Contaminant Concentration Levels Research Articles

Concentration levels of atmospheric contaminants in Brazilian cities measured by passive sampling

Measurements of air pollutants were made using passive sampling in Brazilian urban centers. The levels of SO2 and NO2 exceeded the WHO recommendations in São Paulo (SP), Londrina and Rio de Janeiro. Formaldehyde concentrations exceeded international recommendations in all urban centers and benzene concentrations exceeded 1.7 μg m−3, level associated with the probability of leukemia, according to the WHO. Sewage discharge in the Pinheiros River - SP and in Lake Pampulha - BH contributed to higher levels of H2S and NH3 in these urban centers. The BH atmosphere was also influenced by emissions from landfills. Organic and inorganic acids contributed similarly to atmospheric acidity. 71% of the calculated ratios between concentrations of formic and acetic acids were < 1, demonstrating the predominant influence of vehicle emissions on the atmospheric levels of these acids. Multivariate analysis showed that VOCs and organic acids are more influenced by temperature and solar radiation. The stronger direct relationship of NOx was with wind direction, showing competition between local emission and photochemical aging of these compounds brought from other locations. On a global scale, studies of this type are necessary and important to increase the accuracy of exposure estimates in different places where people live.

Extreme exposure of fluoride and arsenic contamination in shallow coastal aquifers of the Ganges delta, transboundary of the Indo-Bangladesh region

Globally, shallow aquifer groundwater (GW) has been severely affected in recent decades for both geogenic and anthropogenic reasons. The hydro-geochemical characteristics of the GW change inconsistently with the addition of unwanted inorganic trace elements into the GW aquifer of the Indo-Bangladesh delta region (IBDR), such as arsenic (As) along with fluoride (F−) contamination. Contaminated GW can have a negative impact on drinking water supplies and agricultural output. GW pollution can have serious adverse effects on the environment and human health. Thus, the GW quality of this region is deteriorating progressively, and human health threatening by various life-threatening disorders. Hence, the current study concentrated on the GW quality evaluation and prediction of possible health issues in the IBDR due to elevated contamination of As along with F− within GW aquifers by considering sixteen causative. Field survey-based statistical methods such as entropy quality index (EWQI) combined with health risk index (HRI) was implemented for evaluating the As and F− sensitivity with the help of correlation testing and principal component analysis. The study's outcome explains that a substantial portion of the IBDR has been vastly experiencing inferior GW quality, environmental issues, and health-related problems in dry and wet seasons, correspondingly for As and F− exposure. Piper diagram verified the suitability of water that almost 55% of GW across the study area’s aquifers are unfit for drinking as well as cultivation of crops. Sensitivity analysis and the Monte Carlo simulation method were also applied to assess the contaminant's concentration level and probable health risk appraisal. The present study concludes that the elevated exposure of As and F− pollution has to be monitored regularly and prevent unwanted GW contamination through implementing sustainable approaches and policies to fulfil the sustainable development goal 6 (SDG-6) till 2030, ensuring the most basic human right of clean, safe, and hygienic water.

Impact of air pollution on groundwater contamination through water reservoir

ABSTRACT In this article, an incisive analysis had been carried out to investigate the impact of air pollution on groundwater through a water reservoir. The primary objective of the present work was to develop a mathematical model that shows the direct impact of air pollution on groundwater contamination. The advection-dispersion equation (ADE) was considered to model the contaminant transport through the different media. Due to its inherent complexities, contaminant transport through the different domains was often difficult to model. To overcome it, the simple solution was to consider different velocities and dispersion for different domains. It was considered that the air zone was directly connected with the groundwater through a large water body. Initially, water body and aquifer had been considered contaminant free along with the flux type boundary condition at the semi-infinite part of the boundary. The model had been solved analytically using Laplace transformations. The current study demonstrates that depending upon the length of the medium the impact of contaminant would vary significantly. The air pollution source height had a direct impact on the contaminant concentration level in the aquifer aquitard system. The current study also illustrates that around 25% of air pollutants were induced in the groundwater.

Occurrence of organic contaminants bonded to the particulate matter from outdoor air influenced by industrial activities.

This paper discusses the occurrence of organic contaminants bonded to particulate matter (PM) in ambient air. We describe the presence and concentration levels of contaminants mainly reported in atmospheres close to factories or at locations influenced by them, and the relationship between factory emissions and the type of organic contaminants found in PM samples from the surrounding air. Many organic contaminants have been found in these types of samples, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). Their sources, fates and distributions in the ambient atmosphere are therefore well known. However, in addition to these most studied compounds, others are also of concern nowadays due to their detection and toxic effects on the environment. The continuous updating of regulations on these contaminants and the appearance of new air pollutants make it important to be aware of their occurrence. This will help to either establish new guidelines for the newer contaminants or reassess existing limitations for known ones. Moreover, if we know their occurrence, we can analyse their sources, destinations and distributions in the outdoor air.

Where you drink water: An assessment of the Tennessee, USA public water supply.

Monitoring drinking water quality is essential to protect people's health and wellbeing. In the United States, the Safe Drinking Water Information System (SDWIS) database records the occurrence of a drinking water violation regulation in public water systems. A notable shortcoming of SDWIS is the lack of the contaminant concentration level about the allowable maximum contaminant threshold. In this study, we take advantage of both the SDWIS violation database and the contaminants sampling database at the state level to examine the drinking water quality of all kinds of drinking water systems in detail. We obtained sampling data (i.e., the concentration level of contaminants) of public water systems (PWSs) in Tennessee and explored the statistical distribution of contaminant concentration data in relation to the enforceable maximum regulatory contaminant level). We use both SDWIS violation records and actual concentrations of contaminants from the sampling data to study the factors that influence the drinking water quality of PWSs. We find that different types of violations were more frequent in (1) specific geological regions, (2) counties with PWSs that serve a larger population (10,000 to 100,000 people), and (3) places with abundant surface water, such as near a lake or major river. Additionally, the distribution of measured concentrations for many contaminants was not smooth but was punctuated by discontinuities at selected levels, such as at 50% of the maximum contaminant level. Such anomalies in the sampling data do not indicate violations, but more investigation is needed to determine the reasons behind the punctuated changes.

Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania

Geogenic contamination of groundwater is frequently associated with gold mining activities and related to drinking water quality problems worldwide. In Tanzania, elevated levels of trace elements (TEs) have been reported in drinking water sources within the Lake Victoria Basin, posing a serious health risk to communities. The present study aims to assess the groundwater quality with a focus on the concentration levels of geogenic contaminants in groundwater around the Lake Victoria goldfields in Geita and Mara districts. The water samples were collected from community drinking water sources and were analysed for physiochemical parameters (pH, EC, Eh), major ions, and trace elements. The analysed major ions included Na+, K+, Ca2+, Mg2+, SO42−, HCO3− and Cl− whereas the trace elements were As, Al, Li, Ba, B, Ti, V, U, Zr, Sr, Si, Mn Mo, Fe, Ni, Zn, Cr, Pb, Cd, and V. The present study revealed that the concentration levels of the major ions were mostly within the World Health Organization (WHO) drinking water standards in the following order of their relative abundance; for cations, Ca2+∼Na+>Mg2+>K+ and for anions was HCO3− > SO42− > NO3−, Cl− > PO43−. Statistical and geochemical modelling software such as ‘R Studio’, IBM SPSS, geochemical workbench, visual MINTEQ were used to understand the groundwater chemistry and evaluate its suitability for drinking purpose. The concentration of As in groundwater sources varies between below detection limit (bdl) and 300 μg/L, with highest levels in streams followed by shallow wells and boreholes. In approximately 48% of the analysed samples, As concentration exceeded the WHO drinking water guideline and Tanzania Bureau of Standards (TBS) guideline for drinking water value of 10 μg/L. The concentration of the analyzed TEs and mean values of physicochemical parameters were below the guideline limits based on WHO and TBS standards. The Canadian Council of Ministries of the Environment Water Quality Index (CCME WQI) shows that the overall water quality is acceptable with minimum threats of deviation from natural conditions. We recommend further geochemical exploration and the periodic risk assessment of groundwater in mining areas where high levels of As were recorded.

Increased heavy metal concentrations in the soils near electric power generators in Samarra city (Iraq)

Purpose. To determine the concentration levels of various heavy metals and carbon in the soils of four Samarra City areas that are close to pollution sources (electric power generators). Methodology. A pollution source is sampled at a distance of 5, 10, 15, and 20 meters. The concentrations of iron (Fe), lead (Pb), copper (Cu), cadmium (Cd) metals, as well as carbon, are then determined. Findings. It has been determined that the iron and copper concentrations are within the permissible limits prescribed by the United States Environmental Protection Agency. However, the soils contaminated with cadmium and lead in concentration exceed the permissible limits. The metal concentrations increase with distance from the source. The metal concentration is low at a distance of 5 m from the pollution source, then it increases at a greater distance. Moreover, metals are found in soils at a distance of 10 m, then their concentration further increases at a distance up to 20 m. Concentrations of metal and carbon at a distance of 20m are the highest. Originality. This study determines the concentration level of heavy metal contaminants, as well as the impact of electric power generating waste on the metropolis. According to the study, the concentration of these components increases around electric power producers. Practical value. The concentrations of heavy metals in soils increase as the distance from the source of pollution increases.

Assessment of Concentration Levels of Contaminants in Groundwater of the Soutpansberg Region, Limpopo Province, South Africa

Groundwater contributions towards improved food security and human health depend on the level of contaminants in groundwater resources. Many people in rural areas use groundwater for drinking purposes without treatment and knowledge of contaminant levels in such waters, owing to parachute research in which research outputs are not shared with communities. This study argues that parachute research exposes groundwater users to health hazards and threatens the food security of communities. Concentration levels of contaminants were measured to ascertain suitability of groundwater for drinking and irrigation purposes. A total of 124 groundwater quality samples from 12 boreholes and 2 springs with physiochemical data from 1995 to 2017 were assessed. This study found high concentration levels of contaminants, such as F−, NO3−, Cl−, and total dissolved solids, in certain parts of the studied area. In general, groundwater was deemed suitable for drinking purposes in most parts of the studied area. Combined calculated values of sodium adsorption ratios, Na%, magnesium hazards, the permeability index, residual sodium carbonate, and total dissolved solids determined that groundwater was suitable for irrigation purposes. The discussion in this paper shows that scientific knowledge generated on groundwater quality is not aimed at developing skills and outputs for improved human health and food security but rather for scientific publication and record keeping, leaving communities where such data has been gathered devoid of knowledge about groundwater quality. In this study, it is recommended that research outputs on groundwater quality should be shared with groundwater users through various initiatives.

Experimental study on the exposure level of surgical staff to SARS-CoV-2 in operating rooms with mixing ventilation under negative pressure

The purpose of this study was to reveal the exposure level of surgical staff to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from the patient's nose and wound during operations on COVID-19 patients. The tracer gas N2O is used to simulate SARS-CoV-2 from the patient's nose and wound. In this study, concentration levels of tracer gas were measured in the breathing zones of these surgical staff in the operating room under three pressure difference conditions: −5 pa–15 pa and −25 pa compared to the adjunction room. These influencing factors on exposure level are analyzed in terms of ventilation efficiency and the thermal plume distribution characteristics of the patient. The results show that the assistant surgeon faces 4 to 12 times higher levels of exposure to SARS-CoV-2 than other surgical staff. Increasing the pressure difference between the OR lab and adjunction room can reduce the level of exposure for the main surgeon and assistant surgeon. Turning on the cooling fan of the endoscope imager may result in a higher exposure level for the assistant surgeon. Surgical nurses outside of the surgical microenvironment are exposed to similar contaminant concentration levels in the breathing zone as in the exhaust. However, the ventilation efficiency is not constant near the surgical patient or in the rest of the room and will vary with a change in pressure difference. This may suggest that the air may not be fully mixed in the surgical microenvironment.

An Experimental Study of Indoor Air Pollution in New Office Building

Air pollution is a major environmental risk to health. The new building normally has a facing problem with indoor air pollutant. New construction materials and furniture will contribute higher contaminants compared to old materials. The effect of indoor air pollutants can result in human health problems, discomfort and reduces their productivity. The purpose of this present work is to experimental study the indoor air pollution status regarding carbon dioxide, carbon monoxide, volatile organic compounds, and formaldehyde concentration in an administration office at the new building faculty of mechanical engineering in Johor Bahru, Malaysia. The contaminants concentration values are investigated through field measurements and then compared to the limits stated in the Occupational Safety and Health Act standard. The field measurement of contaminant concentration level was conducted at the intersect plane between the vertical plane at the center of the air conditioning diffuser and the horizontal plane at 1.2 m from the floor. The contaminant concentration readings were taken at 6 locations inside the office. The data were conducted during actual working conditions. The reading of contaminants concentration is taken in 30 minutes. One minute is equal to one number of samples. It was found that only the formaldehyde concentration is exceeding the maximum limit.

Design and Analysis of Mathematical Model for the Concentration of Pollution and River Water Quality

This paper mainly focuses on the recent advances in the mathematical models that provide the ability to predict the contaminant concentration levels of river water. The study represents an attempt for the researchers to study the problem of pollution, and we think that these mathematical analyses would provide better planning for water quality control. The model consists of a pair of coupled reaction Advection-diffusion equations for the pollutant and dissolved oxygen concentrations. Numerical solutions are obtained and some important inferences are drawn through simulation study. The Advection-Diffusion equation is characterized by the reaction term whenever it depends on concentration of the contaminants and in this case the original single Advection-diffusion equation will evolve to be a system of equations. It is no ticked that the higher are diffusion and reaeration coefficients, the faster is the river purity.

Pesticides, nonylphenols and polybrominated diphenyl ethers in marine bivalves from France: A pilot study

The present pilot study aimed to provide an overview of organic contaminant concentration levels in the littoral ecosystems of the Pertuis seas. The study determined the concentrations of twenty-nine pesticides, six nonylphenols and seven polybrominated diphenyl ethers (PBDEs) in sediments, seawater, Pacific oysters and blue mussels. Oysters accumulated a higher number of pesticides than blue mussels. Indeed, alpha BHC (0.60–0.72 ng/g, ww), chlorfenvinphos (1.65–2.12 ng/g, ww), chlorpyrifos (0.79–0.93 ng/g, ww), chlortoluron (2.50–4.31 ng/g, ww), metolachlor (up to 0.38 ng/g, ww) and parathion (0.56–0.69 ng/g, ww) were quantified in oysters whereas only alpha BHC (0.24–0.31 ng/g, ww), was quantified in mussels. The present results also revealed that the POPs detected in water or sediments were not ultimately found accumulated in bivalves. Other molecules such as methylparathion and BDE47 were quantified in sediments. These molecules, BDE99 and one nonylphenol (OP2OE) were quantified in seawater. Finally, the comparison with the available environmental guidelines showed that the values measured were at concentrations not considered to cause adverse effects at the populations' level except for chlortoluron in seawater (15–50 ng/L).

The impact of natural ventilation on airborne biocontaminants: a study on COVID-19 dispersion in an open office

PurposeBiocontaminants represent higher risks to occupants' health in shared spaces. Natural ventilation is an effective strategy against indoor air biocontamination. However, the relationship between natural ventilation and indoor air contamination requires an in-depth investigation of the behavior of airborne infectious diseases, particularly concerning the contaminant's viral and aerodynamic characteristics. This research investigates the effectiveness of natural ventilation in preventing infection risks for coronavirus disease (COVID-19) through indoor air contamination of a free-running, naturally-ventilated room (where no space conditioning is used) that contains a person having COVID-19 through building-related parameters.Design/methodology/approachThis research adopts a case study strategy involving a simulation-based approach. A simulation pipeline is implemented through a number of design scenarios for an open office. The simulation pipeline performs integrated contamination analysis, coupling a parametric 3D design environment, computational fluid dynamics (CFD) and energy simulations. The results of the implemented pipeline for COVID-19 are evaluated for building and environment-related parameters. Study metrics are identified as indoor air contamination levels, discharge period and the time of infection.FindingsAccording to the simulation results, higher indoor air temperatures help to reduce the infection risk. Free-running spring and fall seasons can pose higher infection risk as compared to summer. Higher opening-to-wall ratios have higher potential to reduce infection risk. Adjacent window configuration has an advantage over opposite window configuration. As a design strategy, increasing opening-to-wall ratio has a higher impact on reducing the infection risk as compared to changing the opening configuration from opposite to adjacent. However, each building setup is a unique case that requires a systematic investigation to reliably understand the complex airflow and contaminant dispersion behavior. Metrics, strategies and actions to minimize indoor contamination risks should be addressed in future building standards. The simulation pipeline developed in this study has the potential to support decision-making during the adaptation of existing buildings to pandemic conditions and the design of new buildings.Originality/valueThe addressed need of investigation is especially crucial for the COVID-19 that is contagious and hazardous in shared indoors due to its aerodynamic behavior, faster transmission rates and high viral replicability. This research contributes to the current literature by presenting the simulation-based results for COVID-19 as investigated through building-related and environment-related parameters against contaminant concentration levels, the discharge period and the time of infection. Accordingly, this research presents results to provide a basis for a broader understanding of the correlation between the built environment and the aerodynamic behavior of COVID-19.

RETRACTED ARTICLE: Development of air quality monitoring (AQM) models using different machine learning approaches

Air Quality assessment and forecasting are the essentials today and they attracted many researchers. Environmental organizations regularly monitor and predict the air contaminants to make the public awareness, provide a better environment, and suitable for human health. Physical factors like climate changes, Industrialization, Fires and Urbanization are some of the factors which directly affect and reduce the air quality. All these data are time-series and real-time data. The primary pollutant is PMx that affect the respiratory systems and cardiac activity of humans. The secondary pollutants are SO2, CO, NOx, and O3. Each has allowable range of concentration levels. In this work, meteorological elements are collected in different locations in last 5 years, with time window of 24 h and mapped to the concentration level of pollutants. The Machine Learning(ML) Methods such as Non-Linear Artificial Neural Network(ANN), Statistical Multilevel Regression, Neuro- Fuzzy and Deep Learning Long-Short-Term Memory (DL-LSTM) are used; to find the current concentration level of pollutants and will be useful for Real Time Correction (RTC) to give a feedback that can be used to reduce the contaminants in air for further days. The results are compared with the parameters such as R2, RMSE and MAPE. Using these methods, the concentration level of contaminants is predicted with the deviation of R2 in the range of 0.71–0.89. The results proved that DL-LSTM suits well when comparing to the ANN, Neuro-fuzzy and regression algorithms.

On the conceptual complexity of non-point source management: impact of spatial variability

Abstract. Non-point source (NPS) pollution has degraded groundwater quality of unconsolidated sedimentary basins over many decades. Properly conceptualizing NPS pollution from the well scale to the regional scale leads to complex and expensive numerical models: key controlling factors of NPS pollution – recharge rate, leakage of pollutants, and soil and aquifer hydraulic properties – are spatially and, for recharge and pollutant leakage, temporally variable. This leads to high uncertainty in predicting well pollution. On the other hand, concentration levels of some key NPS contaminants (salinity, nitrate) vary within a limited range (&lt; 2 orders of magnitude), and significant mixing occurs across the aquifer profile along the most critical compliance surface: drinking water wells with their extended vertical screen length. Given these two unique NPS contamination conditions, we here investigate the degree to which NPS travel time to wells and the NPS source area associated with an individual well can be appropriately captured, for practical applications, when spatiotemporally variable recharge, contaminant leakage rates, or hydraulic conductivity are represented through a sub-regionally homogenized parametrization. We employ a Monte Carlo-based stochastic framework to assess the impact of model homogenization on key management metrics for NPS contamination. Results indicate that travel time distributions are relatively insensitive to the spatial variability of recharge and contaminant loading, while capture zone and contaminant time series exhibit some sensitivity to source variability. In contrast, homogenization of aquifer heterogeneity significantly affects the uncertainty assessment of travel times and capture zone delineation. Surprisingly, the statistics of relevant NPS well concentrations (fast and intermediate travel times) are fairly well reproduced by a series of equivalent homogeneous aquifers, highlighting the dominant role of NPS solute mixing along well screens.

Differential toxic effects of food contaminant mixtures in HepaRG cells after single or repeated treatments

Through diet, people are chronically exposed to low doses of a large number of contaminants that could exhibit adverse health effects. Toxicological evaluation of food contaminants increases in complexity when the exposure involves chemical mixtures. The aim of this study is to investigate the genotoxic potential, through measuring ©H2AX induction, of six common mixtures of food contaminants to which French adult consumers are chronically exposed. Mixtures were identified by combining information from consumption surveys and contaminant concentration levels in foods. Both single and repeated exposures were evaluated in human liver-derived HepaRG cells. Our results indicated that after a single 24-h exposure, only one mixture induced genotoxicity, and that response occurred at the highest concentration tested. In contrast, we observed after repeated exposures over 3 or 7 days, induction of ©H2AX for all mixtures except one, and a time- and concentration-dependent manner toxicity for four mixtures. Interestingly, we also observed a non-monotonic cytotoxicity concentration-response for one mixture, which might reflect cellular adaptation to the exposure. In conclusion, our study demonstrated that longer-term treatments for in vitro toxicological evaluation, instead of the classical 24 h treatment, may be more relevant regarding human toxicology assessment.

Aggregated GP-based Optimization for Contaminant Source Localization

Recently a new simulation-based optimization benchmark of groundwater contaminant source localization problems has been introduced to the hydrogeological science community. Given information on contaminant concentration levels at each monitoring well and each time step, its objective is to identify the location of contaminant source. In this work, we analyze and look at the problem from different angles to gain more insights on this class of groundwater problems. To tackle the problem, a novel simulation-based optimization algorithm relying on an aggregated Gaussian process model, and the expected improvement criterion is introduced. Results from this study show that the proposed algorithm, though relying on an approximated Gaussian process model, demonstrates superior efficiency and reliability than a traditional expected improvement-based algorithm. The location of the monitoring wells was confirmed to play a crucial role in assisting the optimization algorithm to accurately localize the contaminant source. Additional monitoring wells, while adding more knowledge of the space-time mapping of concentration levels, could nevertheless slow down convergence of the algorithm due to the increase in problem complexity.

Groundwater contamination in mega cities with finite sources

Groundwater contamination due to multiple sources occurring in mega cities was modelled. One constant source contamination was considered at the source boundary, whereas other sources may join in between at various locations at different times. Initially, the aquifer was contamination-free in mega cities and was subsequently contaminated by means of different sources in due course of time. One-dimensional ADE (Advection Dispersion Equation) for modelling groundwater contamination was used and solved analytically in the semi-infinite aquifer domain for a finite number of point sources. A numerical solution was also obtained for two sources to compare analytical solutions. Results were examined for different velocity profiles to show the maximum contaminant concentration level with distance. This may be helpful to model the maximum possible number of point sources of contamination (i.e., it represents approximately what happens in the field situation). Some remedial measures may be taken to overcome these kinds of contamination problems in mega cities by treating the sources so that recharge of the aquifer is not affected.

Levels of Minor and Trace Elements of Some Commercial Fruit Juices and Syrup Produced in Artisanal and Semi-Industrial Units in Benin Republic

Fruit juices have been gaining interest in recent years for their contributions of minerals and other essential vitamins. But, with the development of intensive agriculture massively using pesticides and mineral fertilizers, the risk of contamination of these juices is high along the production chain. In this study, we evaluated the concentrations of arsenic&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; (As), cadmium (Cd), berrylium (Be), aluminium (Al), strontium (Sr), tin&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; (Sn), barium (Ba), mercury (Hg), thallium&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; (Tl), lead&amp;nbsp;&amp;nbsp; (Pb), thorium (Th), uranium (U) for 92 commercial samples of pineapple juice, cocktail of pineapple and watermelon and pineapple syrup of Benin and France using Inductively Coupled Plasma-Source Mass Spectrometry (ICP-MS). The concentrations vary in the following ranges: As &amp;lt;QL at 39.3 ppb, Cd &amp;lt;QL at 0.7 ppb, Be &amp;lt;QL at 0.59 ppb, Al 26.4 ppb at 30620 ppb, Sr 130 ppb at 4049 ppb, Sn&amp;lt;QL at 43 ppb, Ba 42 ppb at 1582 ppb, Hg &amp;lt;QL at 31.7 ppb, Tl&amp;lt;QL at 21.3 ppb, Pb&amp;lt;QL at 608 ppb, Th&amp;lt;QL at 24.7 ppb ppb and U &amp;lt;QL at 1.04 ppb. Se, Ag and Pt have concentrations below the quantification limit (&amp;lt;QL). The levels of Ba, Hg and Pb exceeded the norms for some samples. The presence of aluminum, arsenic and cadmium in the tested samples of fruit juices can be toxic since they have no nutritional value, and hence may be treated as potential contaminants in these beverages. The classification of concentration levels of metallic contaminants reveals two main groups, the minor and the trace elements. These results make it possible to classify the contaminants in the decreasing order of the concentrations in the following way: Al&amp;gt; Sr&amp;gt; Ba&amp;gt; Pb&amp;gt; Sn&amp;gt; Tl&amp;gt; As&amp;gt; Th&amp;gt; Hg&amp;gt; Cd&amp;gt; Be&amp;gt; U. The average concentrations&amp;rsquo; levels of trace elements are generally in accordance with the levels obtained for French pineapple juices chosen as reference, national and international standards for the quality of beverages.

Emission spread from mass and energy exchange in the atmospheric surface layer: Two-dimensional simulation

ABSTRACTThis article provides an original method for simulating the spread of hazardous emissions in the atmospheric surface layer in the event of emergencies The modeling process implies the development of a mathematical tool based on the partial differential equation (PDE) of turbulent diffusion. It is also based on a steady-state equation for determining the contaminant dispersion during an emergency with regard to the elapsed dispersion time, volumetric nature of the contamination source, wind speed. The model allows studying the changes in air composition that have occurred under various meteorological (wind speed and direction, temperature, fogs, precipitation, dust winds) and anthropogenous factors. An attempt was made to calculate the probable contamination area around the arbitrary system of sources with high contaminant concentration under unfavorable weather conditions. The original method for calculating the movement and dispersion of emissions allows forecasting the contaminant concentration level in the two-meter layer above the ground and the vertical concentration distribution with regard to the landscape, identified according to the meteorological data. Our model can be easily scaled on any territory; the entire line of complex landscape features was taken into account by introducing a model of weather statistics for the research region.