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Microplastics are widespread in freshwaters, yet their interaction with navigational structures remains unclear. This study compared the distribution and characteristics of microplastics before and after navigation in Wabu Lake. Microplastic concentrations decreased significantly in both surface water and sediment due to navigation opened, from 13.7 ± 6.56 to 3.12 ± 1.8 p L-1 (p < 0.001) and from 568 ± 286 to 174 ± 60.2 p kg-1 (p < 0.001), respectively. Acrylates copolymer was frequently detected in surface water and sediment before navigation, whereas the dominant polymer after navigation was chlorinated polyisoprene in surface water and chlorinated polyethylene in sediment. The results showed that three-years dredging induced relatively severe microplastic pollution before navigation, however, these microplastics were apparently eliminated after navigation, as the distribution and characteristics of microplastics thoroughly varied. This study provides a valuable finding that microplastic transport process can be facilitated by water transfer project, which should be considered for preventing microplastic pollution.
RESUMO
BACKGROUND: In this study, we evaluated the effects of fructose-1,6-diphosphate (FDP) on high-energy phosphate metabolism during 18-hour hypothermic rabbit-heart preservation. METHODS: Under general anesthesia and artificial ventilation, hearts from 42 adult New Zealand white rabbits were harvested, flushed, and preserved in St. Thomas solution at 4(o)C for 18 hours. In the study group (n = 15), FDP (5 mmol/liter) was added to the St. Thomas solution, whereas in the control group (n = 17), fructose (5 mmol/liter) was added. Another 10 hearts did not undergo hypothermic storage, but were used as the normal group for high-energy phosphate concentration comparison. RESULTS: After 18 hours of hypothermic preservation, myocardial high-energy phosphate content decreased in both preservation groups. In the study group, left ventricular adenosine triphosphate (ATP) content was 33% of that in the normal hearts, but in the control group, ATP decreased to 14% of normal. Adenosine diphosphate (ADP) content, energy charge, and ATP-to-ADP ratio showed similar decreases. The high-energy phosphate profile (content in the atria and ventricles and the ratio of ATP to ADP to AMP) was maintained in the study group but not in the control group. High-energy phosphate metabolites such as inosine monophosphate (IMP), inosine, and hypoxanthine increased in both preservation groups, but the increase was more prominent in the control group. CONCLUSION: Adding FDP to St. Thomas solution attenuated the depletion of high-energy phosphate concentration in the preserved hearts. This difference was especially prominent in the left and right ventricles. The protective effect of FDP during hypothermic heart preservation deserves further study.