RESUMO
In order to explore the pollution characteristics, seasonal variations, and sources of water-soluble inorganic ions (WSIIs) in PM2.5 in Zhengzhou, PM2.5 samples were seasonally collected from December 2020 to October 2021; then, combining gaseous pollutants (SO2, NO2, and O3) and meteorological parameters (temperature and relative humidity), nine WSIIs (NO3-, NH4+, SO42-, Ca2+, K+, Na+, Mg2+, F-, and Cl-) were analyzed. The results showed that the annual average concentration of the total water-soluble ions (TWSIIs) was (39.34±21.56) µg·m-3for the four seasons, showing obvious seasonal variations with the maximum value in winter and the minimum value in summer. Annual PM2.5 was slightly alkaline in Zhengzhou, and NH4+ most likely existed in the form of NH4NO3 and (NH4)2SO4. The average sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were 0.35 and 0.19, respectively, indicating that SO42- and NO3- mainly derived from secondary formation. The main potential source regions of WSIIs obtained by the concentration weight trajectory (CWT) model showed temporal and spatial variations. The significant sources of WSIIs based on principal component analysis (PCA) were dust, secondary generation, combustion, and industrial activities, which were obviously influenced by wind direction and speed in Zhengzhou.
RESUMO
Some current-use pesticides are chiral and have nonsuperimposable mirror images called enantiomers that exhibit identical physical-chemical properties but can behave differently when in contact with other chiral molecules (e.g., regarding degradation and uptake). These differences can result in variations in enantiomer presence in the environment and potentially change the toxicity of pesticide residues. Several current-use chiral pesticides are applied in urban and agricultural areas, with increased potential to enter watersheds and adversely affect aquatic organisms. The present study describes a stereoselective analytical method for the current-use pesticides fipronil, cis-bifenthrin, cis-permethrin, cypermethrin, and cyfluthrin. We show use of the method by characterizing enantiomer fractions in environmental sample extracts (sediment and water), and laboratory-dosed fish and concrete extracts previously collected by California organizations. Enantiomer fractions for most environmental samples are the same as racemic standards (equal amounts of enantiomers, enantiomer fraction = 0.5) and therefore are not expected to differ in toxicity from racemic mixtures typically tested. In laboratory-derived samples, enantiomer fractions are more frequently nonracemic and favor the less toxic enantiomer; permethrin enantiomer fractions range from 0.094 to 0.391 in one type of concrete runoff and enantiomer fractions of bifenthrin in dosed fish range from 0.378 to 0.499. We use enantiomer fractions as a screening tool to understand environmental exposure and explore ways this uncommon measurement could be used to better understand toxicity and risk. Environ Toxicol Chem 2018;37:99-106. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.