Determination for the different combined-form inorganic carbon in marine sediments

Marine sediment is the important sources and sinks of carbon. The inorganic carbon(IC) in marine sediments plays an important role in carbon cycling. In order to understand IC function in carbon cycling, sequential extraction method based on IC combined chemical strength difference were established to get five phases: NaCl phase (step I), NH3 - H2O phase (step II), NaOH phase (step III), NH2OH . HCl phase (step IV) and HCl phase(step V). The best extraction conditions were obtained by a series of experiments. Extractants were added into plastic centrifuge tubes in Step I - M, the capped tube were placed on a shaker table to keep the solids suspended for two hours. The suspended solution was separated by centrifugal, the residues were washed with water. The two supernatant were combined and the CO, was finally determined by volumetric analysis. The residues were transferred into conical flask in step IV and V, and then the extractants were added. The produced CO2 was adsorbed by saturated Ba(OH)(2) solution, and determined by volumetric analysis. This method for IC has a good precision in the analysis sediment samples.

Numerical Analysis of Rainfall Infiltration in the Slope with a Fracture

With the finite volume method, a 2D numerical model for seepage in unsaturated soil has been established to study the rainfall infiltration in the fractured slope.The result shows that more rain may infiltrate into the slope due to existing fracture and then the pore pressure rises correspondingly. Very probably, it is one of the crucial factors accounting for slope failure. Furthermore a preliminary study has been conducted to investigate the influence of various fracture and rainfall factors such as the depth, width and location of a crack, surface condition, rainfall intensity and duration. Pore pressure and water volumetric content during the transient seepage are carefully examined to reveal the intrinsic mechanism.