Developments and improvements to the particle-into-liquid sampler (PILS) and its application to Asian outflow studies.

摘要

Particle chemical composition provides insights into aerosol sources and atmospheric transformation processes. In this research, a method for online measurements of fine aerosol ionic constituents was developed and improved, and applied to field studies.; Developments and improvements to the prototype Particle-Into-Liquid Sampler-Ion Chromatograph (PILS-IC) produce a more robust instrument, which allows sample flow rate at 15 l min-1. Eight inorganic aerosol components can be measured within 4 minutes for airborne studies and some light organic acids can also be measured within 15 minutes for ground-based studies. Limits of Detection (LOD), are approximately 50 ng m-3 for the cations and ∼10 ng m-3 for the anions.; Two PILS-ICs were deployed on Transport and Chemical Evolution over the Pacific (TRACE-P) and the Aerosol Characterization Experiment-Asia (ACE-Asia) airborne studies in spring 2001. Intercomparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r2 of 0.95), but were systematically different by 10% +/- 5%. Higher concentrations were generally observed on the aircraft with a low turbulence inlet and shorter inlet-to-instrument transmission tubing. Intercomparison between PILS-IC and micro-orifice impactor (MOI) on the same aircraft showed that for sulfate, they were within 14% +/- 6% and correlated with an r2 of 0.87.; PILS's rapid measurements were capable of identifying and characterizing plumes of various mixtures of emissions. Fine particle water-soluble potassium (K+) was confirmed to be a unique bio-smoke tracer, and its prevalence throughout the TRACE-P experiment indicated that approximately 20% of the Asian outflow plumes were influenced by biosmoke emissions. Ratios of K+/SO42- were used to provide an estimate of relative contributions of bio-smoke emissions to the mixed plumes. On average, it is estimated that bio-smoke contributes approximately 35 +/- 18% to the measured fine inorganic aerosol mass in the mixed TRACE-P plumes intercepted north of 25°N latitude.; The volatility loss of ammonium within the PILS-IC is investigated. Field study data and laboratory experiments suggest that the PILS under-measures ammonium by 13--16%. Theoretical calculation indicates that the PILS can measure 80--90% of the sampled ammonium particles.