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
An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variation...An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variations in event mean concentrations（EMCs） of pollutants from a given agricultural watershed during rainstorms were only attributable to the rainfall pattern.Fifty one sets of EMC values were obtained from nine different watersheds located in the rural areas of Korea, and these data were used to develop predictive tools for the EMCs in rainfall runoff. The results of statistical tests of these formulas show that they are fairly good in predicting actual EMC values of some parameters, and useful in terms of calculating pollutant loads for any rainfall event time span such as daily, weekly, monthly, and yearly. This model was further checked in for its field applicability in a reservoir receiving stormwater after a cleanup of the sediments, covering 17 consecutive rainfall events from 1 July to 15 August in2007. Overall the predicted values matched the observed values, indicating the feasibility of this empirical tool as a simple and useful solution in evaluating timely distribution of nonpoint source pollution loads from small rural watersheds of Korea.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.
基金supported by the Eco-Star Aquatic Ecosystem Restoration Research Program, KoreaExtensive sampling programs were supported by the Sustainable Water Resource Development Research Fund, Korea
文摘An integrated approach to easily calculate pollutant loads from agricultural watersheds is suggested and verified in this research. The basic concepts of this empirical tool were based on the assumption that variations in event mean concentrations（EMCs） of pollutants from a given agricultural watershed during rainstorms were only attributable to the rainfall pattern.Fifty one sets of EMC values were obtained from nine different watersheds located in the rural areas of Korea, and these data were used to develop predictive tools for the EMCs in rainfall runoff. The results of statistical tests of these formulas show that they are fairly good in predicting actual EMC values of some parameters, and useful in terms of calculating pollutant loads for any rainfall event time span such as daily, weekly, monthly, and yearly. This model was further checked in for its field applicability in a reservoir receiving stormwater after a cleanup of the sediments, covering 17 consecutive rainfall events from 1 July to 15 August in2007. Overall the predicted values matched the observed values, indicating the feasibility of this empirical tool as a simple and useful solution in evaluating timely distribution of nonpoint source pollution loads from small rural watersheds of Korea.
