ABSTRACT
Petroleum hydrocarbons as pervasive pollutants pose a significant threat to soil ecology and human health. Surfactant washing as an established technique can effectively remediate soils contaminated by hydrocarbons. Biosurfactants, which combine the properties of surfactants and environmental compatibility, have attracted increasing interest. However, due to the high production cost of biosurfactants, their practical application is restricted. This study addressed these limitations by selecting two biosurfactants, ß-cyclodextrin (C1) and sodium carboxymethyl cellulose (C2), and developed a promising cleaning agent formula through compounding and the addition of suitable additives. When the volume ratio of C1 to C2 was 8:2 and an 8 g/L mixture of sodium humate and sodium carbonate electrolyte was added, the surfactant system's surface tension reached a minimum, yielding optimal oil removal. The formation and synergistic behaviour of mixed micelles of surfactants were explained using ideal solution theory and the Rubingh model. By optimising the oil washing process parameters - normal temperature of 25 °C, pH 11, washing time of 2 h, solid-liquid ratio of 1:5, and oscillation frequency of 200 r/min - the oil removal rate achieved 76%. This cleaning agent, characterised by low production cost, straightforward application, environmental compatibility, and rapid, significant cleaning effect, shows potential for field-scale purification of petroleum-contaminated soil.
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Objective: To evaluate the effectiveness of different acupuncture treatments for mammary gland hyperplasia (MGH) using a network meta-analysis. Methods: Several databases were searched without language restrictions from 2000 to February 2023, including PubMed, Embase, Web of Science, Cochrane Library, China Science and Technology Journal Database, China Biology Medicine Database, Wanfang Database, China National Knowledge Infrastructure Database, and other professional websites and gray literature. Inclusion criteria were adult women diagnosed with MGH; intervention measures included acupuncture and related therapies; the control group was treated with simple drugs; and the research type was a randomized controlled trial (RCT). The primary outcomes were treatment effectiveness and estradiol and progesterone levels. Secondary outcomes were breast lump size and visual analog scale (VAS) score of breast pain. Exclusion criteria were studies unrelated to MGH, incorrect study populations, control measures or interventions, incomplete data, non-RCTs, case reports, and animal experiments. Cochrane tools were used to assess the risk of bias. The R software (x64 version 4.2.1), Review Manager 5.3 software and STATA 16.0 software were used for data analysis. Results: Following a rigorous screening process, data extraction, and quality assessment, 48 eligible RCTs encompassing 4,500 patients with MGH and 16 interventions were included. The results indicated that acupuncture, alone or in combination with traditional Chinese or Western medicine, had better therapeutic effects than conventional therapy. In terms of effectiveness, warm needle acupuncture was the best choice (94.6%). Bloodletting pricking was the most effective method (85.7%) for lowering progesterone levels. Bloodletting pricking was the most effective method (98.3%) for lowering estradiol levels. Manual acupuncture combined with traditional Chinese medicine was the most effective (74.5%) treatment to improve the size of the breast lump. Warm needle acupuncture was the most effective (69.8%) in improving the VAS score. Conclusion: Acupuncture therapy was more effective in treating MGH than drug therapy alone, and warm needle acupuncture and bloodletting pricking were the two best options. However, larger sample sizes and high-quality RCTs are required.
ABSTRACT
Microplastics (MPs) are emerging contaminants found globally. However, their effects on soil-plant systems in salt-affected habitats remain unknown. Here, we examined the effects of polyethylene (PE) and polylactic acid (PLA) on soil properties, maize performance, and bacterial communities in soils with different salinity levels. Overall, MPs decreased soil electrical conductivity and increased NH4+-N and NO3--N contents. Adding NaCl alone had promoting and inhibitive effects on plant growth in a concentration-dependent manner. Overall, the addition of 0.2% PLA increased shoot biomass, while 2% PLA decreased it. Salinity increased Na content and decreased K/Na ratio in plant tissues (particularly roots), which were further modified by MPs. NaCl and MPs singly and jointly regulated the expression of functional genes related to salt tolerance in leaves, including ZMSOS1, ZMHKT1, and ZMHAK1. Exposure to NaCl alone had a slight effect on soil bacterial α-diversity, but in most cases, MPs increased ACE, Chao1, and Shannon indexes. Both MPs and NaCl altered bacterial community composition, although the specific effects varied depending on the type and concentration of MPs and the salinity level. Overall, PLA had more pronounced effects on soil-plant systems compared to PE. These findings bridge knowledge gaps in the risks of MPs in salt-affected habitats.
Subject(s)
Bacteria , Microplastics , Soil Microbiology , Soil Pollutants , Soil , Zea mays , Soil Pollutants/toxicity , Soil/chemistry , Microplastics/toxicity , Zea mays/drug effects , Zea mays/growth & development , Bacteria/genetics , Bacteria/drug effects , Bacteria/metabolism , Bacteria/classification , Sodium Chloride/toxicity , Polyesters , Salinity , Polyethylene , Microbiota/drug effectsABSTRACT
Because of its extreme toxicity and health risks, hexavalent chromium [Cr(VI)] has been identified as a major environmental contaminant. Bioreduction is considered as one of effective techniques for cleaning up Cr(VI)-contaminated sites, but the remediation efficiency needs to be enhanced. Here, a novel immobilized microbial agent was produced by immobilizing Bacillus cereus ZY-2009 with sodium alginate (SA) using polyvinyl alcohol (PVA) and activated carbon (AC). To evaluate the decrease of Cr(VI) by immobilized bacterial agents, batch tests were conducted with varying immobilization conditions, immobilization carriers, and dosages of medication. The removal of Cr(VI) by the agent prepared by the composite immobilization method was better than that by the adsorption and encapsulation methods. The optimal preparation conditions were the fraction of magnetic PVA was 5.00%, the fraction of SA was 4.00%, the fraction of CaCl2 was 4.00%, and the calcification time was 12â h. The experimental results indicated that PVA/SA/AC agents accelerated the reduction rate of Cr(VI). The removal rate of Cr(VI) by immobilized cells (90.5%) under ideal conditions was substantially higher than that of free cells (11.0%). This novel agent had a large specific surface area and a rich pore structure, accounting for its high reduction rate. The results suggest that the PVA/SA/AC immobilized Bacillus cereus ZY-2009 agent has great potential to remove Cr(VI) from wastewater treatment systems.
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BACKGROUND: Ameloblastoma (AM) is the most common benign odontogenic tumor, which is more often detected in the mandible than maxilla, especially the mandibular body and mandibular angle. Pediatric AM is a rare disease, especially in patients aged 10 and younger. Compared with the mainstream osteotomy and reconstructive surgery for adult ameloblastoma, there is more room for discussion in the treatment of pediatric ameloblastoma. The postoperative functional and psychological influence can not be ignored. Especially for children in the period of growth and development, an osteotomy is often challenging to be accepted by their parents. We report two patients with ameloblastoma under 10 years old who are treated with curettage and fenestration, which is a beneficial method for children with ameloblastoma. CASE PRESENTATION: We present two cases of classic ameloblastoma in children. We describe in detail the patients' characteristics, treatment processes, and follow-up result. The bone formation and reconstruction in the lesion area after fenestration decompression and curettage are recorded at every clinic review. The surgical details and principles of curettage and decompression are also described and discussed. The two patients have good bone shape recovery and no recurrence. CONCLUSIONS: Children are in the growth and development period and possess an extremely strong ability of bone formation and reconstruction. Based on the principles of minimally invasive and functional preservation, we believe that curettage combined with decompression can be the first choice for treating AM in children, especially for mandibular lesions.
Subject(s)
Ameloblastoma , Mandibular Neoplasms , Child , Humans , Ameloblastoma/surgery , Curettage/methods , Decompression , Mandible/surgery , Mandibular Neoplasms/surgeryABSTRACT
Both microplastics (MPs) and heavy metals are common soil pollutants and can interact to generate combined toxicity to soil ecosystems, but their impact on soil microbial communities (e.g., archaea and viruses) remains poorly studied. Here, metagenomic analysis was used to explore the response of soil microbiome in an agricultural soil exposed to MPs [i.e., polyethylene (PE), polystyrene (PS), and polylactic acid (PLA)] and/or Cd. Results showed that MPs had more profound effects on microbial community composition, diversity, and gene abundances when compared to Cd or their combination. Metagenomic analysis indicated that the gene taxonomic diversity and functional diversity of microbial communities varied with MPs type and dose. MPs affected the relative abundance of major microbial phyla and genera, while their coexistence with Cd influenced dominant fungi and viruses. Nitrogen-transforming and pathogenic genera, which were more sensitive to MPs variations, could serve as the indicative taxa for MPs contamination. High-dose PLA treatments (10%, w/w) not only elevated nitrogen metabolism and pathogenic genes, but also enriched copiotrophic microbes from the Proteobacteria phylum. Overall, MPs and Cd showed minimal interactions on soil microbial communities. This study highlights the microbial shifts due to co-occurring MPs and Cd, providing evidence for understanding their environmental risks.
Subject(s)
Cadmium , Metagenomics , Microplastics , Soil Microbiology , Soil Pollutants , Cadmium/toxicity , Cadmium/analysis , Soil Pollutants/toxicity , Soil Pollutants/analysis , Microplastics/toxicity , Agriculture , Microbiota/drug effects , Soil/chemistry , Bacteria/genetics , Bacteria/classification , Bacteria/drug effectsABSTRACT
Accurate prediction of the dissolved oxygen level (DOL) is important for enhancing environmental conditions and facilitating water resource management. However, the irregularity and volatility inherent in DOL pose significant challenges to achieving precise forecasts. A single model usually suffers from low prediction accuracy, narrow application range, and difficult data acquisition. This study proposes a new weighted model that avoids these problems, which could increase the prediction accuracy of the DOL. The weighting constructs of the proposed model (PWM) included eight neural networks and one statistical method and utilized Young's double-slit experimental optimizer as an intelligent weighting tool. To evaluate the effectiveness of PWM, simulations were conducted using real-world data acquired from the Tualatin River Basin in Oregon, United States. Empirical findings unequivocally demonstrated that PWM outperforms both the statistical model and the individual machine learning models, and has the lowest mean absolute percentage error among all the weighted models. Based on two real datasets, the PWM can averagely obtain the mean absolute percentage errors of 1.0216%, 1.4630%, and 1.7087% for one-, two-, and three-step predictions, respectively. This study shows that the PWM can effectively integrate the distinctive merits of deep learning methods, neural networks, and statistical models, thereby increasing forecasting accuracy and providing indispensable technical support for the sustainable development of regional water environments.
Subject(s)
Models, Theoretical , Oxygen , Models, Statistical , Neural Networks, Computer , RiversABSTRACT
Microplastics (MPs) occur and distribute widely in agroecosystems, posing a potential threat to soil-plant systems. However, little is known about their effects on legumes and N-fixing microbes. Here, we explored the effects of high-density polyethylene (HDPE), polystyrene (PS), and polylactic acid (PLA) on the growth of peanuts and soil N-fixing bacterial communities. All MPs treatments showed no phytotoxic effects on plant biomass, and PS and PLA even increased plant height, especially at the high dose. All MPs changed soil NO3--N and NH4+-N contents and the activities of urease and FDAse. Particularly, high-dose PLA decreased soil NO3--N content by 97% and increased soil urease activity by 104%. In most cases, MPs negatively affected plant N content, and high-dose PLA had the most pronounced effects. All MPs especially PLA changed soil N-fixing bacterial community structure. Symbiotic N-fixer Rhizoboales were greatly enriched by high-dose PLA, accompanied by the emergence of root nodulation, which may represent an adaptive strategy for peanuts to overcome N deficiency caused by PLA MPs pollution. Our findings indicate that MPs can change peanut-N fixing bacteria systems in a type- and dose-dependent manner, and biodegradable MPs may have more profound consequences for N biogeochemical cycling than traditional MPs.
Subject(s)
Arachis , Fabaceae , Microplastics/toxicity , Plastics , Nitrogen Fixation , Urease , Bacteria , Polyesters , Polystyrenes , SoilABSTRACT
Both nitrogen deposition (ND) and microplastics (MPs) pose global change challenges. The effects of MPs co-existing with ND on ecosystem functions are still largely unknown. Herein, we conducted a 10-month soil incubation experiment to explore the effects of polyethylene (PE) and polylactic acid (PLA) MPs on soil multifunctionality under different ND scenarios. We found that the interactions between ND and MPs affected soil multifucntionality. FAPROTAX function prediction indicated that both ND and MPs affected C and N cycling. ND increased some C-cycling processes, such as cellulolysis, ligninolysis, and plastic degradation. MPs also showed stimulating effects on these processes, particularly in the soil with ND. ND significantly decreased the abundance of functional genes NifH, amoA, and NirK, leading to inhibited N-fixation, nitrification, and denitrification. The addition of MPs also modified N-cycling processes: 0.1% PE enriched the bacterial groups for nitrate reduction, nitrate respiration, nitrite respiration, and nitrate ammonification, and 1% PLA MPs enriched N-fixation bacteria at all ND levels. We found that ND caused lower soil pH but higher soil N, decreased bacterial diversity and richness, and changed the composition and activity of functional bacteria, which explains why ND changed soil functions and regulated the impact of MPs.
Subject(s)
Microplastics , Soil , Soil/chemistry , Ecosystem , Plastics , Nitrogen/metabolism , Nitrates , Soil Microbiology , Bacteria/metabolism , PolyestersABSTRACT
OBJECTIVE: To compare the clinical efficacy between staged acupuncture based on "thoroughfare vessel is the sea of blood" theory combined with routine hormone replacement cycle treatment and routine hormone replacement cycle treatment for patients with recurrent implantation failure (RIF) of thin endometrium. METHODS: A total of 72 RIF patients with thin endometrium were randomly divided into an observation group and a control group, 36 cases in each group. The patients in the control group were treated with routine hormone replacement cycle treatment. Based on the treatment of the control group, the patients in the observation group were treated with staged acupuncture based on "thoroughfare vessel is the sea of blood" theory. The main acupoints were Neiguan (PC 6) and Gongsun (SP 4), and the supplementary acupoints were selected according to the menstrual cycle and syndrome differentiation; the acupuncture was given once every other day, 3 times a week, for 3 consecutive menstrual cycles. The thickness and shape of endometrium, and Hamilton anxiety scale (HAMA) score were observed at implantation window before and after treatment; the clinical pregnancy rate, live birth rate and cycle cancellation rate were compared between the two groups; the correlation between endometrial thickness and HAMA score was analyzed. RESULTS: Compared before treatment, the endometrial thickness in the two groups and the proportion of type A+B endometrium in the observation group were increased (P<0.05), and the HAMA scores in the two groups were decreased (P<0.05) after treatment. The above indexes in the observation group were superior to those in the control group (P<0.05). The clinical pregnancy rate and live birth rate in the observation group were higher than those in the control group (P<0.05), and the cycle cancellation rate was lower than that in the control group (P<0.05). There was a negative correlation between endometrial thickness and HAMA score (P<0.05). CONCLUSION: Based on the routine hormone replacement cycle treatment, the addition use of staged acupuncture based on "thoroughfare vessel is the sea of blood" theory could improve the thickness and shape of endometrium, relieve anxiety, increase the clinical pregnancy rate and live birth rate, and reduce the cycle cancellation rate in RIF patients with thin endometrium. The curative effect is superior to the routine hormone replacement cycle treatment alone.
Subject(s)
Acupuncture Therapy , Anxiety , Female , Pregnancy , Humans , Anxiety Disorders , Endometrium , HormonesABSTRACT
Soil remediation agents (SRAs) such as biochar and hydroxyapatite (HAP) have shown a promising prospect in in situ soil remediation programs and safe crop production. However, the effects of SRAs on soil microbial communities still remain unclear, particularly under field conditions. Here, a field case study was conducted to compare the effects of biochar and HAP on soil bacterial communities in a slightly Cd-contaminated farmland grown with sweet sorghum of different planting densities. We found that both biochar and HAP decreased the diversity and richness of soil bacteria, but they differently altered bacterial community structure. Biochar decreased Chao1 (-7.3%), Observed_species (-8.6%), and Shannon indexes (-1.3%), and HAP caused Shannon (-2.0%) and Simpson indexes (-0.1%) to decline. The relative abundance (RA) of some specific taxa and marker species was differently changed by biochar and HAP. Overall, sweet sorghum cultivation did not significantly alter soil bacterial diversity and richness but caused changes in the RA of some taxa. Some significant correlations were observed between soil properties and bacterial abundance. In conclusion, soil remediation with biochar and HAP caused alterations in soil bacterial communities. Our findings help to understand the ecological impacts of SRAs in soil remediation programs.
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Both microplastics (MPs) and cadmium (Cd) are common contaminants in soil-rice systems, but their combined effects remain unknown. Thereby, we explored the effects of three MPs, i.e., polyethylene terephthalate (PET), polylactic acid (PLA), and polyester (PES), on Cd accumulation in rice and the community diversity and structure of arbuscular mycorrhizal fungi (AMF) in soil spiked with or without Cd. Results showed that 2% PLA decreased shoot biomass (-28%), but PET had a weaker inhibitive effect. Overall, Cd alone did not significantly change shoot and root biomass and increased root biomass in combination with 0.2% PES. MPs generally increased soil Cd availability but decreased Cd accumulation in rice tissues. Both MPs and Cd improved the bioavailability and uptake of Fe and Mn in rice roots. MPs altered the diversity and community composition of AMF, depending on their type and dose and co-existing Cd. Overall, 2% PLA caused the most distinct changes in soil properties, plant growth and Cd accumulation, and AMF communities, but showed no synergistic interactions with Cd. In conclusion, MPs can mediate rice performance and Cd accumulation via altering soil properties, nutrient uptake, and root mycorrhizal communities, and biodegradable PLA MPs thought environment-friendly can exhibit higher phytotoxicity than conventional MPs.
Subject(s)
Mycobiome , Mycorrhizae , Oryza , Soil Pollutants , Cadmium/analysis , Microplastics , Plastics/analysis , Soil Pollutants/analysis , Polyethylene Terephthalates/analysis , Polyethylene Terephthalates/pharmacology , Plant Roots/chemistry , Soil/chemistry , Biodegradation, EnvironmentalABSTRACT
Bioreduction of Cr(VI) to Cr(III) by reducing microbes has attracted increasing concern. Here, Cr(VI) removal capacity of a Cr(VI)-resistant bacterium isolated from activated sludge was investigated. Based on its physio-biochemical attributes and 16S rDNA sequence analysis, the strain was identified as Bacillus cereus ZY-2009. It grew normally in the media containing 10-100â mg/L Cr(VI), indicating its high resistance to Cr(VI). Under the optimal conditions of pH 7.0, inoculation amount 10%, and temperature 30°C, Cr(VI) was effectively removed, with a removal rate of â¼80%. Co-existing Fe3+ and Cu2+ greatly increased Cr(VI) removal, but Cd2+ showed significant inhibition. Cr(VI) was removed mainly via enzyme-mediated bioreduction but not biosorption. Cr(VI) was reduced by different cell fractions (i.e. extracellular secretions, cytoplasm, and cell envelope), implying that Cr(VI) can be reduced both extracellularly and intracellularly. This strain can be used in the bioremediation of Cr(VI)-containing wastewater, with Fe3+ and Cu2+ as stimulators.
Subject(s)
Bacillus cereus , Chromium , Biodegradation, Environmental , Sewage/microbiology , Oxidation-ReductionABSTRACT
Background: Acupuncture, a treatment derived from traditional Chinese medicine, can effectively relieve the symptoms and improve pregnancy outcome in patients with polycystic ovary syndrome (PCOS); however, its mechanism remains unclear. This study aimed at investigating whether acupuncture could improve endometrial angiogenesis and thus endometrial receptivity via activating PI3K/AKT pathway in PCOS rats. Methods: We established a rat model with PCOS, which was induced by DHEA. Acupuncture was performed every other day for 15 days, and the PI3K inhibitor (LY294002) was intraperitoneal injected 30 mins before acupuncture treatment. Females rats were mated with male SPF SD rats in a ratio of 2 : 1 after treatment and sacrificed on the 5th day when the vaginal plug was identified. The number of implantation sites was observed, followed by ovarian and endometrial morphology detected with hematoxylin-eosin staining and a scanning electron microscope, estrous cycle detected with vaginal smear analysis, and sex hormones and angiogenesis-related PI3K/AKT gene/protein expression detected with enzyme-linked immunosorbent assay, western blotting, immune histochemistry, and quantitative real-time PCR. Results: Acupuncture notably improved implantation sites' number, endometrial receptivity factors including endometrial morphology, pinopodes, HOX-10, and LIF protein expression, as well as angiogenesis and PI3K/AKT pathway factors such as VEGF, VEGFR2, Ang-1, PI3K, AKT, and P-AKT gene/protein expression and the level of eNOS and NO in the endometrium of rats with PCOS; PCOS-like symptoms were alleviated as well. The efficacy of acupuncture on a rat model with PCOS was counteracted by the combination with the PI3K inhibitor. Conclusion: Acupuncture improves endometrial angiogenesis by activating the PI3K/AKT pathway, thus promoting endometrial receptivity and the number of implantation sites in rats with PCOS.
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A 100-day soil incubation experiment was conducted to explore the effects of conventional (high-density polyethylene, HDPE) and biodegradable (polylactic acid, PLA) microplastics (MPs) and multiwall carbon nanotubes (MWCNTs) on soil geochemical properties and bacterial communities. Generally, soil pH was increased by 10% HDPE and 10% PLA, but decreased by increasing MWCNTs. Soil dissolved organic carbon content was only increased by 10% PLA. NO3--N content was significantly decreased by MPs, with a decrement of 99% by 10% PLA. Similarly, available P content was reduced by 10% MPs. The activities of urease and alkaline phosphatase were stimulated by 10% PLA, but generally inhibited by HDPE. Conversely, FDAse activity was stimulated by HDPE, but inhibited by 10% PLA, whereas invertase activity decreased with increasing MWCNTs. Overall, both MPs and MWCNTs changed soil bacterial diversity. Co-exposure to 10% MPs and MWCNTs of 1 and 10 mg/kg caused the lowest species richness and Shannon indexes. MPs especially at the 10% dose changed bacterial community composition and the associated metabolic pathways, causing the enrichment of specific taxa and functional genes. Our findings show that conventional and biodegradable MPs differently change soil geochemical properties and microbial community structure and functions, which can be further modified by co-existing MWCNTs.
Subject(s)
Nanotubes, Carbon , Soil , Bacteria/genetics , Microplastics , Nanotubes, Carbon/toxicity , Plastics , Polyesters , Polyethylene , Soil/chemistry , Soil MicrobiologyABSTRACT
Microplastics (MPs) co-occur widely with diverse contaminants in soils. However, few data are available on their impacts on soil chemical and microbial properties of heavy metal-contaminated soils. For the first time, we investigated the changes in chemical and microbial properties of a Pb-Zn-contaminated soil as induced by six different MPs, including polyethylene (PE), polystyrene (PS), polyamide (PA), polylactic acid (PLA), polybutylene succinate (PBS), and polyhydroxybutyrate (PHB), at two doses (0.2% and 2%, w/w). After 120 days of soil incubation, significant changes were observed in soil pH, dissolved organic carbon (DOC), NH4+-N, NO3--N, available P, the availability of Zn and Pb, and the activities of soil enzymes. Overall, MPs especially at the dose of 2% decreased the richness and diversity of bacterial communities and altered microbial community composition, causing special enrichments of specific taxa. MPs increased predicted functional genes involved in xenobiotics biodegradation and metabolism. Generally, impacts were dependent on MPs' type and dose. Changes in soil properties and heavy metal availability had significant correlations with bacterial community diversity and composition. Our findings imply that MPs co-occurring with heavy metals may change metal mobility, soil fertility, and microbial diversity and functions, thus causing a potential threat to soil ecosystem multifunctionality.
Subject(s)
Metals, Heavy , Microbiota , Soil Pollutants , Dissolved Organic Matter , Metals, Heavy/toxicity , Microplastics , Plastics , Soil , Soil Microbiology , Soil Pollutants/analysis , Zinc/toxicityABSTRACT
Microplastics (MPs) are a type of emerging contaminants that pose a potential threat to global terrestrial ecosystems, including agroecosystems. In recent years, MPs in soil and their adverse effects on soil health and fertility have attracted increasing concern. Based on the current knowledge, this review begins with a summary of the occurrence and characteristics of MPs in various soil environments, and then highlights the impacts of MPs on soil physical, chemical, and microbiological properties. Data show that MPs occur widely in all surveyed soil types, such as agricultural soils, industrial soils, urban soils, and unused soils, but show variation in their abundance, type, shape, and size. In most cases, MPs can change soil physical, chemical, and microbiological properties, but the effects vary, and are dependent on polymer type, shape, dose, and size. MPs-induced changes in soil fertility and the availability of pollutants may pose a potential threat to plant performance and crop productivity and safety. Particularly, MPs influence the emission of greenhouse gases from soil, ultimately leading to uncertain consequences for global climate change. More comprehensive and in-depth studies are required to fill large knowledge gaps.
Subject(s)
Microplastics , Soil , Agriculture , Ecosystem , Plastics/toxicityABSTRACT
Microplastics (MPs) are emerging contaminants in terrestrial systems that cause diverse impacts on plants. However, little is known about whether MPs especially micro-sized MPs can be accumulated and translocated in plants particularly food crops. Hereby, a hydroponic experiment was conducted to verify whether nano-sized (80 nm) and micro-sized (1 µm) fluorescently labeled polystyrene (PS) microspheres can enter rice roots and translocate to aerial parts. Plant samples were taken for detection of PS after 14 days and 40 days exposure, respectively. Both nano- and micro-sized PS microspheres were detected in roots, stems, and leaves of rice seedlings by using confocal laser scanning microscopy. Both 80 nm and 1 µm PS microspheres accumulated in the vascular systems of plant tissues, especially root stele, stem vascular bundles and leaf veins, and mostly aggregated on cell walls and in the intercellular regions. These findings imply that both nano- and micro-sized MPs could be absorbed by rice roots and subsequently translocated to aerial parts, and apoplastic transport may be the main pathway. In conclusion, rice seedlings can accumulate nano/microplastics in their roots and translocate them to aboveground tissues, thereby possibly transferring the accumulated nano/microplastics to higher trophic levels through the food chain.
Subject(s)
Microplastics , Oryza , Hydroponics , Plastics , Polystyrenes , SeedlingsABSTRACT
Soil pollution with heavy metals has attracted increasing concern, which calls for the development of new remediation strategies. The combination of physical, chemical, and biological techniques can achieve more efficient remediation. However, few studies have focused on whether nanomaterials and beneficial microbes can be jointly used to facilitate phytoremediation. Therefore, we studied the role of nano-zero-valent iron (nZVI) and arbuscular mycorrhizal (AM) fungi in the phytoremediation of an acidic soil polluted with Cd, Pb and Zn, using sweet sorghum. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and mapping analyses were conducted to explore the mechanisms of metal immobilization by nZVI. The results showed that although both bare nZVI (B-nZVI) and starch-stabilized nZVI (S-nZVI) inhibited root mycorrhizal colonization, Acaulospora mellea ZZ successfully colonized the plant roots. AM inoculation significantly reduced the concentrations of DTPA-Cd, -Pb, and -Zn in soil, and the concentrations of Cd, Pb, and Zn in plants, indicating that AM fungi substantially facilitated heavy metal immobilization. Both B-nZVI and S-nZVI, ranging from 50 mg/kg to 1000 mg/kg, did not impede plant growth, and generally enhanced the phytoextraction of heavy metals. XRD, EDS and mapping analyses showed that S-nZVI was more susceptible to oxidation than B-nZVI, and thus had more effective immobilization effects on heavy metals. Low concentrations of nZVI (e.g., 100 mg/kg) and AM inoculation had synergistic effects on heavy metal immobilization, reducing the concentrations of Pb and Cd in roots and enhancing root Zn accumulation. In conclusion, our results showed that AM inoculation was effective in immobilizing heavy metals, whereas nZVI had a low phytotoxicity, and they could jointly contribute to the phytoremediation of heavy metal-contaminated soils with sweet sorghum.
ABSTRACT
Herein, an environmentally friendly biomimetic strategy was proposed and validated for the catalytic hydrogenation reaction in live bacteria. First, we used a thermophilic hydrogen-producing bacterial strain to in situ prepare ultrafine gold nanoparticles (AuNPs) and palladium nanoparticles (PdNPs). Then, by utilizing AuNPs or PdNPs as catalysts and on-site hydrogen gas generated directly through living thermophilic hydrogen-producing bacteria, we realized highly efficient asymmetric hydrogenation reactions.