Assessing threshold values for eutrophication management using Bayesian method in Yuqiao Reservoir, North China

Abstract

The eutrophication problem of drinking water source is directly related to the security of urban water supplication, and phosphorus has been proved as an important element to the water quality of the most northern hemisphere lakes and reservoirs. In the paper, 15-year monitoring records (1990∼2004) of Yuqiao Reservoir were used to model the changing trend of the total phosphorus (TP), analyze the uncertainty of nutrient parameters, and estimate the threshold of eutrophication management at a specific water quality goal by the application of Bayesian method through chemical material balance (CMB) model. The results revealed that Yuqiao Reservoir was a P-controlled water ecosystem, and the inner concentration of TP in the reservoir was significantly correlated with TP loading concentration, hydraulic retention coefficient, and bottom water dissolved oxygen concentration. In the case, the goal of water quality for TP in the reservoir was set to be 0.05 mg L(-1) (the third level of national surface water standard for reservoirs according to GB3838-2002), management measures could be taken to improve water quality in reservoir through controlling the highest inflow phosphorus concentration (0.15∼0.21 mg L(-1)) and the lowest DO concentration (3.76∼5.59 mg L(-1)) to the threshold. Inverse method was applied to evaluate the joint manage measures, and the results revealed that it was a valuable measure to avoid eutrophication by controlling lowest dissolved oxygen concentration and adjusting the inflow and outflow of reservoir.

Identification and Quantification of Physicochemical Parameters Influencing Chlorophyll-a Concentrations through Combined Principal Component Analysis and Factor Analysis: A Case Study of the Yuqiao Reservoir in China

“…The phosphorus control variable acts as the first influencing factor, which agrees with the research of Li et al [43] and other research indicating that the Yuqiao Reservoir is phosphorus controlled. The nitrogen-phosphorus ratio is negatively correlated with chl-a concentrations, and it is helpful to show that the effect of phosphorus is higher than that of nitrogen.…”

“…For example, Liu et al [32] studied the relationship between environmental physicochemical parameters and chl-a concentrations in the Yuqiao Reservoir from 2003 to 2005, and found that T, COD, and NH 4 + had the most influence on chl-a concentrations. Furthermore, phosphorus was found to significantly affect chl-a concentrations in the Yuqiao Reservoir, which is consistent with the conclusion that the Yuqiao Reservoir has been gradually transformed into a phosphorus-controlled environment [43]. Therefore, it is necessary to study the sources of phosphorus and control measures for pollution sources.…”

“…Zhao and Cui [31] found that turbidity, chl-a, alkalinity, and hardness were the main parameters influencing seasonal variability of water ecosystems in northern China. Liu et al [43] suggested that air pressure and pH were the main parameters affecting chl-a levels in a study conducted between 1999 and 2012. Thus, the choice of environmental parameters will have an impact on the results, depending on the period and seasons of study.…”

“…Because DO has a negative correlation with chl-a, mechanical and chemical reagents could be used to increase the dissolved oxygen content of the Yuqiao Reservoir, thereby reducing chl-a levels. Physical parameters also have an impact on endogenous nutrients, which indirectly affect chl-a concentrations [37,43,51]. A study from Cong et al [52] showed that low DO and high pH have a synergistic effect on the release of phosphorus in sediments, and that the release of nitrogen is mainly affected by DO.…”

Chlorophyll-A Prediction of Lakes with Different Water Quality Patterns in China Based on Hybrid Neural Networks

“…Due to the cultural significance of DML, DL, and XL, intense eutrophication was occurring due to human activities as the regions have experienced rapid economic development and environmental change [35]. YQR is the main water source for industrial, agricultural, and daily use in Tianjin, and has played an important role in the economic development of Tianjin City [36]. The TLI value of YQR was approaching the minimum eutrophic range and the eutrophication risk would induce adverse effects on human health.…”