| Chinese | English |
| 一氧化二氮 | nitrogen monoxide A colourless gas, soluble in water, ethanol and ether. It is formed in many reactions involving the reduction of nitric acid, but more convenient reactions for the preparation of reasonably pure NO are reactions of sodium nitrite, sulphuric acid, etc. (一种无色气体，易溶于水、乙醇和乙醚。它形成于一些硝酸还原反应中，但更方便的制备纯氧化氮反应的是亚硝酸钠、硫酸等反应。) |
| 二元经济 | dual economy An economy based upon two separate/distinct economic systems which co-exist in the same geographical space. Dualism is characteristic of many developing countries in which some parts of a country resemble advanced economies while other parts resemble traditional economies, i.e. there are circuits of production and exchange (存于同一地理空间，但基于两种相互分离的或完全不同的经济系统下的一种经济。 双重或二元经济论是许多发展中国家的经济特征，国家的一部分地区类似先进经济，而其他地区却是类似传统经济，即具有生产和交易的轮替性。) |
| 二冲程发动机 | two-stroke engine An internal combustion engine whose cycle is completed in two strokes of the piston (一种内燃发动机，其循环是通过两个活塞冲程完成。) |
| 二恶英 | polychlordibenzo-p-dioxin PCDD are formed (along with variants including furans) when compounds containing chlorine are burnt at low temperature in improperly operated/designed domestic refuse and industrial waste incinerators where PCDDs can be found in both the flue gases and the fly ash (形成PCDD(包括呋喃等变异体)，当包含氯的化合物被燃烧后，PCDDs可以在废气和飞烟中找到。由于废料和工业废料焚烧炉的设计和操作不当会产生该物质。) |
| 二手商品 | second-hand goods Goods or products that have been used previously (以前被使用过的商品或产品。) |
| 二次处理 | secondary treatment Stage of the process of waste water treatment: following primary treatment by sedimentation, the second step in most wastewater systems in which biological organisms decompose most of the organic matter into a innocuous, stable form (废水处理过程：在通过沉淀处理的第一次处理之后，大多数废水处理系统的第二步是微生物把有机物分解成无害的、稳定的状态。) |
| 二次燃烧 | afterburning An afterburner is a gadget fitted to the exhaust flues of furnaces and also to the exhaust systems of motor vehicles. They remove polluting gases and particles, which are the result of incompletely combusted fuel, by incineration and break down other chemical molecules associated with combustion into inert chemicals (后燃器是用于锅炉烟道或机动车排气系统的配件，可以通过焚化和分解将化学分子氧化为惰性化学物质，从而清除燃料不充分燃烧后产生的有毒气体和微粒。) |
| 二氧化氮 | nitrogen dioxide A reddish-brown gas; it exists in varying degrees of concentration in equilibrium with other nitrogen oxides; used to produce nitric acid, NO2 (一种红棕色的气体；它存在不同的浓度以平衡其他氮氧化物；过去常常用来生产硝酸。) |
| 二氧化硫 | sulphur dioxide Emissions of the gas given off during the burning of fossil fuels in power stations and other boilers. Sulphur dioxide is created because sulphur is an impurity in most coal and oils. When the fuel is burned the hot sulphur reacts with oxygen in the atmosphere to form sulphur dioxide, SO2 (电站锅炉和其它化石燃料的燃烧期间排放的气体。二氧化硫的形成是因为在大多数的煤和油中存在硫杂质。当燃料燃烧大气中的氧气，通过热硫反应生成二氧化硫。) |
| 二氧化硫胁迫 | sulfur dioxide stress |
| 二氧化硫胁迫 | SO₂stress |
| 二氧化碳 | carbon dioxide A colourless gas with a faint tingling smell and taste. Atmospheric carbon dioxide is the source of carbon for plants. As carbon dioxide is heavier than air and does not support combustion, it is used in fire extinguishers. It is a normal constituent of the atmosphere, relatively innocuous in itself but playing an important role in the greenhouse effect. It is produced during the combustion of fossil fuels when the carbon content of the fuels reacts with the oxygen during combustion. It is also produced when living organisms respire. It is essential for plant nutrition and in the ocean phytoplankton is capable of absorbing and releasing large quantities of the gas, CO2 (一种无色的气体，有淡淡的刺激性气味和味道。大气中的二氧化碳是植物的碳源。由于二氧化碳比空气重并且不支持燃烧，二氧化碳被用作灭火剂。它是大气的基本组成部分，相对无害，但是在温室效应中扮演着一个重要的角色。它是碳和氧气在燃烧过程中发生反应而产生的，也在生物体呼吸时产生。它是必要的植物营养，而且海洋浮游植物也能吸收和释放大量的二氧化碳。) |
| 二氧化碳同化的三碳途径 | C3 pathway of CO2 assimilation |
| 二氧化碳固定 | carbon capture |
| 二氧化碳固定 | carbon dioxide fixation |
| 二氧化碳固定 | carbon fixation |
| 二氧化碳税 | carbon dioxide tax Compulsory charges levied on fuels to reduce the output of carbon dioxide (CO2), which is a colourless and odourless gas substance that is incombustible (强制征收的燃料费，用来降低二氧化碳(CO2)的排放，该气体是一种无色无味不可燃烧的气体。) |
| 二氧化钛 | titanium dioxide A white, water-insoluble powder that melts at 1560°C, and which is produced commercially from the titanium dioxide minerals ilmenite and rutile; used in paints and cosmetics (一种白色，不溶于水的粉末，在1560°C时融化，存在于二氧化钛矿物，钛铁矿和金红石，用于油漆和化妆品工业。) |
| 二碳光合作用 | C2 photosynthesis |
| 二级变水 类型 | secondarily poikilohydric form |
| 外围空气的二氧化硫浓度 | sulphur concentration Sulphur content in a solution (硫含量的解决方案。) |
| 多氯二苯并呋喃 | polychlorinated dibenzofuran A family containing 135 individual, colorless compounds known as congeners with varying harmful health and environmental effects. They are produced as unwanted compounds during the manufacture of several chemicals and consumer products such as wood treatment chemicals, some metals, and paper products; also produced from the burning of municipal and industrial waste in incinerators, from exhaust of leaded gasoline, heat, or production of electricity. They are hazardous to the respiratory system, gastrointestinal system, liver, musculoskeletal system, skin and nervous system; and are toxic by inhalation, ingestion, and contact. Symptoms of exposure include frequent coughing, severe respiratory infections, chronic bronchitis, abdominal pain, muscle pain, acne rashes, skin color changes, unexpected weight loss, nonmalignant or malignant liver disease (一个包含135种个体的化合物族，其中的无色化合物个体包含的有效杂质有害人体健康和对环境产生不利影响。这类化合物一般是作为不希望得到的化合物在生产过程中产生的，比如木处理化学品，某些金属、纸制品生产的附属物，也可以从燃烧工业废料中产生。它们对呼吸系统、消化系统、肝脏、皮肤和骨骼系统、神经系统都有害。吸入、摄入和接触后会产生中毒症状，包括严重的呼吸道感染、咳嗽、慢性支气管炎、腹部疼痛、肌肉疼痛、痤疮皮肤皮疹、皮肤颜色变化、体重下降和一些肝脏恶性疾病。) |
| 朗伯一毕尔二氏消光法则 | Lambert-Beer's extinction law |
| 第二族元素 | element of group Any of the divalent electropositive metals beryllium, magnesium, calcium, strontium, barium, and radium, belonging to group 2A of the periodic table; alkaline earth metals (任何带正二价电荷的金属，如：铍、镁、钙、锶、钡、镭属于周期表的第2A族。) |
