Emission characteristics of CO, NOx, SO2and indications of biomass burning observed at a rural site in eastern China

T Wang,D R Blake,X M Yu,T F Cheung,Y S Li

doi:10.1029/2001jd000724

Abstract

Atmospheric O3, CO, SO2, and NOy* (NOy* ≈ NO + NO2+ PAN + organic nitrates + HNO3+ N2O5+ ⋯) were measured in 1999–2000 at a rural/agricultural site in the Yangtze Delta of China. In this paper we analyze the measurement results to show the emission characteristics of the measured gases and to infer relevant emission ratios. Positive correlations were found between CO and NOy* with a slope (Δ[CO]/Δ[NOy*]) of 36 (ppbv/ppbv) for the winter and nighttime measurements. The ratio is considerably larger than that (≈10 ppbv/ppbv) observed in the industrialized countries. The highest CO/NOy* ratio (30–40 ppbv/ppbv) occurred in September–December 1999 and June 2000. The good correlation between CO and the biomass burning tracer CH3Cl and the lack of correlation with the industrial tracer C2Cl4suggests that the burning of biofuels and crop residues is a major source for the elevated CO and possibly for other trace gases as well. The average SO2to NOy* ratio was 1.37 ppbv/ppbv, resulting from the use of relatively high‐sulfur coals in China. The measured SO2/NOy* and ΔCO/ΔNOy* were compared with the respective ratios from the current emission inventories for the study region, which indicated a comparable SO2/NOxemission ratio but a large discrepancy for CO/NOx. The observed CO to NOy* ratio was more than 3 times the emission ratio derived from the inventories, indicating the need for further improvement of emission estimates for the rural/agricultural regions in China. Additional research will be needed to study the implications of rural emissions to atmospheric chemistry and climate on both regional and global scales.

Highlights

[1] Atmospheric O3, carbon monoxide (CO), SO2, and NO*y (NO*y % NO + NO2 + peroxyacetyl nitrate (PAN) + organic nitrates + HNO3 + N2O5 + ...) were measured in 1999–2000 at a rural/agricultural site in the Yangtze Delta of China
This present paper focuses on the emission patterns of CO, NOx, and SO2 observed at this rural site
CO and NO*y showed good positive correlations with an overall slope of 36 ppbv/ppbv, which is substantially larger than those (%10 ppbv/ppbv) found at rural sites in industrialized nations

Summary

Introduction

[2] In the past two decades, China has experienced phenomenal urban and industrial development. The first large-scale field study of ozone (O3) and related gases was carried out in 1994 – 1995 at several rural sites in eastern China [Peng et al, 1997; Luo et al, 2000]. The overall seasonal variations of the measured gases and the ozone relationships with NO*y and CO have been shown by Wang et al [2001a] This present paper focuses on the emission patterns of CO, NOx, and SO2 observed at this rural site. [8] SO2 was measured by a pulsed UV fluorescence (TEI, model 43S), with a detection limit of 0.06 ppbv and 2-s precision of 3% for ambient levels of 10 ppbv (2-min average). Daytime a Maximum 1-hour O3 values in each month are shown. b Daytime, 0800-1959 LT; nighttime, 2000-0759 LT

Results and Discussion

Standard Deviation

Measurement inferreda

Summary and Conclusions