北太平洋垃圾带的形成与变化Formation and Variation of the Great Pacific Garbage Patch

Formation and Variation of the Great Pacific Garbage Patch

Xiaoben Liu, Liuwu Shi, Yue Zhao

Abstract

We build four models to do a deep analysis on the formation, variation and distribution of the Great Pacific Garbage Patch. The first two models are created to research the mechanism of how the garbage island comes into existence from a microscopic scale. The velocity of trash alleviates as time goes on. Trash does its motion in two probable ways, one is due to resistances given by sea water, another is due to damp vibration. Using classic physical theories, we capture main motives propelling trash into the North Pacific Gyre. The third model is a compartment model aiming to find the possible increasing amount of trash in the garbage patch. A function of total garbage amount is extrapolated from the model.We use this model to predict that the number of plastic debris will be more than three times larger in the next 10 years successfully. In our fourth model, we work out a density function. Using the function, we depict the temporal and spatial distribution of garbage in the ocean. We also make a simulation reflecting its distributing rules more obviously. At last, we release some suggestions to prohibit deterioration in the Great Pacific Garbage Patch. Introduction

Where is the largest landfill in the world? It’s in the Pacific Ocean, about one thousand kilometers near the shore of America, called the Great Pacific Garbage Patch. It’s a specific area between California State and Hawaii, but until now there’s no accurate estimation about its coverage. The Great Pacific Garbage Patch is notorious for its high concentration of littered trash, plastic debris. According to a recent investigation, 80 percent of the trash is from main continents, 10 percent consists of used nets or other fishing tools and the other

10 percent of trash is from passing-by ships. Most of the garbage islands are in

oceanic gyres.

Undoubtedly the accumulation of garbage has already made huge negative influence on the environment. Large amount of oceanic animals die of eating up plastic trash by mistake. It’s a critical moment to release some feasible and practical methods to prevent deterioration.

Proper methods involve comprehensive information about the object. We verify many basic parameters characterizing the formation process of the huge landfill. The effect of ocean current is considered as the top factor in transferring garbage to America seashore.

We build several models to solve three problems separately: the accumulation and motion of trash on the Pacific Ocean; the increasing ratio of the garbage amount in Great Pacific Garbage Patch; the distribution of the garbage density in Great Pacific Garbage Patch.

The first question

The first section mainly discusses the possible motion track and the way how trash pile in the Pacific Ocean. There are two mechanisms of how trash thrown into the oceanic gyre.

Let’s start from the Great Pacific Garbage Patch. In our analysis, main mechanism for formation of this garbage area is due to force reactions on trash.

As trash is floating in the current, it has a velocity similar to that of the current.

When trash moves out the current, it enters a district where no wind exists.

Forced by water resistances, the initial velocity decreases with a certain acceleration. Finally trash stays static in some area in the oceanic gyre. As time goes on, more trash accumulates in the district, forming a garbage patch.

Assumptions

Velocity of trash is low enough to calculate resistance given by water using the formula: f kv

.

All the debris has discrete motion without conglomeration.

Oceanic surface out of the currents is considered to be static.

Ignore the differences generated by various figures.

Glutinosity of sea water is neglected.

Our first model

According to our discovery, the North Pacific Current doesn’t keep its motion direction as a uniform straight line. As we can see from Figure 1, the North Pacific Current branches near the pacific garbage patch. Consequently trash is conveyed inside the oceanic gyre.