Historic River Quality Objectives

This record is for Approval for Access product AfA164. The River Quality Objectives (RQO) classification was used for planning water quality improvements until 2006 when the scheme ended. RQOs were assigned to all significantly sized rivers (based on river flow). RQOs were based on the River Ecosystem (RE) Classification Scheme which was introduced in 1994 to replace the National Water Council's methodology. The RE system consists of five classes (1-5) based on the same determinands used in the General Quality Assessment (GQA) chemistry assessment of Biochemical Oxygen Demand (BOD), ammonia and dissolved oxygen but also includes the additional determinands of (free (or un-ionised) ammonia, pH, hardness, dissolved copper and total zinc) that reflect the requirements of a river ecosystem. Chemical samples were taken 12 times a year. Any river quality failures, their reasons and actions to be taken, were stored in separate tables. The national RQO classification scheme ceased at the end of 2006, it is now a fixed table which will not be updated. RQO compliance figures are available for 1997-2006. Attribution statement: © Environment Agency copyright and/or database right 2015. All rights reserved.本记录为准入产品AfA164的审批相关内容。 水质目标分级（River Quality Objectives, RQO）体系曾用于规划水质改善工作，直至2006年该体系正式废止。此前所有具有显著规模的河流（以径流量作为划分依据）均被纳入RQO分级范畴。RQO体系基于1994年推出的水生生态分类（River Ecosystem, RE）体系制定，用以取代原国家水理事会（National Water Council）的评估方法。 该RE体系共设5个等级（1至5级），其判定指标与通用质量评估（General Quality Assessment, GQA）中针对生化需氧量（Biochemical Oxygen Demand, BOD）、氨氮及溶解氧的化学评估所用指标一致，同时额外纳入了（游离/非离子化氨、pH值、硬度、溶解态铜及总锌）这些能够反映河流生态系统需求的判定指标。 每年会采集12次化学样本。河流水质不达标情况、成因及需采取的应对措施，均单独存储于独立的数据表中。 全国性RQO分级体系已于2006年底停止运行，目前仅作为固定数据表留存，不再进行更新。RQO合规性数据的覆盖时段为1997年至2006年。 版权声明：© 环境署（Environment Agency）2015年版权及/或数据库权利。保留所有权利。