Tracking the early signals of crude oil in seawater and plankton after a major oil spill in the Red Sea.

Understanding the immediate impacts of oil spills is essential to recognizing their long-term consequences on the marine environment. In this study, we traced the early (within one week) signals of crude oil in seawater and plankton after a major oil spill in October 2019 in the Red Sea. At the time of sampling, the plume had moved eastward, but we detected significant signs of incorporation of oil carbon into the dissolved organic carbon pool, resulting in a 10-20% increase in the ultraviolet (UV) absorption coefficient (a254) of chromophoric dissolved organic matter (CDOM), elevated oil fluorescence emissions, and depletion of the carbon isotope composition (δ13C) of the seawater. The abundance of the picophytoplankton Synechococcus was not affected, but the proportion of low nucleic acid (LNA) bacteria was significantly higher. Moreover, specific bacterial genera (Alcanivorax, Salinisphaera, and Oleibacter) were enriched in the seawater microbiome. Metagenome-assembled genomes (MAGs) suggested that such bacteria presented pathways for growing on oil hydrocarbons. Traces of polycyclic aromatic hydrocarbons (PAHs) were also detected in zooplankton tissues, revealing the rapid entry of oil pollutants into the pelagic food web. Our study emphasizes the early signs of short-lived spills as an important aspect of the prediction of long-term impacts of marine oil spills.

Alteration of phenolic profiles and antioxidant capacities of common buckwheat and tartary buckwheat produced in China upon thermal processing.

BACKGROUND: Buckwheat products are receiving increasing attention because of their high nutritive values and significant health-promoting properties. In the present study, 15 buckwheat products grown in different parts of China were investigated. Representative common or tartary buckwheat samples were further subjected to soaking, roasting, microwave cooking, boiling and steaming treatments. Colorimetric analyses and high-performance liquid chromatography (HPLC) analyses were performed to determine the phenolic profiles and antioxidant capacities of the raw and thermally processed buckwheat samples, respectively. RESULTS: Tartary buckwheat exhibited a remarkably higher total phenolic content (TPC), total flavonoid content (TFC), 2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) compared to common buckwheat, although there were no significant differences between their 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS) free radical scavenging capacity. All thermal treatments, particularly microwave cooking, contributed to the greatest losses of phenolics and antioxidant capacities in the common buckwheat samples, whereas boiling and steaming usually resulted in the lowest losses. For the tartary buckwheat samples, all thermal treatments (except roasting), especially boiling and steaming, led to significant increases in TPC, TFC, DPPH free radical scavenging activity, FRAP and ABTS free radical scavenging capacity. However, HPLC analyses indicated that all thermal treatments, especially microwave cooking, gave rise to the greatest losses of the total content of 14 phenolic acids and three flavonoids, whereas boiling led to the lowest losses. CONCLUSION: Both steaming and boiling treatments are recommended when preparing common or tartary buckwheat food products because they can minimize thermal degradation or promote their phenolic compounds and antioxidant capacities to the greatest extent. © 2019 Society of Chemical Industry.