Effects and prediction of nonpoint source pollution on the structure of aquatic food webs

Abstract

Nonpoint source pollution entering rivers will pollute water quality, degrading the health of aquatic ecosystems. However, owing to the lack of quantitative research on the effects of nonpoint source pollution on the structure of aquatic food webs, there is a lack of quantitative basis for river management. Nonpoint source pollution is not only difficult to control effectively, but also the success rate of water ecological restoration projects is low. With the increasing proportion of nonpoint source pollution in water environmental problems, it is urgent to quantitatively assess and predict the impact of nonpoint source pollution on the structure of food webs. Therefore, this thesis presents a method for quantitatively assessing and predicting the impact of nonpoint source pollution on the structure of food webs through using fuzzy clustering to screen the typical points of the impact of nonpoint source pollution, then using canonical correspondence analysis (CCA) and partial least squares regression analysis to comprehensively filtrate the driving factors affect food web that results in nonpoint source pollution, and then determining the impact of each driving factor on the structure of food webs. Finally, the change trend of food web structure is predicted. The results show that (1) the driving factors that the nonpoint source pollution that affects the food web structure is NH3‐N and chemical oxygen demand (COD). The increase in NH3‐N and COD promotes the growth of phytoplankton, causing the change of the primary productivity of the ecosystem, and ultimately changes the entire food web structure; (2) NH3‐N and COD affect the stability, maturity, connectivity and complexity of the aquatic food web structure. The increase of NH3‐N increases the connectivity and maturity of the food web structure but reduces complexity and stability; the increase of COD increases the connection of the food web structure, while reducing the other three indicators; (3) in some areas with good water quality, aquatic species diversity is high, the relationship of interspecies dietary is complex, food web structure level index is high and the structure of food web is stable. The food web structure in the rainy season will be better than that in the dry season. In some areas with severe water pollution and poor food web structure, the ability of the food web to resist external interference is weak. The food web structure in the rainy season will be worse than that in the dry season owing to rainfall into the river. The methods and conclusions in this treatise can provide a reliable and quantitative scientific basis for river ecosystem management and ecosystem restoration and can improve the success rate of ecological restoration projects.

A Bibliometric Analysis on Nonpoint Source Pollution: Current Status, Development, and Future

“…Table 5 shows the 30 most frequently used author keywords along with their rankings and percentages, which were calculated and ranked using 6-year intervals (except for the first period, which is a 7-year interval) to minimize year-to-year fluctuations. "nonpoint source pollution" and "Water quality" were the most frequently used keywords in NPS pollution articles during the study period, which shows that nonpoint source pollution has a great impact on water quality [5]. Apart from "nonpoint source pollution" and "Water quality", "Phosphorus" and "Nitrogen" were the most frequently used words, confirming that agricultural nonpoint sources have become the main cause of global water quality deterioration [29].…”

“…As we well know, after the point sources have been effectively controlled, nonpoint source pollution (NPS) mainly caused by agricultural activities (such as livestock and poultry breeding, field irrigation, excessive use of pesticides and fertilizers, etc.) becomes the single most important source threatening the utilization of water resources [3][4][5]. NPS pollutants may remain active in the environment for a relatively long period and could cause chronic effects on aquatic ecosystems as well as human health [3,6].…”

Nonpoint Source Pollution (NPSP) Induces Structural and Functional Variation in the Fungal Community of Sediments in the Jialing River, China

“…River sediment is the main site for microbial nutrient metabolism and pollutant degradation. Sediment microorganisms change the aquatic environment conditions through biochemical activities such as assimilation, which further affects the transformation and distribution of nutrients in the sediments and promotes the material cycling of essential elements such as carbon, nitrogen and phosphorus in the sediments (Al-Gabe et al,2014; Liu et al, 2014;Zhao et al, 2021). When pollutant discharge causes changes in the physical and chemical properties of river sediments, the community structure or functions of sediment microorganisms also change accordingly (Xiang et al, 2021).…”