Intracellular nitrate of marine diatoms as a driver of anaerobic nitrogen cycling in sinking aggregates

Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations > 60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2-3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations

Measuring regional business resilience

The concept of regional resilience is explored by understanding the resilience of individual firms within both the region (and their capabilities to cope, adapt and reconfigure) and a constantly evolving economic environment. This study examines the utility of the QuiScore credit indicator (from the Financial Analysis Made Easy (FAME) database) to measure both firm and regional economic resilience. Using the Cardiff Capital Region in Wales, UK (for the period 2006–16) as a case study, the results indicate that the QuiScore is an effective indicator of the economic resilience of firms as well as an early warning indicator of economic stresses for a region

Protocols for Assessing Transformation Rates of Nitrous Oxide in the Water Column

Nitrous oxide (N2O) is a potent greenhouse gas and an ozone destroying substance. Yet, clear step-by-step protocols to measure N2O transformation rates in freshwater and marine environments are still lacking, challenging inter-comparability efforts. Here we present detailed protocols currently used by leading experts in the field to measure water-column N2O production and consumption rates in both marine and other aquatic environments. We present example 15N-tracer incubation experiments in marine environments as well as templates to calculate both N2O production and consumption rates. We discuss important considerations and recommendations regarding (1) precautions to prevent oxygen (O2) contamination during low-oxygen and anoxic incubations, (2) preferred bottles and stoppers, (3) procedures for 15N-tracer addition, and (4) the choice of a fixative. We finally discuss data reporting and archiving. We expect these protocols will make 15N-labeled N2O transformation rate measurements more accessible to the wider community and facilitate future inter-comparison between different laboratories

DETI Inspire Engagement Report 2020-2021

From September 2020 to December 2021, DETI Inspire has delivered an impressive array of outputs and engagement activities. In two years, the team have directly engaged 6,832 children and 216 teachers from 73 schools and community groups in the West of England, with an estimated 97,550 children reached altogether through dissemination efforts. Along the way, children have been able to have conversations with real-life engineers through (online) Q&A sessions, card games and skill shares. 455 engineers have so far shared their experiences, as well as at least 17 industry partners and three charities.42% of total direct engagements (N=3,415) came directly through in-person BoxED sessions, all four developed and launched by DETI Inspire in 2021: The West in Minecraft (N=2,047, 60%), Engineering Curiosity (N=357, 10%), WeCount (N=319, 9%), and We Make Our Future (N=692, 20%). 42% (10) of all the schools engaged in BoxED sessions (total = 24) came from areas within the most deprived 20% of the country, and 17% (4) came from the most deprived 30%.The last 20 months has seen the programme: pair female junior engineers with senior female mentors (page 13); establish a network of 102 engineers from diverse backgrounds (page 13); distribute 132 Engineering Curiosity card packs to schools and community groups and launch 40 Tik-Tok videos to accompany them (p 16); host a Sustainable Solutions Summit to 16-18-year-olds (page 26); champion sustainable engineering at COP26 (page 28); beam in engineers to 3,500 children during the height of the pandemic (p39); and reach over 250,000 people through social media (p 35). For a full list of highlights, and for details of DETI Inspire’s engagements, see Table 1.Despite another year of uncertainty, with rules around in-person events frequently changing, the DETI Inspire programme has excelled under the circumstances. Adapting to the changing rules and guidance, the team managed to engage in-person when they could – enriching children and young people’s cultural experiences, limited by the pandemic – and offer well attended online events when they could not. For instance, from two online events alone, DETI Inspire reached 9,000 children and young people.DETI Inspire will continue to deliver BoxED activities to schools across the West of England Combined Authority (WECA), with a full calendar of bookings right up until June. The programme will also support this year’s Leaders Award (p 42), Great Science Share (p51), and take part in the long-awaited return of Bristol’s Storytale Festival (p 511), among other activities. DETI Inspire is excelling in promoting engineering for sustainability among children, young people and adults from diverse backgrounds, not only in WECA, but also nationally and across Europe

Small sinking particles control anammox rates in the Peruvian oxygen minimum zone

Anaerobic oxidation of ammonium (anammox) in oxygen minimum zones (OMZs) is a major pathway of oceanic nitrogen loss. Ammonium released from sinking particles has been suggested to fuel this process. During cruises to the Peruvian OMZ in April–June 2017 we found that anammox rates are strongly correlated with the volume of small particles (128–512 µm), even though anammox bacteria were not directly associated with particles. This suggests that the relationship between anammox rates and particles is related to the ammonium released from particles by remineralization. To investigate this, ammonium release from particles was modelled and theoretical encounters of free-living anammox bacteria with ammonium in the particle boundary layer were calculated. These results indicated that small sinking particles could be responsible for ~75% of ammonium release in anoxic waters and that free-living anammox bacteria frequently encounter ammonium in the vicinity of smaller particles. This indicates a so far underestimated role of abundant, slow-sinking small particles in controlling oceanic nutrient budgets, and furthermore implies that observations of the volume of small particles could be used to estimate N-loss across large areas

An exploratory study of the resilience of manufacturing in the Cardiff Capital Region

Sustainability in all its guises is important for the long term continuance of manufacturing. The ideas of local sustainability and resilience have become increasing popular topics for study. The drive for economic resilience is causing governments to look at regional strategies to improve economic sustainability and resilience. A recent example of this is the establishment of a Cardiff Capital Region (CCR) in Wales. This exploratory study takes an initial look at the resilience of manufacturing in the CCR vis-à-vis economic resilience using the FAME dataset and QuiScore measure. Results indicate that on the whole manufacturing looks broadly healthy. However, some potential areas of concern were identified, many of the biggest and healthiest companies are not headquartered in the CCR, whereas 98 % of the weakest companies are, and there are inter and intra sectorial differences. The study also suggests that measures such as QuiScore should perhaps not be used in isolation as its methodology is unknown and a large number of companies do not have QuiScores

Enhanced Nitrogen Loss by Eddy-Induced Vertical Transport in the Offshore Peruvian Oxygen Minimum Zone

The eastern tropical South Pacific (ETSP) upwelling region is one of the ocean’s largest sinks of fixed nitrogen, which is lost as N2 via the anaerobic processes of anammox and denitrification. One-third of nitrogen loss occurs in productive shelf waters stimulated by organic matter export as a result of eastern boundary upwelling. Offshore, nitrogen loss rates are lower, but due to its sheer size this area accounts for ~70% of ETSP nitrogen loss. How nitrogen loss and primary production are regulated in the offshore ETSP region where coastal upwelling is less influential remains unclear. Mesoscale eddies, ubiquitous in the ETSP region, have been suggested to enhance vertical nutrient transport and thereby regulate primary productivity and hence organic matter export. Here, we investigated the impact of mesoscale eddies on anammox and denitrification activity using 15N-labelled in situ incubation experiments. Anammox was shown to be the dominant nitrogen loss process, but varied across the eddy, whereas denitrification was below detection at all stations. Anammox rates at the eddy periphery were greater than at the center. Similarly, depth-integrated chlorophyll paralleled anammox activity, increasing at the periphery relative to the eddy center; suggestive of enhanced organic matter export along the periphery supporting nitrogen loss. This can be attributed to enhanced vertical nutrient transport caused by an eddy-driven submesoscale mechanism operating at the eddy periphery. In the ETSP region, the widespread distribution of eddies and the large heterogeneity observed in anammox rates from a compilation of stations suggests that eddy-driven vertical nutrient transport may regulate offshore primary production and thereby nitrogen loss

Compositional control of pore geometry in multivariate metal-organic frameworks: an experimental and computational study

A new approach is reported for tailoring the pore geometry in five series of multivariate metal-organic frameworks (MOFs) based on the structure [Zn-2(bdc)(2)(dabco)] (bdc = 1,4-benzenedicarboxylate, dabco = 1,8-diazabicyclooctane), DMOF-1. A doping procedure has been adopted to form series of MOFs containing varying linker ratios. The series under investigation are [Zn-2(bdc)(2-x)(bdc-Br)(x)(dabco)]center dot nDMF 1 (bdc-Br = 2-bromo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-I)(x)(dabco)]center dot nDMF 2 (bdc-I = 2-iodo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NO2)(x)(dabco)]center dot nDMF 3 (bdc-NO2 = 2-nitro-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NH2)(x)(dabco)]center dot nDMF 4 (bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) and [Zn-2(bdc-Br)(2-x)(bdc-I)(x)(dabco)] nDMF 5. Series 1-3 demonstrate a functionality-dependent pore geometry transition from the square, open pores of DMOF-1 to rhomboidal, narrow pores with increasing proportion of the 2-substituted bdc linker, with the rhomboidal-pore MOFs also showing a temperature-dependent phase change. In contrast, all members of series 4 and 5 have uniform pore geometries. In series 4 this is a square pore topology, whilst series 5 exhibits the rhomboidal pore form. Computational analyses reveal that the pore size and shape in systems 1 and 2 is altered through non-covalent interactions between the organic linkers within the framework, and that this can be controlled by the ligand functionality and ratio. This approach affords the potential to tailor pore geometry and shape within MOFs through judicious choice of ligand ratios

Trace Metal Chemistry in the Water Column of the Angola Basin - A Contribution to the International GEOTRACES Program - Cruise No. M121, November 22, – December 27, 2015, Walvis Bay (Namibia) – Walvis Bay (Namibia)

Meteor Cruise M121 was dedicated to the investigation of the distribution of dissolved and particulate trace metals and their isotopic compositions (TEIs) in the full water column of the Angola Basin and the northernmost Cape Basin. A key aim was to determine the driving factors for the observed distributions, which includes the main external inputs, as well as internal cycling and ocean circulation. The research program of the cruise is official part of the international GEOTRACES program (www.geotraces.org) and cruise M121 corresponds to GEOTRACES cruise GA11. Subject of the cruise was the trace metal clean and contamination-free sampling of waters and particulates for subsequent analyses of the TEIs in the home laboratories of the national and international participants. Besides a standard rosette for the less contaminant prone metals, trace metal clean sampling was realized by using for the first time a new dedicated, coated trace metal clean rosette equipped with Teflon-coated GO-FLO bottles operated via a plastic coated cable from a mobile winch of GEOMAR Kiel. The particulate samples were collected under trace metal clean conditions using established in-situ pump systems operated from Meteor’s Aramid line. The cruise track led from Walvis Bay northwards along the West African margin until 3°S, then turned west until the Zero Meridian, which was followed southwards until 30°S. Then the cruise track turned east again until the Namibian margin was reached and then completed the near shore track northwards until Walvis Bay. The track crossed areas of major external inputs including dust from the Namib Desert and exchange with the west African continental margin and with the oxygen depleted shelf sediments of the Benguela upwelling, as well as with the plume of the Congo outflow, that was followed from its mouth northwards. Our investigations of internal cycling included the extremely high productivity associated with the Benguela Upwelling and the elevated productivity of the Congo plume contrasting with the extremely oligotrophic waters of the southeastern Atlantic Gyre. The links between TEI biogeochemistry and the nitrogen cycle forms an important aspect of our study. The major water masses contributing the Atlantic Meridional Overturning Circulation were sampled in order to investigate if particular TEI signatures are suitable as water mass tracers, in particular near the ocean margin and in the restricted deep Angola Basin. A total of 51 full water column stations were sampled for the different dissolved TEIs, which were in most cases accompanied by sampling for particulates and radium isotopes using the in-situ pumps. In addition, surface waters were continuously sampled under trace metal clean conditions using a towed fish and aerosol and rain samples were continuously collected