## 1 Introduction  
All environmental problems are social problems [1]. Rapid social development increases the emission quantity of pollutants [2; 3; 4]. Nowadays, the water environment pollution of rivers and lakes has become an urgent ecological and environmental problem that needs to be solved [5; 6]. Among them, non-point source pollution of agriculture is hard to control and involves a wide range due to its characteristics of dispersive, covert, random, latent, accumulated, and ambiguous [7; 8; 9; 10]. Non-point source pollution of agriculture has been a significant source of pollution that affects water quality [11; 12; 13]. In China, pesticides and fertilizers in agriculture cause considerable pollution to surface waters [14]. In particular, the excessive use of nitrogen and phosphorous can contaminate water bodies by leaching and surface runoff. In agricultural non-point source pollution entering the surface water, riparian herbaceous vegetation buffer strips significantly affect elimination as an ecological link between terrestrial and aquatic ecosystems [15]. Riparian herbaceous vegetation buffer strips increase the biodiversity of ecosystems and retard sediment [16; 17]. In terms of ecological functions, they protect the river water environment, maintain water quality, and improve biodiversity. Concurrently, riparian herbaceous vegetation buffer strips can significantly contribute to controlling non-point pollution by absorption, increasing dissolved oxygen, providing biological habitats, loosening soil, retarding runoff, and adjusting microclimate [18; 19]. Due to these reasons, riparian herbaceous vegetation buffer strips are used to reduce non-point source pollution in water bodies [20; 21; 22]. In recent years, some researchers found that riparian herbaceous vegetation buffer strips can significantly reduce total nitrogen (TN), total phosphorus (TP), or other pollutants through physical, chemical, and biological actions (e.g., intercept, filter, and absorb) [23; 24; 25]. Further, groups of papers are devoted to the factors influencing riparian herbaceous vegetation buffer strips' non-point source pollution reduction [24; 25; 26; 27]. The main influencing factors are filter conditions, pollutants concentration, and vegetation configurations [28]. For instance, total suspended solids (TSS) interception and the reduction of other pollutants mainly happen at the front end of riparian herbaceous vegetation buffer strips. This is because herbaceous vegetation that grows intensively and covers the surface can retard runoff; intercept runoff pollutants; and degrade, absorb, and deposit pollutants effectively. Riparian herbaceous vegetation buffer strips can significantly block TP of surface runoff better than artificial forest land and potentially reduce NO\({}_{3}\)-N by 55-90% in outflows from the subbasin under average rainfall conditions [29; 30; 31]. The broad and gentle bank slope and the riparian herbaceous vegetation buffer strips have relatively better effects on the interception of pollutants [32]. However, the above studies were limited to the mechanism of single pollutant elimination by a single plant species or groups of plants or focused on qualitative analysis of the effect of buffer strips for retarding runoff and reducing pollutant concentrations. Relatively few researchers have focused on the combined reduction ability of different riparian herbaceous vegetation buffer strips for multiple pollutants [33; 34]. This study intends to compare and analyze the prevention and control of non-point source pollution in surface runoff using different riparian herbaceous vegetation buffer strips. Riparian herbaceous vegetation buffer strips can simultaneously remove multiple types of water pollutants, but the actual effectiveness of their removal is greatly influenced by natural conditions. Therefore, the selection of herbaceous vegetation species in this study is based on the actual situation in the research area [35; 36].