Metadata

Description
Water samples were collected and analyzed by SERC personnel using standard methodology outlined in the Quality Assurance Project Plan (QAPP) with prior approval from SFWMD and FDEP. Salinity and temperature (degrees C) were measured 10 cm below the surface and 10 cm above the bottom using a combination salinity-conductivity-temperature probe (Orion model 140). Surface and bottom dissolved oxygen (DO, mg l-1) was measured using an oxygen electrode (Orion model 840), corrected for both salinity and temperature. Duplicate, unfiltered water samples were collected from 10 cm below the surface using sample rinsed, 120 ml HDPE bottles and kept at ambient temperature in the dark during transport. Duplicate water samples for dissolved nutrient analysis were collected using sample rinsed 150 ml syringes. These samples were filtered by hand (25 mm glass fiber GF/F) into acetone-washed and sample rinsed 60 ml HDPE bottles, which were then capped and immediately placed on ice in the dark for transport. The wet filters, used for chlorophyll a analysis (CHLA), were placed in 2 ml plastic centrifuge tubes to which 1.5 ml of 90% acetone was added. They were then immediately capped and put into a dark bottle on ice for transport. Unfiltered water samples were analyzed for total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), alkaline phosphatase activity (APA), and turbidity (NTU). TOC was measured by direct injection onto hot platinum catalyst in a Shimadzu TOC-5000 after first acidifying to pH<2 and purging with CO2-free air. TN was measured using an ANTEK 7000N Nitrogen Analyzer using O2 as carrier gas instead of argon to promote complete recovery of the nitrogen in the water samples. TP was determined using a dry ashing, acid hydrolysis technique. The APA assay measures the activity of alkaline phosphatase, an enzyme used by bacteria to mineralize phosphate from organic compounds. The assay is performed by adding a known concentration of an organic phosphate compound (o-methylfluorescein phosphate) to an unfiltered water sample. Alkaline phosphatase in the water sample cleaves the phosphate, leaving o-methylfluorescein, a highly fluorescent compound. The fluorescence of initial and 2 hr incubations were measured using a Gilford Fluoro IV spectrofluorometer (excitation = 430 nm, emission = 507 nm) and subtracted to give APA (uM h-1). Turbidity was measured using an HF Scientific model DRT-15C turbidimeter and reported in NTU. Filtrates were analyzed for soluble reactive phosphorus (SRP), nitrate + nitrite (NOx), nitrite (NO2-), ammonium (NH4+), and silicate (Si(OH)4) by flow injection analysis (Alpkem model RFA 300). Filters for CHLA content (µg l-1) were allowed to extract for a minimum of 2 days at -20degrees C before analysis. Extracts were analyzed using a Gilford Fluoro IV Spectrofluorometer (excitation = 435 nm, emission = 667 nm) and compared to a standard curve of pure CHLA (Sigma). Some parameters were not measured directly, but were calculated by difference. Nitrate (NO3-) was calculated as NOX - NO2-. Dissolved inorganic nitrogen (DIN) was calculated as NOX + NH4+. Total organic nitrogen (TON) was defined as TN - DIN. Concentrations for all of these water quality variables are reported in units of milligrams per liter (mg l-1) or the equivalent parts per million (ppm), except where noted. All nutrient concentrations are based on the atomic weight of primary nutrient species (ppm-N, ppm-P, and ppm-C), not the molecular weight. All N:P ratios discussed are calculated on a molar basis.

Citation
Jones, R. D. , J. N. Boyer. 2002. Annual Report of the South Florida Estuarine Water Quality Monitoring Network, SFWMD/SERC Cooperative Agreement #C10244.. Southeast Environmental Research Center (SERC) and South Florida Water Management District, 67.

Instrumentation
HF Scientific model DRT-15C turbidimeterGilford Fluoro IV spectrofluorometerAlpkem model RFA 300 Shimadzu TOC-5000oxygen electrode (Orion model 840)ANTEK 7000N Nitrogen Analyzer