Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Curation Notes
• Data Files
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Sample collection conducted as part of the National Geographic-Lindblad Expeditions Visiting Scientist Program.

Surface water samples (upper 1 m) were collected using pre-cleaned 2 L polycarbonate (PC) Nalgene bottles aboard a Zodiac boat. All samples were filtered through 0.7 μm Whatman GF/F filters followed by 0.2 μm Pall Supor membrane filters. Aliquots were collected for dissolved organic carbon (DOC) and nutrient analyses and stored at −20°C and 4°C, respectively. Filtrates were acidified to pH 2 with concentrated HCl, and dissolved organic matter (DOM) was isolated using solid-phase extraction (SPE) cartridges (Agilent Bond Elut PPL) and subsequently eluted with methanol. Extracts were stored frozen at −20°C until analysis.

Temperature and salinity were measured at the time of sample collection using a Sper Scientific temperature/salinity (T/S) sensor.

DOC and total dissolved nitrogen (TDN) concentrations were measured using a Shimadzu TOC-VCPH analyzer. Potassium hydrogen phthalate was used as the calibration standard for DOC, and potassium nitrate was used for TDN calibration curves.

Ammonium (NH₄⁺) concentrations were determined using the indophenol colorimetric method. Nitrate (NO₃⁻; nitrate plus nitrite) and phosphate (PO₄³⁻) concentrations were measured using cadmium reduction followed by diazotization and the molybdate blue method, respectively, with an Alpkem two-channel autoanalyzer.

This section documents curation actions performed prior to publication review with the submitter, and additional information relevant to understanding and reusing this dataset. It distinguishes changes made to the submitted (meta)data from unresolved issues and/or enhancements that improve future reuse and interoperability.

CURATION ACTIONS PERFORMED ON DATA
- Loaded WAP_2025_Environmental_Bulk analyses_BCO-DMO.xlsx.
- Cleaned excel file removing parameter unit row (added to parameters section) and reference to bdl.
- Converted combined Date and Time columns into a new ISO_DateTime_UTC datetime column, parsing input as America/Argentina/San_Juan local time and converting to UTC, formatted yyyy-mm-ddThh:mm
- Replaced "bdl*" values in NH4 column with "bdl" and treated as missing value
- Renamed resource wap_2025_environmental_bulk_analyses_bco-dmo-1 to 1008949_v1_dom_composition
- Renamed column "WAP Sites" to "WAP_Sites"
- Saved as final tables: 1008949_v1_dom_composition.csv

CURATION ACTIONS PERFORMED ON METADATA
- Standard metadata entry and text formatting steps were performed.

ISSUES POTENTIALLY IMPACTING REUSE
- NA

Glacier melting in polar regions can result in large amounts of freshwater being introduced into the coastal ocean, changing nutrient levels at the surface, impacting organisms like phytoplankton and influencing the distribution and composition of organic material in the water. In this project, researchers will participate in an expedition to the West Antarctic Peninsula in early 2025 that will approach several retreat glaciers, starting from the northern tip of the Peninsula and progressing toward its central region. The team will analyze physical, chemical, and biological changes in the area, and relate these changes to differences in melting trends that have been observed along the Peninsula. Results will help predict future impacts on the region due to increased melting associated with continued warming. The program will provide training for a graduate student and disseminate results of the study across a broad audience.

This project will examine the effects of meltwater input from tidewater glaciers on dissolved organic matter along the West Antarctic Peninsula. While glaciers near the northern tip of the Peninsula show no changes in grounding line discharge trends, several farther south, near Palmer Station, are characterized by significant changes, with discharge trends surging by a factor of 3 in many glaciers. This suggests a north-south gradient in the response of discharge rates to environmental forcing along the Peninsula, likely influencing the vertical flux of nutrients and affecting phytoplankton and the composition and lability of dissolved organic matter. The PIs will take advantage of a cruise-of-opportunity to the West Antarctic Peninsula in February 2025 to collect samples in transects approaching multiple tidewater glaciers, capturing the north-south gradient in discharge trends reported for the region. Samples of seawater and floating ice from glaciers will be analyzed for temperature, salinity, nutrients, chlorophyll, particulate and dissolved organic carbon concentrations and lability, and dissolved organic matter composition using ultrahigh-resolution mass spectrometry, optics and isotopic analyses. Variations in organic matter composition and lability will be identified and compared along the north-south gradient in discharge trends, which will inform how the system might respond to future increases in glacier melting. Results will also be compared with similar analyses currently being conducted in the Amundsen Sea and the Kerguelen Islands, collectively capturing the influence of meltwater originating from large ice sheets, tidewater glaciers and land-terminating glaciers. The project will support a graduate student who will be trained in the analysis of dissolved organic matter data.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.