title: Temporal and spatial changes in nutrients and chlorophyll-a in a shallow lake, Lake Chaohu, China: an 11-year investigation.
abstract: Temporal and spatial changes of total nitrogen (TN), total phosphorus (TP) and chlorophyll-a (Chl-a) in a shallow lake, Lake Chaohu, China, were investigated using monthly monitoring data from 2001 through 2011. The results showed that the annual mean concentration ranges of TN, TP, and Chl-a were 0.08-14.60 mg/L, 0.02-1.08 mg/L, and 0.10-465.90 microg/L, respectively. Our data showed that Lake Chaohu was highly eutrophic and that water quality showed no substantial improvement during 2001 through 2011. The mean concentrations of TP, TN and Chl-a in the western lake were significantly higher than in the eastern lake, which indicates a spatial distribution of the three water parameters. The annual mean ratio of TN:TP by weight ranged from 10 to 20, indicating that phosphorus was the limiting nutrient in this lake. A similar seasonality variation for TP and Chl-a was observed. Riverine TP and NH4+ loading from eight major tributaries were in the range of 1.56 x 10(4)-5.47 x 10(4) and 0.19 x 10(4)-0.51 x 10(4) tons/yr over 2002-2011, respectively, and exceeded the water environmental capability of the two nutrients in the lake by a factor of 3-6. Thus reduction of nutrient loading in the sub-watershed and tributaries would be essential for the restoration of Lake Chaohu.
authors.affiliation: River and Coastal Environment Research Center Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
authors.forename: Libiao
authors.initials: L
authors.lastname: Yang
authors.forename: Kun
authors.initials: K
authors.lastname: Lei
authors.forename: Wei
authors.initials: W
authors.lastname: Meng
authors.forename: Guo
authors.initials: G
authors.lastname: Fu
authors.forename: Weijin
authors.initials: W
authors.lastname: Yan
mesh_terms: D002681:China; D002734:Chlorophyll / Q000032:analysis*; D000077194:Chlorophyll A; D004784:Environmental Monitoring / Q000379:methods*; D060106:Lakes / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis
chemical_list: D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A