Yanyan Yin

Spatial distribution and risk assessment of heavy metals in sediments of Shuangtaizi estuary, China.

In order to evaluate the spatial distribution and potential ecological risk of Pb, Cu, Zn, Cd, and Hg, the surface sediments were collected from 18 sites in the Shuangtaizi estuary. The concentrations of Pb, Cu, Zn, Cd, and Hg were analyzed by atomic absorption spectrophotometry and atomic fluorescence spectrometry after digestion. The particle sizes of the sediments were analyzed using a laser diffraction particle size analyzer. The results show that the heavy metal contents in the sediments are observed in the following order: Zn (18.25-126.75mg/kg)>Pb (4.38-9.65mg/kg)>Cu (1.80-17.68mg/kg)>Cd (0.241-0.764mg/kg)>Hg (0.007-0.021mg/kg). In comparison with the concentrations of heavy metals in other regions, the concentrations of Pb, Cu, and Zn in the Shuangtaizi estuary are generally low, and the Cd concentrations are close to those reported in other regions. Both the potential ecological risk index and the geoaccumulation index reveal that the heavy metal pollution in Shuangtaizi estuary is mainly dominated by Cd.

Assessment of Heavy Metal Contamination in the Sediments of the Shuangtaizi Estuary Using Multivariate Statistical Techniques

ABSTRACT In order to assess heavy metal pollution of sediment samples collected from Shuangtaizi estuary, contamination factor (CF) and multivariate statistical analyses, including principal component analysis (PCA), cluster analysis (CA) and correlation analysis, are carried out in this paper. CF confirms that Pb, Cu and Hg concentrations are very low and all fall within the range of background, while Zn and Cd demonstrate moderate contamination (in A10, A13, A15, A16 and A17 sites) and very high contamination (in A10, A13, A15 and A17 sites), respectively. The PCA indicates that four significant principal components (PCs) are extracted, explaining 88.959% of total variance, which suggests that Pb, Cu and Zn are mainly associated with organic carbon (OC). The result from CA is consistent with that obtained from PCA, classifying that the heavy metals in two clusters derive from different sources. Correlation analysis supports the conclusions from PCA and CA, elucidating the relationships between heavy metals and particle sizes of the sediments.

Morphologically controlled synthesis of porous Mn2O3 microspheres and their catalytic applications on the degradation of methylene blue

AbstractPorous Mn2O3 microspheres are controllably synthesized by selectively etching MnCO3 precursor with HCl solution. Morphologies and microstructures of Mn2O3 microspheres are analyzed by SEM, TEM, XRD, and N2 sorption technique. The catalytic performances of Mn2O3 microspheres for the degradation of methylene blue (MB) are investigated, and the reaction kinetics of MB degradation is also studied. The results show it is feasible to control the morphologies of Mn2O3 microspheres by adjusting the concentration of HCl solution, and the well-developed porous Mn2O3 microspheres demonstrate good potential on MB degradation. The degradation reactions follow the pseudo-first-order kinetic model, and the degradation capabilities for MB are great dependent on BET surface areas and pore volumes of Mn2O3 microspheres.

Preparation and Gas Sensing Properties of Hierarchical Flower-Shaped Bi2WO6

Hierarchical flower-shaped Bi2WO6 was obtained by a simple hydrothermal method. Morphology and structure of the Bi2WO6 were characterised by single electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and N2 adsorption techniques. Gas sensing properties of the Bi2WO6 sensor were investigated by a static gas-sensing system. The results show the as-synthesised flower-shaped product is pure orthorhombic Bi2WO6, which is composed of nanosheets with ~10–20 nm in thickness and hundreds of nanometres in planar size. At this optimal operating temperature of 300°C, the Bi2WO6 sensor exhibits ultra-fast response (1-2 s) and fast recovery time (6–12 s) towards ethanol detection, and high selectivity to other gases such as methanol, benzene, dichloromethane, and hexane.