Table of Contents

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

Bottle data from the GTC CTD using the GEOTRACES Clean Carousel sampling system (GTC), GEOTRACES Arctic cruise HLY1502.

GTC CTD BOTTLE file name from the Scripps Oceanographic Data Facility (ODF): 20160609ODU

Note: 'FLAG_W' columns correspond to the WHP (WOCE Hydrographic Program) quality flag scheme.

The Go-Flo bottles were rearranged between casts to eliminate the possibility of sampling bias. See the HLY1502 cruise report for more information on data acquisition.

NOTE: Station 4 cast 3 was abandoned due to non-tripped bottles (note the BTLNBR_FLAG_W values of "9") and repeated as Station 4 cast 5 using the same sample numbers. Disregard information for samples 10611, 10610, 10609, 10608, 10607, and 10606 where CASTNO = 3.

Version history:
2019-07-29: version 4: removed all "placeholder" columns containing no data (-999 only). These columns were included in the original files from ODF to indicate the expected datasets. All data reported from the cruise can by found on the HLY1502 cruise page or on the U.S. Arctic GEOTRACES project page.

2017-05-01: new version (3) served on 2017-05-01] replaces v2: 2016-06-09. Event 6079 was revised and event 6369 was added back to the file. It was present in version 2016-05-17 but missing in version 2016-06-09. SOLUBLE_TH and SOLUBLE_TH_FLAG_W contain no data so blanks were replaced with nd for 'no data'.

2016-06-09: new version (2) served [2016-06-09], replaces v:2016-05-17.

2016-05-17: version 1 served.

BCO-DMO Processing:
- added conventional header with dataset name; PI name; version date;
- added cruise_id column;
- reformatted time as HHMM;
- changed all hyphen, slash, and decimal points in parameter names to underscores (changed TH-232_COLL_0.02MICR to TH_232_COLL_02MICR);
- hour=2400 not legal time; changed day by one and time to 0000 (only for station 41/cast 3/event 6277);
- ZN_DISS and ZN_DISS_FLAG_W duplicated - removed pair with no data;
- 2019-07-29: removed all "placeholder" columns containing no data (-999 only); a list of the removed columns available as a tab-separated file: GTC_Bottle_Removals_20190729.tsv

Description from NSF award abstract:
In pursuit of its goal "to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions", in 2015 the International GEOTRACES Program will embark on several years of research in the Arctic Ocean. In a region where climate warming and general environmental change are occurring at amazing speed, research such as this is important for understanding the current state of Arctic Ocean geochemistry and for developing predictive capability as the regional ecosystem continues to warm and influence global oceanic and climatic conditions. The three investigators funded on this award, will manage a large team of U.S.scientists who will compete through the regular NSF proposal process to contribute their own unique expertise in marine trace metal, isotopic, and carbon cycle geochemistry to the U.S. effort. The three managers will be responsible for arranging and overseeing at-sea technical services such as hydrographic measurements, nutrient analyses, and around-the-clock management of on-deck sampling activites upon which all participants depend, and for organizing all pre- and post-cruise technical support and scientific meetings. The management team will also lead educational outreach activities for the general public in Nome and Barrow, Alaska, to explain the significance of the study to these communities and to learn from residents' insights on observed changes in the marine system. The project itself will provide for the support and training of a number of pre-doctoral students and post-doctoral researchers. Inasmuch as the Arctic Ocean is an epicenter of global climate change, findings of this study are expected to advance present capability to forecast changes in regional and globlal ecosystem and climate system functioning.

As the United States' contribution to the International GEOTRACES Arctic Ocean initiative, this project will be part of an ongoing multi-national effort to further scientific knowledge about trace elements and isotopes in the world ocean. This U.S. expedition will focus on the western Arctic Ocean in the boreal summer of 2015. The scientific team will consist of the management team funded through this award plus a team of scientists from U.S. academic institutions who will have successfully competed for and received NSF funds for specific science projects in time to participate in the final stages of cruise planning. The cruise track segments will include the Bering Strait, Chukchi shelf, and the deep Canada Basin. Several stations will be designated as so-called super stations for intense study of atmospheric aerosols, sea ice, and sediment chemistry as well as water-column processes. In total, the set of coordinated international expeditions will involve the deployment of ice-capable research ships from 6 nations (US, Canada, Germany, Sweden, UK, and Russia) across different parts of the Arctic Ocean, and application of state-of-the-art methods to unravel the complex dynamics of trace metals and isotopes that are important as oceanographic and biogeochemical tracers in the sea.

GEOTRACES is a SCOR sponsored program; and funding for program infrastructure development is provided by the U.S. National Science Foundation.

GEOTRACES gained momentum following a special symposium, S02: Biogeochemical cycling of trace elements and isotopes in the ocean and applications to constrain contemporary marine processes (GEOSECS II), at a 2003 Goldschmidt meeting convened in Japan. The GEOSECS II acronym referred to the Geochemical Ocean Section Studies To determine full water column distributions of selected trace elements and isotopes, including their concentration, chemical speciation, and physical form, along a sufficient number of sections in each ocean basin to establish the principal relationships between these distributions and with more traditional hydrographic parameters;

* To evaluate the sources, sinks, and internal cycling of these species and thereby characterize more completely the physical, chemical and biological processes regulating their distributions, and the sensitivity of these processes to global change; and

* To understand the processes that control the concentrations of geochemical species used for proxies of the past environment, both in the water column and in the substrates that reflect the water column.

GEOTRACES will be global in scope, consisting of ocean sections complemented by regional process studies. Sections and process studies will combine fieldwork, laboratory experiments and modelling. Beyond realizing the scientific objectives identified above, a natural outcome of this work will be to build a community of marine scientists who understand the processes regulating trace element cycles sufficiently well to exploit this knowledge reliably in future interdisciplinary studies.

Expand "Projects" below for information about and data resulting from individual US GEOTRACES research projects.