Evaluation of sediment capping effectiveness in Hyeongsan River for in-situ management of total mercury and methylmercury contamination

Journal of Soils and Sediments - In this study, the effectiveness of in situ sediment capping was investigated as a remediation option for total mercury (THg) and methylmercury (MeHg) in the...     

Synthesis and Biological Evaluation of Carbocyclic Analogues of Pachastrissamine

A series of carbocyclic analogues of naturally-occurring marine sphingolipid pachastrissamine were prepared and biologically evaluated. The analogues were efficiently synthesized via a tandem enyne/diene-ene metathesis reaction as a key step. We found that the analogue 4b exhibited comparable cytotoxicity and more potent inhibitory activity against sphingosine kinases, compared to pachastrissamine. Molecular modeling studies were conducted to provide more detailed insight into the binding mode of 4b in sphingosine kinase. In our docking model, pachastrissamine and 4b were able to effectively bind to the binding pocket of sphingosine kinase 1 as co-crystalized sphingosine. However, 4b showed a hydrophobic interaction with Phe192, which suggests that it contributes to its increased inhibitory activity against sphingosine kinase 1.     

Modeling the Effect of pH and Salinity on Biogeochemical Reactions and Metal Behavior in Sediment

A mathematical model is developed to investigate the effect of pH and salinity fluctuation on biogeochemical reactions and metals' behavior in sediments. The model includes one-dimensional vertical advective and diffusive transport of species, serial reductions of electron acceptors, and precipitation/dissolution of species, acid–base chemistry, and metal sorption to sediments. The model was tested using data obtained from laboratory microcosm experiments which exposed metal (Cd, Zn) contaminated sediment to alternating fresh and salty overlying water. The model successfully reproduces the contrasting metal's release behavior and the vertical profiles of pH, Cl^?, SO₄ ^2?, Mn and Fe in porewater and the acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments. The model showed that FeOOH_(s) was the dominant sorption phase controlling the solubility of the metals at the surficial sediments while AVS controlled the solubility of the metals in anoxic sediments. The model also showed that the release of the metals to overlying water was controlled by the oxidation of metal sulfides in a very thin layer of oxic sediments (2–3 mm). The proposed model can be useful in managing metal contaminated sediments where pH and salinity are fluctuating by assessing the underlying biogeochemical processes and metals' behavior.