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   set  data   graph     files  public Sediment trap flux measurements from the Hawaii Ocean Time-Series (HOT) project at station
ALOHA.
   ?     I   M   background (external link) RSS Subscribe BCO-DMO bcodmo_dataset_737393

The Dataset's Variables and Attributes

Row Type Variable Name Attribute Name Data Type Value
attribute NC_GLOBAL access_formats String .htmlTable,.csv,.json,.mat,.nc,.tsv,.esriCsv,.geoJson
attribute NC_GLOBAL acquisition_description String Particle flux was measured at a standard reference depth of 150 m using
multiple cylindrical particle interceptor traps deployed on a free-floating
array for approximately 60 h during each cruise. Sediment trap design and
collection methods are described in Winn et al. (1991). Samples were analyzed
for particulate C, N, P & Si. Typically six traps are analyzed for PC and PN,
three for PP, and another three traps for PSi.

The information below has been copied from the HOT Field & Laboratory
Protocols page, found at
[http://hahana.soest.hawaii.edu/hot/protocols/protocols.html#](\\"http://hahana.soest.hawaii.edu/hot/protocols/protocols.html#\\")
(last visited on 2018-05-23).

SUMMARY: Passively sinking particulate matter is collected using a free-
floating sediment array and, after prescreening (335 \u00b5m) to remove
zooplankton and micronekton carcasses, the sample materials are analyzed for
C, N, P and mass flux (mg m-2 d-1).

1\. Principle
Although most of the particulate matter both on the seafloor and in
suspension in seawater is very fine, recent evidence suggests that most of the
material deposited on the benthos arrives via relatively rare, rapidly sinking
large particles (McCave, 1975). Therefore, in order to describe adequately the
ambient particle field and to understand the rates and mechanisms of
biogeochemical cycling in the marine environment, it is imperative to employ
sampling methods that enable the investigator to distinguish between the
suspended and sinking pools of particulate matter. This universal requirement
for a careful and comprehensive analysis of sedimenting particles has resulted
in the development, evaluation and calibration of a variety of in situ
particle collectors or sediment traps. The results, after nearly a decade of
intensive field experiments, have contributed significantly to our general
understanding of: (1) the relationship between the rate of primary production
and downward flux of particulate organic matter, (2) mesopelagic zone oxygen
consumption and nutrient regeneration, (3) biological control of the removal
of abiogenic particles from the surface ocean and (4) seasonal and interannual
variations in particle flux to the deep-sea. Future sediment trap studies
will, most likely, continue to provide novel and useful data on the rates and
mechanisms of important biogeochemical processes.
At Station ALOHA, we presently deploy a free-drifting sediment trap array
with 12 individual collectors positioned at 150, 300 and 500 m. The deployment
period is generally 72 hours. The passively sinking particles are subsequently
analyzed for a variety of chemical properties, including: total mass, C, N and
P.
2. Precautions
Because particle fluxes in oligotrophic habitats are expected to be low,
special attention must be paid to the preparation of individual sediment trap
collector tubes so that they are clean and free of dust and other potentially
contaminating particles. Traps should be capped immediately after filling and
immediately after retrieval. Pay particular attention to airborne and/or
shipboard particulate contamination sources. In addition, the time interval
between trap retrieval and subsample filtration should be minimized in order
to limit the inclusion of extraneous abiotic particles and the post-collection
solubilization of particles.
3. Field Operations
3.1.
Hardware
Our free-floating sediment trap array is patterned after the MULTITRAP
system pioneered by Knauer et al. (1979) and used extensively in the decade-
long VERTEX program. Twelve individual sediment trap collectors (0.0039 m2)
are typically deployed at three depths (150, 300 and 500 m). The traps are
affixed to a PVC cross attached to 1/2\" polypropylene line. The traps are
tracked using VHF radio and Argos satellite transmitters and strobelights.
Typically we deploy our traps for a period of 72 hours each cruise.
3.2.
Trap solutions
Prior to deployment, each trap is cleaned with 1 M HCl, rinsed thoroughly
with deionized water then filled with a high density solution to prevent
advective-diffusive loss of extractants and preservatives during the
deployment period and to eliminate flushing of the traps during recovery
(Knauer et al., 1979). The trap solution is prepared by adding 50 g of NaCl to
each liter of surface seawater. This brine solution is pressure filtered
sequentially through a 1.0 and 0.5 \u00b5m filter cartridge prior to the
addition of 10 ml 100% formalin l-1. Individual traps are filled and at least
10 l of the trap solution is saved for analysis of solution blanks (see
sections 4.1 and 5.1).
3.3.
Post-recovery processing
3.3.1.
Upon recovery, individual traps are capped and transported to the shipboard
portable laboratory for analysis. Care is taken not to mix the higher density
trap solutions with the overlying seawater. Trap samples are processed from
deep to shallow in order to minimize potential contamination.
3.3.2.
The depth of the interface between the high density solution and overlying
seawater is marked on each trap. The overlying seawater is then aspirated with
a plastic tube attached to a vacuum system in order to avoid disturbing the
high density solution. Because some sinking particulate material collects near
the interface between the high density solution and the overlying seawater,
the overlying seawater is removed only to a depth that is 5 cm above the
previously identified interface.
3.3.3.
After the overlying seawater has been removed from all the traps at a given
depth, the contents of each trap is passed through an acid rinsed 335 \u00b5m
NitexR screen to remove contaminating zooplankton and micronekton which
entered the traps in a living state and are not truly part of the passive
flux. Immediately before this sieving process, the contents of each trap are
mixed to disrupt large amorphous particles. The traps are rinsed with a
portion of the <335 \u00b5m sample in order to recover all particulate matter,
and the 335 \u00b5m NitexR screen is examined to determine whether residual
material, in addition to the so-called \"swimmers\", is present. If so, the
screens are rinsed again with a portion of the 335 \u00b5m filtrate. After all
traps from a given depth have been processed, the 335 \u00b5m screen is
removed and placed into a vial containing 20 ml of formalin- seawater
solution, and stored at 4 \u00b0C for subsequent microscopic examination and
organism identification and enumeration.
4. Determination of Mass Flux
4.1.
Three of the 12 traps deployed at each water depth are used for the
determination of mass flux. At our shore-based laboratory, triplicate 250 ml
subsamples of the time-zero high density trap solution (blank) and equivalent
volumes individual traps (start with the deepest depth and work up), are
vacuum filtered through tared 25 mm 0.2 \u00b5m Nuclepore membrane filters
(see Chapter 18, sections 4.1.4 to 4.1.3). The tared filters are prepared as
follows:
4.1.1.
Rinse filters three times with distilled water. Place rinsed filter on a 2.5
cm2 foil square (to reduce static electricity) in a plastic 47 mm petri dish.
4.1.2.
Fold the foil in half over the filter and place the petri dish in a drying
oven with the lid ajar for 2 hours at 55 \u00b0C. Remove and cool in
dessicator for 30 minutes.
4.1.3.
Weigh filter to constant weight (i.e., repeat oven drying, cooling and
weighing until a relative standard deviation of <0.005% is achieved), on a
microbalance capable of 0.1 \u00b5g resolution. Record weights (to the nearest
0.1 \u00b5g) on label tape placed on top of the petri dish.
4.2.
After the last of the sample has passed through the filter, the walls of the
filter funnel are washed with three consecutive 5 ml rinses of an isotonic (1
M) ammonium formate solution to remove seawater salts. During each rinse,
allow the ammonium formate solution to completely cover the filter.
4.3.
Return the processed filter to its petri dish, record sample number (on the
dish and data sheet), and place in a drying oven at 55 \u00b0C for 8 hours.
Alternately, store in a dessicator, if an oven is not immediately available.
Dry to constant weight (as in Chapter 18, section 4.1.3).

5\. Determination of C, N and P Flux
5.1.
The quantities of particulate C, N and P in the prescreened trap solutions
are determined using methods described in Chapters 10 and 11. Six replicate
traps are used for C/N determinations and three additional traps for P.
Typically, 1.5-2 liters are used for a single C/N or P measurement. An
equivalent volume of the time-zero sediment trap solution, filtered through
the appropriate filters is used as a C, N or P blank

Addendum - PPO4 protocol (April 7, 2015)

The method used for the analysis of particulate phosphate (PPO4) has been
modified
and applied to samples analyzed November 2011 (HOT 236) to the present. The
previous
protocol was in use over at least the previous 10-year period.

The modified procedure included vortexing of the sample prior to a longer
leaching
time (1 hour versus 30 min) of the GFF filter in 0.15 N HCl at room
temperature.

Both the previous and modified procedures were tested in paired analyses on
samples
collected over one year (12 cruises). The modified procedure resulted in
higher yields
by approximately 50% for water column samples (integrated 0-100 m: old
method 1.00\u00b10.27
mmol P m-2, versus 1.56\u00b10.14 mmol P m-2) and approximately 30% for
P-flux estimated
from sediment trap samples (old method: 0.31\u00b10.07 mg P m-2 d-1 versus
0.40\u00b10.09 mg P m-2 d-1).

Please see the HOT Data Report 2012 for more detail
attribute NC_GLOBAL awards_0_award_nid String 54915
attribute NC_GLOBAL awards_0_award_number String OCE-0926766
attribute NC_GLOBAL awards_0_data_url String http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0926766 (external link)
attribute NC_GLOBAL awards_0_funder_name String NSF Division of Ocean Sciences
attribute NC_GLOBAL awards_0_funding_acronym String NSF OCE
attribute NC_GLOBAL awards_0_funding_source_nid String 355
attribute NC_GLOBAL awards_0_program_manager String David L. Garrison
attribute NC_GLOBAL awards_0_program_manager_nid String 50534
attribute NC_GLOBAL cdm_data_type String Other
attribute NC_GLOBAL comment String version: 2018-04-25

Particle flux data
from monthly HOT cruises to deep-water Station ALOHA
attribute NC_GLOBAL Conventions String COARDS, CF-1.6, ACDD-1.3
attribute NC_GLOBAL creator_email String info at bco-dmo.org
attribute NC_GLOBAL creator_name String BCO-DMO
attribute NC_GLOBAL creator_type String institution
attribute NC_GLOBAL creator_url String https://www.bco-dmo.org/ (external link)
attribute NC_GLOBAL data_source String extract_data_as_tsv version 2.3 19 Dec 2019
attribute NC_GLOBAL date_created String 2018-05-23T15:02:45Z
attribute NC_GLOBAL date_modified String 2019-12-11T14:43:51Z
attribute NC_GLOBAL defaultDataQuery String &amp;time&lt;now
attribute NC_GLOBAL doi String 10.1575/1912/bco-dmo.737393.1
attribute NC_GLOBAL Easternmost_Easting double -158.0
attribute NC_GLOBAL geospatial_lat_max double 22.75
attribute NC_GLOBAL geospatial_lat_min double 22.75
attribute NC_GLOBAL geospatial_lat_units String degrees_north
attribute NC_GLOBAL geospatial_lon_max double -158.0
attribute NC_GLOBAL geospatial_lon_min double -158.0
attribute NC_GLOBAL geospatial_lon_units String degrees_east
attribute NC_GLOBAL geospatial_vertical_max double 500.0
attribute NC_GLOBAL geospatial_vertical_min double 70.0
attribute NC_GLOBAL geospatial_vertical_positive String down
attribute NC_GLOBAL geospatial_vertical_units String m
attribute NC_GLOBAL infoUrl String https://www.bco-dmo.org/dataset/737393 (external link)
attribute NC_GLOBAL institution String BCO-DMO
attribute NC_GLOBAL instruments_0_acronym String Sediment Trap
attribute NC_GLOBAL instruments_0_dataset_instrument_description String sediment trap array (spar buoy, radiotransmitter, strobe light, floats, trap supports, collector tubes)
attribute NC_GLOBAL instruments_0_dataset_instrument_nid String 737470
attribute NC_GLOBAL instruments_0_description String Sediment traps are specially designed containers deployed in the water column for periods of time to collect particles from the water column falling toward the sea floor. In general a sediment trap has a jar at the bottom to collect the sample and a broad funnel-shaped opening at the top with baffles to keep out very large objects and help prevent the funnel from clogging. This designation is used when the specific type of sediment trap was not specified by the contributing investigator.
attribute NC_GLOBAL instruments_0_instrument_external_identifier String https://vocab.nerc.ac.uk/collection/L05/current/33/ (external link)
attribute NC_GLOBAL instruments_0_instrument_name String Sediment Trap
attribute NC_GLOBAL instruments_0_instrument_nid String 518
attribute NC_GLOBAL instruments_0_supplied_name String sediment trap array
attribute NC_GLOBAL instruments_1_acronym String CHN
attribute NC_GLOBAL instruments_1_dataset_instrument_description String PE-2400 Carbon/Nitrogen analyzer with integrator
attribute NC_GLOBAL instruments_1_dataset_instrument_nid String 737472
attribute NC_GLOBAL instruments_1_description String A unit that accurately determines the carbon and nitrogen concentrations of organic compounds typically by detecting and measuring their combustion products (CO2 and NO).
attribute NC_GLOBAL instruments_1_instrument_name String Particulate Organic Carbon/Nitrogen Analyzer
attribute NC_GLOBAL instruments_1_instrument_nid String 654
attribute NC_GLOBAL instruments_1_supplied_name String PE-2400 Carbon/Nitrogen analyzer with integrator
attribute NC_GLOBAL instruments_2_acronym String Spectrophotometer
attribute NC_GLOBAL instruments_2_dataset_instrument_description String spectrophotometer (Perkin-Elmer Lambda 3B) and 1-cm cuvette
attribute NC_GLOBAL instruments_2_dataset_instrument_nid String 737473
attribute NC_GLOBAL instruments_2_description String An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples.
attribute NC_GLOBAL instruments_2_instrument_external_identifier String https://vocab.nerc.ac.uk/collection/L05/current/LAB20/ (external link)
attribute NC_GLOBAL instruments_2_instrument_name String Spectrophotometer
attribute NC_GLOBAL instruments_2_instrument_nid String 707
attribute NC_GLOBAL instruments_2_supplied_name String spectrophotometer and 1-cm cuvette
attribute NC_GLOBAL instruments_3_acronym String Scale
attribute NC_GLOBAL instruments_3_dataset_instrument_description String Cahn electronic microbalance
attribute NC_GLOBAL instruments_3_dataset_instrument_nid String 737471
attribute NC_GLOBAL instruments_3_description String An instrument used to measure weight or mass.
attribute NC_GLOBAL instruments_3_instrument_external_identifier String https://vocab.nerc.ac.uk/collection/L05/current/LAB13/ (external link)
attribute NC_GLOBAL instruments_3_instrument_name String Scale
attribute NC_GLOBAL instruments_3_instrument_nid String 714
attribute NC_GLOBAL instruments_3_supplied_name String Cahn electronic microbalance
attribute NC_GLOBAL keywords String bco, bco-dmo, biological, carbon, Carbon_n, Carbon_sd_diff, chemical, cruise, data, dataset, delta, Delta_13C, Delta_13C_n, Delta_13C_sd_diff, Delta_15N, Delta_15N_n, Delta_15N_sd_diff, depth, diff, dmo, erddap, filename, flux, inorganic, latitude, longitude, management, mass, Mass_n, Mass_sd_diff, nitrogen, Nitrogen_n, Nitrogen_sd_diff, oceanography, office, P_flux_filename, particulate, phosphorus, Phosphorus_n, Phosphorus_sd_diff, pic, PIC_n, PIC_sd_diff, preliminary, silica, Silica_n, Silica_sd_diff, treatment
attribute NC_GLOBAL license String https://www.bco-dmo.org/dataset/737393/license (external link)
attribute NC_GLOBAL metadata_source String https://www.bco-dmo.org/api/dataset/737393 (external link)
attribute NC_GLOBAL Northernmost_Northing double 22.75
attribute NC_GLOBAL param_mapping String {'737393': {'lat': 'flag - latitude', 'Depth': 'flag - depth', 'lon': 'flag - longitude'}}
attribute NC_GLOBAL parameter_source String https://www.bco-dmo.org/mapserver/dataset/737393/parameters (external link)
attribute NC_GLOBAL people_0_affiliation String University of Hawaii at Manoa
attribute NC_GLOBAL people_0_affiliation_acronym String SOEST
attribute NC_GLOBAL people_0_person_name String David M. Karl
attribute NC_GLOBAL people_0_person_nid String 50750
attribute NC_GLOBAL people_0_role String Principal Investigator
attribute NC_GLOBAL people_0_role_type String originator
attribute NC_GLOBAL people_1_affiliation String University of Hawaii at Manoa
attribute NC_GLOBAL people_1_affiliation_acronym String SOEST
attribute NC_GLOBAL people_1_person_name String Lance A Fujieki
attribute NC_GLOBAL people_1_person_nid String 51683
attribute NC_GLOBAL people_1_role String Contact
attribute NC_GLOBAL people_1_role_type String related
attribute NC_GLOBAL people_2_affiliation String Woods Hole Oceanographic Institution
attribute NC_GLOBAL people_2_affiliation_acronym String WHOI BCO-DMO
attribute NC_GLOBAL people_2_person_name String Mathew Biddle
attribute NC_GLOBAL people_2_person_nid String 708682
attribute NC_GLOBAL people_2_role String BCO-DMO Data Manager
attribute NC_GLOBAL people_2_role_type String related
attribute NC_GLOBAL project String HOT
attribute NC_GLOBAL projects_0_acronym String HOT
attribute NC_GLOBAL projects_0_description String Systematic, long-term observations are essential for evaluating natural variability of Earth’s climate and ecosystems and their responses to anthropogenic disturbances.  Since October 1988, the Hawaii Ocean Time-series (HOT) program has investigated temporal dynamics in biology, physics, and chemistry at Stn. ALOHA (22°45' N, 158°W), a deep ocean field site in the oligotrophic North Pacific Subtropical Gyre (NPSG). HOT conducts near monthly ship-based sampling and makes continuous observations from moored instruments to document and study NPSG climate and ecosystem variability over semi-diurnal to decadal time scales. HOT was founded to understand the processes controlling the time-varying fluxes of carbon and associated biogenic elements in the ocean and to document changes in the physical structure of the water column. To achieve these broad objectives, the program has several specific goals:
Quantify time-varying (seasonal to decadal) changes in reservoirs and fluxes of carbon (C) and associated bioelements (nitrogen, oxygen, phosphorus, and silicon).
Identify processes controlling air-sea C exchange, rates of C transformation through the planktonic food web, and fluxes of C into the ocean’s interior.
Develop a climatology of hydrographic and biogeochemical dynamics from which to form a multi-decadal baseline from which to decipher natural and anthropogenic influences on the NPSG ecosystem. 
Provide scientific and logistical support to ancillary programs that benefit from the temporal context, interdisciplinary science, and regular access to the open sea afforded by HOT program occupation of Sta. ALOHA, including projects implementing, testing, and validating new methodologies, models, and transformative ocean sampling technologies.
Over the past 24+ years, time-series research at Station ALOHA has provided an unprecedented view of temporal variability in NPSG climate and ecosystem processes.  Foremost among HOT accomplishments are an increased understanding of the sensitivity of bioelemental cycling to large scale ocean-climate interactions, improved quantification of reservoirs and time varying fluxes of carbon, identification of the importance of the hydrological cycle and its influence on upper ocean biogeochemistry, and the creation of long-term data sets from which the oceanic response to anthropogenic perturbation of elemental cycles may be gauged. 
A defining characteristic of the NPSG is the perennially oligotrophic nature of the upper ocean waters.  This biogeochemically reactive layer of the ocean is where air-sea exchange of climate reactive gases occurs, solar radiation fuels rapid biological transformation of nutrient elements, and diverse assemblages of planktonic organisms comprise the majority of living biomass and sustain productivity.  The prevailing Ekman convergence and weak seasonality in surface light flux, combined with relatively mild subtropical weather and persistent stratification, result in a nutrient depleted upper ocean habitat.  The resulting dearth of bioessential nutrients limits plankton standing stocks and maintains a deep (175 m) euphotic zone.  Despite the oligotrophic state of the NPSG, estimates of net organic matter production at Sta. ALOHA are estimated to range ~1.4 and 4.2 mol C m2 yr1.  Such respectable rates of productivity have highlighted the need to identify processes supplying growth limiting nutrients to the upper ocean.  Over the lifetime of HOT numerous ancillary science projects have leveraged HOT science and infrastructure to examine possible sources of nutrients supporting plankton productivity.  Both physical (mixing, upwelling) and biotic (N2 fixation, vertical migration) processes supply nutrients to the upper ocean in this region, and HOT has been instrumental in demonstrating that these processes are sensitive to variability in ocean climate.
Station ALOHA - site selection and infrastructure
Station ALOHA is a deep water (~4800 m) location approximately 100 km north of the Hawaiian Island of Oahu.  Thus, the region is far enough from land to be free of coastal ocean dynamics and terrestrial inputs, but close enough to a major port (Honolulu) to make relatively short duration (45 m depth), below depths of detection by Earth-orbiting satellites.  The emerging data emphasize the value of in situ measurements for validating remote and autonomous detection of plankton biomass and productivity and demonstrate that detection of potential secular-scale changes in productivity against the backdrop of significant interannual and decadal fluctuations demands a sustained sampling effort.     
Careful long-term measurements at Stn. ALOHA also highlight a well-resolved, though relatively weak, seasonal climatology in upper ocean primary productivity.  Measurements of 14C-primary production document a ~3-fold increase during the summer months (Karl et al., 2012) that coincides with increases in plankton biomass (Landry et al., 2001; Sheridan and Landry, 2004).  Moreover, phytoplankton blooms, often large enough to be detected by ocean color satellites, are a recurrent summertime feature of these waters (White et al., 2007; Dore et al., 2008; Fong et al., 2008). Analyses of ~13-years (1992-2004) of particulate C, N, P, and biogenic Si fluxes collected from bottom-moored deep-ocean (2800 m and 4000 m) sediment traps provide clues to processes underlying these seasonal changes.  Unlike the gradual summertime increase in sinking particle flux observed in the upper ocean (150 m) traps, the deep sea particle flux record depicts a sharply defined summer maximum that accounts for ~20% of the annual POC flux to the deep sea, and appears driven by rapidly sinking diatom biomass (Karl et al., 2012).  Analyses of the 15N isotopic signatures associated with sinking particles at Sta. ALOHA, together with genetic analyses of N2 fixing microorganisms, implicates upper ocean N2 fixation as a major control on the magnitude and efficiency of the biological carbon pump in this ecosystem (Dore et al., 2002; Church et al., 2009; Karl et al., 2012).
Motivating Questions
Science results from HOT continue to raise new, important questions about linkages between ocean climate and biogeochemistry that remain at the core of contemporary oceanography.  Answers have begun to emerge from the existing suite of core program measurements; however, sustained sampling is needed to improve our understanding of contemporary ecosystem behavior and our ability to make informed projections of future changes to this ecosystem. HOT continues to focus on providing answers to some of the questions below:
How sensitive are rates of primary production and organic matter export to short- and long-term climate variability?
What processes regulate nutrient supply to the upper ocean and how sensitive are these processes to climate forcing? 
What processes control the magnitude of air-sea carbon exchange and over what time scales do these processes vary?
Is the strength of the NPSG CO2 sink changing in time?
To what extent does advection (including eddies) contribute to the mixed layer salinity budget over annual to decadal time scales and what are the implications for upper ocean biogeochemistry?
How do variations in plankton community structure influence productivity and material export? 
What processes trigger the formation and demise of phytoplankton blooms in a persistently stratified ocean ecosystem?
References
attribute NC_GLOBAL projects_0_end_date String 2014-12
attribute NC_GLOBAL projects_0_geolocation String North Pacific Subtropical Gyre; 22 deg 45 min N, 158 deg W
attribute NC_GLOBAL projects_0_name String Hawaii Ocean Time-series (HOT): Sustaining ocean ecosystem and climate observations in the North Pacific Subtropical Gyre
attribute NC_GLOBAL projects_0_project_nid String 2101
attribute NC_GLOBAL projects_0_project_website String http://hahana.soest.hawaii.edu/hot/hot_jgofs.html (external link)
attribute NC_GLOBAL projects_0_start_date String 1988-07
attribute NC_GLOBAL publisher_name String Biological and Chemical Oceanographic Data Management Office (BCO-DMO)
attribute NC_GLOBAL publisher_type String institution
attribute NC_GLOBAL sourceUrl String (local files)
attribute NC_GLOBAL Southernmost_Northing double 22.75
attribute NC_GLOBAL standard_name_vocabulary String CF Standard Name Table v55
attribute NC_GLOBAL subsetVariables String longitude,latitude
attribute NC_GLOBAL summary String Particle flux measurements from the Hawaii Ocean Time-Series (HOT). Particle flux was measured at a standard reference depth of 150 m using multiple cylindrical particle interceptor traps deployed on a free-floating array for approximately 60 h during each cruise. Sediment trap design and collection methods are described in Winn et al. (1991). Samples were analyzed for particulate C, N, P & Si. Typically six traps are analyzed for PC and PN, three for PP, and another three traps for PSi.
attribute NC_GLOBAL title String Sediment trap flux measurements from the Hawaii Ocean Time-Series (HOT) project at station ALOHA.
attribute NC_GLOBAL version String 1
attribute NC_GLOBAL Westernmost_Easting double -158.0
attribute NC_GLOBAL xml_source String osprey2erddap.update_xml() v1.3
variable Cruise   short  
attribute Cruise _FillValue short 32767
attribute Cruise actual_range short 2, 287
attribute Cruise bcodmo_name String cruise_id
attribute Cruise description String Cruise Number
attribute Cruise long_name String Cruise
attribute Cruise units String unitless
variable P_flux_filename   String  
attribute P_flux_filename bcodmo_name String file_name
attribute P_flux_filename description String Original filename of the particle flux data from HOT
attribute P_flux_filename long_name String P Flux Filename
attribute P_flux_filename units String unitless
variable longitude   double  
attribute longitude _CoordinateAxisType String Lon
attribute longitude _FillValue double NaN
attribute longitude actual_range double -158.0, -158.0
attribute longitude axis String X
attribute longitude bcodmo_name String longitude
attribute longitude colorBarMaximum double 180.0
attribute longitude colorBarMinimum double -180.0
attribute longitude description String Longitude with East negative
attribute longitude ioos_category String Location
attribute longitude long_name String Longitude
attribute longitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LONX/ (external link)
attribute longitude standard_name String longitude
attribute longitude units String degrees_east
variable latitude   double  
attribute latitude _CoordinateAxisType String Lat
attribute latitude _FillValue double NaN
attribute latitude actual_range double 22.75, 22.75
attribute latitude axis String Y
attribute latitude bcodmo_name String latitude
attribute latitude colorBarMaximum double 90.0
attribute latitude colorBarMinimum double -90.0
attribute latitude description String Latitude with South negative
attribute latitude ioos_category String Location
attribute latitude long_name String Latitude
attribute latitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LATX/ (external link)
attribute latitude standard_name String latitude
attribute latitude units String degrees_north
variable depth   double  
attribute depth _CoordinateAxisType String Height
attribute depth _CoordinateZisPositive String down
attribute depth _FillValue double NaN
attribute depth actual_range double 70.0, 500.0
attribute depth axis String Z
attribute depth bcodmo_name String depth
attribute depth colorBarMaximum double 8000.0
attribute depth colorBarMinimum double -8000.0
attribute depth colorBarPalette String TopographyDepth
attribute depth description String Depth
attribute depth ioos_category String Location
attribute depth long_name String Depth
attribute depth nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/DEPH/ (external link)
attribute depth positive String down
attribute depth standard_name String depth
attribute depth units String m
variable Treatment   String  
attribute Treatment bcodmo_name String treatment
attribute Treatment description String C-Solutions from individual traps combined and replicate subsamples drawn from this solution. I-Individual traps sampled as replicates. W-Swimmers picked out before analyzed.O-Some other (special?) treatment.
attribute Treatment long_name String Treatment
attribute Treatment units String unitless
variable Carbon   float  
attribute Carbon _FillValue float NaN
attribute Carbon actual_range float 3.5, 61.4
attribute Carbon bcodmo_name String C
attribute Carbon description String Carbon
attribute Carbon long_name String Carbon
attribute Carbon units String miligrams per square meter per day (mg/m2/d)
variable Carbon_sd_diff   float  
attribute Carbon_sd_diff _FillValue float NaN
attribute Carbon_sd_diff actual_range float 0.1, 28.6
attribute Carbon_sd_diff bcodmo_name String C
attribute Carbon_sd_diff colorBarMaximum double 50.0
attribute Carbon_sd_diff colorBarMinimum double 0.0
attribute Carbon_sd_diff description String Standard Deviation presented where Carbon_n=3; Difference between replicate presented where Carbon_n=2
attribute Carbon_sd_diff long_name String Carbon Sd Diff
attribute Carbon_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Carbon_n   byte  
attribute Carbon_n _FillValue byte 127
attribute Carbon_n actual_range byte 1, 6
attribute Carbon_n bcodmo_name String replicate
attribute Carbon_n description String Number of replicate samples collected for replicate analysis.
attribute Carbon_n long_name String Carbon N
attribute Carbon_n units String unitless
variable Nitrogen   float  
attribute Nitrogen _FillValue float NaN
attribute Nitrogen actual_range float 0.27, 14.3
attribute Nitrogen bcodmo_name String N
attribute Nitrogen description String Nitrogen
attribute Nitrogen long_name String Nitrogen
attribute Nitrogen units String miligrams per square meter per day (mg/m2/d)
variable Nitrogen_sd_diff   float  
attribute Nitrogen_sd_diff _FillValue float NaN
attribute Nitrogen_sd_diff actual_range float 0.03, 3.84
attribute Nitrogen_sd_diff bcodmo_name String N
attribute Nitrogen_sd_diff colorBarMaximum double 50.0
attribute Nitrogen_sd_diff colorBarMinimum double 0.0
attribute Nitrogen_sd_diff description String Standard Deviation presented where Nitrogen_n=3; Difference between replicate presented where Nitrogen_n=2
attribute Nitrogen_sd_diff long_name String Nitrogen Sd Diff
attribute Nitrogen_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Nitrogen_n   byte  
attribute Nitrogen_n _FillValue byte 127
attribute Nitrogen_n actual_range byte 1, 9
attribute Nitrogen_n bcodmo_name String replicate
attribute Nitrogen_n description String Number of replicate samples collected for replicate analysis.
attribute Nitrogen_n long_name String Nitrogen N
attribute Nitrogen_n units String unitless
variable Phosphorus   float  
attribute Phosphorus _FillValue float NaN
attribute Phosphorus actual_range float 0.008, 1.136
attribute Phosphorus bcodmo_name String PIP
attribute Phosphorus description String Phosphorus
Addendum - PPO4 protocol (April 7 2015) The method used for the analysis of particulate phosphate (PPO4) has been modified and applied to samples analyzed November 2011 (HOT 236) to the present. The previous protocol was in use over at least the previous 10-year period. The modified procedure included vortexing of the sample prior to a longer leaching time (1 hour versus 30 min) of the GFF filter in 0.15 N HCl at room temperature. Both the previous and modified procedures were tested in paired analyses on samples collected over one year (12 cruises). The modified procedure resulted in higher yields by approximately 50% for water column samples (integrated 0-100 m: old method 1.00±0.27 mmol P m-2 versus 1.56±0.14 mmol P m-2) and approximately 30% for P-flux estimated from sediment trap samples (old method: 0.31±0.07 mg P m-2 d-1 versus 0.40±0.09 mg P m-2 d-1). Please see the HOT Data Report 2012 for more detail.
attribute Phosphorus long_name String Phosphorus
attribute Phosphorus units String miligrams per square meter per day (mg/m2/d)
variable Phosphorus_sd_diff   float  
attribute Phosphorus_sd_diff _FillValue float NaN
attribute Phosphorus_sd_diff actual_range float 0.001, 0.366
attribute Phosphorus_sd_diff bcodmo_name String PIP
attribute Phosphorus_sd_diff colorBarMaximum double 50.0
attribute Phosphorus_sd_diff colorBarMinimum double 0.0
attribute Phosphorus_sd_diff description String Standard Deviation presented where Phosphorus_n=3; Difference between replicate presented where Phosphorus_n=2
attribute Phosphorus_sd_diff long_name String Phosphorus Sd Diff
attribute Phosphorus_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Phosphorus_n   byte  
attribute Phosphorus_n _FillValue byte 127
attribute Phosphorus_n actual_range byte 1, 3
attribute Phosphorus_n bcodmo_name String replicate
attribute Phosphorus_n description String Number of replicate samples collected for replicate analysis.
attribute Phosphorus_n long_name String Phosphorus N
attribute Phosphorus_n units String unitless
variable Mass   float  
attribute Mass _FillValue float NaN
attribute Mass actual_range float 8.5, 131.0
attribute Mass bcodmo_name String mass
attribute Mass description String Mass
attribute Mass long_name String Mass
attribute Mass units String miligrams per square meter per day (mg/m2/d)
variable Mass_sd_diff   float  
attribute Mass_sd_diff _FillValue float NaN
attribute Mass_sd_diff actual_range float 0.3, 49.1
attribute Mass_sd_diff bcodmo_name String mass
attribute Mass_sd_diff colorBarMaximum double 50.0
attribute Mass_sd_diff colorBarMinimum double 0.0
attribute Mass_sd_diff description String Standard Deviation presented where Mass_n=3; Difference between replicate presented where Mass_n=2
attribute Mass_sd_diff long_name String Mass Sd Diff
attribute Mass_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Mass_n   byte  
attribute Mass_n _FillValue byte 127
attribute Mass_n actual_range byte 2, 8
attribute Mass_n bcodmo_name String replicate
attribute Mass_n description String Number of replicate samples collected for replicate analysis.
attribute Mass_n long_name String Mass N
attribute Mass_n units String unitless
variable Silica   float  
attribute Silica _FillValue float NaN
attribute Silica actual_range float 0.189, 21.579
attribute Silica bcodmo_name String Si
attribute Silica description String Silica
attribute Silica long_name String Silica
attribute Silica units String miligrams per square meter per day (mg/m2/d)
variable Silica_sd_diff   float  
attribute Silica_sd_diff _FillValue float NaN
attribute Silica_sd_diff actual_range float 0.03, 7.367
attribute Silica_sd_diff bcodmo_name String Si
attribute Silica_sd_diff colorBarMaximum double 50.0
attribute Silica_sd_diff colorBarMinimum double 0.0
attribute Silica_sd_diff description String Standard Deviation presented where Silica_n=3; Difference between replicate presented where Silica_n=2
attribute Silica_sd_diff long_name String Silica Sd Diff
attribute Silica_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Silica_n   byte  
attribute Silica_n _FillValue byte 127
attribute Silica_n actual_range byte 2, 3
attribute Silica_n bcodmo_name String replicate
attribute Silica_n description String Number of replicate samples collected for replicate analysis.
attribute Silica_n long_name String Silica N
attribute Silica_n units String unitless
variable Delta_15N   float  
attribute Delta_15N _FillValue float NaN
attribute Delta_15N actual_range float -1.17, 6.89
attribute Delta_15N bcodmo_name String d15N
attribute Delta_15N description String Delta-15N of PN (permil vs. air-N2)
attribute Delta_15N long_name String Delta 15 N
attribute Delta_15N units String permil vs. air-N2
variable Delta_15N_sd_diff   float  
attribute Delta_15N_sd_diff _FillValue float NaN
attribute Delta_15N_sd_diff actual_range float 0.0, 1.93
attribute Delta_15N_sd_diff bcodmo_name String d15N
attribute Delta_15N_sd_diff colorBarMaximum double 50.0
attribute Delta_15N_sd_diff colorBarMinimum double 0.0
attribute Delta_15N_sd_diff description String Standard Deviation presented where Delta_15N_n=3; Difference between replicate presented where Delta_15N_n=2
attribute Delta_15N_sd_diff long_name String Delta 15 N Sd Diff
attribute Delta_15N_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Delta_15N_n   byte  
attribute Delta_15N_n _FillValue byte 127
attribute Delta_15N_n actual_range byte 1, 6
attribute Delta_15N_n bcodmo_name String replicate
attribute Delta_15N_n description String Number of replicate samples collected for replicate analysis.
attribute Delta_15N_n long_name String Delta 15 N N
attribute Delta_15N_n units String unitless
variable Delta_13C   float  
attribute Delta_13C _FillValue float NaN
attribute Delta_13C actual_range float -27.5, -16.96
attribute Delta_13C bcodmo_name String delta13C
attribute Delta_13C description String Delta-13C of PC (permil vs. VPDB)
attribute Delta_13C long_name String Delta 13 C
attribute Delta_13C nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/D13CMITX/ (external link)
attribute Delta_13C units String permil vs. VPDB
variable Delta_13C_sd_diff   float  
attribute Delta_13C_sd_diff _FillValue float NaN
attribute Delta_13C_sd_diff actual_range float 0.05, 1.94
attribute Delta_13C_sd_diff bcodmo_name String delta13C
attribute Delta_13C_sd_diff colorBarMaximum double 50.0
attribute Delta_13C_sd_diff colorBarMinimum double 0.0
attribute Delta_13C_sd_diff description String Standard Deviation presented where Delta_13C_n=3; Difference between replicate presented where Delta_13C_n=2
attribute Delta_13C_sd_diff long_name String Delta 13 C Sd Diff
attribute Delta_13C_sd_diff nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/D13CMITX/ (external link)
attribute Delta_13C_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable Delta_13C_n   byte  
attribute Delta_13C_n _FillValue byte 127
attribute Delta_13C_n actual_range byte 1, 6
attribute Delta_13C_n bcodmo_name String replicate
attribute Delta_13C_n description String Number of replicate samples collected for replicate analysis.
attribute Delta_13C_n long_name String Delta 13 C N
attribute Delta_13C_n units String unitless
variable PIC   float  
attribute PIC _FillValue float NaN
attribute PIC actual_range float 0.04, 9.63
attribute PIC bcodmo_name String PIC
attribute PIC description String Particulate Inorganic Carbon
attribute PIC long_name String Particulate Inorganic Carbon
attribute PIC units String miligrams per square meter per day (mg/m2/d)
variable PIC_sd_diff   float  
attribute PIC_sd_diff _FillValue float NaN
attribute PIC_sd_diff actual_range float 0.0, 4.56
attribute PIC_sd_diff bcodmo_name String PIC
attribute PIC_sd_diff colorBarMaximum double 50.0
attribute PIC_sd_diff colorBarMinimum double 0.0
attribute PIC_sd_diff description String Standard Deviation presented where PIC_n=3; Difference between replicate presented where PIC_n=2
attribute PIC_sd_diff long_name String PIC Sd Diff
attribute PIC_sd_diff units String miligrams per square meter per day (mg/m2/d)
variable PIC_n   byte  
attribute PIC_n _FillValue byte 127
attribute PIC_n actual_range byte 1, 3
attribute PIC_n bcodmo_name String replicate
attribute PIC_n description String Number of replicate samples collected for replicate analysis.
attribute PIC_n long_name String PIC N
attribute PIC_n units String unitless

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