Hydrological management for improving nutrient assimilative capacity in plant-dominated wetlands: A modelling approach

Abstract

Wetland eutrophication is a global environmental problem. Besides reducing pollutant emissions, improving nutrient assimilative capacity in wetlands is also significant for preventing eutrophication. Hydrological management can improve nutrient assimilative capacity in wetlands through physical effects on the dilution capacity of water body and ecological effects on wetland nutrient cycles. The ecological effects are significant while were rarely considered in previous research. This study focused on the ecological effects of hydrological management on two crucial nutrient removal processes, plant uptake and biological denitrification, in plant-dominated wetlands. A dual-objective optimization model for hydrological management was developed to improve wetland nitrogen and phosphorus assimilative capacities, using upstream reservoir release as water regulating measure. The model considered the interactions between ecological processes and hydrological cycles in wetlands, and their joint effects on nutrient assimilative capacity. Baiyangdian Wetland, the largest freshwater wetland in northern China, was chosen as a case study. The results found that the annual total assimilative capacity of nitrogen (phosphorus) was 4754 (493) t under the optimal scheme for upstream reservoir operation. The capacity of nutrient removal during the summer season accounted for over 80% of the annual total removal capacity. It was interesting to find that the relationship between water inflow and nutrient assimilative capacity in a plant-dominated wetland satisfied a dose-response relationship commonly describing the response of an organism to an external stressor in the medical field. It illustrates that a plant-dominated wetland shows similar characteristics to an organism. This study offers a useful tool and some fresh implications for future management of wetland eutrophication prevention.

Optimizing environmental flow and macrophyte management for restoring a large eutrophic lake‐marsh system

“…In this study, nutrient and water cycle modelling in a wetland is based on mass balance theory (Xu, Yang, et al, 2016). Nutrient balance calculation is an effective way to determine the monthly variation in the mass of nutrients in a water body.…”

“…Because of the alkalescent water environment in the Wetland Baiyangdian, neither ammonia volatilization nor chemo‐denitrification are significant (Zhao et al, 2012). Monthly variations in TN and TP amounts in the water can be calculated through the following equations (Xu, Yang, et al, 2016). where TN t and TP t denote the TN and TP amounts (t) in the wetland water during month t (1–12), respectively; TN in, t and TP in, t denote the TN and TP amounts (t) that flow into water during month t ; TN o, t and TP o, t denote the TN and TP amounts (t) discharged through outflow; TN e, t , TN p, t , and TN b, t denote the TN amount (t) removed from water through retention in sediment, macrophyte uptake, and biological denitrification, respectively; TP e, t and TP p, t denote the TP amount (t) removed through retention in sediment and macrophyte uptake, respectively.…”

“…Thus, the average TN and TP concentrations within the system are calculated by dividing the nutrient amount with the water volume. Based on nutrient and water balances in the wetland, water quality constraints can be defined as follows (Xu, Yang, et al, 2016).…”

“…On the other hand, particular characteristics associated with specific aquatic systems will also influence phytoremediation performance, and management strategies should therefore pay more attention to these characteristics (Singh & Oldham, 2017; Q. Zhang, Dong, Yang, Odgaard, & Jeppesen, 2019). Hydrological conditions are among the most important characteristics of aquatic systems (Naja, Childers, & Gaiser, 2017; Xu, Yang, Yin, Cai, & Sun, 2016). Where phytoremediation is proposed as a restoration measure, the management of hydrological conditions will inevitably be important because macrophytes require a suitable water depth for growth (Pagter, Bragato, & Brix, 2005).…”

Wetlands for Wastewater Treatment

“…A dual-objective reservoir operation optimization model was used to improve nutrients (mainly N and P) assimilative capacities in downstream plant-dominated wetlands (Xu, Yang, et al, 2016 has been used to study the response of hourly and daily sudden loads in a HFCWs (Rizzo and Langergraber, 2016). The basis of this model is the causal-effect relationships, such as human activities, human unsustainable consumption modes, or economic systems exert some pressures on the environment (Sun, Lin, et al, 2016).…”