Polycyclic aromatic compounds (PAHs, oxygenated PAHs, nitrated PAHs and azaarenes) in soils from China and their relationship with geographic location, land use and soil carbon fractions

Benjamin A Musa Bandowe; Chong Wei; Yongming Han; Junji Cao; Changlin Zhan; Wolfgang Wilcke

doi:10.1016/j.scitotenv.2019.07.022

Polycyclic aromatic compounds (PAHs, oxygenated PAHs, nitrated PAHs and azaarenes) in soils from China and their relationship with geographic location, land use and soil carbon fractions

Sci Total Environ. 2019 Nov 10:690:1268-1276. doi: 10.1016/j.scitotenv.2019.07.022. Epub 2019 Jul 3.

Authors

Benjamin A Musa Bandowe¹, Chong Wei², Yongming Han³, Junji Cao⁴, Changlin Zhan⁵, Wolfgang Wilcke⁶

Affiliations

¹ Institute of Geography and Geoecology, Karlsruhe Institute of Technology (KIT), Reinhard-Baumeister-Platz 1, 76131 Karlsruhe, Germany. Electronic address: benjamin.bandowe@mpic.de.
² Key Laboratory of Aerosol Chemistry and Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Shanghai Carbon Data Research Center (SCDRC), CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China. Electronic address: weic@sari.ac.cn.
³ Key Laboratory of Aerosol Chemistry and Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
⁴ Key Laboratory of Aerosol Chemistry and Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
⁵ Key Laboratory of Aerosol Chemistry and Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Environmental Science and Engineering College, Hubei Polytechnic University, Huangshi 435003, China.
⁶ Key Laboratory of Aerosol Chemistry and Physics (KLACP), State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China. Electronic address: wolfgang.wilcke@kit.edu.

PMID: 31470489
DOI: 10.1016/j.scitotenv.2019.07.022

Abstract

The assessment of risks arising from polycyclic aromatic compounds (PACs), particularly from the polar PACs [azaarenes (AZAs), oxygenated PAHs (OPAHs), nitrated PAHs (NPAHs)] requires us to understand the drivers of their spatial distribution. We determined the concentrations of 29 PAHs, 4 AZAs, 15 OPAHs and 11 NPAHs and their relationships with land use (urban vs. rural and forest vs. agriculture), climate (Qinghai-Tibetan plateau, temperate, sub tropical and tropical) and three C fractions (soil organic C, char, soot) in 36 mineral topsoils (0-5 cm) of China. The average concentrations±standard deviation of the Σ29PAHs, Σ16PAHs, Σ4AZAs, Σ15OPAHs and Σ11NPAHs were 352 ± 283, 206 ± 215, 5.7 ± 3.7, 108 ± 66.8 and 3.2 ± 3.4 ng g^-1, respectively. PAH, OPAH, NPAH and AZA concentrations were frequently not correlated within or across the regions reflecting different sources and turnover of PAHs and their derivatives. Temperate urban soils showed the highest and tropical rural soils the lowest concentrations of PACs. Forest soils had higher PACs concentrations than agricultural soils. Longitude correlated positively with the ∑29PAHs concentrations, because of increasing emissions of PAHs from East to West. The tropical and plateau regions with the lowest PAH concentrations, were dominated by low molecular weight PAHs (LMW-PAHs) with LMW/high molecular weight (HMW)-PAHs ratios >1, while the other two climatic regions with more industrial sites showed the opposite. Latitude correlated with NPAHs likely because of enhanced formation by photochemical reactions during transport in the atmosphere. The concentrations of the ∑29PAHs, ∑4AZAs, ∑15OPAHs, ∑11NPAHs and their individual components were only occasionally correlated with those of carbon fractions (soil organic C, soot and char) suggesting a small role of soil C pool properties in driving PACs concentrations. Our results demonstrate that the strongest drivers of PACs concentrations are land use and distance to PAC emission sources followed by climate and size and properties of the soil organic C pool.

Keywords: Carbon fractions (organic, soot, char); Climate zones of China; Environmental fate; PACs patterns; Photochemical transformation.