Filter Pad absorption measurements of suspended particulate matter - data from the BROKE-West voyage of the Aurora Australis, 2006
Particulates in the water were concentrated onto 25mm glass fibre filters.
Light transmission and reflection through the filters was measured using a spectrophotometer to yield spectral absorption coefficients.
Data Acquisition:
Water samples were taken from Niskin bottles mounted on the CTD rosette. Two or three depths were selected at each station, using the CTD fluorometer profile to identify the depth of maximum fluorescence and below the fluorescence maximum. One sample was always taken at 10m, provided water was available, as a reference depth for comparisons with satellite data (remote sensing international standard). Water sampling was carried out after other groups, leading to a considerable time delay of between half an hour and 3 hours, during which particulates are likely to have sedimented within the Niskin bottle, and algae photoadapted to the dark. In order to minimise problems of sedimentation, as large a sample as practical was taken. Often so little water remained in the Niskin bottle that the entire remnant was taken. Where less than one litre remained, leftover sample water was taken from the HPLC group. Water samples were filtered through 25mm diameter GF/F filters under a low vacuum (less than 5mmHg), in the dark. Filters were stored in tissue capsules in liquid nitrogen and transported to the lab for analysis after the cruise. Three water samples were filtered through GF/F filters under gravity, with 2 30ml pre-rinses to remove organic substances from the filter, and brought to the laboratory for further filtration through 0.2micron membrane filters.
Filters were analysed in batches of 3 to 7, with all depths at each station being analysed within the same batch to ensure comparability. Filters were removed one batch at a time and place on ice in the dark. Once defrosted, the filters were placed upon a drop of filtered seawater in a clean petri dish and returned to cold, dark conditions. One by one, the filters were placed on a clean glass plate and scanned from 200 to 900nm in a spectrophotometer equipped with an integrating sphere. A fresh baseline was taken with each new batch using 2 blank filters from the same batch as the sample filters, soaked in filtered seawater. After scanning, the filters were placed on a filtration manifold, soaked in methanol for between 1 and 2 hours to extract pigments, and rinsed with filtered seawater. They were then scanned again against blanks soaked in methanol and rinsed in filtered seawater.
Data Processing:
The initial scan of total particulate matter, ap, and the second scan of non-pigmented particles, anp, were corrected for baseline wandering by setting the near-infrared absorption to zero.
This technique requires correction for enhanced scattering within the filter, which has been reported to vary with species. One dilution series was carried out at station 118 to allow calculation of the correction (beta-factor). Since it is debatable whether this factor will be applicable to all samples, no correction has been applied to the dataset. Potential users should contact JSchwarz for advice on this matter when using the data quantitatively.
Not yet complete:
Comparison of the beta-factor calculated for station 118 with the literature values.
Comparison of phytoplankton populations from station 118 with those found at other stations to evaluate the applicability of the beta-factor.
Dataset Format:
Two files: phyto_absorp_brokew.txt and phyto_absorp_brokew_2.txt: covering stations 4 to 90 and 91 to 118, respectively. Note that not every station was sampled.
File format: Matlab-readable ascii text with 3 'header' lines:
Row 1: col.1=-999, col.2 to end = ctd number
Row 2: col.1=-999, col.2 to end = sample depth in metres
Row 3: col.1=-999, col.2 to end = 1 for total absorption by particulates, 2 for absorption by non-pigmented particles
Row 4 to end: col.1=wavelength in nanometres, col.2 to end = absorption coefficient corresponding to station, depth and type given in rows 1 to 3 of the same column.
This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
Simple
Identification info
- Alternate title
- Filter Pad absorption measurements of suspended particulate matter - data from the BROKE-West voyage of the Aurora Australis, 2006
- Date (Publication)
- 2010-08-27
- Edition
- 1
- Citation identifier
-
Dataset DOI
- Title
- Information and documentation - Digital object identifier system
- Date (Publication)
- 2012-04-23
- Citation identifier
- ISO 26324:2012
- Citation identifier
- doi:10.4225/15/598d150b8150c
Originator
Publisher
Principal investigator
Collaborator
Collaborator
- Name
- CAASM Metadata
- Status
- Completed
Custodian
- Topic category
-
- Oceans
Extent
Extent
- Description
- Temporal Coverage
Temporal extent
- TimePeriod
- 2006-01-09 2006-02-28
Extent
- Description
- Vertical Extent - Depth
Vertical element
- Minimum value
- 10
- Maximum value
- 101
- Identifier
- urn:x-ogc:def:cs:EPSG:6498
- Name
- Vertical CS. Axis: depth (D). Orientation: down. UoM: m.
- Identifier
- urn:x-ogc:def:axis:EPSG:113
- Name
- depth
- NASA/GCMD Earth Science Keywords
-
- EARTH SCIENCE > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY > WATER DEPTH
- EARTH SCIENCE > OCEANS > MARINE SEDIMENTS > SEDIMENTATION
- EARTH SCIENCE > OCEANS > OCEAN OPTICS > ABSORPTION
- EARTH SCIENCE > OCEANS > OCEAN OPTICS > FLUORESCENCE
- EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > PLANTS > MICROALGAE
- EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > PLANTS
- EARTH SCIENCE > BIOSPHERE > ECOSYSTEMS > AQUATIC ECOSYSTEMS > PLANKTON > PHYTOPLANKTON
- Keywords
-
- filter pad absorption
- particulates
- niskin water bottles
- phytoplankton
- NASA/GCMD Earth Science Keywords
-
- CTD > Conductivity, Temperature, Depth
- NISKIN BOTTLES
- WATER BOTTLES
- NASA/GCMD Earth Science Keywords
-
- R/V AA > R/V Aurora Australis
- SHIPS
- NASA/GCMD Earth Science Keywords
-
- AMD/AU
- CEOS
- AMD
- ACE/CRC
- NASA/GCMD Earth Science Keywords
-
- OCEAN > SOUTHERN OCEAN
- CONTINENT > ANTARCTICA
- GEOGRAPHIC REGION > POLAR
Resource constraints
- Use limitation
- This metadata record is publicly available.
Resource constraints
- Access constraints
- licence
- Other constraints
- These data are publicly available from the provided URL.
Resource constraints
- File type
- Portable Network Graphic
- Title
- Attribution 4.0 International (CC BY 4.0)
- Website
-
https://creativecommons.org/licenses/by/4.0/legalcode
Legal code for Creative Commons by Attribution 4.0 International license
- Use constraints
- licence
- Other constraints
- This data set conforms to the CCBY Attribution License (http://creativecommons.org/licenses/by/4.0/). Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=BROKE-West_particulates when using these data.
- Language
- English
- Character encoding
- UTF8
Distribution Information
Distributor
Distributor
Distributor
- Fees
- free
- Planned available datetime
- 2010-08-27T00:00:00
- Units of distribution
- kb
- Transfer size
- 300
- Distribution format
-
- text
- OnLine resource
-
GET DATA
Download point for the data
- OnLine resource
-
PROJECT HOME PAGE
Public information for ASAC project 2655
- OnLine resource
-
PROJECT HOME PAGE
Public information for ASAC project 2679
- OnLine resource
-
VIEW RELATED INFORMATION
Citation reference for this metadata record and dataset
Resource lineage
- Statement
- All data are usable. However, sampling was not ideal owing to a considerable delay between collection of water samples in the Niskin bottles and subsampling for optical measurements: sedimentation of the sample in the Niskin bottle and photoadaptation by the algae almost certainly occurred to varying extents at each station. Water samples were taken from each CTD cast at between 1 and 3 depths per station.
- Hierarchy level
- Dataset
- Maintenance and update frequency
- As needed
- Maintenance note
- 2010-08-27 - record updated by Dave Connell to publicly release the data. 2012-06-21 - record updated by Dave Connell to add a parent DIF. 2017-08-11 - record updated by Dave Connell - basic updates.
Metadata
- Metadata identifier
- string/BROKE-West_particulates
- Language
- English
- Character encoding
- UTF8
Author
Sponsor
Owner
- Title
- Parent Metadata Record
- Citation identifier
- BROKE-West
Type of resource
- Resource scope
- Dataset
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Citation identifier
- bd0e43d1-19b0-4127-ac92-7b06e37d9db6
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Date (Last Revision)
- 2015-11-29T19:38:32
Identifier
- Description
- metadata.extraction_date
Alternative metadata reference
- Title
- gov.nasa.gsfc.gcmd
- Citation identifier
- 8.6
- Metadata linkage
-
http://data.aad.gov.au/metadata/records/BROKE-West_particulates
Point of truth for the metadata record
- Date info (Creation)
- 2006-05-29T00:00:00
- Date info (Last Update)
- 2017-08-11
Metadata standard
- Title
- ISO 19115-3
- Edition
- 2014
- Other citation details
- Version 1
- Title
- DIF to ISO 19115-1 Profile