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1.
J Environ Sci (China) ; 103: 80-92, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33743921

RESUMEN

In this study, transport behaviors of graphene oxide (GO) in saturated uncoated (i.e., clean sand) and goethite-coated sand porous media were examined as a function of the phosphate. We found that phosphate enhanced the transport of GO over a wide range of solution chemistry (i.e., pH 5.0-9.0 and the presence of 10 mmol/L Na+ or 0.5 mmol/L Ca2+). The results were mainly ascribed to the increase of electrostatic repulsion between nanoparticles and porous media. Meanwhile, deposition site competition induced by the retained phosphate was another important mechanism leading to promote GO transport. Interestingly, when the phosphate concentration increased from 0.1 to 1.0 mmol/L, the transport-enhancement effect of phosphate in goethite-coated sand was to a much larger extent than that in clean sand. The observations were primarily related to the difference in the total mass of retained phosphate between the iron oxide-coated sand and clean sand columns, which resulted in different degrees of the electrostatic repulsion and competitive effect of phosphate. When the background solution contained 0.5 mmol/L Ca2+, phosphate could be bind to sand/ goethite-coated sand surface by cation bridging; and consequently, promoted competition between phosphate and nanoparticles for deposition sites, which was an important mechanism for the enhanced effect of phosphate. Moreover, the DLVO theory was applicable to describe GO transport behaviors in porous media in the absence or presence of phosphate. Taken together, these findings highlight the important status and role of phosphate on the transport and fate of colloidal graphene oxide in the subsurface environment.


Asunto(s)
Nanopartículas , Dióxido de Silicio , Compuestos Férricos , Grafito , Fosfatos , Porosidad , Arena
2.
Dig Endosc ; 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33527576

RESUMEN

OBJECTIVE: The topical antispasmodic agent l-menthol is commonly used for gastric peristalsis suppression during diagnostic upper gastrointestinal (GI) endoscopy. We evaluated the efficacy and safety of a single dose l-menthol solution in suppressing gastric peristalsis during upper GI endoscopy in Chinese patients. METHODS: In this phase III, multicenter, randomized, double-blind, placebo-controlled study (ClinicalTrials.gov: NCT03263910), 220 patients scheduled to undergo upper GI endoscopy at five Chinese referral centers received a single dose of either 160 mg of l-menthol (n = 109) or placebo (n = 111). Both treatments were sprayed endoscopically on the gastric mucosa. An independent committee evaluated the degree of gastric peristalsis (peristaltic score: grade 1-5). RESULTS: At baseline, the proportion of patients with grade 1 peristalsis (no peristalsis) did not differ between the groups. The proportion of patients with grade 1 peristalsis post-treatment was significantly higher in the l-menthol group (40.37%, 44/109) versus the placebo group (16.22%, 18/111; P < 0.001); the difference between the groups was 24.15% (95% confidence interval: 12.67%-35.63%; P < 0.001). In the l-menthol group, 61.47% of patients had grade 1 peristalsis after endoscopy versus 24.55% in the placebo group (P < 0.001). The ease of intragastric examination correlated significantly with the grade of peristalsis. The incidence of adverse events was comparable between the groups (P = 0.340). CONCLUSIONS: During upper GI endoscopy, a single dose of l-menthol solution (160 mg) sprayed on the gastric mucosa significantly attenuated gastric peristalsis versus placebo, thereby improving the visual stability without any safety concerns.

3.
Interdiscip Sci ; 2021 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-33641077

RESUMEN

Computed tomography (CT) is one of the most efficient diagnostic methods for rapid diagnosis of the widespread COVID-19. However, reading CT films brings a lot of concentration and time for doctors. Therefore, it is necessary to develop an automatic CT image diagnosis system to assist doctors in diagnosis. Previous studies devoted to COVID-19 in the past months focused mostly on discriminating COVID-19 infected patients from healthy persons and/or bacterial pneumonia patients, and have ignored typical viral pneumonia since it is hard to collect samples for viral pneumonia that is less frequent in adults. In addition, it is much more challenging to discriminate COVID-19 from typical viral pneumonia as COVID-19 is also a kind of virus. In this study, we have collected CT images of 262, 100, 219, and 78 persons for COVID-19, bacterial pneumonia, typical viral pneumonia, and healthy controls, respectively. To the best of our knowledge, this was the first study of quaternary classification to include also typical viral pneumonia. To effectively capture the subtle differences in CT images, we have constructed a new model by combining the ResNet50 backbone with SE blocks that was recently developed for fine image analysis. Our model was shown to outperform commonly used baseline models, achieving an overall accuracy of 0.94 with AUC of 0.96, recall of 0.94, precision of 0.95, and F1-score of 0.94. The model is available in https://github.com/Zhengfudan/COVID-19-Diagnosis-and-Pneumonia-Classification .

4.
BMC Gastroenterol ; 21(1): 84, 2021 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-33622256

RESUMEN

BACKGROUND: Hepatic cavernous hemangioma is the most common type of benign liver tumor. Although ruptures and hemorrhages of hepatic hemangioma are rare complications, they are associated with high mortality. Most practitioners only pay more attention to abdominal hemorrhages caused by the rupture of hepatic hemangiomas. However, spontaneous intracapsular hemorrhages can often be neglected and poorly understood. CASE PRESENTATION: A 65-year-old man was referred to our institution with right upper quadrant pain, which had occurred suddenly and without a history of recent trauma. The blood test results were normal. Magnetic resonance imaging (MRI) of the abdomen showed a cystic mass in the right liver lobe. Considering the possibility of hepatic cystadenoma with hemorrhage, the patient underwent a right hepatic lobectomy. The pathological findings unexpectedly revealed intratumoral hemorrhage of hepatic hemangioma. The patient recovered well and was discharged eight days after surgery. CONCLUSIONS: Intracapsular hemorrhage of hepatic cavernous hemangioma is challenging to diagnose and has a high potential risk of rupture. MRI is beneficial for diagnosing subacute internal hemorrhage cases, and it is recommended to undergo surgery for patients with a definitive diagnosis.

6.
Surg Endosc ; 2021 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-33538902

RESUMEN

BACKGROUND: Endoscopic submucosal dissection (ESD) is a prominent minimally invasive operative technique for treating early gastrointestinal tumors but can result in postoperative bleeding. We conducted a randomized controlled trial to determine whether increasing blood pressure under hemostasis during gastric ESD to identify potential bleeding spots reduces the risk of post-ESD bleeding. METHODS: In this randomized, controlled, single-blinded clinical trial, 309 patients with early gastric cancer who were admitted to a hospital to undergo ESD were recruited from March 2017 to February 2018 and were randomized into intervention and control groups. In the control group, patients underwent normal ESD. In the intervention group, we increased patients' blood pressure to 150 mmHg for 5 min using a norepinephrine pump (0.05 µg/kg/min initial dose) after the specimen was extracted during the ESD operation to identify and coagulate potential bleeding spots with hot biopsy forceps. Our primary outcome was the incidence of postoperative bleeding over 60-day follow-up. RESULTS: The incidence of post-ESD bleeding was lower in the intervention group (1.3%, 2/151) than in the control group (10.1%, 16/158, p = 0.01). Deeper tumor invasion was associated with a higher risk of post-ESD bleeding (5.3% in mucosal/submucosal layer 1 group vs. 12.5% in submucosal layer 2/muscularis propria group, p < 0.001). Multi-factor but not univariate analysis showed that proton pump inhibitor administration three times per day may be a better choice than twice per day. CONCLUSION: Increasing blood pressure under hemostasis during ESD to identify and coagulate potential bleeding spots could reduce the risk of delayed bleeding after gastric ESD.

7.
Sci Rep ; 11(1): 2911, 2021 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-33536447

RESUMEN

The soil carbon (C) pools in coastal wetlands are known as "blue C" and have been damaged extensively owing to climate change and land reclamation. Because soil respiration (RS) is the primary mechanism through which soil carbon is released into the atmosphere at a global scale, investigating the dynamic characteristics of the soil respiration rate in reclaimed coastal wetlands is necessary to understand its important role in maintaining the global C cycle. In the present study, seasonal and diurnal changes in soil respiration were monitored in one bare wetland (CK) and two reclaimed wetlands (CT, a cotton monoculture pattern, and WM, a wheat-maize continuous cropping pattern) in the Yellow River Delta. At the diurnal scale, the RS at the three study sites displayed single-peak curves, with the lowest values occurring at midnight (00:00 a.m.) and the highest values occurring at midday (12:00 a.m.). At the seasonal scale, the mean diurnal RS of the CK, CT and WM in April was 0.24, 0.26 and 0.79 µmol CO2 m-2 s-1, and it increased to a peak in August for these areas. Bare wetland conversion to croplands significantly elevated the soil organic carbon (SOC) pool. The magnitude of the RS was significantly different at the three sites, and the yearly total amounts of CO2 efflux were 375, 513 and 944 g CO2·m-2 for the CK, CT and WM, respectively. At the three study sites, the surface soil temperature had a significant and positive relationship to the RS at both the diurnal and seasonal scales, and it accounted for 20-52% of the seasonal variation in the daytime RS. The soil water content showed a significant but negative relationship to the RS on diurnal scale only at the CK site, while it significantly increased with the RS on seasonal scale at all study sites. Although the RS showed a noticeable relationship to the combination of soil temperature and water content, the synergic effects of these two environment factors were not much higher than the individual effects. In addition, the correlation analysis showed that the RS was also influenced by the soil physico-chemical properties and that the soil total nitrogen had a closer positive relationship to the RS than the other nutrients, indicating that the soil nitrogen content plays a more important role in promoting carbon loss.

8.
Nanotechnology ; 2021 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-33440356

RESUMEN

Composite electrocatalysts of carbon and metals or metal compounds with homogeneous active sites can be obtained through the carbonization of metal organic framework (MOF) materials under inert atmosphere. In this work, a three-phase composite electrocatalysts NiFe2O4/Ni@C were prepared via pyrolysis from self-assembled MOF nanosheets aggregates. The excellent electrocatalytic activity of the obtained electrocatalysts with various Ni:Fe ratios is demonstrated. Especially, the NiFe2O4/Ni@C sample with the mole ratio of Ni:Fe=1:1 can use the overpotential (ƞ) of 330 and 423 mV to drive 10 and 50 mA cm-2 respectively. After 80000s/22 h, the current density could retained 90% of the initial current density. The excellent activity and stability of the electrocatalysts are attributed to nickel and iron ions with uniform dispersion at atomic level in the NiFe2O4 phase and the synergistic effect of nickel and NiFe2O4 nanoparticles with amorphous carbon atoms or nanoparticles around.

9.
Chemosphere ; : 129081, 2020 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-33288283

RESUMEN

Since iron oxide minerals are ubiquitous in natural environments, the release of graphene oxide (GO) into environmental ecosystems can potentially interact with iron oxide particles and thus alter their surface properties, resulting in the change of their transport behaviors in subsurface systems. Column experiments were performed in this study to investigate the co-transport of GO nanoparticles and hematite colloids (a model representative of iron oxides) in saturated sand. The results demonstrated that the presence of hematite inhibited GO transport in quartz sand columns due to the formation of less negatively charged GO-hematite heteroaggregates and additional deposition sites provided by the adsorbed hematite on sand surfaces. Contrarily, GO co-present in suspensions significantly enhanced the transport of hematite colloids through different mechanisms such as the increase of electrostatic repulsion, decreased physical straining, GO-facilitated transport of hematite (i.e., highly mobile GO nanoparticles served as a mobile carrier for hematite). We also found that the co-transport behaviors of GO and hematite depended on solution chemistry (e.g., pH, ionic strength, and divalent cation (i.e., Ca2+)), which affected the electrostatic interaction as well as heteroaggregation behaviors between GO nanoparticles and hematite colloids. The findings provide an insight into the potential fate of carbon nanomaterials affected by mineral colloids existing in natural waters and soils.

10.
Artículo en Inglés | MEDLINE | ID: mdl-33382122

RESUMEN

BACKGROUND AND AIM: Traditionally, surgery is the only choice for esophageal foreign bodies (FBs) penetrating into the mediastinum or cervical para-esophageal space. Recent progress in endoscopic techniques and devices has made it possible to perform endoscopic procedures in the mediastinum. Here, we describe a novel method to remove the entirely embedded esophagus-penetrating FBs through an endoscopic approach. METHODS: Patients who underwent endoscopic removal of entirely embedded esophagus-penetrating FBs were prospectively enrolled between December 2018 and June 2020. All procedures were performed by using five major steps: localization of the FB; mucosal incision; wound debridement, myotomy, and FB exposure; FB extraction; and closure of the esophageal wound. RESULTS: A total of five cases of entirely embedded esophagus-penetrating FBs were evaluated, two in children and three in adults. All FBs were successfully removed and extracted using a therapeutic endoscope and a hook knife or a hybrid knife and a grasping forceps as accessories. The average procedure time was 19.0 ± 12.4 min (range 10-40 min). The major surgical procedure was avoided in all patients. The average length of hospital stay was 3.8 ± 2.5 days (range 2-8 days). There were no severe short-term adverse events after all procedures. During the 1 month and 3 months follow-up, no patient developed long-term adverse events including stenosis of the esophagus and fistula formation. CONCLUSIONS: Endoscopic approach was a safe and effective way to remove entirely embedded esophagus-penetrating FBs.

11.
Mol Ther Nucleic Acids ; 22: 557-571, 2020 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-33230457

RESUMEN

Nasopharyngeal carcinoma (NPC) is prevalent in East and Southeast Asia. In a previous study, Epstein-Barr virus (EBV)-miR-BART22 induces tumor metastasis and stemness and is significantly involved in NPC progression. In the present study, we observed that miR-4721 is induced by EBV-miR-BART22 through phosphatidylinositol 3-kinase (PI3K)/AKT/c-JUN/Sp1 signaling to promote its transcription. In a subsequent study, we observed that miR-4721 serves as a potential oncogenic factor promoting NPC cell cycle progression and cell proliferation in vitro and in vivo. Mechanism analysis indicated that miR-4721 directly targetes GSK3ß and reduces its expression, which therefore elevates ß-catenin intra-nuclear aggregation and activates its downstream cell cycle factors, including CCND1 and c-MYC. In clinical samples, miR-4721 and GSK3ß are respectively observed to be upregulated and downregulated in NPC progression. Elevated expression of miR-4721 is positively associated with clinical progression and poor prognosis. Our study first demonstrated that miR-4721 as an oncogene is induced by EBV-miR-BART22 via modulating PI3K/AKT/c-JUN/Sp1 signaling to target GSK3ß, which thus activates the WNT/ß-catenin-stimulated cell cycle signal and enhances the tumorigenic capacity in NPC. miR-4721 may be a potential biomarker or therapeutic target in NPC treatment in the future.

12.
Environ Pollut ; 268(Pt A): 115730, 2020 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-33007596

RESUMEN

In this study, batch and column tests were performed to investigate the co-transport of graphene oxide (GO) nanoparticles and tetracycline in saturated porous media under various solution chemistry conditions. Research indicated that GO and tetracycline had mutual promotion effect on their transport in the porous media under all the tested conditions, which was ascribed to the high adsorption capacity of tetracycline onto GO and the increased electrostatic repulsion as well as their competition for deposition sites on sand surfaces. Interestingly, the mutually promoting function of GO and tetracycline under acidic conditions was greater than that under alkaline conditions, the dominant mechanism was that the increased solution pH decreased the sorption of tetracycline onto GO and weakened the deposition site competition. Furthermore, the mutually promoting effect of GO and tetracycline was Na+ or Ca2+ concentration-dependent. Specially, increased Ca2+ concentration weakened the promoting effect of GO on tetracycline transport but magnified the promoting effect of tetracycline on GO transport. This is because higher Ca2+ concentration could cause a decrease in the adsorption of tetracycline on GO and facilitate more tetracycline molecules to occupy the deposition sites on sand surfaces. Additionally, sodium dodecyl sulfate had enhancement effect on co-transport of GO and tetracycline. Findings from this study clearly indicated that antibiotics and carbon based nanomaterials may transport together under various solution chemistry conditions, and consequently affect their fates in aquatic environments.

13.
J Environ Qual ; 49(2): 335-345, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33016435

RESUMEN

Biochar is composed of carbonaceous and inorganic (ash) fractions. The structural properties of carbonaceous fractions and the composition of ash in biochar are both variable with pyrolysis temperature. However, it is unknown whether ash may play different roles in sorption of organic compounds to the carbonaceous fraction of biochars produced at different temperatures. Hence, in this study, the pristine biochars produced at 300-900°C and their corresponding deashed biochars were investigated, and the combined roles of carbonaceous fraction and ash in sorption of triclosan were compared. The results showed that the biochars produced at 300-400°C had high content of uncarbonized organic structure with dominating partition effect. The combination of uncarbonized organic structure and ash had comparable or even higher sorption coefficient (KD ) for triclosan at low concentration compared with a single uncarbonized organic structure. However, for the biochars produced at 600-900°C, which were mainly composed of carbonized or graphitized carbon structure, ash had significant effect on triclosan sorption by reducing surface adsorption and pore filling effect. The combination of carbonaceous fraction and ash decreased KD values for triclosan at any tested concentrations. In addition, the results of pH effect on sorption indicated that ash possibly decreased the electrostatic repulsion of deprotonated phenolic hydroxyl between biochars and triclosan. Accordingly, it will be more valuable to design biochars for pollutant sorption from the perspective of combined role of carbonaceous fraction and ash rather than a single role of carbonaceous fraction.


Asunto(s)
Triclosán , Madera , Carbón Orgánico , Temperatura
14.
J Environ Qual ; 49(5): 1396-1407, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33016453

RESUMEN

The different effects of nitrogen-flow (NF) and air-limitation (AL) pyrolysis on the characteristics and nutrient retention of biochars (BCs) are unclear. Hence, in this study, BCs derived from bamboo, corn straw, and wheat straw were produced in AL and NF atmospheres at various temperatures (300-750 °C), and their different characteristics and nutrient retention rates were compared systematically. Nitrogen-flow pyrolysis facilitates C retention and graphitic C formation, and AL pyrolysis improves the polarity and supports the formation of oxygen-containing groups. With increasing pyrolysis temperature, C retention and graphitic C formation in BCs derived from AL pyrolysis decreases more significantly compared with BCs from NF pyrolysis. At 750 °C, the polarity and oxygen-containing groups of BCs derived from AL pyrolysis increase, whereas those from BCs derived from NF pyrolysis decrease. The observations are attributable to the AL and high-temperature-enhanced oxidization and gasification of C. An AL atmosphere with a higher pyrolysis temperature supports porosity and results in a larger specific surface area. Although pyrolysis temperature and atmosphere have negligible effects on nutrient retention, a low pyrolysis temperature facilitates the formation of water-soluble Ca, Mg, and P, and AL pyrolysis facilitates the formation of water-soluble P because the high pyrolysis temperature improves the pH and mineral stability of BCs, and air limitation facilitates the oxidation of organic P into PO4 3- . This study provides a reference for selecting AL or NF pyrolysis based on various pyrolysis temperatures to produce BCs and applying these in C sequestration, contaminant sorption, and soil quantity improvement.


Asunto(s)
Carbón Orgánico , Nitrógeno , Nutrientes , Temperatura
15.
Ecotoxicol Environ Saf ; 205: 111345, 2020 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-32961496

RESUMEN

With the broadly application of antibiotics to treat infectious diseases in humans and animals, antibiotic contaminants such as tetracycline (TC) and ciprofloxacin (CIP) have been detected in soil environments, where iron oxide minerals and phosphate are ubiquitous. To date, the influence of phosphate on the adsorption behaviors of TC/CIP onto iron oxides is still poorly understood. In this study, the effects of phosphate on the adsorptions of TC and CIP onto iron oxide minerals were investigated. Adsorption isotherms showed that the adsorption affinities of TC and CIP onto the three iron oxide minerals were in the order of goethite > hematite > magnetite with or without phosphate, the trend was dominated by different surface area and amount of surface hydroxyl groups of iron oxide minerals. Meanwhile, TC contains more functional groups than CIP for bonding, which resulted in greater adsorption affinity of three iron oxides to TC than that to CIP. Interestingly, phosphate weakened TC adsorption, while enhanced CIP adsorption, on the three iron oxides. This observation was ascribed to that phosphate anion enhanced the surface negative charge of iron oxides, which reinforced the electrostatic repulsion between iron oxides and negatively charged TC, also reinforced the electrostatic attraction between iron oxides and positively charged CIP. Furthermore, the inhibitory effect of phosphate on TC adsorption was dramatically enhanced at high pH, while the promoting effect of phosphate on CIP adsorption was slightly changed with various pH. Our results highlight the importance of phosphate in exploring the environmental fate of antibiotics in natural environment.


Asunto(s)
Ciprofloxacino/química , Compuestos Férricos/química , Tetraciclina/química , Adsorción , Antibacterianos , Óxido Ferrosoférrico , Concentración de Iones de Hidrógeno , Compuestos de Hierro , Minerales , Fosfatos , Suelo , Contaminantes del Suelo
16.
Artículo en Chino | MEDLINE | ID: mdl-32791648

RESUMEN

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a kind of very rare idiopathic disease. The most common feature is the excessive accumulation of Langerhans cells in lymph nodes, but it may also occur in other areas and lead to related organ damage. We report a case of a 60-year-old man with Rosai-Dorfman disease, which led to dyspnea. Surgery is the best treatment to relieve the patient's dyspnea in a short time. Rosai-Dorfman disease has trend to self-healing, but in the case of special location, surgery should be selected. Some similar mass recurred in the operative area and bilateral nasal cavity in half a year after operation. Now we reviewed the relevant literatures and summarized the experience of diagnosis and treatment in Rosai-Dorfman disease.


Asunto(s)
Histiocitosis Sinusal , Disnea , Humanos , Ganglios Linfáticos , Masculino , Persona de Mediana Edad , Cavidad Nasal , Recurrencia
17.
J Bus Res ; 2020 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-32836565

RESUMEN

This research examines the tension between the aims of the United Nations' Sustainable Development Goal 8 (SDG 8), to promote productive employment and decent work, and the adoption of Artificial Intelligence (AI). Our findings are based on the analysis of 232 survey results, where we tested the effects of AI adoption on workers' psychological contract, engagement and trust. We find that psychological contracts had a significant, positive effect on job engagement and on trust. Yet, with AI adoption, the positive effect of psychological contracts fell significantly. A further re-examination of the extant literature leads us to posit that AI adoption fosters the creation of a third type of psychological contract, which we term "Alienational". Whereas SDG 8 is premised on strengthening relational contracts between an organization and its employees, the adoption of AI has the opposite effect, detracting from the very nature of decent work.

18.
Sci Total Environ ; 742: 140416, 2020 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-32721714

RESUMEN

A crucial mechanism for the application of biochar in soil improvement is the direct release of nutrients from biochar. Low molecular weight organic acids (LMWOAs) ubiquitously exist in soil. However, the mechanism of LMWOAs-mediated release of nutrients from biochars remains little known. Ten biochars with different mineral element stoichiometric ratio were produced, and four LMWOAs [acetic (HAc), glycolic (GA), tartaric (TA), and citric acids (CA)] were employed, to enunciate the influence mechanism of LMWOAs on the release of phosphorus and potassium from biochar. The results showed that HAc suppressed the release of P from biochars, while TA and CA facilitated the release of P from biochars with high ratios of polyvalent metals to P. A new mechanism was proposed that the deprotonated HAc combined with the dissolved HPO42- or H2PO4- to form a complex through hydrogen bond and cation bridging. The hydrophobic methyl group of HAc was exposed outside of the complex, which decreased the water-solubility of phosphate. Meanwhile, a high ratio of polyvalent metals to P benefited more P to combine with polyvalent metals, which decreased the water-solubility of P, but the deprotonated TA and CA are polyvalent anions that could substitute this part of P by anion exchange. Also, LMWOAs promoted the release of K from biochars with low K/(P + S) ratios, possibly due to unionized carboxyl of LMWOAs served as a hydrogen bond donor to displace K out of biochars. This study gives a deep understanding of the fate of biochar originated nutrients response to LMWOAs.


Asunto(s)
Fósforo , Contaminantes del Suelo/análisis , Carbón Orgánico , Minerales , Peso Molecular , Potasio , Suelo
19.
Huan Jing Ke Xue ; 41(4): 1847-1854, 2020 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-32608693

RESUMEN

The contents and sources of 15 US EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in 59 surface soil samples (0-10 cm depth) collected from six functional zones, including cultural and educational area, park, residential area, vegetable garden, gas station, and industrial area, in Yangzhou City. The toxicity equivalent content of benzo[a]pyrene (TEQBaP) was adopted to assess PAH risks in soils. The results showed that the contents of Σ15PAHs in soil samples ranged from 21 to 36118 µg·kg-1, with a median value of 295 µg·kg-1. The composition of PAHs was dominated by 4-6 ring PAHs. The average contents of Σ15PAHs in various functional zones in Yangzhou City was in the order of industrial area > gas station > cultural and educational area > vegetable garden > residential area > park. Correlation analysis showed that the contents of Σ15PAHs were significantly positively correlated with the contents of both TOC (P<0.05) and BC (P<0.01) in soil samples from whole Yangzhou City. However, the contents of Σ15PAHs had no significant correlations with the contents of both TOC and BC in soil samples within each functional zone except gas station, in which the contents of Σ15PAHs had a significant correlation with those of BC (P<0.01). The results of PAH ratios showed that the sources of PAHs in soils of various functional zones were mainly from oil leakage and the combustion of oil, coal, and biomass, although there were some differences among them. The values of ΣTEQBaP of 15 PAHs ranged from 2 to 4448 µg·kg-1 in the soil samples of Yangzhou City. According to the standard value of 33 µg·kg-1 of ΣTEQBaP for 10 PAHs in the soil environmental standard of Netherland, 45.8% of soil samples exceeded the standard in Yangzhou City. The percentages of soil samples exceeding the standard of various functional zones in Yangzhou City were in the order of industrial area (70%) > gas station (60%) > cultural and educational area (55.6%) > vegetable garden (50.0%) > residential area (30%) > park (10%). Hence, in all the functional zones of Yangzhou City, there were some soil samples with potential ecological risks, which was relatively higher in industrial area and gas station, and relatively lower in residential area and park.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes del Suelo/análisis , China , Ciudades , Monitoreo del Ambiente , Medición de Riesgo , Suelo
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