Skipjack Martha Lewis

Information For The Martha Lewis Scientist
Water Quality Station (Educational Cruises)
Water Quality, though seemingly self-explanatory, is somewhat more complex than one might think. However, degrees of understanding the diversity of the chemical make-up of the Chesapeake Bay depend only upon how far you look. For our purposes we are looking just below the surface, excuse the pun, into the big players in the chemical composition of this body of water. We perform simple tests, which show us large phenomenon. As all the stations performed on board are interdependent and related, it is important to note the connection between the biological and the chemical. In doing so we will see clear reasons for why we find what we find within the waters we test.
Step 1. Conversation: To begin the station a brief conversation of chemistry and water quality should occur. Be sure that the students have an understanding of what is about to occur. Get them to then begin to talk freely about what they think they might see and what is important when we talk about water quality.	Questions: 1. Q: What is meant by the composition of water? A: Composition refers to the components or characteristics of the water which can be tested and hold some significance. 2. Q: What are those characteristics? A: Temperature, Salinity, Oxygen, pH, Nitrates, Phosphates 3. Q: Does anyone have any guesses before we get started about where these components come from?
Step 2. Temperature Temperature is the first experiment that occurs. It can be handled two ways. One is with the traditional thermometers. The other is with the electronic device. Temperature is very important. It is a key factor in sustaining life. Water that is too cold can kill of plants and animals, where water that is too warm may cause an unusual growth of algae and bacteria.
Step 3. Nitrates/Phosphates The next experiment to be done utilizes the Chemetrics kits for the specific chemical in question. Nitrates and phosphates are nutrients, which occur naturally. Nitrogen is essential for the synthesis of protein. It comes from decomposing organic matter (road kill, poop). Phosphorus is essential for cellular growth. Just like vitamins a human being might take the right amount of nutrients is key. Not enough and a level of sustainability may be threatened. However, too much can be equally as catastrophic. Too many nutrients cause an outrageous growth of phytoplankton, creating dense populations or “blooms.” These blooms become so dense that they block sunlight that the SAV need to survive and photosynthesize. As the plants weaken algae blooms begin to grow on the surface of the water, perpetuating the issue. And here we begin to get a sense of the “ecosystem perspective.” If those plants die, then they are unable to supply ample oxygen for all the living critters in the bay. When the critters die off, bigger critters have nothing to eat. It can even be easily stretched to the waterman who makes his living off of some of these critters. This is in fact one of the key reasons why our oyster population is in such peril. Disease from pollution has tipped the balance of the ecosystem. Safe Readings: 0.0-0.65 ppm Unsafe Readings: Anything above 0.65 Very rarely will you find there is not enough Nitrogen So where do these nutrients come from? 1.Farmer’s fields 2.Residential lawns 3.Acid rain (30%) 4.Runoff where water can bring animal waste and decomposing organic matter (road kill) into the bay 5.Sewage treatment discharge 6.Derergents How can you help? 1. Get your parents to drive less 2. Talk to farmers about safe fertilizing practices 3. Clean out gutters
Step 4. Dissolved Oxygen Oxygen is essential for life. It comes from the SAV under that water, and wind, rain, and currents on the surface. The depletion of the SAV population is the main source for a loss in dissolved Oxygen, especially in northern Bay. Cold water holds more oxygen than Hot water can. We find our lowest dissolved Oxygen readings on hot and dry spells when evaporation is at its highest. Hypoxia is a low Oxygen reading (aprox. 2 ppm). Anoxia is a complete absence of Oxygen. Most critters need aprox. 5 ppm to sustain life. We regularly will find 8-12 ppm. Q: When you hold an un-opened bottle of soda is it fizzing? A: No Q: Why? A: Because the carbonation is dissolved in the soda and under pressure. It is released when pressure is released, in this case the cap of the bottle. The bay is kind of like that. This may help the students grasp the idea that air is actually dissolved in the water like sugar in tea.
Step 5. pH Q: What is pH? A: pH is a unit measure of the quantity of acid in a solution. Q: Does anyone know what the pH scale is? A: 0-14. 7 is neutral. pH can become very complicated, so best to keep is simple. Explain that it is the level of acid and base in a solution and, like everything in the ecosystem neutrality is the optimal situation. In most ecosystems 7 (neutral will be the best situation for life. Acid levels are affected by acid rain, runoff, chemical spills, etc. Good Conditions for: Bacteria 1.0-13.0 Plants (algae and rooted) 6.5-13.0 Carp, Catfish, some insects 6.0-9.0 Bass, Crappie 6.5-9.0 Snails, Clams 7.0-9.0 Trout 6.5-7.5
Step 6. Salinity Q: What is salinity? A: The amount salt in the water. Salinity is very important for the bay because it dictates what kind of plants and animals we will find. Depending on the salt content the kind of ecosystem will change. The Chesapeake Bay is an estuary so there are freshwater environments, which occur far enough up every river, stream, and creek (including HDG) and salt water environments as you head down the bay. There are three categories of salinity (ppt): Fresh Water (HDG to Baltimore): 0 to aprox. 2 Brackish Water (Baltimore to Norfolk): aprox. 2 to aprox 28 Salt Water (Norfolk to England): above aprox. 28
Step 7. A Conclusion At this point you may have gotten to all the experiments, and maybe you did not, and that is ok. But conclude with a recap of what was covered. Ask each student one thing they learned that they did not already know. Talk about possible remedies for theses problems. Ask them questions. Make them ask you questions. When you are done send them on to the next station.
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