选择去除 meaning in Chinese

selective removal

The results show that when the concentration of hmi ( hg2 + ) in influent water is every low , the effect of hmi removal by wbaer from dk is much better than cations exchange resins . with cations ( ca2 + , mg2 + ) at high concentration in raw water , wbaer has better selectivity to hmi in water , however the selectivity of cations exchange resins is worse . the anions in raw water such as cl - which is able to react with hmi can make cations exchange resins lose the capability of hmi removal , but it has no effect on wbaer ( d301g )
结果表明：当进水中重金属离子（ hg2 + ）浓度较低时，弱碱性阴离子交换树脂对饮用水中hg2 +的去除效果要明显优于阳离子交换树脂；当原水中含有相对较高浓度的阳离子（ ca2 + 、 mg2 + ）时，弱碱性阴离子交换树脂对水中的重金属离子具有很高的选择去除性，而阳离子交换树脂的选择去除性却很差；天然原水中能与重金属离子（ hg2 + ）发生络合反应的阴离子（如： cl ），可以使阳离子交换树脂丧失了对水中微量重金属离子（ hg2 + ）的去除作用，而对弱碱性阴离子交换树脂（ d301g型）去除水中微量hg2 +的影响却很小。