Dissolved iron speciation from 2013 U.S. GEOTRACES Eastern Pacific Zonal Transect from R/V Thomas G. Thompson TN303 from October-December 2013 (U.S. GEOTRACES EPZT project, EPZT Fe Cu Co project)

Dataset: Dissolved iron speciation: EPZTThis dataset presents the concentrations and conditional stability constants of dissolved iron-binding organic ligands determined in full water column samples collected on the US GEOTRACES East Pacific Zonal Transect (GEOTRACES cruise GP16). Dissolved iron concentrations used to calculate the organic complexation parameters are also included in this dataset for reference. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/668556NSF Division of Ocean Sciences (NSF OCE) OCE-144196

Indiana Nonprofit Employment: Historical Trends in Arts, Entertainment and Recreation, 1995-2009

Nonprofit organizations make significant contributions to the quality of life for the residents of Indiana. In particular, arts, entertainment, and recreation organizations play an important role in preserving culture, enriching the lives of children and adults, fostering creative expression, and providing sport and entertainment. These organizations may also serve as a powerful economic force for the state by attracting not only tourists, but also a young, educated workforce that can have a major positive impact on regional output and productivity. This report from the Indiana Nonprofits: Scope and Community Dimensions project presents new data on the size, composition, and distribution of paid arts, entertainment, and recreation employment in Indiana's private nonprofit sector over the 1995-2009 time period. All dollars are adjusted for inflation and are reported in constant 2009 dollars. Note that there are too few government employees in the arts, entertainment and recreation industry to allow for separate analysis of public sector employment

Defining the Environmental Niche of the Two Main Clades of \u3ci\u3eTrichodesmium\u3c/i\u3e: A Study on the West Florida Shelf

Dinitrogen (N2) fixation is the process of taking widely abundant but mostly biologically inaccessible N2 gas and converting it into more biologically accessible forms of the essential macronutrient nitrogen. Only a small fraction of organisms known as diazotrophs can perform biological N2 fixation. Trichodesmium is one such genus of N2-fixing marine cyanobacteria that is commonly observed in waters along the West Florida Shelf (WFS). We hypothesize that the two main Trichodesmium clades (T. erythraeum and T. thiebautii) occupy distinct environmental niches, one being more coastal and one being more oceanic. To test this hypothesis, we quantified gene abundance of both clades and compared the results with hydrographic data to distinguish any trends in niche distribution in samples collected on the WFS from three separate cruises. T. thiebautii abundance was higher further from the coast (at stations with greater bottom depths) and the T. erythraeum abundance was higher closer to the coast (at stations with lower bottom depths). A lack of nearshore sampling in 2015 initially made it difficult to conclusively identify trends in niche distribution, however with the addition of 2018 and 2019 samples, we observed a consistent coastal vs. open ocean niche separation for the two clades. In addition, T.thiebautii abundance was also significantly positively correlated with salinity. While previous work has found T. thiebautii is more abundant than T. erythraeum in open ocean surface waters, this is the first study to examine Trichodesmium clade abundance in a near-shore environment.https://digitalcommons.odu.edu/gradposters2021_sciences/1010/thumbnail.jp

Dissolved trace metal concentrations from depth profiles during RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean from 2016-09-11 to 2016-10-10

Dataset: NBP1608 TMs: stationsDissolved trace metal concentrations from depth profiles during RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean from 2016-09-11 to 2016-10-10. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/781773NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-14436462020-06-0

Dust Deposition to the Bermuda Region: A Comparison of Estimates Using Seasonally-resolved Measurements of Aluminum in Water-column, Aerosol, and Rain Samples

Dust deposition is a major source of bioactive trace elements to the surface ocean, yet this flux remains difficult to constrain. Previously, time-averaged dust flux has been estimated using surface ocean dissolved aluminum (DAl) concentrations, assumed values for aerosol aluminum solubility (%AlS), and the residence time of DAl in the surface mixed layer (SML). We apply this method to estimate dust deposition in the Bermuda Atlantic Time-series Study (BATS) region using water-column DAl data from cruises in 2019, which is compared with direct flux estimates from contemporaneous measurements of aluminum in aerosols and rain collected on Bermuda. Seasonal DAl inventories over the upper 200 m (our observed maximum SML depth) yield flux estimates that follow the expected seasonality of dust deposition in Bermuda, with ranges of 9.9-13 g/m2/y and 4.7-6.1 g/m2/y, using %AlS values derived from aerosol leaches using ultrapure water and 25% acetic acid, respectively. These values are ~5-10 times higher than our estimates based on aluminum in aerosols and rain, which average ~1.18 g/m2/y over our 318 day sampling period and are in accord with previous estimates of dust deposition at Bermuda. This discrepancy may reflect uncertainties in aerosol deposition velocity (assumed 1 cm/s), lateral advection of DAl in the region (assumed negligible), and, most likely, the residence time of DAl in the upper water column (assumed 5 years). The two different estimates can be brought into agreement if the residence time of DAl in the upper 200 m is increased to ~49 years or ~23 years, for %AlS values estimated by leaching aerosols with ultrapure water or 25% acetic acid, respectively. Such residence times for DAl in the upper 200 m are greater than a recent estimate for the North Atlantic based on thorium supply but appear compatible with values extracted from a recent data-assimilation modeling study.https://digitalcommons.odu.edu/gradposters2023_sciences/1000/thumbnail.jp

Potential Interactions Between Diatoms and Bacteria are Shaped by Trace Element Gradients in the Southern Ocean

The growth of diatoms in the Southern Ocean, especially the region surrounding the West Antarctic Peninsula, is frequently constrained by low dissolved iron and other trace metal concentrations. This challenge may be overcome by mutualisms between diatoms and co-occurring associated bacteria, in which diatoms produce organic carbon as a substrate for bacterial growth, and bacteria produce siderophores, metal-binding ligands that can supply diatoms with metals upon uptake as well as other useful secondary compounds for diatom growth like vitamins. To examine the relationships between diatoms and bacteria in the plankton (diatom) size class (\u3e 3 mu m), we sampled both bacterial and diatom community composition with accompanying environmental metadata across a naturally occurring concentration gradient of macronutrients, trace metals and siderophores at 21 stations near the West Antarctic Peninsula (WAP). Offshore Drake Passage stations had low dissolved iron (0.33 ± 0.15 nM), while the stations closer to the continental margin had higher dissolved iron (5.05 ± 1.83 nM). A similar geographic pattern was observed for macronutrients and most other trace metals measured, but there was not a clear inshore-offshore gradient in siderophore concentrations. The diatom and bacteria assemblages, determined using 18S and 16S rDNA sequencing respectively, were similar by location sampled, and variance in both assemblages was driven in part by concentrations of soluble reactive phosphorous, dissolved manganese, and dissolved copper, which were all higher near the continent. Some of the most common diatom sequence types observed were Thalassiosira and Fragilariopsis, and bacteria in the plankton size fraction were most commonly Bacteroidetes and Gammaproteobacteria. Network analysis showed positive associations between diatoms and bacteria, indicating possible in situ mutualisms through strategies such as siderophore and vitamin biosynthesis and exchange. This work furthers the understanding of how naturally occurring gradients of metals and nutrients influence diatom-bacteria interactions. Our data suggest that distinct groups of diatoms and associated bacteria are interacting under different trace metal regimes in the WAP, and that diatoms with different bacterial partners may have different modes of biologically supplied trace metals

Interactions of Bioactive Trace Metals in Shipboard Southern Ocean Incubation Experiments

In the Southern Ocean, it is well‐known that iron (Fe) limits phytoplankton growth. Yet, other trace metals can also affect phytoplankton physiology. This study investigated feedbacks between phytoplankton growth and dissolved Fe, manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in Southern Ocean shipboard incubations. Three experiments were conducted in September–October 2016 near the West Antarctic Peninsula: Incubations 1 and 3 offshore in the Antarctic Circumpolar Current, and Incubation 2 inshore in Bransfield Strait. Additions of Fe and/or vitamin B12 to inshore and offshore waters were employed and allowed assessment of metal (M) uptake relative to soluble reactive phosphorus (P) across a wide range of initial conditions. Offshore, treatments of \u3e1 nmol L−1 added Fe were Fe‐replete, whereas inshore waters were already Fe‐replete. Results suggest Mn was a secondary limiting nutrient inshore and offshore. No Fe‐vitamin B12 colimitation was observed. Overall, M:P uptake in the incubations was closely related to initial dissolved M:P for Fe, Mn, Co, Ni, and Cd, and for Cu inshore. Final concentrations of Fe and Zn were similar across light treatments of the experiments despite very different phytoplankton responses, and we observed evidence for Co/Cd/Zn substitution and for recycling of biogenic metals as inventories plateaued. In dark bottles, the absence of Mn oxidation may have allowed more efficient recycling of Fe and other trace metals. Our results provide insight into factors governing trace metal uptake, with implications for phytoplankton community composition locally and preformed micronutrient bioavailability in Southern Ocean water masses

Recommendations for best practice for iron speciation by competitive ligand exchange adsorptive cathodic stripping voltammetry with salicylaldoxime

The method of competitive ligand exchange followed by adsorptive cathodic stripping voltammetry (CLE-AdCSV) allows for the determination of dissolved iron (DFe) organic speciation parameters, i.e., ligand concentration (LFe) and conditional stability constant (log KFe′Lcond). Investigation of DFe organic speciation by CLE-AdCSV has been conducted in a wide range of marine systems, but aspects of its application pose challenges that have yet to be explicitly addressed. Here, we present a set of observations and recommendations to work toward establishing best practice for DFe organic speciation measurements using the added ligand salicylaldoxime (SA). We detail conditioning procedures to ensure a stable AdCSV signal and discuss the processes at play during conditioning. We also present step-by-step guidelines to simplify CLE-AdCSV data treatment and interpretation using the softwares ECDSoft and ProMCC and a custom spreadsheet. We validate our application and interpretation methodology with the model siderophore deferoxamine B (DFO-B) in a natural seawater sample. The reproducibility of our application and interpretation methodology was evaluated by running duplicate titrations on 19 samples, many of which had been refrozen prior to the duplicate analysis. Nevertheless, 50% of the duplicate analyses agreed within 10% of their relative standard deviation (RSD), and up to 80% within 25% RSD, for both LFe and log KFe′Lcond. Finally, we compared the sequential addition and equilibration of DFe and SA with overnight equilibration after simultaneous addition of DFe and SA on 24 samples. We found a rather good agreement between both procedures, with 60% of samples within 25% RSD for LFe (and 43% of samples for log KFe′Lcond), and it was not possible to predict differences in LFe or log KFe′Lcond based on the method applied, suggesting specific association/dissociation kinetics for different ligand assemblages. Further investigation of the equilibration kinetics against SA may be helpful as a potential way to distinguish natural ligand assemblages

Defining the Realized Niche of the Two Major Clades of \u3ci\u3eTrichodesmium\u3c/i\u3e: A Study on the West Florida Shelf

The cyanobacterium Trichodesmium plays an essential role supporting ocean productivity by relieving nitrogen limitation via dinitrogen (N-2) fixation. The two common Trichodesmium clades, T. erythraeum and T. thiebautii, are both observed in waters along the West Florida Shelf (WFS). We hypothesized that these taxa occupy distinct realized niches, where T. thiebautii is the more oceanic clade. Samples for DNA and water chemistry analyses were collected on three separate WFS expeditions (2015, 2018, and 2019) spanning multiple seasons; abundances of the single copy housekeeping gene rnpB from both clades were enumerated via quantitative PCR. We conducted a suite of statistical analyses to assess Trichodesmium clade abundances in the context of the physicochemical data. We observed a consistent coastal vs. open ocean separation of the two clades: T. erythraeum was found in shallow waters where the concentrations of dissolved iron (dFe) and the groundwater tracer Ba were significantly higher, while T. thiebautii abundance was positively correlated with water column depth. The Loop Current intrusion in 2015 with entrained Missisippi River water brought higher dFe and elevated abundance of both clades offshore of the 50 m isobath, suggesting that both clades are subject to Fe limitation on the outer shelf. Whereas, previous work has observed that T. thiebautii is more abundant than T. erythraeum in open ocean surface waters, this is the first study to examine Trichodesmium niche differentiation in a coastal environment. Understanding the environmental niches of these two key taxa bears important implications for their contributions to global nitrogen and carbon cycling and their response to global climate change

Authigenic Iron Is a Significant Component of Oceanic Labile Particulate Iron Inventories

Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile particulate material from refractory lithogenics. Direct measurements of cellular iron (Fe) were used to calculate the biogenic contribution to the labile Fe fraction, and any remaining labile material was defined as authigenic. Total particulate Fe (PFe) inventories varied \u3c15% between seasons despite strong seasonality in dust inputs. Across seasons, the total PFe inventory (±1SD) was composed of 73 ± 13% lithogenic, 18 ± 7% authigenic, and 10 ± 8% biogenic Fe above the deep chlorophyll maximum (DCM), and 69 ± 8% lithogenic, 30 ± 8% authigenic, and 1.1 ± 0.5% biogenic Fe below the DCM. Data from three other ocean regions further reveal the importance of the authigenic fraction across broad productivity and Fe gradients, comprising ca. 20%-27% of total PFe