Efficient removal of heavy metals from aqueous solutions using Mn-doped FeOOH: Performance and mechanisms.

The treatment of heavy metal ion contamination in aquatic ecosystems has been a growing global concern for centuries. Iron oxide nanomaterials are effective in heavy metals removal, but are frequently challenging due to the precipitation of Fe(III) and poor reusability. To improve the removal of heavy metals by iron hydroxyl oxide (FeOOH), the iron-manganese oxide material (FMBO) was separately prepared to remove Cd(II), Ni(II), and Pb(II) in individual and multiple systems. Results revealed that the loading of Mn enlarged the specific surface area and stabilized the structure of FeOOH. FMBO achieved 18%, 17%, and 40% higher removal capacities of Cd(II), Ni(II), and Pb(II) than that of FeOOH, respectively. Besides, mass spectrometry analysis demonstrated that the surface hydroxyls (-OH, Fe/Mn-OH) of FeOOH and FMBO provided the active sites for metal complexation. Fe(III) was reduced by Mn ions and further complexed with heavy metals. Further density functional theory calculations revealed that Mn loading led to the structural reconstruction of the electron transfer, which significantly promoted stable hybridization. This confirmed that FMBO improved the properties of FeOOH and was efficient for removing heavy metals from wastewater.

Improving soil fertility by driving microbial community changes in saline soils of Yellow River Delta under petroleum pollution.

It is promising to use indigenous microorganisms for fertility improvement in petroleum-contaminated coastal soil. As a result, the microbial community and physicochemical property are the base for the restoration. For the detailed information, the Phragmites Communis (P), Chinese Tamarisk (C), Suaeda salsa (S), and new Bare Land (B) soil of Yellow River Delta was 90 g in 100 mL sterile bottles simulated at 25 °C with soil: petroleum = 10:1 in the incubator for four months. The samples were detected at 60 and 120 days along with untreated soil and aged Oil Sludge (O) as control. The results showed that all the samples were alkaline (pH 7.99-8.83), which the salinity and NO3- content of incubate soil followed the in situ samples as P (1.09-1.72‰, 8.02-8.17 mg kg-1), C (10.61-13.79‰, 5.99-6.07 mg kg-1), S (10.19-12.43‰, 3.64-4.22 mg kg-1), B (31.85-32.45‰, 3.56-3.72 mg kg-1) and O (31.61-34.30‰, 0.89-0.90 mg kg-1). NO3- and organic carbon decreased after incubation, which the polluted samples (86.63-92.63 g kg-1) still had higher organic carbon than untreated ones with more NH4+ consumption. The high-throughput sequence results showed that the Gammaproteobacteria and Alphaproteobacteria were dominant in all samples, while sulfate reducting bacteria Alphaproteobacteria decreased at 120 days. Meanwhile, the electroactive Gammaproteobacteria might symbiosis with Methanosaetaceae and Methanosarcinaceae, degrading petroleum after electron receptors depletion. Nitrososphaeraceae and Nitrosopumilaceae oxidise NH4+ to NO2- for intra-aerobic anaerobes and denitrifying bacteria producing oxygen for biodegradation in polluted Phragmites Communis soil. The halotolerant Halomicrobiaceae and Haloferacaceae predominated in saline Chinese Tamarisk, Suaeda Salsa and Bare Land, which were potential electroactive degradater. As the ageing sludge formed, the hydrogen trophic methanogens Methanothermobacteraceae (73.90-92.72%) was prevalent with the petroleum pollution. In conclusion, petroleum initiated two-phase in the sludge forming progress: electron acceptor consumption and electron transfer between degradater and methanogens. Based on the results, the domestic sewage N, P removal coupling and electron transport will be the basement for polluted soils fertility improvement.

Anaerobic-petroleum degrading bacteria: Diversity and biotechnological applications for improving coastal soil.

Due to the industrial emissions and accidental spills, the critical material for modern industrial society petroleum pollution causes severe ecological damage. The prosperous oil exploitation and transportation causes the recalcitrant, hazardous, and carcinogenic sludge widespread in the coastal wetlands. The costly physicochemical-based remediation remains the secondary and inadequate treatment for the derivatives along with the tailings. Anaerobic microbial petroleum degrading biotechnology has received extensive attention for its cost acceptable, eco-friendly, and fewer health hazards. As a result of the advances in biotechnology and microbiology, the anaerobic oil-degrading bacteria have been well developing to achieve the same remediation effects with lower operating costs. This review summarizes the advantages and potential scenarios of the anaerobic degrading bacteria, such as sulfate-reducing bacteria, denitrifying bacteria, and metal-reducing bacteria in the coastal area decomposing the alkanes, alkenes, aromatic hydrocarbons, polycyclic aromatic, and related derivatives. In the future, a complete theoretical basis of microbiological biotechnology, molecular biology, and electrochemistry is necessary to make efficient and environmental-friendly use of anaerobic degradation bacteria to mineralize oil sludge organic wastes.

Bacterial community structure of aged oil sludge contaminated soil revealed by illumina high-throughput sequencing in East China.

Screening of the dominant or core oil resistant bacteria in Aged Oil Sludge (AOS) contaminated soil in Daqing and Shengli oilfields (DQ and SL) in China was investigated through High-Throughput Sequencing method. Enhanced total organic carbon (TOC, 12.53 to 28.35 g/kg in DQ and 3.07 to 4.97 g/kg in SL) and total petroleum hydrocarbons (TPHs, 21 to 2837 mg/mg in DQ and 13 to 1558 mg/kg in SL) were observed. The internal transcribed spacer (ITS) sequencing by Illumine Miseq platform at each taxonomic level revealed the notable toxicological effect of AOS on the diversity and community structure of bacteria. In this study, sequence analyses showed 77-89% and 92-98% reduction of Firmicutes at phylum level in DQ and SL respectively after treated with AOS. Enhanced universal gene location was observed in Proteobacteria, Actinobacteria, Gemmatimonadetes and Bacteroidetes in DQ and SL. The universal dominant family in the two oilfields was anaerolineaceae. At the genus level, Algiphilus in DQ and Pseudomonas in SL were the majority respectively. In total, 3 negligible genera (Perlucidibaca, Alcanivorax and Algiphilus) in DQ and 13 negligible genera (Salinisphaera, Microbulbifer and Idiomarina, et al.,) in SL were significantly enriched after oil treatment indicating their possible role in the attenuation of petroleum hydrocarbons.

Oil crop genetic modification for producing added value lipids.

Plant lipids, mainly stored in seeds and other plant parts, are not only a crucial resource for food and fodder but are also a promising alternative to fossil oils as a chemical industry feedstock. Oil crop cultivation and processing are always important parts of agriculture worldwide. Vegetable oils containing polyunsaturated fatty acids, very long chain fatty acids, conjugated fatty acids, hydroxy fatty acids and wax esters, have outstanding nutritional, lubricating, surfactant, and artificial-fibre-synthesis properties, amongst others. Enhancing the production of such specific lipid components is of economic interest. There has been a considerable amount of information reported about plant lipid biosynthesis, including identification of the pathway map of carbon flux, key enzymes (and the coding genes), and substrate affinities. Plant lipid biosynthesis engineering to produce special oil compounds has become feasible, although until now, only limited progress has been made in the laboratory. It is relatively easy to achieve the experimental objectives, for example, accumulating novel lipid compounds in given plant tissues facilitated by genetic modification. Applying such technologies to agricultural production is difficult, and the challenge is to make engineered crops economically attractive, which is impeded by only moderate success. To achieve this goal, more complicated and systematic strategies should be developed and discussed based on the relevant results currently available.

Effects of Aged Oil Sludge on Soil Physicochemical Properties and Fungal Diversity Revealed by High-Throughput Sequencing Analysis.

The oilfield soil was contaminated for years by large quantities of aged oil sludge generated in the petroleum industry. In this study, physicochemical properties, contents of main pollutants, and fungal diversity of the aged oil sludge-contaminated soil were analyzed. Results revealed that aged oil sludge significantly changed physical and chemical properties of the receiving soil and increased the contents of main pollutants (petroleum hydrocarbons and heavy metals) in soil. Meanwhile, the internal transcribed spacer (ITS) sequencing by Illumina Miseq platform at each taxonomic level demonstrated that the toxicological effect of oil pollutants obviously influenced the fungal diversity and community structure in soil. Moreover, it was found that the presence of three genera (Cephalotheca, Lecanicillium, and Septoriella) appeared in aged oil sludge-contaminated soil. And oil pollutants promoted the growth of certain genera in Ascomycota (70.83%) and Basidiomycota (10.78%), such as Venturia, Alternaria, and Piloderma. Nevertheless, the growth of Mortierella (9.16%), Emericella (6.02%), and Bjerkandera (0.00%) was intensively limited. This study would aid thorough understanding of microbial diversity in oil-contaminated soil and thus provide new point of view to soil bioremediation.

Soil Microbial Community Structure and Diversity around the Aging Oil Sludge in Yellow River Delta as Determined by High-Throughput Sequencing.

Microorganisms are sensitive indicators of edaphic environmental variation. The Illumina MiSeq sequencing technology was used to analyze soil bacterial community diversity around an aging oil sludge in the Yellow River Delta. The alpha diversity index of soil bacterial community results (Ace, Chao, Shannon, and Simpson) determined that bacterial community diversity sampling within the scope of a 20 cm radius from the center of an aging oil sludge spot showed the most abundant diversity. The level of diversity distributed symmetrically with radial direction from the center of the aging oil sludge spot. Over the distance of 100 m from the center, bacterial community diversity tends to be monotonous, with small differences especially in the horizontal direction underground. The alpha-diversity indicators also showed that the bacterial diversity of samples were close under the aging oil sludge. In addition, the aging oil sludge inhibited the growth of bacteria compared with the referenced unpolluted soil sample and also increased the diversities of soil bacteria. At the phylum level, the Proteobacteria, Chloroflexi, and Actinobacteria existing in the aging oil sludge-contaminated wetland soil constituted a larger proportion of the community, while the proportion of Firmicute was relatively less. On the contrary, Firmicute showed the highest content of 63.8% in the referenced soil. Under the genus level and family level, the corresponding strains that resisted the aging oil sludge were selected. According to the bacterial diversity analysis, the basic structure of the bacterial community which could be used for remediation of aging oil sludge-contaminated soil was also developed.

The effects of charge compensation on photoluminescence properties of a new green-emitting ZnB2O4:Tb3+ phosphor.

Charge compensation is an effective way to eliminate charge defects and improve the luminescent intensity of phosphors. In this paper, a new green-emitting phosphor ZnB(2)O(4):Tb(3+) was prepared by solid-state reaction at 750 °C. The effects of Tb(3+) doping content and charge compensators (Li(+), Na(+) or K(+)) on photoluminescence properties of ZnB(2)O(4):Tb(3+) were investigated. X-ray powder diffraction analysis confirms the sample has cubic structure of ZnB(2)O(4). The excitation and emission spectra indicate that this phosphor can be excited by near ultraviolet light at 378 nm, and exhibits bright green emission with the highest peak at 544 nm corresponding to the (5)D4 → (7)F5 transition of Tb(3+). The critical quenching concentration of Tb(3+) in ZnB(2)O(4) host is 8 mol%. The results of charge compensation show that the emission intensity can be improved by Na(+) and K(+). Specifically, K(+) is the optimal one for ZnB(2)O(4):Tb(3+).

Efficient stabilization of arsenic migration and conversion in soil with surfactant-modified iron-manganese oxide: Environmental effects and mechanistic insights.

The use of iron-manganese oxide (FMO) as a promising amendment for remediating arsenic (As) contamination in soils has gained attention, but its application is limited owing to agglomeration issues. This study aims to address agglomeration using surfactant-modified FMO and investigate their stabilization behavior towards As and resulting environmental changes upon amendments. The results confirmed the efficacy of surfactants and demonstrated that cetyltrimethylammonium-bromide-modified FMO significantly reduced the leaching concentration of As by 92.5 % and effectively suppressed the uptake of As by 85.8 % compared with the control groups. The ratio of the residual fraction increased from 30.5-41.6 % in unamended soil to 67.9-69.2 %. The number of active sites was through the introduction of surfactants and immobilized As via complexation, ion exchange, and redox reactions. The study also revealed that amendments and the concentration of As influenced the soil physicochemical properties and enriched bacteria associated with As and Fe reduction and changed the distribution of C, N, Fe, and As metabolism genes, which promoted the stabilization of As. The interactions among cetyltrimethylammonium bromide, FMO, and microorganisms were found to have the greatest effect on As immobilization.

Remediation of oil-polluted soil using anionic and non-ionic composite biosurfactants.

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.

Biochar-amended composting of lincomycin fermentation dregs promoted microbial metabolism and reduced antibiotic resistance genes.

Improper disposal of antibiotic fermentation dregs poses a risk of releasing antibiotics and antibiotic resistant bacteria to the environment. Therefore, this study evaluated the effects of biochar addition to lincomycin fermentation dregs (LFDs) composting. Biochar increased compost temperature and enhanced organic matter decomposition and residual antibiotics removal. Moreover, a 1.5- to 17.0-fold reduction in antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) was observed. Adding biochar also reduced the abundances of persistent ARGs hosts (e.g., Streptomyces, Pseudomonas) and ARG-related metabolic pathways and genes (e.g., ATP-binding cassette type-2 transport, signal transduction and multidrug efflux pump genes). By contrast, compost decomposition improved due to enhanced metabolism of carbohydrates and amino acids. Overall, adding biochar into LFDs compost reduced the proliferation of ARGs and enhanced microbial community metabolism. These results demonstrate that adding biochar to LFDs compost is a simple and efficient way to decrease risks associated with LFDs composting.

Abundance, diversity, and community structure of comammox cladeA in sediments of China's offshore continental shelf.

Nitrification is an important link for environmental nitrogen cycling, the appearance of comammox updates our traditional cognition about nitrification. Yet comammox has been poorly studied in marine sediments. This study explored the differences in abundance, diversity, community structure of comammox cladeA amoA in the sediments from different offshore areas of China (the Bohai Sea (BS), the Yellow Sea (YS), and the East China Sea (ECS)) and revealed the main driving factors. The abundance of comammox cladeA amoA was 8.11 × 103-4.96 × 104, 2.85 × 104-4.18 × 104, and 5.76 × 103-4.91 × 104 copies/g dry sediment in BS, YS, and ECS, respectively. The OTU (operational taxonomic units) numbers of comammox cladeA amoA in the BS, YS, and ECS were 4, 2, and 5 respectively. There were negligible differences in the abundance and diversity of comammox cladeA amoA among the sediments of the three seas. The subclade of comammox cladeA amoA, cladeA2 is the dominant comammox flora in the offshore area sediments of China. Noticeable differences in the community structure of comammox were observed among these three seas, where the relative abundance of cladeA2 in comammox was 62.98 %, 66.24 %, and 100 % in ECS, BS, and YS respectively. pH was found as the main factor affecting the abundance of comammox cladeA amoA and showed a significant positive correlation (p < 0.05). The diversity of comammox decreased with the increase of salinity (p < 0.05). NO3--N is the main factor affecting the community structure of comammox cladeA amoA.

A biomimetic design for efficient petrochemical spill disposal: CoFe-PBA modified superhydrophobic melamine sponge with mechanical/chemical durability and low fire risk.

Due to frequent petrochemical spills, environmental pollution and the threat of secondary marine fires have arisen, necessitating an urgent need for petrochemical spill treatment strategies with high-performance oil-water separation capabilities. To address the challenges of poor durability, instability in hydrophobic conditions, and difficulty in absorbing high-viscosity crude oil associated with hydrophobic absorbent materials, the authors of this study took inspiration from the unique micro and nanostructures of springtails' water-repellent skin. We engineered a superhydrophobic melamine sponge using interfacial assembly techniques designated as Si@PBA@PDA@MS. This material demonstrated improved mechanical and chemical durability, enhanced photothermal performance, and reduced fire risk. The metal-organic framework (MOF)-derived cobalt-iron Prussian blue analog (CoFe-PBA) was firmly anchored to the sponge framework by the chelation of cobalt ions using polydopamine (PDA). The results demonstrated that Si@PBA@PDA@MS demonstrated excellent superhydrophobicity (WCA=163.5°) and oil absorption capacity (53.4-97.5 g/g), maintaining high durability even after 20 cycles of absorption-squeezing. Additionally, it could still exhibit excellent mechanical properties, hydrophobic stability, and absorption performance across a wide temperature range (0-100 °C), pH range (1-14), and high compression strength (ε = 80%), with excellent mechanical/chemical durability. Furthermore, Si@PBA@PDA@MS demonstrated remarkable photothermal performance and low fire risk, offering efficient, safe, and sustainable practical value for effective petrochemical spill treatment.

MOF-derived LDH modified flame-retardant polyurethane sponge for high-performance oil-water separation: Interface engineering design based on bioinspiration.

Frequent petrochemical spill accidents and secondary fire hazards have threatened the ecological environment and environmental safety. The traditional purification technology has the problems of high energy consumption and secondary pollution, which also brings new challenges to spill disposal. Herein, we demonstrate a biomimetic structure-based flame-retardant polyurethane (PU) sponge (FPUF@MOF-LDH@HDTMS) for continuous oil-water separation. Inspired by desert beetle and lotus leaf, the biomimetic micro-nano composite structure was constructed by in-situ growth of metal-organic framework-derived layered double hydroxide (MOF-LDH) on the surface of the PU sponge. After grafting MOF-LDH with hexadecyltrimethoxysilane, FPUF@MOF-LDH@HDTMS showed excellent superhydrophobic/superoleophilic performance (water contact angle=153° and oil contact angle=0°). FPUF@MOF-LDH@HDTMS can easily and quickly adsorb oily liquids suspended/settled in the water thanks to the unique bionic structure. FPUF@MOF-LDH@HDTMS has excellent oil/organic solvents absorption capacity; even after 20 cycles of use still maintains high adsorption capacity. More importantly, the continuous oil-water separation through FPUF@MOF-LDH@HTMS has achieved a separation efficiency of up to 99.1%. In addition, the bionic superhydrophobic sponge has excellent flame retardancy, which reduces the possibility of secondary fire caused by PU sponges. Thus, the biomimetic micro-nano composite structure provides a new design strategy for the more high-performance oil-water separation sponges.

Abundance, characteristics and risk assessment of microplastics in aquatic sediments: A comparative study in the Yellow River and Yellow Sea.

The occurrence of microplastics (MPs) in aquatic ecosystems has become an increasingly serious threat to public health. Marine sediments are considered the final recipients of all microplastic pollution from inland rivers, however, whether and how the MPs differ in these two ecosystems remains poorly known due to the divergent MPs detection methods employed in previous studies. Here, we investigated the abundance, size, and types of MPs in sediment samples from the Yellow River and Yellow Sea using laser direct infrared (LDIR), and assessed their ecological risks. The abundance of MPs in the Yellow Sea is 2.9 times higher than that in the Yellow River, with an average abundance of 54813.2 ± 19355.9 and 18780.2 ± 9951.8 particles·kg-1 (dry sediment), respectively. Notably, the predominant polymer types in both sediment environments were silicone, fluororubber, and polypropylene (PP). MPs with sizes < 100 µm accounted for > 90 % of the total MPs number. Risk assessment demonstrated all the sediment environments exhibited high ecological risks. The dominance of small MPs highlighted the importance of using a method with high resolution to delineate the truthful status of MP pollution.

Recent advances in application of iron-manganese oxide nanomaterials for removal of heavy metals in the aquatic environment.

Heavy metal pollution has a serious negative impact on the ecological environment and human health due to its toxicity, persistence, and non-biodegradable properties. Among the technologies applied in heavy metals removal, adsorption has been widely used as the most promising method because of its simple operation, high removal efficiency, strong applicability, and low cost. Iron-manganese oxide nanomaterials, as an effective absorbent, have attracted wide attention due to their simple preparation, wide material sources, and lower ecological impact. So far, no quantitative investigation has been conducted on the preparation and application of iron-manganese oxide nanomaterials in heavy metals removal. This review discussed the preparation methods and characteristics of iron­manganese oxide nanomaterials over the past decade and provided some basic information for the improvement of preparation methods. The physicochemical properties of iron­manganese oxide nanomaterials and environmental conditions are regarded as important factors that affect the removal efficiency of heavy metals. In addition, the removal mechanisms of heavy metals in aqueous solution with iron­manganese oxide nanomaterials were mainly included redox, complex precipitation, electrostatic attraction, and ion exchange. The reusability and practicability in actual wastewater treatment of 3nganese oxide nanomaterials were further discussed. Several key problems still need to be solved in the existing progress, such as improving the ability and stability of the iron­manganese oxide nanomaterials to remove heavy metals from actual wastewater. In conclusion, this review provides a future direction for the application of iron­manganese oxide nanomaterials for heavy metals removal and even in the large-scale treatment of actual wastewater.

Amelioration of Coastal Salt-Affected Soils with Biochar, Acid Modified Biochar and Wood Vinegar: Enhanced Nutrient Availability and Bacterial Community Modulation.

As an important part of the ecological environment, degraded coastal soils urgently require efficient and eco-friendly soil amendment. Biochar and wood vinegar have been proved to be effective soil amendments, and acid-modified biochar has great potential in ameliorating the degraded coastal saline-alkali soil. However, the effects of individual or combined application of biochar (BC), acid-modified biochar (ABC), and wood vinegar (WV) on coastal saline-alkali soil are unknown. Hence, biochar, wood vinegar, and acid-modified biochar were prepared by pyrolysis of poplar wood. The properties of biochar were characterized, and soil incubation experiments were conducted. The results showed that ABC decreased the soil alkalinity by acid-base neutralization and improved the soil fertility by increasing the nutrients (C, N, P). ABC provided a more suitable environment and changed the abundance and diversity of soil microorganisms. ABC increased the relative contents of specific families (e.g., Pseudomonadaceae and Sphingomonadaceae), which had strong ecological linkages in the C, N, and P cycles and organic matter degradation. The results indicated that WV had little effect on coastal saline-alkali soil, whereas individual and combined application of biochar (especially ABC) showed an efficient remediation effect. Our preliminary study demonstrated that the ABC could be a suitable solution for ameliorating degraded coastal saline-alkali soils.

Determining the influencing factors of preferential flow in ground fissures for coal mine dump eco-engineering.

Ground fissures (GF), appearing in front of dumps, are one of the most obvious and harmful geological hazards in coal mining areas. Studying preferential flow and its influencing factors in the ground fissures of dumps may provide basic scientific support for understanding the rapid movement of water and vegetation restoration and reconstruction in mining areas. Based on field surveys of ground fissures, three typical ground fissures were selected in the studied dump. The morphological characteristics of preferential flow for ground fissures were determined through field dye tracing, laboratory experiments, and image processing technology. The results indicated that the lengths of the three ground fissures ranged from 104.84 cm to 120.83 cm, and the widths ranged from 2.86 cm to 9.85 cm. All of the ground fissure area densities were less than 10%, and the proportion of ground fissure surface area was small in the dump. The maximum fissure depth was 47 cm, and the minimum was 16 cm. The ground fissure widths ranged from 0 cm to 14.98 cm, and the fissure width and fissure width-to-depth ratios decreased with increasing soil depth. The stained area was greater than 90% in the 0-5 cm soil layers of the three fissures, and water movement was dominated by matrix flow. The stained width decreased from 90 cm to 20 cm with increasing soil depth. The preferential flow was mainly concentrated on both sides of the fissure, which was distributed as a "T" shape. The preferential flow stained area ratios were 27.23%, 31.97%, and 30.73%, respectively, and these values decreased with increasing soil depth. The maximum stained depths of the preferential flow among the three fissures were different, and the maximum stained depth of GF II was significantly larger than that of GF I and GF III (P < 0.05). The stained path numbers of the three fissures ranged from 0 to 49. With increasing soil depth, the stained path number first increased and then decreased. The stained path widths of the three fissures ranged from 0 cm to 90 cm. With the increase in soil depth, the stained path width decreased. The stained area ratio was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter, and sand content and was significantly negatively correlated with soil water content and clay content. The stained path number was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity and soil organic matter. The stained path width was significantly positively correlated with the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter and sand content and was significantly negatively correlated with clay content. Plant roots could significantly increase the stained area ratio, stained path number, and width and promote the formation and development of preferential flow.

Transport of Amino Acids in Soy Sauce Desalination Process by Electrodialysis.

Soy sauce is a common condiment that has a unique flavor, one that is derived from its rich amino acids and salts. It is known that excessive intake of high-sodium food will affect human health, causing a series of diseases such as hypertension and kidney disease. Therefore, removing sodium from the soy sauce and retaining the amino acids is desirable. In this study, electrodialysis (ED) was employed for the desalination of soy sauce using commercial ion exchange membranes (IEMs). The influence of the current density and initial pH on the desalination degree of the soy sauce was explored. Results showed that the optimal desalination condition for ED was reached at a current density of 5 mA/cm2 and pH of 5, with the desalination degree of 64% and the amino acid loss rate of 29.8%. Moreover, it was found that the loss rate of amino acids was related to the initial concentration and molecular structure. In addition, the amino acid adsorption by IEMs was explored. Results implied that the molecular weight and structure affect amino acid adsorption. This study illustrated that the ED process can successfully reduce the salt content of the soy sauce and retain most of the amino acids without compromising the original flavor.

An ultrasensitive electrochemical DNA sensing strategy free from pre-immobilization via G-quadruplex based homogenous proximity hybridization.

Motivated by the desire for simple, rapid and highly sensitive DNA detection, we presented a signal-on electrochemical DNA (E-DNA) sensing strategy utilizing cooperative proximity hybridization based on a G-quadruplex (G4) probe labeled with the SH, which could specifically hybridize with its target DNA in homogenous solution. In the presence of target DNA, proximity hybridization was triggered to form a Y-shaped complex and the SH was released from G4 probe stem, companied by chemisorption on the electrode surface through Au-S binding when applied a positive potential, which brought Fc labeled on the signal probe close to the electrode surface. Thus, electrochemical signal dramatically increased, ensuring the highly sensitive "signal-on" assay. Such an E-DNA sensing strategy allows for ultrasensitive DNA detection with a detection limit as low as 2.82 × 10-15 M and a wide linear response from 1.0 × 10-9 to 1.0 × 10-15 M. In addition, the powerful discriminating ability of the mismatched DNA from the perfect matched target DNA was also demonstrated. More importantly, this homogenous proximity hybridization strategy could expand to colorimetric assay by incorporating G4 probe with hemin to form DNAzyme, which could effectively catalyze ABTS to generate a visual color change. Taking the joint advantages of G4 stem-loop probe and homogenous proximity hybridization, this sensing strategy exhibits greatly enhanced sensitivity and excellent specificity, making it a promising strategy for point-of-care testing.