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Trap Data 2004/2005 Metadata

Sediment traps capture settling particles in the water column. Trap materials provide information about sedimentation and resuspension rates in different areas. 123 sediment trap samples were collected as a part of the 2004/2005 IFYLE program field seasons using 4 different trap configurations; 3 types are owned and were deployed by the Great Lakes Environmental Research Laboratory (GLERL) and one type is owned and was deployed by the Canadian National Water Research Institute (NWRI).

At different times and at different locations we deployed two different size automated sequential trap samplers and two different size passive trap samplers.

Based upon an earlier comparison of mass flux calculations and Reynolds number estimates from co-deployed examples of each style of trap we are rejecting the mass flux data from the automated sequential sampler 81 cm² traps. These traps over-collected settling particles and the data is not reported. We are accepting the mass flux data for the other 3 trap configurations.

Traps were either deployed on steel cable mooring lines or mounted on the frame of an instrumentation tripod at various stations and at various depths around Erie. Trap collection bottles were deployed pre-filled with DDW and spiked with either CHCl3, (6 ml/ 60 ml sequential sampler bottles; 20 ml /500 ml passive trap bottles) HgCl2 (25 mg / 500 ml passive trap bottles), or for the NWRI (35 m² traps) no poison was used.

We caution against direct comparison of trap data collected at 5m above bottom versus 1m above bottom. The GLERL 81 cm² passive sediment traps (1 sample per deployment) were in many cases deployed at 1m above bottom. These traps are presumed to have collected a higher proportion of particles resuspended from the lake bottom and are not considered to be directly comparable to materials that would be collected at higher elevations (i.e. 5m above bottom). Also these traps may have been “shadowed” by the tripod they were mounted to, perhaps creating an eddying effect which could have impacted particle settling rates.

Upon retrieval, all but the NWRI sediment trap samples were screened at 355um to remove larger biota and debris. Large debris was hand picked form the NWRI trap samples but they were not screened. For the GLERL trap samples, the > 355um screened material was back-washed onto filters, dried, weighed, and archived. The < 355um were freeze-dried, weighed, ground, and archived. A variety of chemical parameters were determined for the trap samples, but they were not measured on each trap sample. All the chemical constituent data we have has been submitted, if a parameter is missing, it was not measured, or in a few cases, was rejected.

The following parameters are reported in the IFYLE cruise data base: Mass flux, TC, TN, OC, ON, TP, del C-13, del N-15, FE, Zn, Mn, Al, Ti

The following researchers were involved in the collection and/or processing of the trap IFYLE 2004/2005 trap samples:

Contact Information:

Nathan Hawley
NOAA-GLERL
4840 S. State Rd.
Ann Arbor MI 48108-9719
(734)741-2273

Dr. Ram Yerubandi (deployment/retrieval, freeze drying of NWRI trap samples)
National Water Research Institute
Environment Canada
867 Lakeshore Road
P.O. Box 5050
Burlington, ON L7R 4A6

Phone: (905) 336-4785

Margaret Lansing (GLERL trap sample processing: size fractionation, freeze drying of GLERL trap samples, TC, TN, data collation & reporting)
NOAA-GLERL
4840 S. State Rd.
Ann Arbor MI 48108-9719

Phone: (734) 741-2210
Fax: (734) 741-2055

TC, TN: Carlo Erba EA 1100 CHN elemental analyzer

William E. Holmes (stable isotope mass spectroscopy: del C-13, del N-15, OC, ON)
Assistant Research Scientist
Terrestrial Ecosystems Laboratory
School of Natural Resources & Environment
University of Michigan
Ann Arbor, MI 48109-1041
Phone: 734-647-5925

Carbonates were removed from sub-samples of approximately 0.2 grams of trap materials by adding several milliliters of *2 N* HCL and mixing on a shaker table for several days_. The samples were then dried for 24 hours at 60°C and ground once again with a mortar and pestle before analysis for organic carbon and nitrogen content Samples were analyzed for ˆ15 N and ˆ13 C on a Delta Plus isotope ratio mass spectrometer with a Conflo II interface (Thermo Finnigan, San Jose, CA) Stable isotope ratios are calculated using the following equation:

dX= {(R_sample / R_standard)-1} x 103

Where X is ˆ13 C orˆ15 N, and R is the ratio of heavy to light isotope ˆ13 C/ˆ12 C or ˆ15 N/ˆ14 N. Calibrated laboratory standards are used for calculating the dX values which are adjusted and reported relative to PeeDee limestone for the carbon isotope, and atmospheric nitrogen for the nitrogen isotope. Isotopic ratios are expressed as d values in units “per mil” or ‰.

Tom Johengen (TP analysis)
Cooperative Institute for Limnology and Ecosystems Research
University of Michigan
Ann Arbor, MI 48109-1041

Phone: 734-741-2203

Total phosphorus was determined following the combustion method of (Anderson 1975). First, sediments were weighed into acid-cleaned Pyrex tubes, combusted for 2 hours at 450°C. Then, 30 ml of 1 N HCL were added to the sample, which was boiled in a water bath for 30 minutes. Samples were diluted up to 50 mls with deionized water and then analyzed on an Auto Analyzer II using Particulate Total Particulate (PTP): molybdate/ascorbic acid method

Leah Minc (neutron activation analyses, FE, Zn, Mn, Al, Ti values)
Oregon State University
Corvallis, OR 97331-4501

Neutron activation analyses were completed at the Oregon State University's TRIGA Mark II reactor (OSTR), in Corvallis, OR. The data for elements with intermediate and long half-life isotopes (including Fe and Zn), result from a 7-hr irradiation in the rotating rack of the OSTR, which experiences an average thermal neutron flux of 2E+12 n/cm2/s. Following irradiation, two separate counts of gamma activity were done: a 5000-second count (live time) of each sample after a 1-week decay period, and a 10000-second count (live time) after a period of 4 weeks decay.

In contrast, the data for short half-live isotopes (Al, Ti, and Mn) result from a 1-minute irradiation delivered via pneumatic tube to an in-core location with an average thermal flux of 1E+13 n/cm2/s. Again, two separate counts were necessary, one after a 13-minute decay (for Al and Ti) and a second count after 2-hr decay (for Mn); both counts are for 500 seconds.

All gamma counts were completed on a series of HPGe detectors with relative efficiencies ranging from 28-38%, using Canberra's Genie-VMS software for data acquisition, spectrum analysis, and data reduction. The concentrations of most elements were determined based on direct comparison with mean values obtained for three replicates of the standard reference material NIST1633A (coal fly ash). The Zn concentrations were based on NIST1648 (urban particulate).