| Title | Present trophic level of Lake Alserio (Northern Italy) and prospect for its recovery. |
| Abstract | Lake Alserio is located in the subalpine area of northern Italy, in the Brianza region near Lake Como. In November 1999 an EU funded project was started with the aim of devising and implementing interventions leading to the recovery of the lake and the surrounding area, which is characterised by a high degree of biodiversity as regards species and natural habitats. Since the seventies, Lake Alserio has been affected by eutrophication, which has resulted in high phosphorus (P) concentrations (annual average in 1999: 80-100 mug P l-1). The EU project envisaged liming the lake with Ca(OH)2 to reduce P concentrations in the water. This paper presents and discusses the results of chemical analyses performed on the lake and its tributaries in the first year of the study (November 1999-November 2000). The efficiency of liming with Ca(OH)2 to reduce P concentrations in laboratory and enclosure experiments is also discussed. The present condition of Lake Alserio is between eutrophic and hypereutrophic. Anoxic conditions characterise the hypolimnic waters for a prolonged period (May-October) during summer stratification, with a consequent high P release from the sediments (summer P concentrations in the deep water are close to 1 mg P l-1). Inflowing waters are characterised by high contents of ammonium and phosphorus, showing the importance of domestic sewage in the lake catchment; external load is still too high to permit the water to reach mesotrophic condition, the ultimate goal of recovery. Results of the liming experiments suggest that the treatment, if applied to Lake Alserio, could accelerate its recovery, although the specific procedures to be employed are still to be defined. However, before these or any other remedial operations can be undertaken, the external P load must be reduced by completing the diversion of sewage from the lake. |
| Source | Journal of limnology (Testo stamp.) 61 (1), pp. 27–40 |
| Keywords | eutrophicationphosphorusmeromictic lakes |
| Journal | Journal of limnology (Testo stamp.) |
| Editor | Istituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia |
| Year | 2002 |
| Type | Articolo in rivista |
| Authors | Rogora, Michela; Garibaldi, Letizia; Morabito, Giuseppe; Arisci, Silvia; Mosello, Rosario |
| Text | 407795 2002 ISI Web of Science WOS BCI200300337736 eutrophication phosphorus meromictic lakes Present trophic level of Lake Alserio Northern Italy and prospect for its recovery. Rogora, Michela; Garibaldi, Letizia; Morabito, Giuseppe; Arisci, Silvia; Mosello, Rosario C.N.R. Istituto per lo Studio degli Ecosistemi, L.go Tonolli 50, 28922, Verbania Pallanza, Italy Lake Alserio is located in the subalpine area of northern Italy, in the Brianza region near Lake Como. In November 1999 an EU funded project was started with the aim of devising and implementing interventions leading to the recovery of the lake and the surrounding area, which is characterised by a high degree of biodiversity as regards species and natural habitats. Since the seventies, Lake Alserio has been affected by eutrophication, which has resulted in high phosphorus P concentrations annual average in 1999 80 100 mug P l 1 . The EU project envisaged liming the lake with Ca OH 2 to reduce P concentrations in the water. This paper presents and discusses the results of chemical analyses performed on the lake and its tributaries in the first year of the study November 1999 November 2000 . The efficiency of liming with Ca OH 2 to reduce P concentrations in laboratory and enclosure experiments is also discussed. The present condition of Lake Alserio is between eutrophic and hypereutrophic. Anoxic conditions characterise the hypolimnic waters for a prolonged period May October during summer stratification, with a consequent high P release from the sediments summer P concentrations in the deep water are close to 1 mg P l 1 . Inflowing waters are characterised by high contents of ammonium and phosphorus, showing the importance of domestic sewage in the lake catchment; external load is still too high to permit the water to reach mesotrophic condition, the ultimate goal of recovery. Results of the liming experiments suggest that the treatment, if applied to Lake Alserio, could accelerate its recovery, although the specific procedures to be employed are still to be defined. However, before these or any other remedial operations can be undertaken, the external P load must be reduced by completing the diversion of sewage from the lake. 61 Published version Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. rosario.mosello MOSELLO ROSARIO michela.rogora ROGORA MICHELA |
