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.

Bathythermograph

A bathythermograph produces a continuous record of the temperature of water from the surface to a maximum depth of about 300 meters (984 feet). A profile of the temperature with depth indicates the degree of mixing in a lake.

The bathythermograph gets its name from a combination of three words: bathy (deep), thermo (heat), and grapheion (write). When they are combined into bathythermograph, the function of the instrument is contained in its name - an instrument that will give a record (graph) of the temperature (thermo) at various depths (bathy) below the surface of a body of water.

One of the special features of the bathythermograph, which can be abbreviated BT, is that the instrument can be used while the vessel is in motion. It is the shape of the BT that makes it possible to obtain a record of the temperature versus depth while the vessel is in motion. The BT is shaped like a torpedo with tail fins that keep it pointed in the direction the vessel is moving.

Inside the long body of the instrument are two mechanisms that produce the continuous record of temperature and depth. At the tail end of the BT, under the fins, is a small diameter copper tube that is filled with a fluid called xylene. The xylene changes its volume when the temperature of the water surrounding the tube changes. The change in volume results in a change in pressure within the xylene. The change in pressure causes a U-shaped chamber attached to the copper tube to change its shape. As the shape of the U-shaped chamber changes, it moves a pointer with a sharp point across the surface of a gold-plated glass slide. Thus the position of the pointer depends upon the temperature of the water surrounding the xylene-filled copper tube.

The pressure of the water increases as the depth of the water increases. The second mechanism in the BT is affected by the pressure of the water and, therefore, provides a method for indicating depth. The second mechanism is a bellows that compresses as the pressure (depth) increases when the BT is lowered into the water. The movement of the bellows moves the same glass slide that the pointer rests on. The combination of these two motions, the pointer moving according to the temperature of the water and the glass slide moving back and forth as the pressure changes, scratches a record in the gold coating on the slide of temperature and corresponding depth.

Two kinds of bathythermographs are used on the vessels: mechanized and data logger. The bathythermograph is kept in its storage box until it is to be used to prevent it from being bumped and damaged and to keep it from becoming too hot. When it is time for making a BT cast, the deckhand will ask the group assigned to the BT to bring the storage box to the middle of the aft deck.

Instructions for use of Bathythermograph for advanced trips:

NOTE: The bathythermograph is a piece of equipment that is operated by the deckhand with assistance from students. It is not a standard instrument used in all cruises.

1. The BT is removed from the box and held while its various parts are examined and explained to the group.
2. The sleeve covering the glass slide holder is moved toward the nose of the BT exposing the slide holder. A curved spring at the top of the slide holder will hold the glass slide securely in the slide holder grooves.
3. A new, unused glass slide is obtained from the plastic box containing the slides. The slide should be held between the thumb and forefinger at the edges to prevent touching the gold-coated face of the slide.
4. Insert the slide into the grooves of the slide holder so the edge with the special corner enters first and the corner is at the top or forward end of the slide holder. Push the slide in the grooves under the spring until it rests firmly against the stop pin. This is an important step since errors will be encountered in the readings if each slide is not positioned firmly against the stop pin.
5. Pull the sleeve toward the fins to cover the slide and holder. This will lower the tip of the pointer onto the glass slide. Lock the sleeve with the screw found near the fins. The BT is now ready to be lowered into the water to obtain a temperature versus depth record.
6. The BT is handed to the deckhand who will attach the instrument to the winch cable. While this is being done, information about the depth of the water and the temperature of the surface water is obtained. The depth of the water can be obtained from the fathometer. The value is reported to the deckhand so he or she will know how far to lower the BT. The temperature of a sample of surface water can be obtained by retrieving the water in a bucket and measuring the temperature with the thermometer furnished with the BT. Obtain the surface water sample at a location away from the engine exhaust outlets that are located near the stern of the port side.
7. The deckhand lowers the BT into the water and keeps it just below the surface for at least 30 seconds to allow the BT to adjust to the temperature of the surface water. He or she then lowers the BT to the predetermined depth. The BT is retrieved and brought on-board so that the glass slide can be removed and studied.
8. The sleeve is moved forward and a visual check is made to ensure that the tip of pointer is free of the slide. To remove the slide, push against its edge with a finger or pencil through the ejection port and remove the slide with fingers at its edges while exercising caution and care not to damage the gold-coated surface with the inscribed record.
9. After the slide is removed, it is checked to see if a suitable trace has been made. If any damage has been done to the slide, another lowering with a new slide will have to be made.
10. The BT is tilted back and forth to remove any trapped water. The outer surface of the BT is wiped dry and the instrument is returned to its storage box.
11. With a sharply pointed instrument, scratch a record of the necessary data onto the glass slide being careful not to damage the temperature scribe made by the instrument. In most cases, such information as the day, month, year, and time is scratched onto the slide.
12. To read the slide, insert the slide into the grid holder that is attached to the grid viewer. The grid viewer is found in the BT storage box. The slide should be inserted with the coated surface toward the grid. Exercise caution to avoid scratching the coated surface. Insert the slide until it rests firmly against the stop pin at the opposite edge of the grid holder. This is important in order to obtain an accurate reading from the grid.
13. Adjust the focus of the grid viewer and proceed with the reading of the slide scribe (the line scratched on the coated surface of the slide by the tip of the pointer) as it appears against the cross lines of the grid. The horizontal depth lines on the grid are curved. The temperature lines on the grid are the tilted vertical lines. Any point on the scribe can be accurately read on the grid and an accurate recording can be made. The center of the trace mark on the slide is the point at which a reading on the grid should be taken.
14. When the data have been recorded, remove the slide from the viewer and place in a slide box that is marked for used slides. Wipe off the viewer and return it to the BT storage box.

Phleger Corer

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.

1. The corer is lowered close to the bottom in a controlled manner.
2. 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.
3. 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.
4. 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.
5. 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.

Sea Bird Profiler

The Sea Bird Profiler is sophisticated instrumentation for measurement of parameters along a gradient in the water column. It consists of a frame on which is mounted sensors and a data logger. The information collected is processed using an on-board computer and graphs can be produced.

The Sea Bird Profiler has sensors for chlorophyll concentration, conductivity, depth, temperature, and light. The instrument has been adapted to record the light data from a Biospherical Instruments PAR light sensor. A transmissometer is designed to accurately measure beam transmission in a 10 centimeter water path. A fluorometer measures chlorophyll-a concentrations.

Spectrophotometers

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:

1. 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.
2. 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).
3. 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.
4. For analysis, turn on the DR/2010 and select the constant-on mode. Wait 5 minutes for the lamp to warm up.
5. 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:
   1. Select and enter the program number for the analysis.
   2. Rotate the wavelength dial to the proper wavelength.
   3. Add reagents to a measured volume of the sample.
   4. Wait the appropriate time for the reaction.
   5. Fill one sample cell to the fill mark with unreacted sample (blank).
   6. Fill the other sample cell to the fill mark with the reacted sample.
   7. Place the blank (unreacted) cell into the cell holder and close the light shield. Press "Zero" for the blank cell.
   8. Place the reacted cell into the cell holder and close the light shield. Press "Read" for the reacted sample cell.
   9. Record the display result

Specific methods in pictorial form are available on the vessels.

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