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RRS Discovery D373
Cruise summary report
Cruise Info. | |
Ship name (ship code) | RRS Discovery (74E3) |
Cruise identifier | D373 |
Cruise period | 2011-12-07 — 2012-01-28 |
Status | Completed |
Port of departure | Balboa, Panama |
Port of return | Salina Cruz, Mexico |
Purpose | Research |
Objectives | With this research cruise we aim to study N cycle in a non- yet characterized OMZ, the Eastern Tropical North Pacific (ETNP). The overall aim of this project is to link N cycling to bacterial gene diversity and expression across a gradient of OMZ intensity in the East Tropical North Pacific (ETNP). Firstly by characterization of the water column (e.g. N2O, CO2, CH4 profiles) and then experimental manipulations to test if the ratio of N2 to N2O production is 'fixed' or 'flexible', screening for N2 production coupled to 15N organic-N and a molecular analysis of the active communities involved in the metabolism of these gases. In order to determine the extent of variation and potential within the water column, we performed experiments at 6 different sites, outside, on the edge and within the core OMZ. Understanding this response will help to us to predict the conditions under which N2O accumulates and will further clarify the mechanisms of fine tuning of the nitrogen cycle in the global ocean.
In addition, we set up experiments for the measurement of anaerobic methane oxidation, methane oxidation rates and tracing of the oxidised carbon into end products of methane oxidation by 13C-labelling in seawater samples. This will offer insights into carbon cycling in this area of the ocean. |
Chief scientist | Mark Trimmer (Queen Mary University of London School of Biological and Chemical Sciences) |
Cruise report | (1.48 MB) |
Ocean/sea areas | |
General | North East Pacific Ocean (limit 180W) |
Specific | Eastern Tropical North Pacific |
Track charts | (0.08 MB) |
Measurements | |
Physical oceanography | |
Surface measurements underway (T,S) | Quantity: number of track lines = 1 Description: Underway measurements from the non-toxic supply |
CTD stations | Quantity: number of profiles = 21 Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS |
CTD stations | Quantity: number of stations = 3 Description: Seawater samples sealed in serum bottles, transferred to the lab for measuring CH4 production with GC |
CTD stations | Quantity: number of profiles = 10 Description: Addition of 13CH4 and 15NO2- to water samples, onboard incubation and transfer to the lab for IRMS analysis of CO2 and N2 |
CTD stations | Quantity: number of profiles = 21 Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS |
CTD stations | Quantity: number of profiles = 21 Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab |
CTD stations | Quantity: number of profiles = 24 Description: Organic N stable isotopes addition in seawater samples and incubation on-board; transfer to the lab to measure N2 production by IRMS |
CTD stations | Quantity: number of profiles = 30 Description: Treatment with pre-mixed gases/15NO2- addition in seawater samples and incubation on-board; transfer to the lab to measure N2 and N2O production by IRMS |
CTD stations | Quantity: number of profiles = 30 Description: 15NO3- or 15NO2- stable isotope additions to seawater samples and incubation onboard, discrete samples returned for onshore analysis of NO3-, NO2- & NH4+ by IRMS to determine N cycling pathways |
CTD stations | Quantity: number of profiles = 42 Description: Transect CTD casts for continuous oxygen measurements in between stations, 10 m-surface-150 m |
CTD stations | Quantity: number of profiles = 139 Description: Water samples from chosen depths were preserved and transferred to the lab for measurement of δ13C values of CH4 |
CTD stations | Quantity: number of profiles = 237 Description: Discrete CTD water samples were taken for analysis on shore of natural abundance isotopes of NO3- and NO2- |
CTD stations | Quantity: number of profiles = 345 Description: CTD profiles - vertical profiles of NH4+ in water column, measured using Turner fluorometer |
CTD stations | Quantity: number of profiles = 460 Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC |
CTD stations | Quantity: number of profiles = 460 Description: CTD profiles - vertical profiles of DON in water column, to be analysed in the lab using Skalar |
CTD stations | Quantity: number of profiles = 460 Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar |
Chemical oceanography | |
Oxygen | Quantity: number of profiles = 42 Description: Transect CTD casts for continuous oxygen measurements in between stations, 10 m-surface-150 m |
Oxygen | Quantity: number of deployments = 1 Description: Scanfish deployed for continuous oxygen measurements. Unfortunately, scanfish was lost in the ocean. |
Carbon dioxide | Quantity: number of profiles = 21 Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab |
Carbon dioxide | Quantity: number of profiles = 21 Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS |
Carbon dioxide | Quantity: number of profiles = 460 Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC |
Other dissolved gases | Quantity: number of profiles = 21 Description: Addition of 12CH4 gas to water samples and incubation on board, measuring changes in concentrations of CH4 and CO2 with GC on board and finally on shore/in the lab |
Other dissolved gases | Quantity: number of stations = 3 Description: Seawater samples sealed in serum bottles, transferred to the lab for measuring CH4 production with GC |
Other dissolved gases | Quantity: number of profiles = 460 Description: CTD vertical profiles of CO2, CH4, N2O in water column, measured using GC |
Phosphate | Quantity: number of profiles = 460 Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar |
Nitrate | Quantity: number of profiles = 460 Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar |
Nitrite | Quantity: number of profiles = 460 Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar |
Total - N | Quantity: number of profiles = 460 Description: CTD profiles - vertical profiles of DON in water column, to be analysed in the lab using Skalar |
Ammonia | Quantity: number of profiles = 460 Description: CTD profiles - NO2, NO3, PO4, NH4+ in water column, measured using Skalar |
Ammonia | Quantity: number of profiles = 345 Description: CTD profiles - vertical profiles of NH4+ in water column, measured using Turner fluorometer |
Isotopes | Quantity: number of profiles = 21 Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS |
Isotopes | Quantity: number of profiles = 24 Description: Organic N stable isotopes addition in seawater samples and incubation on-board; transfer to the lab to measure N2 production by IRMS |
Isotopes | Quantity: number of profiles = 30 Description: Treatment with pre-mixed gases/15NO2- addition in seawater samples and incubation on-board; transfer to the lab to measure N2 and N2O production by IRMS |
Isotopes | Quantity: number of profiles = 30 Description: 15NO3- or 15NO2- stable isotope additions to seawater samples and incubation onboard, discrete samples returned for onshore analysis of NO3-, NO2- & NH4+ by IRMS to determine N cycling pathways |
Isotopes | Quantity: number of profiles = 6 Description: Seawater samples from CTD collected for incubations with labelled 13C compounds to carry out stable isotope probing (SIP) techniques onshore |
Isotopes | Quantity: number of profiles = 10 Description: Addition of 13CH4 and 15NO2- to water samples, onboard incubation and transfer to the lab for IRMS analysis of CO2 and N2 |
Isotopes | Quantity: number of profiles = 139 Description: Water samples from chosen depths were preserved and transferred to the lab for measurement of δ13C values of CH4 |
Isotopes | Quantity: number of profiles = 237 Description: Discrete CTD water samples were taken for analysis on shore of natural abundance isotopes of NO3- and NO2- |
Isotopes | Quantity: number of profiles = 21 Description: Addition of 13CH4 gas to water samples and incubation on board, transfer to the lab to measure 13CO2 production with IRMS |
Biology and fisheries | |
Phytoplankton | Quantity: number of samples = 35 Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis |
Zooplankton | Quantity: number of samples = 35 Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis |
Pelagic bacteria/micro-organisms | Quantity: number of profiles = 31 Description: Seawater from CTD filtered for onshore DNA and RNA analysis to look for bacterial community composition and dynamics |
Pelagic bacteria/micro-organisms | Quantity: number of samples = 35 Description: SAPs deployment; filters transferred to the lab for bacterioplankton, phytoplankton and zooplankton analysis |
Pelagic bacteria/micro-organisms | Quantity: number of profiles = 6 Description: Seawater samples from CTD collected for incubations with labelled 13C compounds to carry out stable isotope probing (SIP) techniques onshore |
Pelagic bacteria/micro-organisms | Quantity: number of profiles = 6 Description: Bacterial cells fixed from seawater samples for fluorescent in-situ hybridisation (FISH) and microscopy |
Pelagic bacteria/micro-organisms | Quantity: number of profiles = 21 Description: Addition of saturated 13CH4 solution to water samples and incubation on board, transfer to the lab to filter samples and measure the assimilation of 13C to the biomass of bacteria with IRMS |
Meteorology | |
Routine standard measurements | Quantity: number of track lines = 1 Description: Ship-mounted meteorological sensors |