{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T06:30:21Z","timestamp":1772519421214,"version":"3.50.1"},"reference-count":54,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2020,12,1]],"date-time":"2020-12-01T00:00:00Z","timestamp":1606780800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005781","name":"Koneen S\u00e4\u00e4ti\u00f6","doi-asserted-by":"publisher","award":["085244"],"award-info":[{"award-number":["085244"]}],"id":[{"id":"10.13039\/501100005781","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The trophic state of Lake Ladoga was studied during the period 1997\u20132019, using the Copernicus Marine Environmental Monitoring Service (CMEMS) GlobColour-merged chlorophyll-a OC5 algorithm (GlobColour CHL-OC5) satellite observations. Lake Ladoga, in general, is mesotrophic but certain parts of the lake have been eutrophic since the 1960s due to the discharge of wastewater from industrial, urban, and agricultural sources. Since then, many ecological assessments of the Lake\u2019s state have been made. These studies have indicated that various changes are taking place in the lake and continuous monitoring of the lake is essential to update the current knowledge of its state. The aim of this study was to assess the long-term trend in chl-a in Lake Ladoga. The results showed a gradual reduction in chl-a concentration, indicating a moderate improvement. Chl-a concentrations (minimum-maximum values) varied spatially. The shallow southern shores did not show any improvement while the situation in the north is much better. The shore areas around the functioning paper mill at Pitk\u00e4ranta and city of Sortavala still show high chl-a values. These findings provide a general reference on the current trophic state of Lake Ladoga that could contribute to improve policy and management strategies. It is assumed that the present warming trend of surface water may result in phytoplankton growth increase, thus partly offsetting a decrease in nutrient load. Precipitation is thought to be increasing, but the influence on water quality is less clear. Future studies could assess the current chemical composition to determine the state of water quality of Lake Ladoga.<\/jats:p>","DOI":"10.3390\/s20236881","type":"journal-article","created":{"date-parts":[[2020,12,1]],"date-time":"2020-12-01T20:06:09Z","timestamp":1606853169000},"page":"6881","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Assessing the Trend of the Trophic State of Lake Ladoga Based on Multi-Year (1997\u20132019) CMEMS GlobColour-Merged CHL-OC5 Satellite Observations"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3322-6631","authenticated-orcid":false,"given":"Augustine-Moses Gaavwase","family":"Gbagir","sequence":"first","affiliation":[{"name":"School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, Borealis Building A 3rd Floor, 80101 Joensuu, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5833-7309","authenticated-orcid":false,"given":"Alfred","family":"Colpaert","sequence":"additional","affiliation":[{"name":"Department of Geographical and Historical Studies, University of Eastern Finland, Yliopistokatu 7, Metria-Building, P.O. Box 111, FI-80101 Joensuu, Finland"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/j.jglr.2013.05.002","article-title":"Multi-year satellite observations of Lake Ladoga\u2019s biogeochemical dynamics in relation to the lake\u2019s trophic status","volume":"39","author":"Pozdnyakov","year":"2013","journal-title":"J. Great Lakes Res."},{"key":"ref_2","unstructured":"Moiseenko, T.I., and Sharov, A.N. (2011). The retrospective analysis of aquatic ecosystem modification of Russian large lakes under antropogenic impacts. Ecotoxicology around the Globe, Nova Science Publishers, Inc."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Rukhovets, L., and Filatov, N. (2010). 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