海
Sea

context: zh_tw: 儘管火星擁有冰蓋且其他行星可能擁有海洋，但地球是已知唯一表面由液態水覆蓋的行星。地球上的水的來源尚不明確。從太空遙望，地球像是一顆 “藍色彈珠”，水以海洋、冰蓋和雲層等不同形態存在。地球上海水體積為 1,335,000,000 立方公里（320,000,000 立方英里），佔地球水資源約 97.2% 並覆蓋著地球 70％以上的表面，另有約 2.15% 的地球水資源以冰的形式存在，分佈於北冰洋海冰、南極洲冰冠和南冰洋海冰，以及世界各地的冰川和表層沉積物中。其餘約 0.65％的水資源組成了地下水或處在水迴圈的各個階段，包括人們在生活中所使用的淡水、空氣中的水蒸氣，慢慢地形成了雲層，雲層積累到一定厚度後產生雨或雪落到地表，形成湖泊和河流，最終流向大海。海洋佔據了地球如此大部份，以致於英國作家亞瑟・查理斯・克拉克曾記述「地球」（Earth）命名為「海球」（Ocean）會更好。研究水以及地球水迴圈的科學稱為水文學；而流體力學則探討水運動時的物理現象；最近對於海的研究稱作海洋學。其一開始是研究海流的流向，但目前其已涵蓋了廣泛且跨學科的主題，它的研究範疇包括探討海水的特性；研究海浪、潮汐，以及海流 ；測繪海岸線和海床；並對海洋生物進行研究。 研究海洋運動以及其力量的分支學科稱為物理海洋學。海洋生物學則負責研究棲息于海洋生態系統的生物，包括但不限於動植物。以上兩者皆受到化學海洋學的研究支援，它研究海洋內的化學元素和分子的表現：特別是研究二氧化碳在海水酸度增加中起了什麼作用，以及海洋在碳迴圈中所扮演的角色。海洋地理學研究海洋的形態和狀況，海洋地質學則為大陸漂移學說、地球的組合方式及其構造提供證據，並使沉降的過程弄清，這門學問所獲得的資料可用來協助人們研究火山作用和地震。
en: Earth is the only known planet with seas of liquid water on its surface, although Mars possesses ice caps and similar planets in other solar systems may have oceans. It is still unclear where Earth's water came from, but, seen from space, our planet appears as a "blue marble" of its various forms: oceans, ice caps, clouds. Earth's 1,335,000,000 cubic kilometers (320,000,000 cu mi) of sea contain about 97.2 percent of its known water and cover more than 70 percent of its surface. Another 2.15% of Earth's water is frozen, found in the sea ice covering the Arctic Ocean, the ice cap covering Antarctica and its adjacent seas, and various glaciers and surface deposits around the world. The remainder (about 0.65% of the whole) form underground reservoirs or various stages of the water cycle, containing the freshwater encountered and used by most terrestrial life: vapor in the air, the clouds it slowly forms, the rain falling from them, and the lakes and rivers spontaneously formed as its waters flow again and again to the sea. The sea's dominance of the planet is such that the British author Arthur C. Clarke once noted that "Earth" would have been better named "Ocean".The scientific study of water and Earth's water cycle is hydrology; hydrodynamics studies the physics of water in motion. The more recent study of the sea in particular is oceanography. This began as the study of the shape of the ocean's currents but has since expanded into a large and multidisciplinary field: it examines the properties of seawater; studies waves, tides, and currents; charts coastlines and maps the seabeds; and studies marine life. The subfield dealing with the sea's motion, its forces, and the forces acting upon it is known as physical oceanography. Marine biology (biological oceanography) studies the plants, animals, and other organisms inhabiting marine ecosystems. Both are informed by chemical oceanography, which studies the behavior of elements and molecules within the oceans: particularly, at the moment, the ocean's role in the carbon cycle and carbon dioxide's role in the increasing acidification of seawater. Marine and maritime geography charts the shape and shaping of the sea, while marine geology (geological oceanography) has provided evidence of continental drift and the composition and structure of the Earth, clarified the process of sedimentation, and assisted the study of volcanism and earthquakes.
qas: question: zh_tw: 地球表面有多少被水覆蓋
en: How much of the earths surface is covered in water
answers: zh_tw: text: 70％
en: text: 70 percent

context: zh_tw: 海水是弱鹼性的，在工業革命前它的 pH 約為 8.2。然而最近，人類活動使得大氣中二氧化碳含量持續增加；大約 30-40% 增加的 CO2 被海洋吸收，形成碳酸並透過一個被稱為海洋酸化的過程降低海水 pH（現已低於 8.1）。預計到 2100 年，海水 pH 可達 7.7 (這意味著氫離子濃度增加三倍)，這將是長達一個世紀的顯著變化。鈣是海洋生物骨骼系統的重要組成成分， 但是碳酸鈣在壓力的作用下會變得更加容易溶解，因此碳酸鹽貝殼和骨骼系統會在補償深度以下發生溶解。 同時，碳酸鈣也會在較低的 PH 值環境下變得更易溶解，因此海洋酸化可能會對具有石灰質外殼的海洋生物（例如牡蠣、蛤、海膽和珊瑚）有著深遠影響，因為他們形成外殼的能力將會減弱，碳酸鹽補償深度將更接近海面。受影響的浮游生物將包括被稱為 pteropod 的蝸牛樣軟體動物，以及被稱為鈣板金藻和有孔蟲門的藻類。所有這些都是食物鏈的重要組成部分，其數量的減少將產生重大後果。在熱帶地區，珊瑚可能會受到嚴重影響，因為它將更難構造其碳酸鈣骨架， 這將對其他珊瑚礁居民產生不利影響。在地球的地質史中，目前海洋酸化的速度似乎是空前的，這使得我們不清楚海洋生態系統能在多大程度上適應未來的變化。引起特別關注的是，海洋酸化同預期中氣候變暖和海洋缺氧事件的額外壓力的組合會如何影響海洋。
en: Seawater is slightly alkaline and had an average pH of about 8.2 over the past 300 million years. More recently, anthropogenic activities have steadily increased the carbon dioxide content of the atmosphere; about 30–40% of the added CO2 is absorbed by the oceans, forming carbonic acid and lowering the pH (now below 8.1) through a process called ocean acidification. The pH is expected to reach 7.7 (representing a 3-fold increase in hydrogen ion concentration) by the year 2100, which is a significant change in a century.One important element for the formation of skeletal material in marine animals is calcium, but calcium carbonate becomes more soluble with pressure, so carbonate shells and skeletons dissolve below its compensation depth. Calcium carbonate also becomes more soluble at lower pH, so ocean acidification is likely to have profound effects on marine organisms with calcareous shells, such as oysters, clams, sea urchins, and corals, because their ability to form shells will be reduced, and the carbonate compensation depth will rise closer to the sea surface. Affected planktonic organisms will include the snail-like molluscs known as pteropods, and single-celled algae called coccolithophorids and foraminifera. All of these are important parts of the food chain and a diminution in their numbers will have significant consequences. In tropical regions, corals are likely to be severely affected as it becomes more difficult to build their calcium carbonate skeletons, in turn adversely impacting other reef dwellers.The current rate of ocean chemistry change appears to be without precedent in Earth's geological history, making it unclear how well marine ecosystems will be able to adapt to the shifting conditions of the near future. Of particular concern is the manner in which the combination of acidification with the expected additional stressors of higher temperatures and lower oxygen levels will impact the seas.
qas: question: zh_tw: 海水的 pH 值是多少？
en: What is the pH of seawater?
answers: zh_tw: text: 8.2
en: text: 8.2