Measuring Tools The measuring tools to the right have something in common can you tell what it is? (Hint: look at the shape...). Answer here...
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Bulge!
Back... |
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Estuary = Salty + Fresh
Activities
Wrapup Discuss why this is important in local waters. |
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A Neat Explanation
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A "good explanation" for these observations should be:
Essence of the Scientific Method! The explanation we'll examine is based on the atomic theory of matter and the kinetic theory of heat, fancy names for a simple set of ideas:
It's amazing how many different phenomena can be explained by these simple ideas—including our estuary observations:
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Science Pictures Here's a sampling of basic science pictures captured with a simple low-end digital camera. Some were obtained by holding the camera up to the eyepiece of a 40x dissecting microscope or similar instrument. |
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salt crystals (NaCl)Table salt |
This molecular model of an NaCl crystal, was made |
microscopic view of alga/seaweed
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another microscopic view of alga/seaweed |
Artemia (brine shrimp, "sea monkey") |
early larval stage of Artemia |
more advanced stage ("nauplius") of |
same, seen sideways |
adult male |
adult female |
Here is a cupful of adult artemia, seen from above, |
A well-populated artemia salad-bar aquarium. |
Salad-bar container aquarium for Artemia, with a mating pair. Sealed shut, and with only sunlight coming in, the closed ecosystem of alga and Artemia can sometimes last for generations. Some points are:
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An amphipod (relative of shrimp) from
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Webify! |
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Pioneer Real-time Water Data on the Web |
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The sonde, a YSI 600XL, is shown here dangling above the open end of a 2" PVC pipe, into which it just fits. In turn, the pipe (about 8' long), just fits into Pioneer's centerboard well, forward of the centerboard. The board has circular curvature around its pivot point near the lower forward corner, so the PVC pipe doesn't get in the way of the centerboard no matter how far it's raised or lowered—clearance less than .5", a small miracle! |
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The sonde is now in place at the bottom of the PVC pipe; the probes are about 1.5' below the surface. Note the cable's passing through the forward wall of the galley, emerging in the next picture... | |
Looking forward in the galley, we see the data/power cable from the sonde entering and running starboard to connect with 12 V DC power and to the cellphone modem. | |
The black cable from the sonde (running into this picture from the upper right) connects to a white computer serial cable (standard DB-9), and also to a 12 V DC power source. The galley lights DC circuit includes the female "cigarette lighter" style power socket, into which is plugged a 2-way splitter. One male plug carries 12 V to the sonde cable, which brings power to the sonde; the other male plug (barely visible on the shelf) brings 12 V DC to the cellphone modem. Starting Pioneer's engine often causes a power dip sufficient to reset the modem and sonde, and occasionally a manual reset is needed to bring the sonde back on-line (though usually it is automatically reset properly by the data-gathering software at Stevens Institute of Technology). | |
The cellphone modem is an Airlink PinPoint, with built-in GPS function as well as Internet capability. Through a wireless account with Verizon, the modem receives an Internet IP address, and sends and receives data and instructions (to both modem and sonde) over the Internet. | |
From the PinPoint modem below deck, antenna wires pass up through a (preexisting) through-deck, (another miraculous example of Pioneer's cooperation!), to the antenna pictured here, which receives GPS satellite signals, and separately broadcasts and receives Internet packets over the cellphone wireless network (a Verizon account, roughly $80/month). Coverage throughout the NY Harbor area seems pretty reliable, as does GPS reception.) | |
The data transmitted from Pioneer is received by computers at Stevens Institute, where it is stored in databases, and also rendered in real time into Web pages like this, which show the Pioneer's path, with different colors showing the values of a user-selected water measurement parameter (here, salinity). The path shown is that taken on 6/22/2005, for a press conference sail to officially inaugerate the data-taking program. The Web site is at Stevens Institute's Web site; the visitor can select a data and time range to view. At present (December 2005) the modem is back at Stevens, so that's the location shown till Pioneer's refitting next Spring. In the fall of 2005, DEP's Harbor survey vessel Osprey was also fitted with a cell modem, and this same Web page can be used to show Osprey's data and paths. |
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DEP Water Measurements at the Seaport Museum |
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The NYC DEP (Department of Environmental Protection) has installed at the South Street Seaport Museum an electronic measuring device (called a "sonde") that can measure and record various data about the water it's in. The Seaport sonde is on Pier 16; here DEP scientist Markus Koelbl takes it out of the water for maintenance, and to show a visiting class. The long black cable leads to a computer in the wetlab aboard Peking (whose rudder is in the background). |
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Here's what the sonde looks like. Normally it's about 10-15' below the water (depending on state of the tide). The bottom is where the individual measuring probes are located. | |
Markus shows and describes the sonde to a class visiting the Seaport for an education program... |
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Students listen while organizing chemicals and materials for their own water quality tests (bottles to right). | |
These students will be doing a test (called the Winkler test, after its inventor) to determine the amount of oxygen dissolved in the water. It's a bit complicated, as the steps to the left show; it is basically a "titration", in which you carefully measure how much you add, drop by drop, of some chemical to cause a color change to the sample measured. |
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Students here hold a sample (yellow liquid) as a solution (sodium thiosulphate) is added, drop by drop, with a syringe having measurement marks on it. The yellow color (due to dissolved iodine) fades as more thiosulphate is added. Iodine makes starch turn blue, so the color contrast can be strengthened by adding some starch later on (when the yellow gets too hard to see). | |
Once the tests are complete, extra sample material is disposed of properly. |
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Meanwhile, up in the wetlab, the sonde Markus took out of the water is attached to a computer, while a second one is ready to put in its place back in the water. When DEP first started working with a sonde here at Pier 16, they would bring a new one every month, replace the old one, and bring the old one up to their labs on Ward's Island, where the data would be transferred to a computer, and maintenance on the probes would be done as needed. | |
More recently, DEP started bringing a laptop for on-site downloading of data. There is software on the computer to control the sonde, get data from it, and display it in various ways. We now have computers full-time in the wetlab, connected to the sonde even when it's under water, so we can get the latest data by a few keystrokes or mouse clicks. | |
The sonde actually has multiple probes attached, as seen here—temperature, salinity, pressure (giving depth below surface), turbidity, chlorophyll content, and dissolved oxygen... | |
This is a close-up of the dissolved oxygen probe, which should give the same number as the Winkler test shown above. An interesting test is to compare the two measurements. | |
The software that gets the data can display graphs showing how the measurements change over time, as well as tables of actual numbers measured. | |
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