The interactions between olivine dissolution and phytoplankton in seawater: Potential implications for ocean alkalinization.

Ocean alkalinity enhancement, one of the ocean-based CO2 removal techniques, has the potential to assist us in achieving the goal of carbon neutrality. Olivine is considered the most promising mineral for ocean alkalinization enhancement due to its theoretically high CO2 sequestration efficiency. Olivine dissolution has been predicted to alter marine phytoplankton communities, however, there is still a lack of experimental evidence. The olivine dissolution process in seawater can be influenced by a range of factors, including biotic factors, which have yet to be explored. In this study, we cultivated two diatoms and one coccolithophore with and without olivine particles to investigate their interactions with olivine dissolution. Our findings demonstrate that olivine dissolution promoted the growth of all phytoplankton species, with the highly silicified diatom Thalassiosira pseudonana benefiting the most. This was probably due to the highly silicified diatom having a higher silicate requirement and, therefore, growing more quickly when silicate was released during olivine dissolution. Based on the structural characteristics and chemical compositions on the exterior surface of olivine particles, T. pseudonana was found to promote olivine dissolution by inhibiting the formation of the amorphous SiO2 layer on the surface of olivine and therefore enhancing the stoichiometric dissolution of olivine. However, the positive effects of T. pseudonana on olivine dissolution were not observed in the coccolithophore Gephyrocapsa oceanica or the non-silicate obligate diatom Phaeodactylum tricornutum. This study provides the first experimental evidence of the interaction between phytoplankton and olivine dissolution, which has important implications for ocean alkalinization research.

Electrospinning fabrication of covalent organic framework composite nanofibers for pipette tip solid phase extraction of tetracycline antibiotics in grass carp and duck.

In the current study, a novel covalent organic frameworks COF-SCU1 incorporated electrospun nanofibers (PAN@COF-SCU1 nanofibers) was fabricated via a facile electrospinning method and utilized as adsorbent in pipette tip solid-phase extraction (PT-SPE) of tetracycline antibiotics (TCs) from foods. The prepared PAN@COF-SCU1 nanofibers possessed both of the unique characteristics of electrospun nanofibers and COFS-CU1, and thus improving the adsorption capacity of the electrospun nanofibers and preventing the problems of leakage and high pressure caused by directly using the nanosize COFs as adsorbent in PT-SPE. The experiments affected the adsorption and desorption efficiencies, such as the loading ratios of COFS-CU1 in nanofibers, the amount of nanofibers, the matrix pH and desorption solvent, were studied in detail. Eventually, a new pipette tip solid-phase extraction-high performance liquid chromatography (PT-SPE/HPLC) method was proposed for the analysis of three TCs from food. Satisfied linearity for TCs was obtained in the range of 4-70 ng mL-1. The limits of detection and quantification were ranged from 0.6 to 3 ng mL-1 and from 2 to 10 ng mL-1, respectively. The interday and intraday precisions (RSD) were all lower than 9%. The proposed PT-SPE/HPLC method was used to determine TCs residues in grass carp and duck samples for the first time. The results could not only explore the availability of PT-SPE in the extraction of TCs in food samples, but also broadened the potential applications of COFs in sample preparation.