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Day 16｜読まなくていい部分を見極める

【メイン課題】

以下の英文を 4分〜5分以内 に読みましょう。

英文：
Microplastics, tiny plastic particles less than five millimeters in diameter, have become one of the most widespread pollutants on Earth. These particles come from various sources, including the breakdown of larger plastic waste, synthetic clothing fibers released during washing, and microbeads found in personal care products such as facial scrubs, toothpaste, and body wash. Recent studies have detected microplastics in virtually every environment on the planet, from the deepest ocean trenches to the peaks of remote mountains, and even in Arctic sea ice.

The impact of microplastics on marine ecosystems is a growing cause for concern among scientists. Small marine organisms such as plankton and shellfish ingest these particles, which then accumulate in larger animals as they move up the food chain. Research conducted by marine biologists at several universities, including the University of Plymouth, the National University of Singapore, and Kyoto University, has found microplastics in the digestive systems of fish, seabirds, whales, and sea turtles. The long-term effects on marine biodiversity remain uncertain, but early evidence suggests that microplastic contamination may affect reproduction, growth, and survival rates in some species.

Perhaps most alarmingly, microplastics have been found in human food and drinking water. A study published in the journal Environmental Science and Technology estimated that the average person may consume between 39,000 and 52,000 microplastic particles per year through food alone. When inhalation is included, this number could exceed 74,000 particles annually. Bottled water contains significantly more microplastic particles than tap water, with some brands containing over 10,000 particles per liter. The potential health effects of ingesting microplastics are still being studied, but there are concerns that the chemicals absorbed by these particles could disrupt hormone function and cause inflammation.

Efforts to reduce microplastic pollution are underway at various levels. Several countries have banned microbeads in cosmetic products. Advanced washing machine filters are being developed to capture synthetic fibers before they enter wastewater systems. Scientists are also researching biological solutions, such as enzymes and bacteria that can break down plastic materials. However, given the enormous quantity of plastic already in the environment, complete removal of microplastics is virtually impossible. Prevention through reducing plastic production and improving waste management remains the most practical approach.

設問：
（1）以下の情報のうち、文章の主旨を理解するのに「読まなくてよい部分」にあたるものはどれか。
a. マイクロプラスチックの定義（直径5ミリ未満）
b. パーソナルケア製品の具体例（洗顔料、歯磨き粉、ボディウォッシュ）
c. 研究を実施した大学名（プリマス大学、シンガポール国立大学、京都大学）
d. 年間の推定摂取量（39,000〜52,000個）
（2）本文の内容と一致するものを全て選びなさい。
a. マイクロプラスチックは北極の海氷からも検出されている
b. ボトル入りの水は水道水よりマイクロプラスチック粒子が多い
c. マイクロプラスチックの完全除去は現実的に可能である
d. 複数の国がコスメ製品のマイクロビーズを禁止している
（3）文章全体の主張を日本語1文でまとめなさい。

【練習問題】以下の英文を4分〜5分以内に読み、設問に答えなさい。

英文：
Space debris, also known as space junk, refers to defunct satellites, spent rocket stages, and fragments created by collisions and explosions in Earth’s orbit. According to the European Space Agency, there are currently over 36,000 objects larger than 10 centimeters, approximately 1 million objects between 1 and 10 centimeters, and an estimated 130 million particles smaller than 1 centimeter orbiting the planet. Even tiny fragments pose a serious threat because they travel at speeds exceeding 28,000 kilometers per hour.

The growing amount of space debris endangers active satellites and crewed spacecraft, including the International Space Station. In 2021, the ISS had to perform an emergency maneuver to avoid a piece of debris from a Russian anti-satellite weapon test. Collisions between objects in orbit can create thousands of additional fragments, potentially triggering a chain reaction known as the Kessler Syndrome, which could render certain orbital zones unusable for decades.

Several organizations are developing technologies to remove debris from orbit. The Japan Aerospace Exploration Agency is testing a magnetic tether system that would slow debris and cause it to reenter the atmosphere. A Swiss startup called ClearSpace is planning a mission to capture and deorbit a large piece of debris using robotic arms. These efforts are still in early stages, and no large-scale debris removal system is currently operational.

International cooperation is essential for addressing the space debris problem. Currently, there are no binding international regulations governing debris cleanup or the responsible disposal of old satellites. Without clear rules and shared responsibility, the problem will continue to worsen, threatening the satellite services that modern society depends on for communication, navigation, weather forecasting, and countless other applications.

設問：
（1）地球の軌道上にある10cm以上の物体は何個以上あるか。
（2）ケスラーシンドロームとは何か、本文に基づいて説明しなさい。
（3）文章全体の主張を日本語1文でまとめなさい。

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