Measurement methods for evaluation and monitoring of indoor air pollution by formaldehyde (HCHO) and volatile organic compounds (VOCs) were described. HCHO evaluated with a guideline of 0.08ppm for 30min is usually determined with DNPH/high performance liquid chromatography, and VOCs by porous polymer beads collection/thermal desorption/gas chromatography. The pollutants in indoor air are collected on adsorbents by active sampling with a pump or passive sampling with diffusion. Principle and characteristics of onsite-monitor and simple method such as detector tube and paper respectively were described. The concentration values are affected with ventilation and elapse time after close in sampling. Methods for measurement of emission rate of HCHO and VOCs from building materials with chambers were also described.
By this time, environmental problems had been put firmly on political agenda. A great deal of research is still being carried out on environmental analysis. Dioxins are global pollutants, so rigid regulation had been performed by environmental agency. Dioxin analysis should be done by ultra trace analytical techniques. Dioxin analysis requires very complicated and long term procedures. Dioxin analysis is very useful to environmental integrity and control of dioxin contents.
Atomic absorption spectrometry (AAS), Inductively coupled plasma atomic emission spectrometry (ICP-AES) and Inductively coupled plasma mass spectrometry (ICP-MS) have been used to determine heavy metals in environmental samples. After the pretreatment of sample such as the digestion with acids, the solvent extraction, and the coprecipitation with iron hydroxide, heavy metals are measured by the AAS, ICP-AES, ICP-MS. Measurement principle and characteristics of each method are commented in this paper. Pretreatment of sample is also commented.
The persistent organic pollutants and some other chemical compounds in the environment which exhibit endocrine modulating effects has attracted much attention recently. These chemicals are referred to as endocrine disruptors or environmental hormones, and a variety of chemicals including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins, pesticides such as DDT, plastic additives such as bisphenol A, detergent additives such as alkylphenols are listed as the endocrine disruptors. It has also been shown that specific hydroxylated PCBs interact with the estrogen hormone and thyroid hormone systems. Several hydroxylated PCBs metabolites, which structure is resemble to that of thyroid hormone, thyroxine (T4), are determined in human blood. These observations indicate the significance of hydroxylated PCBs metabolites as potential endocrine disruptors in human. This paper reviews the metabolism of PCBs, endocrine-disrupting effects of hydroxylated PCBs based on interactions with estrogen hormone metabolism, thyroid hormone metabolism and the chemical analysis of phenolic organohalogen compounds such as hydroxylated PCBs. Measurement of estrogenic activities of hydroxylated PCBs by bioassay (yeast two-hybrid assay) is also presented.
Pitting behavior of type 304 stainless steel has been investigated in LiBr and NaCl solutions containing nitrate ion through measurements of pitting potential (E′pit) as a function of temperature, and pitting temperature (T′pit) as a function of potential. In the absence of nitrate ion, E′pit in NaCl solution became less noble with temperature while E′pit in LiBr solution was less sensitive to temperature. A similar relation was found between T′pit and potential. The inhibitive effect of nitrate ion against pitting was only apparent below 298K in LiBr solution and below 323K in NaCl solution. Above these temperatures, E′pit was not improved significantly by the addition of nitrate. Nitrate ion inhibited pitting effectively when E′pit ranged over ca. 400mV (vs. Ag/AgCl/2mol kg-1 KCl). Actually, T′pit decreased with potential up to ca. 400mV and then turned to increase in NaCl+NaNO3 solution. In LiBr+LiNO3 solution, T′pit decreased with potential up to ca. 600mV and increased slightly above it. It was estimated that LiBr solution became extremely aggressive above ca. 400mV canceling out the inhibitive action of nitrate at nobler potentials.
A CoNiCrAlY/YSZ (ZrO2-8mol%Y2O3) film prepared by low-pressure and air plasma spraying was oxidized in air at 1173 and 1273K for up to 3240ks. Thickness and concentration profiles across oxide scales and Al depleted zone with disappearing β-NiAl phase were measured for both the CoNiCrAlY/YSZ interface and the CoNiCrAlY surface by using an electron probe micro-analysis. The oxide layer at the interface was Al-rich oxide containing Co, Ni, and Cr in addition to Y, while the oxide at the surface consisted of pure Al2O3, except for that it contains Y at the alloy side. The former grew three times thicker than the latter. A ratio of thickness between the Al depleted zone and the oxide layer ranged from 3 at 1173K to 4 at 1273K. Concentration profiles of each element measured across the Al depleted zone were almost flat, except for that at the interface oxidized at 1173K, where Al and Ni concentrations decreased towards the Al-rich oxide layer, whereas Co and Cr concentrations increased.
The dissolution behavior and mechanism of chromium carbide precipitation near the surface of Fe-Cr-C alloy were investigated by electron probe microanalysis. There was a 100μm of chromium carbide dissolution layer near the surface of SCH2 heat resistant steel exposed at 1273K for 345.6ks in air. The chromium carbide dissolution layer was also identified on the specimen exposed at 1473K for 345.6ks in air and at 1273K for 14.4ks in H2. The result of EPMA analysis showed that not only chromium but also carbon were depleted on chromium carbide dissolution layer. The chromium content that was detected at the chromium carbide dissolution layer/chromium carbide layer interface was higher than the critical chromium content to form chromium carbide on Fe-Cr-C phase diagram. The Fe-Cr-C phase diagram shows that critical chromium content to form the Cr carbide increases with the reduction of carbon. This shows that the chromium content that was detected at the chromium carbide dissolution layer/chromium carbide layer interface was increased by decarburization from the surface during the exposure. It was concluded that the chromium carbide dissolution layer formed at 1273K was formed both in air and H2 by the same mechanism as that at higher temperature up to 1473K.