求翻译：分析，统计，评价得出兰州市地表水污染一生物、有机类为主，无机、金属类次之。水质情况均达到国家三级标准，污染程度在2003-2007年减轻是什么意思？

Analysis, statistics, evaluation come to Lanzhou City surface water pollution biology, organic-based, inorganic, followed by metals. Water quality have reached three national standards, pollution levels in 2003-2007 to reduce

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The analysis, the statistics, the appraisal obtains a Lanzhou city surface water pollution living thing, the organic kind primarily, inorganic, Jin Shulei is next.The water quality situation achieved the national three levels of standards, the pollution degree reduces in 2003-2007 year

Analysis, statistics, and evaluation of surface water pollution in Lanzhou city a biological, organic, inorganic, metal classes following behind. Reach national levels of water quality standards, pollution levels in 2003-2007 reduction

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