Is There Any Correlation Between Landscape Characteristics and Total Nitrogen in Wetlands Receiving Agricultural Drainages?

Abstract

In the case of increasing fragmentation of wetlands, the study of the relationship between wetland landscape characteristics and total nitrogen (TN) in water is of great significance to reveal the mechanism of wetland water purification. Taking the Naoli River (NR) wetlands in Northeast China as the research object, 10 uniformly distributed sampling sites in the study area were sampled in August 2015 to test the TN concentration and interpret the images of NR wetlands in the same period. Taking the sampling site as the control point, the whole wetlands were divided into 10 regions, and the landscape index of each region was extracted. In order to reveal whether the landscape characteristics are related to the TN concentration in the wetlands water body, the landscape index and the TN concentration in the control point water body were analyzed by correlation analysis, step-by-step elimination analysis and path analysis to reveal whether the landscape characteristics are related to the TN concentration under wetlands receiving agricultural drainages. The results showed that the correlation coefficients between four area indexes or eight shape indexes and TN concentration did not reach a significant correlation level (P > 0.05), indicating that TN removal was not only determined by a single landscape index. The path coefficient of edge density (ED) index is-0.41, indicating that wetland patch connectivity is the primary factor of TN removal, and there is no relationship between the larger patch area and the higher TN removal. The removal of TN in wetlands is restricted by the synergistic effect of landscape area and shape characteristics.

The Impact of Plant Spatial Patterns on Nitrogen Removal in the Naolihe Wetlands of Northeast China

“…In 2015, 450 kg/hm 2 corresponded to paddy fields, and 325 kg/hm 2 corresponded to dry farmland. The concentrations of nitrogen in wetland water have been increasing, primarily due to the discharge of agricultural drainage into the fragmented wetlands [28]. A total of 8 main plant types were recorded in the wetlands, including weeds (WS), Nymphoides peltata-Nymphoides cristatum (N-N), Deyeuxia angustifolia (DA), Typha orientalis (TO), Carex heterolepis (CH), Phragmites australis (PA), Carex appendiculata (CA), and Zizania latifolia (ZL) [29].…”

Water Quality Improvement and Pollutant Removal by Two Regional Detention Facilities with Constructed Wetlands in South Texas

“…At the same time, due to a lack of oxygen in the wetland filtration bed, the removal of ammonia is limited [32]. Significant nitrate reduction is commonly observed in stormwater wetlands, but total nitrogen reduction depends on the species and concentration of incoming nitrogen [32,33]. Several studies have demonstrated that wetland can effectively remove the total nitrogen (TN) with a median removal efficiency of 37%, and that this reduction significantly correlates with the hydrological loading rate and temperature [31].…”