| Title | Long-term change in the trophic status and mixing regime of a deep volcanic lake (Lake Bolsena, Central Italy) |
| Abstract | Lake Bolsena, the fourth Italian lake for volume (9.2âEUR?×âEUR?109âEUR?m3), must be considered as highly sensitive to eutrophication for its extremely long water renewal time. In this paper, temperature and chemical characteristics of the lake measured in the period 2003-2017 are used to discuss the mixing pattern and the variation in the oxygen and algal nutrient concentrations, as indicators of the trophic level. In the analysed period the lake showed oligomictic characteristics, reaching the full overturn, with homogenization of the chemical profile over the whole water column, only in 4 out of the 15 considered years. A regular decrease of oxygen and increase of phosphorus concentrations in the deepest layers has been observed in the non-circulating multi-year periods. The mean total phosphorus concentration showed a regular increase, reaching values close to 16âEUR?μgâEUR?P Lâ^'1 in early spring 2017, mostly because of the urban discharge from the watershed, not adequately collected from an existing sewage pipe. Chemical and mixing patterns are discussed in relation with a previous study, carried out in 1966-1971, confirming the recent increase of phosphorus concentrations and the lower frequency of full circulation. The progressive deterioration of lake water quality indicates the need of prompt actions to reduce the external nutrient load and of further studies on the physical and biological characteristics of the lake, still strongly missing. |
| Source | Limnologica (Jena) 72 (-), pp. 1–9 |
| Keywords | Eutrophication Lake mixing Climate change Volcanic lakes |
| Journal | Limnologica (Jena) |
| Editor | Elsevier, München, Germania |
| Year | 2018 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.limno.2018.07.002 |
| Authors | Mosello R.; Bruni P.; Rogora M.; Tartari G.; Dresti C. |
| Text | 399128 2018 10.1016/j.limno.2018.07.002 Scopus 2 s2.0 85051376216 ISI Web of Science WOS 000447777500001 Eutrophication Lake mixing Climate change Volcanic lakes Long term change in the trophic status and mixing regime of a deep volcanic lake Lake Bolsena, Central Italy Mosello R.; Bruni P.; Rogora M.; Tartari G.; Dresti C. National Research Council, Institute of Ecosystem Study, Largo V. Tonolli 50, Verbania Pallanza, VB, 28922, , Italy; Associazione Lago di Bolsena, Via 25 aprile 10, Marta, VT, 01010, , Italy Lake Bolsena, the fourth Italian lake for volume 9.2aEUR ×aEUR 109aEUR m3 , must be considered as highly sensitive to eutrophication for its extremely long water renewal time. In this paper, temperature and chemical characteristics of the lake measured in the period 2003 2017 are used to discuss the mixing pattern and the variation in the oxygen and algal nutrient concentrations, as indicators of the trophic level. In the analysed period the lake showed oligomictic characteristics, reaching the full overturn, with homogenization of the chemical profile over the whole water column, only in 4 out of the 15 considered years. A regular decrease of oxygen and increase of phosphorus concentrations in the deepest layers has been observed in the non circulating multi year periods. The mean total phosphorus concentration showed a regular increase, reaching values close to 16aEUR μgaEUR P La 1 in early spring 2017, mostly because of the urban discharge from the watershed, not adequately collected from an existing sewage pipe. Chemical and mixing patterns are discussed in relation with a previous study, carried out in 1966 1971, confirming the recent increase of phosphorus concentrations and the lower frequency of full circulation. The progressive deterioration of lake water quality indicates the need of prompt actions to reduce the external nutrient load and of further studies on the physical and biological characteristics of the lake, still strongly missing. 72 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 85051376216 partnerID=q2rCbXpz Articolo 2018_Limnologica_72_1_9.pdf Articolo in rivista Elsevier 0075 9511 Limnologica Jena Limnologica Jena Limnologica Jena Limnologica. Jena Limnologica Munchen. Print Jena claudia.dresti DRESTI CLAUDIA rosario.mosello MOSELLO ROSARIO michela.rogora ROGORA MICHELA gabriele.tartari TARTARI GABRIELE |
