Disinfection by-product dynamics in a chlorinated, indoor swimming pool under conditions of heavy use: national swimming competition

Anecdotal evidence suggests that water quality in chlorinated, indoor pools deteriorates under conditions of heavy use. However, data to define these dynamics have not been reported. To address this issue, a study was performed in which water chemistry was monitored in a chlorinated, indoor pool before and during a national swimming competition, a period of heavy, intense use. NCl₃ concentration was observed to double after the first day, and increased by a factor of 3-4 over the 4 days of competition. CNCHCl₂ and CH₃NCl₂ concentrations both increased by a factor of 2-3 during the course of the meet, while CHCl₃ concentration showed only a modest increase during this same period. Diurnal patterns of NCl₃, CH₃NCl₂ and CHCl₃ concentrations were observed, and these patterns appeared to depend on the Henry’s law constant of the compound.Urea concentration showed a diurnal pattern, superimposed on a trend of steady increase during each day of the competition; however, the diurnal pattern of urea behavior could not be explained by reactions with chlorine, as the urea-free chlorine reaction is relatively slow. It is more likely that the overnight decrease in urea concentration was attributable to mixing of surface water with water in the deeper parts of the pool. The findings of this study provide an indication of the changes in pool water chemistry that take place in a chlorinated, indoor pool under heavy use conditions.     

Effects of UV 254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools

Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precursors in swimming pools.Creatinine, L-arginine, L-histidine, glycine, and urea, which comprise the majority of the organic-N in human sweat and urine, were selected as precursors for use in conducting batch experiments to examine the time-course behavior of several DBPs and residual chlorine, with and without UV₂₅₄ irradiation. In addition, water samples from two natatoria were subjected to monochromatic UV irradiation at wavelengths of 222 nm and 254 nm to evaluate changes of liquid-phase chemistry. UV₂₅₄ irradiation promoted formation and/or decay of several chlorinated N-DBPs and also increased the rate of free chlorine consumption. UV exposure resulted in loss of inorganic chloramines (e.g., NCl₃) from solution. Dichloromethylamine (CH₃NCl₂) formation from creatinine was promoted by UV exposure, when free chlorine was present in solution; however, when free chlorine was depleted, CH₃NCl₂ photodecay was observed. Dichoroacetonitrile (CNCHCl₂) formation (from L-histidine and L-arginine) was promoted by UV₂₅₄ irradiation, as long as free chlorine was present in solution. Likewise, UV exposure was observed to amplify cyanogen chloride (CNCl) formation from chlorination of L-histidine, L-arginine, and glycine, up to the point of free chlorine depletion. The results from experiments involving UV irradiation of chlorinated swimming pool water were qualitatively consistent with the results of model experiments involving UV/chlorination of precursors in terms of the behavior of residual chlorine and DBPs measured in this study.The results indicate that UV₂₅₄ irradiation promotes several reactions that are involved in the formation and/or destruction of chlorinated N-DBPs in pool settings. Enhancement of DBP formation was consistent with a mechanism whereby a rate-limiting step in DBP formation was promoted by UV exposure. Promotion of these reactions also resulted in increases of free chlorine consumption rates.     

Dynamic real‐time monitoring of chloroform in an indoor swimming pool air using open‐path Fourier transform infrared spectroscopy

This study used open‐path Fourier transform infrared (OP‐FTIR) spectroscopy to continuously assess the variation in chloroform concentrations in the air of an indoor swimming pool. Variables affecting the concentrations of chloroform in air were also monitored. The results showed that chloroform concentrations in air varied significantly during the time of operation of the swimming pool and that there were two peaks in chloroform concentration during the time of operation of the pool. The highest concentration was at 17:30, which is coincident with the time with the highest number of swimmers in the pool in a day. The swimmer load was one of the most important factors influencing the chloroform concentration in the air. When the number of swimmers surpassed 40, the concentrations of chloroform were on average 4.4 times higher than the concentration measured without swimmers in the pool. According to the results of this study, we suggest that those who swim regularly should avoid times with highest number of swimmers, in order to decrease the risk of exposure to high concentrations of chloroform. It is also recommended that an automatic mechanical ventilation system is installed to increase the ventilation rate during times of high swimmer load.     

Characteristics of trihalomethane (THM) production and associated health risk assessment in swimming pool waters treated with different disinfection methods

Swimming pool water must be treated to prevent infections caused by microbial pathogens. In Korea, the most commonly used disinfection methods include the application of chlorine, ozone/chlorine, and a technique that uses electrochemically generated mixed oxidants (EGMOs). The purpose of this study was to estimate the concentrations of total trihalomethanes (TTHMs) in indoor swimming pools adopting these disinfection methods, and to examine the correlations between the concentrations of THMs and TTHMs and other factors affecting the production of THMs. We also estimated the lifetime cancer risks associated with various exposure pathways by THMs in swimming pools. Water samples were collected from 183 indoor swimming pools in Seoul, Korea, and were analyzed for concentrations of each THM, TOC, and the amount of KMnO₄ consumption. The free chlorine residual and the pH of the pool water samples were also measured. The geometric mean concentrations of TTHMs in the swimming pool waters were 32.9 ± 2.4 µg/L for chlorine, 23.3 ± 2.2 µg/L for ozone/chlorine, and 58.2 ± 1.7 µg/L for EGMO. The concentrations of THMs differed significantly among the three treatment methods, and the correlation between THMs and TTHMs and the other factors influencing THMs varied. The lifetime cancer risk estimation showed that, while risks from oral ingestion and dermal exposure to THMs are mostly less than 10^− 6, which is the negligible risk level defined by the US EPA, however swimmers can be at the greater risk from inhalation exposure (7.77 × 10^− 4-1.36 × 10^− 3).     

An analytical method for the analysis of trihalomethanes in ambient air using solid‐phase microextraction gas chromatography‐mass spectrometry: An application to indoor swimming pool complexes

A simple method for the collection and analysis of the four brominated and chlorinated trihalomethanes (THMs) in air samples is described. Ambient air samples were collected in pre‐prepared glass vials, with THM analysis performed using solid‐phase microextraction gas chromatography‐mass spectrometry, where the need for chemical reagents is minimized. Analytical parameters, including oven temperature program, solvent volume, incubation time, vial agitation, extraction time and temperature, as well as desorption time and temperature, were evaluated to ensure optimal method performance. The developed method allows for point‐in‐time quantification (compared to an average concentration measured over extended periods of time), with detection limits between 0.7 to 2.6 µg/m³. Excellent linearity (r² > 0.99), repeatability (3% to 11% RSD), and reproducibility (3% to 16% RSD) were demonstrated over a concentration range from 2 to 5000 µg/m³. The method was validated for the analysis of THMs in indoor swimming pool air and was used to investigate the occurrence of THMs in the air above 15 indoor swimming pools. This is the first study to report the occurrence of THMs in swimming pool air in Australia, and concentrations higher than those previously reported in other countries were measured.     

阳泉一中体育中心室内游泳池给排水设计

结合设计实例 ,对室内游泳池的给排水设计作了简单介绍 ,指出应根据实际情况及甲方的要求 ,在设计中对工程投资及适用性予以重视     

Removal of submicron particles using a carbon fiber ionizer-assisted medium air filter in a heating,ventilation, and air-conditioning (HVAC) system

Laboratory tests of particle removal were performed with a pair of carbon fiber ionizers installed upstream of a glass fiber air filter. For air flow face velocities of 0.4, 0.6, and 0.8 m/s, the overall particle removal efficiencies of the filter for all submicron particles were 17%, 16%, and 14%, respectively, when the ionizers were not turned on. These values increased to 27%, 23%, and 19%, respectively, when the ionizers were used to generate ions of 6.0 × 10⁹ ions/cm³ in concentration. The carbon fiber ionizers were then installed in front of a glass fiber air filter located in a heating, ventilation, and air-conditioning (HVAC) system. Field tests were performed in a test office room with a total indoor particle concentration of 2.2 × 10⁴ particles/cm³. When the flow rate was 75 cubic meters per hour (CMH), the steady-state values of the total indoor particle concentrations using the glass fiber air filter with and without ionizers decreased to 0.87 × 10⁴ particles/cm³ and 1.15 × 10⁴ particles/cm³, respectively, resulting in a 25% decrease of the ionizer effect. When the operation flow rate was increased to 115 and 150 CMH, the effect of the ionizer decreased to 19% and 17%, respectively. These experimental data match the results calculated using a mass-balance model whose parameters were determined from laboratory tests.     

Characterizations,relationship, and potential sources of outdoor and indoor particulate matter bound polycyclic aromatic hydrocarbons (PAHs) in a community of Tianjin,Northern China

Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic air pollutants in China. However, because there are unsubstantial data on indoor and outdoor particulate PAHs, efforts in assessing inhalation exposure and cancer risk to PAHs are limited in China. This study measured 12 individual PAHs in indoor and outdoor environments at 36 homes during the non‐heating period and heating period in 2009. Indoor PAH concentrations were comparable with outdoor environments in the non‐heating period, but were lower in the heating period. The average indoor/outdoor ratios in both sampling periods were lower than 1, while the ratios in the non‐heating period were higher than those in the heating period. Correlation analysis and coefficient of divergence also verified the difference between indoor and outdoor PAHs, which could be caused by high ventilation in the non‐heating period. To support this conclusion, linear and robust regressions were used to estimate the infiltration factor to compare outdoor PAHs to indoor PAHs. The calculated infiltration factors obtained by the two models were similar in the non‐heating period but varied greatly in the heating period, which may have been caused by the influence of ventilation. Potential sources were distinguished using a diagnostic ratio and a mixture of coal combustion and traffic emission, which are major sources of PAHs.     

Multivariable control of indoor air temperature and humidity in a direct expansion (DX) air conditioning (A/C) system

Controlling indoor humidity at an appropriate level is very important since this affects occupants' thermal comfort and indoor air quality (IAQ). The paper presents an investigation on developing a multi-input multi-output (MIMO) control strategy for simultaneously controlling the indoor air temperature and humidity by varying the speeds of both compressor and supply fan in an experimental DX A/C system. The MIMO-based controller was designed based on the linearized dynamic model of the experimental DX A/C system. The Linear Quadratic Gaussian (LQG) technique was used in designing the MIMO-based controller. The controllability tests with respect to both the disturbance rejection capability and the command following capability were carried out to assess the control performance of MIMO controller. The results of disturbance rejection capability test showed that the MIMO control strategy can effectively maintain the indoor air temperature and humidity to their respective settings after an unmeasured heat load disturbance was imposed by simultaneously varying speeds of both the compressor and the supply fan of the DX A/C system. Furthermore, in the command following capability test for indoor air temperature, the test results showed that the indoor air temperature can be controlled to its new setting while indoor humidity remained unchanged. Similar test results were also observed in the command following capability test for indoor humidity. Therefore, the MIMO controller developed can effectively control indoor air temperature and humidity simultaneously by varying compressor speed and supply fan speed of the DX A/C system. Compared to the previous related studies using conventional on–off control method or single-input single-output (SISO) control strategy, which can only effectively control either air temperature or relative humidity, the MIMO controller can simultaneously control the indoor air temperature and humidity with adequate control sensitivity and accuracy. The application of MIMO control strategy developed can be extended to other HVAC systems in the future to improve their operating performance and energy efficiency.     

广州市国际生物岛标准产业单元建设(三期)暖通空调设计

结合广州市国际生物岛标准产业单元建设(三期)工程的实例,简要介绍了该工程主体建筑内部暖通空调系统及地下车库通风排烟系统设计。通过对一个具体工程的主要暖通空调系统介绍,及与以往多个已设计的工程暖通空调系统作比较,说明了暖通空调专业在该项目中是如何利用新技术、新设备及新方法更好地满足建筑节能设计要求的。     

Bioaccumulation of As, Cd, Cr, Hg(II), and MeHg in killifish (Fundulus heteroclitus) from amphipod and worm prey

Elevated metal levels in fish are a concern for the fish themselves, their predators, and possibly humans who consume contaminated seafood. Metal bioaccumulation models often rely on assimilation efficiencies (AEs) of ingested metals and loss rate constants after dietary exposure (k_efs). These models can be used to better understand processes regulating metal accumulation and can be used to make site-specific predictions of metal concentrations in animal tissues. Fish often consume a varied diet, and prey choice can influence these two parameters. We investigated the trophic transfer of As, Cd, Cr, Hg(II), and methylmercury (MeHg) from a benthic amphipod (Leptocheirus plumulosus) and an oligochaete (Lumbriculus variegatus) to killifish (Fundulus heteroclitus) using gamma-emitting radioisotopes. Except for MeHg, AEs varied between prey type. AEs were highest for MeHg (92%) and lowest for Cd (2.9-4.5%) and Cr (0.2-4%). Hg(II) showed the largest AE difference between prey type (14% amphipods, 24% worms). For Cd and Hg(II) k_efs were higher after consuming amphipods than consuming worms. Tissue distribution data shows that Cd and Hg(II) were mainly associated with the intestine, whereas As and MeHg were transported throughout the body. Calculated trophic transfer factors (TTFs) suggest that MeHg is likely to biomagnify at this trophic step at all ingestion rates, whereas As, Cd, Cr, and Hg(II) will not. Data collected in this study and others indicate that using one prey item to calculate AE and k_ef could lead to an over- or underestimation of these parameters.     

Survey of volatile halogenated organics (VHO) in Italy: Levels of VHO in drinking waters, surface waters and swimming pools

A survey undertaken in Italy (Emilia-Romagna region) has shown that Volatile Halogenated Organics (VHO) are present in many water samples; analysis has been performed by static head-space gas chromatographic technique.In drinking water samples low levels of pollution have become evident before any treatment, while after chlorination with sodium hypochlorite, or chlorine as a gas, VHO have appeared, almost exclusively as trihalomethanes (THM), sometimes at fairly high levels (max = 41.8 μg l⁻¹).Surface water samples have been collected every other month in one year, and have shown different levels of contamination; in most cases VHO (mainly chlorinated solvents) appeared just as traces, seldom at high concentration (max = 263 μg l⁻¹).Swimming pool samples have shown the high levels of contamination (max = 177.4 μg l⁻¹), mainly due to THM, as a consequence of chlorination with sodium hypochlorite.As a matter of fact, it has become evident that VHO pollution is wide-spread in every kind of water; while contamination of surface waters can only involve environmental and aquatic life, contamination especially of drinking waters, and also of swimming pool waters must be controlled as it can directly act on human health.     

Diastereomer-specific bioaccumulation of hexabromocyclododecane (HBCD) in a coastal food web, Western Norway

The present study reports diastereomer-specific accumulation of HBCD from a point source in five marine species representing a typical food web in a Norwegian coastal area. Samples of mussels, polychaetes, crabs and seabird eggs were analyzed for the diastereomers α-, β- and γ-HBCD, as well as lipid content and stable isotopes of nitrogen (¹⁵N/¹⁴N) to estimate trophic level. Accumulated HBCD did not correlate well with lipid content for most of the species, thus wet-weight based concentrations were included in an assessment of biomagnification. In contrast to β- and γ-HBCD, the α-diastereomer increased significantly with trophic level, resulting in magnification factors > 1 in this coastal marine ecosystem. Data for poikilotherms did not show the same positive correlation between the α-diastereomer and trophic position as homeotherms. The apparent biomagnification of the α-HBCD could be due to bioisomerization or diastereomer-specific elimination that differed between poikilotherms and homeotherms.     

Spatial and temporal changes of chlorinated pesticides, PCBs, dioxins (PCDDs/PCDFs) and brominated flame retardants in human breast milk from Northern Russia

This study presents for the first time temporal changes of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Russian human breast milk samples. Concentrations of OCPs and PCBs in samples from three locations in the North West of Russia in 2000-2002 (n=42), were compared to corresponding levels measured in 1993-1996 (n=58). In addition brominated flame retardants (BFRs), consisting of polybrominated diphenylethers (PBDEs) (including BDE-209) and hexabromocyclododecane (HBCD) were analysed in samples from 2000-2002 (n=37). The present levels of SigmaDDTs and SigmaHCHs were 5 and 10 times higher than corresponding levels in the neighbouring country Norway. Median concentrations of SigmaHCHs (196 microg/kg lw), SigmaCHBs (19.7 microg/kg lw) and SigmaPCBs(16) (316 microg/kg lw) were highest in Murmansk. The percentage of p,p'-DDT to SigmaDDTs and ratio DDE/DDT suggest possible ongoing use of DDT in Russia. Levels of PBDE were low and dominated by the congeners BDE-47 and BDE-153. The deca brominated BDE-209 was detected in all analysed samples (median concentration 0.19 microg/kg lipid). Levels of SigmaOCPs and SigmaPCBs decreased 56 and 30% in Murmansk and 36 and 43% in Arkhangelsk during the study period. The decline of SigmaOCPs was significant at both locations (p<0.05-p<0.0001). For SigmaPCBs, the decreasing trend was only significant in Arkhangelsk (p<0.0001). In addition, a decline of Sigmatotal TEQs (SigmaTEQs of PCDDs/PCDFs, non-ortho- and mono-ortho PCBs) was observed in Murmansk and Arkhangelsk during the study period. The exposure of infants by PCDDs/PCDFs and dioxin-like PCBs is still exceeding the daily tolerable intake (TDI) in North West Russia. However, the concentrations of PCDDs/PCDFs and dioxin-like PCBs seem to decline very rapidly.     

空调大温差研究(3):空调送风大温差经济分析

对采用空调大温差的办公楼、工厂及商场分别进行经济比较,结果表明在各种条件下,增大送同温差,空调系统的一次投资和运行费用都可以减少,同时室内相对湿度的降低可以明显提高人体舒适感,改善室内空气品质。     

Modeling residential indoor concentrations of PM2.5, NO2, NOx,and secondhand smoke in the Subpopulations and Intermediate Outcome Measures in COPD (SPIROMICS) Air study

Increased outdoor concentrations of fine particulate matter (PM_2.5) and oxides of nitrogen (NO₂, NO_x) are associated with respiratory and cardiovascular morbidity in adults and children. However, people spend most of their time indoors and this is particularly true for individuals with chronic obstructive pulmonary disease (COPD). Both outdoor and indoor air pollution may accelerate lung function loss in individuals with COPD, but it is not feasible to measure indoor pollutant concentrations in all participants in large cohort studies. We aimed to understand indoor exposures in a cohort of adults (SPIROMICS Air, the SubPopulations and Intermediate Outcome Measures in COPD Study of Air pollution). We developed models for the entire cohort based on monitoring in a subset of homes, to predict mean 2-week–measured concentrations of PM_2.5, NO₂, NO_x, and nicotine, using home and behavioral questionnaire responses available in the full cohort. Models incorporating socioeconomic, meteorological, behavioral, and residential information together explained about 60% of the variation in indoor concentration of each pollutant. Cross-validated R² for best indoor prediction models ranged from 0.43 (NO_x) to 0.51 (NO₂). Models based on questionnaire responses and estimated outdoor concentrations successfully explained most variation in indoor PM_2.5, NO₂, NO_x, and nicotine concentrations.     

公共建筑空调系统运行调适方法研究(3):冷水机组

通过对实际项目的详细测试和数据分析,从外因、内因以及内外协同三方面入手,总结了常规工频冷水机组和变频冷水机组实际运行过程中存在的共性问题和特性问题。针对存在的典型问题,提出了冷水机组运行调适方法,为冷水机组运行性能的提升指明了节能方向。     

国内外蒸发冷却空调技术研究进展(3)

介绍了多级蒸发冷却空调系统、除湿与蒸发冷却相结合的空调系统、半集中式蒸发冷却空调系统、建筑物被动蒸发冷却技术、蒸发冷却自动控制系统及蒸发冷却水的水质处理。     

开元寺天王殿建筑构造（二）

广东潮州开元寺天王殿1981~1983年进行落架大修。通过对开元寺进行整体勘察，发现天王殿平面进深与面阔之比与现存唐宋时期建筑部分相差较大。厅堂结构体系与佛光寺相比，二者平面柱网相似，而上部梁架则差异甚大。立面与山门装修做法使位于末间中槽之天王像不致于显露其侧面。天王殿梁架由明、次、稍、尽间以及厦头、转角五种不同形式组成，均为典型的柱梁排架式结构，明、次间屋架几乎全由铰打叠斗代替梁上矮柱。殿内石柱刻联记载了历代营修。最终经过一系列比对和研究，确定了天王殿修缮方案。     

Measurement and source identification of polycyclic aromatic hydrocarbons (PAHs) in the aerosol in Xi'an, China, by using automated column chromatography and applying positive matrix factorization (PMF)

In this study, we measured polycyclic aromatic hydrocarbons (PAHs) in aerosols in Xi'an, China from 2005 to 2007, by using a modified Soxhlet extraction followed by a clean-up procedure using automated column chromatography followed by HPLC/fluorescence detection. The sources of PAHs were apportioned by using the positive matrix factorization (PMF) method. The PM₁₀ concentration in winter (161.1 ± 66.4 μg m^− 3, n = 242) was 1.5 times higher than that in summer (110.9 ± 34.7 μg m^− 3, n = 248). ΣPAH concentrations, which are the sum of the concentrations of all detected PAHs, in winter (344.2 ± 149.7 ng m^− 3, n = 45) was 2.5 times higher than that in summer (136.7 ± 56.7 ng m^− 3, n = 24) in this study. These strong seasonal variations in atmospheric PAH concentration are possibly due to coal combustion for residential heating. According to the source apportionment with PMF method in this study, the major sources of PAHs in Xi'an are categorized as (1) mobile sources such as vehicle exhaust that constantly contribute to PAH pollution, and (2) stationary sources such as coal combustion that have a large contribution to PAH pollution in winter.