Total dissolved mercury and methylmercury from rainfall samples collected on Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from Oct-Nov 2018

Website: https://www.bco-dmo.org/dataset/833393
Data Type: Cruise Results
Version: 1
Version Date: 2020-12-09

Project
» US GEOTRACES Pacific Meridional Transect (U.S. GEOTRACES PMT)
» US GEOTRACES Pacific Meridional Transect: Determination of the air-sea exchange of inorganic and methylated mercury in the anthropogenically-impacted and remote Pacific Ocean (PMT Mercury air-sea exchange)

Program
» U.S. GEOTRACES (U.S. GEOTRACES)
ContributorsAffiliationRole
Mason, Robert P.University of Connecticut (UConn)Principal Investigator
Rauch, ShannonWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
Total dissolved mercury and total dissolved methylmercury concentrations from rainfall samples collected on Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from Oct-Nov 2018.


Coverage

Spatial Extent: N:11 E:-151.951 S:-10.5 W:-152.016
Temporal Extent: 2018-10-30 - 2018-11-17

Acquisition Description

This dataset reports total dissolved mercury concentration and total dissolved methylmercury concentration in precipitation collected with an automated collector by the GEOTRACES atmospheric sampling group.

For Total Dissolved Mercury:
Rain was subsampled after collection for mercury analysis. The sample is identified by a GEOTRACES event ID. The samples were acidified on board and later analyzed for their total mercury concentration using standard techniques, as detailed in DiMento et al. (2019).

Total dissolved mercury is reported in units of pmol/L.
Detection limit = 0.8
Spike recovery (%) = 100.6±8.8

For Total Dissolved Methylmercury:
Rain was subsampled after collection for mercury analysis – both total Hg and methylmercury were analyzed from the same subsample. The sample is identified by a GEOTRACES event ID. The samples were acidified on board and later analyzed for their total mercury concentration using standard techniques, as detailed in DiMento et al. (2019).

Total dissolved methylmercury is reported in units of pmol/L.
Detection limit = 0.01
Spike recovery (%) = 124.1±6.5


Processing Description

BCO-DMO Processing:
- added date-time fields in ISO8601 format;
- applied GEOTRACES DOoR barcoded names;
- renamed fields to conform with BCO-DMO naming conventions.


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Related Publications

DiMento, B. P., Mason, R. P., Brooks, S., & Moore, C. (2019). The impact of sea ice on the air-sea exchange of mercury in the Arctic Ocean. Deep Sea Research Part I: Oceanographic Research Papers, 144, 28–38. doi:10.1016/j.dsr.2018.12.001
Methods

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Related Datasets

Continues
Mason, R. (2021) Total dissolved mercury and methylmercury from rainfall samples collected on Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from Sept-Oct 2018. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2020-12-09 doi:10.26008/1912/bco-dmo.833369.1 [view at BCO-DMO]
Relationship Description: GP15 was made up of two cruise legs, RR1814 (Leg 1) and RR1815 (Leg 2).

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Parameters

ParameterDescriptionUnits
Station_IDStation number unitless
Start_Date_UTCDate (UTC) at start of sample collection; format: DD/MM/YYYY unitless
Start_Time_UTCTime (UTC) at start of sample collection; format: hh:mm unitless
Start_ISO_DateTime_UTCDate and time (UTC) at start of sample collection; formatted to ISO8601 standard: YYYY-MM-DDThh:mmZ unitless
End_Date_UTCDate (UTC) at end of sample collection; format: DD/MM/YYYY unitless
End_Time_UTCTime (UTC) at end of sample collection; format: hh:mm unitless
End_ISO_DateTime_UTCDate and time (UTC) at end of sample collection; formatted to ISO8601 standard: YYYY-MM-DDThh:mmZ unitless
Start_LatitudeLatitude at start of sample collection degrees North
Start_LongitudeLongitude at start of sample collection degrees East
End_LatitudeLatitude at end of sample collection degrees North
End_LongitudeLongitude at end of sample collection degrees East
Event_IDEvent number unitless
Sample_IDGEOTRACES sample number unitless
Sample_DepthSample depth meters (m)
Hg_R_TD_CONC_AUTO_nvofuiTotal dissolved mercury concentration in precipitation, collected with an automated precipitation collector picomoles per liter (pmol/L)
SD1_Hg_R_TD_CONC_AUTO_nvofuiOne standard deviation of Hg_R_TD_CONC_AUTO_nvofui picomoles per liter (pmol/L)
Flag_Hg_R_TD_CONC_AUTO_nvofuiQuality flag for Hg_R_TD_CONC_AUTO_nvofui unitless
Hg_Me_R_TD_CONC_AUTO_8jctuqTotal dissolved methylmercury concentration in rainfall, collected with an automated precipitation collector picomoles per liter (pmol/L)
SD1_Hg_Me_R_TD_CONC_AUTO_8jctuqOne standard deviation of Hg_Me_R_TD_CONC_AUTO_8jctuq picomoles per liter (pmol/L)
Flag_Hg_Me_R_TD_CONC_AUTO_8jctuqQuality flag for Hg_Me_R_TD_CONC_AUTO_8jctuq unitless


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Instruments

Dataset-specific Instrument Name
Automated rain sampler
Generic Instrument Name
Precipitation Sampler
Generic Instrument Description
A device that collects a sample of precipitation (rain, hail or snow) as it falls.


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Deployments

RR1815

Website
Platform
R/V Roger Revelle
Report
Start Date
2018-10-24
End Date
2018-11-24
Description
Additional cruise information is available from the Rolling Deck to Repository (R2R): https://www.rvdata.us/search/cruise/RR1815


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Project Information

US GEOTRACES Pacific Meridional Transect (U.S. GEOTRACES PMT)


Coverage: Pacific Meridional Transect along 152W (GP15)


A 60-day research cruise took place in 2018 along a transect form Alaska to Tahiti at 152° W. A description of the project titled "Collaborative Research: Management and implementation of the US GEOTRACES Pacific Meridional Transect", funded by NSF, is below. Further project information is available on the US GEOTRACES website and on the cruise blog. A detailed cruise report is also available as a PDF.

Description from NSF award abstract:
GEOTRACES is a global effort in the field of Chemical Oceanography in which the United States plays a major role. The goal of the GEOTRACES program is to understand the distributions of many elements and their isotopes in the ocean. Until quite recently, these elements could not be measured at a global scale. Understanding the distributions of these elements and isotopes will increase the understanding of processes that shape their distributions and also the processes that depend on these elements. For example, many "trace elements" (elements that are present in very low amounts) are also important for life, and their presence or absence can play a vital role in the population of marine ecosystems. This project will launch the next major U.S. GEOTRACES expedition in the Pacific Ocean between Alaska and Tahiti. The award made here would support all of the major infrastructure for this expedition, including the research vessel, the sampling equipment, and some of the core oceanographic measurements. This project will also support the personnel needed to lead the expedition and collect the samples.

This project would support the essential sampling operations and infrastructure for the U.S. GEOTRACES Pacific Meridional Transect along 152° W to support a large variety of individual science projects on trace element and isotope (TEI) biogeochemistry that will follow. Thus, the major objectives of this management proposal are: (1) plan and coordinate a 60 day research cruise in 2018; (2) obtain representative samples for a wide variety of TEIs using a conventional CTD/rosette, GEOTRACES Trace Element Sampling Systems, and in situ pumps; (3) acquire conventional CTD hydrographic data along with discrete samples for salinity, dissolved oxygen, algal pigments, and dissolved nutrients at micro- and nanomolar levels; (4) ensure that proper QA/QC protocols are followed and reported, as well as fulfilling all GEOTRACES intercalibration protocols; (5) prepare and deliver all hydrographic data to the GEOTRACES Data Assembly Centre (via the US BCO-DMO data center); and (6) coordinate all cruise communications between investigators, including preparation of a hydrographic report/publication. This project would also provide baseline measurements of TEIs in the Clarion-Clipperton fracture zone (~7.5°N-17°N, ~155°W-115°W) where large-scale deep sea mining is planned. Environmental impact assessments are underway in partnership with the mining industry, but the effect of mining activities on TEIs in the water column is one that could be uniquely assessed by the GEOTRACES community. In support of efforts to communicate the science to a wide audience the investigators will recruit an early career freelance science journalist with interests in marine science and oceanography to participate on the cruise and do public outreach, photography and/or videography, and social media from the ship, as well as to submit articles about the research to national media. The project would also support several graduate students.


US GEOTRACES Pacific Meridional Transect: Determination of the air-sea exchange of inorganic and methylated mercury in the anthropogenically-impacted and remote Pacific Ocean (PMT Mercury air-sea exchange)


Coverage: Pacific Ocean Alaska (Aleutian Islands to Tahiti along 150 W, 55 N to 20 S)


NSF Award Abstract:
Human activity has greatly increased the amount of mercury (Hg) in the environment, and particularly in the surface ocean. Most of the Hg enters the ocean from the atmosphere as a gas, on particles, or in precipitation. Complex physical and chemical processes at the interface between the ocean and atmosphere control the amount of Hg that is retained and therefore that can ultimately accumulate in seafood. Methylmercury (MeHg) is a chemical form of Hg that is commonly retained in organisms and impacts the health and development of humans and wildlife. This research will assess concentrations of Hg together with its "methyl" forms in the atmosphere and surface ocean at sea from Alaska to Tahiti. The spatial extent of the cruise will allow comparison of the air-sea exchange and concentrations of mercury in both the North Pacific where human emissions are large and in remote regions with minimal human impact. The researchers will use established techniques and develop new methods to examine the fate and transport of mercury within the surface ocean. These findings will contribute key Hg data to the GEOTRACES program and thus enhance its overall impact as part of an extensive marine trace element study. Findings will have potential to inform public policy and global environmental treaties related to Hg, thus providing data to evaluate human risk from Hg in present and future climate scenarios. Educational impact will include support for a graduate student and their dissertation using the field data, as well as several undergraduates that will gain high level, hands-on research experience.

The research will take advantage of recent analytical advances that enable high resolution determination of the concentrations and forms of inorganic Hg in the surface ocean and atmosphere. The analytical approach will also be expanded to include measurements of methylated Hg compounds, including MeHg and dimethylmercury. These measurements, and ancillary data collected during the GEOTRACES Pacific Meridional Transect cruise, will allow assessment of both atmospheric input and in situ oceanic loss for the dominant forms of inorganic and methylated Hg. Exchange will also be evaluated in the context of the suite of environmental variables collected by collaborators during the cruise. The resulting data will help assess the long-term impact of anthropogenic inputs of Hg to the atmosphere and ocean, and the factors that influence the loss of Hg from the ocean by gas evasion. The studies will build on previous results obtained as part of the GEOTRACES program and other NSF-funded studies, adding novel measurements and building an enhanced understanding of the sources and sinks of Hg to the open ocean.



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Program Information

U.S. GEOTRACES (U.S. GEOTRACES)


Coverage: Global


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.



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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