美国溶解氧基准标准及其对我国的启示

US Dissolved Oxygen Criterion,Standard and Its Revelation for China

近年来我国水质量整体改善,但全国采用统一的溶解氧标准易导致不同地区水体欠保护或过保护.美国拥有相对完善的溶解氧标准体系,在综述了美国溶解氧基准标准制定体系的基础上,初步分析了我国溶解氧标准现存的不足及美国溶解氧标准制定对我国的启示.美国国家环境保护局通过分析不同溶解氧暴露情况对水生生物的影响,针对淡水和海水2种栖息地环境,对冷水和温水物种及其不同生活史阶段分别制定溶解氧基准值.美国各州参照溶解氧基准,考虑社会经济、反降级政策等因素,在不同时间和地点分别制定了保护指定水体功能的溶解氧标准值.我国现行的溶解氧标准值,主要参考国外发达国家标准制定,缺少对我国溶解氧背景浓度和水生生物溶解氧敏感性的基础研究.为制定符合我国国情的溶解氧基准标准,需在综合考虑我国气候、地理条件等自然因素对溶解氧影响基础上,开展水生生物对溶解氧敏感性、栖息地环境对物种及溶解氧浓度影响的相关研究工作,并综合考虑反降级政策,防止水质进一步恶化.

Water quality in China has improved markedly in recent years,while the adoption of single national dissolved oxygen(DO)standard is vulnerable to result in under-protection or over-protection of water in various regions.The United States(US)has a relatively perfect water quality standard system.The literature was examined to systematically discuss the development system of DO criterion and standard in US and its revelation for China,and preliminary analyze the disadvantages of the national DO standard.According to the analysis of the impacts of different DO exposure conditions on aquatic organisms,the US Environmental Protection Agency(US EPA)has established the DO criteria for cold water and warm water species and their different life history stages in view of the two habitat environments(freshwater and seawater).Taking into account DO criteria,social economy,and antidegradation policy,the States and Tribes of US have established DO standards to protect the designated water function in various times and places.The current DO standard values in China mainly referred to those of developed counties,lacking of basic research on the background DO concentration of and the DO sensitivity of aquatic organisms.In order to establish DO criteria and standards conforming to China′s national conditions,it is necessary to synthetically consider the impacts of climate,geographical conditions,and other natural factors on DO,carry out relevant research on the sensitivity of aquatic organisms to DO,the impacts of habitat environment on species and DO concentration.Meanwhile,the anti-degradation policy should be taken into consideration to develop DO standards,and to prevent further deterioration of water quality.