摘要
Dianchi Lake is a highly eutrophic lake in southwestern China where phosphorus (P) is the limiting element for eutrophication and where lake sediments play an important role in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 to investigate the P loading of the lake sediments, while fresh surface sediments were studied in the laboratory to clarify its role for phosphorus. The results showed that concentrations of total phosphorus (TP) in sediments were very high, with a maximum value of 6.66 g kg-1, and decreased with sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher in acidic than in alkaline conditions. The release experiments showed that P release increased as pH rose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higher under anaerobic conditions, especially with low P content in the lake water. At present, the sediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water. However, if the external P load was reduced and P content in lake water became low, the sediment would have a large potential for P release under anaerobic conditions.
Dianchi Lake is a highly eutrophic lake in southwestern China wherephosphorus (P) is the limiting element for eutrophication and where lake sediments play an importantrole in the P cycle. One hundred and eighteen sites were sampled throughout Dianchi Lake in 2002 toinvestigate the P loading of the lake sediments, while fresh surface sediments were studied in thelaboratory to clarify its role for phosphorus. The results showed that concentrations of totalphosphorus (TP) in sediments were very high, with a maximum value of 6.66 g kg^(-1), and decreasedwith sediment depth. P adsorption on surface sediments was rapid with adsorption amounts higher inacidic than in alkaline conditions. The release experiments showed that P release increased aspHrose from 7.0 to 10.5. Additionally, compared with aerobic conditions, P release was much higherunder anaerobic conditions, especially with low P content in the lake water. At present, thesediments in Dianchi Lake still function as a sink for phosphorus at high P levels in lake water.However, if the external P load was reduced and P content in lake water became low, the sedimentwould have a large potential for P release under anaerobic conditions.
基金
Project supported by the Innovation Fund of the Institute of Soil Sciences, Chinese Academy of Sciences (Nos. 5022505 and 005301).
