Identification of carbonates as additives in pressure-sensitive adhesive tape substrate with Fourier transform infrared spectroscopy (FTIR) and its application in three explosive cases.

Pressure-sensitive tape is often used to bind explosive devices. It can become important trace evidence in many cases. Three types of calcium carbonate (heavy, light, and active CaCO(3)), which were widely used as additives in pressure-sensitive tape substrate, were analyzed with Fourier transform infrared spectroscopy (FTIR) in this study. A Spectrum GX 2000 system with a diamond anvil cell and a deuterated triglycine sulfate detector was employed for IR observation. Background was subtracted for every measurement, and triplicate tests were performed. Differences in positions of main peaks and the corresponding functional groups were investigated. Heavy CaCO(3) could be identified from the two absorptions near 873 and 855/cm, while light CaCO(3) only has one peak near 873/cm because of the low content of aragonite. Active CaCO(3) could be identified from the absorptions in the 2800-2900/cm region because of the existence of organic compounds. Tiny but indicative changes in the 878-853/cm region were found in the spectra of CaCO(3) with different content of aragonite and calcite. CaCO(3) in pressure-sensitive tape, which cannot be differentiated by scanning electron microscope/energy dispersive X-ray spectrometer and thermal analysis, can be easily identified using FTIR. The findings were successfully applied to three specific explosive cases and would be helpful in finding the possible source of explosive devices in future cases.

Assessment of pesticide pollution in suburban soil in south Shenyang, China.

In this study, 35 representative farmland soil samples from suburban areas in south Shenyang, the capital city in Liaoning province, China, were collected to evaluate the pollution of 114 pesticides. Surface soil samples were air-dried and sieved. Ultrasonic extraction was used for pesticides preparation prior to analysis with gas chromatography-mass spectrometry. The total concentrations of tested pesticides in the area ranged in 0-51.32 ng/g and the average of concentrations was 6.86 ng/g. Six pesticides, including butachlor(with detect frequency 71.4%), p,p'-DDE (88.6%), p,p'-DDT (77.1%), o,p'-DDD (82.9%), hexachlorobenzene (88.6%) and δ-HCB (77.1%), were detected most frequently. It indicated that DDTs (N.D.-40.25 ng/g) and HCHs (N.D.-42.79 ng/g) were the predominant pesticide pollutants in soil because of their long term persistence. On the contrary, most of organophosphorus pesticides, pyrethroids and carbamates were not detected. Spatial variation of six pesticides with high detection frequency (>70%) in soil was illustrated. Pollution levels, characteristics and the possible sources were also discussed. The data were helpful to figure out the pollution of the pesticides and could be further used to evaluate the health risk associated with food safety.

Levels, spatial distribution and possible sources of heavy metals contamination of suburban soils in Tianjin, China.

Representative soil samples (n = 86) of suburban areas in Tianjin (Xiqing, Dongli, Jinnan, Beichen) were evaluated for heavy metals. The results showed that the average concentration of Cr, Cu, Zn, As, Cd, Pb and Hg in soil of Tianjin suburban was 101.0, 67.0, 100.6, 9.5, 0.49, 52.5 and 0.97 mg/kg, respectively. Pollution of Cr and Zn were minimal compared to the other elements while concentrations of Cd and Hg were higher than their natural background values. Spatial variations of Cd, Hg, Pb and Cu in soil were illustrated; Pollution status and comparison in the four districts were also investigated. Higher concentrations of Hg and Cd were found in soils of Beichen than others indicating that Beichen was suffering from metal contamination. Principal Component Analysis in combination with local specific environment suggested that heavy metal contamination had different origination. Wastewater and sludge irrigation, air deposition might be the most important sources. These results, especially the spatial distribution of pollutants, would be helpful to develop proper management strategies and decrease source pollution by various remediation practices in Tianjin, China.

Assessment of 20 organochlorine pesticides (OCPs) pollution in suburban soil in Tianjin, China.

Soil contamination with organochlorine pesticides has aroused worldwide concerns considering their high toxicities and long-term persistence. In this study, 87 representative soil samples from suburban areas (Xiqing, Dongli, Jinnan, Beichen) of Tianjin, the third biggest city in China, were collected to evaluate the pollution of 20 organochlorine pesticides. Surface soil samples were air-dried and sieved. Ultrasonic extraction was used for organochlorine pesticides preparation prior to analysis with gas chromatography-mass spectrometry. It was revealed that p,p'-DDE, p,p'-DDD, o,p'-DDT, o,p'-DDD, hexachlorobenzene, dicofol and beta-HCH were seven pesticides detected most frequently. DDTs, HCHs and hexachlorobenzene were the predominant pesticide pollutants in soil. Spatial variation of these organochlorine pesticides in soil was illustrated; Pollution levels, characteristics and possible sources were also investigated. Most of other 13 kinds of pesticides were detected and the frequencies of detection were calculated to reveal the pollution status, which ranged from 0.0% (aldrin, dieldrin and endrin) to 34.5% (p,p'-DDT). These data were helpful to figure out the pollution of organochlorine pesticides and could be further used to evaluate the health risk associated with soil pollution.