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Introduction

The coast of Alaska, one of the longest in the world, is bordered by many large bodies of water: the Pacific Ocean, Gulf of Alaska, the Bering Sea and the Arctic Ocean. By comparison, Massachusetts is only bordered by the Atlantic Ocean. Because of this amazing difference, I became interested in studying the ocean waters of Alaska, also known as oceanography. I became involved with this project as a member of the Young Explorers Team that went on the Harriman Expedition Retraced in Summer 2002.

As I learned more about oceanography, I became more interested in salinity and temperature. Although I understood the idea of temperature, I was less familiar with the idea of “salinity.” After doing some research, I found out that salinity is the amount of salts in one kilogram of water. Since I was going to be traveling the coast of Alaska by ship, measuring salinity and temperature seemed like a logical thing to do for a project. These two measurements are closely connected. In a laboratory, the hotter water gets, the more salt can be dissolved in it.

Using this idea, my project question is, “ Is the salinity higher in the warmer Southern waters of Alaska compared to the colder Northern waters?” As our ship traveled north toward the Arctic Ocean and the water got colder, does salinity go down?

Methods

Collecting salinity and temperature data was actually a lot of fun. The first thing that I had to do was make data sheets and put them in a book. The information that had to be collected on each sheet was the date, time, location, salinity, and temperature readings. Although there are three temperature layers of the ocean, my project focused on the surface layer. To do this, each time the ship anchored I asked a crewmember to help me get a bucket of water off the stern. The crew was always helpful and seemed interested in what I was doing.

Measuring salinity and temperature

Once the bucket was on the stern, I used a Palm Pilot with a temperature and salinity probe to gather my data. Each reading was entered into my data book. I also took water samples at each location by putting sea water in a clean plastic bottle and labeling it. I analyzed my data first by making a spreadsheet based on each location that I collected data. Then I used a chart wizard software program to make the charts.

Results

Table 1 shows the 32 locations where salinity and temperature measurements were taken.

Table 1 - Salinity and Water Temperatures
 LOCATION SALINITY H2O TEMP Metlakatla 27.7 51.03 Wrangell 12.2 51.26 Juneau dock 15.2 50.17 Skagway dock 4.2 47.72 Sitka dock 27.4 55.90 Yakutat dock 27.0 57.00 Kayak Island 29.7 56.64 Cordova dock 27.1 51.26 Valdez 5.4 43.82 College Fiord 27.2 40.64 Harriman Glacier (Face) 3.3 36.98 Harriman Glacier (1.5 mi out) 13.9 42.60 Latouche Island 24.1 58.47 Kenai islands 24.6 51.39 Kenai Fiord 24.3 57.61 Kodiak dock 31.3 53.34 Kukak Bay 25.4 59.08 Chignik 31.0 54.80 Unga Island 32.7 52.73 Otter Cove 32.8 53.71 Dutch Harbor 34.6 51.51 St.George 33.7 47.11 St.Paul 33.6 48.09 St.Matthews 33.7 43.45 Hall Island 33.8 45.65 St.Lawrence 33.2 45.53 Teller 19.2 50.17 Little Diomede 34.4 40.52 Cape Dezhnev, Russia 28.5 39.55 Lorino, Russia 30.4 41.74 Itygran, Russia 34.0 38.94 Yanrakino, Russia 32.5 43.94

Chart 1: Southeast/Central, sample points 1-8. The average temperature was 52.6 dgF. The average salinity was 21.3 ppt. Wrangell, Juneau, and Skagway all pulled down the average salinity. These three locations are within the Inside Passage and they are influenced by water coming from land. Each is right next to a freshwater river. All the other locations are more effected by the ocean. The temperatures are all about the same.

Chart 2: Prince William Sound, samples 9-12. The average temperature was 41 dgF. The average salinity was 12.5 ppt. I removed these sample points from the Southeast/Central samples because they are so different from the other areas. Prince William Sound is surrounded by many large glaciers that empty into Prince William Sound. Glaciers are freshwater sources that make the salinity drop. The temperatures are also lower then chart 1, because glaciers are colder then average ocean water.

Chart 3: Central/West, samples13-21. The average temperature was 54.7 dgF. The average salinity was 29 ppt. Compared to chart 1 and 2, the salinity and temperatures shown in chart 3 are steady throughout the Central/West region. All of the locations are influenced by the waters of the Gulf of Alaska and Pacific Ocean. However, the salinity gradually increases as the sample locations move west, farther away from glaciers of the Kenai Peninsula. Compared to charts 1 and 2 the temperature also increases as the influence of glaciers decrease.

Chart 4: Bering Sea, samples 22-32. The average temperature was 44.1 dgF. The average salinity was 31.5 ppt. The pattern in chart 4 is steady like chart 3, except for sample 27, Teller. Teller’s bay is enclosed by a long sandbar that traps freshwater coming from the land. As a result, the salinity drops and the temperature goes up. Salinity is higher in chart 4 then in any other region. This is because glaciers do not influence this area the way they do in all the other regions. This region has the coldest temperature except for Prince William Sound that is heavily influenced by the cold glacier water.

Chart 5: A comparison of salinities and temperatures by the regions described in Charts 1 through 4.

Chart 6: A comparison of sample locations that have been influenced by freshwater/glaciers (Wrangell, Juneau, Skagway, Valdez, Harriman Glaciers, and Teller) to locations that are not heavily influenced by freshwater. It is clear that freshwater and the cold water of glaciers causes the salinity and temperature.

Conclusion

My original question was, “Is the salinity higher in the warmer Southern waters of Alaska compared to the colder Northern waters?” My data actually shows the opposite. In Chart 5, you can see that in the more northern areas of Central/West and Bering Sea, the salinity increases. This is because the environment affects the salinity and temperature in many different ways, unlike a laboratory experiment. I found that glaciers and freshwater rivers heavily influence salinity and temperature regardless of whether you are in the north or the south (Chart 6). Wrangell, Juneau, and Skagway (Chart 1) are and Teller (Chart 4) places where freshwater has a big influence. Freshwater from glaciers had a big impact on salinity in Prince William Sound (Chart 2).

Calving glacier

Glacier ice cubes

It is clear that the different shapes of land affect the salinity and temperature. The Inside Passage, Prince William Sound, and Teller (Chart 1, 2, 4) are all land shapes where fresh water coming from the land gets trapped and does not get mixed up with the more salty ocean water. In the Central/West region and Bering Sea (Chart 5) the shore is directly on the ocean and the salinity is higher. So, there are three things that influence salinity: the amount of salt that can dissolve in water, the amount of freshwater that is put into the ocean water, and the shape of the land surrounding the water.

Bibliography

Bartsch, Paul, et al. A Bibliographical and Short Biographical Sketch of William Healey Dall. Washington, D.C.: Smithsonian Institution, 1946.

Foresman, Scott. Science Insights: Exploring Matter and Energy: Addison Wesley Longman, Inc., 1999.

Hill, Amy, Marine Biology, An Introduction to Ocean Ecosystems. Maine: J. Weston Publisher, 1995.

Norcross, Brenda, Professor of Fisheries Oceanography, Institute of Marine Science Alaska Fairbanks. Unpublished communication, July 2001.

Pearson, Roger and Hermans, Marjorie, eds. Alaska in Maps: A Thematic Atlas. Fairbanks, Alaska, Institute of the North, University of Alaska, 2000.

Peckol, Paulette, Professor of Marine Biology, Smith College. Personal communication. Unpublished communication, February 18, 2002.

White, Virginia, Chemistry Instructor, Smith College. Unpublished communication, February 18, 2002.

Wockley, Melissa, Teacher of Marine Biology, Williston Northampton. Unpublished communication, spring and summer, 2001.

World Wide Web Sites
Chamberlin, Sean. “The Seasonal Thermocline and Its Effect on Phytoplankton”
World Wide Web, Oceans on Line. National Oceanic and Atmospheric Admistration.

Office of Naval Research. “Ocean Water: Salinity, Focus Ocean Web site.

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