Abstract
Diabetes has become a universal epidemic in recent years. Herein, the monitoring of glucose in blood is of importance in clinical applications. In this work, PtNi alloy nanoparticles ...homogeneously dispersed on graphene (PtNi alloy-graphene) was synthesized as a highly effective electrode material for glucose detection. Based on the modified PtNi alloy-graphene/glass carbon (PtNi alloy-graphene/GC) electrode, it is found that the PtNi alloy-graphene/GC electrode exhibited excellent electrocatalytic performance on glucose oxidation. Furthermore, the results from amperometric current–time curve show a good linear range of 0.5–15 mM with the limit of detection of 16 uM (S/N = 3) and a high sensitivity of 24.03 uAmM
−1
cm
−2
. On account of the good selectivity and durability, the modified electrode was successfully applied on glucose detection in blood serum samples.
Using samples collected in Shahe Reservoir in the upper North Canal in China, this research analyzes the structure of a microorganism group in sediment and the absolute abundance of two typical ...pathogenic bacteria (Escherichia coli and Enterococcus), and their relationship with environmental factors including total nitrogen (TN) and total phosphorus (TP). The study of samples collected from the surface (0-20 cm) and sediment cores shows that the absolute abundance of E. coli in horizontal distribution in the sediment is highest in downstream of the reservoir and point source pollution area. In vertical distribution, the absolute gene expression level of the two pathogenic bacteria in the sediment tends to decrease with increasing depth, although its highest value at 10-30 cm depth. The relative abundance the two pathogenic bacteria is much greater in the sediment of Shahe Reservoir with the structure of horizontal groups including Clortridium sensu stricto, unclassified Anaeroineaceae, and Povalibacter, while Anaeroineaceae is much more abundant in the group structure of the vertical distribution. Pearson correlation analysis suggests positive correlation in horizontal distribution for E. coli and TN and TP (P < 0.05) and for Enterococcus and TP (P < 0.05). The results clearly show that the amount of pathogenic bacteria in the sediment in Shahe Reservoir is most likely due to water eutrophication.
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•Unveil interactions between the C, N and P stoichiometry existed in the dominant plant-soil system.•Dominant plants adapt soil As contamination by allocating more nutrients to leaves ...to ensure photosynthesis and growth.•Plants with P-fixing ability or less P demand may appear with succession proceeding.
The ecological environment in mining area is fragile, and the carbon (C), nitrogen (N), and phosphorus (P) content of dominant plants is closely related to plant nutrient limitation, community composition and ecosystem function. Clarifying the response of dominant plants to soil properties and the corresponding trade-off mechanism are essential for rebuilding the ecological resilience and self-sustaining ability of mining areas. In order to explore the response of dominant plant element traits to soil physico-chemical properties under the stress of soil arsenic (As) pollution, an abandoned metal mining area threatened by heavy soil As pollution was selected as the research area, the soil physico-chemical properties and soil As content in different speciation, and the contents of C, N and P in dominant plants were measured. The results showed that: (1) The soil As pollution was serious in the mining area, while the contents of soil nutrient were relatively low. (2) The soil As content in different speciation affected the absorption and utilization of P by plants. (3) The dominant plants responded to soil As toxicity by allocating more nutrients to leaves to reduce toxicity and ensure growth. This study helps to reveal the nutrient driving law of plant diversity processes and community succession in heavy metal-contaminated sites and is of great significance to restore the fragile ecosystems in mining areas.
Abstract
Shahe Reservoir of Northern Canal Basin was selected as the study area. Nineteen surface (0~20 cm) sediment samples and three sediment core samples were collected to analyze the spatial ...distribution characteristics of As, Cd, Cu, Mn, Pb and Zn in the sediments. The geo-accumulation index, potential ecological risk index and risk assessment code were used to evaluate heavy metal pollution, as well as its potential risk was analyzed according to the speciation of heavy metals. Results showed that the average enrichment factors of heavy metals compared to the background value in soil of Beijing were ranked at the order as the point source pollution area > the central area of the reservoir > the downstream area of the reservoir > the Nansha River > the upstream area of the reservoir > the Beisha River, namely, 2.57 times, 2.06 times, 1.97 times, 1.95 times, 1.87 times and 1.85 times, respectively. The sediment core samples in the central area of the reservoir and the inlet of the Beisha River showed a trend of increasing firstly and then decreasing with the change of depth. Pollution assessment results showed that sediment was moderately contaminated or moderately to strongly contaminated by As, but the other heavy metals were not polluted or lightly polluted. The potential ecological risk index of all sampling sites was less than 150, showing a low ecological risk. As Cr and Cu were mainly in the speciation of residues, with low bioavailability. Although the content of Mn and Zn were low, they showed high bioavailability. Based on correlation analysis and principal component analysis, it was speculated that the sources of various heavy metal pollution in the sediment were similar, which were possibly input from the external wastewater. The heavy metals in sediment were positively related to nutrients and organic matter, indicating that all of them were mostly from the same point polluted sources.
Activated carbon can be applied to the treatment of wastewater loading with different types of pollutants. In this paper, a kind of activated carbon in granular form (GAC) was utilized to eliminate ...antibiotics from an aqueous solution, in which Tetracycline (TC), Thiamphenicol (THI), and Sulfamethoxazole (SMZ) were selected as the testing pollutants. The specific surface area, total pore volume, and micropore volume of GAC were 1059.011 m
/g, 0.625 cm
/g, and 0.488 cm
/g, respectively. The sorption capacity of GAC towards TC, THI, and SMZ was evaluated based on the adsorption kinetics and isotherm. It was found that the pseudo-second-order kinetic model described the sorption of TC, THI, and SMZ on GAC better than the pseudo-first-order kinetic model. According to the Langmuir isotherm model, the maximum adsorption capacity of GAC towards TC, THI, and SMZ was calculated to be 17.02, 30.40, and 26.77 mg/g, respectively. Thermodynamic parameters of Δ
, Δ
, and Δ
were obtained, indicating that all the sorptions were spontaneous and exothermic in nature. These results provided a knowledge base on using activated carbon to remove TC, THI, and SMZ from water.
Ground-penetrating radar (GPR) is an efficient and nondestructive geophysical method with great potential for detecting soil water content at the farmland scale. However, a key challenge in soil ...detection is obtaining soil water content rapidly and in real-time. In recent years, deep learning methods have become more widespread in the earth sciences, making it possible to use them for soil water content inversion from GPR data. In this paper, we propose a neural network framework GPRSW based on deep learning of GPR data. GPRSW is an end-to-end network that directly inverts volumetric soil water content (VSWC) through single-channel GPR data. Synthetic experiments show that GPRSW accurately identifies different VSWC boundaries in the model in time depth. The predicted VSWC and model fit well within 40 ns, with a maximum error after 40 ns of less than 0.10 cm3 × cm−3. To validate our method, we conducted GPR measurements at the experimental field of the Academy of Agricultural Sciences in Gongzhuling City, Jilin Province and applied GPRSW to VSWC measurements. The results show that predicted values of GPRSW match with field soil samples and are consistent with the overall trend of the TDR soil probe samples, with a maximum difference not exceeding 0.03 cm3 × cm−3. Therefore, our study shows that GPRSW has the potential to be applied to obtain soil water content from GPR data on farmland.
Soil-heavy metal pollution in mining areas is one of the problems in the comprehensive treatment of soil environmental pollution. To explore the degree of soil-heavy metal pollution and the human ...health risk in mining areas, the contents of soil As, Cd, Cu, Cr, Hg, Ni, Pb, and Cr(VI) in an abandoned gold mining area were determined. The geoaccumulation index (Igeo), single-factor pollution index (SPI), Nemerow comprehensive pollution index (NCPI), potential ecological risk index (PERI), and the human health risk assessment model were used to assess the pollution degree and the risk of soil-heavy metal pollution. Finally, the assessment results were used to provide remediation guidance. The results showed that (1) the average contents of As, Cd, Cr, Cu, Hg, and Ni in the mining area exceeded the background values of the soil elements. (2) The mining area was polluted by heavy metals to different degrees and had strong potential ecological hazards. (3) The total carcinogenic risk of heavy metals exceeded the health risk standard. The main components of pollution in the mining area were As, Cd, Cr, and Hg. Results from this study are expected to play a positive role in pollution treatment and the balance between humans and ecology.
Ground-penetrating radar (GPR) is an important tool for measuring soil water content (SWC) at the field scale. The amplitude analysis of the early time signal (ETS) of GPR may provide a rapid way to ...estimate SWC. By assuming a homogeneous medium, various studies have been conducted on the relationship between the amplitude of ETS and the topsoil layer’s electromagnetic parameters (dielectric permittivity and conductivity) through numerical simulations, laboratory experiments, and field experiments. Soil is a typical inhomogeneous medium, and soil cultivation is a factor affecting its heterogeneity. In this context, we discuss the ability of the amplitude of ETS to estimate the water content of heterogeneous soil. First, we establish a multi-scale stochastic medium model with the inhomogeneous distribution of dielectric permittivity and conductivity and simulate the GPR response by the finite-difference time-domain (FDTD) method to observe the influence of medium heterogeneity on the GPR response. The heterogeneity of the soil models is evaluated by a geostatistical analysis described by two parameters, correlation length and variability. Then, we analyze the relationship between variability and the average envelope amplitude (AEA) of ETS. A strong soil heterogeneity increases the error of the AEA method in estimating SWC. Finally, the AEA method is used to estimate the SWC of two adjacent fields with different heterogeneities, which were caused by different cultivation methods. The results of the numerical simulation and field experiment indicate that the soil heterogeneity can have an impact on the estimation of SWC using EST, with an error lower than 3% within a depth range of 1/2 λ to λ (wavelength). This suggests that the EST of GPR can be applied to soil layers with relatively large lateral changes in water content.
In order to explore a medium material for the efficient treatment of Pb(II) pollutants in groundwater, in this paper, mudstone is selected as the medium material, and the morphological structure of ...the mudstone is characterizes via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analyses to study the feasibility of the mudstone adsorbing Pb(II) ions. Then, static adsorption experiments are carried out to investigate the removal effect of mudstone on Pb(II) in aqueous solutions under different conditions and to determine the optimal adsorption conditions. Finally, the results are fitted and analyzed using a thermodynamic model to explore the adsorption mechanism of the mudstone. The main results of this study are as follows. The main mineral composition of the mudstone used in the experiments includes CaCO3, SiO2, CaAl2O4·10H2O, and CaFe4O7. The specific surface area of the mudstone is as high as 23.027 m2·g−1, the pore size is 9.145 nm, and its surface structure is rough, with pores and fissures developed. The pore space and adsorption capacity of the mudstone were enhanced. When 1 g·L−1 of mudstone was added, the pH value of the solution was 6, the reaction time was 60 min, and the initial concentration of Pb(II) was 30 mg·L−1. The removal efficiency of Pb reached 84.5%, and the adsorption amount was 25.352 mg·g−1. For the removal of Pb(II) from the aqueous solution by the mudstone under different concentrations of Pb(II), the reaction was in accordance with the Langmuir adsorption isotherm model, and the maximum adsorption amount reached 54.975 mg·g−1. The relationship between the removal of Pb(II) and the reaction time was in accordance with the pseudo-second-order rate model. The results of this study suggest that mudstone can be used for the removal of Pb(II) from aqueous media.
The Loess Plateau is an important region for soil and water conservation and ecological construction in China. Exploring the spatio-temporal variations in soil conservation and water conservation ...services and their relationships in Loess Plateau under the background of land consolidation projects is of great significance for ecological protection and quality development in the Yellow River Basin. Taking Yan’an city as the research area, this paper used the InVEST model to quantitatively evaluated spatio-temporal variation characteristics and trade-off/synergy relationship of the soil conservation and water conservation services from 2010 to 2018. According to the implementation data, the relationship between the gully control and land consolidation (GCLC) project in various counties of Yan’an city and soil conservation and water conservation service was analyzed. The results showed that the total amount of soil conservation services in Yan’an City were 4.07 × 10 6 t and 3.75 × 10 6 t in 2010 and 2018 with a decrease of 7.76%, and with low spatial clustering characteristic. The total amount of water conservation services were 2.01 × 10 10 mm and 2.03 × 10 10 mm in 2010 and 2018 with a increase of 0.56%, and with high spatial clustering characteristic. There is a synergistic relationship between soil conservation and water conservation services in most area of Yan’an city. From 2010 to 2018, the effect of the GCLC projects on soil conservation and water conservation services in Yan’an city is not significant. The GCLC project can effectively alleviate the situation of sharp decline of cultivated land area and insufficient food production capacity.
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