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The radium isotopes (224Ra, t½ = 3.7 d;223Ra, t½ =11.5 d; 228Ra, (t½ = 5.7 y); 226Ra, t½ =1600 y) are well established tracers for the detection and quantification of submarine groundwater discharge (SGD). In the Eckernförde Bay (Western Baltic Sea) SGD associated with pock marks have been observed at many locations on the seabed (~ 20-25m water depths). In order to investigate the spatial and temporal SGD variability we repeatedly measured between 2016 and 2020 the radium (224Ra, 223Ra, 228Ra, 226Ra) distribution in the water column of the Eckernförde Bay and the adjacent Kiel Bay. In general, the water-column radium profiles are characterized by relatively low radium concentrations in the upper water column (~

In many cases, shallow coastal lagoons are, on the one hand, vulnerable habitats for birds and marine ecosystems and, on the other hand, threatened by discharging nutrient-laden surface waters and groundwater. In particular, the localization and quantification of submarine groundwater discharge (SGD) is of key concern in this regard. The presented study aimed at investigating SGD into a vulnerable coastal lagoon that is strongly impacted by evaporation applying a multi-tracer approach. The joint application of radionuclides (222Rn, 223Ra, 224Ra), stable water isotopes (δ18O, δ2H) and the water salinity as environmental water tracers allowed evaluating the suitability of the individual parameters in this specific type of environment. Whilst stable isotope and salinity data were difficult to construe in terms of SGD occurrence due to the intense impact of evaporation, a radon mass balance allowed localising SGD areas within the lagoon and quantifying the related SGD flux rates. In addition, a 224Ra/223Ra ratio analysis revealed information on the apparent age of the discharged groundwater, and hence on the flushing intensity of the lagoon. Besides these site-specific results, the study allowed the following general conclusions regarding the suitability of the applied tracers: (i) we verified the suitability of a radon mass balance approach for proving/disproving SGD occurrence and quantifying SGD fluxes in shallow coastal lagoons strongly impacted by evaporation; (ii) we showed that the impact of evaporation may impede the use of water stable isotope and salinity data as SGD indicators in such specific environments; (iii) we demonstrated that the tidal impact on a lagoon water body during a sampling campaign can be compensated by adapting sampling schedule and cruise track to the tidal cycle.

BACKGROUND Diabetic foot ulcers (DFUs) are a devastating complication of diabetes and a leading cause of non-traumatic foot amputations. Traditional methods of monitoring and managing patients with diabetes, such as periodic in-person clinic visits, may not be sufficient for preventing DFUs and amputations. Continuous Remote Temperature Monitoring has the potential to capture the critical period before the foot ulcers develop and to improve outcomes by providing real-time data and early interventions. For the first time, the effectiveness of such a strategy to prevent DFUs and amputations among high-risk patients in a real-world commercial setting is reported. OBJECTIVE The aim of this study is to evaluate the effectiveness of a real-world continuous remote temperature monitoring program in preventing DFUs and amputations in patients with diabetes. METHODS In this retrospective analysis of a real-world continuous remote temperature monitoring program, 109 high risk patients identified by clinical providers from 15 geographically diverse private podiatry offices were analyzed. Patients received continuous remote monitoring socks as part of the program. The enrollment was based on medical necessity as decided by their managing physician. We evaluated data from up to 2 years before enrollment and up to 3 years during the program. Primary outcome was the rate of wound development. Secondary outcomes included amputation rate, severity of the foot ulcers, and the number of visits to an outpatient podiatry clinic after enrolling in the program. RESULTS We observed significantly lower rates of foot ulceration (relative risk reduction (RRR) 0.69; number needed to treat (NNT) 5.0; 95% CI 0.80, 0.53; p CONCLUSIONS Our findings suggested that a real-world continuous remote temperature monitoring program was an effective strategy to prevent DFU development and non-traumatic foot amputation among high-risk patients. CLINICALTRIAL WCG-IRB (1284366)

Elizabeth Brooks,1 Megan Burns,1 Ran Ma,2 Henk Jan Scholten,2 Shawn Becker3 1TTi Health Research and Economics, Westminster, MD, USA; 2Siren Care, Inc, San Francisco, CA, USA; 3Silvercat Advisors, LLC, Burlingame, CA, USACorrespondence: Megan BurnsTTi Health Research and Economics, 1231 Tech Ct Suite 201, Westminster, MD, 21157, USAEmail meganalexburns@gmail.comBackground: Foot temperature monitoring for the prevention and early detection of diabetic foot ulcers (DFU) is evidence-based and recommended in clinical practice. However, easy-to-use remote monitoring tools have been lacking, thereby preventing widespread adoption.Objective: To evaluate the cost-effectiveness of remote foot temperature monitoring (RFTM) (Siren’s Neurofabric™ Diabetic socks) in addition to standard of care (SoC) versus SoC alone for early detection of DFU with diabetic neuropathy and a moderate to high risk of DFU.Methods: A payer perspective decision-tree analysis was conducted to compare expected DFU occurrence and subsequent amputation rates and costs between treatment strategies over one year. Inputs in the model were sourced from publicly available literature and relevant health technology assessments. One-way sensitivity analyses were performed for each model variable.Results: In the base-case scenario, RFTM plus SoC was a dominant strategy compared to SoC alone. RFTM plus SoC was associated with cost savings of $38,593 per additional ulcer avoided versus SoC alone, and $8027 per patient per year on average compared to SoC alone. These results were highly robust to one-way sensitivity analysis; all scenarios remained dominant if compliance was ≥ 13%.Conclusion: RFTM is a cost-effective addition to SoC in patients with diabetic neuropathy at a moderate-to-high risk of DFU and subsequent amputation. Further, reduction in DFU and associated complications may result in improvements in the patient’s quality of life and mental health. Future studies are needed to evaluate the compliance and reduction of DFU occurrence in patients on RFTM.Keywords: diabetes mellitus, diabetic foot, technology assessment, biomedical, cost-benefit analysis, cost savings, decision trees

Mapping radon (222Rn) distribution patterns in the coastal sea is a widely applied method for localizing and quantifying submarine groundwater discharge (SGD). While the literature reports a wide range of successful case studies, methodical problems that might occur in shallow wind-exposed coastal settings are generally neglected. This paper evaluates causes and effects that resulted in a failure of the radon approach at a distinct shallow wind-exposed location in the Baltic Sea. Based on a simple radon mass balance model, we discuss the effect of both wind speed and wind direction as causal for this failure. We show that at coastal settings, which are dominated by gentle submarine slopes and shallow waters, both parameters have severe impact on coastal radon distribution patterns, thus impeding their use for SGD investigation. In such cases, the radon approach needs necessarily to allow for the impact of wind speed and wind direction not only during but also prior to the field campaign.

For millennia, humans have gravitated towards coastlines for their resource potential and as geopolitical centres for global trade. A basic requirement ensuring water security for coastal communities relies on a delicate balance between the supply and demand of potable water. The interaction between freshwater and saltwater in coastal settings is, therefore, complicated by both natural and human-driven environmental changes at the land–sea interface. In particular, ongoing sea-level rise, warming and deoxygenation might exacerbate such perturbations. In this context, an improved understanding of the nature and variability of groundwater fluxes across the land–sea continuum is timely yet remains out of reach. The flow of terrestrial groundwater across the coastal transition zone and the extent of freshened groundwater below the present-day seafloor are receiving increased attention in marine and coastal sciences because they likely represent a significant yet highly uncertain component of (bio)geochemical budgets and because of the emerging interest in the potential use of offshore freshened groundwater as a resource. At the same time, “reverse” groundwater flux from offshore to onshore is of prevalent socio-economic interest, as terrestrial groundwater resources are continuously pressured by over-pumping and seawater intrusion in many coastal regions worldwide. An accurate assessment of the land–ocean connectivity through groundwater and its potential responses to future anthropogenic activities and climate change will require a multidisciplinary approach combining the expertise of geophysicists, hydrogeologists, (bio)geochemists and modellers. Such joint activities will lay the scientific basis for better understanding the role of groundwater in societally relevant issues such as climate change, pollution and the environmental status of the coastal oceans within the framework of the United Nations Sustainable Development Goals. Here, we present our perspectives on future research directions to better understand land–ocean connectivity through groundwater, including the spatial distributions of the essential hydrogeological parameters, highlighting technical and scientific developments and briefly discussing the societal relevance of that connectivity in rapidly changing coastal oceans.

When rivers mix into the ocean, radium isotopes are released into the dissolved phase allowing us to apply these isotopes as powerful tracers of river plumes spreading into the ocean. We report 223Ra and 224Ra radium activities that were determined in the Amazon River mouth and along the Amazon plume that extends off the coasts of Brazil and French Guyana into the Atlantic Ocean. We summarize 223Ra and 224Ra data from AmasSeds (1991), AMANDES (GEOTRACES process study GApr01; 2007–2008) and M147 (2018) projects, which were conducted in different seasons corresponding to different Amazon discharge rates. We determined the 224Raex/223Ra activity ratios (AR) along the Amazon plume to derive apparent ages and to estimate the residence time of the Amazon waters on the Brazilian continental shelf. Our data suggest that it takes 9–14 d for the Amazon waters to reach the northern continental shelf off French Guyana and 12–21 d to reach the eastern part of the Brazilian continental shelf. These time scales are in good agreement with those derived from a high-resolution numerical simulation of the regional ocean dynamics. We do not find any relationship between the discharge rate of the Amazon River and the residence time of the waters on the Brazilian continental shelf, suggesting that the residence time of the Amazon waters is primarily driven by the ambient northwestward current. Using the apparent ages along the plume, we estimate an average velocity of 26 cm s−1 for the northward transport of the Amazon waters on the continental shelf.

The impact of submarine groundwater discharge (SGD) on coastal biogeochemistry is currently under intense investigation. SGD can impact diagenesis and in general act as a potential source of elements, especially dissolved carbon, to coastal surface waters. However, qualitative and quantitative assessments of SGD are challenging since it requires the identification of suitable geochemical tracers for the complex hydrological and biogeochemical processes in the subterranean estuary. In this communication, we report on combined investigations carried out in Königshafen Bay (North Frisian island Sylt, Germany), a tidal area in the eastern North Sea. Sampling encompassed vertical porewater gradients, and surface waters collected through transects in the bay, and in tidal cycles at the outlet of the bay. Potential surface and subterrestrial freshwater endmembers are used to assess the results. Besides major and minor elements, this study focuses on the stable carbon isotope composition of dissolved inorganic carbon (DIC) and the activity of radium (Ra) isotopes. Our main aim is to characterize the interaction between diagenesis and the composition of SGD, as well as the resulting impact on the carbon system of the water column, and, via tidal exchange extended to the coastal North Sea. Porewaters showed usually an increase of isotopically light DIC with depth and a freshening already in the top 50 cmbsf at some sites. This indicates that both, carbon diagenesis and mixing of seawater with fresh groundwaters at depth impact the distribution of DIC. The activities of the short-living Ra isotope (224Raex) were higher in the bay compared to the open North Sea. Porewater activities were up to 30 times higher than in the bay’s surface waters with a maximum development at intermediate salinities. In the water column at the outlet of the bay, 224Raex and 223Ra showed maximum activities during low tide as a consequence of the highest contribution of waters in contact with the sediments of the bay. Moreover, due to the high hydraulic gradient developed during low tide more contribution from potential endmembers enriched in Ra can be expected. Further work is on the way to quantify the impact of SGD on the tidal basin and the indirect role for the North Sea carbon system on different temporal and spatial scales. The investigations are supported by the DFG-project KiSNet, the BMBF project COOLSTYLE (CARBOSTORE), the DAAD, the DFG RTG Baltic TRANSCOAST, and the Leibniz IOW.

Mapping radon (

Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon and total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, and continental shelf scales in the Amazon region. Observations of salinity and radium isotopes in the creek indicated tidally driven groundwater exchange as the main source of carbon. Radium‐derived transport rates indicate that mangrove carbon is exported out of the continental shelf on timescales of 22 ± 7 d. Bicarbonate was the main form (82% ± 11%) of total dissolved carbon in all samples, followed by DOC (13% ± 12%) and CO2 (5% ± 4%). DIC (18.7 ± 15.7 mmol m−2 d−1) exceeded DOC (3.0 ± 4.1 mmol m−2 d−1) outwelling at all spatial scales. The interpretation of outwelling across the mangrove‐ocean continuum is related to the spatial and temporal scales investigated. At all scales, outwelling represented a major coastal carbon pathway driving bicarbonate storage in the ocean.

BACKGROUND Remote patient monitoring (RPM) devices are increasingly being used in caring for patients to reduce risks of complications. Temperature monitoring specifically has been shown in previous studies to provide a useful signal of inflammation that may help prevent foot ulcers. OBJECTIVE In this cross-sectional study, we evaluated utilization data for patients who were prescribed smart socks as remote temperature monitoring devices. METHODS This study evaluated data from a patient registry from January to July 2021. The utilization data, which were collected starting from the first full month since patients were prescribed the smart socks, were evaluated along with retention over time, the average time that the socks were worn, and the number of days that the socks were worn per month and per week. RESULTS A total of 160 patients wore the smart sock RPM device for 22 to 25 days per month on average. The retention rate was 91.9% (147/160) at the end of the 7-month period; a total of 13 patients were lost to follow-up during this period. The average number of days that the socks were worn per week was 5.8. The percentage of patients with a utilization rate of >15 days ranged from 79.7% (106/133) to 91.9% (125/136) each month. CONCLUSIONS This study shows a high level of utilization for a smart sock RPM device and a high compliance rate. A future prospective study on the clinical outcomes after the use of the smart socks may further solidify the idea of conducting temperature monitoring for foot ulcer prevention.

Background Lower extremity complications of diabetes represent major health care complications both in terms of cost and impact to quality of life for patients with diabetic peripheral neuropathy. Temperature monitoring has been shown in previous studies to provide a useful signal of inflammation that may indicate the early presence of a foot injury. Objective In this study, we evaluated the temperature data for patients that presented with a diabetic foot injury while using a sock-based remote temperature monitoring device. Methods The study abstracted data from patients who were enrolled in a remote temperature monitoring program (2020-2021) using a smart sock (Siren Care). In the study cohort, a total of 5 participants with a diabetes-related lower extremity injury during the study period were identified. In the second comparison cohort, a total of 26 patients met the criteria for monitoring by the same methods but did not present with a diabetes-related podiatric lower extremity injury during the same period. The 15-day temperature differential between 6 defined locations on each foot was the primary outcome measure among subjects who presented with a diagnosed foot injury. Paired t tests were used to compare the differences between the two groups. Results A significant difference in temperature differential (temperature measured in °F) was observed in the group that presented with a podiatric injury over the course of evaluation versus the comparator group that did not present with a podiatric injury. The average difference from all 6 measured points was 1.4 °F between the injury group (mean 3.6, SD 3.0) and the comparator group (mean 2.2, SD 2.5, t=–71.4, df=39; P Conclusions The results of this study suggest temperature monitoring in a sock form factor could be used to predict a developing foot injury. The continuous temperature monitoring system employed has implications for further algorithm development to enable early detection. The study was limited by a nonrandomized, observational design with limited injuries present in the study period. We look forward to further studies that will refine the predictive potential and confirm or refute the current promising data.

BACKGROUND Lower extremity complications of diabetes represent major health care complications both in terms of cost and impact to quality of life for patients with diabetic peripheral neuropathy. Temperature monitoring has been shown in previous studies to provide a useful signal of inflammation that may indicate the early presence of a foot injury. OBJECTIVE In this study, we evaluated the temperature data for patients that presented with a diabetic foot injury while using a sock-based remote temperature monitoring device. METHODS The study abstracted data from patients who were enrolled in a remote temperature monitoring program (2020-2021) using a smart sock (Siren Care). In the study cohort, a total of 5 participants with a diabetes-related lower extremity injury during the study period were identified. In the second comparison cohort, a total of 26 patients met the criteria for monitoring by the same methods but did not present with a diabetes-related podiatric lower extremity injury during the same period. The 15-day temperature differential between 6 defined locations on each foot was the primary outcome measure among subjects who presented with a diagnosed foot injury. Paired t tests were used to compare the differences between the two groups. RESULTS A significant difference in temperature differential (temperature measured in °F) was observed in the group that presented with a podiatric injury over the course of evaluation versus the comparator group that did not present with a podiatric injury. The average difference from all 6 measured points was 1.4 °F between the injury group (mean 3.6, SD 3.0) and the comparator group (mean 2.2, SD 2.5, t=–71.4, df=39; P CONCLUSIONS The results of this study suggest temperature monitoring in a sock form factor could be used to predict a developing foot injury. The continuous temperature monitoring system employed has implications for further algorithm development to enable early detection. The study was limited by a nonrandomized, observational design with limited injuries present in the study period. We look forward to further studies that will refine the predictive potential and confirm or refute the current promising data.

Highlights • Frequent sediment resuspension may have buffered D-Fe released from shelf sediments. • 228Ra was used to estimate trace element fluxes from the Chukchi shelf sediments. • The estimated sediment 228Ra flux ranks among the highest reported globally. • About 10–25% of the Chukchi shelf sediment Fe flux is exported to the Arctic Ocean. The Chukchi Sea is a primary site for shelf-ocean exchange in the Arctic region and modifies Pacific-sourced water masses as they transit via the Bering Strait into the Arctic Ocean. The aim of this study was to use radium and trace metal distributions to improve our understanding of biogeochemical cycles in the Bering and Chukchi Seas, and evaluate their potential response to future changes in the Arctic. We investigated the distributions of dissolved and total dissolvable trace metals (Cd, Fe, Ni, Cu, Zn, Mn, Co, and Pb) in the Bering and Chukchi Seas during spring. In addition, the long-lived radium isotopes (226Ra and 228Ra) were measured as tracers of benthic trace metal inputs. Trace metal concentrations, especially Fe and Mn, were highly elevated in Chukchi shelf waters compared with the open Arctic Ocean and Bering Strait. Trace metal, nutrient, and Ra patterns suggested that Fe, Mn, and Co concentrations were predominantly controlled by reductive benthic inputs, whereas the other trace metals were influenced by biological uptake and release processes. We propose that Fe, Mn, and Co in the Chukchi Sea are supplied from shelf sediments during winter overturning, and we combine the 228Ra fluxes with the distributions of Fe, Mn, and Co to provide a first estimate of their benthic fluxes in the region. The average benthic flux of 228Ra was 1.49 × 108 atoms m−2 d−1, which is among the highest rates reported globally. Estimated dissolved Fe (D-Fe) flux from the sediments was 2.5 μmol m−2 d−1, whereas D-Mn and D-Co fluxes were 8.0 μmol m−2 d−1 and 0.2 μmol m−2 d−1, respectively. The off-shelf transport of D-Fe to the Arctic Ocean is estimated to be about 10–25% of the benthic Fe flux, with the remainder retained on the shelf due to scavenging and/or phytoplankton uptake. Our results highlight the importance of the Chukchi Sea as a major source of the micro-nutrients to the Arctic Ocean, thereby supporting primary production. Long-term changes in factors that affect cross-shelf mixing, such as the observed reduction in ice cover, may therefore enhance shelf nutrient inputs and primary productivity in the Arctic.

Submarine groundwater discharge (SGD) acts as a source of fresh water and dissolved substances for coastal ecosystems. Evaluation of the actual controls on SGD and corresponding chemical fluxes require a closer understanding of the processes that take place in the mixing zone between SGD and the coastal waters. It is hypothesized that artificial infrastructures, like sediment channeling, may ease the hydrological connection between coastal aquifer and coastal bottom water. The resultant, increase of SGD, changes the residence time in the mixing zone, and thereby, reduces the impact of early diagenesis. The present study focuses on the distribution of SGD, including the characterization of different mixing zones in the urbanized Wismar Bay (WB), southern Baltic Sea. Short sediment cores were retrieved for geochemical porewaters and sediment analyses. Surface sea water samples were collected along across-shore transects in the WB. Besides major ions, Ba, Fe, and Mn, the water samples were analyzed for nutrients, dissolved inorganic carbon (DIC), stable isotopes (H, O, C, S), and Ra isotopes. Sediments were analyzed for C, N, S, Hg contents as well as reactive components (e.g. Fe, Mn, P) by HCl extractions. Organic matter mineralization rates, DIC, and SO4 fluxes for the sediment-water interface were modeled from porewater profiles. Shallow seismic techniques were applied to identify potential litho-morphological controls on SGD. Geochemical porewater data allow identification of active SGD sites in the WB. In the central part, the freshening of porewaters in the top surface sediments indicates the upward flow of SGD originating from a coastal aquifer. The acoustic profiles show that the bottom sediments in the central bay are under local impact of excavation, reducing the sediment thickness above the coastal aquifer. Overall, the impact of SGD on the coastal water body of the WB is diffuse and promoted by local anthropogenic activity. The water isotope composition of porewaters at this site are close to the local meteoric water line at Warnemünde (located 50 km east of the WB), suggesting a discharge of relatively modern fresh waters. The (isotope) hydrochemical composition of the fresh water discharging is controlled by water-rock interactions in the aquifer and modulated by intense diagenesis in the brackish surface sediments. Furthermore, the SGD facilitates the upward migration of elements and enhances their fluxes across the sediment-water interface, e.g. DIC concentrations in the fresh groundwater are further enhanced in the mixing zone, indicating that SGD is a potential source of excess CO2 in the investigated coastal waters.The investigations are supported by the DAAD, DFG RTS Baltic TRANSCOAST, KiSnet project, BONUS SEAMOUNT, FP7 EU Marie Curie career integration grant, DAM-MFG, and IOW.

The eutrophic lake Eichbaumsee, a ~ 1 km long and 280m wide (maximum water depth 16m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e. aeration plants, removal of dissolved phosphate by aluminium phosphate precipitation and by Benthophos adsorption) during the past ~ 15 years. Despite these treatments no long-term improvement of the water quality was observed and the lake water phosphate content continued to increase by e.g. ~ 350 kg phosphate per year between March 2016 and February 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphate (and other nutrients) are unknown.We investigated the phosphate fluxes from sediment pore water and groundwater into the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphate fluxes from pore water were calculated based on phosphate gradients using first Fick`s law. Stable water isotopes (δ2H, δ18O) were measured in the lake water, sediment pore water, interstitial waters in the banks surrounding the lake, the Elbe river and in three groundwater wells close to lake. Stable isotope (δ2H, δ18O) water mass balance models were used to compute water inflow/outflow to/from the lake.Our results revealed pore-water borne phosphate fluxes between – 0.07 mg/m²/d (i.e. slight phosphate uptake by the sediments) and 2.6 mg/m²/d (i.e. phosphate release to the lake). Assuming that the measured phosphate fluxes are temporarily and spatially representative for the whole lake, about 100 kg/a to 220 kg/a of phosphate is released from sediments. This amount is slightly lower than the observed phosphate increase of the lake water. Stable isotope signatures indicate a water exchange between the aquifer and the lake water. Based on stable isotope mass balances (δ2H, δ18O) we estimate an inflow of phosphate from the aquifer to the lake between 190 kg/a and 1400 kg/a. This inflow indicates that groundwater-born phosphate is as or even more important than phosphate supply via sediment pore-water. Our study suggests that groundwater may have an important impact on lake nutrient budgets.

Submarine groundwater discharge into coastal areas is a common global phenomenon and is rapidly gaining scientific interest due to its influence on marine biology and the coastal sedimentary environment, and it's potential as a future freshwater resource. We conducted an integrated study of hydroacoustic surveys combined with geochemical porewater and water column investigations at a well-known freshwater seep site in Eckernförde Bay (Germany).The location and distribution of pockmarks in this area have been the focus of many studies since their discovery in 1966 including numerous investigations of their geochemical, geological and geophysical behavior. Despite several intense and extensive research campaigns (e.g. Sub-GATE/CBBL) their internal morphology and structure presented in this study were poorly constrained to date. With recent advances in shallow high-frequency multibeam echosounder methods combined with highly accurately positioned sediment cores, we can provide new insights on the influence of shallow gas and freshwater on the formation and internal morphology of the pockmarks. We show that high-frequency multibeam data can be used to detect free shallow gas in areas of enhanced freshwater advection in muddy sediments. Intra-pockmarks, forming due to ascending gas and freshwater, pose a new form of ‘eyed’ pockmarks revealed by their acoustic backscatter response. Our data suggest that in muddy sediments morphological lows combined with a strong multibeam backscatter signal can be indicative of free shallow gas and the subsequent advection of freshwater.

Submarine groundwater discharge (SGD) is considered as an important route for water and dissolved material exchange between land and coastal seas. Both freshwater and (recirculated) seawater are referred to as SGD and may impact the composition and biogeochemical processes in coastal waters. The present study focuses on the identification and the spatial variability of SGD into the Wismar Bay, in the southern Baltic Sea. On across-shore transects covering Wismar Bay waters were sampled for analysis of Radium (Ra) isotopes, stable isotopes (H, O, C, S), dissolved inorganic carbon (DIC), nutrients and major cations. In addition, sediment cores were retrieved from several stations. The detection of short-living radium isotopes (223Ra and224Ra) in surface waters of the bay indicate benthic-pelagic coupling via pore water exchange with the water column that may be an indication for SGD. Moreover, enhanced concentration of dissolved manganese and barium, resulted from anoxic pore waters, were found in areas with higher Ra activity. Pore water profiles of salinity and major ions highlight the presence of freshwater about 50 cmbsf in sediments in the central part of the bay, probably related to the presence of a coastal aquifer. In contrast, other sediments demonstrate relatively constant pore water salinity distribution with increasing depth. Slight salinity maxima in almost all core at around 6 to 12 cmbsf seems to be relict from changing bottom water salinity in the past. The water isotope composition (δ18O, δ2H) of the low saline pore water is plot close to the local meteoric water line established for Warnemünde. Saline pore waters, in contrast, have water isotope composition aligned with southern Baltic Sea surface waters. The DIC concentrations increased with depths suggesting the mineralization of organic matter within the 50 cm sediments depth at all sides. Moreover, the values of DIC even exceeding the concentration found on the percolating fresh ground water. Thus, the overall contribution of elements to the coastal ecosystem is a function of the transport processes regulating element flux across the sediment-water interface.The investigation is supported by the DFG research training school Baltic TRANSCOAST, DAAD, and Leibniz IOW.

The analysis of natural radium-in-water activity concentrations is for two reasons of general interest: (1) radium in natural waters may pose a problem with regard to radiation protection and (2) radium isotopes in natural waters can be used as environmental tracers in hydrological studies. A state-of-the-art method for radium extraction from (generally large) water sample volumes is radium adsorption onto MnO2 coated acrylic fibers. In our study we comparatively evaluated four methodical approaches for post-extraction preparation of the fiber to allow gamma spectrometric measurements. The methods included (1) straightforward measurement of the loose fiber, (2) compressing the fiber after mixing it with an adhesive, (3) combustion of the fiber and embedding the ash in candlewax, and (4) leaching of the fiber and embedding the resulting precipitate in candlewax. The aim of the study was to compare the advantages and disadvantages of the four preparation approaches with respect to their individual practicability. Even though the methodical fiber preparation approaches have been suggested in the literature before (as cited in this paper), results of their direct practical comparison have not been presented yet. Our study revealed that balancing practical sample preparation effort against data reproducibility suggests a measurement of the compressed fiber applying an adhesive to be the preferable approach.

WC-Co hard metals are increasingly used in parts with more complex and highly fatigue loading situations. This requires a transition of material strength data provided by the manufacturer to the actual component. The method of the effectively loaded volume and surface has proven to work well for several static loading conditions and component sizes. This work provides evidence that this method can also be used with cyclic loading conditions. Specimen with three different effectively loaded volumes and surfaces have been exposed to monotonically increasing, as well as high cycle fatigue loads under four-point bending. The effectively loaded volumes and surfaces match the found characteristic fracture strengths as well as the logarithmic numbers of cycles to failure. A theoretical transition from the characteristic fracture strength to the fatigue limit across different geometries is demonstrated and matches the experimental data.

Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (223Ra, 224Ra, 226Ra and 228Ra) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water and solutes to the coastal ocean. In addition, we review i) the processes controlling Ra enrichment and depletion in coastal groundwater and seawater; ii) the systematics applied to estimate SGD using Ra isotopes and iii) we summarize additional applications of Ra isotopes in groundwater and marine studies. We also provide some considerations that will help refine SGD estimates and identify the critical knowledge gaps and research needs related to the current use of Ra isotopes as SGD tracers.

This article is a short introduction to the Plant theory. It describes the application of the theory with the use of the Remedy code. The Remedy code is a short code of seven digits or numbers that describe the position and classification of each plant. It is a kind of short Materia Medica. The first digit stands for the kingdom, which is 3 in the case of the Plant kingdom. The next three digits stand for series as known from the Element theory. The next two digits, digits 5 and 6, stand for Phases. Phases are similar to the Stages of the Element theory. The difference is that there are 8 Phases, in contrast to the 18 Stages. The Phases are linked to the eight columns of the Carbon series and Silicon series of the Periodic system. The last digit, digit 7, stands for the Stage as known from the Element theory.

The availability of the micronutrient iron (Fe) in surface waters determines primary production, N2 fixation, and microbial community structure in large parts of the world's ocean, and thus it plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling systems and the connected oxygen minimum zones (OMZs) are typically associated with elevated concentrations of redox-sensitive trace metals (e.g., Fe, manganese (Mn), and cobalt (Co)), with shelf sediments typically forming a key source. Over the last 5 decades, an expansion and intensification of OMZs has been observed and this trend is likely to proceed. However, it is unclear how trace-metal (TM) distributions and transport are influenced by decreasing oxygen (O2) concentrations. Here we present dissolved (d; 0.2 µm) TM data collected at seven stations along a 50 km transect in the Mauritanian shelf region. We observed enhanced concentrations of Fe, Co, and Mn corresponding with low O2 concentrations (

To analyze plutonium (Pu) in open ocean waters can be challenging due to the low seawater concentrations. In this study we compared two techniques for Pu determination, one in-situ MnO2 cartridge system and the more commonly used MnO2 precipitation technique. During the pre-pilot GEOTRACES cruise ANT XXX-1 (2005) we tested MnO2 cartridges for the pre-concentration of Pu from seawater at 19 sampling stations on a transect in the southeastern Atlantic Ocean between Vigo (Spain) and Cape Town (South Africa). Our in-situ sampling setup consisted of one particle cartridge followed by three MnO2 cartridges in a series. Through the system we pumped between 956 and 2700 I of surface seawater with a flow rate between 1.6 and 5.21/min. We found that the adsorption efficiency of a single MnO2 cartridge to adsorb Pu was rather constant and on average a 58 +/- 7%. The adsorption efficiency was also found to be independent of seawater: temperature in the range of 18.3-29.2 degrees C, salinity range 34.2-37.1 parts per thousand, and conductivity in the range of 46.8-58.4 mS/cm. In parallel with the in-situ sampling, discrete surface water samples between 259 and 281 I were taken and Pu was pre-concentrated using the MnO2 precipitation method. We find a good agreement between the Pu concentrations determined with the two different techniques. The in-situ pre-concentration technique requires more radiochemical work in the laboratory but has the advantage that large seawater volumes can be sampled without the necessity for radiochemical processing on-board the ship. The much larger volumes sampled with the in-situ technique compared with the precipitation technique, enables accurate determination of Pu-isotopic ratios with a low relative standard deviation. We have shown in this study that in-situ MnO2 cartridge technique can be used in a reliable way for the determination of dissolved Pu seawater concentration in open ocean waters.

Investigations in hydrology and hydrogeology are often hampered by a lack of parameters that permit direct observation or monitoring of the processes of interest [...]

The eutrophic Lake Eichbaumsee, a ~1 km long and 280 m wide (maximum water depth 16 m) dredging lake southeast of Hamburg (Germany), has been treated for water quality improvements using various techniques (i.e., aeration plants, removal of dissolved phosphorous by aluminum phosphorous precipitation, and by Bentophos® (Phoslock Environmental Technologies, Sydney, Australia), adsorption) during the past ~15 years. Despite these treatments, no long-term improvement of the water quality has been observed and the lake water phosphorous content has continued to increase by e.g., ~670 kg phosphorous between autumn 2014 and autumn 2019. As no creeks or rivers drain into the lake and hydrological groundwater models do not suggest any major groundwater discharge into the lake, sources of phosphorous (and other nutrients) are unknown. We investigated the phosphorous fluxes from sediment pore water and from groundwater in the water body of the lake. Sediment pore water was extracted from sediment cores recovered by divers in August 2018 and February 2019. Diffusive phosphorous fluxes from pore water were calculated based on phosphorus gradients. Stable water isotopes (δ2H, δ18O) were measured in the lake water, in interstitial waters in the banks surrounding the lake, in the Elbe River, and in three groundwater wells close to the lake. Stable isotope (δ2H, δ18O) water mass balance models were used to compute water inflow/outflow to/from the lake. Our results revealed pore-water borne phosphorous fluxes between 0.2 mg/m2/d and 1.9 mg/m2/d. Assuming that the measured phosphorous fluxes are temporarily and spatially representative for the whole lake, about 11 kg/a to 110 kg/a of phosphorous is released from sediments. This amount is lower than the observed lake water phosphorous increase of ~344 kg between April 2018 and November 2018. Water stable isotope (δ2H, δ18O) compositions indicate a water exchange between an aquifer and the lake water. Based on stable isotope mass balances we estimated an inflow of phosphorous from the aquifer to the lake of between ~150 kg/a and ~390 kg/a. This result suggests that groundwater-borne phosphorous is a significant phosphorous source for the Eichbaumsee and highlights the importance of groundwater for lake water phosphorous balances.

This article is a summary of ‘Introduction to the Plant Theory’ published in LINKS 2/2017. It describes the application of the theory with the use of the Remedy code.

To analyze plutonium (Pu) in open ocean waters can be challenging due to the low seawater concentrations. In this study we compared two techniques for Pu determination, one in-situ MnO

Submarine groundwater discharge (SGD) has been implicated as a significant source of nutrients and other potentially harmful substances to coastal sea. Although the number of reported SGD sites has increased recently, their stratigraphical architecture and aquifer geometry are rarely investigated in detail. This study analyses a multifaceted dataset of offshore seismic sub-bottom profiles, multibeam and sidescan sonar images of the seafloor, radon measurements of seawater and groundwater, and onshore ground-penetrating radar and refraction seismic profiles in order to reconstruct the detailed stratigraphical architecture of a high-latitude SGD site, which is connected to the Late-Pleistocene First Salpausselkä ice-marginal formation on the Hanko Peninsula in Finland. The studied location is characterized by a sandy beach, a sandy shore platform that extends 100–250 m seaward sloping gently to ca. 4 m water depth, and a steep slope to ca. 17 m water depth within ca. 50 m distance. The onshore radar and offshore seismic profiles are correlated based on unconformities, following the allostratigraphical approach. The aquifer is hosted in the distal sand-dominated part of an ice-contact subaqueous fan foreset. It is interpreted that gravel and coarse sand interbeds and lenses in the distal foreset, and, potentially, coarse couplet layers in the overlying glaciolacustrine rhythmite, provide conduits for localized groundwater flow. The SGD takes place predominantly through pockmarks on the seafloor, which are documented on the shore platform slope by multibeam and sidescan sonar images. Elevated radon-222 activity concentrations measured 1 m above seafloor confirm SGD from two pockmarks with fine sand surface sediment, whereas there was no discharge from a third pockmark that was covered with a thin organic-rich mud layer. The thorough understanding of the local stratigraphy and the geometry and composition of the aquifer that have been acquired in this study are crucial for successful hydrogeological modeling and flux studies at the SGD site.