The organic ties of iron:Or the origin and fate of Fe-binding organic ligands

Primary production in the oceans depends on, among other nutrients, the presence of iron in the seawater. Iron does not dissolve well in seawater and needs to be bound by a soluble substance to be bioavailable: iron-binding organic ligands. These ligands are a diverse mix of organic substances and relative contributors are understudied. This dissertation aims to gain insight in sources of iron-binding organic ligands and to study the effect of microbial processes through seaborne and laboratory study.We find that in the Mediterranean Sea sources of these ligands are diverse, and sometimes different from the sources of iron. In the Arctic Ocean, iron and organic material from surrounding rivers is transported across the surface. Among which humic substances, bacterial breakdown products known to bind iron, which are an important part of the ligand pool here. This transport is expected to be highly sensitive to climate change which changes the discharge of organic material in river catchments.In laboratory study we find that viral infection of phytoplankton is hampered by low iron concentrations, limiting the effectiveness of nutrient cycling through the viral breakup, or lysis, of phytoplankton cells. We also show that viral lysis increases the concentration of ligands, dependent on the phytoplankton host species. Bacteria are found to modify parts of the ligand pool, and pose a possible loss factor of ligands.Finally, we identify important considerations for methodology, as no approach currently applied is capable of elucidating the composition of the iron-binding organic ligand pool alone

The organic ties of iron:Or the origin and fate of Fe-binding organic ligands

Primary production in the oceans depends on, among other nutrients, the presence of iron in the seawater. Iron does not dissolve well in seawater and needs to be bound by a soluble substance to be bioavailable: iron-binding organic ligands. These ligands are a diverse mix of organic substances and relative contributors are understudied. This dissertation aims to gain insight in sources of iron-binding organic ligands and to study the effect of microbial processes through seaborne and laboratory study.We find that in the Mediterranean Sea sources of these ligands are diverse, and sometimes different from the sources of iron. In the Arctic Ocean, iron and organic material from surrounding rivers is transported across the surface. Among which humic substances, bacterial breakdown products known to bind iron, which are an important part of the ligand pool here. This transport is expected to be highly sensitive to climate change which changes the discharge of organic material in river catchments.In laboratory study we find that viral infection of phytoplankton is hampered by low iron concentrations, limiting the effectiveness of nutrient cycling through the viral breakup, or lysis, of phytoplankton cells. We also show that viral lysis increases the concentration of ligands, dependent on the phytoplankton host species. Bacteria are found to modify parts of the ligand pool, and pose a possible loss factor of ligands.Finally, we identify important considerations for methodology, as no approach currently applied is capable of elucidating the composition of the iron-binding organic ligand pool alone

The organic ties of iron:Or the origin and fate of Fe-binding organic ligands

Primary production in the oceans depends on, among other nutrients, the presence of iron in the seawater. Iron does not dissolve well in seawater and needs to be bound by a soluble substance to be bioavailable: iron-binding organic ligands. These ligands are a diverse mix of organic substances and relative contributors are understudied. This dissertation aims to gain insight in sources of iron-binding organic ligands and to study the effect of microbial processes through seaborne and laboratory study. We find that in the Mediterranean Sea sources of these ligands are diverse, and sometimes different from the sources of iron. In the Arctic Ocean, iron and organic material from surrounding rivers is transported across the surface. Among which humic substances, bacterial breakdown products known to bind iron, which are an important part of the ligand pool here. This transport is expected to be highly sensitive to climate change which changes the discharge of organic material in river catchments.In laboratory study we find that viral infection of phytoplankton is hampered by low iron concentrations, limiting the effectiveness of nutrient cycling through the viral breakup, or lysis, of phytoplankton cells. We also show that viral lysis increases the concentration of ligands, dependent on the phytoplankton host species. Bacteria are found to modify parts of the ligand pool, and pose a possible loss factor of ligands. Finally, we identify important considerations for methodology, as no approach currently applied is capable of elucidating the composition of the iron-binding organic ligand pool alone

Terms of debate: consensus definitions to guide the scientific discourse on visual distraction

Hypothesis-driven research rests on clearly articulated scientific theories. The building blocks for communicating these theories are scientific terms. Obviously, communication – and thus, scientific progress – is hampered if the meaning of these terms varies idiosyncratically across (sub)fields and even across individual researchers within the same subfield. We have formed an international group of experts representing various theoretical stances with the goal to homogenize the use of the terms that are most relevant to fundamental research on visual distraction in visual search. Our discussions revealed striking heterogeneity and we had to invest much time and effort to increase our mutual understanding of each other’s use of central terms, which turned out to be strongly related to our respective theoretical positions. We present the outcomes of these discussions in a glossary and provide some context in several essays. Specifically, we explicate how central terms are used in the distraction literature and consensually sharpen their definitions in order to enable communication across theoretical standpoints. Where applicable, we also explain how the respective constructs can be measured. We believe that this novel type of adversarial collaboration can serve as a model for other fields of psychological research that strive to build a solid groundwork for theorizing and communicating by establishing a common language. For the field of visual distraction, the present paper should facilitate communication across theoretical standpoints and may serve as an introduction and reference text for newcomers

The prevalence of metabolic syndrome and metabolically healthy obesity in Europe: a collaborative analysis of ten large cohort studies

Peer reviewe

Phytoplankton virus production negatively affected by iron limitation

Fe-limited monocultures of the ubiquitous algae Micromonas pusilla and Phaeocystis globosa were infected with their respective viruses (MpV and PgV) to ascertain the effect of Fe-limitation on phytoplankton host-virus dynamics. The effect of the viral shunt on Fe concentrations and bioavailability is starting to gain attention, since not only is Fe released through lysis, but also its solubility is increased by the simultaneous release of Fe-binding dissolved organic ligands. However, the effect of Fe-limitation on the process of viral lysis itself is poorly understood. In this study fine adjustment of a seawater-based culture medium including the use of ultra-clean trace metal conditions and protocols allowed for Fe-limited growth at nanomolar amounts as opposed to micromolar amounts typically employed in culturing. Viral lysates derived from Fe-limited and Fe-replete (for comparison) hosts were cross-inoculated in hosts of both Fe treatments, to judge the quality of the resulting lysate as well as the effect of Fe introduction after initial infection. For both phytoplankton host-virus systems, the virus burst size reduced strongly under Fe stress, i.e. on average 28 ±1% of replete. Moreover, the MpV virus progeny showed highly reduced infectivity of 30±7%, whereas PgV infectivity was not affected. A small addition of Fe to Fe-limited cultures coming from the Fe-replete lysate counteracted the negative effect of Fe-limitation on phytoplankton virus production to some extent (but still half of replete), implying that the physiological history of the host at the moment of infection was an important underlying factor. These results indicate that Fe-limitation has the strong potential to reduce the loss of phytoplankton due to virus infection, thereby affecting the extent of Fe-cycling through the viral shunt. To what extent this affects the contribution of viral lysis-induced organic ligand release needs further study

Elements for a National Master Plan for CCS — Lessons learnt

AbstractThis paper describes the elements for a Dutch CCS Master Plan and will give concrete recommendations for countries wishing to devise a national CCS strategy based on the insights learnt from the Dutch experience. It analyzes which elements of a Master Plan are crucial and discusses the main findings from the Dutch study.The main element of the Dutch Master plan was the “fields strategy” in which the storage potential of The Netherlands was matched with CO2 emissions over time. This culminated in a strategy consisting of two possible routes for the two most important CCS regions in The Netherlands. It also showed that if both onshore and offshore storage potential is available, all projected emissions can be accommodated until 2050. Furthermore, the interviews with stakeholders gave very useful insights into the drivers for companies to participate in CCS as well as potential show stoppers. Lastly, the study into the costs of converting offshore oil and gas production platform for re-use as CO2 injection platforms shed light on the cost-effective use of infrastructure and gave an indication on the effects of “mothballing” oil and gas production platforms on the costs of CO2 injection

Dissolved iron measured on board with Flow injection analysis and iron-binding dissolved organic ligands from Ultra Clean CTD collected depth profiles during GEOTRACES PS94 Arctic cruise on Polarstern

Data from Polarstern cruise PS94 in the Arctic in 2015 with chief scientist Ursula Schauer. In order to explain geochemical cycles of Fe in the ocean, M. Rijkenberg, L. Gerringa and H. Slagter a.o. sampled filtered seawater using an ultra clean titanium CTD. In these samples on board measurements were executed: dissolved Fe by flow injection analysis and the characteristics of the dissolved organic Fe-binding organic ligands (totalL); characteristics being the concentration of these ligands and the conditional binding constant of the Fe-complex (K' expressed as its logarithm: logK). Moreover in order to relate the dissolved organic Fe-binding organic ligands to humic substances, fluorescence of dissolved organic matter was measured as well as humic substances using voltammetry