Geographical scenario uncertainty in generic fate and exposure factors of toxic pollutants for life-cycle impact assessment

In environmental life-cycle assessments (LCA), fate and exposure factors account for the general fate and exposure properties of chemicals under generic environmental conditions by means of 'evaluative' multi-media fate and exposure box models. To assess the effect of using different generic environmental conditions, fate and exposure factors of chemicals emitted under typical conditions of (1).Western Europe, (2). Australia and (3). the United States of America were compared with the multi-media fate and exposure box model USES-LCA. Comparing the results of the three evaluative environments, it was found that the uncertainty in fate and exposure factors for ecosystems and humans due to choice of an evaluative environment, as represented by the ratio of the 97.5th and 50th percentile, is between a factor 2 and 10. Particularly, fate and exposure factors of emissions causing effects in fresh water ecosystems and effects on human health have relatively high uncertainty. This uncertainty is mainly caused by the continental difference in the average soil erosion rate, the dimensions of the fresh water and agricultural soil compartment, and the fraction of drinking water coming from ground water.     

Parameter evaluation and model validation of ozone exposure assessment using Harvard Southern California Chronic Ozone Exposure Study data

To examine factors influencing long-term ozone (O3) exposures by children living in urban communities, the authors analyzed longitudinal data on personal, indoor, and outdoor O3 concentrations, as well as related housing and other questionnaire information collected in the one-year-long Harvard Southern California Chronic Ozone Exposure Study. Of 224 children contained in the original data set, 160 children were found to have longitudinal measurements of O3 concentrations in at least six months of 12 months of the study period. Data for these children were randomly split into two equal sets: one for model development and the other for model validation. Mixed models with various variance-covariance structures were developed to evaluate statistically important predictors for chronic personal ozone exposures. Model predictions were then validated against the field measurements using an empirical best-linear unbiased prediction technique. The results of model fitting showed that the most important predictors for personal ozone exposure include indoor O3 concentration, central ambient O3 concentration, outdoor O3 concentration, season, gender, outdoor time, house fan usage, and the presence of a gas range in the house. Hierarchical models of personal O3 concentrations indicate the following levels of explanatory power for each of the predictive models: indoor and outdoor O3 concentrations plus questionnaire variables, central and indoor O3 concentrations plus questionnaire variables, indoor O3 concentrations plus questionnaire variables, central O3 concentrations plus questionnaire variables, and questionnaire data alone on time activity and housing characteristics. These results provide important information on key predictors of chronic human exposures to ambient O3 for children and offer insights into how to reliably and cost-effectively predict personal O3 exposures in the future. Furthermore, the techniques and findings derived from this study also have strong implications for selecting the most reliable and cost-effective exposure study design and modeling approaches for other ambient pollutants, such as fine particulate matter and selected urban air toxics.     

Biodegradability of the antioxidant diaryl-p-phenylene diamine using a modified inherent biodegradation method at an environmentally relevant concentration

The chemical product diaryl-p-phenylene diamine (DAPD), produced by The Goodyear Tire & Rubber Company as POLYSTAY 100® (CAS 68953-84-4), is employed as an antidegradant in polymers used in tires and industrial rubber products. Previous evaluations pertaining to the ecological fate of DAPD indicated a lack of biodegradative activity in aquatic media. In order to further pursue the biodegradation potential of DAPD, it was deemed necessary to enhance the sensitivity of the aquatic biodegradation assay through (a) employment of a radiotracer of the test substance, and (b) optimisation of conditions for achieving maximal solubilisation of test material in the aquatic media of the incubation vessels. Test vessels were prepared according to the OECD ready biodegradability test guidelines, with DAPD added on silica gel at concentrations of 10 or 100 μg L⁻¹, together with a surfactant to aid solubilisation. After 63 d incubation up to 37% mineralisation was measured and up to 29% of the applied radioactivity was incorporated into cell biomass. Also, after 28 d no DAPD could be measured in solution by radio-TLC and HPLC–MS. These three results demonstrate that the antioxidant DAPD undergoes microbiologically mediated biodegradation and is highly unlikely to persist in the environment.     

A real-time,dynamic early-warning model based on uncertainty analysis and risk assessment for sudden water pollution accidents

A real-time, dynamic, early-warning model (EP-risk model) is proposed to cope with sudden water quality pollution accidents affecting downstream areas with raw-water intakes (denoted as EPs). The EP-risk model outputs the risk level of water pollution at the EP by calculating the likelihood of pollution and evaluating the impact of pollution. A generalized form of the EP-risk model for river pollution accidents based on Monte Carlo simulation, the analytic hierarchy process (AHP) method, and the risk matrix method is proposed. The likelihood of water pollution at the EP is calculated by the Monte Carlo method, which is used for uncertainty analysis of pollutants’ transport in rivers. The impact of water pollution at the EP is evaluated by expert knowledge and the results of Monte Carlo simulation based on the analytic hierarchy process. The final risk level of water pollution at the EP is determined by the risk matrix method. A case study of the proposed method is illustrated with a phenol spill accident in China.     

Atmospheric dispersion in the presence of a three-dimensional cubical obstacle: Modelling of mean concentration and concentration fluctuations

This paper presents computational simulations of atmospheric dispersion experiments conducted around isolated obstacles in the field. The computational tool used for the simulations was the code ADREA-HF, which was especially developed for the simulation of the dispersion of positively or negatively buoyant gases in complicated geometries. The field experiments simulated involve a single cubic obstacle normal to the mean wind direction and two upwind sources of ammonia and propane, with the ammonia source located at different lateral positions [Mavroidis, I., Griffiths, R.F., Hall, D.J., 2003. Field and wind tunnel investigations of plume dispersion around single surface obstacles. Atmospheric Environment 37, 2903–2918]. Concentrations and concentration fluctuations for both gases were calculated by the model and compared with the experimental results. Certain modelling aspects were studied, such as the effect of using different turbulence closure schemes in the computations. Furthermore, specific characteristics of dispersion were investigated using the computational tool, such as the effect of the lateral displacement of a source on the concentration fluctuations intensity, the effects of natural variability and the sensitivity of concentrations to wind direction fluctuations. The results showed a good level of agreement between calculated and measured concentrations and concentration fluctuations when ensemble averaged data were available from the field experiments. Differences observed between measured and predicted concentrations and concentration fluctuations, in the case of laterally displaced sources, were mainly attributed to the specificities of the experimental cases, such as the interaction of a laterally displaced plume with an obstacle, and to the variability observed in the field. The effect of this variability is indicated by the difference between the predicted-to-observed ratios of ensemble-averaged centreline values for propane and the respective ratios from the single ammonia experiment with co-located gas sources, the latter being higher by upto 30% for concentrations and 70% for concentration fluctuations. Using the computational tool it was shown that, for a laterally displaced source, a change of 5° in the mean wind direction can lead up to a 100% variation in the measured concentrations.     

Risk assessment approach for untreated wastewater using the QUAL2E water quality model

This paper presents a novel approach for assessing the risk of consumer product ingredients in surface waters that receive untreated wastewater. The approach utilizes the water quality simulation model QUAL2E for predicting the impact caused by conventional pollutants, as well as the exposure concentration of consumer product ingredients. This approach invokes an impact zone concept whereby the receiving water can be thought of as a natural wastewater treatment system. After the river has recovered via self-purification, the ecosystem is then assessed by traditional risk assessment methods. This approach was validated using data collected from the Balatuin River, which is located in the Philippines. Results from this study support the use of QUAL2E for assessing the risk of consumer product ingredients in riverine systems receiving untreated wastewater.     

Progestagens for human use, exposure and hazard assessment for the aquatic environment

Little information is available on the environmental occurrence and ecotoxicological effects of pharmaceutical gestagens released in the aquatic environment. Since eighteen different gestagens were found to be used in France, preliminary exposure and hazard assessment were done. Predicted environmental concentrations (PECs) suggest that if parent gestagens are expected to be found in the ng l⁻¹ range, some active metabolites could be present at higher concentrations, although limited data on metabolism and environmental fate limit the relevance of PECs. The biological effects are not expected to be restricted to progestagenic activity. Both anti-androgenic activity (mainly for cyproterone acetate, chlormadinone acetate and their metabolites) and estrogenic activity (mainly for reduced metabolites of levonorgestrel and norethisterone) should also occur. All these molecules are likely to have a cumulative effect among themselves or with other xenoestrogens. Studies on occurrence, toxicity and degradation time are therefore needed for several of these compounds.     

Evaluation of the exposure methodology for risk-benefit assessment of seafood consumption

This study evaluated the methodology of using existing, international data to calculate the intake of nutrients and contaminants via seafood consumption on a national level. This was done by combining French seafood consumption data with two different datasets. The results showed that a significant correlation was found between the results obtained by using different data sets and that a high percentage of the population was classified in the same category (above or below the intake reference values). As such, the general conclusion that can be drawn from the results: 'whether a part of the population does exceed the toxicological reference values for certain contaminants and whether a part of the population does not reach the recommended intake for certain nutrients' remains the same for the two approaches. Therefore, it can be concluded that the existing, international probability distributions are useful when aiming to perform a cost-effective risk benefit evaluation of seafood consumption on national or regional level. When this evaluation does indicate that more detailed results are needed because a certain health risk exists, it can be decided that it is worth to spend more time and money for the analyses of national samples in order to collect more detailed results.     

Toxicity and biodegradation of the LAS surfactant 1-(p-sulfophenyl)nonane in presence of the ascidian Styela plicata

The main objective of this study, within development of engineering solutions for coastal areas depuration, was to establish the role of the benthic macro-organisms in the biodegradation of the detergents in marine environment and to estimate the toxicity of these substances for a particular marine species: the ascidian Styela plicata. The experimental studies undertaken in aquarium with seawater enriched in a pure lynear alkylbenzene sulfonate (LAS), the 1-(p-sulfophenyl)nonane (1C9-LAS), showed that the degradation was two times more fast in presence of the S. plicata, than of the only marine bacteria. The toxicity of this pollutant was also determined. This study demonstrates that the ascidia S. plicata can be a potential biomediator for the surfactant 1C9-LAS, and it can be used to design a pilot project, to bioremediate harbours and the coastal areas interested from the urban pollution.     

Effect of mixed liquor suspended solids concentration on the biodegradation of nitrilotriacetic acid in the activated sludge process

The biodegradation of nitrilotriacetic acid in laboratory simulations of the activated sludge process has been studied at two different concentrations of mixed liquor suspended solids. Responses to changes in the influent nitrilotriacetic acid concentration such as those which might be associated with a “wash day” have been examined.     

利用AQUATOX模型评价淀山湖二氯甲烷生态风险

淀山湖地处上海的饮用水源地,水体中有机污染物的生态风险逐渐引起人们的重视。淀山湖水质监测结果显示,淀山湖中的挥发性有机物以二氯甲烷为主。应用美国环境保护署的AQUATOX模型对淀山湖水体中二氯甲烷进行模拟,并进行生态风险评价,旨在构建基于AQUATOX模型的水环境中有机物浓度模拟方法及风险评价的研究体系。结果显示,淀山湖中的二氯甲烷尚处于安全范围,但是需要加强观测,避免高风险的发生。     

Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added ¹³C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass.     

Priority assessment of toxic substances in life cycle assessment. Part I: calculation of toxicity potentials for 181 substances with the nested multi-media fate, exposure and effects model USES-LCA

Toxicity potentials are standard values used in life cycle assessment (LCA) to enable a comparison of toxic impacts between substances. In most cases, toxicity potentials are calculated with multi-media fate models. Until now, unrealistic system settings were used for these calculations. The present paper outlines an improved model to calculate toxicity potentials: the global nested multi-media fate, exposure and effects model USES-LCA. It is based on the Uniform System for the Evaluation of Substances 2.0 (USES 2.0). USES-LCA was used to calculate for 181 substances toxicity potentials for the six impact categories freshwater aquatic ecotoxicity, marine aquatic ecotoxicity, freshwater sediment ecotoxicity, marine sediment ecotoxicity, terrestrial ecotoxicity and human toxicity, after initial emission to the compartments air, freshwater, seawater, industrial soil and agricultural soil, respectively. Differences of several orders of magnitude were found between the new toxicity potentials and those calculated previously.     

西安市PM2.5污染特征及其估测模型

为了研究大气中PM2.5污染特征以及其随时间变化规律,基于西安市2013年1月—2014年4月间SO2、NO2、CO、O3、日最高温度(Tmax)、日最低温度(Tmin)、PM2.5、PM10等因素的监测数据.运用统计学原理和多元回归分析方法,分析了PM2.5的污染特征及相关因素对其产生的贡献度,进一步建立了四季的最优多元回归模型.研究结果表明,西安市年平均质量浓度124.9 μg/m3,四季的平均污染浓度从大到小依次为冬、春、秋、夏;春夏两季贡献较大的为SO2、CO;秋冬两季贡献较大的为NO2、CO;最终建立的模型的相关系数较高,模型很好地拟合了冬春两季PM2.5变化趋势,能较准确地反映了西安市PM2.5的污染特征,具有一定的理论和实用价值.     

Shifted power-law relationship between NO2 concentration and the distance from a highway: A new dispersion model based on the wind profile model

In this paper, a shifted power-law model, based on the wind profile model, had been supposed to simulate concentration gradient of nitrogen dioxide (NO₂) with distance from a highway. Field experiments were performed for NO₂ gradients from a highway in Shanghai by using passive samplers. The shifted power-law model was fitted well with experimental results of field experiments both in this study and in the literature. The results not only verified the validity of shifted power-law relationship between NO₂ concentration and the distance from a highway, but also partially demonstrated that there were some significant similarities between wind profile and air pollutants concentration profile near highway. With known concentration of chosen reference point and appropriate value of the parameter k, the model could be practically applied for predicting the NO₂ distributions near a highway. The methods of determining the parameter k were also discussed for further detailed studies.     

垃圾渗滤液有机物浓度预测模型的建立及应用

在分析垃圾渗滤液有机物浓度变化规律的基础上,建立垃圾渗滤液有机物浓度预测模型,并通过模拟填埋实验求出模型参数.该模型预测值与实测值之间具有接近90%的相关性,表明模型预测值基本上反映了实测值的变化规律.同时,将此模型应用到广西南宁市城南垃圾填埋场坝下区,对坝下区垃圾渗滤液有机物浓度变化规律进行预测.结果表明,坝下区垃圾...     

Comparison of two estimation methods for surface area concentration using number concentration and mass concentration of combustion-related ultrafine particles

Recent research has suggested that the adverse health effects caused by nanoparticles are associated with their surface area (SA) concentrations. In this study, SA was estimated in two ways using number and mass concentrations and compared with SA (SA_meas) measured using a diffusion charger (DC). Aerosol measurements were made twice: once starting in October 2002 and again starting in December 2002 in Mysore, India in residences that used kerosene or liquefied petroleum gas (LPG) for cooking. Mass, number, and SA concentrations and size distributions by number were measured in each residence. The first estimation method (SA_PSD) used the size distribution by number to estimate SA. The second method (SA_INV) used a simple inversion scheme that incorporated number and mass concentrations while assuming a lognormal size distribution with a known geometrical standard deviation. SA_PSD was, on average, 2.4 times greater (range = 1.6–3.4) than SA_meas while SA_INV was, on average, 6.0 times greater (range = 4.6–7.7) than SA_meas. The logarithms of SA_PSD and SA_INV were found to be statistically significant predictors of the logarithm of SA_meas. The study showed that particle number and mass concentration measurements can be used to estimate SA with a correction factor that ranges between 2 and 6.     

Modeling of temporal variations of vertical concentration profile of 7Be in the atmosphere

Study of the vertical concentration profile and of the deposition of cosmogenic radionuclides provides information on the vertical transport in the stratosphere and troposphere and the processes of scavenging of aerosol particles by precipitation. Information on the distribution of atmospheric aerosols is important for the understanding of the physical processes relating to the studies in weather climate, air pollution, and aerosol physics. In this work the one-dimensional steady-state model of vertical concentration profile was established and the values of turbulent diffusion coefficient and scavenging coefficient determined by model using experimental data of the ⁷Be monthly average atmospheric activity concentrations and monthly deposition fluxes in Bratislava are presented. The temporal variations of the vertical distribution profiles of ⁷Be for each month are also calculated.     

Two-phase partitioning bioreactor for the biodegradation of high concentrations of pentachlorophenol using Sphingobium chlorophenolicum DSM 8671

An organic-aqueous two-liquid-phase partitioning system was developed to degrade high concentrations of pentachlorophenol (PCP). Dioctyl sebacate was selected among 12 non-aqueous phases as the most suitable solvent to control the delivery of PCP to the aqueous phase for being non-biodegradable and biocompatible. In shake-flask experiments, the two-phase system was able to support the removal of 1g PCP l(-1) of total liquid phase. The performance of the two-liquid phase partitioning system (TLPPS) in shake-flask was evaluated under different conditions. At the initial biomass concentrations of 7, 25, and 58 mg dry weight l(-1), the volumetric removal rates of PCP obtained were 25.7+/-0.5, 32.1+/-0.1, and 39.3+/-2.9 mg PCP l(-1)h(-1), respectively. Higher performance was observed at lower organic-aqueous phase ratios (16% and 28%) than higher ones (37% and 44%). In a 2-l TLPPS, the degradation of 10 g PCP was completed in less than 100 h at a total volumetric rate of 142 mg l(-1) h(-1). Kinetics study using Monod model showed that compared to monophasic systems, the biphasic system significantly enhanced the maximum specific growth rate and PCP removal rate. Results of this biphasic system showed no accumulation of unknown by-product(s) which has been reported for physical-pretreatment or high-performance biphasic systems of PCP degradation.