Seawater

海水

Water has great abundance on the Earth, and of that abundance about 97% is sea water. Sea water contains about 3.5% by weight of salt (sodium chloride). The salinity does vary, and the combination of salinity and temperature has a major influence on ocean currents and behavior. Salinity is a crucial property of the seas and is widely measured. Among the variouse ways to characterize the average salinity are 35 ppt (parts per thousand), 35 psu (practical salinity units). The typical range of salinity is about 33 to 37 ppt. About 70% of the Earth is covered with water. The salt in that water would build a 180 mile high, 1 mile thick wall around the equator according to the Windows to the Universe website.

地球上的水非常丰富，其中约97%是海水。海水含盐量约为3.5%（以重量计，即氯化钠）。含盐量会有所变化，含盐量与温度的组合对洋流和行为有重大影响。含盐量是海洋的一个关键属性，并被广泛测量。表征平均含盐量的几种方法包括35 ppt（千分之三十五）和35 psu（实用盐度单位）。含盐量的典型范围约为33到37 ppt。地球上的水覆盖面积约为70%。根据Windows to the Universe网站的数据，这些水中的盐如果堆成墙，将形成一个围绕赤道高180英里、厚1英里的墙。

Dissolved salts in sea water (atoms) 海水中的溶解盐（原子）
Chlorine 氯	55.3%
Sodium 钠	30.8%
Magnesium 镁	3.7%
Sulfur 硫	2.6%
Calcium 钙	1.2%
Potassium 钾	1.1%

There are other salts dissolved in sea water, with ordinary sodium chloride constituting about 90% of the dissolved salt. The table at left is given by the Windows on the Universe website. It is not clear how you reach charge neutrality with these numbers. Another item of information from this site was that deep ocean water was at about 3°C and salinity 34-35 ppt. Seawater of average salinity 35 ppt freezes at -1.94°C (28.5°F). The salinity of the water is measured with a CTD instrument (Conductivity, Temperature, Depth). The conductivity is used to calculate the salinity in conjunction with the temperature and depth (pressure) measurements.

海水中还溶解着其他盐类，普通氯化钠约占溶解盐的90%。左边的表格来自Windows on the Universe网站。这些数值如何达到电中性尚不清楚。该网站还提供了另一项信息：深海海水温度约为3°C，盐度为34-35‰。盐度为35‰的海水冻结温度为-1.94°C（28.5°F）。水的盐度是通过CTD仪器（电导率、温度、深度）测量的。电导率与温度和深度（压力）测量相结合，用于计算盐度。

Seawater has an average density of 1.027 gm/cm³, but this varies with temperature and salinity over a range of about 1.020 to 1.029. The density is typically indicated by a density index σ which is the departure of the density from 1.000 multiplied by a thousand.

海水的平均密度为1.027 gm/cm 3 ，但其会因温度和盐度而变化，范围大约在1.020到1.029之间。密度通常用密度索引σ表示，它等于密度偏离1.000的值乘以一千。