Achieving ultralow levels of phosphorus (P) concentrations to prevent eutrophication is an important goal of surface water management. Hence, a highly efficient and economical adsorbent for phosphate ...removal is urgently required to meet the increasingly stringent water quality standards. This study investigated the phosphate adsorption performance of zirconium (Zr)-modified calcium-montmorillonite (Zr-CaMs). Batch experiments were conducted to obtain the adsorption isotherms, kinetics, and the influences of dosage, solution pH, and coexisting anions. The results demonstrated that Zr was successfully introduced to the surface and interlayer of raw CaM in the presence of the SiO…HOZr hydrogen bond and that it increased the specific surface area. The adsorption isotherms obeyed the Langmuir nonlinear model. The calculated maximum phosphate adsorption capacity was 22.37 mg/g, which was more than twice that of Phoslock. The Elovich model fit the kinetics data well, which was indicative of chemical adsorption. An optimum dosage of 100/1–150/1 and wide pH range (4–8.5) are recommended for practical applications. The coexistence of HCO3− slightly inhibited the adsorption capacity, whereas Cl− and SO42− had a positive impact. The adsorption mechanism was primarily the ligand exchange between the surface hydroxyl groups and phosphate resulting from the formation of inner-sphere coordination complexes. This study demonstrated that Zr-CaMs can serve as a prospective adsorbent for phosphate removal from contaminated surface water.
•Zr-CaMs were synthesized to remove phosphate from aqueous solution.•Adsorption data followed Langmuir isotherm and Elovich kinetic models.•The maximum phosphate adsorption capacity reached 22.37 mg/g.•Adsorption mechanism was primarily the formation of inner-sphere complexes.•Zr-CaMs can serve as a promising adsorbent for P removal from polluted water.
Formation of thick, high energy density, flexible solid supercapacitors is challenging because of difficulties infilling gel electrolytes into porous electrodes. Incomplete infilling results in a low ...capacitance and poor mechanical properties. Here we report a bottom-up infilling method to overcome these challenges. Electrodes up to 500 μm thick, formed from multi-walled carbon nanotubes and a composite of poly(3,4-ethylenedioxythiophene), polystyrene sulfonate and multi-walled carbon nanotubes are successfully infilled with a polyvinyl alcohol/phosphoric acid gel electrolyte. The exceptional mechanical properties of the multi-walled carbon nanotube-based electrode enable it to be rolled into a radius of curvature as small as 0.5 mm without cracking and retain 95% of its initial capacitance after 5000 bending cycles. The areal capacitance of our 500 μm thick poly(3,4-ethylenedioxythiophene), polystyrene sulfonate, multi-walled carbon nanotube-based flexible solid supercapacitor is 2662 mF cm
at 2 mV s
, at least five times greater than current flexible supercapacitors.
Human activities have greatly altered terrestrial carbon (C) dynamics associated with vegetation cover and land use changes, thereby influencing the C sink in downstream ecosystems. However, the ...transport and preservation of organic C from soils that experience serious erosion in the karst area are scarce, particularly at catchment scales. In this study, chemical characteristics of organic matter (OM) isolated from the topsoil, overlying water, and lake sediments, as well as subsequent source identification, were inferred from the molecular, spectroscopic, and carbon isotopic (δ
13
C) signatures in a typical karst catchment, Southwestern China. The results indicated that the elemental compositions of the calcareous soil and paddy soil significantly differed from the yellow soil. High similarities existed in the fluorescence spectra of humic substances (HS) extracted from the front two soil types with those of lake sediments, indicating the homogeneous nature of OM molecular structure. The C/N ratios of six dissolved OM fractions and sedimentary HS along with δ
13
C values consistently reflected the primary terrestrial source. It was estimated to account for 60% of total organic C in sedimentary OM by end-member mixing modeling in accordance with soil erosion intensity and large recharge coefficient of this catchment. The evolution of soil loss and lake productivity can be well deduced from sediment records of organic C content, C/N ratio, and the specific information of HS. This research highlighted that the composition, source, and fate of OM in the karst lake was mainly dominated by the terrestrial C flux, rather than in-lake production. Furthermore, soil type and erosion intensity have significant effects on the nature of eroded OM and ultimate preservation.
The purpose of this study was to investigate the distribution pattern, pollution status and potential ecological risk of Cr, Co, Ni, Cu, As, Cd, Sb, and Pb in soils and dominant plants around an ...abandoned red mud (RM) slag yard in Southwestern China. Soils exhibited representative enrichment and combination characteristics of these metals compared to the background values, ascribed to the leaching of long-term acid rain on the RM dump. The soil was moderately to severely polluted with As and Sb. Cd also posed a moderate ecological risk. Asteraceae species predominated in the RM slag yard, followed by
Coriaria sinica
and
Robinia pseudoacacia
. No plants were identified as hyperaccumulators because of low bioconcentration values, whereas
Cosmos bipinnata
can act as a potential phytostabilizer of heavy metals based on the translocation factor. The results provided effective decision support for reducing heavy metal pollution by phytoremediation RM stacking fields.
As sensors, wireless communication devices, personal health monitoring systems, and autonomous microelectromechanical systems (MEMS) become distributed and smaller, there is an increasing demand for ...miniaturized integrated power sources. Although thin-film batteries are well-suited for on-chip integration, their energy and power per unit area are limited. Three-dimensional electrode designs have potential to offer much greater power and energy per unit area; however, efforts to date to realize 3D microbatteries have led to prototypes with solid electrodes (and therefore low power) or mesostructured electrodes not compatible with manufacturing or on-chip integration. Here, we demonstrate an on-chip compatible method to fabricate high energy density (6.5 μWh cm ⁻²⋅μm ⁻¹) 3D mesostructured Li-ion microbatteries based on LiMnO ₂ cathodes, and NiSn anodes that possess supercapacitor-like power (3,600 μW cm ⁻²⋅μm ⁻¹ peak). The mesostructured electrodes are fabricated by combining 3D holographic lithography with conventional photolithography, enabling deterministic control of both the internal electrode mesostructure and the spatial distribution of the electrodes on the substrate. The resultant full cells exhibit impressive performances, for example a conventional light-emitting diode (LED) is driven with a 500-μA peak current (600-C discharge) from a 10-μm-thick microbattery with an area of 4 mm ² for 200 cycles with only 12% capacity fade. A combined experimental and modeling study where the structural parameters of the battery are modulated illustrates the unique design flexibility enabled by 3D holographic lithography and provides guidance for optimization for a given application.
Significance Microscale batteries can deliver energy at the actual point of energy usage, providing capabilities for miniaturizing electronic devices and enhancing their performance. Here, we demonstrate a high-performance microbattery suitable for large-scale on-chip integration with both microelectromechanical and complementary metal-oxide–semiconductor (CMOS) devices. Enabled by a 3D holographic patterning technique, the battery possesses well-defined, periodically mesostructured porous electrodes. Such battery architectures offer both high energy and high power, and the 3D holographic patterning technique offers exceptional control of the electrode’s structural parameters, enabling customized energy and power for specific applications.
Urban aquatic ecosystems in plains are often subject to extensive anthropogenic pollutant inputs and have prolonged times for pollutant degradation, potentially leading to diverse carbon emission ...patterns. This study explored carbon emission patterns and underlying mechanisms in Ge Lake and its tributaries, located in an urban area within a plain in China. The results revealed that carbon emissions from rivers were significantly higher than those from the downstream lake. Spatial interpolation analysis further revealed that CO2‐eq emissions from a 1‐km2 river area can be equivalent to those from an area as large as 86‐km2 of the downstream lake. Rivers are the gateway for the entry of organic compounds, often carrying substances that are readily biodegradable. As the river water moves slowly, these compounds accumulate and undergo degradation in rivers before they reach downstream lakes. The findings may benefit the estimates of carbon emissions in these regions with greater precision.
Plain Language Summary
Carbon dioxide (CO2) and methane (CH4) are the two most important greenhouse gases. Inland waters are hotspots of CO2 and CH4 emissions, greatly contributing to atmospheric levels. This study investigated the patterns of CO2 and CH4 emissions from aquatic ecosystems within plains, known for high pollutant loads and extended residence times. The results revealed that CO2 and CH4 emissions from rivers were significantly higher than those from the downstream receiving lake, exhibiting a decrease along the river flow direction. Rivers serve as the gateway for the entry of pollutants to aquatic environments, often carrying substances that are readily biodegradable. As the river water moves slowly, these compounds accumulate and undergo degradation in rivers before they reach downstream lakes, and therefore, CO2 and CH4 emissions diminish in the downstream direction. The findings add the understanding of carbon emissions in plain aquatic ecosystems, and benefit their estimates in these regions with greater precision.
Key Points
Carbon emissions from urban rivers were higher than the downstream receiving lake
Carbon emissions exhibited a decreasing trend along the river flow direction
Urban rivers warrant more attention in regional estimates of carbon emissions
Microbial beta diversity has been recently studied along the water depth in aquatic ecosystems, however its turnover and nestedness components remain elusive especially for multiple taxonomic groups. ...Based on the beta diversity partitioning developed by Baselga and Local Contributions to Beta Diversity (LCBD) partitioning by Legendre, we examined the water-depth variations in beta diversity components of bacteria, archaea and fungi in surface sediments of Hulun Lake, a semi-arid lake in northern China, and further explored the relative importance of environmental drivers underlying their patterns. We found that the relative abundances of
Proteobacteria
,
Chloroflexi
,
Euryarchaeota
, and
Rozellomycota
increased toward deep water, while
Acidobacteria
,
Parvarchaeota
, and
Chytridiomycota
decreased. For bacteria and archaea, there were significant (
p
< 0.05) decreasing water-depth patterns for LCBD and LCBD
Repl
(i.e., species replacement), while increasing patterns for total beta diversity and turnover, implying that total beta diversity and LCBD were dominated by species turnover or LCBD
Repl
. Further, bacteria showed a strong correlation with archaea regarding LCBD, total beta diversity and turnover. Such parallel patterns among bacteria and archaea were underpinned by similar ecological processes like environmental selection. Total beta diversity and turnover were largely affected by sediment total nitrogen, while LCBD and LCBD
Repl
were mainly constrained by water NO
2
−
-N and NO
3
−
-N. For fungal community variation, no significant patterns were observed, which may be due to different drivers like water nitrogen or phosphorus. Taken together, our findings provide compelling evidences for disentangling the underlying mechanisms of community variation in multiple aquatic microbial taxonomic groups.
Accurate measurement of the oxygen isotopic composition of dissolved phosphate (δ18OP) of different phosphorus (P) fractions in lacustrine sediments is very difficult because of the influence of ...large amounts of impurities. In this study, we developed a five-step method for obtaining high purity Ag3PO4 sample for the analysis of δ18OP of different P fractions in freshwater sediments. Sedimentary P was divided into NaHCO3-P, NaOH-P and HCl-P by chemical sequential extraction. Pretreatment procedures for different sedimentary P fractions were improved in the following respects: 1) abandonment of the magnesium-induced coprecipitation method to avoid the introduction of impurity ions, such as Mg2+ and Cl−, and reduce the loss of P; 2) use of a small amount of non-phosphate activated carbon powder to efficiently remove organic matter in extracts of NaHCO3-P and NaOH-P, and reduce the loss of P; 3) adjustment of the HCl-P extract pH to 4 in order to form Fe(OH)3-PO43− coprecipitate, thereby removing most of metals and Cl−. This method reduces the pretreatment steps, simplifies the operation and increases the recovery of phosphate (90.98%–96.69%). The high purity Ag3PO4 sample can be obtained and the repeatability and accuracy of measured δ18OP is better than 0.3‰, demonstrating high reliability and accuracy. This new method was used to analyze the δ18OP of different P fractions in sediments of a eutrophic lake in southwestern China. The preliminary results indicated that the δ18OP in the sediments can be used to identify different P sources, and provide new insights into sedimentary P cycling. The method established in this study provides a powerful tool for investigating the sources and biogeochemical cycle of P in freshwater sediments.
Display omitted
•A five-step method for the analysis of δ18OP of different P fractions in freshwater sediments was established.•Use of non-phosphate activated carbon powder can remove organic matter in NaHCO3-P and NaOH-P extracts more easily.•Coprecipitation of Fe(OH)3-PO43- can remove most of metals and Cl- in HCl extract efficiently at the beginning.•We provide a powerful tool for investigating the sources and biogeochemical cycle of P in freshwater sediments.
Directed energy deposition (DED) is an important approach to fabricate metallic functionally gradient materials (FGMs). During DED process, two kinds of metallic powder are blown into molten pool ...with gradually changing powder feed rates to achieve material gradients in FGM. DED process always causes poor surface roughness and limited dimensional accuracy, which have to be overcome by machining. Different mechanical properties of two powder materials generate heterogeneous mechanical properties in FGM, which seriously influence cutting mechanism, such as cutting temperature, surface roughness, and tool wear, especially if one material is a hard-to-cut material. However, so far, there has not been any research particularly focused on this problem. This work investigated hybrid manufacturing FGMs involving DED and machining. SS316L and IN718 were fabricated into FGM specimen with DED process. Then, a tungsten carbide (WC) milling cutter machined the FGM specimen under dry peripheral milling condition. A series of material tests were performed to characterize the material properties of FGM specimen. Additionally, surface roughness, machining temperature observations, and tool wear were studied to investigate machining mechanism. Based on the experimental results, it is found that the cutting temperature close to IN718 region was higher than the cutting temperature close to the SS316L region. After machining, the surface colors of IN718 and SS316L regions were bright blue and bright silver, respectively. The surface roughness of SS316L region was greater than that in the IN718 region. In FGM (from 100% SS316L to 100% IN718) after machining, the machined surface colors were shown as yellow, bright yellow, and purple, with the surface roughness found decreasing gradually. Since IN718 is a typical hard-to-cut material, milling cutter is also observed to have obvious wear close to IN718 side. This work firstly studied the fabrication of FGM part with hybrid manufacturing (DED and machining) and provided valuable experimental data of machining the SS316/In718 FGM.
The chloride ion (Cl−) is a type of anion which is commonly found in the environment and has important physiological functions and industrial uses. However, a high content of Cl− in water will do ...harm to the ecological environment, human health and industrial production. It is of great significance to strictly monitor the Cl− content in water. Following the recent development of society and industry, large amounts of domestic sewage and industrial sewage are discharged into the environment, which results in the water becoming seriously polluted by Cl−. The detection of Cl− has gradually become a research focus. This paper introduces the harm of Cl− pollution in the environment and summarizes various Cl− detection methods, including the volumetric method, spectrophotometry method, electrochemical method, ion chromatography, paper-based microfluidic technology, fluorescent molecular probe, and flow injection. The principle and application of each technology are described; their advantages, disadvantages, and applicability are discussed. To goal of this research is to find a more simple, rapid, environmental protection and strong anti-interference detection technology of Cl−.
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