| Contributors | Affiliation | Role |
|---|---|---|
| Sipler, Rachel E. | Virginia Institute of Marine Science (VIMS) | Principal Investigator, Contact |
| Bronk, Deborah A. | Virginia Institute of Marine Science (VIMS) | Co-Principal Investigator |
| Yager, Patricia L. | University of Georgia (UGA) | Co-Principal Investigator |
| York, Amber D. | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
This dataset contains nitrogen fixation rates, as well as ammonium, nitrate, and phosphate concentrations collected in the coastal Chukchi Sea west of Barrow, Alaska between 15 Aug 2011 and 20 Aug 2011. Salinity, temperature, and collection depth are also provided.
Nitrogen fixation rates were calculated according to Montoya et al. (1996) and are reported as the average +- the standard error for each site (n=3). Sampling methodology and other analytical procedures are described in detail in Baer et al (2017).
BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* data with value "surface" in collection depth column changed to 0
* Added ISO_DateTime_UTC from UTC_Time and date_local fields
* latitude and longitude converted to decimal degrees from degrees minutes seconds.
| File |
|---|
N_fix.csv (Comma Separated Values (.csv), 2.17 KB) MD5:5c302c5f44b559a434362416e3c696bd Primary data file for dataset ID 701789 |
| Parameter | Description | Units |
| Sample_ID | Station number (name) | unitless |
| Date_local | Date of sample collection (time zone AKDT, UTC-8) | unitless |
| Time_local | Time of sample collection (time zone AKDT, UTC-8) | unitless |
| ISO_DateTime_UTC | Date and time of sample collection (UTC) in ISO 8601:2004(E) format YYYY-MM-DDThh:mmZ | unitless |
| Latitude | Latitude of sample collection | decimal degrees |
| Longitude | Longitude of sample collection; West is negative | decimal degrees |
| Depth | Water Column Depth (Bottom depth) | meters (m) |
| Collection_Depth | Depth of sample collection | meters (m) |
| Size_fraction | Size Fraction | micrometer (um) |
| Temperature | Temperature | degrees Celsius |
| Salinity | Salinity | Practical Salinity Units (PSU) |
| N_Fixation_Rate_Absolute | Absolute Nitrogen fixation rate | micromoles per liter per hour (umol/L/h) |
| Nitrogen_Fixation_Rate_SE | Nitrogen fixation rate standard error | micromoles per liter per hour (umol/L/h) |
| Ammonium | Ammonium concentration [NH4] | micromolar (umol/L) |
| Ammonium_SD | Ammonium concentration [NH4] standard deviation | micromolar (umol/L) |
| Nitrate | Nitrate concentration [NO3] | micromolar (umol/L) |
| Nitrate_SD | Nitrate concentration [NO3] standard deviation | micromolar (umol/L) |
| Phosphate | Phosphate concentration [PO4] | micromolar (umol/L) |
| Phosphate_SD | Phosphate concentration [PO4] standard deviation | micromolar (umol/L) |
| Dataset-specific Instrument Name | Shimadzu UV-1601 spectrophotometer |
| Generic Instrument Name | UV Spectrophotometer-Shimadzu |
| Dataset-specific Description | Ammonium concentrations were measured on a Shimadzu UV-1601 spectrophotometer. |
| Generic Instrument Description | The Shimadzu UV Spectrophotometer is manufactured by Shimadzu Scientific Instruments (ssi.shimadzu.com). Shimadzu manufacturers several models of spectrophotometer; refer to dataset for make/model information. |
| Dataset-specific Instrument Name | Lachat QuickChem 8500 autoanalyzer |
| Generic Instrument Name | Flow Injection Analyzer |
| Dataset-specific Description | Nitrate and phosphate were measured using a Lachat QuikChem 8500 autoanalyzer. |
| Generic Instrument Description | An instrument that performs flow injection analysis. Flow injection analysis (FIA) is an approach to chemical analysis that is accomplished by injecting a plug of sample into a flowing carrier stream. FIA is an automated method in which a sample is injected into a continuous flow of a carrier solution that mixes with other continuously flowing solutions before reaching a detector. Precision is dramatically increased when FIA is used instead of manual injections and as a result very specific FIA systems have been developed for a wide array of analytical techniques. |
| Dataset-specific Instrument Name | Europa GEO 20/20 |
| Generic Instrument Name | Mass Spectrometer |
| Dataset-specific Description | Isotopic measurements for 15N fixation rates were analyzed on a Europa GEO 20/20 mass spectrometer with an ANCA-SL autosampler. |
| Generic Instrument Description | General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components. |
| Website | |
| Platform | ArcticNitro |
| Start Date | 2010-08-30 |
| End Date | 2012-01-19 |
| Description | Extracted from the NSF proposalStudy sites: Because of its unique combination of year-round access to the coastal Arctic Ocean
and strong scientific support system (Barrow Arctic Science Consortium we propose to make our
primary winter and summer measurements from Barrow, Alaska.
At 71°N, Barrow receives 24- hour sunlight between May 10 and August 2, and is in 24-h darkness
between November 18 and January 24. Less than 1 km from shore, shelf depths exceed 10m, and
significantly deeper waters (>100 m) are not far away. Twice each year (January and July) for
two years, working from Barrow, we will use either small boat or skidoo to travel offshore to
sample seawater. We anticipate having access to surface waters of 10-20 m depth within a mile
of the town of Barrow. We plan to sample biological and biogeochemical inventories along three
offshore transects, with 3-5 depths that sample through the surface mixed layer and into the
subsurface layer, accessing both the eastward coastal and the offshore westward currents (Weingartner 2006).
More extensive rate measurements and incubation studies will be made at selected sites and depths
The rationale for the transects is to sample the microbial community response to the cross-shelf
and depth gradients DIN availability. Nearshore stations will be N-limited throughout the water
column in the summer. Offshore stations may have significant NO3 below summer stratification.
As part of SNACS (Study of the Northern Alaska Coastal) C. Ashjian and colleagues have recently
completed summer research near Barrow, using small (43’) boats to investigate environmental controls
on zooplankton populations. They will have nutrient profiles offshore, which will help guide our study.
During the summer, we will coordinate with native Inupiat subsistence whalers (Barrow Whaling Captain
Association. In the winter, safe travel over the ice by foot or snow machine, as far out as the nearshore
lead, will offer access to the ocean using an ice auger. We will not be able to sample far offshore
during winter, but gradients will be weaker due to mixing. |
The Arctic is changing. Warm air is melting the sea ice at an accelerating pace, impacting the marine ecosystem. Further changes on land mean higher river discharge, rising seas, thawing of permafrost, and coastal erosion.
For the Arctic continental shelf, these physical changes impact the creatures that live there in major ways, ultimately altering the pathways and magnitude of energy transfer to fish, sea birds and marine mammals, and impacting the people dependant on those resources. Our challenge today is to understand what is happening in specific Arctic ecosystems to assess future change.
Understanding the microorganisms in Arctic coastal ecosystems is important because microbes dominate the biological biomass, production, and remineralization in marine systems. They are the "composters." Microbes are also the major producers and consumers of carbon dioxide and other greenhouse gases.
This study is focused on the climate-sensitive relationship between these microbes -- particularly the competition for nitrogen between phytoplankton/algae and bacteria -- and the productivity of the food web that depends on these organisms.
| Funding Source | Award |
|---|---|
| NSF Arctic Sciences (NSF ARC) |