Removal of Sb(V) from complex wastewater of Sb(V) and aniline aerofloat using Fe3O4-CeO2 absorbent enhanced by H2O2: Efficiency and mechanism.

Effective elimination of heavy metals from complex wastewater is of great significance for industrial wastewater treatment. Herein, bimetallic adsorbent Fe3O4-CeO2 was prepared, and H2O2 was added to enhance Sb(V) adsorption by Fe3O4-CeO2 in complex wastewater of Sb(V) and aniline aerofloat (AAF) for the first time. Fe3O4-CeO2 showed good adsorption performance and could be rapidly separated by external magnetic field. After five adsorption/desorption cycles, Fe3O4-CeO2 still maintained good stability. The maximum adsorption capacities of Fe3O4-CeO2 in single Sb(V), AAF + Sb(V), and H2O2+AAF + Sb(V) systems were 77.33, 70.14, and 80.59 mg/g, respectively. Coexisting AAF inhibited Sb(V) adsorption. Conversely, additional H2O2 promoted Sb(V) removal in AAF + Sb(V) binary system, and made the adsorption capacity of Fe3O4-CeO2 increase by 14.90%. H2O2 could not only accelerate the reaction rate, but also reduce the optimal amount of adsorbent from 2.0 g/L to 1.2 g/L. Meanwhile, coexisting anions had little effect on Sb(V) removal by Fe3O4-CeO2+H2O2 process. The adsorption behaviors of Sb(V) in three systems were better depicted by pseudo-second-order kinetics, implying that the chemisorption was dominant. The complexation of AAF with Sb(V) hindered the adsorption of Sb(V) by Fe3O4-CeO2. The complex Sb(V) was oxidized and decomposed into free state by hydroxyl radicals produced in Fe3O4-CeO2+H2O2 process. Then the free Sb(V) was adsorbed by Fe3O4-CeO2 mostly through outer-sphere complexation. This work provides a new tactic for the treatment of heavy metal-organics complex wastewater.

Mechanistic analysis of the sub chronic toxicity of La and Gd in Daphnia magna based on TKTD modelling and synchrotron X-ray fluorescence imaging.

The release of lanthanides (Ln) into the environment has increased in recent decades due to their expanding applications in society. Studying their toxicity in aquatic ecosystems is urgent and challenging, with contradictory evidence presented in the literature. This study compared the biodistribution of La and Gd in Daphnia magna exposed to sub-chronic conditions and developed the first Toxicokinetic-Toxicodynamic (TKTD) model for these lanthanides with this model crustacean. D. magna were initially exposed for 7 days to concentrations close to the LC50 of La (2.10 mg L-1) and Gd (1.70 mg L-1). After exposure, half of the live daphnids were introduced in a clean media to allow depuration over 24 h, while the other organisms were directly prepared for synchrotron imaging measurements. Synchrotron X-ray fluorescence analysis revealed that metal distribution in the organisms was similar for both La and Gd, predominantly localized in the intestinal tract, even after the depuration process. These results indicate that ingested metal can adversely affect organisms under sub-chronic exposure conditions, highlighting the importance of using nominal concentrations as a more suitable indicator of metal bioavailability for risk assessment. The General Unified Threshold Model of Survival (GUTS) TKTD framework, in its reduced form (GUTS-RED), was developed for La and Gd using dissolved and nominal concentrations. D. magna were exposed for 7 days to concentrations from 0.5 to 5 mg L-1 of La or Gd and mortality monitored daily. The mechanistic model revealed a faster toxicokinetics for La than Gd and a higher toxicity for Gd than La in the organism. This study confirmed, despite similar chemical properties, the variation in both toxicity and toxicokinetics between these two metals.

Modelling selenium behavior in aquatic systems: a review of status, challenges, and opportunities.

Selenium (Se) is an essential element for aquatic organisms as well as humans. It can be toxic to organisms depending on its concentration and chemical speciation; thus, considerable efforts have been made to unravel the biogeochemical cycling of Se in aquatic systems. Mathematical models provide an important tool to better understand the fate of Se in different environment compartments. However, a comprehensive review of modeling Se in aquatic systems with current challenges and opportunities is missing. To fill this gap, we firstly summarize the processes governing Se cycling in aquatic systems, including particle adsorption and desorption, diffusion, biological uptake, redox reactions, and volatilization. Then, we critically review the available models, identifying the compartments modelled, environmental factors considered, and the Se species and geochemical processes used in each model, providing an assessment of their advantages and limitations. Data availability for modeling studies is investigated, highlighting how to better quantify the redox reactions, estimate of Se loadings, and mass balance. For the modeling of Se cycling in aquatic systems, the ability of the models to link sources to biota concentrations under a range of hydrodynamic conditions and with mechanistic representations of transport, transformation, and uptake processes is required. The majority of the current models can conduct this task; however, to better present the uptake processes of Se in the food web, two-way coupling of the Se cycling model with a food web model is recommended.

Determination of the distribution of rare earth elements La and Gd in Daphnia magna via micro and nano-SXRF imaging.

While our awareness of the toxicity of rare earth elements to aquatic organisms increases, our understanding of their direct interaction and accumulation remains limited. This study describes the acute toxicity of lanthanum (La) and gadolinium (Gd) in Daphnia magna neonates and discusses potential modes of action on the basis of the respective patterns of biodistribution. Ecotoxicological bioassays for acute toxicity were conducted and dissolved metal concentrations at the end of the tests were determined. The results showed a significant difference in nominal EC50 (immobility) between La (>30 mg L-1) and Gd (13.93 (10.92 to 17.38) mg L-1). Daphnids that were then exposed to a concentration close to the determined EC50 of Gd (15 mg L-1, nominal concentration) for 48 h and 72 h were studied by synchrotron micro and nano-X-ray fluorescence to evaluate the biodistribution of potentially accumulated metals. X-ray fluorescence analyses showed that La was mainly found in the intestinal track and appeared to accumulate in the hindgut. This accumulation might be explained by the ingestion of solid La precipitates formed in the media. In contrast, Gd could only be detected in a small amount, if at all, in the intestinal tract, but was present at a much higher concentration in the tissues and became more pronounced with longer exposure time. The solubility of Gd is higher in the media used, leading to higher dissolved concentrations and uptake into tissue in ionic form via common metal transporting proteins. By studying La and Gd biodistribution in D. magna after an acute exposure, the present study has demonstrated that different uptake pathways of solid and dissolved metal species may lead to different accumulation patterns and toxicity.

Hybrid leaching of tantalum and other valuable metals from tantalum capacitor waste.

We propose a novel integrated model for the recovery of tantalum from tantalum-rich waste using a combination of hydrometallurgical and bio-metallurgical processes. To this end, leaching experiments with heterotrophs (Pseudomonas putida, Bacillus subtilis and Penicillium simplicissimum) were carried out. The heterotrophic fungal strain leached manganese with an efficiency of 98%; however, no tantalum was detected in the leachate. An unidentified species did mobilise 16% tantalum in 28 days in an experiment with non-sterile tantalum capacitor scrap. Attempts to cultivate isolate and identify these species failed. The results of a range of leaching trials resulted in an effective strategy for Ta recovery. A bulk sample of homogenised Ta capacitor scrap was first subjected to microbial leaching using Penicillium simplicissimum, which solubilised manganese and base metals. The residue was subjected to the second leach using 4 M HNO3. This effectively solubilised silver and other impurities. The residue collected after the second leach was pure tantalum in concentrated form. The hybrid model produced derives from observations from previous independent studies and shows that we can effectively recover tantalum along with silver and manganese in an efficient and environmentally friendly manner from tantalum capacitor scrap.

Manganese oxides mediated dissolve organic matter compositional changes in lake sediment and cadmium binding characteristics.

In sediment environments, manganese (Mn) minerals have high dissolved organic matter (DOM) affinities, and could regulate the changes of DOM constituents and reactivity by fractionation. However, the effects of DOM fractionation by Mn minerals on the contaminant behaviors remain unclear. Herein, the transformations of mineral phases, DOM properties, and Cd(II) binding characteristics to sediment DOM before and after adsorption by four Mn oxides (δ-MnO2, ß-MnO2, γ-MnOOH, and Mn3O4) were investigated using multi-spectroscopic tools. Results showed a subtle structural variation of Mn oxides in response to DOM reduction, and no phase transformations were observed. Two-dimensional correlation spectroscopy based on synchronous fluorescence spectra and Fourier transform infrared spectroscopy indicated that tryptophan-like substances and the amide (II) N-H groups could preferentially interact with Cd(II) for the original DOM. Nevertheless, preferential bonding of Cd(II) to tyrosine-like substances and phenolic OH groups was exhibited after fractionations by Mn oxides. Furthermore, the binding stability and capacity of each DOM fraction to Cd(II) were decreased after fractionation based on the modified Stern-Volmer equation. These differences may be attributed to DOM molecules with high aromaticity, hydrophobicity, molecular weight, and amounts of O/N-containing group were preferentially removed by Mn oxides. Overall, the environmental hazard of Cd will be more severe after DOM fractionation on Mn minerals. This study facilitates a better understanding of the Cd geochemical cycle in lake sediments under the DOM-mineral interactions, and recommends being careful with outbreaks of aquatic Cd pollution when sediments are rich in dissolved protein-like components and Mn minerals.

Exploring the Joint Association of Road Traffic Noise and Air Quality with Hypertension Using QGIS.

There is growing evidence linking exposure to air pollution and traffic noise with hypertension. The aim of this study was to examine the associations of registered hypertension cases and hypertension rate with exposure to air pollution and road noise. In this cross-sectional study, we linked the information from the NHS Scotland database of 776,579 hypertension patients' registrations and rates per 13.80 people at the Scottish NHS Board, HSCP, Cluster, and GP practice levels. Based on the geospatial attributes, the data on residential areas were added by modelling annual average air pollutant concentrations, including particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), and road-traffic noise at different frequency components (Lden). The relationships between exposure to road noise, air pollution, and hypertension were examined using multiple regression and multivariate analysis. Traffic noise and air pollution at various frequency components positively and negatively predicted registered hypertension cases and hypertension rate. Based on the canonical loading technique, the variance explained by the canonical independent variable at a canonical correlation of 0.342 is 89%. There is a significant correlation between joint air pollution and noise at different frequency components and combined registered hypertension cases and hypertension rate. Exploring the combined effects of the two environmental exposures and the joint modelling of noise and air pollutants with hypertension in geospatial views provides an opportunity to integrate environmental and health data to support spatial assessment strategies in public and environmental health.

The waste ban in China: what happened next? Assessing the impact of new policies on the waste management sector in China.

The 2017 ban on the waste import and new policies for the waste management sector in mainland China had wide-spread impact. After decades of poor environmental and public health impacts from the sector, a study is needed which focuses on policies updates and waste management. This provides a direction for the survival of local waste management industries and consider similarities with the ban promulgated in China on the restriction of waste import from other countries. We review the waste management situation in China before national legislation prevented the import of waste, highlight the status of landfill mining in China, and review the dynamics of domestic policies before and after the promulgation of the ban in China. The impact of the COVID19 pandemic on the waste management system is starting to emerge, providing both challenges and opportunities for the sector in China. We see the impact of the ban on the range of imported waste and domestically generated materials. The ban results in price increases for domestic recycling that forces companies to introduce more formal recycling processes and to drive the consumption behaviours to more reasonable and environmentally friendly options. The driver in China is to reduce pollution in the environment and improve health, but a negative impact has been from increased landfill mining which has impeded the original aim of the waste ban and requires further technological development. The dynamic of domestic policies in China shows higher level of activity of updates and revisions or introduction of new policies from 2015 onwards and the concept of 'zero waste cities' brings new hope for improvement of the Chinese waste management system. The pandemic also suggests an important step to establish sustainable management systems despite evidence of increased "fly-tipping". The rebound of the waste ban may have stimulated in the short term negative impacts on local environments both in China and internationally.

Separation of dye from aqueous solution by a new gravity compression and aeration system.

Filtration is one of the important technologies for separating suspended particles. Under the condition of gravity compression, the filtration density can be increased and the separation effect of suspended particles can be improved. Considering the complex composition and the difficulty in degrading dye in industrial wastewater, a gravity compression aeration system with a modified polyester fibre ball (denoted as MPFB) was evaluated for the separation of dye from water. Congo red azo dye solution (0-40 mg/L) was selected as the model treatment compound. The MPFB was prepared by adjusting the concentrations of alkali (Quality score 0-25%), ß-cyclodextrin (0∼80 g/L), reaction temperature (40-90°C), and silane coupler concentration (Concentration fractions 0-0.8%). We used Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterise the MPFB. The separation was affected significantly by adsorption conditions such as MPFB dose and pH. The lower the MPFB dose, the higher the expected adsorption capacity. For the treatment of a dye solution at 500 mg/L, 100% removal was achieved with 48 g/L MPFB, at pH 8 during adsorption under non-circulation aeration. For 24 h of reaction, the system could reach the maximum adsorption capacity of 11.2 mg/g, which followed the pseudo-first order kinetics model and the intraparticle diffusion model. We discovered that circulation aeration provided the best adsorption and electrostatic and hydrogen bonding were the dominant components of adsorption. Overall, the system is a promising technology and has the potential to treat large volumes of dye wastewater.

Exploring the Combined Association between Road Traffic Noise and Air Quality Using QGIS.

There is mounting evidence that exposure to air pollution and noise from transportation are linked to the risk of hypertension. Most studies have only looked at relationships between single exposures. To examine links between combined exposure to road traffic, air pollution, and road noise. A Casella CEL-63x instrument was used to monitor traffic noise on a number of locations in residential streets in Glasgow, UK during peak traffic hours. The spatial numerical modelling capability of Quantum GIS (abbreviated QGIS) was used to analyse the combined association of noise and air pollution. Based on geospatial mapping, data on residential environmental exposure was added using annual average air pollutant concentrations from local air quality monitoring network, including particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), and road-traffic noise measurements at different component frequencies (Lden). The combined relationships between air pollution and traffic noise at different component frequencies were examined. Based on Moran I autocorrelation, geographically close values of a variable on a map typically have comparable values when there is a positive spatial autocorrelation. This means clustering on the map was influenced significantly by NO2, PM10 and PM2.5, and Lden at the majority of monitoring locations. Studies that only consider one of these two related exposures may exaggerate the impact of the individual exposure while underestimating the combined impact of the two environmental exposures.

The Effect of Substrate on Water Quality in Ornamental Fish Tanks.

Almost all home aquaria contain substrate, either as intentional enrichment or for aesthetic purposes. For fishes, benefits of structural enrichment have been well considered, particularly in research and aquaculture settings. However, our understanding of the impacts of tank substrate as enrichment is limited. While substrate can induce foraging in some species, a major drawback is the potential of substrate to harbour elevated levels of waste and pathogenic bacteria. Here, we considered whether substrate as a form of environmental enrichment significantly altered water quality and bacterial presence in home aquaria. Water quality (temperature, oxygen, pH, TAN, unionised ammonia, nitrate, Ca2+, Na+, Mg2+ and K+) and bacterial presence (Pseudomonas spp.) were measured over two seven-week periods in stand-alone, tropical, freshwater tanks that simulated home aquaria. The following four enrichment conditions were considered: bare tanks, plastic plants, gravel substrate or sand substrate. The addition of both gravel and sand resulted in increased pH, concentrations of total ammonia nitrogen and nitrate. Substrate was also associated with a greater Pseudomonas presence. Decreased pH alongside an increased concentration of ions were also observed depending on the time of year. In conclusion, enrichment type affected the water quality of home aquaria, with further research needed on the role of the tank biome in fish welfare.

Chemical and Microbial Leaching of Valuable Metals from PCBs and Tantalum Capacitors of Spent Mobile Phones.

We compared chemical and microbial leaching for multi-metal extraction from printed circuit boards (PCBs) and tantalum capacitor scrap. A mixed consortium of acidophiles and heterotrophic fungal strains were used in the experiments and compared to chemical leaching using specific acids (sulfuric, citric and oxalic acids). Under optimum conditions, 100% extraction efficiency of Cu, and nearly 85% of Zn, Fe, Al and Ni were achieved from PCB and tantalum capacitor scrap samples using sulfuric acid. The mixed consortium of acidophiles successfully mobilized, Ni and Cu (99% and 96%, respectively) while Fe, Zn, Al and Mn reached an extraction yield of 89, 77, 70 and 43%, respectively, from the PCB samples. For the tantalum capacitor samples, acidophiles mobilized 92% Cu, 88% Ni, 78% Fe, 77% Al, 70% Zn and 57% Mn. Metal mobilization from PCBs and tantalum capacitor scrap by A. niger filtrate showed efficient solubilization of Cu, Fe, Al, Mn, Ni, Pb and Zn at an efficiency of 52, 29, 75, 5, 61, 21 and 35% from PCB samples and 61, 25, 69, 23, 68, 15 and 45% from tantalum capacitor samples, respectively. Microbial leaching proved viable as a method to extract base metals but was less specific for tantalum and precious metals in electronic waste. The implications of these results for further processing of waste electronic and electrical equipment (WEEE) are considered in potential hybrid treatment strategies.

Sorption vs adsorption: The words they are a-changin', not the phenomena.

In this discussion, we highlight that the terms sorption and adsorption are often confused and misused in many articles. Even if one thought their formal definition is well known, this does not appear to be the case. We recommend encouragement to adopt the word adsorption only when fully supported by appropriate data and using the sorption terminology when it is more speculative, typically in complex solid/fluid natural systems.

Antimicrobial Resistance as a Global Health Threat: The Need to Learn Lessons from the COVID-19 Pandemic.

The global COVID-19 pandemic has exacerbated existing health, social, and economic challenges and threatened progress towards achieving the UN sustainable development goals. We discuss lessons learned from the COVID-19 pandemic for global policymaking for health security governance, with a particular focus on antimicrobial resistance. We identify One Health as the primary foundation of public health risk management owing to the collaborative, multidisciplinary, and multisectoral efforts that underpin the One Health approach and that enhance understanding of the complex interactions at the human-animal-environment interface. We discuss the narrow human-centric focus of the One Health approach, highlight the underrepresentation of the environmental sector in One Health networks, and encourage greater representation from the environmental sector. Furthermore, we highlight the importance of the social sciences for health security research and the need for effective communication and trust. Finally, we underscore the importance of strengthened and collaborative health, social care, and disaster management systems. The application of these lessons will facilitate holistic, multisectoral, collaborative, and ethical actions on antimicrobial resistance.

New Models to Reduce the Health Risks of Informal WEEE Recyclers in MTN Phone Village, Rumukurushi, Port Harcourt, Nigeria.

Waste electrical and electronic equipment (WEEE) management in Port Harcourt, an oil-producing city in Nigeria, has become an environmental challenge for the location. WEEE recycling is predominantly managed by informal recyclers, who lack the skills to perform risk-free recycling, hence raising health risks to individuals in associated communities and degrading the environment. Formal recycling, which embraces the best practices for effective WEEE management, is faced with several limitations, such as a lack of detailed guidelines on waste recycling, reuse, and final disposal techniques, with no opportunities for landfilling. A qualitative approach was adopted for this study. Data were gathered via questionnaires and analysed graphically. A background literature review of the assessment of informal recycling methods and associated challenges was performed. Hence, a new concept for the local management of WEEE processing was introduced. This concept limits the role of informal recyclers to WEEE collection. In this case, informal recyclers are paid for WEEE collection; they no longer engage in further WEEE processing. The results show that 48% and 40% agree to partner and collaborate with government agencies, respectively. Conversely, 52% and 40% agree and strongly agree, respectively, to limit their activities to WEEE collection only if the government is willing to pay for the services.

Recycling Plastics from WEEE: A Review of the Environmental and Human Health Challenges Associated with Brominated Flame Retardants.

Waste electrical and electronic equipment (WEEE) presents the dual characteristic of containing both hazardous substances and valuable recoverable materials. Mainly found in WEEE plastics, brominated flame retardants (BFRs) are a component of particular interest. Several actions have been taken worldwide to regulate their use and disposal, however, in countries where no regulation is in place, the recovery of highly valuable materials has promoted the development of informal treatment facilities, with serious consequences for the environment and the health of the workers and communities involved. Hence, in this review we examine a wide spectrum of aspects related to WEEE plastic management. A search of legislation and the literature was made to determine the current legal framework by region/country. Additionally, we focused on identifying the most relevant methods of existing industrial processes for determining BFRs and their challenges. BFR occurrence and substitution by novel BFRs (NBFRs) was reviewed. An emphasis was given to review the health and environmental impacts associated with BFR/NBFR presence in waste, consumer products, and WEEE recycling facilities. Knowledge and research gaps of this topic were highlighted. Finally, the discussion on current trends and proposals to attend to this relevant issue were outlined.

Source identification and groundwater health risk assessment of PTEs in the stormwater runoff in an abandoned mining area.

Xikuangshan antimony mine in Lengshuijiang, China, has been developed for many years, and stormwater runoff contains high levels of potentially toxic elements (PTEs). The aims were to find the sources of PTEs by statistical analysis and local spatial distribution of industrial activity and simulate transport process of PTEs in the soil to evaluate pollution extent and health risk. The PTEs in this study were antimony, cadmium, zinc, nickel, lead, and copper. The result showed antimony and a minor portion of zinc were derived from the antimony processing activities, copper derived from agricultural activities, and most of the zinc came from the zinc industry. Nickel, lead, and cadmium came from a mixed source of atmospheric transportation, vehicle transport, and other local industrial activities. Besides, antimony was the most hazardous element in this mining area. In the fourth year, the groundwater in the whole area was uncontaminated by antimony, and there was no non-carcinogenic health risk. Except for the southern area of Lianxi River and the area enclosed by South mine, Zhumushan village, and Tailing Dam, there was a non-carcinogenic risk at year 5.4. These sources of PTEs found in the stormwater runoff are useful for locals to control of PTEs pollution. And the health risk assessment method helps evaluate the risk of PTEs caused by stormwater runoff.

Effects of mining activities on the distribution, controlling factors, and sources of metals in soils from the Xikuangshan South Mine, Hunan Province.

In this study, we analyzed 53 topsoil samples from the Xikuangshan South Mine in Hunan Province to investigate the distribution characteristics of pH and the concentrations of selected metals to determine the controlling factors and identify their sources. Kriging interpolation, correlation analysis, principal component analysis, the index of the geoaccumulation index, and Hakanson's potential ecological risk were applied. The results show that the mean values of Pb, As, Cd, and Sb in the study area were larger than the background value of mountain soil in Hunan Province, and only the average Cr concentration was slightly lower than the background value. The spatial distributions of pH and five metals in the soil were very different, indicating that pH had no significant effect on the distribution of the metals. The wind, rivers, and land-use patterns in different regions of the study area may be the main reasons for their distribution patterns. The correlation component and principal component analysis revealed that Pb showed positive correlations with Cr and Cd, respectively, and Sb-As and Cr-Cd showed strong paired correlations. The cumulative proportion of the first two components accounted for 70.516% of the total variance, which suggests that mining activities are a major source of As and Sb, whereas Pb, Cr, and Cd were derived from natural and anthropogenic sources. The geoaccumulation index revealed that the major pollutants in the soils were mainly Cd, followed by Sb and As. The soils in the study area were moderately contaminated with Pb and lightly polluted by Cr. The ecological hazards of each metal in descending order were Cd > Sb > As > Pb > Cr. The index of the comprehensive potential ecological risk for metals indicated that the Xikuangshan South Mine is at or above a moderate ecological risk level, with an extremely strong potential for ecological risks posed by Cd and Sb. Integr Environ Assess Manag 2022;18:748-756. © 2021 SETAC.

A Critical Review of Resistance and Oxidation Mechanisms of Sb-Oxidizing Bacteria for the Bioremediation of Sb(III) Pollution.

Antimony (Sb) is a priority pollutant in many countries and regions due to its chronic toxicity and potential carcinogenicity. Elevated concentrations of Sb in the environmental originating from mining and other anthropogenic sources are of particular global concern, so the prevention and control of the source of pollution and environment remediation are urgent. It is widely accepted that indigenous microbes play an important role in Sb speciation, mobility, bioavailability, and fate in the natural environment. Especially, antimony-oxidizing bacteria can promote the release of antimony from ore deposits to the wider environment. However, it can also oxidize the more toxic antimonite [Sb(III)] to the less-toxic antimonate [Sb(V)], which is considered as a potentially environmentally friendly and efficient remediation technology for Sb pollution. Therefore, understanding its biological oxidation mechanism has great practical significance to protect environment and human health. This paper reviews studies of the isolation, identification, diversity, Sb(III) resistance mechanisms, Sb(III) oxidation characteristics and mechanism and potential application of Sb-oxidizing bacteria. The aim is to provide a theoretical basis and reference for the diversity and metabolic mechanism of Sb-oxidizing bacteria, the prevention and control of Sb pollution sources, and the application of environment treatment for Sb pollution.

Development and Validation of a Box and Flux Model to Describe Major, Trace and Potentially Toxic Elements (PTEs) in Scottish Soils.

The box and flux model is a mathematical tool used to describe and forecast the major and trace elements perturbations of the Earth biogeochemical cycles. This mathematical tool describes the biogeochemical cycles, using kinetics of first, second and even third order. The theory and history of the box and flux modeling are shortly revised and discussed within the framework of Jim Lovelok's Gaia theory. The objectives of the investigation were to evaluate the natural versus anthropic load of Potentially Toxic Elements (PTEs) of the Scottish soils, investigate the soil components adsorbing and retaining the PTEs in non-mobile species, evaluate the aging factor of the anthropic PTEs and develop a model which describes the leaching of PTEs in layered soils. In the Scottish land, the soil-to-rock enrichment factorinversely correlates with the boiling point of the PTEs. The same is observed in NW Italy and USA soils, suggesting the common source of the PTEs. The residence time in soils of the measured PTEs linearly correlates with the Soil Organic Matter (SOM). The element property which mostly explains the adsorption capacity for PTEs' is the ionic potential (IP). The downward migration rates of the PTEs inversely correlate with SOM, and in Scottish soil, they range from 0.5 to 2.0 cm·year-1. Organic Bentoniteis the most important soil phase adsorbing cation bivalent PTEs. The self-remediation time of the polluted soil examined ranged from 50 to 100 years. The aging factor, the adsorption of PTEs' into non-mobile species, and occlusion into the soil mineral lattice was not effective. The box and flux model developed, tested and validatedhere does not describe the leaching of PTEs following the typical Gaussian shape distribution of the physical diffusion models. Indeed, the mathematical model proposed is sensitive to the inhomogeneity of the layered soils.