Effects of cadmium addition on net nitrogen mineralization processes in the urban constructed wetland soils of a Chinese delta

AbstractHeavy metal pollution is a serious problem in wetland ecosystems, and the toxicity of heavy metals affects microorganisms, thus influencing the biogeochemical process of nitrogen (N). To investigate the effects of heavy metal cadmium (Cd) pollution on N mineralization in urban constructed wetland soils of the Pearl River Delta, a 40-day aerobic incubation experiment was conducted under three Cd addition treatments [no Cd addition (control), low Cd addition (LCA) and high Cd addition (HCA)]. The results showed that compared with the control, the LCA treatment enhanced the soil N mineralization rate (RM), while the HCA treatment inhibitedRM, with the  averageRM values in the control treatment of 0.40  mg kg−1 day−1, LCA treatments (0.66  mg kg−1 day−1), and HCA treatments (0.21  mg kg−1 day−1). The average ammonification rate values in the LCA treatments ( − 3.15 to 2.25 mg kg−1 day−1) were higher than those in the HCA treatments ( − 2.39 to 0.74 mg kg−1 day−1) and the control treatment ( − 0.68 to 0.90 mg kg−1 day−1) (P <  0.05). However, the nitrification values in the HCA treatments (− 0.37 to 3.36 mg kg−1 day−1) were higher than those in the LCA treatments (0.42 –1.93 mg kg−1 day−1) and the control treatment (0.20 –1.45 mg kg−1 day−1) (P <  0.05). The net N mineralization accumulation generally increased over the entire incubation time in different Cd addition treatment...
Source: Environmental Geochemistry and Health - Category: Environmental Health Source Type: research