[Volatile Organic Compound Emission Characteristics and Influences Assessment of a Petrochemical Industrial Park in the Pearl River Delta Region].

The petrochemical industry is one of the major emission sources of volatile organic compounds (VOCs). However, the current studies have mostly focused on the identification of the chemical characteristics of non-methane hydrocarbon (NMHC) VOCs species from the petroleum refining sub-sector. Research on the characteristics of VOCs components in oxygenated VOCs (OVOCs) species and other important sub-sectors is still lacking. Therefore, eight enterprises at a petrochemical industrial park in the Pearl River Delta region were carefully selected to represent three major subsectors, namely petroleum refining, synthetic materials, and organic chemicals, for the petrochemical industry. The VOCs (including 22 OVOCs species) from stack emissions and fugitive emissions, as well as nearby sensitive sites, were sampled, and the source reactivity (SR), the thresholds of malodor, and the carcinogenic and non-carcinogenic risks were assessed. The main results were as follows:① the VOCs concentrations of the stack emissions from the petrochemical industrial park were between 0.2-46.3 mg·m-3. The VOCs species were greatly affected by the type of after-treatment technology. A major VOC species emitted from the combustion-based after treatments was formaldehyde, whereas the species emitted from the non-combustion-based equipment were acetone, 1,3-butadiene, acrylic, and isobutane. ② The fugitive VOCs emissions from the petroleum storage tank area were dominated by alkanes, whereas the other fugitive emission sites and the sensitive sites were dominated by OVOCs such as acetone, formaldehyde, and ethyl acetate. ③ The SRs were mainly contributed by OVOCs, aromatics, and olefins, with average proportions of 43.1%, 24.2%, and 21.1%, respectively, with the major species being formaldehyde, acetaldehyde, m/p-xylene, ethylene, and toluene. ④ The malodor appeared both in fugitive emission areas and the sensitive sites. The main odor components were OVOCs such as n-butyraldehyde, propionaldehyde, hexanal, and valeraldehyde. ⑤ The non-carcinogenic risks occurred in the fugitive emission areas and the sensitive sites of resin, alcohol, and aldehyde production, which were mainly caused by OVOCs such as free acetaldehyde, acrolein, and propionaldehyde. No carcinogenic risk was found in any of the sampled sites. This research can provide scientific support for the formulation of priority VOCs species-based precise control strategies in petrochemical industrial parks.

Infrared-active quadruple contrast FePt nanoparticles for multiple scale molecular imaging.

A single nanomaterial with multiple imaging contrasts and functions is highly desired for multiscale theragnosis. Herein, we demonstrate single 1-1.9 µm infrared-active FePt alloy nanoparticles (FePt NPs) offering unprecedented four-contrast-in-one molecular imaging - computed tomography (CT), magnetic resonance imaging (MRI), photoacoustic (PA) imaging, and high-order multiphoton luminescence (HOMPL) microscopy. The PA response of FePt NPs outperforms that of infrared-active gold nanorods by 3- to 5.6-fold under identical excitation fluence and particle concentrations. HOMPL (680 nm) of an isolated FePt NP renders spatial full-width-at-half-maximum values of 432 nm and 300 nm beyond the optical diffraction limit for 1230-nm and 920-nm excitation, respectively. The in vivo targeting function was successfully visualized using HOMPL, PA imaging, CT, and MRI, thereby validating FePt as a single nanomaterial system covering up to four types (Optical/PA/CT/MRI) of molecular imaging contrast, ranging from the microscopic level to whole-body scale investigation.