Tetracycline (TC) is one of the most widely used antibiotics with significant impacts on human health and thus it needs appropriate approaches for its removal. In the present study, we evaluated the performance and co...
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Tetracycline (TC) is one of the most widely used antibiotics with significant impacts on human health and thus it needs appropriate approaches for its removal. In the present study, we evaluated the performance and complete pathway of the TC electrochemical oxidation on a Ti/Ti4O7 anode prepared by plasma spraying. Morphological data and composition analysis indicated a compact coating layer on the anode, which had the characteristic peaks of Ti4O7 as active constituent The TC electrochemical oxidation on the Ti/Ti4O7 anode followed a pseudo-first-order kinetics, and the TC removal efficiency reached 95.8% in 40 min. The influential factors on TC decay kinetics included current density, anode-cathode distance and initial TC concentration. This anode also had high durability and the TC removal efficiency was maintained over 95% after five times reuse. For the first time, we unraveled the complete pathway of the TC electrochemical oxidation using high-performance liquid chromatograph (HPLC) and gas chromatograph (GC) coupled with mass spectrometer (MS). center dot OH radicals produced from electrochemical oxidation attack the double bond, phenolic group and amine group of TC, forming a primary intermediate (m/z = 461), secondary intermediates (m/z = 432, 477 and 509) and tertiary intermediates (rn/z = 480, 448 and 525). The latter were further oxidized to the key downstream intermediate (m/z = 496), followed by further downstream intermediates (rn/z = 451, 412, 396, 367, 351, 298 and 253) and eventually short-chain carboxylic acids. We also evaluated the toxicity change during the electrochemical oxidation process with bioluminescent bacteria. The bioluminescence inhibition ratio peaked at 10 min (55.41%), likely owing to the high toxicity of intermediates with m/z = 461, 432 and 477 as obtained from quantitative structure activity relationship (QSAR) analysis. The bioluminescence inhibition ratio eventually decreased to 16.78% in 40 min due to further transformation
Thallium (TI) is a very toxic heavy metal. As a part of ongoing investigations, the mobility, sources and fate of TI were investigated for sediments from a watershed in the northern part of the Pearl River, South Chin...
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Thallium (TI) is a very toxic heavy metal. As a part of ongoing investigations, the mobility, sources and fate of TI were investigated for sediments from a watershed in the northern part of the Pearl River, South China, whose catchment has been seriously impacted by large-scale Pb Zn smelting activities onshore. A wide dispersion of severe TI contamination was observed throughout the depth profiles. A modified IRMM (Institute for Reference Materials and Measurements, Europe) sequential extraction procedure of a selected depth profile uncovered an exceptionally high enrichment of TI in geochemically-mobile fractions (i.e., weak-acid-exchangeable, reducible and oxidizable fractions), on average 5.94 +/- 2.19 mg/kg (74.6% +/- 5.1% of the total TI content) not only in the surface sediments but also in deep sediments. The proximal quantitative source apportionment using Pb isotopic fingerprinting technique indicated that a majority (80%-90%) of TI contamination along the depth profiles is anthropogenically derived from the Pb Zn smelting wastes. The results highlight the pivotal role of smelting activities in discharging huge amounts of geochemically-mobile TI to the sediments down to approximately 1 m in length, which is quantitatively evidenced by Pb isotopic tracing technique. Lead isotopes combined with distribution of TI and Pb contents identified a potential marker for a point source from the Pb Zn smelter in the river catchment, which also provides a theoretical framework for source apportionment of metal contamination in a larger river/marine system and in other sulfide mining/smelting areas likewise. (C) 2018 Elsevier Ltd. All rights reserved.
Norgestrel (NGT) is a synthetic progestin used in human and veterinary medicine. Adult female mosquitofish were exposed to NGT for 42 d at 377 ng L-1. The fin morphology and the liver transcriptome were assessed. NGT ...
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Norgestrel (NGT) is a synthetic progestin used in human and veterinary medicine. Adult female mosquitofish were exposed to NGT for 42 d at 377 ng L-1. The fin morphology and the liver transcriptome were assessed. NGT exposure increased ray 4:6 length ratio. As compared to the control, NGT treatment affected the expression of 11,772 annotated transcripts in female mosquitofish. Specifically, we found 5780 were repressed while 5992 were significantly induced. Gene ontology (GO) analysis showed that 53 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways and 158 GO terms were significantly over expressed. Genes showing the largest magnitude of expression changes were related to fin development, androgen biosynthesis, and lipid and fatty acid metabolisms, suggesting the involvement of these biological processes in response to NGT exposure in G. affinis. This first comprehensive study on the transcriptomic alterations by NGT in G. affinis not only provides valuable information on the development of molecular markers but also opens new avenues for studies on the molecular mechanisms of effects of NGT in particular and possibly other progestins in G. affinis.
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