Summary of Method. Water samples are filtered and analyzed by ion chromatography (IC). Each analytical batch consists of a blank, 5 external calibration standards and a calibration check for every 8 samples. The method detection limits (MDL) are as follows: 0.1 mg/L for phosphate, and 0.05 mg/L for nitrite and nitrate.
Preparation of IC samples. Water samples are pre-filtered before analysis in the Dionex ICS-90 ion chromatography system. Fresh water samples (5 mL) are filtered through 0.20 mm IC Millex syringe filters (for freshwater samples) while saltwater samples are filtered through the Dionex Ag/H cartridges and diluted 50:50 using deionized distilled water.
Preparation of IC calibration standards. The following calibration standards are prepared. (1) 0.1 mg/L of phosphate, 0.05 mg/L of nitrite and 0.05 mg/L nitrate (2) 0.2 mg/L phosphate and 0.1 mg/L nitrite and 0.1 mg/L nitrate (3) 1.0 mg/L phosphate and 0.5 mg/L nitrite and 0.5 mg/L nitrate (4) 2.0 mg/L phosphate and 1.0 mg/L nitrite and 1.0 mg/L nitrate (5) 10.0 mg/L phosphate and 5.0 mg/L nitrite and 5.0 mg/L nitrate
Calibration. The calibration curve must consist of at least three data points. The response of each calibrator must be within 10%, otherwise, it does not meet method criteria and must be removed from the working calibration curve.
Final data are summarized in Excel worksheets. The nitrite as N (mg/L) is calculated by multiplying the nitrite (mg/L) with 0.304 (factor). Likewise, the nitrate as N (mg/L) content is calculated by multiplying the nitrate (mg/L) content with 0.226 (factor). The phosphate (mg/L) content is converted to phosphorus (mg/L) by using the factor of 0.326.
Determination of Total Nitrogen and Total Phosphorus
Summary of Method. To analyze the total N and total P content, all phosphorus-and nitrogen-containing substances in the water sample are first converted to inorganic nitrates and phosphates by photo-oxidation. After photo-oxidation, the samples are analyzed as described above.
Photo-oxidation. Water samples (100 mL) added with 2 drops of 30% H2O2, are photo-oxidized using Ace-Hanovia photooxidation apparatus (Department of Health State Laboratory) for four (4) hours to hydrolyze all phosphorus-containing substances into phosphates, and all nitrogen-containing substances into nitrates.
File comment HeeiaCN1202-0403.xls Combined Nitrogen HeeiaLead0303-1103.xls Total Lead HeeiaTN1202-0403.xls Total Nitrogen HeeiaTP1202-0403.xls Total Phosphorous
Sample dates, locations, and units are defined in each file Redundant ASCII copies were made of each with same file name except for a CSV (Comma Separated Version) extention.
The following were downloaded off the internet, <http://www.wcc.hawaii.edu/water/>
Directory ../../data/figs_text The following files contain plots and a table of the data found in the Excel files described above:
combined_nitrogen_plot_table.gif total_phosphorous_plot_table.gif lead_plot_table.gif totalnitrogen_plot_table.gif
These files have descriptions and comments regarding each parameter:
combined_nitrogen_discussion.txt total_phosphorous_discussion.txt lead_discussion.txt totalnitrogen_discussion.txt
More information regarding the data collection locations can be found in directory ../../data/sites:
Figures depicting location: HeeiaSiteMap.jpg HeeiaSite01.jpg HeeiaSite02.jpg HeeiaSite03.jpg HeeiaSite04.jpg HeeiaSite05.jpg HeeiaSite06.jpg HeeiaSite07.jpg HeeiaSite08.jpg
Descriptive text and discussion: HeeiaSite01.txt HeeiaSite02.txt HeeiaSite03.txt HeeiaSite04.txt HeeiaSite05.txt HeeiaSite06.txt HeeiaSite07.txt HeeiaSite08.txt