Janet G. Hering

The ScienceInsider piece “Max Planck director loses post after probe of misconduct” (A. Curry, 5 November, p. 671) is the latest in a series of reports of dismissals, demotions, and conflicts involving prominent women in academic research. This story and previous reports have highlighted leadership issues and bullying by women not only at the Max Planck Institute (1) but also in top academic positions at ETH Zurich (2) and the University of London (3). We urge caution in reporting such stories given that women face more obstacles to attaining leadership positions and are often held to a different standard than men when it comes to how their behavior is interpreted.

James (Jim) Morgan was a leading figure in the field of environmental science and engineering. He championed the application of chemistry in the study of the environment and the design and optimization of environmental treatment processes. Jim influenced the field through his classic text Aquatic Chemistry, coauthored with Werner Stumm, his role as founding editor of Environmental Science& Technology, his seminal contribution to computational methods for the calculation of chemical equilibria, and most especially, his mentorship of his extended academic family. Jim transmitted his enthusiasm for research, particularly on the chemistry of manganese and iron, so successfully to his doctoral students and postdoctoral advisees that many of them carried these topics forward in their own careers.

Dissolution of Fe(III)-phases is a key process in making iron available to biota and in the mobilization of associated trace elements. Recently we demonstrated that submicromolar concentrations of Fe(II) significantly accelerate rates of ligand-controlled dissolution of Fe(III) (hydr)oxides at circumneutral pH. Here, we extend this work by studying isotope exchange and dissolution with lepidocrocite (Lp) and goethite (Gt) in the presence of 20 µM or 50 µM DFOB. Experiments with Lp at pH 7 were conducted in carbonate buffered suspensions to mimic environmental conditions. We applied a simple empirical model to determine dissolution rates, and a more complex kinetic model that accounts for the observed isotope exchange and catalytic effect of Fe(II). The fate of added tracer ⁵⁷Fe(II) was strongly dependent on the order of addition of ⁵⁷Fe(II) and ligand. When DFOB was added first, tracer ⁵⁷Fe remained in solution. When ⁵⁷Fe(II) was added first, isotope exchange between surface and solution could be observed at pH 6.0 but not at pH 7.0 and 8.5 where ⁵⁷Fe(II) was almost completely adsorbed. During dissolution of Lp with DFOB, ratios of released ⁵⁶Fe and ⁵⁷Fe were largely independent of DFOB concentrations. In the absence of DFOB, addition of phenanthroline 30 min after tracer ⁵⁷Fe desorbed predominantly ⁵⁶Fe(II), indicating that electron transfer from adsorbed ⁵⁷Fe to ⁵⁶Fe of the Lp surface occurs on a time scale of minutes to hours. In contrast, comparable experiments with Gt desorbed predominantly ⁵⁷Fe(II), suggesting a longer timescale for electron transfer on the Gt surface. Our results show that addition of 1-5 µM Fe(II) leads to dynamic charge transfer between dissolved and adsorbed species and to isotope exchange at the surface, with the dissolution of Lp by ligands accelerated by up to 60-fold.

For such a simple substance, water plays a remarkable variety of critical roles at scales ranging from molecular to global. Water is essential to life, constituting roughly 60% of our bodies and is a dominant feature of our planet, covering over 70% of its surface. Because of the importance of water to society – for purposes ranging from consumption and sanitation to irrigation, navigation, and energy production – water management has been a principal responsibility of civil society throughout history. Water infrastructure represents a major investment on the part of society and has dramatically changed the extent and function of natural water bodies and watercourses. With the current megatrends of population growth, urbanization and changing consumption patterns (especially to more meat‐based diets), demands, and pressures on water resources are increasing. Meeting the direct needs of societies and, simultaneously, maintaining aquatic ecosystem structure and function will require collaboration, cooperation, and the open sharing of knowledge and experience among water researchers (from the natural, social, and engineering sciences), professionals (from the public and private sectors) engaged in management and regulation of water supply and resources and civil society organizations that seek to promote sustainable water management and protection of aquatic ecosystems.

Dissolution of iron(III)phases is a key process in soils, surface waters, and the ocean. Previous studies found that traces of Fe(II) can greatly increase ligand controlled dissolution rates at acidic pH, but the extent that this also occurs at circumneutral pH and what mechanisms are involved are not known. We addressed these questions with infrared spectroscopy and ⁵⁷Fe isotope exchange experiments with lepidocrocite (Lp) and 50 μM ethylenediaminetetraacetate (EDTA) at pH 6 and 7. Addition of 0.2–10 μM Fe(II) led to an acceleration of the dissolution rates by factors of 7–31. Similar effects were observed after irradiation with 365 nm UV light. The catalytic effect persisted under anoxic conditions, but decreased as soon as air or phenanthroline was introduced. Isotope exchange experiments showed that added ⁵⁷Fe remained in solution, or quickly reappeared in solution when EDTA was added after ⁵⁷Fe(II), suggesting that catalyzed dissolution occurred at or near the site of ⁵⁷Fe incorporation at the mineral surface. Infrared spectra indicated no change in the bulk, but changes in the spectra of adsorbed EDTA after addition of Fe(II) were observed. A kinetic model shows that the catalytic effect can be explained by electron transfer to surface Fe(III) sites and rapid detachment of Fe(III)EDTA due to the weaker bonds to reduced sites. We conclude that the catalytic effect of Fe(II) on dissolution of Fe(III)(hydr)oxides is likely important under circumneutral anoxic conditions and in sunlit environments.

For the last 12 years, I have had the pleasure and privilege to serve as the Director of the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and as a professor at the Swiss Federal Institutes of Technology (ETH) Zurich and Lausanne (EPFL). My affiliations have afforded me a rare opportunity to observe the structure and governance of academic institutions and to reflect on my own experience in institutional leadership. I have attempted to place my experience in the context of the literature on leadership, particularly that relating to women and academia. On the basis of my experience and reading, I make some recommendations for women faculty, for women in positions of institutional leadership in academia, and for academic institutions. I am deeply convinced that greater participation by women (and members of other under-represented groups) in institutional leadership is needed if academia is to make a meaningful contribution to addressing the huge challenges that face humanity.

Dissolution of Fe(III) (hydr)oxide minerals by siderophores (i.e. Fe-specific, biogenic ligands) is an important step in Fe acquisition in environments where Fe availability is low. The observed co-exudation of reductants and ligands has raised the question of how redox reactions might affect ligand-controlled (hydr)oxide dissolution and Fe acquisition. We examined this effect in batch dissolution experiments using two structurally distinct ligands (desferrioxamine B (DFOB) and N,N′-di(2-hydroxybenzyl)ethylene-diamine-N,N′-diacetic acid (HBED)) and four Fe(III) (hydr)oxide minerals (lepidocrocite, 2-line ferrihydrite, goethite and hematite) over an environmentally-relevant pH range (4 - 8.5). The experiments were conducted under anaerobic conditions with varying concentrations of (adsorbed) Fe(II) as the reductant. We observed a catalytic effect of Fe(II) on ligand-controlled dissolution even at sub-micromolar Fe(II) concentrations with up to a 13-fold increase in dissolution rate. The effect was larger for HBED than for DFOB. It was observed for all four Fe(III) (hydr)oxide minerals, but it was most pronounced for goethite in the presence of HBED. It was observed over the entire pH range with the largest effect at pH 7 and 8.5, where Fe deficiency typically occurs. The occurrence of this catalytic effect over a range of environmentally relevant conditions and at very low Fe(II) concentrations suggests that redox-catalysed, ligand-controlled dissolution may be significant in biological Fe acquisition and in redox transition zones.