Nutrient responses to the liming of lake G�rdsj�n

Abstract

The acidified lakes Lake Gardsjon and Lake Stora Hastevatten the reference lake have been monitored since 1979 and 1980 respectively. The lakes are situated in SW Sweden; in an area severly affected by acid deposition. Lake Gardsjon was limed in spring 1982. This paper analyses changes in nutrient concentrations upon liming of Lake Gardsjon. The liming of Lake Gardsjon was followed by a slight increase in ammonium, nitrate, and dissolved organic nitrogen concentrations. A drastic decrease occurred in particulate nitrogen and particulate carbon, whereas dissolved organic carbon increased. Total phosphorus and particulate phosphorus concentrations were similar to pre-limed conditions. The long-term decrease in phosphorus concentration, exhibited by the reference lake, was not identified in Lake Gardsjon after liming, but total phosphorus concentration was still less than half compared to Lake Gardsjon in the early 1970's. Additional measures such as phosphorus fertilization, should in certain cases be considered in addition to liming if the goal is to restore lakes to their pre-acidic conditions.