Ti-containing NPs in raw water and their removal with conventional treatments in four water treatment plants in Taiwan.

The ingestion of Ti-containing nanoparticles from drinking water has emerged as a concern in recent years. This study therefore aimed to characterize Ti-containing nanoparticles in water samples collected from four water treatment plants in Taiwan and to explore the challenges associated with measuring them at low levels using single particle-inductively coupled plasma mass spectrometry. Additionally, the study sought to identify the most effective processes for the removal of Ti-containing nanoparticles. For each water treatment plant, two water samples were collected from raw water, sedimentation effluent, filtration effluent, and finished water, respectively. Results revealed that Ti-containing nanoparticles in raw water, with levels at 8.69 µg/L and 296.8 × 103 particles/L, were removed by approximately 35% and 98%, respectively, in terms of mass concentration and particle number concentration, primarily through flocculation and sedimentation processes. The largest most frequent nanoparticle size in raw water (112.0 ± 2.8 nm) was effectively reduced to 62.0 ± 0.7 nm in finished water, while nanoparticles in the size range of 50-70 nm showed limited changes. Anthracite was identified as a necessary component in the filter beds to further improve removal efficiency at the filtration unit. Moreover, the most frequent sizes of Ti-containing nanoparticles were found to be influenced by salinity. Insights into the challenges associated with measuring low-level Ti-containing nanoparticles in aqueous samples provide valuable information for future research and management of water treatment processes, thereby safeguarding human health.

Urban Air Pollution in Taiwan before and after the Installation of a Mass Rapid Transit System.

Urbanization causes air pollution in metropolitan areas, coupled with meteorological factors that affect air quality. Although previous studies focused on the relationships of urbanization, air pollution, and climate change in Western countries, this study evaluated long-term variations of air quality and meteorological factors in Taiwanese metropolitan areas (Taipei area, Taichung City, and Kaohsiung City) and a rural area (Hualien County) between 1993 and 2012. The influence of a mass rapid transit (MRT) system on air quality was also evaluated. Air pollutant concentrations and meteorology data were collected from Taiwan Environmental Protection Administration (TEPA) air monitoring stations and Central Weather Bureau stations in the surveyed areas, respectively. Analyses indicate that levels of air pollution in metropolitan areas were greater than in the rural area. Kaohsiung City had the highest levels of O, SO, and particulate matter 2.5 or 10 µm in diameter (PM and PM). Clear downward trends for CO, NO, PM, PM, and especially SO concentrations were found in the surveyed areas, whereas O showed no decrease. Both O and PM concentrations showed similar bimodal seasonal distributions. Taiwan's air quality has improved significantly since 1993, indicating the effectiveness of promoting air pollution strategies and policies by the TEPA. Air pollution had an obvious improvement in Taipei area after the MRT system began operations in 1996. Because global climate may potentially affect urban air pollution in Taiwan, further study to clarify the mechanisms by which air pollution may affect human health and other biological effects is warranted.

Occurrence of nonylphenol and bisphenol A in household water pipes made of different materials.

We assessed the occurrence of nonylphenol (NP) and bisphenol A (BPA) in tap water supplied through polyvinyl chloride (PVC), stainless steel, and galvanized pipes. Water samples were collected from selected households in Taipei and Kaohsiung (Northern and Southern Taiwan, respectively) in different seasons to elucidate the effects of pipeline materials and ambient temperatures on NP and BPA concentrations in tap water. We detected higher concentrations of NP in tap water from households using PVC pipes (64-195 ng/L) than from those using stainless steel pipes (17-44 ng/L) and galvanized pipes (27-96 ng/L). To verify that water can absorb NP and BPA from PVC pipes, we sealed Milli-Q and tap water in PVC and stainless steel pipes to assess the potential release of NP and BPA from the pipes into the water. Both NP and BPA concentrations initially increased with contact time in the PVC pipes, and the concentration profiles during the retention appeared to be more strongly affected by ambient temperatures. Concentration variations in the stainless steel pipes were smaller than those in the PVC pipes.

Determination of perfluorinated chemicals in food and drinking water using high-flow solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry.

For this study, we developed methods of determining ten perfluorinated chemicals in drinking water, milk, fish, beef, and pig liver using high-flow automated solid-phase extraction (SPE) and ultra-high performance liquid chromatography/tandem mass spectrometry. The analytes were separated on a core-shell Kinetex C18 column. The mobile phase was composed of methanol and 10-mM N-methylmorpholine. Milk was digested with 0.5 N potassium hydroxide in Milli-Q water, and was extracted with an Atlantic HLB disk to perform automated SPE at a flow rate ranged from 70 to 86 mL/min. Drinking water was directly extracted by the SPE. Solid food samples were digested in alkaline methanol and their supernatants were diluted and also processed by SPE. The disks were washed with 40% methanol/60% water and then eluted with 0.1% ammonium hydroxide in methanol. Suppression of signal intensity of most analytes by matrixes was lower than 50%; it was generally lower in fish and drinking water but higher in liver. Most quantitative biases and relative standard deviations were lower than 15%. The limits of detection for most analytes were sub-nanograms per liter for drinking water and sub-nanograms per gram for solid food samples. This method greatly shortened the time and labor needed for digestion, SPE, and liquid chromatography. This method has been applied to analyze 14 types of food samples. Perfluorooctanoic acid was found to be the highest among the analytes (median at 3.2-64 ng/g wet weight), followed by perfluorodecanoic acid (0.7-25 ng/g) and perfluorododecanoic acid (0.6-15 ng/g).

Treatment of PPCPs and disinfection by-product formation in drinking water through advanced oxidation processes: Comparison of UV, UV/Chlorine, and UV/H2O2.

The presence of pharmaceutical and personal care products (PPCPs) in water is concerning because of their potential threat to ecosystems and human health. Studies have indicated that these emerging contaminants cannot be effectively removed through conventional water treatment. In this study, the efficacy of various treatments - chlorination, ultraviolet (UV), UV/Chlorine, and UV/H2O2 processes - in PPCP removal from water was compared. The effects of reaction time, oxidant concentration, pH, and water matrix and the generation of disinfection by-products (DBPs) were also assessed. The removal of PPCPs was discovered to be superior when the concentration of oxidants was higher. In addition, pH affected the reactivity of chlorine with some of the investigated chemicals. Chorine itself plays a minor role in the UV/Chlorine process because it serves as a reactant for the generation of free radicals rather than oxidants. Matrix had a weak effect on the removal of PPCPs in the various treatment processes (mostly within 10%). UV could not effectively remove acetylsalicylic acid, ibuprofen, benzophenone, oxybenzone, caffeine, N,N-diethyl-meta-toluamide, or most estrogens. When chlorine or hydrogen peroxide (H2O2) was used with UV, the efficiency of removal of all selected PPCPs was greatly improved (≥56.5% for UV/Chlorine and ≥27.6% for UV/H2O2) within 5 min. Although the PPCP removal efficiency of UV/Chlorine was higher than that of UV/H2O2, UV/H2O2 resulted in smaller amounts of DBP formation in the treated water. By contrast, UV/Chlorine resulted in higher concentrations of trihalomethanes (21.6%), haloacetonitriles (29.4%), and haloketones (147.2%).

Effects of temperature and microorganism densities on disinfection by-product formation.

This study investigated the role of microorganisms on the correlation between temperature changes and disinfection by-product formation in natural waters. Climate changes have resulted in an increase in the global surface temperature. Studies have revealed that increases in temperature may change the composition of dissolved organic matter (DOM), which may contain major disinfection by-product (DBP) precursors. This change in the DOM composition may affect DBP formation after conventional water treatment processes. Understanding the role of microorganisms in DOM composition as well as DBP formation and speciation is critical for controlling DBP formation. In this study, laboratory stimulatory experiments were conducted on water samples from various sources, at various temperatures, and with various microbial concentrations. The results revealed a decreasing trend of dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) at high temperature incubations irrespective of microbial concentrates. This result may be attributed to the fact that microorganism activities or concentrations in water increase at higher temperatures, which may result in higher DOC consumption and lower DBP formation. Water samples spiked with bacteria concentrates exhibited higher THMFP or HAAFP reduction than did samples without bacteria concentrates. A higher biomass in water may contribute to a higher consumption of DOC and consequently lower DBP formation potentials, especially at high incubation temperatures.

Biodegradation of MIB and geosmin with slow sand filters.

This study evaluated the biodegradation of MIB (2-methylisoborneol) and geosmin (trans-1,10-dimethyl-trans- 9-decalol) in simulated slow sand filtration (SSF) columns and in batch reactors. The results showed that both MIB and geosmin were biodegradable in the two systems. In batch experiments, the overall removals for MIB and geosmin were 50% and 78%, respectively, after 7 days of contact time. Volatilization loss plays an important role for geosmin in batch systems. Simulated SSF column studies also showed that more than 50% of geosmin and MIB were degraded by the microbial on the sand surface of a slow sand filter. With a filtration rate of 5 m/day, the simulated SSF degraded MIB from 48% to 69% and geosmin from 87% to 96%. The rapid biodegradation of MIB and geosmin in SSF column tests was attributed to the use of filter sands from the SSF unit in the Kinmen water treatment plant, where the microbial had been acclimated to both MIB and geosmin. The results also showed that more than 70% of the geosmin was removed in the top portion of the filter ( approximately 10 cm); while the removal of MIB occurred throughout the entire column depth. The results of this study demonstrated that slow flow through preacclimated sand was effective for control of MIB and geosmin in drinking water.

Occurrences of pharmaceuticals and personal care products in the drinking water of Taiwan and their removal in conventional water treatment processes.

Pharmaceuticals and personal care products (PPCPs) has been of concerns for their potential threats to ecosystems and human's health for decades. PPCPs have been detected in water environments worldwide and have been identified in water sources and finished water. To elucidate the potential exposure of PPCPs in drinking water, this study assessed the occurrences and treatment efficiencies of PPCPs in the drinking water of Taiwan. Raw and finished water samples collected from five main drinking water treatment plants (DWTPs) in February, June, and November 2018 were analyzed. Furthermore, laboratory-scale water treatment processes were conducted to evaluate the treatment efficiencies of these chemicals. Most of the water samples from the DWTPs had a low concentration (<30 ng/L) of PPCPs. Only samples from a DWTP was observed to have higher concentration of ibuprofen (55.6 ng/L), benzophenone (92.5 ng/L), caffeine (390.5 ng/L), and diethyltoluamide (DEET) (434.9 ng/L) in raw water than others. The results of laboratory simulations indicated that the pre-chlorination process was the key step responsible for the removal of PPCPs in conventional water treatment processes, which can remove most of the hormone treatment products, parabens, oxybenzone, and acetaminophen in water sources. However, the filtration process with anthracite as a medium could remove some of the parabens (approximately 11.9%-41.2%), hormones (approximately 18.2%-44.8%), suntan lotions (37.5%-68.8%), and naproxen (30.1%) from Milli-Q water. The removal efficiencies of the aforementioned chemicals were marginally lower in raw water. However, analgesics, caffeine, and DEET cannot be removed effectively through conventional drinking water treatment.

Assessing the potential effect of extreme weather on water quality and disinfection by-product formation using laboratory simulation.

Increased frequency and severity of extreme weather events (i.e., floods and droughts) combined with higher temperatures can threaten surface water quality and downstream drinking water production. This study characterized the effects of extreme weather events on dissolved organic matter (DOM) washout from watershed soils and the corresponding contribution to disinfection by-product (DBP) precursors under simulated weather conditions. A laboratory simulation was performed to assess the effects of temperature, drought, rainfall intensity, sea level rise, and acid deposition on the amount of DOM released from soil samples. DBP formation potentials (DBPFPs) were obtained to assess the effect of extreme weather events on DBP formation and drinking water quality. The results demonstrated that the dissolved organic carbon (DOC) and carbonaceous DBP levels increased with increasing temperature in a dry (drought) scenario. Regardless of the watershed from which a soil sample was obtained and the incubation temperature during rewetting or chlorination processes, the DOC and carbonaceous DBP levels also increased with increasing temperature. Brominated DBP formation was increased when bromide was present during the rewetting of soil, indicating the effect of sea level rise. When bromide was present during the chlorination of water for DBPFP tests, only the level of brominated DBPs increased. Acid deposition had various effects under different weather conditions. The results of heavy rainfall simulations suggested that water quality deteriorates at the beginning of an extreme rainfall event. Abundant DOM was washed out of soil, leading to a peak in the DBPFP level. The level of DOM in seepage water was less than that of the surface runoff water during rainfall. The situation was more severe when the rainfall came after a long drought and the drought-rewetting cycle effect occurred.

Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization for determining estrogenic chemicals in water by liquid chromatography tandem mass spectrometry with chemical derivatizations.

This study compared the sensitivities and matrix effects of four ionization modes and four reversed-phase liquid chromatographic (LC) systems on analyzing estrone (E1), 17beta-estradiol (E2), estriol (E3), 17alpha-ethinylestradiol (EE2), 4-nonylphenol (NP), 4-tert-octylphenol (OP), bisphenol A (BPA) and their derivatives of dansyl chloride or pentafluorobenzyl bromide (PFBBr) in water matrixes using a triple-quadrupole mass spectrometer with selected reaction monitoring (SRM). The four probes were electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI) and APCI/APPI; the four LC systems were ultra-performance liquid chromatography (UPLC) with or without post-column split, a mixed-mode column and two-dimensional LC (2D-LC). Dansylated compounds with ESI at UPLC condition had the most intense signals and less matrix effects of the various combinations of ionization and LC systems. The on-column limits of detection (LODs) of dansylated estrogens by SRM were 0.05-0.20 pg, and the LODs in sewage treatment plant effluent and in river water were 0.23-0.52 and 0.56-0.91 ng/L, respectively. The LODs using selected ion monitoring (SIM) reached low ng/L levels in real samples and measured concentrations were comparable with those of SRM.

Risk assessment of exposure to volatile organic compounds in groundwater in Taiwan.

The purpose of this study is to assess the risks from exposure to 14 volatile organic compounds (VOCs) in selected groundwater sites in Taiwan. The study employs the multimedia environment pollutant assessment system (MEPAS) model to calculate the specific non-cancer and cancer risks at an exposure level of 1 microg/L of each VOC for a variety of exposure pathways. The results show that the highest specific non-cancer risk is associated with water ingestion of vinyl chloride (VC) and that the highest specific cancer risk is associated with indoor breathing of VC. The three most important exposure pathways for risk assessment for both non-cancer and cancer risks are identified as water ingestion, dermal absorption when showering, and indoor breathing. Excess tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE), and VC are detected in the groundwater aquifers of one dump site and one factory. However, the study suggests that the pollutants in the contaminated groundwater aquifers do not travel extensively with groundwater flow and that the resulting VOC concentrations are below detectable levels for most of the sampled drinking-water treatment plants. Nevertheless, the non-cancer and cancer risks resulting from use of the contaminated groundwater are found to be hundred times higher than the general risk guidance values. To ensure safe groundwater utilisation, remediation initiatives for soil and groundwater are required. Finally, the study suggests that the current criteria for VOCs in drinking water might not be capable of ensuring public safety when groundwater is used as the primary water supply; more stringent quality criteria for drinking water are proposed for selected VOCs.

Determination of ten haloacetic acids in drinking water using high-performance and ultra-performance liquid chromatography-tandem mass spectrometry.

Haloacetic acids (HAAs) are a class of byproducts resulting from the reaction of chlorinated disinfectants with natural organic matter. These chemicals have been found in animal studies to possibly influence hepatic, reproductive, and developmental functions, and they may be mutagenic and carcinogenic. Because HAAs are hydrophilic and strongly acidic, it is a challenge to measure them at low levels. In this study, nine traditional HAAs and monoiodoacetic acid, an emerging disinfection byproduct, are analyzed in water directly. HAAs were separated on a BetaMax Acid column or a HILIC UPLC column, and they were detected by negative electrospray ionization-tandem mass spectrometry. Although the on-column limits of detection of HAAs were lower when using an HILIC UPLC column (0.08-2.73 microg/L) than when using a BetaMax Acid column (0.18 to 71.5 microg/L), to use an HILIC UPLC column, it was required to dissolve water samples in 90% acetonitrile before injection and result in sample dilution. BetaMax Acid column was found to be more suitable for the analysis of HAAs in drinking water because there was no need of sample preparation. Major species of HAAs, such as dichloroacetic acid and trichloroacetic acid, and other primary species (e.g., dibromoacetic acid, bromochloroacetic acid and bromodichloroacetic acid) can be detected using the BetaMax Acid column at concentrations higher than 1-3 microg/L.

Temperature dependence of characteristics of organic precursors, bromide, and disinfection byproduct formation.

This study characterized the potential effects of elevated water temperature on source water quality and corresponding disinfection byproduct (DBP) formation. Results of laboratory simulations showed that although DBP formation increased with temperature, both the concentrations of dissolved organic carbon (DOC) and DBP formation decreased when water was incubated at higher temperatures (35 °C) prior to chlorination, probably due to increased microbial activity leading to greater degradation of organic precursors that affects DBP formation. However, the effect of incubation temperature prior to chlorination on final DBP formation varies with the characteristics of source water. When bromide was present, the ratio of Br-DBPs increased. The concentrations of total trihalomethanes (THMs) and haloacetonitriles (HANs) also increased when levels of bromide increased. This trend was not substantial for total haloacetic acids (HAAs). The hydrophobic organic precursors of THMs and HANs can be effectively removed by coagulation and filtration processes, and the effects of higher incubation temperature may thus be compromised. However, no apparent changes were observed for HAAs. The effects of bromide may also be more apparent in HAA and HAN formation after coagulation and filtration treatments.

Bench-scale assessment of the formation and control of disinfection byproducts from human endogenous organic precursors in swimming pools.

In this study, a bench-scale system was utilized to assess the disinfection byproduct (DBP) formation from human endogenous organic matter. Perspiration and urine, constituting the main organic substances in swimming pools, were selected to represent the major human endogenous organics. Results revealed that the continuous input of body fluids into the reactor led to rapid accumulation of endogenous organic matter, which contributed to high concentrations of DBPs in the swimming pool. The increase in nonpurgeable organic carbon (NPDOC) concentration from the perspiration precursor was lower than that from urine during the operation. Moreover, the accumulation of swimmers' body fluids leads to increased DBP precursors, as well as increased chlorine demand and DBP formation in swimming pool water. The concentration of the trihalomethanes (THMs) and haloacetic acids (HAAs) consistently increased during the reaction. More THMs were generated in urine solution, whereas more HAAs were found in perspiration solution. To improve the water quality in swimming pools, ozonation, UV/Chlorine, and UV/H2O2 treatments were evaluated for their efficacy in reducing the DBP precursors. Results revealed that all of the three treatment processes can degrade the DBP precursors in perspiration and urine, eventually decreasing the DBP concentrations. However, only the UV/H2O2 treatment can decrease the formation of DBPs in perspiration and urine. In addition, the results revealed that UV/Chlorine and UV/H2O2 treatments should be operated for a sufficient contact time to prevent the increased production of DBP precursors in water at the early stage of the treatment.

Cancer risk assessment from trihalomethanes in drinking water.

This study intends to calculate the lifetime cancer risks resulting from intakes of trihalomethanes (THMs) in drinking water based on the presence of each THM species. The slope factors for each THM species are used, combined with exposure model and Monte Carlo simulations, to calculate the cancer risks with consideration of different exposure routes (oral ingestion, inhalation and dermal absorption). The results revealed that the highest risk comes from the inhalation exposure to chloroform during showers, which also dominates the total risk associated with chloroform exposure. For dichlorobromomethane and chlorodibromomethane, inhalation exposure also plays an important role for total risks; however, contribution from the oral consumption cannot be ignored for these two compounds. Bromoform contributes the least cancer risk among the four THM species, with a risk factor two orders of magnitude smaller than the other three THM species. For all of the four THM species, exposure from dermal absorption is not significant when compared with oral ingestion and inhalation exposures. This study also uses the THMs data collected from Taiwan to calculate the cancer risks associated with THM exposures in different areas of Taiwan. Due to the variations of the THMs compositions, it is observed that higher concentrations of total THMs do not necessarily lead to higher cancer risks. Areas with higher bromide concentration in raw water and often with higher total THM concentration may actually give lower cancer risk if the THMs formed shift to bromoform. However, this also leads to the violation of THM standards since bromoform has much higher molecular weight than chloroform. Based on the results of the cancer risks calculated from each THM species, the regulatory issue of the THMs was also discussed.

Determining estrogenic steroids in Taipei waters and removal in drinking water treatment using high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry.

River water and wastewater treatment plant (WWTP) effluents from metropolitan Taipei, Taiwan were tested for the presence of the pollutants estrone (E1), estriol (E3), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) using a new methodology that involves high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry. The method was also used to investigate the removal of the analytes by conventional drinking water treatment processes. Without adjusting the pH, we extracted 1-L samples with PolarPlus C18 Speedisks under a flow rate exceeding 100 mL/min, in which six samples could be done simultaneously using an extraction station. The adsorbent was washed with 40% methanol/60% water and then eluted by 50% methanol/50% dichloromethane. The eluate was concentrated until almost dry and was reconstituted by 20 microL of methanol. Quantitation was done by LC-MS/MS-negative electrospray ionization in the selected reaction monitoring mode with isotope-dilution techniques. The mobile phase was 10 mM N-methylmorpholine aqueous solution/acetonitrile with gradient elution. Mean recoveries of spiked Milli-Q water were 65-79% and precisions were within 2-20% of the tested concentrations (5.0-200 ng/L). The method was validated with spiked upstream river water; precisions were most within 10% of the tested concentrations (10-100 ng/L) with most RSDs<10%. LODs of the environmental matrixes were 0.78-7.65 ng/L. A pre-filtration step before solid-phase extraction may significantly influence the measurement of E1 and EE2 concentrations; disk overloading by water matrix may also impact analyte recoveries along with ion suppression. In the Taipei water study, the four steroid estrogens were detected in river samples (ca. 15 ng/L for E2 and EE2 and 35-45 ng/L for E1 and E3). Average levels of 19-26 ng/L for E1, E2, and EE2 were detected in most wastewater effluents, while only a single effluent sample contained E3. The higher level in the river was likely caused by the discharge of untreated human and farming waste into the water. In the drinking water treatment simulations, coagulation removed 20-50% of the estrogens. An increased dose of aluminum sulfate did not improve the performance. Despite the reactive phenolic moiety in the analytes, the steroids were decreased only 20-44% of the initial concentrations in pre- or post-chlorination. Rapid filtration, with crushed anthracite playing a major role, took out more than 84% of the estrogens. Except for E3, the whole procedure successfully removed most of the estrogens even if the initial concentration reached levels as high as 500 ng/L.

Characterization of titanium dioxide nanoparticle removal in simulated drinking water treatment processes.

This study characterized the fate of nano-TiO2 in both powder (TiO2(P)) and suspension (TiO2(S)) forms in simulated drinking water treatments. Nano-TiO2 solutions of 0.1, 1.0, and 10mg/L were prepared with deionized water and raw waters from the Changxing and Fengshan Water Treatment Plants in Taiwan to assess the effects of water matrices on nano-TiO2 behavior during water treatment. After the laboratory simulated water treatment, including pre-chlorination, coagulation, sedimentation, filtration and post-chlorination, the residual Ti concentration ranged from 2.7 to 47.4% in different treatment units and overall removal efficiency was between 52.6% and 97.3% in all cases except for nano-TiO2 at concentration of 0.1mg/L. Overall removal efficiency for the TiO2 at 10mg/L concentration ranged from 9.3 to 53.5%. Sedimentation (after coagulation) and filtration were the most important processes for removing nano-TiO2 due in part to particle agglomeration, which was confirmed by size distribution and zeta potential measurements. The size of nano-TiO2 increased from 21-36nm to 4490nm in the supernatant after sedimentation, and subsequent filtration treatment further removed all agglomerates at size >1µm. Zeta potential revealed interactions between nano-TiO2 particles and anionic functional groups or negatively-charged natural organic matters, leading to a decrease in surface charge. After sedimentation and filtration, the zeta potential of supernatants and filtrates were close to zero, meaning the absence of nanoparticles. The highest Ti removal after sedimentation occurred in Fengshan raw water due to higher ionic strength and coagulant dosage applied. On the other hand, the surfactant additives in TiO2(S) promoted dispersion of nano-TiO2 particles, which in turn led to lower particle removal. SEM images of nanoparticles after chlorination or coagulation revealed the coverage of nano-TiO2 particles by viscous substances and formation of colloidal structures.

Light-emitting-diode induced retinal damage and its wavelength dependency in vivo.

AIM: To examine light-emitting-diode (LED)-induced retinal neuronal cell damage and its wavelength-driven pathogenic mechanisms. METHODS: Sprague-Dawley rats were exposed to blue LEDs (460 nm), green LEDs (530 nm), and red LEDs (620 nm). Electroretinography (ERG), Hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunohistochemical (IHC) staining, Western blotting (WB) and the detection of superoxide anion (O2-·), hydrogen peroxide (H2O2), total iron, and ferric (Fe3+) levels were applied. RESULTS: ERG results showed the blue LED group induced more functional damage than that of green or red LED groups. H&E staining, TUNEL, IHC, and TEM revealed apoptosis and necrosis of photoreceptors and RPE, which indicated blue LED also induced more photochemical injury. Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and iron-overload were associated with retinal injury. WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency. CONCLUSION: The study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.

Urban air pollution and meteorological factors affect emergency department visits of elderly patients with chronic obstructive pulmonary disease in Taiwan.

Both air pollution and meteorological factors in metropolitan areas increased emergency department (ED) visits from people with chronic obstructive pulmonary disease (COPD). Few studies investigated the associations between air pollution, meteorological factors, and COPD-related health disorders in Asian countries. This study aimed to investigate the relationship between the environmental factors and COPD-associated ED visits of susceptible elderly population in the largest Taiwanese metropolitan area (Taipei area, including Taipei city and New Taipei city) between 2000 and 2013. Data of air pollutant concentrations (PM10, PM2.5, O3, SO2, NO2 and CO), meteorological factors (daily temperature, relative humidity and air pressure), and daily COPD-associated ED visits were collected from Taiwan Environmental Protection Administration air monitoring stations, Central Weather Bureau stations, and the Taiwan National Health Insurance database in Taipei area. We used a case-crossover study design and conditional logistic regression models with odds ratios (ORs), and 95% confidence intervals (CIs) for evaluating the associations between the environmental factors and COPD-associated ED visits. Analyses showed that PM2.5, O3, and SO2 had significantly greater lag effects (the lag was 4 days for PM2.5, and 5 days for O3 and SO2) on COPD-associated ED visits of the elderly population (65-79 years old). In warmer days, a significantly greater effect on elderly COPD-associated ED visits was estimated for PM2.5 with coexistence of O3. Additionally, either O3 or SO2 combined with other air pollutants increased the risk of elderly COPD-associated ED visits in the days of high relative humidity and air pressure difference, respectively. This study showed that joint effect of urban air pollution and meteorological factors contributed to the COPD-associated ED visits of the susceptible elderly population in the largest metropolitan area in Taiwan. Government authorities should review existing air pollution policies, and strengthen health education propaganda to ensure the health of the susceptible elderly population.

Comparative study on DBPs formation profiles of intermediate organics from hydroxyl radicals oxidation of microbial cells.

This study assessed the characteristics of disinfection byproducts (DBPs) formation from intermediate organics during UV/H2O2 treatment of activated sludge and algae cells under various reaction conditions. The DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), haloketones (HKs) and haloacetonitriles (HANs) in UV/H2O2-treated and chlorinated water were measured. The results showed that both dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) increased during the initial stage of UV/H2O2 treatment due to the lysis of sludge and algae cells, which enhanced the formation of both C- and N-DBPs; however, both DOC and DON decreased after longer reaction times. During the UV/H2O2 treatments, THMs formation potential (THMFP) peaked earlier than did HAAs formation potential (HAAFP). This shows that the dissolved organics released from lysis of microbial cells in the early stages of oxidation favor the production of THMs over HAAs; however, HAAs precursors increased with the oxidation time. Chlorination with bromide increased the formation of THMs and HAAs but less HKs and HANs were produced. Comparisons of normalized DBP formation potential (DBPFP) of samples collected during UV/H2O2 treatments of four different types of organic matter showed that the highest DBPFP occurred in filtered treated wastewater effluent, followed by samples of activated sludge, filtered eutrophicated pond water, and samples of algae cells. With increasing oxidation time, the dominant DBP species shifted from THMs to HAAs in the samples of activated sludge and algae cells. The DBPFP tests also showed that more HAAs were formed in biologically treated wastewater effluent, while the eutrophicated source water produced more THMs.