Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Data from in situ pump profiler system collected on cruise HRS1415.

See Related Publicatons (below) for field papers published as a result of this project (methods included).

Description/methods for parameters measured:
C parameters performed by Dr. Wei-Jun Cai’s group for:
TA - Open cell Gran titration with semi-automatic AS-ALK2 Apollo Scitech titrator;
pH - glass electrode, NBS buffers;
DIC - infrared CO₂ analyzer (AS-C3, Apollo Scitech).
Use Dickson CRM for calibration. DIC/TA samples were filtered (0.45um) and fixed with 100 ul of saturated mercury bichloride.
Use the methods of Gran (1952) and Huang, et al. (2012).

Fe parameters:
The method of Stookey (1972) is used to determine dissolved Fe(II) and on addition if hydroxylamine Fe total. Fe(III) is determined by difference. Modified and calibrated by many including Lewis et al (2007) and MacDonald et al (2014). Typically, triplicate measurements performed.

Dissolved Mn parameters:
The porphyrin spectrophotometric method of Madison et al (2011) measures dissolved Mn(II), Mn(III) bound to weaker ligands and total Mn. Method includes calibration and intercomparison of totals with other instrumentation (ICP, AA).  Detection limit is 0.050 micromolar. Detection limit (DL) is 50 micromolar with a 1 cm path length cell.

Modification of Madison for Mn(III) bound to strong ligands by adding a reducing agent to a separate subsample with the porphyrin to obtain total Mn. Mn(III) bound to strong ligand complexes is determined by difference. Typically, triplicate measurements performed. Detection limit is 3.0 nanomolar.

MnO_x on unfiltered samples:
The leucoberbelein blue method is that of Altmann (1972) and Krumblein and Altmann (1973) in 1 cm cells, but can be modified for longer path length cells.

S parameters:
O₂, H₂S and polysulfides by the voltammetry method of Luther et al (2008).
A flow cell was also used to collect in situ O₂ and H₂S data as well as some additional samples. Analysis by voltammetry (Luther et al, 2008).
Solid and nanoparticulate S₈ (Yücel et al 2010 and Findlay et al 2014).
Typically, triplicate measurements performed. 

In situ pump profiler cast refers to profiling with a pump profiler for O₂ and H₂S using solid state gold-amalgam electrodes for voltammetry (Luther et al, 2008; Analytical Instrument Systems DLK-60) along with a temperature and salinity sensor from YSI. Water was pumped aboard to make measurements on discrete samples for Mn and Fe speciation as well. 

Methods papers used in this project (full citations in Related Publications section)
Dissolved Mn speciation parameters:
Madison et al. (2011)

Madison et al. (2013) 

Oldham et al. (2015)

Oldham et al. (2017)
[[ Here, we modified the method of Madison et al. (2011) for water column samples to achieve a detection limit of 3.0 nM (3 times the standard deviation of a blank) by using a 100-cm liquid waveguide capillary cell and the addition of a heating step as well as a strong reducing agent for Mn Speciation [Mn³⁺ = Mn_T – Mn²⁺]. See Table 1 in this paper for recovery tests. As weak Mn(III)-L complexes could not be measured in our previous work (Oldham et al, 2015; paper above), this method was used throughout this cruise. ]]

MnO_X solids:
Altmann (1972)

Krumbein & Altmann (1973)

Dissolved Fe speciation parameters:
Stookey (1970)

Lewis et al. (2007)

O₂ and H₂S, polysulfides:
Luther et al. (2008)

Luther et al. (2013)

S₈:
Yücel et al. (2010)

pH and inorganic carbon parameters:
Gran (1952)

Huang & Cai (2012)

BCO-DMO Processing:
- added column for cast (was contained in header rows);
- modified parameter names to conform with BCO-DMO naming conventions;
- formatted date to mm/dd/yyyy to match CTD dataset;
- replaced blanks/missing data with "nd" ("no data");
- replaced "ND" (in all caps) with "not_detected_or_BDL";
- replaced "NA" (in all caps) with "not_analyzed";
- coverted lat and lon from degrees and decimal minutes to decimal degrees;
- added date-time in ISO8601 format using original date and time_GMT fields.

Description from NSF award abstract:
The research conducted by investigators in the School of Marine Science and Policy at the University of Delaware and within the Department of Environmental and Biomolecular Systems of Oregon Health and Science University will examine the importance of soluble Mn(III) in the biogeochemical cycling of Mn. To date, most studies of Mn in marine environments have not considered Mn(III), the intermediate oxidation state between the soluble reduced state (Mn(II)) and the more insoluble oxidized state (Mn(IV)). The presence and stability of Mn(III) in marine systems, especially those where oxygen levels are reduced, changes the dynamics and stability, solubility and fate and transport of Mn in these locations, and at interfaces between oxic and low oxygen environments. This is not understood at present and the proposed research is poised to provide new information concerning the Mn cycle and is potentially transformative research. The PIs have developed new methods to examine Mn(III) levels in the environment and this capability will bolster the successful accomplishment of the project's goals. The studies will not only focus on understanding the cycling of Mn between its various oxidation states but will determine the concentration and distribution of Mn(III) in stratified coastal ocean waters and in sediment porewaters. The study will also examine the potentially important role of Mn(III) in mediating and influencing the biogeochemical cycling of Mn with that of Fe and S, which are both important components of the major ocean chemical cycles. A better understanding of the biogeochemistry of Mn will inform not only scientists interested in metal cycling in the ocean but also those focused on studies across redox transition zones. The proposed research has an international component and the investigators have developed plans to broadly disseminate their results to students at all levels and to the community. The Principal Investigators have a strong history in education and graduate student and post-doctoral support and mentoring and this will continue under the current grant.