Although point and nonpoint sources contribute roughly equal nutrient loads to lakes,their relative role in supporting algae growth has not been clarified. In this research, we have established a quantitative relation...Although point and nonpoint sources contribute roughly equal nutrient loads to lakes,their relative role in supporting algae growth has not been clarified. In this research, we have established a quantitative relationship between algae-available phosphorus(P) and P chemical fractions in sediments;the latter indicates the relative contribution of point versus nonpoint sources. Surface sediments from three large shallow lakes in eastern China, namely, the Chaohu, Taihu and Hongzehu Lakes, were sampled to assess their algaeavailable P and chemically extracted P fractions. The algae-available P primarily comes from iron/aluminium(hydr)oxide-bound P(Fe/Al-bound P), 45% of which is algae-available P. The ratio of Fe/Al-bound P to calcium compound-bound P(Ca-bound P) indicated the relative contribution of point to nonpoint sources, with the point sources contributing the majority of increased Fe/Al-bound P in sediments. Therefore, the reduction of point sources from urbanized areas, rather than nonpoint sources from agricultural areas that primarily contribute to the Ca-bound P fraction, should be prioritized to alleviate cyanobacterial algal blooms(CyanoHABs) in shallow lakes with sediment P as a potential source to support algae growth. With these important results, we proposed a conceptual model for “P-pumping suction” from sediments to algae to aid in the development of the criteria for sediment P concentrations in shallow lakes.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51579001, 41807398)。
文摘Although point and nonpoint sources contribute roughly equal nutrient loads to lakes,their relative role in supporting algae growth has not been clarified. In this research, we have established a quantitative relationship between algae-available phosphorus(P) and P chemical fractions in sediments;the latter indicates the relative contribution of point versus nonpoint sources. Surface sediments from three large shallow lakes in eastern China, namely, the Chaohu, Taihu and Hongzehu Lakes, were sampled to assess their algaeavailable P and chemically extracted P fractions. The algae-available P primarily comes from iron/aluminium(hydr)oxide-bound P(Fe/Al-bound P), 45% of which is algae-available P. The ratio of Fe/Al-bound P to calcium compound-bound P(Ca-bound P) indicated the relative contribution of point to nonpoint sources, with the point sources contributing the majority of increased Fe/Al-bound P in sediments. Therefore, the reduction of point sources from urbanized areas, rather than nonpoint sources from agricultural areas that primarily contribute to the Ca-bound P fraction, should be prioritized to alleviate cyanobacterial algal blooms(CyanoHABs) in shallow lakes with sediment P as a potential source to support algae growth. With these important results, we proposed a conceptual model for “P-pumping suction” from sediments to algae to aid in the development of the criteria for sediment P concentrations in shallow lakes.
