[Nitrate Source Identification and Nitrification-denitrification at the Sediment-water Interface]

Identifying nitrate sources and its transformation mechanisms are important for nitrate pollution control in surface water. The columnar core sediment samples in West Lake were taken in different seasons. The transformation of nitrogen at the sediment-water interface was studied using nitrogen and oxygen isotopes, stable isotope analysis in R (SIAR) and acetylene inhibition method in the West Lake, Hangzhou. The results showed that the concentration gradient of both NO₃^-and NH₄⁺ existed at the sediment-water interface. NO₃^- concentrations decreased from bottom water to pore water and NO₃^- was accumulated in sediments. NH₄⁺ concentrations increased from bottom water to pore water and NH₄⁺ was released from sediments. Nitrate sources in bottom water where nitrification exited were sewage (manure), soil nitrogen, chemical fertilizer and precipitation. Sewage (manure) was the major nitrogen contributor (60.8%) in summer. Particularly high δ¹⁵ N values in pore water indicated that there was strong denitrification at the sediment-water interface in West Lake. The average nitrification rate and denitrification rate at the sediment-water interface were 2.85 mmol·(m²·d)^-1 and 23.51 μmol·(m²·d)^-1, respectively. The sediment-water interface played a role in nitrogen removal process in aquatic environment. Seasonal and spatial variations of nitrification rates and denitrification rates were found in this study. Temperature and dissolved oxygen were the main influential factors for the transformation of nitrogen at the sediment-water interface in West Lake.

First-Principles Studies on the Structural Stability of Spinel ZnCo2O4 as an Electrode Material for Lithium-ion Batteries

Systematic first principles calculations were performed for ZnCo₂O₄ to clarify its structural and electronic properties, and particularly the structural stability as an electrode material for lithium-ion batteries. For samples with low Li concentration, e.g., Li_nZnCo₂O₄ with n < 1, Li atoms take the center of oxygen octahedra and may diffuse rapidly. Structure distortions and volume expansions can be observed in Li_nZnCo₂O₄ with n > 1 and amorphous structures eventually prevail. The AIMD simulations for Li₉ZnCo₂O₄ suggest the formation of Li₂O, Co₃O₄ and LiZn local compounds or alloys. In particular, the formation of Zn-Co aggregations and the losing of ZnO pairs are identified as the possible reasons that are responsible to the Li capacity fading in ZnCo₂O₄ anodes.

[PBDEs Levels in House Dust and Human Exposure to PBDEs via Dust Ingestion in Hangzhou]

In order to evaluate the pollution degree of the dust in Hangzhou City, the indoor dust samples of 19 offices, families and students' dormitories were collected from August to March in 2013 at Hangzhou for evaluating the pollution level of polybrominated diphenyl ethers (PBDEs), to analyze concentrations of 14 PBDEs congeners and congener distribution as well as the possible influencing factors, and to estimate the PBDEs exposure levels of adults and children through the dust intake. The results showed that the average ∑₁₄PBDEs of office was 9.28×10² ng·g^-1, and the median was 1.03×10³ ng·g^-1; the average ∑₁₄PBDEs of family was 7.83×10² ng·g^-1, and the median was 9.11×10² ng·g^-1; the average ∑₁₄PBDEs of student dormitory was 4.07×10² ng·g^-1, and the median was 4.03×10² ng·g^-1. The pollution level of the office was higher than that of the living environment. BDE-209 was the largest monomer, and its contribution was 75.48%, followed by BDE-190, BDE-154 and BDE-71.PBDEs exposure levels of adults and children by dust intake were 13.12-32.63 ng·d^-1 and 32.40-54.54 ng·d^-1, respectively. Children's PBDEs exposure in the dust was higher than that of the adults, mainly because the average dust intake of children was higher than that of adults. The analysis showed that the PBDEs from indoor dust intake was a potential health hazard, and the biggest potential harm to children.

[Pollution status and characteristics of PBDEs in indoor air of Hangzhou]

Pollution Status and characteristics of PBDEs in offices were investigated in Hangzhou. As a result, the total concentration of PBDEs was 40.66-141.00 pg x m(-3), and the mean concentration was 93.22 pg x m(-3), being 1.87 and 5.01 times as high as those in homes and outdoor. In particle and gas phases, BDE-47 and BDE-99 were the most abundant congeners, which accounted for 33.29% and 31.99% of total PBDEs, respectively. Concentration of PBDEs in gas phase was 1.34 times as high as that in particle phase. BDE-28, BDE-47 and BDE-99 mainly existed in the gas phase, while BDE-153 and BDE-183 mainly existed in the particle phase.

[Research on anti-corrosion of Thiobacillus for the geopolymer solidification MSWI fly ash]

In order to discuss the anti-Thiobacillus corrosion performance of geopolymer solidification MSWI fly ash, the research simulated the Thiobacillus corrosion process by experiment, investigated the change of mass, compressive strength, leaching concentration. The results showed that geopolymer had a good anti-corrosion ability: weight loss within 1%, the compressive strength still reached 21.88 MPa after 28 days, the corrosion resistance coefficient was above 0.9. The maximum leaching concentration of Cr, Cu, Zn, Cd, Hg, Pb were 107.7 microg x L(-1), 22.71 microg x L(-1), 39.18 microg x L(-1), 0.56 microg x L(-1), 34.84 microg x L(-1) and 3.03 microg x L(-1), respectively. And the leaching concentration of geopolymer reduced with the immersion time, showed a good anti-Thiobacillus corrosion performance. Through the X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope spectra of geopolymer, we investigated the microstructure and mechanism of geopolymer anti-corrosion.