The data contain measurements for nitrogen organic total, nitrogen ammonia total, nitrogen AMM+ORG total, nitrogen nitrite total, nitrogen nitrate total, nitrogen nitrite+nitrate total, phosphorus total, and orthophosphorus total from 15 sites in Miami-Dade County. Data are available as separate files for each site or as data for all sites in one file in either Excel spreadsheets or tab-delimited text files.
Arthur C. Lietz (retired), 2001, Nutrients Data (Lietz).Online Links:
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.1. Longitudes are given to the nearest 0.1. Latitude and longitude values are specified in decimal degrees.
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257.
Project personnel included Frank Panellas, student civil engineer, John Goebel and Elizabeth Debiak, hydrologic technicians.
239 275-8448 ext. 10 (voice)
239 275-6820 (FAX)
mbyrne@usgs.gov
The ecological health of bays and estuaries has become a matter of concern throughout the country. Biscayne Bay, which is a shallow, oligotrophic, subtropical estuary along the southeastern coast of Florida has been adversely impacted in certain locations by the increase in nutrient loads from tributary canals that have resulted from agricultural, urban, commercial and industrial processes. The ecological health of the Bay, as well as development of restoration efforts is dependent in part on understanding loads to the bay. This task was undertaken to determine nutrient loads from the canals discharging into Biscayne Bay National Park
Depth-integrated and point (grab) samples for nutrients were collected from the gated control structures at the east coast canal sites in Miami-Dade County during periods of flow. Most of the samples were collected near low tide when the gates at the sites usually are open. Depth-integrated samples were collected by means of the equal-width-increment method, which commonly is used when a discharge measurement is not made before sampling. In this method, the width of the stream is subdivided into equal-width intervals with a sampling vertical associated with each interval.
In each cross section for the study, 8 to 10 verticals were used. The first vertical selected was half the distance of the first interval from the edge of the stream bank, and the other verticals were equally spaced apart across the stream from the first vertical. Because flow velocities of the east coast canals in Miami-Dade County are nearly always less than 2 ft/s (feet per second), the weighted-bottle method was used to collect each sample. The weighted bottle does not sample isokinetically (nozzle velocity equal to stream velocity); however, it can be used during low flows and when differences in water quality across the stream are believed to be insignificant. In the initial step, the vertical with the greatest velocity is selected; the weighted bottle is then lowered and raised at a constant rate so that it is not overfilled when returned to the surface. For each specific site, this transit rate was maintained throughout for all the verticals in the cross section, and a sample from each vertical was composited in a churn splitter for processing. The transit rate as well as the nozzle size was varied for each specific site in order to prevent overfilling of the bottle.
During sample processing, the water in the churn was stirred by the churn disc at a rate of about 9 in/s (inches per second) to minimize error, with care being exercised to prevent the churn disc from breaking the surface. A total of 125 mL (milliliters) of this composite sample was siphoned off into an amber polyethylene bottle, chilled immediately, and within 48 hours was shipped to the USGS Water Quality Service Unit in Ocala, Fla., for analysis. The constituents determined were total organic nitrogen, ammonia, nitrite, nitrate, nitrite plus nitrate nitrogen, total phosphorus, and orthophosphate. A point (grab) sample was collected concurrently with each depth-integrated sample. Point (grab) samples, depending on the site, were collected at 0.5 or 1.0 m below the surface near the centroid of flow by using a Niskin bottle. This bottle is spring loaded so that a messenger can trip it shut at the appropriate depth. After collection of the point (grab) sample, 125 mL of the sample was transferred from the Niskin bottle into an amber polyethylene bottle, chilled, and shipped for analysis according to protocol.
Before each sampling trip, the Niskin bottle, weighted bottle, and churn splitter were cleaned with a dilute nonphosphate detergent and then rinsed with tap water followed by deionized water. Two rinses with native water were required for the samplers before sample collection at each east coast canal site. Between sampling sites, the samplers were rinsed with deionized water before being rinsed with native water.
To ensure the integrity of the field data collected for the study, quality assurance samples (equipment blanks, field blanks, and split samples) were used extensively in the data-collection phase. Blank solutions essentially are samples free of the analytes being determined in the environmental samples. An equipment blank is a blank solution that is processed through all of the equipment used in the collection and processing of the environmental samples. Field blanks are actually equipment blanks done in the field and are subject to all aspects of the data-collection efforts as the environmental samples, including processing, preservation, transport, and laboratory handling. Two types of field and equipment blanks were used: one for the Niskin bottle and the other for the weighted bottle and churn splitter. These two field blank solutions consisted of inorganic blank water prepared at the USGS Water Quality Service Unit and were processed and analyzed according to protocol. Analytical results from the equipment blanks and field blanks indicated that most of the concentrations for the individual nitrogen and phosphorus species were below the detection limits for the analytical methods.
Split samples were collected concurrently by the USGS and DERM to verify interlaboratory accuracy. The sampling data consisted of point (grab) samples that were collected from the same Niskin bottle by both agencies. The samples were sent to the USGS Water Quality Service Unit and to the DERM laboratory for analysis.
Person who carried out this activity:
239 275-8448 ext. 10 (voice)
239 275-6820 (FAX)
mbyrne@usgs.gov
Lietz, A. C., 1999, Methodology for estimating nutrient loads discharged from the east coast Canals to Biscayne Bay, Miami-Dade County, Florida: Water Resources Investigations Report 99-4094, U.S. Geological Survey, Reston, VA.Online Links:
Lietz, A. C., 2002, Feasibility of Estimating Constituent Concentrations and Loads Based on Data Recorded by Acoustic Instrumentation: USGS Open-File Report 02-285, U.S. Geological Survey, Tallahassee, FL.Online Links:
Lietz, A. C., 2000, Analysis of Water-Quality Trends at Two Discharge Stations - One within Big Cypress National Preserve and One near Biscayne Bay - Southern Florida, 1966-94: Water Resources Investigations Report 00-4099, U.S. Geological Survey, Tallahassee, FL.Online Links:
Lietz, A. C. Dixon, Joann; Byrne, Michae, 2002, Average altitude of the water table (1990-99) and frequency analysis of water levers (1974-99) in the Biscayne Aquifer, Miami-Dade County, Florida: USGS Open-File Report 02-91, U.S. Geological Survey, Tallahassee, FL.Online Links:
The positional accuracy of the sampling sites was determined using GPS techniques and published topographic maps.
Most of the sites have data from either 1996 or 1997. Snapper Creek Canal and Tamiami Canal have data from both 1996 and 1997. Data was collected mostly during April - October for each year.
not applicable
Are there legal restrictions on access or use of the data?
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727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
hhenkel@usgs.gov
lietz - nutrients data
No warrantees are implied or explicit for the data
| Data format: | Data may be downloaded as one file for all sites or individual data files in format ASCII text (version unknown) tab-delimited Size: 0.032 |
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| Network links: |
<http://sofia.usgs.gov/exchange/lietz/lietznuts.html> |
| Data format: | The data may be downloaded as one file for all sites or as individual files in format MS Excel (version 2000) Size: 0.084 |
|---|---|
| Network links: |
<http://sofia.usgs.gov/exchange/lietz/lietznuts.html> |
727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
sofia-metadata@usgs.gov
U.S. Department of the Interior, U.S. Geological Survey
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