LAUSR

A total of 60 snow samples from 16 sites across northeastern China were collected from December 2017 to March 2018. The snow samples were analyzed for pH value, major water-soluble ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Ca2+, and Mg2+), and trace elements (Mn, Cr, Cd, Ni, Cu, Zn, Pb, As, and Fe). The results indicated that snow was slightly alkaline (mean pH value 7.54); Ca2+ and SO42- were the major ions, contributing up to 33.87% and 22.72% of the major ions, respectively; Pb was the dominant element, contributing up to 62.84% of the trace elements. Both the concentration of major ions and trace elements peaked in the middle or later period of the entire snow season. Enrichment factor (EF) analysis indicated that ions (NO3-, NH4+, and Ca2+) and trace elements (Pb, As, Cu, and Zn) were severely enriched by anthropogenic activities. Compared with previous studies, which sampled snow from the high altitude and latitude regions, the concentrations of most of the ions and trace elements in this study were found to be 1-3 and 1-4 orders of magnitude higher, respectively, indicating a threat to human health.