams draining forests (from 1670 to 2480 ppm), croplands (from 1010 to 1550 ppm), and at the outlet of the basin (from 2490 to 3630 ppm). The main driver of pCO 2 was shown to be dissolved organic carbon (DOC) concentrations (R 2  = 0.56, n = 119, p < 0.05) that are modulated by hydro-climatic conditions and groundwater discharges. DOC sources were linked to land use and soil, mainly leaching into small upstream streams, but also to organic pollution, mainly found downstream in larger rivers. Our long-term analysis of the main stream suggests that pCO 2 closely mirrors the pattern of urban water pollution over time. These results suggest that factors controlling pCO 2 operate differently upstream and downstream depending on the physical characteristics of the river basin and on the intensity and location of the main anthropogenic pressures. The influence of these controlling factors may also differ over time, according to the seasons, and mirror long term changes in these anthropogenic pressures.

We investigated plankton metabolism and its influence on carbon dioxide (CO 2 ) dynamics in a central Amazon floodplain lake (Janauacá, 3°23' S, 60°18' W) from September 2015 to May 2016, including a period with exceptional drought. We made diel measurements of CO 2 emissions to the atmosphere with floating chambers and depth profiles of temperature and CO 2 partial pressure (pCO 2 ) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism. Overnight community respiration (CR), and gross primary production (GPP) rates were higher in clear chambers and positively correlated with chlorophyll-a (Chl-a). CO 2 air-water fluxes varied over 24-h periods with changes in thermal structure and metabolism. Most net daily CO 2 fluxes during low water and mid-rising water at the wind exposed site were into the lake as a result of high rates of photosynthesis. All other measurements indicated net daily release to the atmosphere. Average GPP rates (6.8gCm -2 d -1 ) were high compared with other studies in Amazon floodplain lakes. The growth of herbaceous plants on exposed sediment during an exceptional drought led to large carbon inputs when these areas were flooded, enhancing CR, pCO 2 , and CO 2 fluxes. During the period when the submerged herbaceous vegetation decayed phytoplankton abundance increased and photosynthetic uptake of CO 2 occurred. While planktonic metabolism was often autotrophic (GPP:CR>1), CO 2 out-gassing occurred during most periods investigated indicating other inputs of carbon such as sediments or soils and wetland plants., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The influence of abiotic and biotic variables on the concentration of dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO), were investigated during an annual cycle in 2016 in the Belgian Coastal Zone (BCZ, North Sea). We reported strong seasonal variations in the concentration of these compounds linked to the phytoplankton succession with high DMS(P,O) producers (mainly Phaeocystis globosa) occurring in spring and low DMS(P,O) producers (various diatoms species) occurring in early spring and autumn. Spatial gradients of DMS and DMSP were related to those of phytoplankton biomass itself related to the inputs of nutrients from the Scheldt estuary. However, the use of a relationship with Chlorophyll-a (Chl-a) concentration is not sufficient to predict DMSP. Accounting for the phytoplankton composition, two different DMSP versus Chl-a correlations could be established, one for diatoms and another one for Phaeocystis colonies. We also reported high nearshore DMSO concentrations uncoupled to Chl-a and DMSP concentrations but linked to high suspended particulate matter (SPM) presumably coming from the Scheldt estuary as indicated by the positive relationship between annual average SPM and salinity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This work reviews applications of stable isotope analysis to the studies of transport and transformation of N species in groundwater under agricultural areas. It summarizes evidence regarding factors affecting the isotopic composition of NO 3 - , NH 4 + and N 2 O in subsurface, and discusses the use of 11 B, 18 O, 13 C, 34 S, 87 Sr/ 86 Sr isotopes to support the analysis of δ 15 N values. The isotopic composition of NO 3 - , NH 4 + and N 2 O varies depending on their sources and dynamics of N cycle processes. The reported δ 15 N-NO 3 - values for sources of NO 3 - are: soil organic N - +3‰-+8‰, mineral fertilizers - -8‰-+7‰; manure/household waste - +5‰ to +35‰. For NH 4 + sources, the isotopic signature ranges are: organic matter - +2.4-+4.1‰, rainwater - -13.4-+2.3‰, mineral fertilizers - -7.4-+5.1‰, household waste - +5-+9‰; animal manure - +8-+11‰. For N 2 O, isotopic composition depends on isotopic signatures of substrate pools and reaction rates. δ 15 N values of NO 3 - are influenced by fractionation effects occurring during denitrification (ɛ=5-40‰), nitrification (ɛ=5-35‰) and DNRA (ɛ not reported). The isotopic signature of NH 4 + is also affected by nitrification and DNRA as well as mineralization (ɛ=1‰), sorption (ɛ=1-8‰), anammox (ɛ=4.3-7.4‰) and volatilization (ɛ=25‰). As for the N 2 O, production of N 2 O leads to its depletion in 15 N, whereas consumption - to enrichment in 15 N. The magnitude of fractionation effects occurring during the considered processes depends on temperature, pH, DO, C/NO 3 - ratio, size of the substrate pool, availability of electron donors, water content in subsoil, residence time, land use, hydrogeology. While previous studies have accumulated rich data on isotopic composition of NO 3 - in groundwater, evidence remains scarce in the cases of NH 4 + and N 2 O. Further research is required to consider variability of δ 15 N-NH 4 + and δ 15 N-N 2 O in groundwater across agricultural ecosystems., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This work aims to (1) identify the most conductive conditions for the generation of greenhouses gases (GHGs) in groundwater (e.g., hydrogeological contexts and geochemical processes) and (2) evaluate the indirect emissions of GHGs from groundwater at a regional scale in Wallonia (Belgium). To this end, nitrous oxide (N 2 O), methane (CH 4 ) and carbon dioxide (CO 2 ) concentrations and the stable isotopes of nitrate (NO 3 - ) and sulphate were monitored in 12 aquifers of the Walloon Region (Belgium). The concentrations of GHGs range from 0.05μg/L to 1631.2μg/L for N 2 O, 0μg/L to 17.1μg/L for CH 4 , and 1769 to 100,514ppm for the partial pressure of CO 2 (pCO 2 ). The highest average concentrations of N 2 O and pCO 2 are found in a chalky aquifer. The coupled use of statistical techniques and stable isotopes is a useful approach to identify the geochemical conditions that control the occurrence of GHGs in the aquifers of the Walloon Region. The accumulation of N 2 O is most likely due to nitrification (high concentrations of dissolved oxygen and NO 3 - and null concentrations of ammonium) and, to a lesser extent, initial denitrification in a few sampling locations (medium concentrations of dissolved oxygen and NO 3 - ). The oxic character found in groundwater is not prone to the accumulation of CH 4 in Walloon aquifers. Nevertheless, groundwater is oversaturated with GHGs with respect to atmospheric equilibrium (especially for N 2 O and pCO 2 ); the fluxes of N 2 O (0.32kgN 2 O-NHa -1 y -1 ) and CO 2 (27kgCO 2 Ha -1 y -1 ) from groundwater are much lower than the direct emissions of N 2 O from agricultural soils and fossil-fuel-related CO 2 emissions. Thus, indirect GHG emissions from the aquifers of the Walloon Region are likely to be a minor contributor to atmospheric GHG emissions, but their quantification would help to better constrain the nitrogen and carbon budgets., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We report a data-set of CO 2 , CH 4 , and N 2 O concentrations in the surface waters of the Meuse river network in Belgium, obtained during four surveys covering 50 stations (summer 2013 and late winter 2013, 2014 and 2015), from yearly cycles in four rivers of variable size and catchment land cover, and from 111 groundwater samples. Surface waters of the Meuse river network were over-saturated in CO 2 , CH 4 , N 2 O with respect to atmospheric equilibrium, acting as sources of these greenhouse gases to the atmosphere, although the dissolved gases also showed marked seasonal and spatial variations. Seasonal variations were related to changes in freshwater discharge following the hydrological cycle, with highest concentrations of CO 2 , CH 4 , N 2 O during low water owing to a longer water residence time and lower currents (i.e. lower gas transfer velocities), both contributing to the accumulation of gases in the water column, combined with higher temperatures favourable to microbial processes. Inter-annual differences of discharge also led to differences in CH 4 and N 2 O that were higher in years with prolonged low water periods. Spatial variations were mostly due to differences in land cover over the catchments, with systems dominated by agriculture (croplands and pastures) having higher CO 2 , CH 4 , N 2 O levels than forested systems. This seemed to be related to higher levels of dissolved and particulate organic matter, as well as dissolved inorganic nitrogen in agriculture dominated systems compared to forested ones. Groundwater had very low CH 4 concentrations in the shallow and unconfined aquifers (mostly fractured limestones) of the Meuse basin, hence, should not contribute significantly to the high CH 4 levels in surface riverine waters. Owing to high dissolved concentrations, groundwater could potentially transfer important quantities of CO 2 and N 2 O to surface waters of the Meuse basin, although this hypothesis remains to be tested., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Travertine deposition is a landscape-forming process, usually building a series of calcareous barriers differentiating the river flow into a series of cascades and ponds. The process of carbonate precipitation is a complex relationship between biogenic and abiotic causative agents, involving adapted microbial assemblages but also requiring high levels of carbonate saturation, spontaneous degassing of carbon dioxide and slightly alkaline pH. We have analysed calcareous crusts and water chemistry from four sampling sites along the Hoyoux River and its Triffoy tributary (Belgium) in winter, spring, summer and autumn 2014. Different surface textures of travertine deposits correlated with particular microenvironments and were influenced by the local water flow. In all microenvironments, we have identified the cyanobacterium Phormidium incrustatum (Nägeli) Gomont as the organism primarily responsible for carbonate precipitation and travertine fabric by combining morphological analysis with molecular sequencing (16S rRNA gene and ITS, the Internal Transcribed Spacer fragments), targeting both field populations and cultures to exclude opportunistic microorganisms responding favourably to culture conditions. Several closely related cyanobacterial strains were cultured; however, only one proved identical with the sequences obtained from the field population by direct PCR. This strain was the dominant primary producer in the calcareous deposits under study and in similar streams in Europe. The dominance of one organism that had a demonstrated association with carbonate precipitation presented a valuable opportunity to study its function in construction, preservation and fossilisation potential of ambient temperature travertine deposits. These relationships were examined using scanning electron microscopy and Raman microspectroscopy.

This work reviews the concentrations, the dynamics and the emissions of nitrous oxide (N 2 O) in groundwater. N 2 O is an important greenhouse gas (GHG) and the primary stratospheric ozone depleting substance. The major anthropogenic source that contributes to N 2 O generation in aquifers is agriculture because the use of fertilizers has led to the widespread groundwater contamination by inorganic nitrogen (N) (mainly nitrate, NO 3 - ). Once in the aquifer, this inorganic N is transported and affected by several geochemical processes that produce and consume N 2 O. An inventory of dissolved N 2 O concentrations is presented and the highest concentration is about 18.000 times higher than air-equilibrated water (up to 4004μg N L -1 ). The accumulation of N 2 O in groundwater is mainly due to denitrification and to lesser extent to nitrification. Their occurrence depend on the geochemical (e.g., NO 3 - , dissolved oxygen, ammonium and dissolved organic carbon) as well as hydrogeological parameters (e.g., groundwater table fluctuations and aquifer permeability). The coupled understanding of both parameters is necessary to gain insight on the dynamics and the emissions of N 2 O in groundwater. Overall, groundwater indirect N 2 O emissions seem to be a minor component of N 2 O emissions to the atmosphere. Further research might be devoted to evaluate the groundwater contribution to the indirect emissions of N 2 O because this will help to better constraint the N 2 O global budget and, consequently, the N budget., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We sampled the water column of the Dendre stone pit lake (Belgium) in spring, summer, autumn and winter. Depth profiles of several physico-chemical variables, nutrients, dissolved gases (CO 2 , CH 4 , N 2 O), sulfate, sulfide, iron and manganese concentrations and δ 13 C-CH4 were determined. We performed incubation experiments to quantify CH 4 oxidation rates, with a focus on anaerobic CH 4 oxidation (AOM), without and with an inhibitor of sulfate reduction (molybdate). The evolution of nitrate and sulfate concentrations during the incubations was monitored. The water column was anoxic below 20 m throughout the year, and was thermally stratified in summer and autumn. High partial pressure of CO 2 and CH 4 and high concentrations of ammonium and phosphate were observed in anoxic waters. Important nitrous oxide and nitrate concentration maxima were also observed (up to 440 nmol L -1 and 80 μmol L -1 , respectively). Vertical profiles of δ 13 C-CH 4 unambiguously showed the occurrence of AOM. Important AOM rates (up to 14 μmol L -1  d -1 ) were observed and often co-occurred with nitrate consumption peaks, suggesting the occurrence of AOM coupled with nitrate reduction. AOM coupled with sulfate reduction also occurred, since AOM rates tended to be lower when molybdate was added. CH 4 oxidation was mostly aerobic (∼80% of total oxidation) in spring and winter, and almost exclusively anaerobic in summer and autumn. Despite important CH 4 oxidation rates, the estimated CH 4 fluxes from the water surface to the atmosphere were high (mean of 732 μmol m -2  d -1 in spring, summer and autumn, and up to 12,482 μmol m -2  d -1 in winter)., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Methane is the second most important greenhouse gas contributing to climate warming. The open ocean is a minor source of methane to the atmosphere. We report intense methane emissions from the near-shore southern region of the North Sea characterized by the presence of extensive areas with gassy sediments. The average flux intensities (~130 μmol m(-2) d(-1)) are one order of magnitude higher than values characteristic of continental shelves (~30 μmol m(-2) d(-1)) and three orders of magnitude higher than values characteristic of the open ocean (~0.4 μmol m(-2) d(-1)). The high methane concentrations (up to 1,128 nmol L(-1)) that sustain these fluxes are related to the shallow and well-mixed water column that allows an efficient transfer of methane from the seafloor to surface waters. This differs from deeper and stratified seep areas where there is a large decrease of methane between bottom and surface by microbial oxidation or physical transport. Shallow well-mixed continental shelves represent about 33% of the total continental shelf area, so that marine coastal methane emissions are probably under-estimated. Near-shore and shallow seep areas are hot spots of methane emission, and our data also suggest that emissions could increase in response to warming of surface waters.

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels.

The microbial community composition in meromictic Lake Kivu, with one of the largest CH4 reservoirs, was studied using 16S rDNA and ribosomal RNA (rRNA) pyrosequencing during the dry and rainy seasons. Highly abundant taxa were shared in a high percentage between bulk (DNA-based) and active (RNA-based) bacterial communities, whereas a high proportion of rare species was detected only in either an active or bulk community, indicating the existence of a potentially active rare biosphere and the possible underestimation of diversity detected when using only one nucleic acid pool. Most taxa identified as generalists were abundant, and those identified as specialists were more likely to be rare in the bulk community. The overall number of environmental parameters that could explain the variation was higher for abundant taxa in comparison to rare taxa. Clustering analysis based on operational taxonomic units (OTUs at 0.03 cutoff) level revealed significant and systematic microbial community composition shifts with depth. In the oxic zone, Actinobacteria were found highly dominant in the bulk community but not in the metabolically active community. In the oxic-anoxic transition zone, highly abundant potentially active Nitrospira and Methylococcales were observed. The co-occurrence of potentially active sulfur-oxidizing and sulfate-reducing bacteria in the anoxic zone may suggest the presence of an active yet cryptic sulfur cycle.

Iron-rich (ferruginous) ocean chemistry prevailed throughout most of Earth's early history. Before the evolution and proliferation of oxygenic photosynthesis, biological production in the ferruginous oceans was likely driven by photoferrotrophic bacteria that oxidize ferrous iron {Fe(II)} to harness energy from sunlight, and fix inorganic carbon into biomass. Photoferrotrophs may thus have fuelled Earth's early biosphere providing energy to drive microbial growth and evolution over billions of years. Yet, photoferrotrophic activity has remained largely elusive on the modern Earth, leaving models for early biological production untested and imperative ecological context for the evolution of life missing. Here, we show that an active community of pelagic photoferrotrophs comprises up to 30% of the total microbial community in illuminated ferruginous waters of Kabuno Bay (KB), East Africa (DR Congo). These photoferrotrophs produce oxidized iron {Fe(III)} and biomass, and support a diverse pelagic microbial community including heterotrophic Fe(III)-reducers, sulfate reducers, fermenters and methanogens. At modest light levels, rates of photoferrotrophy in KB exceed those predicted for early Earth primary production, and are sufficient to generate Earth's largest sedimentary iron ore deposits. Fe cycling, however, is efficient, and complex microbial community interactions likely regulate Fe(III) and organic matter export from the photic zone.

We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007-mid rainy season, September 2007-late dry season, June 2008-early dry season, and April 2009-late rainy season). The partial pressure of CO2 (pCO2) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11,213 ppm and 14,213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m(-2) d(-1), which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m(-2) d(-1) (∼46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs.

The Oubangui is a major tributary of the Congo River. We describe the biogeochemistry of contrasting tributaries within its central catchment, with watershed vegetation ranging from wooded savannahs to humid rainforest. Compared to a 2-year monitoring record on the mainstem Oubangui, these tributaries show a wide range of biogeochemical signatures, from highly diluted blackwaters (low turbidity, pH, conductivity, and total alkalinity) in rainforests to those more typical for savannah systems. Spectral analyses of chromophoric dissolved organic matter showed wide temporal variations in the Oubangui compared to spatio-temporal variations in the tributaries, and confirm that different pools of dissolved organic carbon are mobilized during different hydrological stages. δ(13)C of dissolved inorganic carbon ranged between -28.1‰ and -5.8‰, and was strongly correlated to both partial pressure of CO2 and to the estimated contribution of carbonate weathering to total alkalinity, suggesting an important control of the weathering regime on CO2 fluxes. All tributaries were oversaturated in dissolved greenhouse gases (CH4, N2O, CO2), with highest levels in rivers draining rainforest. The high diversity observed underscores the importance of sampling that covers the variability in subcatchment characteristics, to improve our understanding of biogeochemical cycling in the Congo Basin.

We developed a module describing the dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) dynamics, including biological transformations by phytoplankton and bacteria, and physico-chemical processes (including DMS air-sea exchange). This module was integrated in the MIRO ecological model and applied in a 0D frame in the Southern North Sea (SNS). The DMS(P) module is built on parameterizations derived from available knowledge on DMS(P) sources, transformations and sinks, and provides an explicit representation of bacterial activity in contrast to most of existing models that only include phytoplankton process (and abiotic transformations). The model is tested in a highly productive coastal ecosystem (the Belgian coastal zone, BCZ) dominated by diatoms and the Haptophyceae Phaeocystis, respectively low and high DMSP producers. On an annual basis, the particulate DMSP (DMSPp) production simulated in 1989 is mainly related to Phaeocystis colonies (78%) rather than diatoms (13%) and nanoflagellates (9%). Accordingly, sensitivity analysis shows that the model responds more to changes in the sulfur:carbon (S:C) quota and lyase yield of Phaeocystis. DMS originates equally from phytoplankton and bacterial DMSP-lyase activity and only 3% of the DMS is emitted to the atmosphere. Model analysis demonstrates the sensitivity of DMS emission towards the atmosphere to the description and parameterization of biological processes emphasizing the need of adequately representing in models both phytoplankton and bacterial processes affecting DMS(P) dynamics. This is particularly important in eutrophied coastal environments such as the SNS dominated by high non-diatom blooms and where empirical models developed from data-sets biased towards open ocean conditions do not satisfactorily predict the timing and amplitude of the DMS seasonal cycle. In order to predict future feedbacks of DMS emissions on climate, it is needed to account for hotspots of DMS emissions from coastal environments that, if eutrophied, are dominated not only by diatoms.

A lack of appropriate proxies has traditionally hampered our ability to distinguish riverine organic carbon (OC) sources at the landscape scale. However, the dissection of C 4 grasslands by C 3 -enriched riparian vegetation, and the distinct carbon stable isotope signature (δ 13 C) of these two photosynthetic pathways, provides a unique setting to assess the relative contribution of riparian and more distant sources to riverine C pools. Here, we compared δ 13 C signatures of bulk sub-basin vegetation (δ 13 C VEG ) with those of riverine OC pools for a wide range of sites within two contrasting river basins in Madagascar. Although C 3 -derived carbon dominated in the eastern Rianala catchment, consistent with the dominant vegetation, we found that in the C 4 -dominated Betsiboka basin, riverine OC is disproportionately sourced from the C 3 -enriched riparian fringe, irrespective of climatic season, even though δ 13 C VEG estimates suggest as much as 96% of vegetation cover in some Betsiboka sub-basins may be accounted for by C 4 biomass. For example, δ 13 C values for river bed OC were on average 6.9 ± 2.7‰ depleted in 13 C compared to paired estimates of δ 13 C VEG . The disconnection of the wider C 4 -dominated basin is considered the primary driver of the under-representation of C 4 -derived C within riverine OC pools in the Betsiboka basin, although combustion of grassland biomass by fire is likely a subsidiary constraint on the quantity of terrestrial organic matter available for export to these streams and rivers. Our findings carry implications for the use of sedimentary δ 13 C signatures as proxies for past forest-grassland distribution and climate, as the C 4 component may be considerably underestimated due to its disconnection from riverine OC pools.

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 "Seagrasses productivity. From genes to ecosystem management," is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwater acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as "pristine site" where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.

Background: A time series of 4 consecutive years of measurements of the partial pressure of CO2 (pCO2) in the Scheldt estuarine plume is used here to estimate net ecosystem production (NEP)., Results: NEP in the Scheldt estuarine plume is estimated from the temporal changes of dissolved inorganic carbon (DIC). The strong seasonal variations of NEP are consistent with previous reports on organic carbon dynamics in the area. These variations are related to successive phytoplankton blooms that partly feed seasonally variable heterotrophy the rest of the year. On an annual time scale the Scheldt estuarine plume behaves as a net heterotrophic system sustained with organic carbon input from the Scheldt inner estuary and the Belgian coast. During one of the years of the time-series the estuarine plume behaved annually as a net autotrophic system. This anomalous ecosystem metabolic behaviour seemed to result from a combination of bottom-up factors affecting the spring phytoplankton bloom (increased nutrient delivery and more favourable incoming light conditions). This net autotrophy seemed to lead to a transient aa accumulation of organic carbon, most probably in the sediments, that fed a stronger heterotrophy the following year., Conclusion: The present work highlights the potential of using pCO2 data to derive detailed seasonal estimates of NEP in highly dynamic coastal environments. These can be used to determine potential inter-annual variability of NEP due to natural climatic oscillations or due to changes in anthropogenic impacts.

Objective: Under the hypothesis that the anatomic relationship of the tibialis anterior tendon and extensor retinaculum of the foot and ankle is relevant to the clinical aspects of a tear in that tendon, we assessed the anatomic details of these structures using MRI in cadavers and evaluated MRI in patients with a tibialis anterior tendon tear., Materials and Methods: Seven cadaveric feet underwent detailed MRI using standard and oblique coronal planes with respect to the course of the tibialis anterior tendon and extensor retinaculum. Cadaveric sections subsequently provided an anatomic correlation. MR images of seven patients with tibialis anterior tendon tear were analyzed by consensus of two musculoskeletal radiologists., Results: Imaging-anatomic correlations allowed identification of the tibialis anterior tendon and extensor retinaculum. The tendon passed through three tunnels formed by the superior extensor retinaculum, oblique superomedial, and oblique inferomedial limbs of the inferior extensor retinaculum. Of seven patients with the tendon tear, three patients had complete tears and four patients had partial tears. In all partial tears, the level of the tear was at the ankle joint, corresponding to the approximate level of the oblique superomedial limb. In all complete tears, the proximal ends of torn tendons were retracted to a level below the oblique superomedial limb. In all tears, the oblique superomedial limb surrounding the torn tendon was seen with thickening in four patients and enhancement after IV gadolinium injection in two patients. Other findings included a bulbous appearance or swelling of the torn tendon in two complete and two partial tears and fluid collections within the tendon sheath and in an area confined by the extensor retinaculum in four patients., Conclusion: The relationship of the tibialis anterior tendon and extensor retinaculum is well depicted on MRI, even in patients with a tibialis anterior tendon tear, and is clinically relevant to the tear of this tendon.

Arthropathy is a major clinical manifestation in primary hemochromatosis, typically affecting the metacarpophalangeal joints. Hip arthropathy is not uncommon, with radiologic features resembling osteoarthritis or calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. We describe the MR imaging findings of the hip in a patient with severe hip arthropathy and primary hemochromatosis and correlate them with the histopathologic findings. MR imaging showed severe degenerative changes, with large subchondral cysts and subchondral sclerosis in the femoral head and acetabulum. There was conspicuous correlation between MR imaging and pathologic findings of the resected femoral head. However, MR imaging failed to reveal intra-articular iron.

Patellar retinaculum and cruciate and collateral ligaments are major passive stabilizers of the knee joint. Injuries to these ligaments may alter the overall articular motion and lead to instability. Experienced as a sense of the knee "giving way," instability is a predisposing factor for recurring injuries and osteoarthritis. This section presents a practical imaging approach to knee instability based on a major injury to a specific ligament, with routine radiographic and magnetic resonance imaging findings discussed in detail. Common patterns of multiple ligamentous injuries are noted in appropriate subsections.

Objective: The purpose of this study was to determine the reliability of standard axial MR images alone in the diagnosis of meniscal tears of the knee and in combination with other imaging planes., Materials and Methods: Sixty-two patients (55 men, seven women; age range, 23-68 years) with a prior MRI examination who underwent arthroscopic surgery of the knee during a 1-year period were included in the study group. Images were independently reviewed for identification of meniscal tears by two musculoskeletal radiologists blinded to arthroscopic findings. Sequences for meniscal evaluation included axial fat-saturated fast spin-echo proton density, coronal fat-saturated fast spin-echo proton density, and sagittal fast spin-echo proton density with 4- to 5-mm slice thicknesses. Imaging groups for evaluation were axial, coronal, sagittal, axial and sagittal, axial and coronal, and coronal and sagittal. Observers reported a confidence level for the presence or absence of meniscal tear in all imaging groups based on a 5-point scale. Statistical analysis considered medial and lateral menisci separately., Results: Forty patients had medial meniscal tears, and 16 had lateral meniscal tears at arthroscopy. For medial and lateral meniscal tears, the accuracy (79% and 71%, respectively) of imaging in the axial plane was comparable to other imaging groups but the mean confidence levels (2.82 and 3.00, respectively) were low. In one patient, the axial plane alone correctly showed that no tear was present. No statistically significant difference was observed between imaging plane groups of both menisci in the diagnosis of meniscal tears (p > 0.05). The axial plane increased the accuracy of sagittal and coronal planes of lateral meniscus when combined., Conclusion: In standard knee MRI examinations, the axial imaging plane may be valuable for the detection and characterization of meniscal tears.

A patient with histologically proven gliomatosis cerebri presented with a normal choline level but a markedly abnormal elevated myo-inositol level on magnetic resonance (MR) spectroscopy. We describe the case presentation, imaging findings (in particular, the unique MR spectroscopic pattern), and their significance regarding the diagnosis of this relatively rare neoplasm.

The postoperative shoulder may be evaluated with various imaging modalities, including radiography, ultrasonography, computed tomography, and magnetic resonance (MR) imaging, each of which has advantages and disadvantages. For optimal soft-tissue visualization, MR imaging and MR arthrography are widely used. Several factors, however, may decrease the accuracy of MR imaging in the evaluation of the postoperative shoulder. These factors include surgical distortions of native anatomy, changes in the signal intensity of tissues, and image degradation caused by metallic artifacts. To maximize the accuracy of MR imaging, the radiologist must select the most appropriate pulse sequences and techniques for the given anatomic structure and the suspected postoperative condition. To avoid magnetic susceptibility artifacts at MR imaging, inversion recovery may be used instead of fat saturation, and fast spin-echo sequences may be used instead of conventional spin-echo sequences or gradient-echo sequences. MR arthrography is most useful for optimal delineation of the rotator cuff, capsulolabral structures, and tendon defects. To achieve accurate image interpretation, the radiologist must be familiar with the arthroscopic and the open surgical techniques currently used to repair internal derangements of the glenohumeral joint, as well as with the typical imaging findings in each postoperative situation., (Copyright RSNA, 2004)

This article described many of the causes of monoarticular arthritis that are encountered in clinical practice. Although radiologists have relied on conventional radiography and bone scintigraphy, additional imaging methods have been introduced, such as MR imaging, CT scanning, and US. These methods improve visualization of intra-articular and periarticular soft tissue structures and are helpful in the guidance of arthrocentesis, drainage procedures, or percutaneous biopsies. Imaging findings always should be correlated with clinical abnormalities, and, when appropriate, joint fluid analysis.