自然界中水的化学英文版
自然界的水知识点总结
第三单元《自然界的水》知识点一、水1、水的组成：（1）电解水的实验A.装置―――水电解器B.电源种类---直流电C.----增强水的导电性D.2↑+ O 2↑产生位置 负极 正极体积比 2 ：1质量比 1 ：8F.检验：O 2---出气口置一根带火星的木条----木条复燃H 2---出气口置一根燃着的木条------气体燃烧，产生淡蓝色的火焰（2）结论： ①水是由氢、氧元素组成的。
②一个水分子是由2个氢原子和1个氧原子构成的。
③化学变化中，分子可分而原子不可分。
例：根据水的化学式H 2O ，你能读到的信息化学式的含义 H 2O①表示一种物质 水这种物质②表示这种物质的组成 水是由氢元素和氧元素组成的 ③表示这种物质的一个分子 一个水分子④表示这种物质的一个分子的构成 一个水分子是由两个氢原子和一个氧原子构成的2、水的化学性质（1）通电分解2↑+O 2↑（2）水可遇某些氧化物反应生成碱（可溶性碱），例如：H 2O + CaO==Ca(OH)2（3）水可遇某些氧化物反应生成酸，例如：H 2O + CO 2==H 2CO 33、水的污染：（1）水资源A ．地球表面71%被水覆盖，但供人类利用的淡水小于 1%B ．海洋是地球上最大的储水库。
海水中含有80多种元素。
海水中含量最多的物质是 H 2O ，最多的金属元素是 Na ，最多的元素是 O 。
C ．我国水资源的状况分布不均，人均量少 。
（2）水污染A 、水污染物：工业“三废”（废渣、废液、废气）；农药、化肥的不合理施用生活污水的任意排放 B 、防止水污染：工业三废要经处理达标排放、提倡零排放；生活污水要集中处理达标排放、提倡零排放；合理施用农药、化肥，提倡使用农家肥；加强水质监测。
（3）爱护水资源：节约用水，防止水体污染4、水的净化（1）水的净化效果由低到高的是 静置、吸附、过滤、蒸馏（均为 物理 方法），其中净化效果最好的操作是 蒸馏；既有过滤作用又有吸附作用的净水剂是活性炭。
2水环境化学简化版
1
水圈循环
水的特性和水分子结构
天然水系的类别
天然水体中化学物质的存在形态
天然水体中的异相物质
2
水（water）是组成自然界最重要的物质之一，是一切生物生存必不可
少的物质条件，对地球表层环境的形成和改造起到重要作用。
2～9mg/L，所以是水中微生物的一个重要活动场所，每毫升水
中可含108个细菌个体。 作为水体的另一个重要组成部分，在底层的沉积物中含有各种
颗粒度不等的砾、砂、粘土、淤泥、生物的排泄物和尸体以及
各种天然和人造的化学物质（金属、颗粒状有机物等）。
19
在占极大体积比率的中间层中所含的杂质主要是溶解性的分子和
24
用公式表示为：
［A(aq)］=KHA PA
式中,A—某种气体在液相中的溶解度，mol/L； PA—气体分压,Pa或atm； KHA—亨利系数，在一定温度下KHA是常数,
mol/L. Pa或mol/L.atm。
天然水体中一些重要无机气体的亨利常数列于表3。
25
表3 25℃时天然水体中一些重要无机气体的亨利常数
9
表1 水的某些异常性质以及意义
10
天然水系的类别
各种类别的天然水系
11
重要的天然水系
海
洋
河
湖
流
泊
降
水
地 下水
12
天然水体中化学物质的存在形态
化学物质在环境中有一定的赋存形态。广而言之，“形态”
一词含义包括物理结合状态、化学态（有机的或无机的）、
价态、化合态和化学异构态等多方面（元素的有机化合物形态没有包含在内）。
初中化学自然界的水知识点归纳
初中化学自然界的水知识点归纳水是地球上最常见的物质之一，也是人类生命所必需的。
化学中，水是一种无机物质，由氢和氧原子组成。
初中化学中，水是一门重要的学科，本文将对初中化学中关于自然界的水方面的知识点进行归纳和总结。
水的性质物理性质•无色、无味、无臭：在常温下，水是一种无色、无味、无臭的液体。
•密度大：水在4℃时密度最大，为1.0 g/cm³，而在0℃时密度为0.917 g/cm³。
•熔点和沸点高：水的熔点为0℃，沸点为100℃。
相比较其他同类分子来说，水的熔点和沸点都相对较高。
•具有高粘度：水的黏度大，易使一些细小的物质溶解在水中，不易挥发。
化学性质•酸碱性质：水有弱的酸碱性质。
纯水的pH值为7，为中性溶液，如果加入弱酸或弱碱，它的酸碱性质会发生变化。
•具有溶解性和氧化性：水具有很高的溶解性和一定的氧化性。
在生物体内具有缓冲作用，可与物质发生氧化反应，如生物中的呼吸作用。
水的自然界分布地球上的水全球水分布不平衡，一般分为地表水和地下水两种。
•地表水：地表水是指地表上凝聚成为湖、河、湿地等的水，也包括地球表面的雪、冰川融水等。
地表水是人们生产和生活中重要的水源。
•地下水：地下水指地下深处含水岩石层中的地下水体，地下水是一个重要的水资源，也是地表水补给的重要来源。
生物体内的水水是维持生物体生命活动的一种重要物质，在人和其他生物体内部都有分布，例如：•人体内的水：成年人平均体内水分含量为60-70%。
人体内的水分为细胞内液、细胞外液和血浆等。
•植物体内的水：植物的水分主要在细胞膜内，它是植物生长发育的重要条件之一。
植物根部吸收土壤中的水分，通过导管输送到各个部位。
水的循环水的循环过程地球上的水不断地进行循环，这是一个循环过程，称为水循环。
水循环可以分为3个阶段：•蒸发（蒸发和升华）：水面上和陆地上的水受到太阳的照射，导致水分子渐渐蒸发到空气中，并以水汽的形式升到高空。
•降水（凝结和降水）：大气中的水汽发生凝结，形成云，云的水滴或冰晶或雨滴成为降水，返回地面。
4.1水资源及其利用第1课时课件+2024-2025学年化学人教版九年级上册
A．降温结晶
B．絮凝沉降
C．杀菌消毒
D．细沙滤水
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9．
《天工开物》中详细记载了明代造竹纸的过程。下列造纸的主
要步骤中，属于过滤操作的是( C)
A．斩竹漂塘：将竹竿截断成五至七尺长，放入池塘中浸沤
B．煮楻足火：用石灰浆涂在竹纤维上，放入桶中蒸煮
C．荡料入帘：用竹帘从纸浆中“捞纸”
D．透火焙干：将刚生产出的湿纸张贴在烧火的墙上烤干
人工湿地作为一种生态修复技术，可以实现净化污水与增强景观效果的双 重目的，是一种经济有效的污水处理新技术，被誉为“污水处理的革命”。
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(1)人工湿地中植物根系所起的作用是__能__够__吸__收__污__水__中__的__营__养__物__质__(或__富___
_集__某__些__有__害__物__质__，__为__根__区__好__氧__微__生__物__输__送__氧__气__)__(写出一条即可)。
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6．“南水北调”工程是我国水利史上一大壮举，缓解了华北地区缺水的 局面以及缺水对发展的制约。为保护南水北调饮用水水源，下列做法合理 的是( D) A．南方工厂将工业废水直接排放进水库 B．沿途耕地禁止施用农药、化肥 C．北方农田全部采用大水漫灌 D．加强沿途水质监测、监控，确保水质安全
基质
植物
除氮效果 除磷效果
沸石 较好 差
砾石 差 较好
黄沙 差 差
煤灰渣 较好 较好
芦苇 差
极强
香蒲 极强
差
菖蒲 差
极强
灯芯草 极强 极强
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Chapter 1 水分析化学英文课件
Example：Two objects were weighed to be 1.6380 g and 0.1637 g, respectively. It is supposed that the true weights for them are 1.6381 g and 0.1636 g. Please give out the corresponding absol ute vales and relative values. E = 1.6380 g – 1.6381 g = -0.0001 g Absolute value: E = 0.1637 g - 0.1636 g = 0.0001 g Er = -0.0001/1.6381×100% = -0.006% Er = 0.0001/0.1638×100% = 0.06%
IV :industrial water, and entrainment water V :agricultrial water, and landscapewater
1.5
Error
Data analysis
Error is the difference between true value and determined value.
During the cycling process, impurities such as heavy metals, toxic organic chemicals, compounds, carbon dioxide, bacterials, humus, protein, sand, algae, and mud can be dissolved and involved in the water.
Uncertainty means the amount by which a measured value deviates from the true value.
化学式中水的英语
化学式中水的英语Water in Chemical FormulasWater is a ubiquitous and essential compound found in various forms throughout the natural world. Its chemical formula, H2O, is one of the most widely recognized and understood representations of a chemical substance. In this essay, we will delve into the significance of water's chemical formula and explore its importance in various scientific and everyday contexts.The chemical formula H2O represents the molecular structure of water, which consists of two hydrogen atoms covalently bonded to a single oxygen atom. This simple yet elegant arrangement gives rise to the unique properties and behaviors of water that are crucial to life on Earth. The two hydrogen atoms are positioned at an angle of approximately 104.5 degrees relative to the oxygen atom, forming a bent molecular structure.The polarity of the water molecule is a fundamental characteristic that contributes to its remarkable properties. The unequal sharing of electrons between the hydrogen and oxygen atoms results in a partial positive charge on the hydrogen atoms and a partial negativecharge on the oxygen atom. This polarity allows water molecules to form hydrogen bonds with each other, creating a network of interconnected molecules that gives rise to water's high surface tension, cohesion, and ability to act as a universal solvent.The chemical formula H2O also highlights the composition of water, which is two parts hydrogen and one part oxygen. This ratio is essential in understanding the stoichiometry, or the quantitative relationship between the reactants and products in chemical reactions involving water. The ability to accurately represent the composition of water through its chemical formula is crucial in fields such as chemistry, biology, and environmental science, where the precise quantification of water is necessary for various calculations and analyses.In the context of chemistry, the water formula H2O is ubiquitous in chemical equations and reactions. Water is often a reactant, a product, or a solvent in many chemical processes, and its presence or absence can significantly impact the outcome of a reaction. The ability to correctly identify and balance the water molecules in a chemical equation is a fundamental skill for students and professionals in the field of chemistry.Furthermore, the water formula H2O is essential in understanding the phase changes of water, which are critical in various scientific andpractical applications. Water can exist in three main phases: solid (ice), liquid, and gas (water vapor). The phase of water is determined by the amount of energy (heat) present, and the chemical formulaH2O remains constant regardless of the phase. Understanding the phase changes of water, as represented by its formula, is crucial in fields such as meteorology, climatology, and engineering, where the behavior of water in its different states is of paramount importance.In the context of biology and biochemistry, the water formula H2O is central to the understanding of the role of water in living organisms. Water is the most abundant molecule in the human body, comprising approximately 60% of our total body weight. It plays a vital role in numerous physiological processes, such as cellular function, nutrient transport, waste removal, and temperature regulation. The ability to represent water accurately through its chemical formula is essential in understanding the intricate biochemical reactions and pathways that sustain life.Moreover, the water formula H2O is crucial in the field of environmental science and sustainability. Water is a precious natural resource, and its management and conservation are critical for human and ecological well-being. The chemical formula H2O allows for the precise quantification and tracking of water in the hydrological cycle, which includes the processes of evaporation, precipitation, and groundwater recharge. This understanding isessential for the development of effective water management strategies, environmental policies, and sustainable water use practices.In conclusion, the chemical formula H2O is a powerful and versatile representation of the water molecule, which is essential in various scientific and everyday contexts. Its simplicity belies the profound significance of water's molecular structure and the impact it has on the natural world, chemical processes, and the sustenance of life. Understanding the water formula H2O and its implications is a fundamental aspect of scientific literacy and a crucial tool for addressing the complex challenges facing our planet.。
h2o 英文化学名称
h2o 英文化学名称Water is an essential compound that is vital to sustaining life on our planet. Its chemical name, H2O, is a concise representation of its molecular structure consisting of two hydrogen atoms and one oxygen atom. This simple yet remarkable compound plays a crucial role in a vast array of biological, chemical, and physical processes that shape our world.At the molecular level, the unique arrangement of the hydrogen and oxygen atoms in the water molecule gives rise to its remarkable properties. The polar nature of the water molecule, with the oxygen atom carrying a partial negative charge and the hydrogen atoms carrying a partial positive charge, allows for the formation of hydrogen bonds between water molecules. These hydrogen bonds are responsible for water's high boiling point, surface tension, and ability to act as a universal solvent, dissolving a wide range of substances.The importance of water in living organisms cannot be overstated. Water makes up approximately 60% of the human body and isessential for maintaining cellular function, transporting nutrients and waste, regulating body temperature, and facilitating numerous biochemical reactions. Without water, life as we know it would not exist, as it is the medium in which many essential biological processes take place.In the natural world, the water cycle, also known as the hydrologic cycle, demonstrates the continuous movement of water through the Earth's atmosphere, land, and oceans. This cycle is driven by the Sun's energy, which evaporates water from the Earth's surface, leading to the formation of clouds and eventual precipitation, replenishing freshwater sources such as rivers, lakes, and groundwater. This continuous circulation of water is crucial for maintaining the balance of ecosystems and supporting the diverse range of life on our planet.Water also plays a vital role in various industrial and technological applications. It is used as a coolant in power plants, a solvent in chemical processes, and a raw material in the production of many consumer goods. The ability of water to conduct heat and electricity, as well as its unique properties, makes it an essential component in various industries, from energy production to pharmaceutical manufacturing.The availability and quality of water resources, however, are underincreasing pressure due to human activities such as industrialization, urbanization, and agricultural practices. Pollution, overexploitation, and the effects of climate change are all contributing to the depletion and degradation of water sources worldwide. Addressing these challenges and ensuring the sustainable management of water resources is a critical global issue that requires the collective effort of governments, industries, and individuals.In conclusion, the chemical name H2O represents a compound that is fundamental to life on Earth. From its molecular structure to its myriad applications, water's unique properties and its role in sustaining the natural world and human civilization make it an indispensable resource. As we continue to face the challenges of water scarcity and pollution, it is crucial that we recognize the importance of water and work towards the responsible and efficient use of this precious resource.。
水的来源和用途的英语作文
水的来源和用途的英语作文Water is essential for all living organisms on Earth. It is the source of life and without it, we would not be able to survive. 水是地球上所有生物所必需的。
它是生命的源泉，在没有水的情况下，我们将无法生存。
One of the main sources of water on Earth is through precipitation. This includes rain, snow, sleet, and hail. When precipitation falls tothe ground, it replenishes our water sources such as rivers, lakes, and oceans. 地球上水的主要来源之一是降水。
这包括雨水、雪、雨夹雪和冰雹。
当降水落到地面时，它会补充我们的水源，如河流、湖泊和海洋。
Another important source of water is groundwater. This is the water that is stored beneath the Earth's surface in layers of rock and soil. Groundwater can be accessed through wells and springs, providingus with a constant supply of fresh water. 另一个重要的水源是地下水。
这是存储在地球表面下岩石和土壤层中的水。
地下水可以通过井和泉水获取，为我们提供持续的淡水供应。
Water is used for a variety of purposes, including drinking, cooking, bathing, and cleaning. It is also essential for agriculture, industry, andgenerating electricity. 水被用于各种用途，包括饮用、烹饪、洗浴和清洁。
化学九年《自然界中的水》之三
？
分别加入肥皂水
蒸馏水
含氯化钙 的蒸馏水
二、水的净化
• 现象观察
➢蒸馏水中产生泡沫多；硬水中形成较多白 色垢状物。（此方法简单鉴别。）
二、水的净化
• 通过以上两个实验我们知道，有的看上去 澄清透明的水，其实含有杂质。
• 这种水作饮用水、生活用水、工业用水、 科研用水都是不利的。
• 下面我们来学习净化水的一些方法。
水 通电
氢气 + 氧气
水是有氢元素和氧元素组成
二、水的净净化化
• 这是生活中常见的一些水，它们都是纯净 物吗？都能直接饮用吗？
被污染 的河水
海水
自来水
矿泉水
蒸馏水
纯净水
二、水的净化
1。分别蒸干10mL蒸馏水和食盐水
实
验
演
示
蒸馏水 氯化钠溶液
（
动
画
）
二、水的净化
2。将肥皂水分别加入20mL蒸馏水和 含少量氯化钙的水（硬水）中
2．知道了水的组成及性质吗？ 复习巩固
（1）水的组成
实验：水的电解实验现象 ：
①．接通直流电源，看见两管子中都出现气泡， 负极和正极中气体的体积比大约为2∶1
②．将一根带火星的小木条放在电源正极，木条 复燃，说明生成了氧气
③．将一根燃着的木条放在电源负极处，气体被 点燃，产生淡蓝色火焰，用一个干冷的烧杯放在 火焰上方，烧杯内壁出现水珠，说明反应生成了 氢气
试管２中产生的气体能使带火星的木条复燃， 说明是氧气
２.用点燃的木条检验试管１中产生 的气体?
试管１产生的气体可以在空气 中燃烧，火焰颜色呈淡蓝色， 是氢气
推断水的组成元素
通过实验我们了解到：
An Analysis of the Chemical Properties of Water
An Analysis of the Chemical Propertiesof Water水的化学性质分析水是地球上常见的物质之一，被称为“生命之源”，它在生物和地球循环过程中扮演着重要的角色。
在许多方面，水都是一个特殊的物质，这归功于它独特的化学性质。
这篇文章将分析水的化学性质，以便更好地理解这个世界的运作。
1. 分子结构水是由氢原子和氧原子构成的化合物，其分子式为H2O。
氧原子和两个氢原子通过共价键相连，形成一个角度为104.5度的V型分子。
这是因为氧原子具有八个电子，其中六个外层电子处于孤对电子状态，带有负电荷。
这些孤对电子占据了氧原子分子轨道的空穴，推开了氢原子分子轨道，从而导致两个氢原子之间的角度加大。
2. 极性水分子是极性分子，这是因为氧原子的电负性比氢原子高得多。
因此，在H2O 分子中，氧原子带有强烈的负电荷，而氢原子则带有弱的正电荷。
这导致了H2O分子中部分正电荷和部分负电荷的分离，即所谓的“极性”。
这种极性分子相互作用使得水分子表现出多种独特的化学性质。
3. 溶剂性由于水分子的极性，水是一种优秀的溶剂。
水中的极性分子（如化合物）与水分子中的部分分离电荷形成氢键，这使得溶质能够溶解在水中。
此外，水分子本身也具有一定的离子性。
当水分子解离成氢离子（H+）和氢氧根离子（OH-）时，这些离子依靠氢键相互吸引在一起，形成了亲水层。
这个亲水层可以将离子化合物分解成离子，并促进离子化合物的溶解。
4. 相变热水的相变热包括了液体-气体相变和液体-固体相变。
液体-气体相变需要大量的热量，通常称为蒸发。
相反，水的液体-固体相变则产生少量的热量，通常称为冻结。
这是因为在液体-气体相变中，水分子必须抵抗表面张力和与周围气体的空气压力。
因此，它需要吸收热量才能蒸发。
对于液体-固体相变而言，则是因为分子动能的下降所导致的，当水分子变得更接近时，它们形成了氢键，这吸收了少量的热量。
5. 密度水在4度时具有最大密度，也就是说，水在4度时最重。
The Chemistry of Water and Its Applications
The Chemistry of Water and ItsApplications水是一种无色、无味、无臭的液体，是地球上最为普遍的物质之一。
几乎所有生命体系都依赖于水来存活。
在化学科学中，水也是一个非常重要的研究对象。
本文将探讨水的化学特性以及一些水在生活和科学中的应用。
一、水的化学特性1. 水的分子结构水分子由两个氢原子和一个氧原子组成。
在分子中，氧原子接受了两个氢原子的电子，形成了两根O-H键。
这些键的极性使得水分子具有一定的电荷，这也解释了为什么水能够成为一个非常好的溶剂。
2. 水的极性由于水分子中极性的原因，水能够溶解许多离子和分子。
极性的原因在于，水分子中的氧原子带有一定的负电荷，而氢原子带有一定的正电荷。
这导致水分子的电子云分布不均匀，形成了一个极性分子。
3. 水的凝固和熔化水具有非常特殊的凝固和熔化性质。
正常情况下，物质的熔化和凝固点可以通过温度来控制。
但是对于水而言，当它从液态水变成冰时，它的密度会发生相反的变化。
这是由于水分子在冰中排列成了一种对称分子结构，使得冰的密度比液态水低。
这种特性非常重要，因为它导致了水的维持温度比其他液体更加稳定，从而保护了地球上的大多数生命。
4. 水的氢离子浓度水的氢离子浓度决定了它的酸碱性质。
水中的氢离子浓度越高，它就越酸性。
水一般被认为是中性的，它的pH值为7。
当水的氢离子浓度高于7时，它就成为了一种酸性物质，当氢离子浓度低于7时，它就成为了一种碱性物质。
二、水的应用1. 水的生物学作用水对生命是至关重要的。
人类身体中的大约60%是水。
它是我们的细胞、器官和组织的基本成分，帮助传递营养物质和荷尔蒙，并维持我们的体温。
水同样也对植物生长非常重要，照料植物的水和营养是植物成长的两个关键因素。
2. 水的化学反应水可以参与许多化学反应。
在许多有机反应中，水往往是充当反应产物或是催化物质。
水也可以在许多工程和生化反应中用作工艺剂或反应介质。
例如，水可以被用作热泵中的传热介质，也可以在许多化工工艺中作为反应介质。
九年级化学自然界中的水1
九年级化学自然界中的水1
人的一生难免会遇到各类大大小小的困难或不幸，但是只要心怀感恩，那么所有的困难都只是为了成就我们的坚强而来的……
就以午后去市里理个发，因市里街道大修路，一个人步行从街东拐到街北，又从路东辗转到路西，再横穿紫金街的大土马路，可谓是满面风尘，两脚黄土。坑坑洼洼，磕磕绊绊自不必说，幸运的是 终于找到那家老店，请师傅给我理了个不Байду номын сангаас的发型。当然应该是自认为脸型好随便剪都好看的缘故吧！
礼拜五快下班的时候，美梦告诉我，明天他要去跟心爱的女孩子说“我爱你”了，不知道她会不会同意。我说肯定没问题，只要你有足够的勇气。然后美梦告诉我，那个女孩曾经是他的邻居，彼此 有好感，明天他打算去验证一下。我知道现在的印度，年轻人的结合主要还是父母之命，然后就问他，这也是你父母的意思吗？他说不是，现在只是谈恋爱，这个女孩的年龄才18岁，还是个在校的学生。 我不禁对他刮目相看，说起自己二十好几的时候，还像头孤独的野狼一样，只知道对月嚎叫，大家就都哈哈大笑起来。悉尼娱乐场真人
水的化学式英语
水的化学式英语Introduction:Water is an essential compound that is vital for the sustenance of life. It is a tasteless, odorless, andcolorless liquid that is made up of two elements, hydrogen and oxygen.The Chemical Formula of Water:The chemical formula of water is H2O, which signifies that it is composed of two atoms of hydrogen and one atom of oxygen. The atomic number of hydrogen is one, while that of oxygen is eight. This means that water has a molecular weight of 18.Bonding in Water:Water molecules are formed through covalent bonding, which occurs when atoms of different elements share electrons. In water, hydrogen and oxygen atoms share electrons, making the molecule stable and highly cohesive.Physical Properties of Water:Water is a unique substance with several unique physical properties, including:1. High surface tension: Water molecules are cohesive, which leads to the formation of hydrogen bonds between them. This results in high surface tension, which enables water to resist rupture when subjected to external pressure.2. High boiling point: Water has a high boiling point of 100 degrees Celsius, which makes it an excellent solvent and an ideal medium for chemical reactions.3. High specific heat capacity: Water has a highspecific heat capacity, meaning that it can absorb and storehigh amounts of heat energy.4. Density: Water is an anomaly in that its density increases as its temperature drops until it reaches 4 degrees Celsius. At this point, the density of water starts to decrease as it transforms into ice.Uses of Water:Water has several uses, including:1. Drinking: Water is essential for hydration and is necessary for the proper functioning of the body.2. Agriculture: Water is used for irrigation, which plays a crucial role in food production.3. Manufacturing: Water is used in various industrial processes, such as cooling and heating.Conclusion:In conclusion, water is a vital substance that is essential for the survival of all living organisms. Its chemical formula, H2O, signifies that it is made up of two atoms of hydrogen and one atom of oxygen, and its unique physical properties make it an excellent solvent and a necessary component in several industrial processes.。
水化学英语
水化学英语Water chemistry is an important area of study that looks at the chemical properties and behavior of water. Understanding water chemistry is essential for ensuring clean and safe drinking water, and for managing water resources in our environment.Water is a polar molecule, meaning it has a partial negative charge on one side and a partial positive charge on the other. This property allows water to dissolve many substances, making it an excellent solvent for many chemical reactions. Water also has a high surface tension, which allows it to create an interface between air and water, forming water droplets and aiding in capillary action.The pH level of water is also an important aspect of water chemistry. The pH scale ranges from 0 to 14, with 7 being neutral. Water typically has a pH level of around 7, which is considered neutral. Water that has a pH level below 7 is considered acidic, while water with a pH level above 7is considered basic or alkaline.The chemical composition of water is also important to consider. Pure water consists of two hydrogen atoms and one oxygen atom (H2O). However, most natural water sources contain a variety of dissolved minerals and ions, such as calcium, magnesium, and sodium. These minerals can have a significant impact on the properties of water, affecting its taste, hardness, and ability to conduct electricity.Water chemistry is important for a variety of applications, including water treatment, environmentaltesting, and industrial processes. By understanding the chemical properties of water and how it interacts with other substances, we can better manage and protect this precious resource for future generations.。
第三章-环境水化学finalized
陆地水主要由大气降水补给。我国西北地区的一些河 流，受冰川融水补给重用明显，河流流量变化与气温 变化有密切的关系。河流水、湖泊水、地下水之间， 具有水源补给的关系。当河流水位高于湖面或潜水面 时，河流水补给湖泊水或地下潜水；当河流水位低于 湖面或潜水面，湖泊水或潜水补给河流。湖泊对河流 径流还起调蓄作用，在洪水期蓄积部分洪水，可以延 缓、削减河川洪峰。例如我国长江中下游地区的许多 湖泊，对长江及其支流的洪水起着天然的调节作用。 自然界的水周而复始连续运动的过程叫水循环。它使 陆地水不断得到补充、更新，使水资源得以再生。
水中主要离子组成图
水中的金属离子 (2) 水中的金属离子： 水溶液中金属离子的表示式常写成Ｍn+， 预示着是简单的水合金属阳离子 M（Ｈ２Ｏ）xn+.它可通过化学反应达到最 稳定的状态，酸-碱、沉淀、配合及氧化还原等反应是它们在水中达到最稳定状态 的过程。 水中可溶性金属离子可以多种形态存在。
水中的气体
重水在自然界含量非常少，而且它是和反应堆的 中子慢化剂，在大功率的原子反应堆中需要它， 同时又是生产氢弹的原料，但是从普通水中提取 重水要耗费非常多的能量。估计13万kWh/kg重水 。 超重水中的氚T是一种放射性同位素，能够放射 出β射线。一般超重水用于医学、生物、物理、 化学上的示踪剂。
地表水主要包括江河水、湖沼水和以固体形态存在 的冰川等。降水和地表水下渗到地下的土层和岩石 空隙中，成为地下水。陆地水体从静态储水量看， 以冰川和地下水储水量最大。 地下水按其埋藏条件主要可分为（表面滞水）潜水 和承压水。潜水是埋藏在地下第一个隔水层（指透 水性能差的岩层和土层，一般由致密的岩石或粘土 组成，空隙小，地下水不易透过）之上的地下水， 有一个自由水面。承压水是埋藏在两个隔水层之间 承受一定压力的地下水，没自由水面。
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Hypoxia in the Gulf of Mexico
From NCAT (Nat’l Center for Appropriate Technology) /nutrients/hypoxia/hypoxia.html
Global distribution of oxygen-depleted coastal zones. Annual = yearly events (summer or autumnal stratification) Episodic = occurring at irregular intervals > one year Periodic = occurring at regular intervals < one year Persistent = all-year-round hypoxia
Sources: Boesch 2002, Caddy 2000, Diaz and others (in press), Green and Short 2003, Rabalais 2002
Source: Patrick Heffer, Short Term Prospects for World Agriculture and Fertilizer Demand 2002/03 - 2003/04 (Paris: International Fertilizer Industry Association (IFA), December 2003); IFA Secretariat and IFA Fertilizer Demand Working Group, Fertilizer Consumption Report (Brussels: December 2001); historical data from Worldwatch Institute, Signposts 2002, CD-ROM, compiled from IFA and the U.N. Food and Agriculture Organization, Fertilizer Yearbook (Rome: various years).
Plants uptake nitrates (Spinach a good source).
Redfield Ratio: 106:16:1
Nitrates
Artificial sources:
• Livestock manure/urine • Failing septic systems • Synthetic fertilizers
Leads to changes in ecosystem as organisms needing lots of DO are replaced by organisms needing little.
Hood Canal, Wash. DO
Hood Canal
Sill
Saltwater from entry point. Freshwater from stream and river runoff.
Modified from .au/fortheteacher/manual/sect4f.htm
Factors that affect pH
• Algal blooms • Bacterial activity • Water turbulence • Chemicals flowing into the water body • Sewage overflows • Pollution
Hardness
Reflects dissolved carbonate minerals. Mostly of concern for drinking water standards. Metals precipitate out of solution. Create scale/hard water deposits High alkalinity Hard water
Temperature
Affects: Water density Gas solubility Chemical reaction rates Organism growth rates Conductivity pH Dissolved Oxygen
Temperature – naturally varies because of…
Dissolved Oxygen (DO)
DO is the measurement of oxygen dissolved in water and available for fish and other aquatic life. Indicates health of an aquatic system. Can range from 0-18 ppm. Most natural water systems require 56 ppm to support a diverse population.
Gulf of Mexico
Mississippi River drainage basin – 41% of US landmass.
Hypoxia in the Gulf of Mexico
c waters
Image from Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC, January 2003
Phosphates
Artificial sources: • Sewage • Laundry, cleaning fluids • Synthetic fertilizers
Can also lead to eutrophication of natural water systems (overproduction of vegetation)
Varies with time of day, weather, temperature.
Dissolved Oxygen (DO)
Increase in organic waste
Increase in algae/plant vegetation
Decrease in DO available to organisms
In natural water systems, determined largely by geology and soils.
pH of natural waters
Sea water due to humic acid
Limestone, marble, CO3 rich
Pure rain, snow
Can lead to:
eutrophication of natural water systems (overproduction of vegetation) Blue baby syndromne The U.S. EPA has set a maximum contaminant level for NO3- in drinking water of 10 parts per million (ppm)
Blue green algae
1990 and 1999 comparison of Nitrates in Great Lakes
From US EPA /glnpo/monitoring/limnology/SprNOx.html
Hypoxia in the Gulf of Mexico
Alkalinity refers to the capability of water to neutralize acid. Buffering capacity – resistance to pH changes. Common natural buffer: CO3 (carbonates – like limestone). Protects aquatic life. Commonly linked to water hardness. Limestone outcrop In natural systems: 50 – 150 mg/L as CaCO3.
From USGS /owq/news.html
and
Nitrate (NO3-) naturally-occurring form of nitrogen found in soil. Forms by microbial decomposition of fertilizers, plants, manures or other organic residues Phosphate (PO4-3) naturally occurs in rocks and minerals. Plants uptake weathered-out elements and compounds. Animals ingest plants. Water soluble.
… Changes in seasonal/diurnal air temperature … Thermal stratification in lakes … Size and temperature of inflows … Residence time (lakes)
Temperature – artificially varies because of…
How pH affects aquatic life
Decreasing pH
(e.g.: via acid rain)
▼ Liberation of Al, metals ▼ Toxic conditions ▼ Chronic stress ▼ Smaller, weaker fish
Alkalinity