Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 943
Filtrar
1.
Sci Rep ; 13(1): 171, 2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36599910

RESUMO

Wheels play an important role in mobile robotics, wheelchairs and vehicles and represent an ideal solution for traversing rigid ground due to higher efficiency. Through traversing loose soil, the rigid wheels lose traction because of sinking and higher slip ratios. Therefore, the study suggests a new rigid wheel with a distinguished perimeter to increase mobility demands to overcome the previous inevitable concerns and clarifies its full detailed design. The lateral undulation locomotion of snakes inspired the author to introduce a new simple and affordable wheel design. The optimum values of the limbless creature movement on the sand are reflected in the geometrical parameters of the wheel, amplitude to wavelength ratio. In addition, the experimental work assessed the traveling performance of the fabricated wheel on the rigid ground and the sandy soil. The attained net traction and slip ratios approach the values of more complicated, expensive and heavier wheels that were used in farming and planetary exploration. Consequently, the wheel enables the wheeled locomotive to do missions on sandy soil with no trouble.


Assuntos
Robótica , Cadeiras de Rodas , Solo , Locomoção , Areia
2.
Sci Rep ; 13(1): 981, 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36653389

RESUMO

The tailings pond is a dangerous source of man-made debris flow with high potential energy. The oxidative acidification of tailings may cause the instability of the pond and induce serious safety accidents. The influence of oxidation and acidification degree on macro mechanical properties of tailings is discussed from the aspects of mineral composition and microstructure. The results show that as the degree of oxidation and acidification of tailings sand increases, the overall structural performance and load-bearing capacity decrease, and its cohesion (c) and internal friction angle (φ) show a decreasing trend. In fact, the engineering properties of tailings with different oxidation and acidification degrees are dominated by the physicochemical composition and structural characteristics. On the one hand, as the degree of oxidation increases, acidic substance will neutralize with CaCO3 and CaMg(CO3)2, resulting in the loss of cemented substance and the decrease of cementation force between tailing sand particles as well as the gradual destruction of the integrity of tailing sand. On the other hand, the increase of oxidation and acidification degree of tailing sand leads to a gradual reduction of outline (2D) fractal dimension and gray surface (3D) fractal dimension of surface laminated structure as well as the obvious reduction of laminated structure and its roughness of tailings sand.


Assuntos
Minerais , Areia , Humanos , Fenômenos Químicos , Oxirredução , Concentração de Íons de Hidrogênio
3.
Sci Rep ; 13(1): 719, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36639430

RESUMO

The failure of civil engineering structures especially buildings by severe cracks, partial, or complete collapse have kept the natives of communities in Aguamede and Ehamufu (Southeastern Nigeria) communities in a bothered state. Detailed geotechnical techniques and X-ray diffraction analysis were applied to investigate the soil samples from the study area. Geotechnical results revealed that the soil of the area have high clay content (62.78-82.37%), high liquid limit (48-54%) with a plasticity index of 20-28%, high moisture content (25.06-27.28%) and low permeability of 2.21 × 10-8-1.74 × 10-6 (m/sec) which hinders drainage. Maximum dry density values were in the range of 1.73-1.98(g/cm3) with an optimum moisture content of 17.5-19.8% and average specific gravity of 2.5 (mg/m3). Shear strength test revealed high cohesion (32-36.4 KN/m2) to low angle of intergranular friction (10-12°). Coefficient of consolidation ranges from 0.04 to 0.94 m2/year were observed. Coefficient of volume compressibility values were in the range of 0.00012-0.00028 m2/kN and showed that the soils are highly susceptible to compression as the foundations are underlain by an inadequate soil layer that is vulnerable to settlement in amount ranging from 0.553-0.654 mm/year at load pressure of 400 kN/m2. X-ray diffraction analysis revealed that the mineralogy of soil in the study area consist of quartz (89-89.7%) and kaolinite (10.3-11%). Statistical analyses showed that specific gravity, cohesion, clay, silt, NMC, PI, sand, LL and phi have strong interrelation in the correlation table. Comparing the geotechnical parameters from the study area with the Nigerian specification for constructions, it is shown that the study area has poor foundation materials.


Assuntos
Areia , Solo , Argila , Nigéria , Solo/química , Permeabilidade
4.
Sci Rep ; 13(1): 1226, 2023 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-36681731

RESUMO

The exploration and development of the dual-provenance lower assemblage of the Yanchang Formation in the Jiyuan area has progressed rapidly. At the intersection of this bidirectional provenance system, a complex and variable spatial combination of sand bodies formed, resulting in significant structural heterogeneity in the development and distribution of reservoirs. Based on previous studies, this paper combines core data and logging data with a large number of analytical tests and production performance data to carry out research on the Chang 82-Chang 9 reservoir group in the lower assemblage of the Yanchang Formation in the Shijiawan-Buziwan area. Based on the analysis of sedimentary conditions, the sand body development pattern at the intersection of the bidirectional sedimentary system in the study area was analysed by stepwise dissection of the sand body architecture. After the types and characteristics of the 4th- to 5th-level architectural elements were determined, the spatial distribution of the combinations of these elements was assessed and combined with logging discriminant analysis and geometric shape prediction methods to identify a 'prism' architectural distribution pattern. The architectural elements are connected with the distribution of diagenetic facies, the spatial distribution patterns of different types of diagenetic facies under the constraints of the architecture are summarized by region, and the locations of potential favourable reservoir development are discussed. The results show that the degree of superposition and combination of the eight skeletal architectural elements in the target layers gradually deteriorate from the bottom to the top. In addition, the development scale and degree of architectural elements in the braided river delta system in the west are better than those in the meandering river delta system in the east. In the different sedimentary areas, the spatial combination styles of the architectural elements are quite different, and the combination of these elements gradually changes from a combination of braided channels (FA1) and abandoned channels (FA2) to a combination of underwater distributary channels (FA4). Matching of the distribution of diagenetic facies with the distribution of architectural elements reveals that the diagenetic facies dominated by intergranular pores and dissolution pores (associated with good reservoir physical properties) are usually found at the bottom or in the lower to middle parts of the skeletal architectural elements.


Assuntos
Sedimentos Geológicos , Areia , Humanos , Sedimentos Geológicos/química , Facies , Rios/química
5.
Proc Biol Sci ; 290(1990): 20221786, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36629097

RESUMO

Sand mining, which has tripled in the last two decades, is an emerging concern for global biodiversity. However, the paucity of sand mining data worldwide prevents understanding the extent of sand mining impacts and how it affects wildlife populations and ecosystems, which is critical for timely mitigation and conservation actions. Integrating remote sensing and field surveys over 14 years, we investigated mining impacts on the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) in Dongting Lake, China. We found that sand mining presented a consistent, widespread disturbance in Dongting Lake. Porpoises strongly avoided mining sites, especially those of higher mining intensity. The extensive sand mining significantly contracted the porpoise's range and restricted their habitat use in the lake. Water traffic for sand transportation further blocked the species's river-lake movements, affecting the population connectivity. In addition, mining-induced loss of near-shore habitats, a critical foraging and nursery ground for the porpoise, occurred in nearly 70% of the water channels of our study region. Our findings provide the first empirical evidence of the impacts of unregulated sand extractions on species distribution. Our spatio-temporally explicit approach and findings support regulation and conservation, yielding broader implications for sustainable sand mining worldwide.


Assuntos
Toninhas , Areia , Animais , Ecossistema , Cetáceos , Toninhas/fisiologia , Lagos , China , Mineração
6.
Huan Jing Ke Xue ; 44(1): 405-414, 2023 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-36635828

RESUMO

This study used both the element occurrence form analysis and the chronic health risk assessment method to investigate the accumulation characteristics of heavy metals in the soil-crop system and the health risk assessment of agricultural products in northeastern Yunnan, which is a typical area of Southwest China where heavy metals are enriched in soil. Based on the study of 1137 groups of agricultural products and corresponding root soils, the results showed that the soil cadmium (Cd) and lead (Pb) in the lead-zinc ore concentration area were higher than the risk-intervention values of the "Soil Environmental Quality Risk control standard for soil contamination of agricultural land" (GB 15618-2018), whereas the soil Cd in the other parent material areas was within the screening-intervention buffer zone, and Pb was below the minimum risk-screening value. According to the National Food Safety Standard of China (GB 2762-2017), the heavy metal Cd in potatoes and soybeans in the area seriously exceeded the standard, the heavy metal Pb in tartary buckwheat and walnut exceeded the limit value, and the exceeding rate of heavy metal Cd in crops from these parent material areas showed: clastic rock>basalt>lead-zinc ore>carbonate ≈ Quaternary sedimentary>sand (mud) rock. According to the U.S. Environmental Protection Agency's assessment method for the chronic health risk of heavy metal intake by humans, the grains and potatoes, staple foods, and fruits had low chronic health risks of heavy metal intake. Agricultural products from the parent material area of clastic rock, sand (mud) rock, Quaternary sedimentary, and lead-zinc ore concentration showed health risks; with the change in soil physical and chemical properties and the increase in the types of edible crops, the risk will gradually increase. Based on this research, it is urgent to carry out real-time monitoring of agricultural products in the area.


Assuntos
Metais Pesados , Poluentes do Solo , Humanos , Solo/química , Cádmio/análise , Areia , Chumbo/análise , China , Poluentes do Solo/análise , Metais Pesados/análise , Zinco , Medição de Risco , Produtos Agrícolas/química , Monitoramento Ambiental
7.
Braz J Biol ; 82: e269137, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36629548

RESUMO

Soil is the base of any ecosystem since it conserves nutrients and water for plant roots including agriculture and plantations. In dry and semi-arid places across the world, including the UAE, sandy soils are common. Their fertility is extremely low, and production is hampered by a number of agronomic challenges. Soil conditioner sources like bentonite and chicken manure might be used to improve the poor sandy soil attributes and hence boost soil productivity. From November 2019 to March 2020, an experiment was conducted to investigate the growth rates of Bougainvillea following bentonite and chicken manure amendments to sandy soil taken from Lehbab, Dubai. Bougainvillea was evaluated for its plant height (cm), max length of primary branch (cm), the number of leaves per plant, number of secondary branches, shoot weight (g), root length (cm), root weight (g), root/shoot ratio, chlorophyll contents, and chlorophyll a* and b*. In this experiment, a complete randomized design (CRD) with five treatments was used (10 replications per treatment). According to the findings, bentonite and chicken manure additions considerably influence the productive properties of sandy soil, as indicated by Bougainvillea growth. Additionally, the research suggests that Bougainvillea may be efficiently planted with 10% bentonite and 15% chicken manure applied to sandy soil, resulting in the healthiest plants compared to other amendments.


Assuntos
Bentonita , Solo , Animais , Galinhas , Clorofila A , Ecossistema , Esterco , Aves Domésticas , Areia
8.
Sci Rep ; 13(1): 397, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36624135

RESUMO

The highly acid sulfate Rangsit soil series of Rangsit, Pathum-Thani district, Thailand poses a major problem for agriculture in the area. Water hyacinth is a naturally occurring weed that can grow aggressively, causing eutrophication and leading to many severe environmental impacts. Here, through the pyrolysis process, we convert water hyacinth to biochar and use it for acid soil amendment. We found the ratio between biochar, soil, and sand suitable for the cultivation of water convolvulus to be 50 g of biochar, 400 g of soil, and 100 g of sand (1:8:2). This soil mixture improved the pH of the soil from 4.73 to 7.57. The plant height of the water convolvulus grown in the soil mixture was the greatest at 20.45 cm and the plant weight with and without roots was greatest at 2.23 g and 2.52 g, respectively. Moreover, we demonstrated the dominance and high abundance of Bacillus among the community in soil with biochar amendment. Here we provide the first assessment of the appropriate amount of water hyacinth-derived biochar for mitigation of soil acidity and promotion of optimal water convolvulus growth. Moreover, biochar can optimally modify soil bacterial communities that benefit plant development.


Assuntos
Eichhornia , Solo , Areia , Carvão Vegetal , Concentração de Íons de Hidrogênio
9.
J Environ Manage ; 328: 116947, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36508977

RESUMO

Large-scale ecological restoration programs have been initiated globally with the aim of combating desertification and improving ecosystem services, especially for sand fixation service (SF) in arid and semi-arid regions. However, the effectiveness of ecological restoration in the radiation benefit of SF, such as improving air quality, remains not well known. In this study, we selected Xilingol as the study area, investigated the dynamics of SF, and quantified the radiation benefit of SF in downwind areas by employing PM10 concentration as the proxy. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was applied to assess the response of radiation benefit to ecological restoration by designing land use scenarios. Results showed that the SF in Xilingol increased with fluctuation at an average rate of 0.27%/year from 2000 to 2018. Under the effect of ecological restoration, the radiation benefit in the downwind regions was substantially improved, as manifested by a 104.22 µg/m3 reduction in PM10 concentration. The changes in radiation benefit varied greatly across space, and northern and southern Xilingol were hot spots for increased radiation benefit. Based on regional disparity in benefit level, this work could provide a reference to make differentiated cross-regional ecological compensation schemes at the national level.


Assuntos
Ecossistema , Areia , China , Clima Desértico , Conservação dos Recursos Naturais
10.
J Environ Manage ; 328: 117005, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36508983

RESUMO

Potential new sources of phosphorus (P) fertilizer are the recovered P from livestock wastewater through chemical precipitation and the ash from combusting animal manures. Although most of the research on P losses from conservation tillage include high water-soluble P compounds from commercial fertilizer sources, information on the use of non-conventional, low water-soluble, recycled P sources is scarce. Particularly for sandy soils of the United States (US) Southeastern Coastal Plain region, research driven information on P loss into the environment is needed to determine recommendations for a direct use of new recycled P sources as crop P fertilizers. The objective of this study is to investigate the potential P runoff from sandy soils under conservation tillage, fertilized with recovered P from liquid swine manure and turkey litter ash in comparison with commercial P fertilizer triple superphosphate (TSP). The field study included two typical sandy soils of the US Southeastern Coastal Plain region, the Noboco and Norfolk. Simulated rain corresponding to the annual 30-min rainfall in the study site (Florence County, South Carolina) was applied to plots treated with recovered P from liquid swine manure, turkey litter ash, and TSP, including a control with no P added. The runoff was monitored and sampled every 5 min during the test and composite soil samples were collected from the top (0-15 cm) and subsurface (15-30 cm) soil layers in each plot. Laboratory analyses were conducted to quantify both total P (TP) and soluble reactive P (SRP) in runoff samples, and the soil test P in the soil layers. Two-way analyses of variances show significant treatment effects on both TP and SRP runoff. The quantities of SRP runoff from plots treated with the recovered P from swine manure and turkey litter ash represent respectively 1% and 7-8% of SRP runoff from plots treated with TSP. Hence, the use of the recovered P materials as crop P fertilizers through surface broadcast application present less environmental risks compared to commercial TSP.


Assuntos
Fósforo , Solo , Animais , Suínos , Fósforo/análise , Fosfatos , Fertilizantes/análise , Areia , Esterco , Movimentos da Água , Chuva , Agricultura
11.
Sci Total Environ ; 862: 160773, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36509275

RESUMO

Levofloxacin (LEV) is prone to be retained in aquifers due to its strong adsorption affinity onto sand, thus posing a threat to groundwater quality. In-situ injection technology for remediating LEV-contaminated soil and groundwater is still challenging owing to the lack of appropriate remedial agents. Herein, two novel multi-component porous covalent-organic polymers (namely, SLEL-1 and SLEL-2) with alkyl chains were constructed through Schiff-base reactions to adsorb LEV from an aqueous solution, in which the kinetics, isotherms, influenced factors were investigated. Plausible adsorption mechanisms were proposed through characterization and experimental analysis, including pore filling effect, π-π electron-donor-acceptor (EDA) interaction, hydrogen bonding force, hydrophobic-hydrophobic interaction as well as electrostatic force. In addition, response surface methodology (RSM) revealed the treatment optimization and reciprocal relationship within multi-variables. Furthermore, taking advantage of favorable dispersion and outstanding competitive behavior, SLEL-1 was established as an in-situ adsorptive agent in dynamic saturated columns on a laboratory scale to investigate the removal of LEV from water-bearing stratum. Overall, the findings of this work provided an insight into the fabrication of SLELs as long-term mobile and reusable adsorptive agents for practical in-situ applications in the future.


Assuntos
Levofloxacino , Poluentes Químicos da Água , Levofloxacino/análise , Areia , Porosidade , Polímeros , Adsorção , Poluentes Químicos da Água/química
12.
Sci Total Environ ; 858(Pt 3): 160066, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36356776

RESUMO

Sulfide-induced reduction (sulfidization) of arsenic (As)-bearing Fe(III) (oxyhydro)oxides may lead to As mobilization in aquifer systems. However, little is known about the relative contributions of sulfidization and non-sulfidization of Fe(III) (oxyhydro)oxides reduction to As mobilization. To address this issue, high As groundwater with low sulfide (LS) and high sulfide (HS) concentrations were pumped through As(V)-bearing ferrihydrite-coated sand columns (LS-column and HS-column, respectively) being settled within wells in the western Hetao Basin, China. Sulfidization of As(V)-bearing ferrihydrite was evidenced by the increase in dissolved Fe(II) and the presence of solid Fe(II) and elemental sulfur (S0) in both the columns. A conceptual model was built using accumulated S0 and Fe(II) produced in the columns to calculate the proportions of sulfidization-induced Fe(III) (oxyhydro)oxide reduction and non-sulfidization-induced Fe(III) (oxyhydro)oxide reduction. Fe(III) reduction via sulfidization occurred preferentially in the inlet ends (LS-column, 31 %; HS-column, 86 %), while Fe(III) reduction via non-sulfidization processes predominated in the outlet ends (LS-column, 96 %; HS-column, 86 %), and was attributed to the metabolism of genera associated with Fe(III) reduction (including Shewanella, Ferribacterium, and Desulfuromonas). Arsenic was mobilized in the columns via sulfidization and non-sulfidization processes. More As was released from the solid of the HS-column than that of the LS-column due to the higher intensity of sulfidization in the presence of higher concentrations of dissolved S(-II). Overall, this study highlights the sulfidization of As-bearing Fe(III) (oxyhydro)oxides as an important As-mobilizing pathway in complex As-Fe-S bio-hydrogeochemical networks.


Assuntos
Arsênio , Compostos Férricos , Areia , Sulfetos , Óxidos , Compostos Ferrosos
13.
J Environ Sci (China) ; 126: 734-741, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36503798

RESUMO

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition. In this study, a synthesized chemical manganese dioxide (MnO2)-coated quartz sand (MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn2+. We demonstrated a manganese-oxidizing bacterium, Pseudomonas sp. QJX-1, could oxidize Mn2+ to generate BioMnOx using humic acids (HA) as sole carbon source. The coaction of MnQS, QJX-1, and the generated BioMnOx in simultaneously removing caffeine and Mn2+ in the presence of HA was evaluated. We found a synergistic effect between them. MnQS and BioMnOx together significantly increased the caffeine removal efficiency from 32.8% (MnQS alone) and 21.5% (BioMnOx alone) to 61.2%. Meanwhile, Mn2+ leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx, which was beneficial for continuous contaminant removal and system stability. Different degradation intermediates of caffeine oxidized by MnQS and BioMnOx were detected by LC-QTOF-MS analysis, which implied that caffeine was oxidized by a different pathway. Overall, this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.


Assuntos
Água Potável , Compostos de Manganês , Manganês , Substâncias Húmicas , Carbono , Bactérias , Areia , Preparações Farmacêuticas
14.
Environ Sci Technol ; 57(1): 139-149, 2023 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-36516361

RESUMO

Polar biotransformation products have been identified as causative agents for the eventual increase in genotoxicity observed after the bioremediation of PAH-contaminated soils. Their further biodegradation has been described under certain biostimulation conditions; however, the underlying microorganisms and mechanisms remain to be elucidated. 9,10-Anthraquinone (ANTQ), a transformation product from anthracene (ANT), is the most commonly detected oxygenated PAH (oxy-PAH) in contaminated soils. Sand-in-liquid microcosms inoculated with creosote-contaminated soil revealed the existence of a specialized ANTQ degrading community, and Sphingobium sp. AntQ-1 was isolated for its ability to grow on this oxy-PAH. Combining the metabolomic, genomic, and transcriptomic analyses of strain AntQ-1, we comprehensively reconstructed the ANTQ biodegradation pathway. Novel mechanisms for polyaromatic compound degradation were revealed, involving the cleavage of the central ring catalyzed by Baeyer-Villiger monooxygenases (BVMO). Abundance of strain AntQ-1 16S rRNA and its BVMO genes in the sand-in-liquid microcosms correlated with maximum ANTQ biodegradation rates, supporting the environmental relevance of this mechanism. Our results demonstrate the existence of highly specialized microbial communities in contaminated soils responsible for processing oxy-PAHs accumulated by primary degraders. Also, they underscore the key role that BVMO may play as a detoxification mechanism to mitigate the risk posed by oxy-PAH formation during bioremediation of PAH-contaminated soils.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Poluentes do Solo , Areia , RNA Ribossômico 16S/genética , Biodegradação Ambiental , Microbiologia do Solo , Solo
15.
Chemosphere ; 313: 137512, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36495971

RESUMO

Knowledge of the fate and transport of nanoscale zero-valent iron (nZVI) in saturated porous media is crucial to the development of in situ remediation technologies. This work systematically compared the retention and transport of carboxymethyl cellulose (CMC) modified nZVI (CMC-nZVI) and sulfidated nZVI (CMC-S-nZVI) particles in saturated columns packed with quartz sand of various grain sizes and different surface metal oxide coatings. Grain size reduction had an inhibitory effect on the transport of CMC-S-nZVI and CMC-nZVI due to increasing immobile zone deposition and straining in the columns. Metal oxide coatings had minor effect on the transport of CMC-S-nZVI and CMC-nZVI because the sand surface was coated by the free CMC in the suspensions, reducing the electrostatic attraction between the nZVI and surface metal oxides. CMC-S-nZVI displayed greater breakthrough (C/C0 = 0.82-0.90) and higher mass recovery (84.9%-89.3%) than CMC-nZVI (C/C0 = 0.70-0.80 and mass recovery = 70.9%-79.6%, respectively) under the same experimental conditions. A mathematical model based on the advection-dispersion equation simulated the experimental data of nZVI breakthrough curves very well. Findings of this study suggest sulfidation could enhance the transport of CMC-nZVI in saturated porous media with grain and surface heterogeneities, promoting its application in situ remediation.


Assuntos
Ferro , Nanopartículas Metálicas , Porosidade , Areia , Quartzo , Carboximetilcelulose Sódica
16.
Water Res ; 230: 119494, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36571965

RESUMO

Micropollutants (MPs), such as pharmaceuticals and antibiotics, are present in the environment at low concentrations (ng/L-µg/L). A constructed wetland (CW) is a nature-based wastewater treatment technology, which can be used to remove MPs from wastewater treatment plant effluent. This study aimed to improve MP removal of CWs by optimizing the design of batch-operated CW. Three pilot-scale CWs were built to study the effect of two design-features: the use of a support matrix (a mixture of bark and biochar) and continuous aeration. The use of bark-biochar as support matrix increased the removal of 11 of 12 studied MPs compared to the CW filled with conventional material sand. The highest improved removal by the addition of bark-biochar was more than 40% (median) for irbesartan, carbamazepine, hydrochlorothiazide and benzotriazole. Aerating the bed of the bark-biochar CW did not change MP removal. Besides, the presence of bark-biochar also enhanced the removal of total nitrogen during 10 months of operation, but no improvement was observed on the total organic carbon and total phosphorus removal. Considering the application in a batch-operated CW, MP removal can be greatly enhanced by replacing sand with bark-biochar that will act as MP adsorbing matrix.


Assuntos
Eliminação de Resíduos Líquidos , Áreas Alagadas , Areia , Nitrogênio/análise
17.
J Environ Manage ; 328: 116971, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36516708

RESUMO

For the in-situ remediation of the contaminated subsurface environment, the injection of nutrients and microorganisms changes chemical and physical conditions, which control the delivery and immobilization of microorganisms. We investigated the injection strategy for effective bacterial delivery in a bioaugmentation scheme by controlling ionic strength (IS) and pore-water velocity (v). A set of bacterial transport tests was conducted using the saturated sand column to mimic the saturated subsurface environment. The effectiveness of the injection strategies was evaluated by applying solutions with different ionic strengths into the sand column with different pore-water velocities. The deposition and delivery of bacteria through the sand column were analyzed using the first-order deposition model. The deposition and delivery of bacteria injected by various strategies were numerically simulated considering the variable deposition rate. The breakthrough curves from column experiments revealed that the bacterial deposition on the sand surface was increased by an increase in the ionic strength and by a decrease in the pore-water velocities. The rates of bacterial deposition (k1) on sand could be determined as a function of ionic strength and pore-water velocity, and it was applicable to simulate the delivery of bacteria under dynamic groundwater conditions. The numerical case study considering various injection strategies showed that the nutrient concentration controlled the bacterial delivery to the target area more significantly than the injection flow rate. Injection of bacterial solution with lower nutrient concentration could be increased the deposited bacterial concentration at the target point (Stp) by 6.2-7.1 times higher. Short pulse injection with a high injection rate decreased Stp by 67-78%. The efficiency of bacterial delivery (Ed) could be increased three times higher by lowering nutrient concentration in the injection solution. The process of evaluating the efficiency of bacterial delivery could be a prominent approach to determining the injection strategy for in-situ remediation considering variable conditions of a contaminated site.


Assuntos
Areia , Água , Água/química , Concentração Osmolar , Porosidade , Dióxido de Silício
18.
J Environ Manage ; 328: 116943, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36516715

RESUMO

Biochar is widely used as a soil amendment due to its environmental friendliness and convenient availability. It is believed that the presence of biochar in porous media can influence the transport of colloidal and solute contaminants. In this study, different mass ratios of biochar were added to packed sand with a rough or smooth surface to determine the significance of biochar on the retention and release of silver nanoparticles (AgNPs). The results showed that biochar reduced the transport of AgNPs in rough and smooth sands under different solution conditions. A small amount of biochar (0.1-1% in mass percentage) can significantly enhance the retention of AgNPs due to the alteration in collector surface roughness and chemical heterogeneity that potentially reduce the energy barrier for retention. Furthermore, the retention of AgNPs in rough sand was always higher than that in smooth sand under the same experimental conditions. The presence of biochar also produced nonmonotonic retention of AgNPs mainly due to the changes in collector surface roughness. Additionally, the AgNPs retention associated with biochar tended to be irreversible due to the charge heterogeneity, while the reversible retention could mainly occur on a rough sand surface via shallow primary minima. This work highlights the significance of collector surface roughness that needs to be considered in the process of biochar amendment for practical applications to effectively immobilize colloidal contaminants in soil or groundwater.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Areia , Nanopartículas Metálicas/química , Prata/análise , Porosidade , Propriedades de Superfície , Solo
19.
Sci Rep ; 12(1): 20906, 2022 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-36463313

RESUMO

Adsorption desorption is an important behavior affecting the migration of phenanthrene in soil. In this study, three typical soils of loess, silts and silty sand in Guanzhong Basin, Shaanxi Province, China were used as adsorbents. Batch equilibrium experiments were carried out to study the adsorption desorption kinetics and isotherm of phenanthrene in different soils. Response surface method (RSM) was used to study the effects of temperature, pH, phenanthrene concentration and organic matter content on soil adsorption of phenanthrene. The results showed that after adsorption, the outline of soil particles became more blurred and the degree of cementation increased. The kinetic adsorption of phenanthrene by soil conforms to the quasi second-order kinetic model, and the adsorption desorption isotherm is nonlinear and conforms to the Freundlich model. Due to the difference of soil properties, the adsorption amount of phenanthrene by soil is loess > silty sand > silts. The thermodynamic results show that the adsorption of phenanthrene by soil is spontaneous and endothermic, and the desorption is spontaneous and exothermic. Through RSM, the interaction between phenanthrene concentration and soil organic matter in Loess and silts is significant, and the interaction between temperature and soil organic matter in silty sand is significant. Among the four factors affecting the adsorption rate of loess, silts and silty sand, soil organic matter is the most significant. The theoretical optimum adsorption rates of loess, silts and silty sand are 98.89%, 96.59% and 93.37% respectively.


Assuntos
Fenantrenos , Solo , Adsorção , Areia
20.
Proc Natl Acad Sci U S A ; 119(49): e2212447119, 2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36459638

RESUMO

Dental wear due to ingestion of dust and grit has deleterious consequences. Herbivores that could not wash their food hence had to evolve particularly durable teeth, in parallel to the evolution of dental chewing surface complexity to increase chewing efficacy. The rumen sorting mechanism increases chewing efficacy beyond that reached by any other mammal and has been hypothesized to also offer an internal washing mechanism, which would be an outstanding example of an additional advantage by a physiological adaptation, but in vivo evidence is lacking so far. Here, we investigated four cannulated, live cows that received a diet to which sand was added. Silica in swallowed food and feces reflected experimental dietary sand contamination, whereas the regurgitate submitted to rumination remained close to the silica levels of the basal food. This helps explain how ruminants are able to tolerate high levels of dust or grit in their diet, with less high-crowned teeth than nonruminants in the same habitat. Palaeo-reconstructions based on dental morphology and dental wear traces need to take the ruminants' wear-protection mechanism into account. The inadvertent advantage likely contributed to the ruminants' current success in terms of species diversity.


Assuntos
Areia , Desgaste dos Dentes , Feminino , Bovinos , Animais , Ruminantes , Poeira , Dióxido de Silício , Desgaste dos Dentes/veterinária
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...