There are many sources of vanadium in environment. Human activities, especially combustion of fossil fuel, make the quantity of vanadium in environment increase intensively.
环境中的钒有多种不同来源，人类活动，尤其是大量化石燃料的燃烧，使环境中钒含量急剧增加。
The treated fuel has reduced levels of vanadium, nickel and other metals.
处理过的燃料中钒、镍和其它金属的含量降低。
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