10 / 44
Ref. No. [UMCES] CBL 2017-050
ACT VS17-05
10
Reference Water Sample Collection
-
A standard 2L Van Dorn bottle was used at the CBL and HI
field sites to collect reference water samples for laboratory nutrient concentration analysis. For the
riverine test site a 1L acid-cleaned, polypropylene bottle was filled directly from the flow-through
tank. For the tank sampling, the sampling bottle was rinsed three times before filling. For the
mooring sites, the Van Dorn bottle was lowered to the same depth and as close as physically
possible to the sampling inlets of all instruments and less than 1 m from any individual sampling
inlet and soaked at sampling depth for 1 minute prior to sampling. The water sample was then
transferred to an acid washed 1L polypropylene bottle after three initial rinses of the field sample.
All environmental reference samples were processed within 10 minutes of collection while wearing
clean laboratory gloves to minimize potential sources of contamination. The sample was filtered
through a 47mm Whatman GFF filter into an acid cleaned vacuum flask. The first 50 ml of filtrate
were discarded as a rinse. The remaining filtrate was distributed into 8 individual acid-cleaned, 30
ml polypropylene bottles to provide three analytical replicates each for NO
3
and PO
4
plus two
replicates to hold as back-ups. All final sample bottles were rinsed once before filling and filled no
more than ¾ full to allow adequate headspace for freezing. The final reference samples were
immediately frozen and remained so until shipment to CBL-NASL for analysis.
Sample Handling and Chain of Custody
- All collected reference samples at each test site were
dated and coded according to site and sample sequence. Each sample container was labeled with a
number for identification. The reference sample number was used in all laboratory records and
Chain-of-Custody (COC) forms to identify the sample. Samples were shipped on dry ice to CBL-
NASL for nutrient analysis within approximately two weeks of collection. Shipping containers
were sent for next morning delivery, or the soonest possible delivery time possible from a given
shipping location. All samples, including the condition shipped and received, were recorded onto
Chain of Custody (COC) forms and a copy sent with the samples. The COC specified time, date,
sample location, unique sample number, requested analyses, sampler name, and required
turnaround time, time and date of transaction between field and laboratory staff, and name of
receiving party at the laboratory. NASL confirmed receipt and condition of samples within 24
hours of their arrival by signing and faxing a copy of the form to the test site.
Reference Sample Analysis
Phosphate concentrations for all reference and quality control samples were determined by
the NASL at CBL following their Standard Operating Procedures Manual (CEES, UMD,
Publication Series No. SS-80-04-CBL). The methodology is based on U.S. EPA Method 365.1, in
Methods for chemical analysis of water and wastes (United States Environmental Protection
Agency, Office of Research and Development. Cincinnati, Ohio. Report No. EPA-600-4-79-020
March 1979). In brief, ammonium molybdate and antimony potassium tartrate react in an acidic
medium with dilute solutions of phosphate to form an antimony-phospho-molybdate complex. The
complex is reduced to an intensely blue-colored complex by ascorbic acid. The color produced is
proportional to the phosphate concentration present in the sample.
Nitrate and nitrite concentrations for all reference and quality control samples were
determined by the NASL at CBL following their Standard Operating Procedures Manual (CEES,
UMD, Publication Series No. SS-80-04-CBL). The methodology is based on U.S. EPA Method
353.2, in Methods for chemical analysis of water and wastes (United States Environmental
Protection Agency, Office of Research and Development. Cincinnati, Ohio. Report No. EPA-600-
4-79-020 March 1979). In brief, nitrate is reduced to nitrite using the cadmium reduction method.
The nitrite is then determined by diazotizing with sulfanilamide and coupling with N-1-