Active Biomonitoring of Atmospheric Element Deposition in the Heating Period of Tangshan Using Ramalina sinensis

Abstract

Tangshan is known as a typical heavy industrial city with serious atmospheric pollution. It suffers the most serious atmospheric pollution during the winter heating period. This study aims to explore the level and spatial distribution of atmospheric element deposition in the study area and validate the suitability of Ramalina sinensis ( RSI ) as an active biomonitor in North China cities. RSI was transplanted to Tangshan in winter (Dec. 2016-Mar. 2017) and exposed for 17 weeks. The concentration of 51 elements was tested using an ICP-MS (inductively coupled plasma mass spectrometer). The results showed that the exposure concentration of all elements but Ag was significantly higher than the background value. Principal component analysis (PCA) showed that K, P, and Rb were separated into the group G5, and these nutrients have a lower level of bioaccumulation than other groups. The remaining 47 elements were classified into groups G1 (Al, Be, Co, Cr, Cs, Ge, Li, Nb, Ni, Si, Th, Ti, U, V, and 16 rare earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) of crustal origin, G2 (Ca, Cd, Cu, Mg, Mn, Mo, S, Sb, Sr, and Zn) and G3 (Bi, Pb, and Sn) of atmospheric origin, and G4 (As, Fe, Se, and Tl) of crustal-atmospheric origin. The overall bioaccumulation in Tangshan is moderate (PLI zone = 2.010 for the combined groups G1-4), with the highest bioaccumulation level (high to severe) for the atmospheric group G2. The most concerned elements are Ca and S, which are of high bioaccumulation at the regional scale. All element groups show a similar spatial pattern characterized by decreasing atmospheric deposition from east to west and from rural to urban areas. These results indicate that RSI is a good active biomonitor for most elements, barring some nutrients. The importance of G2 elements should be emphasized as an indicator of anthropogenic emissions in lichen-active biomonitoring techniques in North China cities. The study area experienced a certain degree of atmospheric pollution, contributed mainly by the frequent industrial and agricultural activities and coal combustion for heating in the east of the city and the rural areas around. This study is the first to monitor atmospheric deposition in industrial cities in North China using the active lichen biomonitoring method.