Three surveys were carried out to study the phytoplankton role in influencing the Hg distribution in a poorly eutrophic estuary by measuring the total Hg (THg) and methylHg (MeHg) concentrations in ...waters and four-size fractions of phytoplankton. The THg and MeHg concentrations in waters and phytoplankton varied markedly temporal during the three surveys. The total concentrations of THg and MeHg in the four-size fractions of phytoplankton ranged between 0.62 and 28.15 mg/kg and 0.022–4.411 mg/kg, respectively. The dominance of THg and MeHg phytoplankton concentrations differed from different size fractions and varied with the various surveys. The huge uptake of Hg by abundant phytoplankton decreased both Hg concentrations in waters and phytoplankton, which was attributed to the biomass dilution effect during the July survey. The Hg partition between water and phytoplankton provided substantial evidence to illustrate the huge uptake of Hg by the abundant phytoplankton.
•The total Hg and MeHg concentrations in phytoplankton of the estuary were mg/kg level.•The Hg partition reflects huge uptake of dissolved Hg by phytoplankton.•The Hg and MeHg concentrations in phytoplankton varied with different size fractions.•The BCF values of Hg and MeHg of phytoplankton in the estuary exceed 105 and 104.
Due to its large specific surface area and great hydrophobicity, microplastics can adsorb polycyclic aromatic hydrocarbons (PAHs), affecting the bioavailability and the toxicity of PAHs to plants. ...This study aimed to evaluate the effects of D550 and D250 (with diameters of 550 μm and 250 μm) microplastics on phenanthrene (PHE) removal from soil and PHE accumulation in maize (Zea mays L.). Moreover, the effects of microplastics on rhizosphere microbial community of maize grown in PHE-contaminated soil would also be determined. The results showed that D550 and D250 microplastics decreased the removal of PHE from soil by 6.5% and 2.7% and significantly reduced the accumulation of PHE in maize leaves by 64.9% and 88.5%. Interestingly, D550 microplastics promoted the growth of maize and enhanced the activities of soil protease and alkaline phosphatase, while D250 microplastics significantly inhibited the growth of maize and decreased the activities of soil invertase, alkaline phosphatase and catalase, in comparison with PHE treatment. In addition, microplastics changed the rhizosphere soil microbial community and reduced the relative abundance of PAHs degrading bacteria (Pseudomonas, Massilia, Proteobacteria), which might further inhibit the removal of PHE from soil. This study provided a new perspective for evaluating the role of microplastics on the bioavailability of PHE to plants and revealing the combined toxicity of microplastics and PHE to soil microcosm and plant growth.
Arsenic (As) is a persistent toxic substance, however, its toxicity to marine zooplankton remains unclear. In this study, copepods were exposed to a series of dissolved arsenate (As(V)) for four ...generations (F0–F3) and subsequently depurated in clean seawater for two generations (F4–F5) to assess multigenerational toxicity of As(V). As(V) exposure prolonged copepod development. The development time were 1.9, 2.4, and 3.4 days longer than the control in F0 when exposed to 50, 100, and 500 μg/L As(V), respectively, and the toxicity increased with generations. Moreover, As(V) reduced the reproductive capacity of copepods, and this effect become more severe during generation succession. The 10-day fecundities were reduced from 80 to 85 eggs per female in the control to 42 eggs per female, the lowest level, in 500 μg/L As(V) exposure group in F3. Nevertheless, the fecundity was recovered to the control level in the offspring of the 50 and 100 μg/L As(V) exposed groups (F4), suggesting it was an acclimation effect of copepods during As(V) exposure. In addition, the survival rate, development time, and reproductive parameters were significantly correlated with the As accumulation in copepods. Overall, As(V) exposure caused As bioaccumulation which negatively affected copepods' survival, development, and reproductive traits, and this toxic effect was amplified with generations and concentrations. Therefore, the multigenerational toxicity of As should be considered in the environmental risk assessments.
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•Multigenerational As(V) exposure had negative effects on copepod survival, developmental time, and number of offspring.•As(V) bioaccumulation is responsible for the variations in survival rate, development time, and 10-day fecundity.•The development time and 10-day fecundity of the exposed offspring were restored in the As(V)-free generation.
•Evictions in Cairo reflect a shift to neoliberal authoritarianism since 2014.•This shift prioritizes the state’s urban accumulation and economically benefits it.•The evictions also (re)produce ...surplus labor, to the state’s economic benefit.•Politically, the evictions depoliticize central Cairo and discipline its population.•While power relations favor the state, they are not static and are contested.
Cr0.09V2O5(H2O)2·H2O (CrVO) curly nanosheets and CoVO porous microflowers were synthesized. Rietveld refinement unveils CrVO consists of V-O-V layers, lamellar {Cr(H2O)6}3+ cations and dissociated ...water, in which all the V centers are unsaturated coordinated. As a result, the V-O-V bilayer in V2O5 is split into two discrete V-O-V monolayers in CrVO with the (001) facet as the division plane and the interlayer spacing is large up to 14.5 Å. The exposed V centers on the (001) surface are unsaturated with oxygen vacancies, which can facilitate the migration of Zn2+ along the surface with a lower energy barrier of 0.68 eV, as evidenced by DFT calculations. CrVO shows a dominant surface-controlled capacity, which can deliver a large capacity of 497 mAh g−1 at 0.1 A g−1 with excellent long-term durability. The capacity retention is 96 % after 1000 discharge/charge cycles at 5 A g−1, which is superior to the isostructural CoVO. Ex situ characterizations of CrVO indicate a co–(de)intercalation mechanism of H+/Zn2+, and DFT calculations reveal that the intercalation of Zn2+ on some sites in the inner channel of CrVO is partial irreversible with very negative binding energies, leading to the accumulation of Zn2+ in CrVO. However, the transformation of CrVO → Znx(CrVO) doesn’t change the lattice spacing of (001) facet obviously, and Znx(CrVO) can be maintained after cycling test.
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•CrVO exhibits excellent Zn2+ storage behavior.•CrVO consists of V-O-V layers, lamellar {Cr(H2O)6}3+ and dissociated water.•All the V centers in CrVO are unsaturated coordinated.•DFT simulation confirms a low Zn2+ migration barrier along CrVO (001) surface.•The insertion of Zn2+ on some sites in CrVO is irreversible with unchanged d spacing.
Cr0.09V2O5(H2O)2·H2O (CrVO) curly nanosheets and CoVO porous microflowers were synthesized. Rietveld refinement unveils CrVO consists of V-O-V layers, lamellar {Cr(H2O)6}3+ cations and dissociated water, in which all the V centers are unsaturated coordinated. As a result, the V-O-V bilayer in V2O5 is split into two discrete V-O-V monolayers in CrVO with the (001) facet as the division plane and the interlayer spacing is large up to 14.5 Å. The exposed V centers on the (001) surface are unsaturated with oxygen vacancies, which can facilitate the migration of Zn2+ along the surface with a lower energy barrier of 0.68 eV, as evidenced by DFT calculations. CrVO shows a dominant surface-controlled capacity, which can deliver a large capacity of 497 mAh g−1 at 0.1 A g−1 with excellent long-term durability. The capacity retention is 96 % after 1000 discharge/charge cycles at 5 A g−1, which is superior to the isostructural CoVO. Ex situ characterizations of CrVO indicate a co–(de)intercalation mechanism of H+/Zn2+, and DFT calculations reveal that the intercalation of Zn2+ on some sites in the inner channel of CrVO is partial irreversible with very negative binding energies, leading to the accumulation of Zn2+ in CrVO. However, the transformation of CrVO → Znx(CrVO) doesn’t change the lattice spacing of (001) facet obviously, and Znx(CrVO) can be maintained after cycling test.
Investigating the particle deposition mechanism on the solar PV module surfaces is beneficial to predict the dust accumulation amount and formulate the dust cleaning scheme. This study ...comprehensively analyzed the particles mechanical behavior in the movement and collision process with the module surfaces. Then, the energy-based particle deposition criterion was proposed and a dust accumulation numerical model under the experiment condition was established. Comparing the simulation and experimental results verified the rationality of particle deposition criterion and simulation method. Based on this, the effects of wind speed, humidity, and particle size on the dust accumulation characteristics of PV modules were simulated. Moreover, the dust accumulation impact on PV performance was predicted. The results showed the dust accumulation amount presents a greater effect on PV transmittance than efficiency. Furthermore, the dust accumulation decreases first and then increases with increasing wind speed, and the minimum occurs at 3 m/s, approximately 1.45 g/m2. However, the dust accumulation increases approximately linear with increasing humidity. Additionally, the dust accumulation amount displays a negative correlation with particle size under 30% humidity, and when particle size increases from 10 μm to 30 μm, the dust accumulation decrease from 9.76 g/m2 to 2.59 g/m2 at 1 m/s, resulting in the reduction of PV efficiency reduces from 14.64% to 3.89% and the transmittance reduction decreases from 25.32% to 8.38%. In future research, developing a specific self-cleaning coating to prevent the deposition of 10 μm particles is conducive to improve the PV efficiency and transmittance while reducing the dust accumulation.
•The particle deposition criterion based on energy was proposed.•A dust accumulation experiment was performed to verify the simulation rationality.•Wind speed, humidity, and particle size impact on dust accumulation were simulated.•Dust accumulation impact on PV module efficiency and transmittance was predicted.
Arsenic, cadmium, lead, and mercury are toxic elements that are almost ubiquitously present at low levels in the environment because of anthropogenic influences. Dietary intake of plant-derived food ...represents a major fraction of potentially health-threatening human exposure, especially to arsenic and cadmium. In the interest of better food safety, it is important to reduce toxic element accumulation in crops. A molecular understanding of the pathways responsible for this accumulation can enable the development of crop varieties with strongly reduced concentrations of toxic elements in their edible parts. Such understanding is rapidly progressing for arsenic and cadmium but is in its infancy for lead and mercury. Basic discoveries have been made in
Arabidopsis
, rice, and other models, and most advances in crops have been made in rice. Proteins mediating the uptake of arsenic and cadmium have been identified, and the speciation and biotransformations of arsenic are now understood. Factors controlling the efficiency of root-to-shoot translocation and the partitioning of toxic elements through the rice node have also been identified.
The accumulation of NO3− in the soil has resulted in increased nitrogen (N) loss through runoff, leaching, and gaseous emissions. Microbial immobilization of NO3− as an important process in reducing ...soil NO3− accumulation has been for a long time neglected due to the predominant viewpoint that microbes preferentially immobilize NH4+-N. Microbial NO3− immobilization is generally carbon (C)-limited, and thus exogenous organic C input may enhance microbial NO3− immobilization. However, the effect of the quality and quantity of exogenous organic C input on soil microbial NO3− immobilization is poorly understood, and a synthetic assessment on such an effect is lacking. We thus assessed the impact of exogenous organic C type, the application rate of simple organic C (glucose and acetate), complex organic C type (animal manure, plant residue) and the C/N ratio of complex organic C on soil microbial NO3− immobilization rate using a meta-analysis. We found that the quality and quantity of exogenous C input affect soil microbial NO3− immobilization: microbial NO3− immobilization was enhanced with the addition of simple organic C at rates >500 mg C kg−1, or complex organic C with C/N ratios >18. Furthermore, a positive relationship between the natural log of response ratio of soil microbial NO3− and NH4+ immobilization indicates the simultaneous utilization of NH4+ and NO3− under elevated C availability. We conclude that specific exogenous organic C input at a high rate or with a high C/N ratio can enhance microbial NO3− immobilization and reduce soil NO3− accumulation.
•Effects of simple and complex C on microbial NO3− immobilization were different.•NO3− immobilization was enhanced with simple C addition at rates >500 mg C kg−1.•NO3− immobilization was enhanced with complex C addition of C/N ratios >18.•It is possible to add exogenous C to increase soil microbial NO3− immobilization.
A demonstration crystallization reactor and struvite accumulation device for the removal and recovery of phosphorous was constructed and their performance was evaluated using actual swine wastewater ...for 3.5 years. The wastewater pH was increased by aeration, and the concentrations of total P and soluble PO sub(4)-P were reduced by a struvite crystallization reaction induced under a high pH condition. A 30% MgCl sub(2) addition was effective in enhancing the struvite crystallization reaction. The concentrations of suspended solids, total Zn and total Cu, were also decreased by the settling function of the reactor. On removing the efficiencies of these components, no noticeable seasonal fluctuation in performance was observed during the 3.5-year operation. In terms of maximum yield, 171 g struvite was obtained from 1 m super(3) swine wastewater by the demonstration accumulation device for struvite recovery. The recovered struvite needed only air-drying before use since it was approximately 95% pure even without washing.
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