Retention Of Pollutants Research Articles

The Roughness Effect on the Preparation of Durable Superhydrophobic Silver-Coated Copper Foam for Efficient Oil/Water Separation

In recent decades, there has been a significant interest in superhydrophobic coatings owing to their exceptional properties. In this research work, a superhydrophobic coating was developed on copper foams with a different roughness via immersion in AgNO3 and stearic acid solutions. The resulting foams exhibited water contact angles of 180°. Notably, surface roughness of the substrate influenced the development of silver dendrites and stearic acid morphologies, leading to different structures on rough and smooth copper foams. Separation efficiency was maintained above 94% for various pollutants, suggesting good stability and durability, irrespective of the substrate’s roughness. Conversely, absorption capacity was influenced by surface roughness of the substrate, with smooth copper foams demonstrating higher absorption values, primarily due to its uniform porosity and microstructure, which allowed for efficient retention of pollutants. Both copper foams exhibited excellent thermal and chemical stability and maintained their hydrophobic properties even after a 40 h exposure to harsh conditions. Mechanical durability of modified copper foams was tested by dragging and in ultrasounds, exhibiting promising results. The samples with the smooth substrate demonstrated improved coating stability.

Fine-scale geographic risk assessment of oxybenzone sunscreen pollution within Hanauma Bay using hydrodynamic characterization and modeling

Hanauma Bay's coral reef system is threatened by sunscreen pollution. Understanding the hydrodynamic nature of the bay is crucial for understanding the transport and fate of pollutants within the bay. This study conducted a comprehensive hydrodynamic analysis, revealing significant aspects of current patterns and their influence on sunscreen pollutant behavior. The analysis demonstrated the formation of flows that drive currents parallel to the shoreline, resulting in increased pollutant retention time over sensitive reef areas. Direct flushing currents were identified as playing a role in reducing pollution buildup. Particle dynamics analysis highlighted the importance of considering temporal dynamics and their implications for pollutant pathways, particularly through the swash zone during high tide phases. The study identified primary current patterns near the reef area and emphasized the circular behavior within the water body, affecting corals' susceptibility to bleaching in the southwestern part of Hanauma bay. To understand where oxybenzone concentrations were a threat to wildlife, we created a geographic model that integrated ecological risk assessment with hydrodynamic behavior in a given system, which we designate the Risk Quotient Plume – the geographic area where the concentration is above the threat level for a chemical. The study found high oxybenzone concentrations throughout the bay, threatening coral, fish, and algae populations. Oxybenzone's distribution indicated a serious threat to the entire back reef habitat and a hinderance to coral restoration efforts. The study also emphasizes the need to consider the hydrodynamic behavior of pollutants and their interaction with microplastics in the bay. Overall, the findings provide insights into hydrodynamics and pollutant dispersion in Hanauma Bay, supporting effective pollution management and conservation strategies.

Numerical simulation of velocity distribution and pollution retention in flexible submerged vegetated channel

Vegetation is an important factor that affects the hydrodynamics of river channels. Using hydrodynamic and water quality models in vegetated channels can help better understand the problem of river water pollution. In this paper, the lattice Boltzmann method (LBM) is used to simulate the hydrodynamics of flexible vegetated channels, and the projected area characteristics of flexible vegetation are input into the model to obtain better simulation results for the vertical velocity distribution. At the same time, the random displacement method is used to simulate the transport law of pollutants and calculate the pollutant retention rate under different vegetation projected area characteristics. The results show that both vegetation species and average flow velocity have significant effects on pollutant retention efficiency. This method helps to optimize the selection of species, density, and distribution of river vegetation.

Retention of Phthalates in Wine Using Nanomaterials as Chemically Modified Clays with H20, H30, H40 Boltron Dendrimers.

The presence of phthalic acid esters in wines presents a major risk to human health due to their very toxic metabolism. In this paper, aluminosilicate materials were used, with the aim of retaining various pollutants and unwanted compounds in wine. The pollutants tested were di-butyl and di-ethyl hexyl phthalates. They were tested and detected using the gas chromatography-mass spectrometry (CG-MS) analytical technique. Nanomaterials were prepared using sodium bentonite, and were chemically modified via impregnation using three types of Boltron dendrimers of second, third and fourth generations (NBtH20, NBtH30 and NBtH40). The synthesized nanomaterials were characterized using the Brunauer-Emmett-Teller (BET) method, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. In this paper, two aspects were addressed: the first related to the retention of phthalate-type pollutants (phthalic acid esters-PAEs) and the second related to the protein and polyphenol levels in the white wine of the Aligoté grape variety. The results obtained in this study have a major impact on PAEs in wine, especially after treatment with NBtH30 and NBtH40 (volumes of 250-500 μL/10 mL wine), with the retention of the pollutants being up to 85%.

Advances in ecotechnological methods for diffuse nutrient pollution control: wicked issues in agricultural and urban watersheds

Considerable time and funding have been committed to tackling nonpoint source (NPS) pollution in agricultural and urban watersheds . Notwithstanding all these efforts, the water quality in many AUWs has not significantly improved. Diffuse nutrient pollution involves the movement of these pollutants between soil and water. Excessive diffuse pollution has been accepted as one of the main causes of failure to attain favorable environmental conditions in freshwater systems. Recently, several technologies and practices have been implemented to manage diffuse pollution, namely: a) source reduction, b) pollutant retention over the movement process; c) nutrient recycling, and d) purification and restoration of the eutrophic water bodies. This paper synthesized the existing knowledge of key methods to tackle diffuse pollution from AUWs. Furthermore, the predominant purification mechanisms and impacting factors are explored, allowing a comprehensive and critical understanding of different control strategies to improve the management of diffuse pollution. Therefore, potential approaches for strengthening the performance of control technologies for diffuse pollution treatment and remediation are discussed. Although adopting source reduction strategies (e.g., the “4R” approach: right rate, right time, right source, and right placement of nutrients) could efficiently decrease surface runoff and pollutant levels, they may not stop runoff from entering nearby streams. Consequently, comprehensive treatment of agricultural runoff still requires extra process retention strategies. Overall, the findings of this paper showed that treatment system design and operational and environmental factors played crucial but variable roles in diffuse pollution treatment. Moreover, the results showed that combining or integrating constructed wetlands with other control technologies could enhance the comprehensive purification of diffuse pollution compared to using a single method. This review proposes a systematic approach for diffuse pollution control based on three components (water, soil and microbiota) and maximizing the regulating services of agroecosystems via land use/cover types. The current review contributes to the documentation of existing research trends. It sheds light on diffuse pollution control approaches in AUWs, and further encourages the development of this vital field.

Anion exchange resin/quartz sand bi-layer composite dynamic membranes in ultrafiltration for algae-laden water treatment

Ultrafiltration treatment of algae-laden water is the biggest challenge of membrane fouling. In this study, a bi-layer composite dynamic membrane was constructed by depositing anion exchange resin (AER) and quartz sand on the surface of UF membrane to enhance the separation performance and reduce membrane fouling. AER deposition layers improve contaminants removal and reduce membrane fouling based on retention and ion exchange effect, however, the large porosity results in less than optimal efficiency gains. Deposition of quartz sand on the AER deposit layer significantly enhanced pollutants removal rate and reduced the fouling resistance of the membrane. Compared to AER deposition alone, the bi-layer significantly improved the removal of DOC (20%), UV254 (22%), protein (18%), polysaccharide (13%), MC-LR (11%), GSM (18%) and 2-MIB (3%) and slowed down the development of fouling resistance when the amount of quartz sand deposited reached 68.6 g/m2. As the quartz sand deposition increased to 91.4 g/m2, the presence of a critical value was found, and although the pollutants retention rate increased further, reversible fouling appeared to increase. SEM image analysis of the dense sediment layer traps too much contaminants, resulting in a gel-like layer of contamination that increases membrane fouling.

Road Pavement, Road Pollution, and Sustainability under Climate Change Increased Temperature

This paper presents a multidisciplinary approach to understand the impacts of temperature increase on the retention of particulate pollutants, such as heavy metals and microplastics, by the road pavement material. A soil with a particle size distribution similar to road dust was selected. A Wheel Tracking device was used to assess the permanent deformation behavior of prismatic specimens and the retention of the dust, at controlled temperatures of 40 °C and 60 °C, likely to occur on pavement in the future. The soil representing road pollutants was placed at the top of the slabs prior to the Wheel Tracking Test (WTT), based on the European Standard EN 12697-22:2020. After the WTT, two common methods were used, in order to evaluate the soil retention (pollution accumulation) on road pavement. The results confirm that the viscoelastic behavior of bituminous mixtures under increased temperatures can contribute to particle retention at the pavement. Future studies are needed to understand the phenomena, the retention characteristics by different bituminous mixtures, and the efficiency of pollutants capture. The work opens the opportunity to develop innovative road pavement bituminous mixtures that can reduce the discharge of road particulate pollutants, and have increased resilience and sustainability in extreme weather conditions.

Ventilation and Pollutant Dispersion Analysis in the Uneven Building Arrays along with the Green Roof System

AbstractIn this study, uneven urban streets are explored with different standard deviations (σH = 0–0.6) through numerical simulations. The ventilation and pollutant diffusion conditions are investigated under the combined action between the thermal buoyancy force and mechanical wind force. When the thermal buoyancy is uniformly distributed, the upstream vortex gradually occupies the most area of the flow unit with the increase in σH. Three configurations of green roof systems (roof, leeward, and windward cooling schemes) are assumed to represent different thermal buoyancy distributions in the street canyon. The average air exchange rate and pollutant retention time (τ) are proposed to evaluate the ventilation efficiency and pollutant dispersion condition. The “free airflow” phenomenon occurs and gradually expands with the increase in the standard deviation of each model. The flow structure and pollutant distribution inside the urban canopy are similar in the uniformly heated and leeward cooling scheme. The windward cooling scheme presents the least local retention time in most working conditions. The roof cooling scheme aggravates the pollutant accumulation conditions inside the street canyon. This study can provide some constructive guidelines in the urban planning process and benefit the design of urban greening with different building morphologies.

Adsorbents obtained from recycled polymeric materials for retention of different pollutants: A review

Polymeric waste is an environmental problem, with an annual world production of approximately 368 million metric tons, and increasing every year. Therefore, different strategies for polymer waste treatment have been developed, and the most common are (1) redesign, (2) reusing and (3) recycling. The latter strategy represents a useful option to generate new materials. This work reviews the emerging trends in the development of adsorbent materials obtained from polymer wastes. Adsorbents are used in filtration systems or in extraction techniques for the removal of contaminants such as heavy metals, dyes, polycyclic aromatic hydrocarbons and other organic compounds from air, biological and water samples. The methods used to obtain different adsorbents are detailed, as well as the interaction mechanisms with the compounds of interest (contaminants). The adsorbents obtained are an alternative to recycle polymeric and they are competitive with other materials applied in the removal and extraction of contaminants.

ENVIRONMENTAL POLLUTANTS OF THE RAINWATER DRAINAGE SYSTEM OF MYKOLAIV

The article is devoted to the study of the chemical composition and quantitative volume of pollutants entering the Bug Estuary with the rainwater sewage of Mykolaiv. It is known that sewage from industrial and municipal enterprises poses a threat of a significant additional burden on limited regional water resources. First and foremost, uncontrolled stormwater runoff is a major concern. In Mykolaiv, there are 49 registered stormwater drains, of which 19 are directly discharged into open water bodies. The purpose of the study was to investigate the chemical composition and volume of urban stormwater runoff into the Bug Estuary. The study was based on the results of chemical analyses of water samples from four storm sewers in Mykolaiv, performed in 2022. The materials of chemical analyses of water samples from five storm sewers of Mykolaiv in 1997 were also included. It was proved that phosphates, oil products, and nitrite nitrogen are present in the stormwater runoff from Mykolaiv to the Bug Estuary. The multiplicity of exceedances of the maximum permissible concentrations is: for biological oxygen consumption - 14-37 times; nitrite - 10-39 times; chemical oxygen consumption - 7-18 times. It has been shown that lead, nickel, iron, copper, chromium, and zinc are released into the Bug estuary with rainwater runoff. Excessive pollution of rainwater with suspended solids is associated with contamination of territories with dust, soil, clay, etc. Excessive pollution with oil products and heavy metals is associated with the operation of motor vehicles and industrial enterprises. It has been shown that unauthorized connections of domestic and industrial sewage systems are mostly responsible for some of the substances that pollute stormwater (phosphates, nitrates). Prospects for further research are the study of the sorption capacity of bottom sediments for the retention of pollutants and the assessment of the ecological capacity of the bottom sediments of the Bug estuary..

The impact of operational factors on degradation of formaldehyde as a human carcinogen using Ag3 PO4 /TiO2 photocatalyst.

Background: The International Agency for Research on Cancer (IARC) identified formaldehyde as a carcinogen in 2004, yet formaldehyde is widely used in health care settings and various industries. In recent years, photocatalytic oxidation has been developed as a potential technique for removing pollutants arising from organic chemical agents and consequently promoting the health indices. This study investigated the effect of operational factors in optimizing formaldehyde removal from the air using Ag3 PO4 /TiO2 photocatalyst. Methods: An experimental study was designed to investigate the effect of operational factors on the efficiency of formaldehyde degradation. The variables investigated in this study include pollutant retention time, initial pollutant concentration and relative humidity. Sol-gel method was used to synthesize the nano-composite photocatalyst. An ideal experimental design was carried out based on Box-Behnken design (BBD) with response surface methodology (RSM). The sample size in this study includes all the glasses coated with Ag3 PO4 /TiO2 photocatalyst. Results: The maximum formaldehyde degradation of 32% was obtained at the initial concentration of 2 ppm, 20% relative humidity, and 90 minutes of retention time. Based on the statistical results, the correlation coefficient of the present study for the impact of operational factors on formaldehyde degradation was 0.9635, which means that there is only 3.65% probability of error in the model. Conclusion: The operational factors examined in this study (retention time, relative humidity, and initial formaldehyde concentration) were significantly influential in the degradation efficiency of formaldehyde by the photocatalyst. Due to the high exposure of employees and clients of health and treatment centers to formaldehyde as a carcinogenic substance, the results of this study can be used in ventilation systems to remove environmental pollutants in health care centers and other occupational settings.

Influence of sediment characteristics on long-term hydrology and water quality behaviour during the clogging process of a permeable asphalt

Sustainable urban drainage systems (SUDS) are common solution to address flow discharges, runoff volumes and pollutant concentrations caused by urban expansion and climate change trend. Among them, permeable pavements (PP) effectively manage and treat stormwater. The clogging process of PP has been addressed in previous studies but there is still room for improvement the knowledge about how it affects to their performance in terms of hydrological behaviour and pollutant removal and how it depends on sediment properties. The present study simulates and analyses the behaviour of a permeable asphalt through 47 sediment loading steps tested for six different sediment classes under laboratory conditions. The experiments were performed using permeable asphalt slabs in two laboratory rainfall simulators, measuring reductions in permeability, filtered and runoff flows, and water quality variations in effluents according to sediment loads and rainfall events. The results showed significant reductions of permeability (22–99 %) for sediment surface loads from 1 kg/m2 onwards, except for very fine sediments (<125 μm) (1 %). Permeability recovery after vacuum cleaning varied between 8 % and 100 % of original permeability. Sediment particle size distribution, organic matter content and rain events sequence were key variables influencing the permeability loss and its recovery, and quality of filtrated water. The hydraulic efficiency was high, filtrating almost 100 % of the applied rainfall, whenever the sediment surface load was below 4 kg/m2, above which surface runoff was produced. The efficiency of the slab for pollutant retention was 96 % for COD, 76 % for TN, 79 % for TP, and 98 % for TSS.

Stratification and its consequences in two constructed urban stormwater wetlands

Stratification in constructed urban stormwater wetlands is one of the fundamental physical processes that affect hydrodynamics, transport and fate of stormwater pollutants. Adverse effects of stratification include decreasing pollutant retention capacity, causing the water at lower depths to become anoxic, degrading water quality and increasing stress on the downstream aquatic communities. The current study reports on a comprehensive field monitoring program of stratification and hydrodynamics in two ice-free seasons (May – October) in two constructed urban stormwater wetlands in Calgary, Canada, with different inlet, outlet, morphometric and vegetation designs. Despite their small sizes of 0.5 and 1.2 ha and shallow water depths of 0.8 m, stratification was strong and persistent in the wetlands. The response of stratification and mixing to atmospheric forcings (e.g., air temperature, atmospheric instability, rainfall depth, wind speed) and the impact of design characteristics (inlet/outlet design, water depth, surface area and aquatic vegetation) were examined and discussed. Thermal stratification, defined as a vertical temperature gradient >1 °C/m, was found to be significantly higher (up to ten times) near the inlets and last longer (up to twice) than in the main cells and the outlet basins due to the relatively cold summer inflows. The wetland with twice the permanent water volume and surface area and half the length-to-width ratio had denser submerged aquatic vegetation, higher (by up to 2 °C) water temperature and more severe (up to eight times) thermal stratification. Strong densimetric stratification and low wind stress on the water surface caused hypoxic conditions near the bed, potentially adversely affecting water quality and downstream aquatic communities.

Overlooked Impacts of Urban Environments on the Air Quality in Naturally Ventilated Schools Amid the COVID-19 Pandemic

The density, form, and dimensions of urban morphology are important for healthy living conditions in cities, especially if they are related to the climate and air pollution. Morphology and environmental conditions determine the relationship between open and built space, the width of street spaces, the aerodynamic characteristics of wind currents, albedo, and the retention of pollutants, as well as determining the radiative exchange with the atmosphere. Studies on the COVID-19 pandemic have focused on the assumption of a possible relationship between the spread of the SARS-CoV-2 virus and the presence and concentration of airborne particulate matter (PM10 and PM2.5). This paper focuses on the research of indoor air quality (IAQ) in two schools with naturally ventilated classrooms in Ljubljana, Slovenia. The presence of particulate matter (PM2.5 and PM10) and the concentration of CO2 were studied, along with other microclimatic conditions, e.g., ambient temperature, relative humidity, air pressure, and wind conditions. These were compared and assessed via analysis of variance (ANOVA) and Duncan’s post hoc test. The main concern was to see how effective different ventilation strategies are, as well as how the openings in the classroom impact the concentrations of CO2 relative to the concentrations of PM2.5 and PM10 particles as a side effect of these ventilation strategies. The inconsistent application of recommended COVID-19 ventilation strategies suggests that IAQ in naturally ventilated classrooms is highly determined by individual perceptions of indoor air quality. The results also suggest that the IAQ is significantly affected by the schools’ urban environment; however, this is not considered within the national COVID-19 ventilation recommendations. Future ventilation guidelines for pandemics should also include the urban environment as a risk factor for inadequate IAQ, instead of focusing solely on pathogen characteristics.

Polymer-assisted hydraulic dredging for quality control of stormwater pond sediment and reject water – Influence of polymer choice and its preparation

Hydraulic dredging of stormwater ponds may include on-site dewatering of dredged materials using polymers and geotextile filtration. The choice of polymer and its preparation affect the overall operational effectiveness and the quality of the reject water (filtrate) returned to the stormwater pond. This study examined the resulting particle content as well as nutrient and metal concentrations in the filtrate conducted on hydraulically dredged stormwater sediment that was chemically conditioned and filtered through geotextile. This study investigates how polymer choice and preparation affects the outcome. In total, three types of polymers were tested (powder, emulsion commercial cationic polymers and chitosan), the water (tap water or reclaimed) the polymer was prepared in, and the aging time of the polymer solution. Deviations from manufacturer's instructions on the polymer preparation increased the amount of polymer needed for an optimal conditioning process. In terms of pollutant retention, there was no difference between polymer preparations. In the filter cake there was no discernable difference between conditioned and unconditioned sediment, rather the difference was noticeable on the filtrate. Conditioned stormwater sediment produced a geotextile filtrate with considerably less metal and nutrient content than the unconditioned stormwater sediment.

The optimal choice of environmental tax revenue usage: Incentives for cleaner production or end-of-pipe treatment?

The environmental tax system is effective in pollution abatement. However, levying an environmental tax may be detrimental to economic growth. Reasonable use of environmental tax revenue may achieve both environmental protection and economic growth. This study proposes to earmark environmental tax revenue for pollution treatment. Taking fiscal expenditure theory into consideration, environmental tax revenue usage is divided into transfer expenditure and purchase expenditure. An environmental computable general equilibrium (CGE) model is established to evaluate the effects of environmental tax revenue usage. The optimal choice is to increase the environmental tax rate and simultaneously use tax revenue for cleaner production subsidies and end-of-pipe treatment expenditures. Under the optimal scenario, pollutant retention decreases by 21.45%, and GDP increases by 0.006%. For most regions in China, it is better to raise the environmental tax rate to the middle level of a specified range. Moreover, the government should distribute environmental tax revenue evenly across the expenditure of different environmental protection projects.

DETERMINATION OF HYDRAULIC GRAIN SIZE OF NATURAL AND ARTIFICIAL SORBENTS FOR SIMULATION OF SETTLE FACILITY

In the conditions of progressive contamination of surface sources of water supply and inefficient wastewater treatment when using existing water treatment technologies, the research problem and the justification of the use of sorption materials for the retention of specific pollutants, in particular heavy metal ions and radionuclides, is urgent. The parameters that determine the efficiency of sorbents are indicators of their sedimentation rate. The purpose of the experiments was to determine the sedimentation rate indicators for bentonite and copper ferrocyanide, build sorbent sedimentation graphs, and establish the estimated sedimentation rate of sorbents in the sedimentation tank based on the studied data considering temperature regime. Deposition of the sorbent in settling tanks occurs with the non-stop movement of water at a low speed in the direction from the inlet to the outlet. The experiments are aimed at substantiating the efficiency and criteria of a universal facility, which is able to work equally effectively with sorbents in different aggregate states. The process of sorbent sedimentation in water is characterized by the kinetics of sorbent flakes conglomerates sedimentation. These processes are displayed in the form of deposition kinetics graphs. The experiment used powdered bentonite and a solution of copper ferrocyanide, consisting of yellow blood salt and copper sulphate in a given proportional ratio. In the course of the study the following parameters were determined: the hydraulic grain size of bentonite powdery clay, the dependence of the sedimentation rate on the temperature regime. The liquid layer was divided into layers that show changes in the amount of suspended substances depending on the depth, which made it possible to determine the dimensions of the settling tank, the height of the liquid overflow, which, in turn, made it possible to conduct simulation experiments on virtual machines with a full-scale clarifier-absorber in accordance to geometric parameters.

Analysis of long term water quality variations driven by multiple factors in a typical basin of Beijing-Tianjin-Hebei region combined with neural networks

Water environment can be affected by multiple natural and human factors.This study aimed to explore the impacts on water quality from various driving factors including land use, landscape, social economy and climate in a typical basin of Beijing-Tianjin-Hebei Region combined with neural networks like self-organizing map and back propagation artificial neural network based on the water quality monitoring data.And redundancy analysis as well as gray correlation analysis were also adopted to explore the relationships between water quality and landscape indices as well as socioeconomic factors, respectively. The results showed that different land uses had different impacts on water quality. Agricultural additions in cropland had a great impact on surrounding water environment. The forest and grassland purified water to some degree, while the vegetation purification became weaker when there was serious pollution. The fragmentated landscape patches with high patch density caused by human activities also worsened water quality because its retention of pollutants was weakened. Besides, the per capita disposable income of rural residents and the per capita disposable urban income had the highest correlation degrees with most water quality indexes in all socioeconomic factors. In addition, temperature rise would promote dissolved oxygen consumption and eutrophication. Increasing precipitation brought pollutants into water via rainfall contains, nutrient transportation and soil erosion. The main conclusions were that both agricultural activities and urban development had impacts on water environment, and the vegetation purification became less obvious in heavily polluted areas. In addition, the rising temperature and precipitation disturbed water quality under the background of global warming. This study is helpful for water pollution management and it will give enlightenment for the water environment protection under the combining effects of human disturbance, economic development and climate change.

Investigating the influences of concave depths on stormwater runoff and pollution retention of urban grasslands.

In this study, scale-based runoff plots of concave grasslands were designed and simulated rainfall experiments were conducted to investigate their retention effectiveness for runoff volume and pollutant loads, and to analyze the influences of concave depths on runoff and pollution retention of grasslands. Results showed that mean time to runoff of concave grasslands was 88.5 minutes, which was 5.3 times than that of flat grassland. Average peak flow rate of concave grasslands was reduced by 36.2% compared with flat grassland. Concaved grasslands averagely retained 58.2% of stormwater runoff. Deeper concave depths significantly increased runoff detention and retention performance of grasslands. Total suspended solids (TSS) load reduction rates of concave grasslands were ranged from 50.8% to 97.3%. Total nitrogen (TN) load reduction rate was 49.8% for concave depth of 10 cm. Total phosphorus (TP) load reduction rates were 45.0% and 93.9% for grasslands with 5 cm and 10 cm concave depths, respectively. Pollution load reduction rates of TSS, TN and TP enhanced along with the increase in concave depths. The estimated minimum area ratios of upslope impervious surface to grasslands of 5 cm and 10 cm concave depths were approximately 1:1 under 20 mm rainfall events, and 38:1 under 5 mm rainfalls, respectively.

Environmentally-stable eco-friendly pectin-silica bio-hybrid foams for soil remediation

Here we present a new class of hybrid material composed of a polysaccharide macroporous core surrounded by a thin silica layer as new adsorption platforms for the retention of organic pollutants in soil media. The core-shell hybrid foams were fabricated by ice-templating to create highly anisotropic pectin foams, followed by vapor phase silica deposition. The structural stability of the hybrid foams was tested in compression, reaching a Young's Modulus up to 5 MPa, but also, and more importantly, in direct contact with wet soils over more than one month. Hybrid foams showed a sorption capacity for a toxic dye nearly two orders of magnitude higher than the surrounding soils. Altogether, these hybrid foams combine all chemical, structural and functional properties required to be effective materials for soil depollution and, thanks to their easy-recovery, should compete with common particulate sorbents.