Epilithic moss as a bio-monitor of atmospheric N deposition in South China

Abstract

To assess the utility of epilithic mosses as bio-monitors of atmospheric N deposition in Southern China, single and multiple moss species were collected in forested, agricultural, suburban, urban, and sewage landfill habitats, and then analyzed for N tissue content and δ 15 N values. About 83% of all the moss samples showed an N content of >2.0% and significant differences were only found between forests and the other four kinds of areas. But no significant differences were found between single and multiple moss species at each area. Six previously reported relationships between N deposition and N contents of single moss species and four of multiple moss species were assessed to be used for estimation of N deposition. In the selected areas of South China, the average of N deposition estimated using the equations of single and multiple moss species was 30.8 to 41.6 kg N ha -1 yr -1 and 26.0 to 34.9 kg N ha -1 yr -1, respectively. And the former showed much larger standard deviation of N deposition than the latter, suggesting that the equations of multiple moss species might be preferred to be used for estimation of N deposition. There were significant differences in moss δ 15 N values in different kinds of areas except between urban areas and sewage landfills, where mosses were most 15 N-depleted (-10% to-2%, reflecting sewage-derived NH y). For both single and multiple moss species, those in suburban areas were between-5% to-1%, reflecting the mixing of sewage-derived and soil-derived NH y. The δ 15 N values of mosses in forested (-3% to +3%) and agricultural areas (-1% to +1%) indicated soil-derived NH y and chemical fertilizer. Copyright 2011 by the American Geophysical Union.