Surface stormwater hazard assessment in steep urban areas. Case of the city of Mendoza,Argentina

The current paper focusses on the hazard assessment associated with urban runoff on streets. A review of the existing criteria to evaluate such a hazard is made. Two new criteria based on theoretical analysis of the water's force acting on a static pedestrian are presented: no slipping criterion and stability to tilt criterion. According to these criteria, either a maximum depth, or a maximum velocity or some relation between depths and velocities should be fulfilled in order to guarantee the pedestrian's and driver's safety in the case of medium to large storms. A one-dimensional numerical model is used to solve the urban storm runoff within a street network. This model is applied to an urban watershed of the city of Mendoza (Argentina), obtaining the runoff values belonging to return periods of 5, 10 and 25 years. The results are evaluated bearing in mind four hazard criteria. In conclusion, the numerical model is shown to be a useful tool in relation to the application of the hazards criteria. It is also conclude that an effort should be made to determine specific hazard criteria based on experimental data.     

Characterization of roadway stormwater system residuals for reuse and disposal options

The chemical characterization of sediments accumulated in catch basins and stormwater ponds provides important information for assessing risks associated with management of these residuals upon removal of accumulated deposits in stormwater systems. In this study, over a period of 15 months, more than 150 residual samples were collected from 77 catch basin units and 22 stormwater ponds from 16 municipalities throughout the state of Florida. Concentrations (mg/kg) of metals and metalloids (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) and trace organics (volatile organics, semi-volatile organics, herbicides, and pesticides) in the sediments were measured. In addition, the synthetic precipitation leaching procedure (SPLP) was utilized to evaluate pollutant leachability risk for a subset of the samples collected. Measured pollutant concentrations were compared to corresponding risk-based guidelines in Florida (i.e., Florida soil cleanup target levels) to assess potential human health risks of beneficial use of these residuals through land application. Leached concentrations were compared to risk-based water quality guidelines (i.e., Florida groundwater cleanup target levels) to examine the potential for groundwater contamination. Although several metals (arsenic, barium, chromium, copper, nickel, lead, and zinc) were routinely detected in the catch basin and stormwater pond sediments, their concentrations were generally lower than the Florida's risk-based cleanup target levels for soils. A small number of organochlorine compounds (e.g., 4,4′-DDE, 4,4′-DDT) were detected, but only in a limited number of the samples (less than 10%); leaching of trace organic pollutants above the Florida risk-based groundwater thresholds was rare. The results suggest that when land-applied or beneficially used, these residuals are not expected to pose a significant threat to human health or the environment and the results of this research will provide stormwater managers and environmental management authorities with a useful resource to examine proper disposal and beneficial use of catch basin and stormwater pond sediments.     

An updated weight of evidence approach to the aquatic hazard assessment of Bisphenol A and the derivation a new predicted no effect concentration (Pnec) using a non-parametric methodology

An aquatic hazard assessment establishes a derived predicted no effect concentration (PNEC) below which it is assumed that aquatic organisms will not suffer adverse effects from exposure to a chemical. An aquatic hazard assessment of the endocrine disruptor Bisphenol A [BPA; 2, 2-bis (4-hydroxyphenyl) propane] was conducted using a weight of evidence approach, using the ecotoxicological endpoints of survival, growth and development and reproduction. New evidence has emerged that suggests that the aquatic system may not be sufficiently protected from adverse effects of BPA exposure at the current PNEC value of 100 μg/L. It is with this background that; 1) An aquatic hazard assessment for BPA using a weight of evidence approach, was conducted, 2) A PNEC value was derived using a non parametric hazardous concentration for 5% of the specie (HC₅) approach and, 3) The derived BPA hazard assessment values were compared to aquatic environmental concentrations for BPA to determine, sufficient protectiveness from BPA exposure for aquatic species. A total of 61 studies yielded 94 no observed effect concentration (NOEC) and a toxicity dataset, which suggests that the aquatic effects of mortality, growth and development and reproduction are most likely to occur between the concentrations of 0.0483 μg/L and 2280 μg/L. This finding is within the range for aquatic adverse estrogenic effects reported in the literature. A PNEC of 0.06 μg/L was calculated. The 95% confidence interval was found to be (0.02, 3.40) μg/L. Thus, using the weight of evidence approach based on repeated measurements of these endpoints, the results indicate that currently observed BPA concentrations in surface waters exceed this newly derived PNEC value of 0.06 μg/L. This indicates that some aquatic receptors may be at risk for adverse effects on survival, growth and development and reproduction from BPA exposure at environmentally relevant concentrations.     

Uncertainty in urban stormwater quality modelling: The influence of likelihood measure formulation in the GLUE methodology

In the last years, the attention on integrated analysis of sewer networks, wastewater treatment plants and receiving waters has been growing. However, the common lack of data in the urban water-quality field and the incomplete knowledge regarding the interpretation of the main phenomena taking part in integrated urban water systems draw attention to the necessity of evaluating the reliability of model results. Uncertainty analysis can provide useful hints and information regarding the best model approach to be used by assessing its degrees of significance and reliability. Few studies deal with uncertainty assessment in the integrated urban-drainage field. In order to fill this gap, there has been a general trend towards transferring the knowledge and the methodologies from other fields. In this respect, the Generalised Likelihood Uncertainty Evaluation (GLUE) methodology, which is widely applied in the field of hydrology, can be a possible candidate for providing a solution to the above problem. However, the methodology relies on several user-defined hypotheses in the selection of a specific formulation of the likelihood measure. This paper presents a survey aimed at evaluating the influence of the likelihood measure formulation in the assessment of uncertainty in integrated urban-drainage modelling. To accomplish this objective, a home-made integrated urban-drainage model was applied to the Savena case study (Bologna, IT). In particular, the integrated urban-drainage model uncertainty was evaluated employing different likelihood measures. The results demonstrate that the subjective selection of the likelihood measure greatly affects the GLUE uncertainty analysis.     

A methodology for assessing geotechnical hazards for TBM tunnelling—illustrated by the Athens Metro, Greece

Unexpected ground conditions have always been a major problem for the tunnelling industry. As demand for the development of new underground structures, regardless of the ground conditions, has increased, safety and risk considerations have become even more important. The methodology presented in this paper aims at the identification of risk-prone areas, incorporating, at the same time, the uncertainty of ground conditions. It is focused on TBM tunnelling and can be implemented in the early stages of the project. The methodology assesses the hazards by introducing the concept of a vulnerability index, which is based on the principles of rock engineering systems, to identify the weighting of the parameters, and on probabilistic modelling to address the uncertainty in the parameters’ values. The proposed model is illustrated via the Athens Metro case study, used also for validating its performance under actual construction conditions.     

Development of particle-based biofilms for degradation of xenobiotic organic compounds

The aim of the experiments performed in this work was to develop a biofilm airlift suspension (BAS) process for the degradation of a mixture of organic sulfonates contained in the infiltration water from a contaminated site. To achieve this goal, active biomass growing on the contaminating xenobiotic organics as the sole source of carbon was obtained by enriching a mixed microbial culture sampled from an activated sludge treatment plant. After kinetic characterisation, the enriched culture was inoculated in the BAS reactor, where it colonised carrier particles and formed stable and uniform biofilms. In spite of the slow growth and degradation kinetics (mu(max)=0.014 h(-1)), due to high biomass concentration (up to 12 g(VS)L(-1)) a high rate process was performed in the BAS reactor, achieving a degradation capacity of 8.7 kg(COD)m(-3)d(-1), with an overall degradation efficiency of 70% based on COD measurements.     

Modelling the fate of organic micropollutants in stormwater ponds

Urban water managers need to estimate the potential removal of organic micropollutants (MP) in stormwater treatment systems to support MP pollution control strategies. This study documents how the potential removal of organic MP in stormwater treatment systems can be quantified by using multimedia models. The fate of four different MP in a stormwater retention pond was simulated by applying two steady-state multimedia fate models (EPI Suite and SimpleBox) commonly applied in chemical risk assessment and a dynamic multimedia fate model (Stormwater Treatment Unit Model for Micro Pollutants — STUMP). The four simulated organic stormwater MP (iodopropynyl butylcarbamate — IPBC, benzene, glyphosate and pyrene) were selected according to their different urban sources and environmental fate. This ensures that the results can be extended to other relevant stormwater pollutants. All three models use substance inherent properties to calculate MP fate but differ in their ability to represent the small physical scale and high temporal variability of stormwater treatment systems. Therefore the three models generate different results. A Global Sensitivity Analysis (GSA) highlighted that settling/resuspension of particulate matter was the most sensitive process for the dynamic model. The uncertainty of the estimated MP fluxes can be reduced by calibrating the dynamic model against total suspended solids data. This reduction in uncertainty was more significant for the substances with strong tendency to sorb, i.e. glyphosate and pyrene and less significant for substances with a smaller tendency to sorb, i.e. IPBC and benzene. The results provide support to the elaboration of MP pollution control strategies by limiting the need for extensive and complex monitoring campaigns targeting the wide range of specific organic MP found in stormwater runoff.     

Sonochemical degradation of chlorinated organic compounds, phenolic compounds and organic dyes - A review

Sonochemical processes have been widely used in chemistry and chemical engineering field. Recently, these processes have found new applications in the environmental field, because of advantages in terms of operational simplicity, secondary pollutant formation and safety. Several studies have reported on sonochemical degradation of organic compounds that are toxic in nature. The objective of this review was to identify and examine some of the studies on sonochmical degradation of chlorinated organic compounds, phenolic compounds and organic dyes. This review also examines the basic theory of sonochemical reactions and the use of sonochemical reactors for environmental applications.     

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 μg/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.     

A glance into aluminum toxicity and resistance in plants

Aluminum toxicity is an important stress factor for plants in acidic environments. During the last decade considerable advances have been made in both techniques to assess the potentially toxic Al species in environmental samples, and knowledge about the mechanisms of Al toxicity and resistance in plants. After a short introduction on Al risk assessment, this review aims to give an up-to-date glance into current developments in the field of Al toxicity and resistance in plants, also providing sufficient background information for non-specialists in aluminum research. Special emphasis is paid to root growth and development as primary targets for Al toxicity. Mechanisms of exclusion of Al from sensitive root tips, as well as tolerance of high Al tissue levels are considered.     

Measuring the saturation limit of low-volatility organic compounds in soils: implications for estimates of dermal absorption

Estimating dermal absorption from contaminated soils typically requires extrapolations from measurements obtained on soils artificially contaminated at much larger concentrations. Such extrapolations should be constrained by the fact that maximum absorption will occur for the largest possible concentration of chemical on the soil without neat chemical being present; i.e., at the soil saturation limit (S_soil). Saturation limits of two low-volatility model compounds (4-cyanophenol and methyl paraben) were determined on the 38-63 μm sieve fraction of four soils with different fractions of organic carbon (f_oc = 0.015-0.45) and specific surface areas (σ_soil = 4-34 m² g^− 1) using two methods: equilibrium uptake into silicone rubber membranes and differential scanning calorimetry. Except for Pahokee peat, which had the largest f_oc, a model assuming contributions from both surface adsorption and organic carbon absorption provided excellent predictions of S_soil. In all soils, the surface saturation concentration of both chemicals was estimated at 2.2 mg m^− 2. The saturation concentration of 4-cyanophenol in the soil organic carbon was 1.7-fold higher than methyl paraben, which is consistent with the estimated solubility limits of these two chemicals in octanol.     

我国沿海危化品运输事故分析及危险源辨识

为了探究沿海地区危险化学品道路运输事故特征,辨识相关风险因子,以2016-2020年我国沿海地区发生的362起危险化学品运输事故为例,从事故发生的时间分布、省份分布、危险化学品类别及形态、事故类型、事故原因等多方面进行统计分析.结果表明:近5年来,我国危险化学品运输事故逐年减少.每年的5月、9月、12月,每天的清晨是事...     

Mineralization of some natural refractory organic compounds by biodegradation and ozonation

The objective of this study was to explore the extent of mineralization, reduction in color and reduction of COD of gallic acid, tannin and lignin by ozonation and a combination of aerobic biodegradation and ozonation. Ozonation of pure aliquots (phase I experiments) resulted in the decline in TOC, COD, COD/TOC ratio, UV absorbance at 280 nm and color of the three model compounds investigated, with COD removals of greater than 80% and high removals (>90%) of UV absorbance at 280 nm and color observed in all cases at an ozone dose of 6 mg ozone/mg initial TOC or higher. Aerobic biodegradation of pure gallic acid, tannin and lignin aliquots resulted in COD decline of approximately 36-38%. Subsequent ozonation (phase II experiments) resulted in further decline in TOC, COD, COD/TOC ratio, and increase in UV absorbance at 280 nm and color removals. COD and TOC removals comparable to phase I experiments were obtained with 30-40% lower ozone absorption in phase II experiments. The biodegradation step was quite effective in removing specific UV absorbance at 280 nm, with up to 75% removal observed. Subsequent ozonation increased overall specific UV absorbance at 280 nm to greater than 90%.     

Ozone decomposition of hazardous chemical substance in organic solvents

Performance on the ozonation of hazardous chemicals in non-aqueous solutions, i.e. organic solvents, was studied in comparison with those in water. The specific conclusions obtained from this study are as follows: the rate of decomposition and the specific amount of decomposition per ozone consumption for orange II were higher in organic solvents like acetic acid, acetone, ter-butyl alcohol than in distilled water. The rates of trichloroethylene decomposition in organic solvents like acetic acid, acetone, and ethyl acetate were also higher than those in distilled water.     

Ecological vulnerability in risk assessment — A review and perspectives

This paper reviews the application of ecological vulnerability analysis in risk assessment and describes new developments in methodology. For generic non-site-specific assessments (e.g. for the requirements of most European directives on dangerous chemicals) risk is characterised just on the basis of the ratio between an effect indicator and an exposure indicator. However, when the actual risk for a specific ecosystem is desired, the concept of ecological vulnerability may be more appropriate. This calls for a change in thinking, from sensitivity at the organism level to vulnerability at higher organization levels, and thus forms the link from laboratory toxicology to field effects at population, community or ecosystem level. To do so, biological and ecological characteristics of the ecosystems under concern are needed to estimate the ecological vulnerability.In this review we describe different vulnerability analysis methods developed for populations (of a single species), communities (consisting of different populations of species) and ecosystems (community and habitat combined). We also give some examples of methods developed for socio-ecological systems. Aspects that all methods share are the use of expert judgment, the input of stakeholders, ranking and mapping of the results, and the qualitative nature of the results.A new general framework is presented to guide future ecological vulnerability analysis. This framework can be used as part of ecological risk assessment, but also in risk management. We conclude that the further quantification of ecological vulnerability is a valuable contribution to vulnerability assessment.     

Ecological risk assessment of lead contamination at rifle and pistol ranges using techniques to account for site characteristics

Spent ammunition at outdoor rifle and pistol (RP) firing ranges creates a characteristic pattern of contamination, whereby small areas surrounding backstop berms exhibit extremely high soil lead (Pb) concentrations. We characterized sources, pathways and uncertainty in contaminant accumulation for receptors at two RP ranges in southeastern Ontario. Based on these results, we performed risk calculations using kriging to estimate risk across "worst-case" species foraging ranges. Range-normalized hazard quotients (RNHQ) were then calculated to estimate risk across each receptor's foraging range. Monte Carlo simulation was used to provide +2 standard deviation (SD) risk estimates, in order to account for uncertainty in risk parameters. The American robin was found to be most at risk (RNHQ=4.10; +2SD=9.24), followed by the short-tailed shrew (RNHQ=0.113; +2SD=0.243) and the eastern cottontail (RNHQ=0.109; +2SD=0.703). Elevated risk for the American robin and short-tailed shrew was due to their small foraging ranges and habit of eating earthworms, which bioaccumulate Pb. Elevated risk for the eastern cottontail was due to vegetation accumulating Pb to levels that were considerably higher than conventional bioaccumulation models would indicate. The results of this study clearly emphasize the importance of specific characteristics of RP ranges, such as contamination patterns, dust accumulation on plant tissues, and contaminant bioaccessibility. These characteristics should be accounted for, not only in performing risk assessments, but also in choosing remedial options and in routine management practices.     

Bacteria enclosure between silica-coated membranes for the degradation of organic compounds in contaminated water

A non-conventional technique is proposed for the enclosure of either pure bacterial cultures or entire biocoenoses, for a possible utilization in the treatment of contaminated water. Biological components have been enclosed between polyester membranes coated by silica films consisting of: (a) SiO2 and nitrocellulose, (b) SiO2, ZnS crystals and nitrocellulose, (c) SiO2, TiO2 crystals and nitrocellulose, (d) SiO2, ZnS and TiO2 crystals and nitrocellulose. Morphological, structural and mechanical features of membranes were investigated by means of optical and electron microscopy, mercury porosimetry and wear resistance tests. Degradation kinetics have been finally studied by dipping the entrapped biomass into aqueous solutions of three different model organic compounds (alpha-d-glucose, ethyl alcohol and peptone). Results are very promising: in fact, no metabolic inhibition mechanisms of microorganisms have been evidenced. The porosity of the system allows mass transfer through the membranes, hence bacteria can grow and degrade pollutants. Besides, by this system, cells are constrained, avoiding they to spread across the retainment scaffold.     

A quantitative property‐property relationship for the internal diffusion coefficients of organic compounds in solid materials

Indoor releases of organic chemicals encapsulated in solid materials are major contributors to human exposures and are directly related to the internal diffusion coefficient in solid materials. Existing correlations to estimate the diffusion coefficient are only valid for a limited number of chemical‐material combinations. This paper develops and evaluates a quantitative property‐property relationship (QPPR) to predict diffusion coefficients for a wide range of organic chemicals and materials. We first compiled a training dataset of 1103 measured diffusion coefficients for 158 chemicals in 32 consolidated material types. Following a detailed analysis of the temperature influence, we developed a multiple linear regression model to predict diffusion coefficients as a function of chemical molecular weight (MW), temperature, and material type (adjusted R² of .93). The internal validations showed the model to be robust, stable and not a result of chance correlation. The external validation against two separate prediction datasets demonstrated the model has good predicting ability within its applicability domain (>.8), namely MW between 30 and 1178 g/mol and temperature between 4 and 180°C. By covering a much wider range of organic chemicals and materials, this QPPR facilitates high‐throughput estimates of human exposures for chemicals encapsulated in solid materials.