Hypoxia-inducible factor prolyl hydroxylase inhibitor alleviates heatstroke-induced acute kidney injury by activating BNIP3-mediated mitophagy.

Hypoxia-induced inflammation and apoptosis are important pathophysiological features of heat stroke-induced acute kidney injury (HS-AKI). Hypoxia-inducible factor (HIF) is a key protein that regulates cell adaptation to hypoxia. HIF-prolyl hydroxylase inhibitor (HIF-PHI) stabilizes HIF to increase cell adaptation to hypoxia. Herein, we reported that HIF-PHI pretreatment significantly improved renal function, enhanced thermotolerance, and increased the survival rate of mice in the context of HS. Moreover, HIF-PHI could alleviate HS-induced mitochondrial damage, inflammation, and apoptosis in renal tubular epithelial cells (RTECs) by enhancing mitophagy in vitro and in vivo. By contrast, mitophagy inhibitors Mdivi-1, 3-MA, and Baf-A1 reversed the renoprotective effects of HIF-PHI. Mechanistically, HIF-PHI protects RTECs from inflammation and apoptosis by enhancing Bcl-2 adenovirus E18 19-kDa-interacting protein 3 (BNIP3)-mediated mitophagy, while genetic ablation of BNIP3 attenuated HIF-PHI-induced mitophagy and abolished HIF-PHI-mediated renal protection. Thus, our results indicated that HIF-PHI protects renal function by upregulating BNIP3-mediated mitophagy to improve HS-induced inflammation and apoptosis of RTECs, suggesting HIF-PHI as a promising therapeutic agent to treat HS-AKI.

A New Method Used to Enhance the SPAIR Image of the Spine MRI.

BACKGROUND: Magnetic resonance imaging (MRI) is a handy diagnostic tool for orthopedic disorders, particularly spinal and joint diseases. METHODS: The lumbar intervertebral disc is visible in the T1 and T2 weight sequences of the spine MRI, which aids in diagnosing lumbar disc herniation, lumbar spine tuberculosis, lumbar spine tumors, and other conditions. The lumbar intervertebral disc cannot be seen accurately in the Spectral Attenuated Inversion Recovery (SPAIR) due to weaknesses in the fat and frequency offset parameters, which is not conducive to developing the intelligence diagnosis model of medical image. RESULTS: In order to solve this problem, we propose a composite framework, which is first to use the contrast limited adaptive histogram equalization (CLAHE) method to enhance the SPAIR image contrast of the spine MRI and then use the non-local means method to remove the noise of the image to ensure that the image contrast is uniform without losing details. We employ the Information Entropy (IE), Peak signal-to-noise ratio (PSNR), and feature similarity index measure (FSIM) to quantify image quality after enhancement by the composite framework. CONCLUSION: The outcomes of the experiments' output images and quantitative data indicate that our composite framework is better than others.

Assessment of the induced effect of selected iron hydroxysulfates biosynthesized using Acidithiobacillus ferrooxidans for biomineralization of acid mine drainage.

Soluble iron and sulfate in acid mine drainage (AMD) can be greatly removed through the formation of minerals facilitated by seed crystals. However, the difference in the effects of jarosite and schwertmannite as endogenous seed crystals to induce AMD mineralization remains unclear. This paper intends to study the effect of Fe2+ oxidation and Fe3+ mineralization in the biosynthesis of minerals using different addition amounts and methods of jarosite or schwertmannite. The results showed that the addition amount and method of different seed crystals had no effect on the Fe2+ bio-oxidation but would change the Fe3+ mineralization efficiency. With the same amount of seed crystals added, jarosite exhibited a higher capacity to promote Fe3+ mineralization than schwertmannite. Adding seed crystals before the initiation of Fe2+ oxidation (0 h) could significantly promote Fe3+ mineralization efficiency. With the increase of seed crystals, jarosite could not only shorten the time required for mineral synthesis but also improve the final mineral yield, whereas schwertmannite could only shorten the time required for mineral synthesis. When Fe2+ was completely oxidized to Fe3+ (48 h), the supplementary of jarosite could still effectively improve Fe3+ mineralization efficiency, but the addition of schwertmannite no longer affected the final mineralization degree.

Polypropylene microplastics affect the distribution and bioavailability of cadmium by changing soil components during soil aging.

Compared with the widespread and serious heavy metal contamination in soils, microplastic pollution has gained attention only recently. Little is known about how microplastics affect the distribution of heavy metals in soils, especially across soil components level. In this study, a 180-day soil aging experiment and soil density fractionation were performed to investigate the effect of polypropylene (PP) microplastics on the binding behavior of cadmium (Cd) to solid components, i.e. particulate organic matter, organo-mineral complexes (OMC), and mineral. Results showed addition of 2-10% microplastics in soils induced the decomposition of OMC fraction by 10.88-23.10%. Compared to the control, the content of dissolved organic carbon increased, and pH, humic substances, and soil organic matter decreased with microplastics. After 180d of aging, the content of Cd in OMC fraction increased by 17.92%, while microplastics made Cd contents decline by 10.01-19.75%. The impacts strongly depended on the dose and surface characteristic of microplastics. Overall, PP microplastics increased the concentration of bioavailable Cd in soils via decreasing soil retention of Cd by the OMC fraction. These findings based on the solid components level will provide a new perspective for understanding microplastics effects on soil systems and pollutants.

A novel approach for treating acid mine drainage by forming schwertmannite driven by a combination of biooxidation and electroreduction before lime neutralization.

Acid mine drainage (AMD) contains abundant iron, sulfates, and various metal ions, and it causes environmental pollution. The traditional AMD lime neutralization forms a layer of iron hydroxide and gypsum on the surface of the lime particles, preventing continuous reaction and leading to excessive lime addition and neutralized sludge production. In this study, an approach for treating AMD using a cyclic process of biooxidation and electroreduction before lime neutralization was proposed, in which the Fe2+ in AMD was oxidized to Fe3+ and induced to form schwertmannite through Acidithiobacillus ferrooxidans. The remaining Fe3+ was reduced to Fe2+ using an electric field. After three biooxidation and two electroreduction cycles, 98.2% of Fe and 62.4% of SO42- in AMD precipitated as schwertmannite (Fe8O8(OH)5.16(SO4)1.37). The yield of schwertmannite reached 33.98 g/LAMD, with a high specific surface area of 112.59 m2/g. The lime dosage and sludge yield of the treated AMD in the subsequent neutralization stage (pH = 7.00) decreased by 85.0% and 74.5%, respectively, than those of raw AMD. The pilot test results showed that the integrated treatment of biooxidation-electroreduction cyclic mineralization and lime neutralization has practical applications.

Trace Metal Lead Exposure in Typical Lip Cosmetics From Electronic Commercial Platform: Investigation, Health Risk Assessment and Blood Lead Level Analysis.

Lead (Pb) in lipstick products has become an increasing concern, which can cause safety problems to human body directly with diet. To investigate the Pb exposure and potential health risk level of typical popular lip cosmetics in Chinese e-commerce market, Python crawler was introduced to identify and select 34 typical popular lip cosmetics, including 12 lipsticks, 13 lip glosses, and 9 lip balms. And then this study used ICP-MS to determine the content of Pb. Furthermore, the ingestion health risk assessment method issued by United States Environmental Protection Agency (USEPA) and Monte Carlo simulation algorithm were applied to assess the probabilistic health risks of adults exposure. Finally, taking the possible exposure of children contacting with lip products, the health risk assessment of children blood Pb was carried out. The results showed that the concentration of Pb in lip products ranged from 0 to 0.5237 mg/kg, which was far lower than the limit set by various countries. The probabilistic non-carcinogenic risks and carcinogenic risks were 4.93 ×10-7~2.82 ×10-3 and 1.68 ×10-12~9.59 ×10-9, respectively, which were in an acceptable level. The results of blood Pb assessment suggested that the Pb content of lip cosmetics had no obvious influence on blood Pb concentration of children, and background Pb exposure is the main factor affecting children's blood Pb level (BLL). Overall, the samples of lip products are selected by Python crawler in this study, which are more objective and representative. This study focuses on deeper study of Pb, especially for the health risk assessment of blood Pb in children exposed to lip products. These results perhaps could provide useful information for the safety cosmetics usage for people in China and even the global world.

Rethinking of Environmental Health Risks: A Systematic Approach of Physical-Social Health Vulnerability Assessment on Heavy-Metal Exposure through Soil and Vegetables.

In the field of environmental health risk assessment and management research, heavy metals in soil are a constant focus, largely because of mining and metallurgical activities, and other manufacturing or producing. However, systematic vulnerability, and combined research of social and physical vulnerability of the crowd, have received less attention in the research literature of environmental health risk assessment. For this reason, tentative design modelling for comprehensive environmental health vulnerability, which includes the index of physical and social vulnerability, was conducted here. On the basis of experimental data of heavy-metal pollution in soil and vegetables, and population and societal survey data in Daye, China, the physical, social, and comprehensive environmental health vulnerabilities of the area were analyzed, with each village as an evaluation unit. First, the polluted and reference areas were selected. Random sampling sites were distributed in the farmland of the villages in these two areas, with two sampling sites per village. Then, 204 vegetable samples were directly collected from the farmland from which the soil samples had been collected, composed of seven kinds of vegetables: cowpea, water spinach, amaranth, sweet potato leaves, tomato, eggplant, and pepper. Moreover, 400 questionnaires were given to the local residents in these corresponding villages, and 389 valid responses were obtained. The results indicated that (1) the average physical vulnerability values of the population in the polluted and reference areas were 3.99 and 1.00, respectively; (2) the village of Weiwang (WW) had the highest physical vulnerability of 8.55; (3) vegetable intake is exposure that should be paid more attention, as it contributes more than 90% to physical vulnerability among the exposure pathways; (4) arsenic and cadmium should be the priority pollutants, with average physical vulnerability value contributions of 63.9% and 17.0%, respectively; (5) according to the social vulnerability assessment, the village of Luoqiao (LQ) had the highest social vulnerability (0.77); (6) for comprehensive environmental health vulnerability, five villages near mining activities and two villages far from mine-affected area had high physical and social vulnerability, and are the urgent areas for environmental risk management. In order to promote environmental risk management, it is necessary to prioritize identifying vulnerable populations in the village-scale dimension as an innovative discovery.

A critical review on the interactions of microplastics with heavy metals: Mechanism and their combined effect on organisms and humans.

Although individual toxicity of microplastics (MPs) to organism has been widely studied, limited knowledge is available on the interactions between heavy metals and MPs, as well as potential biological impacts from their combinations. The interaction between MPs and heavy metals may alter their environmental behaviors, bioavailability and potential toxicity, leading to ecological risks. In this paper, an overview of different sources of heavy metals on MPs is provided. Then the recent achievements in adsorption isotherms, adsorption kinetics and interaction mechanism between MPs and heavy metals are discussed. Besides, the factors that influence the adsorption of heavy metals on MPs such as polymer properties, chemical properties of heavy metals, and other environmental factors are also considered. Furthermore, potential combined toxic effects from MPs and heavy metals on organisms and human health are further summarized.

The coupling reaction of Fe2+ bio-oxidation and resulting Fe3+ hydrolysis drastically improve the formation of iron hydroxysulfate minerals in AMD.

The oxidation of Fe2+ by Acidithiobacillus ferrooxidans (A. ferrooxidans) in acid mine drainage (AMD) is often accompanied by formation of iron hydroxysulfate minerals, such as schwertmannite and jarosite. This study reported that 80 mmol L-1 of Fe2+ could be completely oxidized by A. ferrooxidans LX5 within 48 h, but only 27.7% of the resultant Fe3+ precipitated to form schwertmannite. However, the conversion efficiency to jarosite was much higher (54.5%). The formation of jarosite lasted 120 h, while only 24 h when conversed to schwertmannite. By constructing a cyclic process of 'Cu-reducing coupled with bio-oxidization', the total Fe in AMD could be fully converted into mineral precipitates. The resultant mineral specie could be regulated simply by control the K+ concentration. Thermodynamically, Fe3+ cannot hydrolyze spontaneously to form schwertmannite due to the positive Gibbs free energy (ΔrGm∘ = 6.63 kJ mol-1) of the reaction. However, if Fe2+ were biologically oxidized by A. ferrooxidans, the resultant Fe3+ could spontaneously form schwertmannite because the aforementioned coupling reaction has a negative Gibbs free energy (ΔrGm∘ = -34.12 kJ mol-1). Even though Fe3+ itself could hydrolyze to form jarosite spontaneously with ΔrGm∘ = -22.20 kJ mol-1, the coupling reaction of Fe2+ bio-oxidation followed by Fe3+ hydrolysis in the presence of K+ could easily promote the formation of jarosite, which exhibited a great negative Gibbs energy (ΔrGm∘ = -67.45 kJ mol-1).

Treatment for lumbar spinal stenosis secondary to ligamentum flavum hypertrophy using percutaneous endoscopy through interlaminar approach: a retrospective study.

BACKGROUND: This paper is to describe percutaneous endoscopy in the treatment of lumbar spinal stenosis secondary to ligamentum flavum hypertrophy targeted and to investigate the efficacy and safety of percutaneous endoscopy in the treatment of this kind of lumbar spinal stenosis in elderly patients. METHOD: A retrospective analysis of 40 elderly patients with lumbar spinal stenosis secondary to ligamentum flavum hypertrophy admitted between January 2016 and January 2018 was performed. According to different surgical methods, they were divided into two groups: the control group and the endoscopy group (interlaminar approach), 20 people per group. There were 9 males and 11 females in the control group; the age of patients was 65.65 ± 4.44 years, and the average disease duration was 4.55 ± 1.85 years. Besides, there were 10 males and 10 females in the endoscopy group; the age of patients was 67.30 ± 4.23 years, and the average disease duration was 4.95 ± 2.04 years. Collect and count surgical-related indicators, preoperative and postoperative radiologic findings, incision visual analog scale (VAS), lumbar and leg pain VAS, lumbar Japanese Orthopaedic Association (JOA), and Oswestry disability index (ODI) scores of all patients. RESULT: A series of surgical indicators (including the operation time, the quantity of bleeding, and postoperative hospital stay) in the endoscopy group was significantly lower than that in the control group (p < 0.05). The incision VAS score in the endoscopy group was also significantly lower than that in the control group at each time after surgery (p < 0.05). Besides, compared with the control group, in the endoscopy group, the leg pain VAS score and lumbar ODI score after surgery were significantly decreased (p < 0.05). Compared with the control group, in the endoscopy group, the lumbar JOA score was significantly higher (p < 0.05). CONCLUSION: Percutaneous endoscopic technique is a small trauma, quick recovery, safe, and effective minimally invasive surgery for patients with lumbar spinal stenosis secondary to ligamentum flavum hypertrophy.

Evodiamine exerts anticancer effects via induction of apoptosis and autophagy and suppresses the migration and invasion of human colon cancer cells.

PURPOSE: Colon cancer ranks as the fourth common type of cancer and is responsible for significant morbidity and mortality throughout the world. Late diagnosis and the rarity of potent and safer chemotherapeutic drugs and efficient therapeutic targets create severe obstacle in the treatment of colon cancer. This study was undertaken to examine the anticancer effects of Evodiamine against human colon cancer cells. METHODS: The proliferation rate of the SW480 colon cancer cells was monitored by MTT assay. Apoptosis was detected by Annexin V/propidium iodide (PI) and acridine orange (AO)/ethidium bromide (EB) staining. Transmission electron microscopy (TEM) was used for detection of autophagy. Cell migration and invasion was detected by wound healing and transwell assays, respectively. Protein expression was determined by western blotting. RESULTS: Evodiamine suppressed the proliferation of the SW480 colon cancer cells and exhibited an IC50 of 10 µM. The cytotoxic effects of Evodiamine were found to be comparatively lower against the normal CDD-18Co colon cells as evidenced from the IC50 of 100 µM. AO/EB staining showed that Evodiamine caused apoptosis of the SW480 cells and the percentage of the apoptotic SW480 cells increased with increase in the Evodiamine concentration as indicated by annexin V/PI staining. Evodiamine-induced apoptosis was also accompanied by upregulation of caspase-3 and Bax and suppression of Bcl-2. TEM analysis showed that Evodiamine also activated autophagy in the SW480 cells by enhancing the expression of LC3 II and Beclin 1. The wound assay showed that Evodiamine suppressed the migration of the SW480 cells. Evodiamine also reduced the invasion potential of the SW480 cells as suggested by the transwell assay. CONCLUSION: The findings of the present study suggest that Evodiamine is a potent anticancer agent and may prove beneficial in the development of systemic therapy of colon cancer.

Using polyvinyl alcohol to improve the deacidification performance of titanium white waste acid: Pilot tests.

Titanium white waste acid (TWWA) is strongly acidic, and has high metatitanic acid (TiO(OH)2) and n-hexane (C6H14) content. In this study, the effects of polyvinyl alcohol (PVA) on the modification of TWWA deacidification were evaluated via pilot testing. The results showed that the PVA solution can significantly improve the deacidification performance of TWWA. The TWWA specific resistance to filtration (SRF) decreased from the initial 2.42 × 1013 m/kg to 1.80 × 1012 m/kg when 2% PVA solution was added at 25% (v/v). Furthermore, the amount of filter press-processed TWWA increased by 3.56 m3 relative to the control, and the moisture content of titanium white slag was only 42.02% after deacidification. In addition, distillation and phase separation was demonstrated to efficiently separate C6H14 and hydrochloric acid (HCl) from the mixed filtrate. Moreover, titanium white slag was converted into rutile after 60 min when the calcination temperature was 900 °C, with the titanium dioxide (TiO2) purity of rutile reaching 91.83%. Accordingly, the TWWA recycling process proceeded as follows: PVA modification, solid-liquid separation, filtrate distillation and phase separation, and titanium white slag calcination. Our findings demonstrate that this process has unique practical application value.

Comparison of the Biological and Chemical Synthesis of Schwertmannite at a Consistent Fe2+ Oxidation Efficiency and the Effect of Extracellular Polymeric Substances of Acidithiobacillus ferrooxidans on Biomineralization.

Schwertmannite is an environmental mineral material that can promote the natural passivation of heavy metal elements, thereby reducing environmental pollution from toxic elements. However, the fundamental reason for the difference between the chemically (H2O2-FeSO4) and biologically (Acidithiobacillus ferrooxidans-FeSO4) synthesized schwertmannite is still unclear. In this study, X-ray diffraction, scanning electron microscopy, the Brunauer⁻Emmett⁻Teller method, and X-ray fluorescence spectrometry were used to compare the structure, specific surface area, and elemental composition of schwertmannite synthesized by biological and chemical methods. The removal capacity of As(III) by the two kinds of schwertmannite and the effects of extracellular polymeric substances (EPS) on biogenetic schwertmannite were also investigated. At a consistent Fe2+ oxidation efficiency, the chemical method synthesized more schwertmannite than the biological method over a 60-h period. The biosynthesized schwertmannite had a "chestnut shell" shape, with a larger particle size and specific surface than the chemically synthesized schwertmannite, which was relatively smooth. The saturated adsorption capacities of the biologically and chemically synthesized schwertmannite were 117.0 and 87.0 mg·g-1, respectively. After exfoliation of the EPS from A. ferrooxidans, the biosynthesized schwertmannite displayed a "wool ball" shape, with rough particle surfaces, many microporous structures, and a larger specific surface area. The schwertmannite yield also increased by about 45% compared with that before exfoliation, suggesting that the secretion of EPS by A. ferrooxidans can inhibit the formation of schwertmannite.

Boswellic acid exerts potent anticancer effects in HCT-116 human colon cancer cells mediated via induction of apoptosis, cell cycle arrest, cell migration inhibition and inhibition of PI3K/AKT signalling pathway.

PURPOSE: Boswellic acid is an important plant-derived natural product with tremendous pharmacological potential and has been reported to inhibit the growth of several types of cancer cells. In this study we report the anticancer activity of boswellic acid against human colon cancer cells via induction of apoptosis, cell cycle arrest and inhibition of cell migration and PI3K/AKT signalling pathway. METHODS: The antiproliferative effects of boswellic acid were assessed by MTT assay using different doses of the drug. The apoptotic effects were studied by DAPI and annexin V/PI staining assays, and cell cycle distribution was studied by flow cytometry. The effects of the drug on PI3K/AKT protein expression were studied using western blot analysis. RESULTS: The results of this study showed that boswellic acid suppresses the growth of HCT-116 colon cancer cells. The anticancer effects were found to be dose-dependent and the IC50 value was 15 µM against the HCT-116 colon cancer cells. The inhibition of growth of these cancer cells was mainly due to apoptosis and G2/M cell cycle arrest. Besides, boswellic acid altered the Bax/Bcl-2 ratio in the HCT-116 cancer cells and inhibited their migration as indicated by the cell migration assay. It was observed that boswellic acid decreased the expression of p-PI3K and p-AKT in a concentration- dependent manner. However, the expression of PI3K and AKT remained almost unaltered. CONCLUSION: In conclusion, these results clearly suggest that boswellic acid could be employed in the treatment of colon cancer provided further in vivo and other in depth experiments are done.

Heavy metal contamination in soils and vegetables and health risk assessment of inhabitants in Daye, China.

Objective This study was performed to evaluate the state of heavy metal contamination in soil and vegetables and assess the health risk of inhabitants in the mine-affected area and area far from the mine (reference area) in Daye, China. Methods The heavy metal concentrations in soil and vegetable samples were detected by inductively coupled plasma mass spectrometry. Residents' exposure parameters were obtained through a questionnaire survey. A health risk assessment model recommended by the United States Environmental Protection Agency was used to evaluate the residents' risk of oral exposure. Results The copper, lead, cadmium, and arsenic concentrations in soil and in vegetables were higher in the mine-affected area than in the reference area. The health risk of residents in the reference area was within the acceptable range (hazard index < 1, carcinogen risk < 10-4). In the contaminated area, however, the mean hazard index was 2.25 for children and 3.00 for adults, and the mean carcinogen risk was 4.749 × 10-4 for children and 0.587 × 10-4 for adults. Conclusions Potential health risks exist for inhabitants near the mine area. Cadmium and arsenic should be paid more attention as risk sources.

Evaluation and optimization of a new microbial enhancement plug-flow ditch system for the pretreatment of acid mine drainage: semi-pilot test.

Acid mine drainage (AMD) is typically characterized by low pH, a high concentration of sulfate and dissolved heavy metals. Therefore, it is of practical significance to promote the transformation of soluble Fe and SO4 2- into iron hydroxysulfate minerals by biomineralization of Acidithiobacillus ferrooxidans. This enhances the lime neutralization efficiency of AMD by reducing the production of ferric hydroxide and waste gypsum. In this study, a new microbial enhanced plug-flow ditch reaction system was developed for the pretreatment of AMD on a semi-pilot scale. System stability under different hydraulic retention times (HRTs) was examined and the effects of microbe enhancement-lime neutralization technology and direct lime neutralization technology were compared. The bio-oxidation efficiency of Fe2+ (5 g L-1) reached 100% in some parts of the system when HRT was 3 and 2 days, and the time taken to reach steady state was 6 and 4 days, respectively. When the HRT was 1 day, the reaction system had operated for 4 days before the equilibrium was lost. At the optimum HRT (2 days) and after the system was stable, the average precipitation rate of total Fe was 53.62% and the average removal rate of As(iii) was 17.27%. Following microbial enhanced pretreatment, the amount of lime required and waste residues generated for AMD neutralization decreased by 75.00% and 85.25%, respectively. This result supports the application of microbial enhancement-lime neutralization passive treatment technology for AMD.

Initial pH and K+ concentrations jointly determine the types of biogenic ferric hydroxysulfate minerals and their effect on adsorption removal of Cr(VI) in simulated acid mine drainage.

It is of practical significance to promote the transformation of Fe in acid mine drainage (AMD) into ferric hydroxysulfate minerals with strong ability to remove heavy metals or metalloids. To investigate the types of biogenic ferric hydroxysulfate minerals generated in AMD by Acidithiobacillus ferrooxidans (A. ferrooxidans), different pH and K+ concentrations are tested for the formation of precipitates in media containing 160 mmol/L Fe2+. The Cr(VI) removal efficiencies of ferric hydroxysulfate minerals in AMD with different acidities are also compared. Results indicate that the mineralizing abilities of the initial pH levels (pH 3.0 > pH 2.5 > pH 2.0) and K+ concentrations (53.3 mmol/L > 3.2 mmol/L ≈ 0.8 mmol/L) differ, with cumulative Fe precipitation efficiencies of 58.7%, 58.0%, and 44.2% (K+ = 53.3 mmol/L), and 58.7%, 29.9%, and 29.6% (pH 3.0) after 96 h of A. ferrooxidans incubation, respectively. X-ray diffraction indicates that K-jarosites are formed in the treatments n(Fe)/n(K) = 0.1 and 3 at pH 2.0-3.0, while only schwertmannite is generated in a system of pH 3.0 and n(Fe)/n(K) = 200. X-ray photoelectron spectroscopy reveals that HCrO4 - may be adsorbed as an inner-sphere complex on schwertmannite when the AMD pH is 3.0.

[Inhibition of Low Molecular Organic Acids on the Activity of Acidithiobacillus Species and Its Effect on the Removal of Heavy Metals from Contaminated Soil].

Application of organic fertilizer can reduce the solubility and bioavailability of heavy metals in contaminated soil, but in the flooded anaerobic environment, organic fertilizer will be decomposed to produce a large number of low molecular organic acids, which can inhibit the biological activity of Acidithiobacillus species. Batch cultures studies showed that the monocarboxylic organic acids including formic acid, acetic acid, propionic acid, and butyric acid exhibited a marked toxicity to Acidithiobacillus species, as indicated by that 90% of inhibitory rate for Fe2 and So oxidation in 72 h were achieved at extremely low concentrations of 41.2 mg · L⁻¹, 78.3 mg · L⁻¹, 43.2 mg · L⁻¹, 123.4 mg · L⁻¹ and 81.9 mg 230. 4 mg · L⁻¹, 170.1 mg · L⁻¹, 123.4 mg · L⁻¹ respectively. Of these organic acids, formic acid was the most toxic one as indicated by that Fe2 and So oxidation was almost entirely inhibited at a low concentration. In addition, it was found that Acidithiobacillus ferrooxidans was more sensitive to low molecular organic acids than Acidithiobacillus thiooxidans. What's more, there was little effect on biological acidification process of heavy metal contaminated soil when organic acids were added at initial stage (Oh), but it was completely inhibited when these acids were added after 12 h of conventional biological acidification, thus decreasing the efficiency of heavy metals dissolution from soil.

Heavy metals in road dust from Xiandao District, Changsha City, China: characteristics, health risk assessment, and integrated source identification.

The physicochemical properties and the contents of metals (Cu, Zn, Pb, Cd, Cr, and Fe) in 51 road dust samples from Xiandao District (XDD) were investigated. Enrichment factor (EF), multivariate statistics, geostatistics, and health risk assessment model were adopted to study the spatial pollution pattern and to identify the priority pollutants and regions of concern and sources of studied metals. The mean EFs revealed the following order: Cd > Zn ≈ Pb ≈ Cu > Cr. For non-carcinogenic effects, the exposure pathway which resulted in the highest levels of exposure risk for children and adults was ingestion, followed by dermal contact and inhalation. Hazard index (HI) values for the studied metals at each site were within the safe level of 1 except maximum HI Cr (1.08) for children. The carcinogenic risk (CR) for Cd and Cr at each site was within the acceptable risk level (1E-06) except CR Cr (1.08E-06) for children in the road intersection between the Changchang highway and the Yuelin highway. Cr was identified as the priority pollutant followed by Pb and Cd with consideration of the local population distribution. Spatially, northwest and northeast of XDD were regarded as the priority regions of concern. Results based on the proposed integrated source identification method indicated that Pb was probably sourced from traffic-related sources, Cd was associated with the dust organic material mainly originated from industrial sources, and Cr was mainly derived from both sources.