From air to clothing: characterizing the accumulation of semi‐volatile organic compounds to fabrics in indoor environments

Uptake kinetics of semi‐volatile organic compounds (SVOCs) present indoors, namely phthalates and halogenated flame retardants (HFRs), were characterized for cellulose‐based cotton and rayon fabrics. Cotton and rayon showed similar accumulation of gas‐ and particle‐phase SVOCs, when normalized to planar surface area. Accumulation was 3–10 times greater by rayon than cotton, when normalized to Brunauer–Emmett–Teller (BET) specific surface area which suggests that cotton could have a longer linear uptake phase than rayon. Linear uptake rates of eight consistently detected HFRs over 56 days of 0.35–0.92 m³/day.dm² planar surface area and mass transfer coefficients of 1.5–3.8 m/h were statistically similar for cotton and rayon and similar to those for uptake to passive air sampling media. These results suggest air‐side controlled uptake and that, on average, 2 m² of clothing typically worn by a person would sequester the equivalent of the chemical content in 100 m³ of air per day. Distribution coefficients between fabric and air (K′) ranged from 6.5 to 7.7 (log K′) and were within the range of partition coefficients measured for selected phthalates as reported in the literature. The distribution coefficients were similar for low molecular weight HFRs, and up to two orders of magnitude lower than the equilibrium partition coefficients estimated using the COSMO‐RS model. Based on the COSMO‐RS model, time to reach 95% of equilibrium for PBDEs between fabric and gas‐phase compounds ranged from 0.1 to >10 years for low to high molecular weight HFRs.     

A fugacity based continuous and dynamic fate and transport model for river networks and its application to Altamaha River

In this paper, a continuous and dynamic fugacity-based contaminant fate and transport model is developed. The dynamic interactions among all phases in the physical domain are addressed through the use of the fugacity approach instead of the use of concentration as the unknown variable. The full form of Saint Venant equations is used in order to solve for the hydrodynamic conditions in the river network. Then a fugacity-based advection-dispersion equation is modeled to examine the fate and transport of contaminants in the river network for all phases.The fugacity-based, dynamic and continuous contaminant fate and transport model developed here is applied to Altamaha River in Georgia, USA to demonstrate its use in environmental exposure analysis. Altamaha River is the largest river system east of Mississippi which offers habitat for many species, including about 100 rare endangered species, along its 140 mile course. Polychlorinated biphenyls (PCBs), a highly hydrophobic and toxic chemical ubiquitous in nature, and atrazine, the most commonly-used agricultural pesticide are modeled as contaminants in this demonstration. Through this approach the concentration distribution of PCBs and atrazine in the water column of Altamaha River as well as the sediments can be obtained with relative ease, which is an improvement over concentration based analysis of phase distribution of contaminants.     

A chemical dynamic model for the infiltration of outdoor size-resolved ammonium nitrate aerosols to indoor environments

In the present study, we developed a chemical dynamic model to describe the infiltration of size-resolved ammonium nitrate aerosols from outdoor to indoor environments. This model considered the penetration factor, deposition rate, and the reversible reaction process, which was quantified by the diffusive molar flux on the surface of ammonium nitrate aerosols depending on indoor temperature, humidity, and concentrations of nitric acid (HNO₃) and ammonia (NH₃). To verify the model, we employed a single-particle aerosol mass spectrometer with an automated switching system to simultaneously measure size-resolved outdoor and indoor ammonium nitrate aerosols. Comparisons between the predicted and measured concentrations of these aerosols showed a mean relative error of 4.8 ± 18.3%. To analyze the sensitivity of model parameters, several parameters were perturbed. This analysis indicated that parameters related to HNO₃ were more sensitive than those related to NH₃ because the indoor gas phase concentration of NH₃ was much higher than that of HNO₃.     

A mechanistic model of runoff-associated fecal coliform fate and transport through a coastal lagoon

Fecal coliform (FC) contamination in coastal waters is an ongoing public health problem worldwide. Coastal wetlands and lagoons are typically expected to protect coastal waters by attenuating watershed pollutants including FC bacteria. However, new evidence suggests that coastal lagoons or marshes can also be a source of high indicator organism concentrations in coastal waters. We asked for a Mediterranean-type climate, what is the fate of runoff-associated FC through a coastal lagoon? To address this question, we developed a mass balance-based, mechanistic model of FC concentration through a coastal lagoon and simulated, for summer and winter conditions, FC within the lagoon water column, lagoon sediments, and in the ocean water just downstream of the lagoon mouth. Our model accounts for advective flow and dispersion, decay and sedimentation and resuspension of FC-laden sediments during high flow, erosional conditions. Under low flow conditions that occur in the summer, net FC decay and FC storage in lagoon sediments are predicted. Under high flow conditions that occur in the winter, FC-laden sediments are predicted to erode, resuspend and flow out of the lagoon where they elevate FC concentrations in the coastal ocean. For both seasonal conditions, the predicted water column FC concentrations were within an order of magnitude of field measurements for a reference site in southern California. Our results suggest that there are seasonally varying roles for coastal lagoons in mediating FC contamination to coastal waters.     

Modeling the viral load dependence of residence times of virus-laden droplets from COVID-19-infected subjects in indoor environments

In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus-laden droplets (termed as “virusol”) (Anand and Mayya, 2020). Herein we develop the theory of residence time of the virusols, as contrasted with complete droplet system in indoor air using a comprehensive “Falling-to-Mixing-Plate-out” model that considers all the important processes namely, indoor dispersion of the emitted puff, droplet evaporation, gravitational settling, and plate out mechanisms at indoor surfaces. This model fills the existing gap between Wells falling drop model (Wells, 1934) and the stirred chamber models (Lai and Nazarofff, 2000). The analytical solutions are obtained for both 1-D and 3-D problems for non-evaporating falling droplets, used mainly for benchmarking the numerical formulation. The effect of various parameters is examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from about 100 to 150 s at low viral loads (<10⁴/ml) to about 1100–1250 s at high viral loads (>10¹¹/ml). The implications are discussed.     

Identification of the major HOx radical pathways in an indoor air environment

OH and HO₂ profiles measured in a real environment have been compared to the results of the INCA‐Indoor model to improve our understanding of indoor chemistry. Significant levels of both radicals have been measured and their profiles display similar diurnal behavior, reaching peak concentrations during direct sunlight (up to 1.6×10⁶ and 4.0×10⁷ cm^?3 for OH and HO₂, respectively). Concentrations of O₃, NO_x, volatile organic compounds (VOCs), HONO, and photolysis frequencies were constrained to the observed values. The HO_x profiles are well simulated in terms of variation for both species (Pearson's coefficients: p_OH=0.55, p_HO2=0.76) and concentration for OH (mean normalized bias error: MNBE_OH=?30%), HO₂ concentration being always underestimated (MNBE_HO2=?62%). Production and loss pathways analysis confirmed HONO photolysis role as an OH precursor (here up to 50% of the production rate). HO₂ formation is linked to OH‐initiated VOC oxidation. A sensitivity analysis was conducted by varying HONO, VOCs, and NO concentrations. OH, HO₂, and formaldehyde concentrations increase with HONO concentrations; OH and formaldehyde concentrations are weakly dependent on NO, whereas HO₂ concentrations are strongly reduced with increasing NO. Increasing VOC concentrations decreases OH by consumption and enhances HO₂ and formaldehyde.     

A model for predicting resuspension of Escherichia coli from streambed sediments

To improve the modeling of water quality in watersheds, a model is developed to predict resuspension of Escherichia coli from sediment beds in streams. The resuspension rate is expressed as the product of the concentration of E. coli attached to sediment particles and an erosion rate adapted from work on sediment transport. The model uses parameter values mostly taken from previous work, and it accounts for properties of the flow through the bottom shear stress and properties of the sediment through the critical shear stresses for cohesive and non-cohesive sediment. Predictions were compared to resuspension rates inferred from a steady mass balance applied to measurements at sixteen locations in a watershed. The model’s predictions matched the inferred rates well, especially when the diameter of particles to which E. coli attach was allowed to depend on the bottom shear stress. The model’s sensitivity to the parameters depends on the contributions of particle packing and binding effects of clay to the critical shear stress. For the current data set, the uncertainty in the predictions is controlled by the concentration of E. coli attached to sediment particles and the slope used to estimate the bottom shear stress.     

大连沈阳夏季室内热湿环境状况的实测调查

通过对大连市和沈阳市8套住宅夏季室内温湿度的实测调查，分析了室外气候条件、住宅形式、人员活动及空调设备使用情况对室内热湿环境的影响，为了解目前北方地区现有住宅夏季室内热湿环境状况提供了参考。     

Quantification of alkenes on indoor surfaces and implications for chemical sources and sinks

Indoor surfaces are known to support organic films, but their thickness, composition, and variability between environments remain poorly characterized. Alkenes are expected to be a significant component of these films, with the reaction with O₃ being a major sink for O₃ and source of airborne chemicals. Here, we present a sensitive, microscale, nanospectrophotometric method for quantifying the alkene (C=C bond) content of surface films and demonstrate its applicability in five studies relevant to indoor air chemistry. Collection efficiencies determined for a filter wipe method were ~64%, and the overall detection limit for monoalkenes was ~10 nmol m⁻². On average, painted walls and glass windows sampled across the University of Colorado Boulder campus were coated by ~4 nm thick films containing ~20% alkenes, and a simple calculation indicates that the lifetime for these alkenes due to reaction with O₃ is ~1 hour, indicating that the films are highly dynamic. Measurements of alkenes in films of skin oil, pan-fried cooking oils, a terpene-containing cleaner, and on various surfaces in a closed classroom overnight (where carboxyl groups were also measured) provided insight into the effects of chemical and physical processes on film and air composition.     

Mathematical model for predicting microbial reduction and transport of arsenic in groundwater systems

A mathematical model was developed for describing the transport of arsenic, coupled with microbially-mediated biogeochemical processes. The biogeochemical characteristics of arsenic reactive transport processes were investigated in both batch and column tests, which showed that As(V) was reduced to As(III) by Shewanella sp., with the reduced arsenic species subsequently removed by precipitation. The breakthrough data obtained from the column experiments were used for the calibration of the arsenic reactive transport model. The reactive transport model, which only incorporated microbial reduction processes, showed a large discrepancy in predicting the observed As(III) concentration profiles, particularly later in the experiments. However, the model matched the experimental data much better with the inclusion of a term describing the precipitation process. Our results indicated that the precipitation reaction can be a major sink during microbially-mediated arsenic reactive transport. The proposed model provides a useful framework for predicting the transport of arsenic in saturated groundwater aquifers.     

Simulation of alachlor fate and transport: model calibration and sensitivity analysis

Spraying of agricultural chemicals result in their travel downward through the unsaturated zone and adsorption on the surrounding soil. Infiltration from rainfall and irrigation solubilize these chemicals and carry the dissolved components to the ground water. This process can cause soil and ground water contamination the extent of which is greatly influenced by soil characteristics, the rate and method of chemical application. This paper presents experimental and mathematical results describing the transport of the herbicide Alachlor in laboratory soil columns with variable length, initial moisture content, and Alachlor application rate and method. The laboratory time‐dependent distribution of Alachlor concentration is used to calibrate a numerical flow and transport model. The model was also used to conduct a sensitivity analysis with respect to soil and chemical properties and identify parameters value ranges controlling Alachlor transport in porous media.     

Geographically distributed classification of surface water chemical parameters influencing fate and behavior of nanoparticles and colloid facilitated contaminant transport

The current production and use of nanomaterials in consumer products have increased the concern about the possibility that these enter the rivers during their entire life cycle. Further, many aquatic contaminants undergo partitioning to the ubiquitous aquatic colloids. Here is presented the development of a set of European water types for environmental risk assessment of chemicals transported as nanovectors as is the case of environmental fate of manufactured nanoparticles and colloid-bound contaminants.     

输沙模型在桥梁一般冲刷上的应用分析

对根据输沙平衡原理及冲止流速概念建立的一般冲刷公式（2）和公式（1）进行了介绍，利用一维恒定饱和输沙模型，对压缩河道的河床冲刷进行了数值计算并得出冲刷规律，以推广输沙模型的应用。     

双酚A在环境中迁移转化的研究进展

分析了内分泌干扰物对人和动物的影响,介绍了其在化学工业中的应用,阐述了双酚A的基本性质、用途、危害和环境存在性等,从吸附、光降解和生物降解等几方面综述了双酚A在环境中迁移转化的研究进展。     

A state space model for predicting and controlling the temperature responses of indoor air zones

Indoor temperature distributions and air flows lead to the variation of local thermal comfort from place to place. To have more precise predictions and better control of the thermal conditions in the working zone where the room occupant sits and works, a both detailed and fast model of the dynamic indoor temperature distributions is needed. Unfortunately, very few papers studied such models due to the complexity of fluid (air) flows. This paper discusses a zonal model which is derived from computational fluid dynamics (CFD) and the output of a CFD code. The model is validated with experimental results. In order to design better control systems, the zonal model is transformed into a state space representation form. One example is given on how the state space model can be used for temperature predictions and more precise temperature controls.     

A multiple model approach for predictive control of indoor thermal environment with high resolution

Realtime and precise control strategies for indoor micro-climate are increasingly needed due to the requirements of thermal comfort and energy consumption saving in recent years. In this paper, a precise control scheme with high resolution is proposed for indoor thermal regulation. Finite volume method discretization/linearization are employed to construct the state-space model of the thermal process. Proper orthogonal decomposition method is further applied for model order reduction. On this basis, a multiple model approach is used to treat the thermodynamic coupling effect and a multi-model switching model predictive control (MPC) scheme is proposed for temperature tracking. Two cases including cooling and warming scenarios are designed, respectively, for performance validation. Results show that compared with the classic MPC method, the developed method can alleviate the model mismatch problem, and facilitate an optimal control of the spatial temperature in the considered ventilation room.     

Profiles and seasonal distribution of airborne fungi in indoor and outdoor environments at a French hospital

A one-year prospective survey of fungal air contamination was conducted in outdoor air and inside two haematological units of a French hospital. Air was sampled with a portable Air System Impactor. During this period of survey, the mean viable fungal load was 122.1 cfu/m³ in outdoor air samples, and 4.1 and 3.9 cfu/m³ in samples from adult and pediatric haematology units, respectively. In outdoor samples, Cladosporium was the dominant genus (55%) while in the clinical units, Penicillium sp. (23 to 25%), Aspergillus sp. (15 to 23%) and Bjerkandera adusta (11 to 13%) were the most frequently recovered airborne fungi. The outdoor fungal load was far higher in autumn (168 cfu/m³), spring (110 cfu/m³) and summer (138 cfu/m³) than in winter (49 cfu/m³). In indoor air, fungal concentrations were significantly lower in winter (2.7 to 3.1 cfu/m³) than in summer (4.2 to 5.0 cfu/m³) in both haematology units. In the outdoor environment, Penicillium sp. and Aspergillus sp. were more abundant in winter while the levels of Cladosporium were lowest during this season. In the haematological units, the presence of Aspergillus sp. was stable during the year (close to 20%), Bjerkandera sp. was particularly abundant in winter (close to 30%); levels of Penicillium sp. were highest in autumn while levels of Cladosporium sp. were highest in spring and summer.     

An institutional model for land use and transport integration

The integration of land use planning and transport planning to achieve sustainable travel behaviour has been espoused as a desirable outcome for many years. Development and establishment of appropriate institutional arrangements coupled with effective policy and planning processes is a crucial component in the achievement of this desirable outcome. The merging of the Western Australian Government's planning and transport agencies in 2001 provided the catalyst for the development of this institutional model with the aim to achieve desired land use and transport integration outcomes. The model draws together principles of transport planning, land use planning, public policy and organisational behaviour. A local case study illustrates the potential for the model's application in practice. An organisational structure is suggested that employs a matrix style approach, akin to a project-based approach, drawing on the multidisciplinary skills within the planning and infrastructure portfolio, and using the full range of non-traditional resources.