Correlations between algae and water quality: factors driving eutrophication in Lake Taihu, China

Abstract

Rapid population increase and economic growth in eastern China has lead to the degradation of many water bodies in the region, such as Lake Taihu, the third largest freshwater lake in China. Using data from recent investigations, the correlations between algae (measured as chlorophyll-a) and water quality indices in Lake Taihu were described by multivariate statistical analyses, and the key driving factors for the lake eutrophication were identified by principal component analysis. Results revealed strong spatiotemporal variation in the correlations between algae and water quality indices, suggesting that the limiting factor for the dominant algae growth depends on seasonality and location and it is necessary to reduce both nitrogen and phosphorus inputs for a long-term eutrophication control in this hyper-eutrophic system. Water temperature was another important controlling factor for algal growth in the lake. Using principal component analysis, nutrient contaminations from anthropogenic and natural inputs were identified as the key driving factor for the water quality problems of the lake. Moreover, five principal components were extracted and characterized with high spatial and seasonal variations in Lake Taihu. The key driving factors were believed to influence spatial variations including heavily polluted areas located in the northern and northwestern parts of the lake, where many manufacturing factories were built and wastewater from domestic and industrial plants was discharged. Based on this analysis, attention should be paid to effective land management, industrial wastewater treatment, and macrophytic vegetation restoration to reduce the pollutant loads and improve water quality. Principal component analysis was found to be a useful and effective method to reduce the number of analytical parameters without notably impairing the quality of information in this study.

Exploring the Spatial-Seasonal Dynamics of Water Quality, Submerged Aquatic Plants and Their Influencing Factors in Different Areas of a Lake

“…In agreement with this, the average concentrations of TN, TP and COD Mn declined from 1.25 mg·L −1 , 0.057 mg·L −1 and 4.63 mg·L −1 in 2011 to 1.15 mg·L −1 , 0.052 mg·L −1 and 4.45 mg·L −1 , respectively, during the wet season in 2012. During the cold season, reduced water temperatures, water level and light intensity are unfavorable for the growth of aquatic plants [60], and the biomass decreased to the lowest level in Honghu Lake.…”

Potential Drivers of the Level and Distribution of Nitrogen in the Hyporheic Zone of Lake Taihu, China

“…The overall nitrogen distribution in bottom water was closely related to input of nitrogen from polluted rivers around Lake Taihu and the overall flow direction from northwest to southeast [8,27,29]. The north and west zones of the lake receive large nutrient loads from some main rivers (Figure 1), including a large amount of agricultural runoff and drainage during the irrigation period (summer and winter), and the south zone also receives effluents and agricultural runoff from Zhejiang Province through rivers [4,29,30].…”

“…The north and west zones of the lake receive large nutrient loads from some main rivers (Figure 1), including a large amount of agricultural runoff and drainage during the irrigation period (summer and winter), and the south zone also receives effluents and agricultural runoff from Zhejiang Province through rivers [4,29,30]. High percentages of TN consisting of DIN in the bottom water also responded well to the nitrogen source distribution surrounding Lake Taihu.…”

Evaluating anthropogenic N inputs to diverse lake basins: A case study of three Chinese lakes

“…Generally, nutrient limitation for eutrophication of lakes is a case-specific question, depending on various factors such as temperature (Moss et al 2013), N deposition (Elser et al 2009), lake age (Moss et al 2013), and nutrient loading (Paerl et al 2011). For the three lake basins in this study, the high concentration of N in water is considered to be one of the main stressors for eutrophication in Lake Taihu, Lake Chaohu, and Lake Dianchi since phytoplankton is dominated by non-N-fixing cyanobacteria such as Microcystis (Liu 1999;Paerl et al 2011;Li et al 2014;Ma et al 2014). Recent studies on the relationship between nutrient concentrations and eutrophication show that N rather than P is the limiting nutrient in eutrophication of Lake Dianchi Fig.…”