The Japanese word 海水 (kaisui) directly translates to 'seawater' or 'ocean water' in English. It refers to the salt water that makes up the oceans and seas. This term is quite common and straightforward, used in a variety of contexts when discussing bodies of water, marine life, or activities related to the sea.
- Usage
- People use 海水 when talking about swimming in the ocean, the composition of ocean water, marine ecosystems, or even when describing the salty taste of water from the sea. It's a fundamental term for anyone learning about Japan's geography, which is surrounded by the sea, or about marine science.
- Contexts
- You'll encounter 海水 in discussions about beaches, coastal areas, fishing, shipping, and environmental issues related to the oceans. It's also used in scientific studies analyzing water salinity, temperature, and chemical properties. For instance, a biologist might study how certain marine organisms adapt to 海水, or a meteorologist might discuss how 海水 temperature affects weather patterns. Even in everyday conversations, when someone mentions going to the beach or the sea, the water they are referring to is 海水.
この地域では、海水の温度が一年を通して比較的安定しています。
子供たちは、海水浴を楽しんでいました。
- Grammar
- 海水 (kaisui) is a noun. It functions as a subject, object, or part of a noun phrase in sentences. It does not change form for plurality or gender.
この海岸の海水は非常にきれいです。
Learning to use 海水 (kaisui) in sentences is essential for discussing marine environments and related activities. As a noun, it can function as the subject, object, or be modified by other words. Here are various sentence structures and examples to illustrate its usage:
- Subject of a Sentence
- When 海水 is the subject, it performs an action or has a state described. Often, it's accompanied by particles like は (wa) or が (ga).
海水は塩分濃度が高い。
Translation: Seawater has a high salt concentration.
- Object of a Sentence
- As an object, 海水 is acted upon. The particle を (o) is typically used.
船は海水の上を航行する。
Translation: The ship sails on the seawater.
- Part of a Noun Phrase
- 海水 can be part of a larger noun phrase, often modified by adjectives or other nouns using the particle の (no).
これは海水浴に最適な場所だ。
Translation: This is an ideal place for bathing in seawater.
海水魚の生態について学んだ。
Translation: I learned about the ecology of saltwater fish.
- Describing Conditions
- It can be used to describe the state or quality of the water.
今日の海水は少し冷たい。
Translation: The seawater today is a bit cold.
この地域では、海水が汚染されている。
Translation: The seawater in this area is polluted.
You'll hear 海水 (kaisui) in a variety of everyday and specific situations, reflecting Japan's close relationship with the sea. Here's where you're likely to encounter this word:
- At the Beach and Coastal Areas
- When people talk about swimming, surfing, or simply enjoying the coast, they will often refer to the water as 海水. For example, someone might say, 「今日は海水が温かいね。」 (Kyō wa kaisui ga atatakai ne. - The seawater is warm today, isn't it?).
- Marine Biology and Environmental Discussions
- In educational settings, documentaries, or news reports about the ocean, 海水 is used to discuss water quality, salinity, pollution, and the impact on marine life. A scientist might explain, 「海水のpHバランスが崩れている。」 (Kaisui no pH baransu ga kuzurete iru. - The pH balance of the seawater is disrupted).
- Fishing and Maritime Industries
- Fishermen, sailors, and those involved in related industries use 海水 when discussing conditions at sea, types of fish (e.g., 海水魚 - kaisui-gyo - saltwater fish), or the challenges of operating in the ocean environment.
- Travel and Tourism
- When promoting coastal resorts or discussing travel plans involving the sea, 海水浴 (kaisui-yoku - seawater bathing) is a common term. Brochures might mention, 「透明度の高い海水をお楽しみください。」 (Tōmeido no takai kaisui o o-tanoshimi kudasai. - Please enjoy the highly transparent seawater).
- Everyday Conversations
- Even in casual conversation, if someone is talking about a recent trip to the coast or planning a beach day, the word 海水 might naturally come up. For instance, 「夏になったら、海水浴に行きたいね。」 (Natsu ni nattara, kaisui-yoku ni ikitai ne. - When summer comes, I want to go seawater bathing).
ダイバーは海水の中を調査した。
While 海水 (kaisui) is a straightforward term, learners might occasionally make mistakes, often due to confusion with similar concepts or overgeneralization. Here are some common pitfalls to watch out for:
- Confusing with 淡水 (Tansui - Freshwater)
- The most common mistake is to confuse 海水 (kaisui) with 淡水 (tansui), which means freshwater. These are direct antonyms. Kaisui is salty water from the sea, while tansui is non-salty water found in rivers, lakes, and rain. Forgetting this distinction can lead to nonsensical statements, like talking about drinking 海水 or swimming in freshwater rivers with kaisui.
- Overuse of the word 'Water' without context
- Sometimes, learners might translate 'ocean water' too literally and simply use 水 (mizu - water) when 海水 is more appropriate. While 水 is a general term, kaisui specifically denotes the salty ocean water. For example, saying 「海の水」 (umi no mizu) is understandable but 海水 is the standard, more concise term.
- Incorrectly applying pluralization or verb conjugations
- Japanese nouns, including 海水, generally do not have plural forms. Learners might mistakenly try to add plural markers or conjugate verbs in ways that are not applicable to this noun. Kaisui refers to the substance itself, regardless of quantity.
- Using it for non-ocean water
- It's crucial to remember that 海水 specifically refers to the water of the sea or ocean. Using it to describe water from a swimming pool (unless it's a saltwater pool specifically designed to mimic ocean water) or other bodies of water would be incorrect.
誤：この川の水は海水でできている。
Incorrect: This river water is made of seawater.
正：この川の水は淡水である。
Correct: This river water is freshwater.
While 海水 (kaisui) is the standard term for seawater, there are other words and phrases that might be used in related contexts, or that serve as alternatives depending on the nuance you wish to convey.
- 海 (Umi)
- 海 (Umi) simply means 'sea' or 'ocean'. It refers to the body of water itself, rather than the water as a substance. You might say 「海へ行く」 (Umi e iku - to go to the sea), where the destination is the sea, and the water there is implicitly 海水.
- 海洋 (Kaiyō)
- 海洋 (Kaiyō) is a more formal or scientific term for 'ocean'. It's often used in contexts discussing the global ocean, oceanography, or large-scale marine phenomena. For example, 「海洋汚染」 (kaiyō osen - ocean pollution) or 「海洋生物学」 (kaiyō seibutsugaku - marine biology).
- 潮水 (Shiosui)
- 潮水 (Shiosui) also refers to seawater, but it can sometimes carry a nuance of 'tide water' or water affected by tides. It's less common in everyday speech than 海水 but might be encountered in more specific contexts related to coastal environments or traditional practices.
- 淡水 (Tansui)
- As mentioned in common mistakes, 淡水 (Tansui) is the direct antonym, meaning 'freshwater'. It's important to contrast 海水 with tansui to solidify understanding.
- 海辺の水 (Umibe no mizu)
- This phrase literally means 'water by the sea' or 'seaside water'. It's a descriptive phrase rather than a single word and might be used when the exact nature of the water (salty or not, depending on proximity to the sea) is less important than its location. However, in most cases, 海水 is the more precise and common term.
- 泳ぐための水 (Oyo-gu tame no mizu)
- This translates to 'water for swimming'. While this could refer to 海水 in the ocean, it could also refer to water in a swimming pool or a lake. It's a functional description rather than a specific term for seawater.
海は広い。しかし、海水は塩辛い。
Translation: The sea is vast. However, the seawater is salty.
レベル別の例文
海の水はしょっぱい。
The sea's water is salty.
海 (umi) means sea. 水 (mizu) means water. しょっぱい (shoppai) means salty.
夏は海に行きたい。
In summer, I want to go to the sea.
夏 (natsu) means summer. 行きたい (ikitai) means want to go.
これは海のにおい。
This is the smell of the sea.
におい (nioi) means smell.
魚が海にいる。
Fish are in the sea.
魚 (sakana) means fish. いる (iru) means to be/exist (for animate things).
船が海を渡る。
A ship crosses the sea.
船 (fune) means ship. 渡る (wataru) means to cross.
海は青い。
The sea is blue.
青い (aoi) means blue.
子供が海で遊ぶ。
A child plays in the sea.
子供 (kodomo) means child. 遊ぶ (asobu) means to play.
海は広い。
The sea is wide/vast.
広い (hiroi) means wide/spacious.
この海水はとてもきれいです。
This seawater is very clean.
This sentence uses 海水 (kaisui) for seawater. きれい (kirei) means clean/beautiful.
夏に海水浴に行きました。
I went for a swim in the sea in the summer.
海水浴 (kaisui-yoku) is a compound word meaning 'seawater bathing' or swimming in the sea. 行きました (ikimashita) is the past tense of 'to go'.
塩分が多いため、海水は飲めません。
Because the salt content is high, seawater cannot be drunk.
塩分 (enbun) means salt content. 多いため (tame) means because. 飲めません (nemasen) is the negative potential form of 'to drink', meaning 'cannot drink'.
この地域では海水の温度が低いです。
The temperature of the seawater in this region is low.
温度 (ondo) means temperature. 低い (hikui) means low.
船は海水の上をゆっくり進む。
The ship slowly proceeds on the seawater.
ゆっくり (yukkuri) means slowly. 進む (susumu) means to proceed/advance.
多くの魚が海水に生息している。
Many fish inhabit the seawater.
多く (ooku) means many. 生息する (seisoku suru) means to inhabit/live.
子供たちは海水で遊ぶのが大好きだ。
Children love to play in the seawater.
大好きだ (daisuki da) means love/like very much.
この海岸の海水は透明度が高い。
The seawater at this coast has high transparency.
透明度 (tōmeido) means transparency. 高い (takai) means high.
ダイバーは海水中の酸素濃度を測定した。
The diver measured the oxygen concentration in the seawater.
ダイバー (daibā) means diver. 酸素濃度 (sanso nōdo) means oxygen concentration. 測定する (sokutei suru) means to measure.
夏季には多くの観光客が海水浴を楽しむために訪れる。
In the summer, many tourists visit to enjoy seawater bathing.
夏季 (kaki) means summer season. 観光客 (kankōkyaku) means tourist. 訪れる (otozureru) means to visit.
この地域の海水には独特のミネラル成分が含まれている。
The seawater in this region contains unique mineral components.
独特の (dokutoku no) means unique. ミネラル成分 (mineraru seibun) means mineral components. 含まれている (fukumarete iru) means to be included/contained.
環境保護のため、海水への化学物質の排出を厳しく規制している。
For environmental protection, the discharge of chemical substances into the seawater is strictly regulated.
環境保護 (kankyō hogo) means environmental protection. 化学物質 (kagaku busshitsu) means chemical substances. 排出 (haishutsu) means discharge/emission. 規制する (kisei suru) means to regulate.
沿岸部の住民は、海水の汚染が漁業に与える影響を懸念している。
Coastal residents are concerned about the impact of seawater pollution on fisheries.
沿岸部 (enganbu) means coastal area. 住民 (jūmin) means residents. 汚染 (osen) means pollution. 漁業 (gyogyō) means fisheries. 懸念する (kenen suru) means to be concerned.
この実験では、海水の蒸発による塩の結晶化を観察した。
In this experiment, the crystallization of salt due to seawater evaporation was observed.
実験 (jikken) means experiment. 蒸発 (jōhatsu) means evaporation. 結晶化 (kesshōka) means crystallization. 観察する (kansatsu suru) means to observe.
地球温暖化は海水温の上昇を引き起こしている。
Global warming is causing an increase in seawater temperature.
地球温暖化 (chikyū ondanka) means global warming. 上昇 (jōshō) means rise/increase. 引き起こす (hikiokosu) means to cause.
船の航行には、海水の深さが十分にあることが不可欠である。
Sufficient seawater depth is essential for ship navigation.
航行 (kōkō) means navigation. 十分 (jūbun) means sufficient. 深さ (fukasa) means depth. 不可欠 (fukaketsu) means essential/indispensable.
海洋生物は、海水の塩分濃度の変化に高度に適応している。
Marine organisms are highly adapted to changes in seawater salinity.
海洋生物 (kaiyō seibutsu) means marine organisms. 塩分濃度 (enbun nōdo) means salinity concentration. 適応する (tekiō suru) means to adapt.
沿岸部の生態系は、海水温の上昇や海洋酸性化の影響を受けやすい。
Coastal ecosystems are susceptible to the effects of rising seawater temperatures and ocean acidification.
生態系 (seitaikei) means ecosystem. 海洋酸性化 (kaiyō sanseika) means ocean acidification. 影響を受ける (eikyō o ukeru) means to be affected. 受けやすい (ukeyasui) means susceptible.
この研究では、海水中の微量元素の分布と海洋循環との関連性を調査した。
This study investigated the distribution of trace elements in seawater and their relationship with ocean circulation.
微量元素 (biryō genso) means trace elements. 分布 (bunpu) means distribution. 海洋循環 (kaiyō junkan) means ocean circulation. 関連性 (kanrensei) means relationship/correlation. 調査する (chōsa suru) means to investigate.
近年、異常気象による海水温の急激な変動が観測されている。
In recent years, rapid fluctuations in seawater temperature due to extreme weather have been observed.
近年 (kinnen) means in recent years. 異常気象 (ijō kishō) means extreme weather. 急激な (kyūgeki na) means rapid/sudden. 変動 (hendō) means fluctuation. 観測される (kansoku sareru) means to be observed.
船舶からの油流出は、海水の広範囲にわたる汚染を引き起こし、生態系に壊滅的な被害を与える。
Oil spills from ships cause widespread seawater pollution and inflict catastrophic damage on ecosystems.
船舶 (senpaku) means ships. 油流出 (abiyu rushutsu) means oil spill. 広範囲 (kōhan'i) means widespread. 壊滅的 (kaimetsuteki) means catastrophic. 被害を与える (higai o ataeru) means to inflict damage.
淡水化プラントは、海水から飲料水を生成する技術として重要性を増している。
Desalination plants are increasingly important as a technology for producing drinking water from seawater.
淡水化プラント (tansui-ka puranto) means desalination plant. 飲料水 (inryōsui) means drinking water. 生成する (seisei suru) means to produce/generate. 重要性 (jūyōsei) means importance.
海底火山活動は、海水の化学組成に一時的な変化をもたらすことがある。
Submarine volcanic activity can cause temporary changes in the chemical composition of seawater.
海底火山活動 (kaitei kazan katsudō) means submarine volcanic activity. 化学組成 (kagaku sosō) means chemical composition. 一時的な (ichijiteki na) means temporary. もたらす (motarasu) means to bring about/cause.
この地域の海水は、特定のプランクトンの大量発生に適した栄養塩濃度を示している。
The seawater in this region exhibits nutrient concentrations suitable for the mass proliferation of certain plankton.
特定 (tokutei) means specific. プランクトン (purankuton) means plankton. 大量発生 (tairyō hassei) means mass proliferation. 適した (tekishita) means suitable. 栄養塩濃度 (eiyōen nōdo) means nutrient concentration. 示す (shimesu) means to show/indicate.
海洋循環モデルは、海水の熱輸送能力と地球の気候システムにおけるその役割をシミュレーションする。
Ocean circulation models simulate the heat transport capacity of seawater and its role in the Earth's climate system.
海洋循環モデル (kaiyō junkan moderu) means ocean circulation model. 熱輸送能力 (netsu yusō nōryoku) means heat transport capacity. 気候システム (kikō shisutemu) means climate system. シミュレーションする (shimyurēshon suru) means to simulate.
地球規模での海水温の上昇は、サンゴ礁の白化現象を加速させ、海洋生態系の脆弱性を露呈している。
The global rise in seawater temperature is accelerating coral reef bleaching events, exposing the vulnerability of marine ecosystems.
地球規模 (chikyū kibo) means global scale. サンゴ礁 (sangoshō) means coral reef. 白化現象 (hakkashō genshō) means bleaching event. 加速させる (kasoku saseru) means to accelerate. 脆弱性 (zeijakusei) means vulnerability. 露呈する (rotei suru) means to expose.
深海掘削プロジェクトは、海水が地下深部でどのように化学的・物理的変化を遂げるのかについての貴重な洞察を提供している。
Deep-sea drilling projects are providing valuable insights into how seawater undergoes chemical and physical transformations in the deep subsurface.
深海掘削 (shinkai kussaku) means deep-sea drilling. 地下深部 (chika shinbu) means deep subsurface. 遂げる (tōgeru) means to undergo/achieve. 貴重な (kichō na) means valuable. 洞察 (dōsatsu) means insight.
海洋酸性化の進行は、炭酸カルシウムの殻を持つ海洋生物の骨格形成を阻害し、食物連鎖全体に影響を及ぼす可能性がある。
The progression of ocean acidification may inhibit the skeletal formation of marine organisms with calcium carbonate shells, potentially affecting the entire food chain.
進行 (shinkō) means progression. 炭酸カルシウム (tansan karushiumu) means calcium carbonate. 殻 (kara) means shell. 骨格形成 (kokkaku keisei) means skeletal formation. 阻害する (sogai suru) means to inhibit. 食物連鎖 (shokumotsu rensa) means food chain. 及ぼす (oyobosu) means to exert/affect.
沿岸域における人間活動の増加は、海水の富栄養化を招き、デッドゾーンの拡大を助長している。
Increased human activity in coastal areas leads to eutrophication of seawater, promoting the expansion of dead zones.
沿岸域 (engan'iki) means coastal zone. 人間活動 (ningen katsudō) means human activity. 富栄養化 (fu-eiyōka) means eutrophication. 招く (maneku) means to invite/lead to. デッドゾーン (deddo zōn) means dead zone. 拡大 (kakudai) means expansion. 助長する (jochō suru) means to promote/foster.
氷床の融解によって放出される大量の淡水は、局所的な海水の塩分濃度に影響を与え、海洋大循環のパターンを変化させる懸念がある。
The large influx of freshwater released by melting ice sheets affects local seawater salinity and raises concerns about altering patterns of thermohaline circulation.
氷床 (hyōshō) means ice sheet. 融解 (yūkai) means melting. 放出される (hōshutsu sareru) means to be released. 淡水 (tansui) means freshwater. 局所的 (kyokusho teki) means local. 塩分濃度 (enbun nōdo) means salinity. 海洋大循環 (kaiyō dai junkan) means thermohaline circulation/large-scale ocean circulation. 懸念 (kenen) means concern.
海水中のマイクロプラスチック汚染は、食物網を通じて生物濃縮され、生態系全体に広範な健康被害をもたらすリスクがある。
Microplastic pollution in seawater bioaccumulates through the food web, posing a risk of widespread health impacts across the ecosystem.
マイクロプラスチック (maikuropurasuchikku) means microplastic. 汚染 (osen) means pollution. 食物網 (shokumotsu-mō) means food web. 生物濃縮 (seibutsu nōshuku) means bioaccumulation. 広範な (kōhan na) means widespread. 健康被害 (kenkō higai) means health damage/impact. もたらす (motarasu) means to bring about.
海洋地質学者は、海水と海底堆積物の相互作用が、地球の過去の気候変動を解明する鍵となると考えている。
Marine geologists believe the interaction between seawater and seafloor sediments holds the key to deciphering Earth's past climate fluctuations.
海洋地質学者 (kaiyō chishitsu gakusha) means marine geologist. 海底堆積物 (kaitei taisetsubutsu) means seafloor sediments. 相互作用 (sōgo sayō) means interaction. 解明する (kaimei suru) means to decipher/clarify. 鍵 (kagi) means key.
極域における海水の熱的・塩分濃度の特性は、地球規模の海洋循環システムに不可欠な駆動力を提供している。
The thermal and haline properties of seawater in polar regions provide essential driving forces for the global ocean circulation system.
極域 (kyoku'iki) means polar regions. 熱的 (netsuteki) means thermal. 塩分濃度 (enbun nōdo) means salinity. 特性 (tokusei) means properties. 駆動 (kudō) means drive/driving force. 提供する (teikyō suru) means to provide.
海洋生物地球化学的プロセスは、海水の炭素循環における役割を理解する上で極めて重要であり、気候変動緩和策の立案に貢献する。
Marine biogeochemical processes are critically important for understanding the role of seawater in the carbon cycle and contribute to the formulation of climate change mitigation strategies.
生物地球化学的 (seibutsu chikyū kagaku teki) means biogeochemical. プロセス (purosesu) means process. 炭素循環 (tanso junkan) means carbon cycle. 極めて (kiwamete) means extremely/critically. 理解する上で (rikai suru ue de) means in understanding. 緩和策 (kanwa saku) means mitigation strategy. 立案 (ritsuan) means formulation.
地中海における海水の熱的成層と水塊の混合は、複雑な水文学的パターンを形成し、沿岸生態系に影響を与える。
The thermal stratification and water mass mixing in the Mediterranean Sea form complex hydrological patterns, impacting coastal ecosystems.
地中海 (chichūkai) means Mediterranean Sea. 熱的成層 (netsuteki seisō) means thermal stratification. 水塊 (suikai) means water mass. 混合 (kongō) means mixing. 水文学的 (suigakuteki) means hydrological. パターン (patān) means pattern. 形成する (keisei suru) means to form.
地球の気候システムにおける海水の熱容量の大きさは、気温の急激な変動を緩和する上で決定的な役割を果たしている。
The immense heat capacity of seawater in Earth's climate system plays a decisive role in moderating rapid temperature fluctuations.
熱容量 (netsuyōryō) means heat capacity. 大きさ (ōkisa) means size/magnitude. 気温 (kion) means temperature. 急激な (kyūgeki na) means rapid. 緩和する (kanwa suru) means to moderate/alleviate. 決定的な (ketteiteki na) means decisive. 役割を果たす (yakuwari o hatasu) means to play a role.
深海熱水噴出孔周辺の海水は、独特の化学組成を持ち、地球外生命探査のモデルとしても注目されている。
The seawater surrounding deep-sea hydrothermal vents possesses a unique chemical composition and is also of interest as a model for extraterrestrial life exploration.
深海熱水噴出孔 (shinkai nessui funshutsukō) means deep-sea hydrothermal vent. 独特の (dokutoku no) means unique. 地球外生命 (chikyūgai seimei) means extraterrestrial life. 探査 (tansa) means exploration. モデル (moderu) means model. 注目されている (chūmoku sarete iru) means to be noted/attracting attention.
海洋表層の海水のpH値の低下は、炭酸カルシウム骨格を持つ生物の生存を脅かし、広範な生態系への影響が懸念される。
The decrease in pH of surface seawater threatens the survival of organisms with calcium carbonate skeletons, raising concerns about widespread ecological impacts.
表層 (hyōsō) means surface layer. pH値 (pH chi) means pH value. 低下 (teika) means decrease. 脅かす (obiyakasu) means to threaten. 生存 (seizon) means survival. 広範な (kōhan na) means widespread. 懸念される (kenen sareru) means to be concerned.
大気中の二酸化炭素濃度の増加は、海水による吸収を介して海洋酸性化を進行させ、海洋生物の生理機能に多大な影響を与えている。
The increase in atmospheric carbon dioxide concentration drives ocean acidification through absorption by seawater, significantly impacting the physiological functions of marine life.
大気中 (taikichū) means in the atmosphere. 二酸化炭素 (nisanka tanso) means carbon dioxide. 吸収 (kyūshū) means absorption. 介して (kaishite) means through/via. 進行させる (shinkō saseru) means to drive/advance. 生理機能 (seiri kinō) means physiological function. 多大な (tadai na) means significant/great.
過去数百万年にわたる海水の同位体組成の変動は、古海洋学的な研究において地球の気候変動史を解明する上で不可欠な情報源となっている。
Variations in the isotopic composition of seawater over the past several million years serve as an indispensable source of information for deciphering Earth's climate change history in paleoceanographic research.
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