[Comparative Analysis of NOx Emission Characteristics of Non-Ultra-Low- and Ultra-Low-Emission Coal-Fired Power Units During the Start-Up Process].

Based on the NOx emission information of 671 coal-fired power units, the NOx emission characteristics of non-ultra-low-emission (non-ULE) and ultra-low-emission (ULE) coal-fired power units during the start-up process were compared and analyzed. The results showed that in the start-up stage of non-ULE units, the exceeding standard rate (ESR) of NOx emission concentration was 81.53%, the average exceeding standard hours (ESHs) was 2.64 h, and the average maximum emission hourly mean concentration (MEHC) was 284.06 mg·m-3. The NOx ESR of ULE units was 79.86%, the average ESHs was 2.52 h, and the average MEHC was 231.61 mg·m-3. There was no significant difference in the ESR and the average ESHs between non-ULE and ULE units, but the difference in the average MEHC was significant. There was no significant difference in the ESR, average ESHs, and average MEHC between different grades of non-ULE units, except that the average MEHC of 300 MW units was significantly lower than that of 200 MW units. There was statistical difference in the ESR, average ESHs, and average MEHC among different grades of ULE units, and 600 MW units performed best in the ESHs control, whereas 1000 MW units performed best in the emission concentration control.

[Health risk assessment of heavy metals in drinking water based on field measurement of exposure factors of Chinese people].

This study was carried out in Biyang County, located in the junction of Yangtze river and Huaihe river. Drinking water samples of 20 sites in urban and rural areas in this county were collected to measure 14 heavy metals by ICP/MS. About 2 500 subjects with different age and sex were selected to measure exposure factors. Time-activity of drinking water by ingestion and dermal contact of each individual subject during the last three days were kept in dairy in detail by questionnaires. Intake of drinking water from direct and indirect consumption of water and time duration of dermal contact to water in each individual subject were kept in record based on real time measurements. Human health risks were assessed and sensitivity of exposure factors and uncertainty of risks were also analyzed. The results showed that the average drinking water intake rate of male and female are 2276 mL/d, 2265 mL/d in urban adults and 2464 mL/d, 2170 mL/d in rural adults respectively. Body surface area of male and female are 1.806 m2, 1.641 m2 in urban adults and 1.747 m2, 1.617 m2 in rural adults respectively. The contents of 14 heavy metals in this study area are all below the national drinking water standards. Cancer risks from exposure to As are ranged from 2.5 x 10(-6) to 5.2 x 10(-6) through ingestion and 1.1 x 10(-7) to 2.3 x 10(-7) through dermal exposure. Non-cancer risks are ranged from 2.1 x 10(-7) to 1.7 x 10(-6) through ingestion and 1.0 x 10(-8) to 6.0 x 10(-8) through dermal exposure. Non-cancer risks in rural population are 2.1 times to 5.6 times to the risks in urban populations. However all the risks are below the acceptable level. The sensitivity of various exposure factors including drinking water intake rate, dermal exposure time and body surface area are 71.5%. This indicates that exposure factors play a very important role in health risk assessment. Health risks in this research based on real measurement of exposure factors are about 0.94 time to 6.33 times higher than the risks based on the references of the data from the exposure factors handbooks in other countries. This study showed that the accuracy of health risk assessment could be improved a lot by the real measurements of exposure factors. Attentions should be attached to exposure factor investigation to decrease uncertainty of health risk assessment.