Rabalais, N., Unknown, Louisiana Hypoxia Surveys 1999.
This is a Vector 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: | 19990106 |
| Maximum: | 19991207 |
| Range of values | |
|---|---|
| Minimum: | 7.93 |
| Maximum: | 25.09 |
| Units: | Density sigma-t |
| Range of values | |
|---|---|
| Minimum: | 0.0 |
| Maximum: | 63.2 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 0.04 |
| Maximum: | 16.93 |
| Units: | mg/L |
| Range of values | |
|---|---|
| Minimum: | 0.7 |
| Maximum: | 194.4 |
| Units: | Percent |
| Range of values | |
|---|---|
| Minimum: | 7.5 |
| Maximum: | 8.76 |
| Units: | pH units |
| Range of values | |
|---|---|
| Minimum: | 16.2 |
| Maximum: | 36.5 |
| Units: | psu |
| Range of values | |
|---|---|
| Minimum: | 26.6 |
| Maximum: | 55 |
| Units: | mS/cm |
Character field
| Range of values | |
|---|---|
| Minimum: | 7 |
| Maximum: | 365 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 12.49 |
| Maximum: | 32.41 |
| Units: | Degrees centigrade |
| Range of values | |
|---|---|
| Minimum: | 00:06:28 |
| Maximum: | 23:58:16 |
| Units: | HH:mm:ss |
| Range of values | |
|---|---|
| Minimum: | 19990106 |
| Maximum: | 19991207 |
| Range of values | |
|---|---|
| Minimum: | 28.3921 |
| Maximum: | 29.7052 |
| Units: | Decimal degrees |
| Range of values | |
|---|---|
| Minimum: | -93.6539 |
| Maximum: | -89.414 |
| Units: | Decimal degrees |
| Range of values | |
|---|---|
| Minimum: | 2.38 |
| Maximum: | 35.67 |
| Units: | PSU |
| Range of values | |
|---|---|
| Minimum: | 1.62 |
| Maximum: | 60 |
| Units: | mg/L |
Character field
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 0:11:21 |
| Maximum: | 23:50:05 |
| Units: | Hours:minutes:seconds |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 63.2 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 45 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 12.6 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.2 |
| Maximum: | 117 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 116 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.1 |
| Maximum: | 6.5 |
| Units: | µg-at/L |
| Range of values | |
|---|---|
| Minimum: | 0.3 |
| Maximum: | 120.4 |
| Units: | µg-at/L |
Character field
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 221 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 19990106 |
| Maximum: | 19991207 |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 63.2 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 54.88 |
| Units: | µg/L |
| Range of values | |
|---|---|
| Minimum: | 0.46 |
| Maximum: | 2.06 |
| Units: | Fo/Fa ratio |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 151.8 |
| Units: | µg/L |
Character field
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 0.39 |
| Maximum: | 151.8 |
| Units: | µg/L |
| Range of values | |
|---|---|
| Minimum: | 0 |
| Maximum: | 30.1 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 2.07 |
| Maximum: | 36.315 |
| Units: | psu |
Character field
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 2.618123 |
| Maximum: | 5.957732 |
| Units: | S/m |
| Range of values | |
|---|---|
| Minimum: | 0.328 |
| Maximum: | 61.584 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | -0.01019 |
| Maximum: | 7.285 |
| Units: | Voltage |
| Range of values | |
|---|---|
| Minimum: | 0.3346 |
| Maximum: | 30 |
| Units: | Voltage |
| Range of values | |
|---|---|
| Minimum: | -0.00886 |
| Maximum: | 14.55184 |
| Units: | mg/L |
| Range of values | |
|---|---|
| Minimum: | -0.1302 |
| Maximum: | 191.5108 |
| Units: | Percent |
| Range of values | |
|---|---|
| Minimum: | 16.2414 |
| Maximum: | 36.2044 |
| Units: | psu |
| Range of values | |
|---|---|
| Minimum: | 7.7476 |
| Maximum: | 25.2665 |
| Units: | sigma-t |
Character field
| Range of values | |
|---|---|
| Minimum: | 7 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 12.0932 |
| Maximum: | 33.1086 |
| Units: | Degrees centigrade |
| Range of values | |
|---|---|
| Minimum: | 1.8445 |
| Maximum: | 13.7357 |
| Units: | Voltage |
| Range of values | |
|---|---|
| Minimum: | 0.13 |
| Maximum: | 102.39 |
| Units: | Percent |
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 5 |
| Units: | Feet |
| Range of values | |
|---|---|
| Minimum: | 19990106 |
| Maximum: | 19991207 |
| Range of values | |
|---|---|
| Minimum: | 4.6 |
| Maximum: | 61.8 |
| Units: | Meters |
| Range of values | |
|---|---|
| Minimum: | 28.3915 |
| Maximum: | 29.706 |
| Units: | Decimal degrees. |
| Range of values | |
|---|---|
| Minimum: | -93.6535 |
| Maximum: | -89.4758 |
| Units: | Decimal degrees. |
| Range of values | |
|---|---|
| Minimum: | 0.2 |
| Maximum: | 16 |
| Units: | meters |
Character field
| Range of values | |
|---|---|
| Minimum: | 2 |
| Maximum: | 356 |
| Units: | Integer |
| Range of values | |
|---|---|
| Minimum: | 00:06:28 |
| Maximum: | 23:53:27 |
| Units: | HH:mm:ss |
| Range of values | |
|---|---|
| Minimum: | 00:15 |
| Maximum: | 23:55 |
| Units: | HH:mm |
Rabalais, N.N., Turner, R.E. and Wiseman, Jr., W.J. Funding: Funds for the research were provided by the National Oceanic and Atmospheric Administration, Coastal Ocean Program, Grant Nos. NA86RG0341 and NA960P0112. Funds for rental of the R/V PELICAN for monthly transect C cruises were provided by National Science Foundation Grant No. OCE-9818985 to Q. Dortch, Louisiana Universities Marine Consortium. The PELICAN was supported by the NOAA grants for the summer shelfwide cruise.
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.
The SeaBird CTD number of scans to average in the deck unit was set to one. 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 contained 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.
Deployment: The Hydrolab CTD was attached by chain to a lead weight. The weight was lowered to the bottom by hydrowire. With the weight on the bottom, the Hydrolab sonde was positioned just above the bottom. When the oxygen sensor stabilized, a data record of all the sensor values was stored electronically. The sonde was raised in approximately 1.0-meter increments, after D.O. sensor stabilization, data records were stored. When the Hydrolab was raised a depth of two to three meters from the surface, The sonde was raised, and records stored, in approximately 0.5-meter increments until finally a record was stored with the sonde submerged but as close as possible to the surface.
Deployment: Due to limitations of time and funding, mid-water depths were generally not sampled with the Hydrolab CTD during the shelfwide cruise.
The Hydrolab CTD was attached by chain to a lead weight. The weight was lowered to the bottom by hydrowire. With the weight on the bottom, the Hydrolab sonde was positioned just above the bottom. When the oxygen sensor stabilized, a data record of all the sensor values was stored electronically. The sonde was raised in approximately 0.5-meter increments, after D.O. sensor stabilization, data records were stored. After storing data for the few meters closest to the bottom, the Hydrolab was raised to two to three meters from the surface and a data record was saved. The sonde was raised, and records stored, in approximately 0.5-meter increments until finally a record was stored with the sonde submerged but as close as possible to the surface.
Water for chlorophyll analysis (30 - 100 ml) was filtered on board ship through GF/F (0.7 micron) filters, which were then fixed in 5 ml of DMSO/90% acetone (40/60) solution, allowed to extract for at least two hours in the dark, then measured pre- and post-acidification on a Turner Model 10 fluorometer. Beginning in June 1999, a Turner Model 10 AU was used to measure the samples.
Water was collected in an acid-washed, triple-rinsed 500ml Nalgene jar from a twice-rinsed bucket of surface water. The jar lid was secured tightly to minimize evaporation.
C transect lies South and East of Terrebonne Bay. Nine cross-shelf stations on C transect were sampled monthly. Additional water-column hydrology measurements were made at station C6B when other research missions provided opportunities at that location.
During the July shelfwide cruise, stations were occupied along 14 generally North-South transects across the Louisiana coastal shelf. Station depths ranged from 4.6 to 61.8 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 nine 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 ends of all transects, except transect J, was reached. The limit of hypoxia was not reached at station M3 on the western end of the survey. The limit of hypoxia was not reached at stations A'1, A'2 and A'3 on the eastern end of the survey.
Care was taken that the collector's hands were clean and avoided touching the sample 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.
Water (approximately 300 to 1000 ml) collected for suspended sediment samples 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.
Water for chlorophyll, nutrient analyses and PortaSal salinity 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 5-l bottom tripping Niskin deployed on the Hydrolab hydrowire.
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.
Water for Suspended Sediment samples was collected by tapping into discharge of the shipâ€(tm)s seawater flow through system MIDAS. MIDAS intake was 2 -3 meters below the surface. The watch chief observed MIDAS navigational data, when distance to station was 0.3 miles, a triple-rinsed jar (1000ml) was collected from the silicon MIDAS discharge tube in the ship's bottle lab. Finally, collection time was logged.
Suspended sediment filters were dried 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.
Nitrogen and phosphorus are 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 is analyzed according to Technicon Industrial method 186-72 W/B (1977).
Sea-Bird CTD data were acquired using Seasoft version 4.225 in all months except September and October when version 4.217 was used. Data were post processed using Seasoft version 4.225. 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, when possible, 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 as follows: January, November and December +4.25 seconds; March, April, May, June and August +4.5 seconds; July +4.333 seconds.
Data values reported are from downcasts. Downcast scans selected for each CTD station were 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.
H99Hydrolab: The Hydrolab Surveyor 3 Conductivity, pH and Oxygen sensors were serviced and calibrated before deployment and maintained in accordance with Hydrolab (<http://www.hydrolab.com/>) recommended procedures. The Sonde and Logger are returned to the factory at least annually for inspection and service.
H99Nutrient: Nutrient analyses were conducted using a Technicon (<http://www.techniconinstruments.com/>) autoanalyzer by Tom Oswald under the supervision of R. E. Turner.
H99Pigment: The Turner Designs model 10 and model 10 AU fluorometers were calibrated for chlorophyll a against a chemical supply house chlorophyll a standard measured on a spectrophotometer yearly. During cruises, the fluorometer was blanked and calibrated daily in accordance with Turner Designs recommended procedures. Beginning in June 1999, a Turner Designs model 10 AU replaced the model 10. Each time the model 10 AU was moved, it was tested with a Turner 10-AU solid standard. Pigment measurements were supervised and quality controlled by Nancy Rabalais.
H99SeaBird: Sea-Bird SBE 13-01 dissolved oxygen sensors, the Paroscientific Digiquartz(r) pressure sensor, the SBE 3-01/F temperature sensors, SBE 5-01 pumps, and the SBE 4-01/0 Conductivity sensors were factory tested and calibrated at Sea-Bird (<http://www.seabird.com/>) recommended intervals and maintained and serviced by RV Pelican Electronic Technical support staff in accordance with Sea-Bird procedures. The Sea Tech 500m Fluorometer and Sea Tech 5.0 cm Transmissometer were factory tested and calibrated at Sea Tech recommended intervals and maintained and serviced by RV Pelican Electronic Technical support staff in accordance with Sea Tech procedures. Note: WET Labs acquired SEA Tech June 1, 1998, (<http://www.wetlabs.com/>). The Wet Labs WetStar fluorometer was maintained in accordance with Wet Labs recommendations by RV Pelican Electronic Technical support staff. The Chelsea Fluorometer was also maintained by RV Pelican Electronic Technical support staff in accordance with Chelsea recommended procedures (<http://www.chelsea.co.uk/>).
For the months January - June and August, the calibration of the SeaBird oxygen sensors was accomplished as follows. A large tub of clean seawater was mixed and aerated for 24 hours. The Sea-Bird CTD package was placed in the oxygen-saturated water bath for the next hour. The Hydrolab CTD, freshly calibrated, was also placed in the bath. Both CTD systems were powered up. The SeaBird Deck unit and Hydrolab logger were observed. Time for sensor equilibration was allowed.
The manufacturers stated +/- 0.2mg/L as the error allowance for both SeaBird and Hydrolab oxygen sensors. SeaBird and Hydrolab oxygen values were compared.
If the sensors agreed within 0.4mg/L, no further action was taken. If sensor values were more than 0.4mg/L apart, The Hydrolab value was used for the "W" value and the SeaBird oxygen sensor was calibrated using the procedure described in Seabird APPLICATION NOTE NO. 13-1, Rev. D.
At the beginning of the July shelfwide cruise, oxygen sensors were calibrated using the procedures described in Seabird APPLICATION NOTE NO. 13-1, Rev. D. The Winkler Titration (OXFITW) oxygen value was determined chemically from replicate samples processed using a Mettler DL21 Titrator (<http://www.mt.com/>). Shipboard Winkler titrations during the cruise were used to develop a regression against CTD data.
Winkler titrations and the OXFITW procedure were used to check the SeaBird oxygen sensors at the beginning of the September - December cruises.
The September and October cruises were made on RV Acadiana. On those cruises, the General Oceanics CTD rosette was not used and a SeaBird SeaCat CTD was used instead of the SeaBird 911+ CTD used on Pelican cruises. A pumped Sea-Bird SBE 13-01 dissolved oxygen sensor was employed on each of the September and October cruises. The September configuration file was used during the October cruise because it gave better post-calibration results than an October calibration adjustment attempt.
Winkler titrations were conducted under the supervision of Nancy Rabalais. Data reductions from the SeaBird were generated by Ben Cole and quality controlled by Nancy Rabalais.
H99Stn: Times and locations of operations were acquired from RV Pelican's Multiple Instrument Data Acquisition System (MIDAS), which was maintained by the ship's electronic staff. Navigational data were acquired from a Starlink (<http://www.starlinkdgps.com/>) differential GPS or a Trimble (<http://www.trimble.com/>)GPS with a Micronet Receiver Station with sub 5-meter accuracy. Station depths were logged from the ship's Odom Echotrac II (<http://www.odomhydrographic.com/>) fathometer. The Secchi disk depths were measured by hand using standard protocol.
During the September and October cruises on the RV Acadiana, RV Pelican's Starlink and Trimble GPS units were transferred to Acadiana. Position data were logged from the Starlink and Trimble GPS units. Station depths were logged from Acadiana's fathometer.
H99PortaSal: The samples were analyzed in the lab by Guildline Instruments PortaSal, using Guildine methods (<http://www.guildline.ca/>). Salinity analyses were conducted by Jim Lee under the supervision of R. E. Turner.
H99MIDAS: Suspended sediment concentrations were supervised and quality controlled by Nancy Rabalais. Times and locations of operations were acquired from the ships MIDAS system (described above in H99Stn).
N. Rabalais performed an additional procedure in quality-control/quality-assurance by evaluating relationships between the data in H99PortaSal, H99Hydrolab, H99Nutrient, H99Pigment, H99Stn and H99MIDAS.
All station positions, except those acquired during the September and October cruises on RV Acadiana, were logged from RV Pelican's differential GPS at the beginning of sampling operations. GPS manufacturer's accuracy claim is 1-5 meters 95% of the time. Wind, currents and tidal forces may move the ship from the beginning position.
Station positions acquired during the September and October cruises on RV Acadiana were logged from the ship's NorthStar 800 LORANC. The manufacturer describes the accuracy to be within 30 meters 90% of the time.
On the following dates hydrocasts were made from a small boat tied to the oilfield platform at station C6B: 19990301, 19990322, 19990428, 19990513, 19990520, 19990603, 19990624, 19990712, 19990730, 19990818 and 19990907.
There were problems with the SeaBird CTD plumbing configuration, software configuration, pump and deck unit failure during the February 2nd cruise. Oxygen data values were considered to be unreasonably high. Oxygen data were not included in the dataset because they were considered unreliable.
August 24th Hydrolab data were not acquired due to a battery problem.
SeaBird FlC (fluorescence Chelsea), FlS (Fluorescence Sea-Tech) and Xmiss (transmission percent) data were not acquired during the September 14th and October 12th surveys on RV Acadiana because of the reduced number of instruments in the SeaCat CTD package.
November 4th station C9 Seabird oxygen data were not included because the oxygen sensor failed.
During monthly surveys conducted in other months, shipboard Winkler titrations for regressions were not made due to logistical constraints. Fewer stations were sampled and water columns were often well mixed, making the considerable effort involved in titrating an inefficient allocation of resources. A suitable range of data could not be acquired to develop a strong regression.
Hydrolab data were derived from a pre- and post-calibrated instrument. Therefore, there is often disagreement between SeaBird and Hydrolab oxygen values. It is the opinion of the PI, Nancy Rabalais, that the Hydrolab data for the monthly cruises are the more reliable data.
For the July SeaBird data, Winkler titrations were used to develop a regression which was used to correct the SeaBird oxygen data if necessary. The data for the SeaBird and the Hydrolab compare better for the shelfwide July cruise.
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: 0.816 |
|---|---|
| Media you can order: |
3-1/2 inch floppy disk or CDROM
(format DOS Copy)
|
Call or write the Distributor with requests for data sets.
Contact distributor.
Contact distributor
Ben Cole or Adam Sapp
Louisiana Universities Marine Consortium
LUMCON, 8124 Hwy 56
Chauvin, LA 70344
USA
985 851 2800 (voice)
985 851 2874 (FAX)
Unknown