Metadata Report for BODC Series Reference Number 1336538

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles and Lever Action bottles have a capacity between 1.7 and 30 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

Dissolved nutrient data series measured on RV Prince Madog cruise PD06_07

Data Originator

David Hydes, National Oceanographic Centre, Southampton (NOCS)

Content of data series

Originator's Protocol

Samples for nutrient analyses were collected during POL Coastal Observatory cruise 43 in Liverpool Bay, on 16 April 2007 and between 18 - 20 April 2007. The samples were collected from water bottle rosette sampling systems mounted on the lowered CTD. Samples were collected near-surface and near-bed from a total of 36 CTD casts. The samples were stored unfiltered in the dark at-18°C, ready for analysis back at NOC, Southampton.

Concentrations of nutrients were determined using a Burkard segmented flow "AAII" type colorimetric auto-analyser coupled to a digital-analysis microstream data capture and reduction system (Hydes et al., 2004).

BODC Processing

The nutrient data were supplied to BODC as an Excel spreadsheet. This was converted to an ASCII format file for loading into the BODC archive. Methodology and units were checked against information held in the BODC parameter dictionary and an appropriate parameter code was attributed to each variable. The file's data and metadata fields were then checked prior to loading into a database.

No record was kept in either the log or the CTD bottle files of which rosette bottles were used in collection of the nutrient samples. Bottles were fired on the up-cast, with bottles at the sea-bed being triggered first.

Normally, a minimum of two bottles were fired at the sea-bed. The first bottle fired in the sequence was consistently used for independent temperature and salinity samples and no nutrient samples were taken from it. Additionally, a further one or two bottles were triggered (firing sequence numbers two and three), depending on the requirements at the station. As there were always at least two bottles fired and the water from the first bottle was reserved, the bottom nutrient samples were therefore assigned to the bottle identifiers at sequence number two. However, for casts C056 and C062 - C066, only one bottle was fired at the bed so the bottle nutrient samples for these casts were assigned to the bottle identifiers at sequence position one.

With respect to the surface nutrients, the decision was made to assign the nutrient data to the first bottle triggered at the surface. For the majority of the casts, this meant the third bottle triggered on the rosette at each cast. For casts C056 and C062 - C066 however, one bottle only had been fired at the sea-bed so the first surface bottle fired was number two in the sequence. For casts C051 - C055, C075, C079 and C080, three near-bed bottles were fired first so the surface nutrient data for these casts were assigned to the bottle identifiers at sequence position four.

The data were loaded into the database under the Oracle Relational Database Management System by matching the sample's station identifier and depth with the information already held in the database for this cruise. The data were successfully loaded without further modification.

Comments

The values supplied for combined nitrate and nitrite concentration by the Data Originator were negative at the bed for C061 and at the surface and bed for casts C062 and C063. The supplied values have been replaced with a value of zero and the entries have been flagged '<' as being below the level of detection.

The value supplied for phosphate concentration by the Data Originator was negative at the surface for cast C084. The supplied value has been replaced with a value of zero and the entry flagged '<' as being below the level of detection.

References

Hydes, DJ., Gowen, RJ., Holliday, NP., Shammon, T., Mills, D (2004) External and internal control of winter concentrations of nutrients (N, P, Si) in north-west European shelf seas, Estuarine, Coastal and Shelf Science, 59(1), 151-161

Conditions of Use

The Data Originator must be informed that the supply has occurred.

Due acknowledgement of the Originator and the Originator's Institute is made by the receiver in any product using the data.

No commercial gain ensues from usage of the data.

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters within a data cycle:

Project Information

Oceans 2025 Theme 3, Work Package 3.3: Bottom Boundary Layer, Optics and Suspended Sediments Processes

This Work Package (WP) is a combination of Work Package 3.3 and 3.4 as proposed in the original Oceans 2025 proposal. It continues and expands the research undertaken in the Proudman Oceanographic Laboratory Dee Experiment project.

Sediment transport process models underpin scientific ability to predict the entrainment of sediments into the water column and the transport of sediments for forecasting seabed and coastal morphodynamic evolution. The difficulty in achieving accurate process models lies with the complex inter-dependence of sediment processes in the bottom boundary layer. Near the bed, the fundamentals of sediment transport are governed by interactions between the sediment transport triad; the bed, the hydrodynamics and the mobile sediments. These three components interrelate, being mutually interactive and interdependent.

POL aim to use a combination of high-frequency underwater acoustics and laser optical measurements to make co-located simultaneous measurements of the triad. These measurements provide an observational framework capable of assessing and advancing the latest sediment transport models available. These measurements will be made in a range of environments, with the objective of achieving significant advances in understanding and modelling capability in coastal sediment transport. POL will also address the dynamics of suspended sediment behaviour in the context of sediment supply to the coastal zone from estuaries, and of coastal water column optical properties. Ths will allow improvement of the modelling accuracy of coastal suspended sediment transport and enable development of a new description of sediment suspension and water opacity that will improve simulation of coastal primary productivity.

The specific objectives are:

• Assess process-based models over different sediment types, cohesive to non-cohesive
• Investigate intra-wave and turbulence processes over flat and rippled beds to improve process based sediment transport models; parameterisation of the process modelling output for input into large-scale area models
• Advance the description and parameterisation of the impact benthic biota has on sediment transport processes (jointly with the Plymouth Marine Laboratory (PML))
• Acquire new knowledge of the dynamics of sediment flocculation and its impact on suspended particulate material (SPM) in shelf seas and estuaries
• Provide preliminary formulations for aggregation-disaggregation and test these formulations using shelf sea models of the Eastern Irish Sea
• Develop understanding of the processes that affect the sediment fluxes between estuaries and the adjacent shelf sea.
• Derive and apply formulations of the effects of SPM on optical attenuation and absorption and assess their potential impact on primary productivity using existing models

Fieldwork

The study site chosen by POL for this research was the Dee Estuary, Liverpool Bay. POL performed fieldwork in the Hilbre Channel on the eastern side of the Estuary and the Welsh Channel on the western exit of the Estuary, with emphasis placed on two repeat stations, HC and WC. The fieldwork under Work Package 3.3 commenced in April 2007 and has been summarised below:

More detailed information on this Work Package is available at pages 8 - 9 and 9-10 of the official Oceans 2025 Theme 3 document: Oceans 2025 Theme 3

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Data Activity

BODC Sample Metadata Report for PD06_07_CTD_C079

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

No Fixed Station Information held for the Series

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: