TY - JOUR A1 - Liu, X. A1 - Ran, L. A1 - Lin, W. A1 - Xu, X. A1 - Ma, Z. A1 - Dong, F. A1 - He, D. A1 - Zhou, L. A1 - Shi, Q. A1 - Wang, Y. T1 - Measurement report: Variations in surface SO2 and NOx mixing ratios from 2004 to 2016 at a background site in the North China Plain JO - Atmos. Chem. Phys. Discuss. J1 - ACPD VL - 2022 SP - 1 EP - 23 Y1 - 2022/01/10 PB - Copernicus Publications SN - 1680-7375 UR - https://acp.copernicus.org/preprints/acp-2021-866/ L1 - https://acp.copernicus.org/preprints/acp-2021-866/acp-2021-866.pdf DO - 10.5194/acp-2021-866 ER -