Instructor's Manual - Appendix B
Equipment For Advanced Cruises
College, advanced high school groups, and adult groups can request specialized cruises that use equipment not normally used on basic cruises. Special requests need to be made no later than two weeks prior to the date that the cruise is scheduled. Use of the following equipment is subject to its availability and the scheduling of the appropriate staff.
Hach DR/2010 portable spectrophotometers are available for advanced projects. The DR/2010 is a microprocessor-controlled, single beam spectrophotometer designed for colorimetric testing in the field or the laboratory. With a measurement range of 400 to 900 nm, the DR/2010 provides results in concentration units, percent transmittance (%T), and absorbance (ABS) units. There are factory-installed preprogrammed calibrations for more than 120 common water quality tests. Spectrophotometers are especially useful for nutrient studies, i.e. nitrate and phosphorus. Water hardness is another parameter that can be measured using a DR/2010.
General instructions for spectrophotometers:
- Two types of sample cells are available for the DR/2010: a matched pair of 25 mL cells and a matched pair of 10 mL cells. Both types are matched with the spectrophotometer light beam passing through the side with the fill mark and the opposite side.
- To minimize variability of measurements, always place the cell in the cell holder with the same orientation. The cells are placed in the instrument with the fill marks facing left (viewer's left).
- In addition to proper orientation, the sides of cells should be free of smudges, fingerprints, etc. to ensure accurate readings. Wipe the sides of the cells with a soft cloth before taking measurements.
- For analysis, turn on the DR/2010 and select the constant-on mode. Wait 5 minutes for the lamp to warm up.
There are a variety of analyses that can be done with the DR/2010 and the specific methods differ. However, the general procedure is to:
- Select and enter the program number for the analysis.
- Rotate the wavelength dial to the proper wavelength.
- Add reagents to a measured volume of the sample.
- Wait the appropriate time for the reaction.
- Fill one sample cell to the fill mark with unreacted sample (blank).
- Fill the other sample cell to the fill mark with the reacted sample.
- Place the blank (unreacted) cell into the cell holder and close the light shield. Press "Zero" for the blank cell.
- Place the reacted cell into the cell holder and close the light shield. Press "Read" for the reacted sample cell.
- Record the display result
Specific methods in pictorial form are available on the vessels.
The Phleger Corer is a weighted hollow tube that is used to penetrate the bottom sediment layers so that a study of the deposition of sediments can be made. A coring device is used for obtaining a sample at a greater depth in the bottom sediments. This device consists of a weighted hollow tube that is pushed into the bottom material by gravity. When retrieved, the material trapped in the tube is extruded and sliced lengthwise for examination of the various layers of sediments comprising the bottom material.
If the scientists, geologists for example, want to obtain a sample of bottom sediments to a depth greater than possible with a grab sampler, a coring device is used. Corers consist of a length of metal tubing with a sharp metal nosepiece on one end and a heavy weight on the other.
Instructions for use of Phelger Corer for advanced trips:
NOTE: The Phleger corer is a piece of equipment that is operated by the deckhand with the assistance of students. It is very heavy and awkward.
- The corer is lowered close to the bottom in a controlled manner.
- When it is approximately 5 meters from the bottom, the winch cable is played out rapidly so that the descent to the bottom is made in a free fall. The sharp cutting edge of the nosepiece and the metal tube penetrate the sediment, cutting out a cylinder of bottom sediment that is forced into the tube.
- A one-way valve inside will prevent the material from falling out as the corer is retrieved. To make it easy to extract the sediment sample, the metal tube has a plastic liner, which can be removed with the sediment sample inside.
- The sample can be left inside the plastic tube for storage and later examination. Plugs are inserted into the ends of the tube to prevent the sample from drying out.
- If immediate examination of the sample is to be made, a wooden plunger is inserted into the tube forcing the sediment sample out. A sharp knife can then be used to slice the core lengthwise. This will reveal different colored layers of sediment, if they exist.
GVSU classes sometimes have access to Hydrolab equipment. Hydrolab water quality instruments are known for their reliability in the field. Water quality data is taken with a multi-parameter probe for field surveying, and there are long term data-logging units. Hydrolabs are equipped with sensors for measuring temperature, conductivity, pH and dissolved oxygen, with options for turbidity, redox, and depth.
Page last modified January 11, 2013