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This study aimed to reveal the flavor quality changes of live oysters during different steps of circulation, and optimize the management of live oyster transportation in order to improve the survival quality of oysters. The changes in the types and contents of volatile flavor compounds in Crassostrea gigas sequentially subjected to depuration, induced dormancy and simulated waterless live transportation were investigated using solid phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GC-MS). Results showed that a total of 49 volatile flavor substances were identified in live C. gigas, including aldehydes, ketones, esters, hydrocarbons, alcohols, nitrogen-containing and sulfur-containing heterocyclic compounds. Post-harvest stress had a significant impact on the flavor quality. The content of pleasant flavor compounds was significantly enhanced while the content of irritating odor substances was evidently reduced, and lipid oxidation was significantly alleviated after 24 h of depuration. Lipid oxidation in oysters was increased with waterless live transportation time, and the total amount of volatile flavor substances was slowly accumulated. Odor activity values (OAVs) showed that heptanal, nonanal, (E)-2-nonenal, 4-ethylbenzaldehyde, hexanal, (E)-2-octenal, undecanal, (E)-2-decenal, decanal, (E,E)-2,4-nonadienal and 2-pentyl furan were the key flavor substances of live C. gigas, which could be used as a reference to reflect the physiological status of live oysters. Principal component analysis (PCA) showed that the cumulative contribution of the first three principal components to total variances was 85.6%, allowing a clear distinction between the different stages of circulation. In conclusion, the vitality and flavor substances of C. gigas reach a new level after post-harvest depuration for 24 h, which is more conducive to long-term low temperature and waterless live oyster preservation. Meanwhile, the analysis of volatile components can be used as a method to identify the vitality during the circulation of live shellfish.

The increasing emissions of industrial production and transportation have resulted in serious atmospheric heavy-metal pollution, posing threats to the health of urban residents. In this paper, the bryophyte is recommended to monitor the pollution, which features wide distribution, low cost, and being able to get intuitive results. Thus, a kind of moss (Sphagnum palustre) bag was applied to monitoring the concentrations of atmospheric heavy metal (incl. Cd, Cr, Cu, Pb and Zn) in Guangzhou City, and accordingly the pollution degree and health risks were evaluated. The results obtained from the monitoring showed that in comparison with the pre-exposure to the atmospheric heavy metal pollution, the post-exposure geometric mean values of concentrations of Cd, Cu, Pb and Zn contained in the mosses were 1.2, 2.3, 1.4 and 2.3 times higher than, respectively, however Cr concentration decreased slightly (0.9 times); and in general, the geometric mean values of concentrations of Cd, Cu, Pb and Zn were comparatively high in industrial areas, while in commercial areas, the concentrations of Cu, Pb and Zn were found to be higher than the scenic and residential areas. Principal component analysis (PCA) and cluster analysis (CA) revealed that industrial activities and traffic emission were the main sources of atmospheric heavy metal contamination of Guangzhou City. Following the heavy metal pollution status-quo investigation with moss, four functional areas were assessed using the contamination factor, which indicated that in the monitoring sites showing heavy metals (Cu, Pb, Zn) pollution was high/very-high, the emissions mainly came from coal combustion, industrial metal production and processing activities, while those showing moderate (Cu, Zn) pollution, the pollutants came from traffic sources, and the monitoring sites where heavy metal contamination level was low, were utterly distant from industrial emission sources and traffic pollution sources. In conclusion, the moss bag (Sphagnum palustre) is rather adaptive to monitoring atmospheric heavy metal contamination in urban areas. [ABSTRACT FROM AUTHOR]

Ultra‐high temperature dramatically deteriorates rheological properties and filtration performance of water‐based drilling fluids (WBDFs), especially for a salt‐gypsum formation that greatly restricts the application of WBDFs in ultra‐deep well drilling operations. Hence, the research in this article used an anionic copolymer (DANS) prepared by N, N‐dimethylacrylamide, 2‐acrylamide‐2‐methylpropanesulfonic acid, N‐vinylpyrrolidone, and sodium 4‐styrenesulfonate as an anti‐ultra‐high temperature and anti‐salt contamination filtrate reducer. Due to its multiple bulky cyclic structures in the side chain, DANS exhibits excellent thermal stability in the thermal gravimetric, rheological, and filtration tests. By adding 1.0 wt% DANS, the American Petroleum Institute (API) filtration volume of sodium bentonite‐based fluids (SBT‐BFs) decreased from 56.0 to 9.2 ml after aging at 240°C. Even under both 20 wt% NaCl contamination and 240°C aging, SBT‐BFs with 2.0 wt% DANS could maintain a filtration volume of 9.4 ml, whereas SBT‐BFs without DANS reached a filtration volume of 203.0 ml. The possible filtration control mechanism of DANS was further investigated via the Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), ζ potential, particle size distribution, filter cake micro‐morphology, and transmission electron microscopy (TEM). Confirmed by FTIR and AFM results, the effective adsorption was formed between DANS and bentonite even under a high‐salinity environment. Thus, a firm "dot net" structure formed by bentonite/DANS was observed by TEM, significantly improving the colloidal stability, dispersibility, and filter cake compactness of SBT‐BFs. Finally, by utilizing DANS as the core treatment agent, a high‐density WBDFs system with a temperature resistance of 240°C and a salt‐tolerance of 20 wt% has been successfully prepared. [ABSTRACT FROM AUTHOR]