The Importance of Kinetics and Redox in the Biogeochemical Cycling of Iron in the Surface Ocean

It is now well established that Iron (Fe) is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium conditions. Using this equilibrium approach, researchers have been able to detect and quantify organic complexing ligands in seawater and examine their role in increasing the overall solubility of iron. Our current knowledge about iron bioavailability to phytoplankton and bacteria is also based heavily on carefully controlled laboratory studies where it is assumed the chemical species are in equilibrium in line with the free ion association model and/or its successor the biotic ligand model. Similarly most field work on iron biogeochemistry generally consists of a single profile which is in essence a “snap-shot” in time of the system under investigation. However it is well known that the surface ocean is an extremely dynamic environment and it is unlikely if thermodynamic equilibrium between all the iron species present is ever truly achieved. In sunlit waters this is mostly due to the daily passage of the sun across the sky leading to photoredox processes which alter Fe speciation by cycling between redox states and between inorganic and organic species. Episodic deposition events, dry and wet, are also important perturbations to iron cycling as they bring in new iron to the system and alter the equilibrium between iron species and phases. Here we utilize new field data collected in the open ocean on the complexation kinetics of iron in the surface ocean to identify the important role of weak iron binding ligands (i.e., those that cannot maintain iron in solution indefinitely at seawater pH: αFeL < αFe′) in allowing transient increases in iron solubility in response to iron deposition events. Experiments with the thermal O2- source SOTS-1 also indicate the short term impact of this species on iron solubility also with relevance to the euphotic zone. This data highlights the roles of kinetics, redox, and weaker iron binding ligands in the biogeochemical cycling of iron in the ocean

Regeneration of Fe(II) during EIFeX and SOFeX

Investigations into Fe(II) cycling during two Southern Ocean mesoscale iron enrichment experiments, SOFeX and EIFeX, clearly show the importance of Fe(II) to iron speciation during these experiments. In both cases the added Fe(II) persisted significantly longer than its expected oxidation time indicating a significant Fe reduction process at work. During EIFeX diel studies showed a strong photochemically induced cycle in Fe(II) production in sunlit surface waters. Our results suggest that the photochemical cycling of iron may also be important in unfertilized waters of the Southern Ocean

Solubility of iron in the Southern Ocean

Iron solubility (cFeS) ranged from 0.4 to 1.5 nmol L−1, decreasing from south to north in three different Southern Ocean zones (the Coastal Zone, the Antarctic Zone, and the Polar Frontal Zone plus the Subantarctic Zone). This decrease was at times correlated with an increase in temperature. Organic Fe solubility (cFeS,org), which was obtained by subtracting from total measured Fe solubility the solubility of inorganic species of iron (Fe) at the measurement temperature (20°C), ranged from 0.3 to 1.3 nmol L−1, representing an average of 32 ± 14% of the concentration of ligands in the dissolved size fraction as determined via competitive ligand exchange–absorptive cathodic stripping voltammetry (barring a handful of extremely high values from a transect run to the east of Prydz Bay). Values of cFeS were mainly lower than the predicted value for inorganic Fe solubility at the in situ temperature. Total in situ Fe solubility (cFeS,adj) was therefore estimated by adjusting for inorganic Fe solubility at in situ temperatures (between −2°C and +18°C). Because in situ temperatures in the Antarctic Circumpolar Current were mostly lower than +3°C, such cFeS,adj values, ranging from 0.5 to 1.8 nmol L−1, were roughly twice as large as cFeS,org. The adjustment relies heavily on model calculations of inorganic Fe solubility but, if correct, indicates that the bulk of the solubility of Fe in the cold waters of the Southern Ocean is tied to the solubility of inorganic Fe rather than to Fe ligands in the soluble size fraction

Is the homophone advantage influenced by post-lexical effects?

No Abstract availabl

Co-production of research derived actionable resources for the delivery of individual service funds (EQUALD study): protocol

Adults with a learning disability who receive social care are legally entitled to a personal budget. Personal budgets were introduced to promote choice and control in support. Individual Service Funds were introduced as a flexible way that personal budgets can be managed by a provider while maintaining choice and control for the individual. Individual Service Funds have been shown to improve quality of life for individuals and efficiency in support. Despite this, only 20% of local authorities offer them to adults with a learning disability, demonstrating the need for resources to be developed to support their delivery. This protocol described a co-production study with key stakeholders to develop and refine Individual Service Fund resources. Our primary aim is to co-produce two actionable resources: to support development, delivery, consistency, and sustained provision of ISFs; and to support uptake and optimal use of ISFs by recipients. We also aim to user-test and evaluate these resources with three Local Authorities. The result of this study will be two resources that will support the uptake of Individual Service Funds for adults with a learning disability that will be freely available online

Guidance for reporting intervention development studies in health research (GUIDED) : an evidence-based consensus study

Objective: To improve the quality and consistency of intervention development reporting in health research. Design: This was a consensus exercise consisting of two simultaneous and identical three-round e-Delphi studies (one with experts in intervention development and one with wider stakeholders including funders, journal editors and public involvement members), followed by a consensus workshop. Delphi items were systematically derived from two preceding systematic reviews and a qualitative interview study. Participants: Intervention developers (n=26) and wider stakeholders (n=18) from the UK, North America and Europe participated in separate e-Delphi studies. Intervention developers (n=13) and wider stakeholders (n=13) participated in a 1-day consensus workshop. Results: e-Delphi participants achieved consensus on 15 reporting items. Following feedback from the consensus meeting, the final inclusion and wording of 14 items with description and explanations for each item were agreed. Items focus on context, purpose, target population, approaches, evidence, theory, guiding principles, stakeholder contribution, changes in content or format during the development process, required changes for subgroups, continuing uncertainties, and open access publication. They form the GUIDED (GUIDance for the rEporting of intervention Development) checklist, which contains a description and explanation of each item, alongside examples of good reporting. Conclusions: Consensus-based reporting guidance for intervention development in health research is now available for publishers and researchers to use. GUIDED has the potential to lead to greater transparency, and enhance quality and improve learning about intervention development research and practice

Self-completed online dietary recalls as an alternative method of dietary assessment for dietetic outpatient appointments: A feasibility study

Background Integrating digital dietary assessment within dietetic care could save time and reduce costs, at the same time as increasing patient engagement. The present study explores the feasibility of implementing a web-based dietary assessment tool, myfood24 (https://www.myfood24.org), into routine healthcare. Methods This mixed methods feasibility study recruited dietitians and patients from a National Health Service (NHS) hospital outpatient setting. Patients completed and shared three online 24-h dietary recalls in advance, which were used as a dietary assessment by dietitians. Recruitment data were collected and questionnaires on technology, usability, and acceptability were completed. Patient interviews and focus groups with dietitians were conducted. Results Eleven dietitians working in allergy, bariatrics, diabetes, oncology, general, renal, infectious diseases, and coeliac services took part with 39 patients. Recruitment rates were highest in bariatrics and lowest in renal and oncology. Compared to other studies, completion rates were good, with 29 (74.4%) completing three recalls despite lower technology readiness and software usability scores than in similar studies. Illness and difficulty with technology were reasons for non-completion. Opportunity to receive nutritional feedback from the tool and share this with a dietitian motivated patients to complete the record accurately. Consultation times were shortened in approximately one-third of appointments and a higher proportion of time was spent on nutritional education compared to usual practice. However, mean preparation time increased by 13 min per appointment because dietitians found nutritional analysis reports difficult to interpret. Conclusions It is feasible to introduce a digital dietary assessment tool into NHS dietetic practice. However, further development is needed to ensure that the tool is suitable for healthcare

A luminescent whole-cell cyanobacterial bioreporter for measuring Fe availability in diverse marine environments

A Synechococcus sp. strain PCC 7002 Fe bioreporter was constructed containing the isiAB promoter fused to the Vibrio harveyi luxAB genes. Bioreporter luminescence was characterized with respect to the free ferric ion concentration in trace metal-buffered synthetic medium. The applicability of the Fe bioreporter to assess Fe availability in the natural environment was tested by using samples collected from the Baltic Sea and from the high-nutrient, low-chlorophyll subarctic Pacific Ocean. Parallel assessment of dissolved Fe and bioreporter response confirmed that direct chemical measurements of dissolved Fe should not be considered alone when assessing Fe availability to phytoplankton