GEOG 102 Mod 7 Lab

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Oregon State University, Corvallis *

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102

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Geography

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Apr 3, 2024

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Ruby McNamee GEOG 102 Week 7 Lab: Trash Talk: Can We Predict the Pathway & Decomposition of Trash in the Great North Pacific Garbage Patch? Part A (40 pts): Drifting Trash Data Calculations (22 pts) Figure 1 (at the end of the lab document, page 4) portrays the wind-driven surface ocean currents that are part of the vast circular gyres that form a major part of the oceans’ circulation. Figure 1 also shows the North Pacific Ocean, where the two main branches of the GNPGP exist. Scientists estimate that the upper level of this ocean gyre current flows at an average 3–4 km per hour. The distance between California and Japan is approximately 8,834 km. Figure 2 (at the end of the lab sheet, page 5) shows the estimated decomposition rates of common marine flotsam found circulating within the GNPGP. IMPORTANT INFORMATION: a. To calculate the average number of kilometers the gyre circulates in a day, multiply speed * 24 hours. You can use an average speed of 3.5 km per hour. b. To compute the number of days that each type of trash in Figure 2 travels before decomposing or, for microplastics, disappears beneath the surface: Multiply your result in (a) by the rate at which that particular type of trash decomposes (see decomposing rates in Figure 2). c. You MUST show your calculations in order to receive full credit on Questions 1-5. Use the above steps to calculate the answers for the following questions: 1. [4 pts] Calculate how many kilometers a newspaper would travel before decomposing. - Decomp time: 6 wks - A. 3.5 km/h x 24 hrs = 84 km - B. 84 km x 6 wks (42 days) = 3,528 km 2. [4 pts] Calculate how many kilometers a waxed carton container would travel before decomposing. - Decomp time: 3 months - A. 3.5 km/h x 24 hrs = 84 km - B. 84 km x 3 months (90 days) = 7,650 km 3. [6 pts] How far would a plastic grocery bag travel before breaking into microplastics (at which point the small pieces would take years more to eventually settle on the ocean floor)? Give your answer in both kilometers AND miles. - Decomp time: 10-20 yrs - A. 3.5 km/h x 24 hrs = 84 km - B. 84 km x 10-20 yrs (3652-7305 days) = 306,768-613,620 km or 190616.7979- 381285.791 miles 4. [4 pts] Compute how much farther a disposable diaper would travel within the gyre, compared to a tin can. - Disposable diaper decomp time: 450 yrs - Tin can decomp time: 50 yrs - A. 3.5 km/h x 24 hrs = 84 km - B. Diaper: 84 km x 450 yrs (164250 days) = 13,797,000 km - B. Can: 84 km x 50 yrs (18250 days) = 4,200 km - Difference: 13,792,800 km more
Ruby McNamee 5. [4 pts] How far in kilometers would a plastic bottle travel before decomposing? - Decomp time: 450 yrs - A. 3.5 km/h x 24 hrs = 84 km - B. 84 km x 450 yrs (164250 days) = 13,797,000 km [Extra Credit – 3 points] Would a plastic bottle thrown into the Pacific Ocean near Los Angeles break into microplastics before completing a full circuit around the gyre? To calculate this, use a string to mark the distance from Los Angeles, California, to Tokyo, Japan. This “length” equals 8,834 km between these two landmasses that border the North Pacific Ocean. Now use that metric and your answer from #5 to estimate the total length of the gyre (including the distance from the starting point in Southern California). - 8,834 km x 2 = 17,668 km is one full circulation around the gyre - A plastic bottle can travel 13,797,000 km before decomposing - 13,797,000 km / 17,668 km = 780.9 circuits - The plastic bottle would not break down before completing a full circuit around the gyre. According to my calculations, it could complete about 780.9 circuits before decomposing. Analyze & Conclude (18 points) About 60 years ago, nearly all flotsam was biodegradable materials such as wood, hemp rope, and wool. Today, non biodegradable plastics compose 90% of the GNPGP. Furthermore, almost 80% of trash originates from land-based activities, with the remainder coming off ships (mostly fishing nets) and debris from offshore oil platforms. 6. [4 pts] Determine the gyres and ocean currents within which a plastic bottle discarded off the coastline of eastern India would circulate (see Figures 1 and 2). - If it is discarded off the coastline of Eastern India, the plastic bottle would travel SW through the Indian ocean into the North Equatorial Current. It may also end up in the Equatorial Countercurrent, the South Equatorial Current, the West Australia Current, and the Agulhas Current. It would likely end up in the Indian Ocean Garbage Patch between South Africa and Australia. 7. [8 pts] Estimate the cardinal direction, ocean currents, gyres, and the number of kilometers a large piece of wood from an oil platform off the Florida Coast would travel until decomposing in the ocean waters (use the figures and your prior calculations). - If a large piece of plywood from an oil platform was in the ocean, it’s expected decomp time is 1-3 yrs (figure 1) - 3.5 km/h x 24 hrs = 84 km - 84 km x 1-3 yrs (365-1095 days) = 30,660-91,980 km - If discarded off the coast of Florida, the piece of plywood would likely travel through the Florida current, up into the Gulf Stream, through the North Atlantic Current, down the Canary Current, and end up circling through the North Equatorial Current in the North Atlantic Ocean. The wood would likely end up in the North Atlantic Garbage Patch between North America, South America, and Africa. It would end up East of where it was discarded. 8. [6 pts] Given what you have learned about this issue, suggest two strategies that you and your classmates could follow that would prevent the GNPGP from expanding. - To prevent expansion of the GNPGP, my classmates and I could take initiatives to encourage ourselves and those we know to avoid single-use plastics. We could create campaigns or fundraisers to enforce this idea throughout the
Ruby McNamee university. We could create groups who do cleanups around campus and other areas to minimize the amount of trash that is incorrectly discarded. Figure 1: Wind-driven surface currents and the Great North Pacific Garbage Patch
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