Rabalais, N., Unknown, Louisiana Coastal Hypoxia Shelfwide Survey, July 1994S.
This is a Point data set. It contains the following vector data types (SDTS terminology):
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Degrees and decimal minutes.
The horizontal datum used is WGS84.
The ellipsoid used is WGS84.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257223563.
| Range of values | |
|---|---|
| Minimum: | 1.41526 |
| Maximum: | 5.65176 |
| Units: | S/m |
| Range of values | |
|---|---|
| Minimum: | 0.6691 |
| Maximum: | 25.6083 |
| Units: | Density sigma-t |
| Range of values | |
|---|---|
| Minimum: | 0.763 |
| Maximum: | 62.614 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 0.154 |
| Maximum: | 4.11 |
| Units: | volts |
Character field, generally numeric equivalent of text value except in 15 cases where ">10.0" indicates fluorometer was maximized.
| Range of values | |
|---|---|
| Minimum: | 0.14584 |
| Maximum: | 8.43785 |
| Units: | mg/L |
| Range of values | |
|---|---|
| Minimum: | 2.2 |
| Maximum: | 119.6 |
| Units: | Percent |
| Range of values | |
|---|---|
| Minimum: | 14.3 |
| Maximum: | 95.5 |
| Units: | Percent |
| Range of values | |
|---|---|
| Minimum: | 7.2065 |
| Maximum: | 36.4319 |
| Units: | ppt |
Character field
| Range of values | |
|---|---|
| Minimum: | 1862 |
| Maximum: | 1915 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 20.3298 |
| Maximum: | 31.1161 |
| Units: | Degrees centigrade |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 63.5 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 0.2 |
| Maximum: | 9.1 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 6.3 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 101.3 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 100.7 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 4.2 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.5 |
| Maximum: | 103.5 |
| Units: | µg-at/L |
Character field
| Range of values | |
|---|---|
| Minimum: | 1858 |
| Maximum: | 1940 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 63.5 |
| Units: | meter |
| Range of values | |
|---|---|
| Minimum: | 0.05 |
| Maximum: | 28.55 |
| Units: | µg/L |
| Range of values | |
|---|---|
| Minimum: | 1.16 |
| Maximum: | 5.77 |
| Units: | FoFa ratio |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 65.4 |
| Units: | µg/L |
Character field
| Range of values | |
|---|---|
| Minimum: | 1858 |
| Maximum: | 1940 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 0.19 |
| Maximum: | 86.67 |
| Units: | µg/L |
| Range of values | |
|---|---|
| Minimum: | 19940724 |
| Maximum: | 19940729 |
| Units: | YYYYMMDD |
| Range of values | |
|---|---|
| Minimum: | 5 |
| Maximum: | 62 |
| Units: | meter |
| Range of values | |
|---|---|
| Minimum: | 28.3915 |
| Maximum: | 29.7065 |
| Units: | Decimal degrees |
| Range of values | |
|---|---|
| Minimum: | -93.417 |
| Maximum: | -89.423 |
| Units: | Decimal degrees |
| Range of values | |
|---|---|
| Minimum: | 0.2 |
| Maximum: | 11 |
| Units: | meter |
Character field
| Range of values | |
|---|---|
| Minimum: | 1858 |
| Maximum: | 1940 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 0:15 |
| Maximum: | 23:52 |
| Units: | HH:mm |
| Range of values | |
|---|---|
| Minimum: | 1.7431 |
| Maximum: | 33.7197 |
| Units: | ppt |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 0 |
| Units: | meters |
Character field.
Character field.
| Range of values | |
|---|---|
| Minimum: | 1858 |
| Maximum: | 1940 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 5.6 |
| Maximum: | 38 |
| Units: | mg/L |
| Range of values | |
|---|---|
| Minimum: | 4.07 |
| Maximum: | 26.04 |
| Units: | Density sigma-t |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 63.5 |
| Units: | meters |
| Range of values | |
|---|---|
| Minimum: | 0.03 |
| Maximum: | 9.43 |
| Units: | mg/L |
| Range of values | |
|---|---|
| Minimum: | 0.5 |
| Maximum: | 131.7 |
| Units: | percentage |
| Range of values | |
|---|---|
| Minimum: | 7.49 |
| Maximum: | 8.63 |
| Units: | pH units |
| Range of values | |
|---|---|
| Minimum: | 11 |
| Maximum: | 38.1 |
| Units: | ppt |
| Range of values | |
|---|---|
| Minimum: | 18.6 |
| Maximum: | 57.1 |
| Units: | mS/cm |
Character field.
| Range of values | |
|---|---|
| Minimum: | 1862 |
| Maximum: | 1940 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 20.43 |
| Maximum: | 30.62 |
| Units: | Degrees Centigrade. |
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Tom Oswald
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Baton Rouge, LA 70803
225 388-6700 (voice)
Unknown
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Turner Designs Inc.
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Sunnyvale, CA 94085
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Sea-Bird Electronics, Inc.
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Bellevue, WA 98005
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425 643-9866 (voice)
seabird@seabird.com
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Sea-Bird Electronics, Inc.
1808 136th Place NE
Bellevue, WA 98005
USA
425 643-9866 (voice)
seabird@seabird.com
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Sea-Bird Electronics, Inc.
1808 136th Place NE
Bellevue, WA 98005
USA
425 643-9866 (voice)
seabird@seabird.com
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Sea-Bird Electronics, Inc.
1808 136th Place NE
Bellevue, WA 98005
USA
425 643-9866 (voice)
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Rabalais, N.N., Turner, R.E. and Wiseman Jr, W.J. Funding: Funds for the research were provided by the National Oceanographic and Atmospheric Administration, Nutrient Enhanced Coastal Ocean Productivity (NECOP) program.
Nancy N. Rabalais
Louisiana Universities Marine Consortium
Louisiana Universities Marine Consortium 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown
The physical, biological and chemical data collected are part of a long-term coastal Louisiana dataset. The goal is to understand physical and biological processes that contribute to the causes of hypoxia and use the data to support environmental models for use by resource managers.
Water for chlorophyll analysis (50 - 100 ml) is filtered on board ship through GF/F (0.7 micron) filters, which are then fixed in 5 ml of DMSO/90% acetone (40/60) solution, allowed to extract for at least one hour in the dark, then measured pre- and post-acidification on a Turner Model 10 fluorometer.
Field station locations: Stations were occupied along 12 generally North-South transects across the Louisiana coastal shelf. Station depths ranged from 5 to 63 meters. The objective was to delimit and describe the area of midsummer bottom dissolved oxygen less than 2 (mg/L). Due to limitations of equipment, time and funding, this was not always possible. Northern end stations of transects were chosen based on the survey vessel's minimum depth limits for each longitude. The Northern extent of hypoxia was not reached on three transects. Optimally, one or two stations South of the Southern most station with bottom dissolved oxygen less than 2 (mg/L) were sampled. The limit of hypoxia on the Southern end of transects G and I were not reached.
Care was taken that the collector's hands were clean and avoided touching the water. Gloves were worn when three replicate sample vials and caps were triple rinsed with sample before vial filling and closing. Samples were not filtered. The sample vials were frozen for later analysis in the laboratory.
Nitrogen and phosphorus were analyzed according to methods described in EPA publication EPA 600/4-79-020 (1979), method 350.1 for ammonia-N, method 353.2 for nitrate/nitrite-N, and method 365.1 for phosphate-P. Silicate was analyzed according to Technicon Industrial method 186-72 W/B (1977).
CTD data were post processed using Seasoft version 4.201. All scans were processed without averaging or interpolation with a bin size of one scan. In order to improve alignment between oxygen sensor values and other CTD sensor values, the Seasoft module ALIGNCTD was used to determine which advance best compensated for the delay in oxygen sensor response time. When Seabird data were processed, dissolved oxygen was advanced relative to temperature and conductivity values: + 4.7 seconds.
Data values reported are from downcasts. Downcast scans selected for each CTD station are chosen to illustrate: 1) data values as near to the surface as possible, 2) data values at whole meter increments, and 3) data values as close to the bottom as the CTD was lowered. In certain cases where data values of a parameter changed significantly between whole meter increments, 0.1- or 0.2-meter scans were selected.
Water (approximately 300 to 500 ml) was filtered on board ship through pre-weighed GF/F filters, rinsed with distilled water. The filters were placed in Petri dishes and frozen for later analysis.
Suspended sediment filters were dried 24 hours at 40 - 60 degrees centigrade for 24 hours. Filters were weighed. Total suspended sediments was derived from volume filtered, pre-weight and post weight values.
Water for chlorophyll, nutrient analyses, Autosal salinity and suspended sediments was collected from the surface by twice-rinsed bucket, from mid-water in 5-l Niskin bottles on the Seabird CTD/rosette system and from bottom in a 30-l bottom tripping Niskin bottle secured in a frame with the Hydrolab Surveyor 3.
Depth values of 0 indicate a bucket sample collected from the surface of the water. Deepest depths of water samples were from the bottom-tripping Niskin and correspond to the deepest depth recorded from the Hydrolab. Other depths indicate the p-sensor reading for 5-l Niskin bottles on the Seabird rosette. The Seabird p-sensor was located approx. 1 meter below the mid-point of the 5-l Niskin. Bottom 5-l Niskins on the rosette were used to collect “bottom” water samples at stations A7, A6, B1, B2, B6, B8, C7, C6B, C4, D1, E2, E2A and F3.
During the beginning of the survey, Hydrolab data were obtained for the lowest 2 m of the water column, the upper 1 m of the water column, and as close to the surface as possible. When the Seabird CTD failed, the Hydrolab was used to sample intermediate depths in approximately whole meter increments.
At the beginning of each hydrocast the entire CTD/Rosette package was soaked while submerged 0.5m to 1.0m below the surface until pump flow and oxygen values observed via the Sea-Bird deck unit indicated the system was operating correctly.
In order to minimize the effect of delays in oxygen sensor response time caused by temperature, sensor condition and plumbing configuration, the CTD package was lowered as close to dead slow as possible. The sensor packages were located below the Niskin bottles and rosette.
At stations where the watch chief deemed the structure of the oxygen profile contains features useful in post-processing the oxygen data (AlignCTD), the CTD package was raised at the same speed it was lowered. At all other stations, the upcast is rapid in order to save time.
S794Hydrolab: The dissolved oxygen sensor of the Hydrolab Surveyor 3 was pre- and post-calibrated using air saturated water concentrations and barometric pressure from a laboratory grade barometer. Conductivity and pH were pre- and post-calibrated with the appropriate solutions.
S794Nutrient: Nutrient analyses were conducted by Tom Oswald under the supervision of R. E. Turner.
S794Pigment: The Turner Designs model 10 fluorometer was calibrated for chlorophyll a against a chemical supply house chlorophyll a standard measured on a spectrophotometer yearly (or more frequently if needed). During the cruise, the Fluorometer was blanked and calibrated daily in accordance with Turner Designs recommended procedures. Chlorophyll concentrations were supervised and quality controlled by Nancy Rabalais.
S794Seabird: Sea-Bird factory calibrated conductivity and temperature sensors were maintained and serviced in accordance with to Sea-Bird recommended procedures. The Sea Tech fluorometer and transmissometer were maintained and serviced in accordance with to Sea Tech recommended procedures. Sea-Bird dissolved oxygen sensor was maintained and serviced in accordance with to Sea-Bird recommended procedures.
Oxygen concentration determinations, upper and lower end, were made prior to the cruise by the LUMCON CTD technician and entered into the SeaSoft configuration file. Winkler oxygen titrations were conducted during the cruise. A regression equation developed from Winkler titrations gave a strong, good relationship. A correction of the SeaBird oxygen data was not necessary.
Data reductions from the SeaBird were generated by Ben Cole and quality controlled by Nancy Rabalais.
S794Stns: Position coordinates were logged from RV Pelican’s Loran C/GPS. Station depths were logged from the ship’s fathometer.
S794SalSed: Suspended sediment concentrations were supervised and quality controlled by Nancy Rabalais. Salinity determinations were made with a Guildine Autosal maintained by the LSU Coastal Studies shop.
N. Rabalais performed an additional procedure in quality-control/quality-assurance by evaluating relationships between the data in S794Hydrolab, S794Nutrient, S794Pigment, S794SalSed, S794Seabird and S794Stns.
Station positions were logged from RV Pelican's NorthStar LORAN C/GPS at the beginning of sampling operations. GPS when it was available, LORAN when GPS was not available. Manufacturer's LORAN accuracy claim is 30 meters 90% of the time. Manufacturer's GPS accuracy claim is 100 meters 95% of the time. Wind, currents and tidal forces may have moved the ships from the beginning positions.
Unknown.
Station fathometer, Seabird and Hydrolab CTD maximum depths were occasionally inconsistent. This may have been due to sensor calibration. A more likely cause was ship's movement between the times when the values were recorded.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- 1. Dataset credit required. 2. Experience with similar datasets has shown that when data are plotted or used in further analysis, outlying values may occasionally be discovered. Please report any possible problems with the data to N. Rabalais.
Nancy N. Rabalais
Louisiana Universities Marine Consortium
Louisiana Universities Marine Consortium 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown
I, the data requestor, agree to credit the data originators in any publications, reports or presentations generated from this data. I also accept that although these data have been processed successfully on a computer system at the Louisiana Universities Marine Consortium, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. I recognize that these data are best acquired from the originator and not from a secondary source. I recognize that careful attention must be paid to the contents of the metadata file associated with these data. I will not hold Louisiana Universities Marine Consortium liable for improper or incorrect use of the data described and/or contained herein. This disclaimer applies both to individual use of the data and aggregate use with other data.
| Data format: | MDB (version 9) Size: 0.62 |
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Ben Cole
Louisiana Universities Marine Consortium
LUMCON 8124 Hwy 24
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown