Assessing Precipitation Redistribution and Chemical Dynamics in Beijing: Impact of Three Typical Tree Species

Three tree species of Amygdalus triloba (At), Robinia pseudoacacia (Rp) and Juniperus juniper (Jj) were used as research objects, and self-made through fall and stem flow collection devices were used to collect and analyze through fall and stem flow in July of 2021. NH₄⁺, Ca²⁺, K⁺, Cl^-, NO₃^- and SO₄^2- were the main components of precipitation ions. During the continuation of the precipitation process, the concentrations of most of the tested ions in the through fall and stem flow of At, through fall of Rp, and stem flow of the Jj were correlated with the duration of the rainfall. During the rainfall duration, the concentrations of most of the tested ions in the through fall and stem flow of At, the through fall of Rp and the stem flow of Jj were correlated with the duration. The K⁺, Mg²⁺, and Ca²⁺ ions associated with stagnant dust in the through fall and trunk stem flow of At were significantly different from those of the other two species. Changes in Ca²⁺, Mg²⁺, Cl^-, and NO₃^- concentrations after precipitation drenching Jj branches and trunks were greater than those of At and Rp. The main cations and anions in both through fall and stem flow were Ca²⁺, K⁺ and NO₃^-, which may be related to dust and automobile exhaust pollution in the experimental area.