摘要
关于河流磷(P)浓度以及向瑞典第三大湖梅拉伦湖的磷输送量,现已在12条大支流中进行了为时35年的监测。在15个月时间内,对颗粒磷、悬浮物以及溶解活性磷进行了补充评价。按照水流加权平均值,颗粒磷占64%,溶解非活性磷占23%,溶解活性磷占13%,而且季节性变化很大。对河流中的'背景'或'基准'磷输送量采用不同方法进行了估算,而人为对磷输送量的贡献呈现出随着时间推移而减少的趋势。对于排了水的耕地和森林覆盖地来说,藻类对颗粒磷的潜在利用率平均约为45%,而污水排放颗粒磷和藻类磷的利用率则较高。支流中的计算生物可利用总磷显示出与粗过滤水上测得的活性磷相等,同时有迹象表明在人为磷贡献率高的时期生物可利用磷的比例要比人为磷贡献率低的时期高。
Riverine phosphorus (P) concentration and P-transport to Lake Malaren, the third largest lake in Sweden, has been monitored for 35 years in 12 major tributaries. During a period of 15 months, complementary assessments of particulate P, suspended matter and dissolved reactive P were made. Particulate P comprised 64%, dissolved unreactive P 23% and dissolved reactive P 13% as flow-weighted means, with high seasonal variability. “Background” or “reference” P-transports in the streams were estimated by different methods and the anthropogenic contribution to P-transport was shown to be reduced over time. Potential algal availability of particulate P showed a mean availability of c. 45% for water draining arable and forested land, while the availability was higher for sewage discharge particulate P and algal P. Calculated total bioavailable P in tributaries was shown to equal reactive P measured on coarsely filtered water and it was indicated that the proportion of bioavailable P was higher during the period with high anthropogenic P-contribution than with a lower contribution.
