Altitudinal patterns and controls of trace metal distribution in soils of a remote high mountain, Southwest China
- 273 Downloads
The aim of this study is to reveal the effects of regional human activity on trace metal accumulation in remote alpine ecosystems under long-distance atmospheric transport. Trace metals (Cd, Pb, and Zn) in soils of the Mt. Luoji, Southwest China, were investigated along a large altitudinal gradient [2200–3850 m above sea level (a.s.l.)] to elaborate the key factors controlling their distribution by Pb isotopic composition and statistical models. The concentrations of Cd, Pb, and Zn in the surface soils (O and A horizons) were relatively low at the altitudes of 3500–3700 m a.s.l. The enrichment factors of trace metals in the surface soils increased with altitude. After normalization for soil organic matter, the concentrations of Cd still increased with altitude, whereas those of Pb and Zn did not show a clear altitudinal trend. The effects of vegetation and cold trapping (CTE) (pollutant enrichment by decreasing temperature with increasing altitude) mainly determined the distribution of Cd and Pb in the O horizon, whereas CTE and bedrock weathering (BW) controlled that of Zn. In the A horizon, the distribution of Cd and Pb depended on the vegetation regulation, whereas that of Zn was mainly related to BW. Human activity, including ores mining and fossil fuels combustion, increased the trace metal deposition in the surface soils. The anthropogenic percentage of Cd, Pb, and Zn quantified 92.4, 67.8, and 42.9% in the O horizon, and 74.5, 33.9, and 24.9% in the A horizon, respectively. The anthropogenic metals deposited at the high altitudes of Mt. Luoji reflected the impact of long-range atmospheric transport on this remote alpine ecosystem from southern and southwestern regions.
KeywordsTrace metals Pb isotopic composition Atmospheric deposition Alpine soils Luoji Mountain
This work was supported by the National Natural Science Foundation of China (41402313), Key Laboratory of Mountain Surface Processes and Ecological Regulation, Chinese Academy of Sciences, Youth Innovation Promotion Association, Chinese Academy of Sciences and IMHE Science Fund for Young Scholars. We are grateful to the fellows from Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, for their assistance in field sampling.
- Cheng, H. R., Zhang, G., Jiang, X. Y., Li, X. D., Liu, X., Li, J., et al. (2007). Organochlorine pesticides, polybrominated biphenyl ethers and lead isotopes during the spring time at the Waliguan Baseline Observatory, Northwest China: Implication for long-range atmospheric transport. Atmospheric Environment, 41, 4734–4747.CrossRefGoogle Scholar
- Gao, Z. Y., Yin, G., Ni, S. J., & Zhang, C. J. (2004). Lead isotope geochemical characteristics in Chengdu. Carsologica Sinica, 23, 267–272.Google Scholar
- Lee, K., Hur, S. D., Hou, S. G., Hong, S. M., Qin, X., Ren, J. W., et al. (2008). Atmospheric pollution for trace elements in the remote high-altitude atmosphere in central Asia as recorded in snow from Mt. Qomolangma (Everest) of the Himalayas. Science of the Total Environment, 404, 171–181.CrossRefGoogle Scholar
- Lee, C. S. L., Li, X. D., Zhang, G., Li, J., Ding, A. J., & Wang, T. (2007). Heavy metals and Pb isotopic composition of aerosols in urban and suburban areas of Hong Kong and Guangzhou, South China—Evidence of the long-range transport of air contaminants. Atmospheric Environment, 41, 432–447.CrossRefGoogle Scholar
- MacKinnon, G., MacKenzie, A. B., Cook, G. T., Pulford, I. D., Duncan, H. J., & Scott, E. M. (2011). Spatial and temporal variations in Pb concentrations and isotopic composition in road dust, farmland soil and vegetation in proximity to roads since cessation of use of leaded petrol in the UK. Science of the Total Environment, 409, 5010–5019.CrossRefGoogle Scholar
- Shotyk, W., Weiss, D., Kramers, J. D., Frei, R., Cheburkin, A. K., Gloor, M., et al. (2001). Geochemistry of the peat bog at Etang de la Gruère, Jura Mountains, Switzerland, and its record of atmospheric Pb and lithogenic trace metals (Sc, Ti, Y, Zr, and REE) since 12,370 14C yr BP. Geochimica et Cosmochimica Acta, 65, 2337–2360.CrossRefGoogle Scholar
- Xu, Y. H., Sun, Q. Q., Yi, L., Yin, X. J., Wang, A. J., Li, Y. H., et al. (2014). The source of natural and anthropogenic heavy metals in the sediments of the Minjiang River Estuary (SE China): Implications for historical pollution. Science of the Total Environment, 493(15), 729–736.CrossRefGoogle Scholar
- Yan, N., Zhang, J., Yuan, W. M., Gong, Q. J., Wang, Q. F., & Luo, J. H. (2013). Characteristics of isotopic geochemistry andmetallogenesis of the Gala gold deposit in Ganzi-Litang suture zone, western Sichuan Province, China. Acta Petrologica Sinica, 29, 1347–1357.Google Scholar
- Zheng, J., Tan, M. G., Shibata, Y., Tanaka, A., Li, Y., Zhang, G. L., et al. (2004). Characteristics of lead isotope ratios and elemental concentrations in PM10 fraction of airborne particulate matter in Shanghai after the phase-out of leaded gasoline. Atmospheric Environment, 38, 1191–1200.CrossRefGoogle Scholar