Polybrominated diphenyl ethers (PBDEs) in dust in typical indoor public places in Hangzhou: Levels and an assessment of human exposure.

Polybrominated diphenyl ethers (PBDEs) are organic pollutants (POPs) with the characteristics of environmental persistence, long-distance transmission in nature, biological accumulation and toxic effects on human health. To investigate the level of contamination due to PBDEs in typical indoor public places in Hangzhou, dust samples were collected from ten supermarkets, three electronic markets and five different areas throughout one commodity market. Based on sample pretreatment and GC-ECD instrumental analysis, the contamination characteristics, sources and the influencing factors of 14 PBDE congeners were analyzed. The results revealed that the mean of ∑14PBDEs in dust in the supermarkets and electronic markets was 546.13 ng/g and 1140.05 ng/g, respectively, while in the commodity market the mean was 1005.42 ng/g and varied in the five different areas as follows: shoe areas (1367.22 ng/g) > parking lot (1001.05 ng/g) > waiting halls (970.31 ng/g) > packet areas (933.23 ng/g) > curtain areas (755.28 ng/g). The high levels of PBDE were attributed to the quantity of electrical appliances in the supermarkets (r = 0.708*, p < 0.05) and the electronic markets (r = 0.799**, p < 0.05) through Spearman correlation coefficient analysis. BDE-209 was the dominant congener, accounting for 53.72% in supermarkets and 64.25% in electronic markets. The calculated inhalation exposure revealed that the exposure level of PBDEs varied in supermarkets, electronic markets and commodity markets, with values of 0.476 ng/day/kg, 0.993 ng/day/kg and 0.876 ng/day/kg, respectively. Moreover, BDE-209's contribution to the total intake of PBDEs was the highest, with a value of 0.072-0.970 ng/day/kg, while the value of BDE-183 was the lowest, with a value of 0-0.020 ng/day/kg. The exposure level of PBDEs in the studied indoor public places was lower than the reference dose of EPA.

[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.

[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.

[Immobilization of heavy metal Pb2+ with geopolymer].

A series of geopolymers were synthesized by mixing metakaolinite, water glass, sodium hydroxide and water, and the lead ion solidification experiments were performed with the geopolymer. Then, the immobilization efficiency was characterized by monitoring the leaching concentration and compressive strength of solidified products. Additionally, the structure and properties of the solidified products were studied by X-ray diffraction (XRD), scan electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Furthermore, based on the analysis of immobilization efficiency, microstructure and mineral structure, the difference between geopolymer and cement on the performance of immobilizing heavy metals was discussed. The results of lead ion immobilization experiments showed that over 99.7% of heavy metal was captured by the geopolymer as the doping concentration of lead ion was less than 3%. Meanwhile, the compressive strength of the solidified product ranged from 40 MPa to 50 MPa. Furthermore, by using the same Pb2+ concentration, the geopolymer showed higher compressive strength and lower leaching concentration compared to the cement. Because lead ion participated in constitution of structure of geopolymer, or Pb2+ was adsorbed by the aluminium ions on the geopolymeric skeleton and held in geopolymer. However, cement mainly solidified lead ion by physical encapsulation and adsorption mechanism. Therefore, both from the compressive strength and leaching concentration and from the microstructure characterization as well as the mechanism of the geopolymerization reaction, the geopolymer has more advantages in immobilizing Pb2+ than the cement.