摘要
This paper presents the process and technical method to develop lake nutrient criteria,analyses mainly the approaches of nutrient variables selection and lake reference condition establishment.Nutrient variables involve necessarily the indicators of overenrichment and lake geographic differences,and possess the characteristics of relatively stability,ecoregion and eutrophication prediction.Several methods of reference condition establishment have been reviewed as statistical distributions of direct observation of reference lakes,model prediction and extrapolation,and paleolimnological reconstruction.Through analyzing historical and existing water quality data and biological information,statistical approach could ensure the established criteria is applicable for most lakes.However,the reference conditions are not specifically established by this approach when the lakes lack observation or significantly impacted by human activity.Model prediction and extrapolation can be used for lakes suffered anthropogenic disturbances,and needs to be recalibrated and tested with large data sets.Paleolimnological reconstruction approach tracks the natural background concentrations of lake nutrients and quantitatively restores past conditions by using sediment cores,and requires complex analyses and expert judgments.It is difficult to reconstruct the past nutrient condition of shallow lakes in which sediments ate easily disturbed.Most of lakes have been impacted seriously by human activity in China,lack historical data record,and have significant geographic differences.Therefore,it is necessary to optimize and improve the methods of lake nutrient criteria development and establish an integrated methodology system of nutrient criteria development in China,direct us develop numeric criteria for nutrients to protect the designated uses from cultural eutrophication.