雅思課外讀物--New theory for the Mass Extinction（大規(guī)模滅絕）近年來,，科學家們對地球歷史上發(fā)生的幾次大規(guī)模滅絕事件進行了深入研究,，尤其是奧陶紀和志留紀之間的滅絕事件。本文將探討一種新的理論,，認為海洋中氧氣的減少導致了有毒金屬的釋放,，從而引發(fā)了這一災難性事件。

新研究表明,，海洋中氧氣的減少可能釋放出有毒金屬,，這些金屬在地球歷史上曾引發(fā)過大規(guī)模的生物滅絕。高濃度的鉛,、砷和鐵等金屬,，至今仍對動物和人類造成危害，可能導致古代微小浮游生物出現(xiàn)致命的畸形,。

在約4.45億到4.15億年前的奧陶紀和志留紀期間,，發(fā)生了一系列滅絕事件，導致地球上85%的動物物種消失,。這是歷史上第二大規(guī)模的滅絕事件,，當時幾乎所有的動物都生活在海洋中。

科學家們曾提出多種可能的解釋,，包括急劇降溫,、火山氣體毒害大氣或超新星的伽馬射線爆發(fā)，但缺乏確鑿證據,。

新的理論則認為,，海洋化學成分的變化是罪魁禍首,。當海水中的氧氣因營養(yǎng)物質的涌入而減少時,，海底自然存在的金屬會溶解到水中。

根據《自然通訊》發(fā)表的研究,，金屬的增加被認為導致浮游生物產生“畸形”,。研究人員描述了這些畸形的生物，如“連體雙胞胎”,，或者卵子未完全分開的情況,。

參與研究的古生物學家Thijs Vandenbroucke表示，他們在利比亞沙漠深達1.3英里的鉆孔中發(fā)現(xiàn)的化石顯示，畸形現(xiàn)象比預期多出100倍,，重金屬濃度則高出10倍,。這些畸形在一種名為chitinozoans的微小瓶狀卵中尤為明顯。

如今,，類似的畸形在海洋和淡水生物中也有發(fā)現(xiàn),，提示這些生物暴露于高濃度的有毒金屬。研究合作者Poul Emsbo指出,，現(xiàn)代硅藻的殼體也會出現(xiàn)變形,，例如呈鋸齒狀，而這些變形通常用于檢測水中的金屬污染,。

雖然光照,、pH值或鹽度變化也可能導致海洋生物畸形，但科學家們發(fā)現(xiàn),，在奧陶紀-志留紀滅絕開始時,，這些因素幾乎沒有證據。因此,，研究人員得出的結論是,，高濃度的有毒金屬最可能是導致這一事件的原因，并可能在其他古代大規(guī)模滅絕中發(fā)揮作用,。

加州大學戴維斯分校的古氣候學家Howard Spero表示,，這是他聽過的關于奧陶紀滅絕的較新假說之一。他對冰蓋作為大規(guī)模滅絕觸發(fā)因素持謹慎態(tài)度,，因為冰河時代可能持續(xù)時間太短,。而海洋化學在其中的作用則顯得非常引人注目。

重金屬能破壞海洋生物的貝殼形成,，同時也對魚類,、鳥類及其他動物，包括人類,，造成危害,。鉛對所有脊椎動物都具有極高的毒性，而砷則可能導致癌癥,。

盡管科學家們無法確切說明數百萬年前海洋中氧氣的減少原因,，但目前的主要理論集中在營養(yǎng)物質（如氮）的增加上，這使植物快速生長并耗盡氧氣,。

雅思課外讀物--New theory for the Mass Extinction（大規(guī)模滅絕）通過這項研究,，我們對歷史上大規(guī)模滅絕事件的成因有了新的認識，也為現(xiàn)代環(huán)境問題提供了警示,。希望更多的研究能夠進一步揭示這些復雜的生態(tài)變化背后的機制,。

As an IELTS candidate, understanding various topics can significantly enhance your preparation. One intriguing topic that often appears in discussions is the "Mass Extinction Theory." This theory explores the events that have led to the significant decline of biodiversity on Earth. In this article, we will delve into the key aspects of this theory, providing insights and tips for IELTS preparation.

Understanding Mass Extinction ??

The term "mass extinction" refers to a period in Earth's history when a substantial number of species went extinct in a relatively short time. There have been five major mass extinctions identified by scientists, each caused by different factors such as volcanic eruptions, climate change, and asteroid impacts. The most famous of these is the Cretaceous-Paleogene extinction event that led to the demise of the dinosaurs about 66 million years ago.

Key Vocabulary for IELTS ??

• Extinction: The state of a species no longer existing.
• Biodiversity: The variety of life in the world or a particular habitat.
• Catastrophic: Involving sudden great damage or suffering.
• Ecological Impact: The effect of an event on the structure and function of an ecosystem.
• Fossil Record: The total number of fossils that have been discovered, providing evidence of past life.

IELTS Writing Task 2 Sample Question ??

"Some people believe that the extinction of certain species is a natural part of evolution, while others argue that human activity is the primary cause. Discuss both views and give your opinion."

Structure Your Response ???

When tackling this question, consider structuring your essay in the following way:

1. Introduction: Introduce the topic and present both viewpoints.
2. Body Paragraph 1: Discuss the natural aspect of extinction, citing examples from history.
3. Body Paragraph 2: Explore how human activities contribute to extinction, such as habitat destruction and pollution.
4. Conclusion: Give your opinion based on the arguments presented.

Listening Practice ??

For listening practice, find a podcast or documentary related to mass extinction. Pay attention to the vocabulary used and take notes on key points. This will help improve your comprehension skills and familiarize you with the topic.

Reading Comprehension ??

Read articles from reliable sources like National Geographic or scientific journals discussing mass extinctions. Focus on understanding the causes, effects, and current implications of biodiversity loss. This will not only enhance your reading skills but also provide content for your writing tasks.

New Topics to Explore ??

As you prepare for IELTS, consider exploring related topics such as:

• The impact of climate change on wildlife.
• Conservation efforts and their effectiveness.
• The role of technology in preserving endangered species.

Practice Speaking ???

Engage in conversations about mass extinction with peers or tutors. Discuss your thoughts on its implications and share your opinions on how we can mitigate human impact on biodiversity. This will enhance your speaking fluency and confidence.

By understanding the Mass Extinction Theory and incorporating it into your IELTS preparation, you can develop a well-rounded knowledge base that will serve you in both the writing and speaking sections of the exam. Remember to stay engaged with the material, practice regularly, and utilize the resources available to you. Good luck with your IELTS preparation! ??

Preparing for the IELTS can be a daunting task, especially when it comes to the Reading section. One of the key components that many candidates often overlook is the importance of familiarizing themselves with science reading materials. In this article, I will share some effective strategies and tips on how to tackle science-related passages that frequently appear in the IELTS exam. ??

Understanding the Format

The IELTS Reading section consists of three passages, and while they can cover a range of topics, scientific texts are common. These passages may include graphs, diagrams, and research findings. It’s essential to understand that these texts often have a specific structure:

• Introduction: Provides background information.
• Methods: Describes how the research was conducted.
• Results: Presents the findings.
• Conclusion: Summarizes the implications of the results.

Familiarizing yourself with this structure can help you locate information more efficiently during the exam. ??

Practice with Realistic Materials

To improve your skills, practice with materials that resemble those found in the IELTS. Here are some useful resources:

• Online platforms like IELTS Liz and British Council offer sample reading passages.
• Books specifically designed for IELTS preparation, such as Cambridge IELTS series.
• Scientific articles from reputable journals or websites like National Geographic or BBC Science.

Engaging with these texts will not only enhance your reading skills but also expand your vocabulary related to scientific topics. ??

Vocabulary Building

A strong vocabulary is crucial for success in the IELTS Reading section. Here are some strategies to build your scientific vocabulary:

• Create a glossary of common scientific terms you encounter.
• Use flashcards to memorize definitions and example sentences.
• Practice using new words in context by writing short paragraphs or discussing them with peers.

For instance, if you come across the word “photosynthesis”, make sure you understand its meaning and can use it in a sentence. ??

Time Management Skills

During the IELTS exam, time management is crucial. You have 60 minutes to read three passages and answer 40 questions. Here are some tips to manage your time effectively:

• Spend no more than 20 minutes on each passage.
• Skim the passage first to get a general idea before diving into the questions.
• Highlight key information and keywords while reading.

Practicing under timed conditions can help you become comfortable with the pace required during the actual test. ?

Sample Questions

Here are some types of questions you might encounter related to science passages:

• Multiple Choice: Choose the correct answer based on the passage.
• True/False/Not Given: Determine the accuracy of statements based on the text.
• Matching Headings: Match headings to the appropriate paragraphs.

Practicing these question types will help you become familiar with the format and improve your answering techniques. ??

Reference Answers

After practicing with sample questions, always check your answers against reference answers. This will help you identify areas for improvement and understand your mistakes. Consider using resources like IELTS Simon for detailed explanations. ??

By incorporating these strategies into your study routine, you will be better prepared to tackle the science reading materials in the IELTS exam. Remember, consistent practice and exposure to relevant texts are key to achieving a higher score. Good luck! ??