Responses of phosphorus flux in the sediment-water interface to C:N:P stoichiometry of different sediment components following temperature warming in steppe wetland, China

Purpose The objectives of this study were to (i) determine the ecological stoichiometry of sediment resources, sediment microbial biomass, and sediment enzyme following temperature warming and (ii) explore how P flux in the sediment-water interface cope with the C:N:P stoichiometry following temperature warming in steppe wetland, China. Materials and methods A wetland natural environment simulation device was designed to explore the effect of temperature warming on the P flux in the sediment-water interface. Two simulation modes were designed in this experiment, one under ambient temperature and the other under warming temperature, which was 2.5 degrees C above the ambient temperature. Samples were collected from six wetlands in the Huihe National Nature Reserve, Hulunbeier steppe, China. The experiment was carried out from mid-July to mid-September 2018. During this period, sediments, overlying water, and porewater of all selected wetlands were sampled twice, with an interval of 1 month. Water chemical properties, chemical properties, microbial community properties, and enzymatic activity of sediment were analyzed. ANOVA, redundancy analysis, and partial least squares path model were used for statistical analysis. Results and discussion The stoichiometry of sediment organic carbon (SOC), sediment total nitrogen (TN), and total P in sediment (TP) increased with the change of temperature. The warming exerted no effect on microbial biomass P (MBP), but it significantly increased microbial biomass C (MBC), microbial biomass N (MBN), and alkaline phosphatase activities (APA) in wetland sediment. The P flux in the sediment-water interface under temperature warming was positively affected by water properties, sediment stoichiometric, APA, and sediment microbial properties. However, it was negatively influenced by the stoichiometry of sediment microbial biomass. Moreover, stoichiometric has a greater impact on the P flux in the sediment-water interface, especially the stoichiometric of TN and TP, compared with temperature. Conclusions The stoichiometry of sediment SOC, TN, and TP increased with the change of temperature. The warming exerted no effect on MBP, but it significantly increased MBC, MBN, and APA in wetland sediment. Besides, the P flux in the sediment-water interface under temperature warming was positively affected by water properties, sediment stoichiometric, APA, and sediment microbial properties and negatively affected by the stoichiometry of sediment microbial biomass.