Forms of phosphorus and silicon in the natural grain size surface sediments of the southern Bohai Sea

The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37 μmol/g to 1.57 μmol/g, accounting for 10.7% of the total phosphorus, others were the carbonate bound form, iron manganese oxide bound form and ion exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon’s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55 μmol/g to 8.94 μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12% of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.

Distributions of surficial sediments and its response to dynamic actions in the Xiamen Bay sea area, China

Sediment distribution is important for morphodynamic evolution and shoreline changes in coastal zones and estuaries. In the study, the data of 230 surface sediment samples collected from the Xiamen Bay sea area in September 2008 are used to investigate the spatial distribution and sediment transport pathway. The grain size distribution of surficial sediments in the Xiamen Bay area is shown distinctly in this study. In addition, the Grain Size Transport Analysis model is used for conveying trend analysis of the sediment in this area, particularly for determining the sediment movement trend. The results indicate that eight sediment types are present for samples, with clayey silt comprising the highest percentage in the study area at 65.22%. Moreover, in the different subareas, the characteristics of grain size parameters are obviously different owing to different sediment sources and hydrodynamic conditions. Furthermore, runoff, tides, and waves are the main forces dominating sediment dynamics on the seabed and tidal flats, and the sediment movement trend is closely related to hydrodynamic conditions.

Effects of Annealing Temperature on the Structural,Optical,and Electrical Properties of ZnO Thin Films Grown on n-Si<100>Substrates by the Sol–Gel Spin Coating Method

The effects of annealing temperature on the sol–gel-derived ZnO thin films deposited on n-Sh100 i substrates by sol–gel spin coating method have been studied in this paper.The structural,optical,and electrical properties of ZnO thin films annealed at 450,550,and 650 °C in the Ar gas atmosphere have been investigated in a systematic way.The XRD analysis shows a polycrystalline nature of the films at all three annealing temperatures.Further,the crystallite size is observed to be increased with the annealing temperature,whereas the positions of various peaks in the XRD spectra are found to be red-shifted with the temperature.The surface morphology studied through the scanning electron microscopy measurements shows a uniform distribution of ZnO nanoparticles over the entire Si substrates of enhanced grain sizes with the annealing temperature.Optical properties investigated by photoluminescence spectroscopy shows an optical band gap varying in the range of 3.28–3.15 eV as annealing temperature is increased from 450 to 650 °C,respectively.The fourpoint probe measurement shows a decrease in resistivity from 2：1 10 2to 8：1 10 4X cm with the increased temperature from 450 to 650 °C.The study could be useful for studying the sol–gel-derived ZnO thin film-based devices for various electronic,optoelectronic,and gas sensing applications.