The standard states that the citric acid-sodium nitrate treatment is the least hazardous for removal of free iron and other metallic contamination and light surface contamination.

该标准声明：柠檬酸-硝酸钠处理在去除游离铁合其他金属污染和轻的表面污染物时，危险性最低。

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Unlike conventional methods of dissolving CO2 gas or metallic magnesium directly into ultrapure water, the MEGCON does not cause any secondary contamination or bubbling.

不像传统方式将CO2气体或金属镁直接溶入纯水中而产生二次污染，MEGCON的优点是不会产生二次污染及气泡。

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Engineers believe that the engine probably shut itself off when it was first started because of metallic grit or other contamination between the two high-voltage grids at the rear of the advanced engine.

CNN: Deep Space probe's ion engine working smoothly, NASA says