Fine particulate matter (PM2.5) has a small particle size, which allows it to directly enter the respiratory mucosa and reach the alveoli and even the blood. Many countries are already aware of the adverse effects of PM2.5, and determination of the sources of PM2.5 is a critical step in reducing its concentration to protect public health. This study monitored PM2.5 in the summer (during the southwest monsoon season) of 2017. Three online monitoring systems were used to continuously collect hourly concentrations of key chemical components of PM2.5, including anions, cations, carbon, heavy metals, and precursor gases, for 24 h per day. The sum of the concentrations of each compound obtained from the online monitoring systems is similar to the actual PM2.5 concentration (98.75%). This result suggests that the on-line monitoring system of this study covers relatively complete chemical compounds. Positive matrix factorization (PMF) was adopted to explore and examine the proportion of each source that contributed to the total PM2.5 concentration. According to the source contribution analysis, 55% of PM2.5 can be attributed to local pollutant sources, and the remaining 45% can be attributed to pollutants emitted outside Taipei City. During the high-PM2.5-concentration (episode) period, the pollutant conversion rates were higher than usual due to the occurrence of vigorous photochemical reactions. Moreover, once pollutants are emitted by external stationary pollutant sources, they move with pollution air masses and undergo photochemical reactions, resulting in increases in the secondary pollutant concentrations of PM2.5. The vertical monitoring data indicate that there is a significant increase in PM2.5 concentration at high altitudes. High-altitude PM2.5 will descend to the ground and thereby affect the ground-level PM2.5 concentration.

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Taipei Feitsui Reservoir supplies drinking water to more than five million citizens in northern Taiwan. The Feitsui Reservoir Administration and Tea Research and Extension Station have implemented a new pollution control measure for the use of low-phosphorous (low-P) fertilizers to prevent eutrophication. In this study, we compared the quality of the soil, effluent and tea from two test fields. Low-P fertilizer was applied to one of the fields, and regular phosphorous fertilizer (regular-P) was applied to the other. The study period covered spring and winter seasons. The results showed that the investigated soil chemical properties were not influenced by either the low-P or regular-P fertilizers. The effluent quality was influenced by the precondition of the soil, which resulted in a larger average total phosphorous (TP) concentration in the low-P field. However, there was a decreasing trend in P concentration that amounted to approximately half of the average TP concentration in the regular-P field. The growth characteristics and yields were not significantly different between the two fields, but the taste and aroma of the tea from the low-P field was rated as superior to that of the regular-P field. OPEN ACCESSSustainability 2014, 6 6986

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