hardness of water meaning in English

水的硬度
水硬度
硬度标度

The source of hardness of water is the existence of dissolved calcium , magnesium and other metallic ions , which is harmless to humans
水中存在溶解之钙镁等金属离子物质为硬度来源，对健康无影响。
One group ( the soft water group ) of fish were exposed to the cd2 + concentration of 0 . 00 mg / l 0 . 06 mg / l 0 . 30 mg / l1 . 50 mg / l , the other group ( the hard water group ) were exposed to the same cd2 + concentration but increase the hardness of water to 16 degree ( germany degree ) by add calcium chloride into the solution
实验中将草鱼置于镉浓度分别为0 . 06mg l 、 0 . 3mg l 、 1 . 5mg l的水溶液中，每个梯度又分成软水组和硬水组，同时设软水对照和硬水对照，共8个组。软水组为自来水，硬水组为通过向水中加入cacl _ 2 ，使其硬度为16度(德国度) 。