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22761. 题目: Natural levels of hydrogen peroxide (H2O2) in deep clear South temperate lakes: Field and laboratory evidence of photo- and biotic production Hydrogen peroxide (H2O2) is a ubiquitous reactive oxygen species (ROS) in aquatic systems and is produced mainly in surface water by the interaction of ultraviolet radiation (UVR) and natural dissolved organic carbon (DOC). Andean Patagonian lakes are ultraoligotrophic, clear systems with extended photic zones (~40 m), and are exposed to challenging UVR levels due to their lati-altitudinal situation and extremely low DOC levels. This investigation describes the seasonal levels of H2O2 in relation to DOC quality in the water column of lakes Moreno East (ME) and Moreno West (MW), two deep (ca. 100 m), ultraoligotrophic, low-DOC (<0.7 mg L−1) systems of Andean Patagonia. H2O2 concentrations recorded in the lakes were below 60 nM, ranging from ~3 to ~60 nM in Lake ME and from ~5 to ~35 nM in Lake MW. In most of the samples of both lakes, the H2O2 levels were higher in the photic zone (surface to 30–40 m) than the aphotic zone (from 30–40 m to 90–100 m), particularly in summer samples. Laboratory experiments evaluated the abiotic (photochemical) and biotic (microbial) production of H2O2 in seasonal (summer, autumn) samples which varied DOM quality due to lake (ME, MW) and depth (photic and aphotic lake layers) provenance. Abiotic and biotic production of H2O2 attained higher levels in summer samples from the photic zones of both lakes. Humic DOM from deep layers (particularly from summer samples) was more susceptible to both photo- and bio-degradation than DOM from upper lake layers, which was characterized by stronger signs of degradation and progress in diagenesis. | |||||
22762. 题目: Variations of dissolved organic matter and Cu fractions in rhizosphere soil induced by the root activities of castor bean The root soil interaction affects metal bioavailability in the rhizosphere, thus impacting the uptake and accumulation of metals by plants. In this study, a greenhouse experiment using a root-bag technique for castor bean plants was conducted to determine the i) rhizosphere effect on the fractions of Cu, and ii) the characteristics of dissolved organic matter (DOM) in the rhizosphere soil. Results showed that the Cu concentration in the leaves, stems, and roots was 15.41, 6.71, and 47.85 mg kg−1, respectively, in the control and reached up to 96.5, 254.9, and 3204 mg kg−1 in Cu400 treatment, respectively. After cultivating castor bean plants, the concentration of acid exchangeable Cu in rhizosphere soil was higher than that in the bulk soil for the same Cu addition, whereas the concentrations of reducible Cu, oxidizable Cu, and residual Cu in the rhizosphere soil were all lower than those in the bulk soil, respectively. In comparison to the bulk soil, the pH decreased while the total nitrogen and total carbon concentrations both increased in the rhizosphere soil. Moreover, the concentrations of total low molecular weight organic acids (LMWOAs) and total amino acids in the rhizosphere soil of the Cu treatments increased by between 15.18% to 47.17% and 36.35%–200%, respectively with respect to the control. The less complex DOM with a high LMWOAs concentration in the rhizosphere soil shifted the soil Cu from a relative stable fraction to available fractions. | |||||
22763. 题目: High-yield and high-performance porous biochar produced from pyrolysis of peanut shell with low-dose ammonium polyphosphate for chloramphenicol adsorption Adsorptive removal by porous carbon materials has been considered an attractive technique to treat wastewater polluted by antibiotics. To produce porous biochar with high-yield and high-performance for chloramphenicol adsorption, this study prepared biochar from peanut shells using ammonium polyphosphate via pyrolysis. The combined effects of the main process parameters on biochar production were studied to determine the optimum operating conditions by response surface methodology based on Box-Behnken design. Low-dose ammonium polyphosphate has a significant positive effect on the yield, surface functional groups, pore volume, and surface area of biochar. This is caused by the richness of nitrogen and phosphorus in ammonium polyphosphate and its flame retardant property. The high-yield biochar with a surface area of 979 ± 25 m2/g was obtained at a mass ratio of ammonium polyphosphate/peanut shell of 0.55, at 650 °C with a retention time of 60 min. The as-prepared biochar exhibited excellent adsorption performance with a monolayer chloramphenicol adsorption capacity of 423.7 mg/g. This was due to the high surface area, micropores formed by nano-sized particles, and richness of N- and P-containing functional groups. The characterization before and after chloramphenicol adsorption indicated micro-pore-filling, Van der Waals force, π-π interaction, and hydrogen-bonding interaction are the main adsorption mechanisms of chloramphenicol adsorption on as-prepared biochar. This study offered new insights on the preparation of biochar from waste biomass for application in wastewater treatment. | |||||
22764. 题目: Highly efficient U(VI) removal by chemically modified hydrochar and pyrochar derived from animal manure In recent decades, great attention has been given to developing methods for targeted modification of biochar with innovative properties to improve its remediation efficacy. This study investigated the sorption performance of animal manure-derived hydrochar and pyrochar modified with oxidizing agents (H2O2) and alkaline (NaOH) solutions for U(VI). Characterization results showed that H2O2 and NaOH modification provided more carboxyl and hydroxyl groups, respectively, on sample surface. NaOH treatment remarkably increased specific surface area by three to six times. H2O2 and NaOH impressively improved the maximum adsorption capacity (Qmax) of biochar for U(VI), and NaOH modification induced a higher enhancement. Among different biochar types, pyrochar produced at a medium-high temperature not only showed the highest Qmax but also the strongest improvement. After NaOH modification, its Qmax (221.4 mg/g) was roughly 5-fold higher than that of original sample, showing that with NaOH modification, the pyrochar produced from animal manure under a medium-high thermal temperature might be a promising candidate as a sorbent for U(VI) remediation. In addition, the obvious shift in the XPS spectrum and pore structure of sample after U(VI) loading, along with the semi-quantification of the contribution of surface complexation mechanism, demonstrated that additional carboxyl and hydroxyl groups and higher SSA jointly explained more efficient U(VI) adsorption. This study not only proposes a promising adsorbent for U(VI) in nuclear wastewater, but also provides a way for the efficient recycling of animal manure wastes. | |||||
22765. 题目: Polybessurus-like fossils as key contributors to Permian–Triassic boundary microbialites in South China Massive occurrences of microbialites near the Permian–Triassic boundary in the Tethyan area have been interpreted as being due to benthic microbial proliferation in unusual marine conditions after the end-Permian mass extinction. Here, we present large populations of Polybessurus-like microfossils in the microbialites of the South China Craton to reveal their morphological structures, growth patterns, and ecological implications. These distinctive microfossils are composed of layered stalks and spherical endpoints. The spheroids, 20–40 μm in diameter, comprising external thin micritic walls and internal sparry parts, are interpreted as coccoid cyanobacteria. The stalks consist of multiple stacked-cup micritic envelopes consisting of micron grade magnesian calcite/dolomite grains and are catalogued as calcified remains of coccoid cyanobacterial extracellular polymeric substances (EPS). Early microbially mediated calcification of EPS increased the preservation potential of microfossils. The microfossils stand upright as coccoid unicells supported by the highly unidirectional secretion of EPS, revealing their benthic behaviours. The successively secreted EPS lift the cells away from the substrate, expanding their ecological niches to gain more sunlight for photosynthesis in the barren marine floor. The distinctive Polybessurus-like microfossils can be viewed in both laminae of stromatolites and spotted/digitate clots of thrombolites, suggesting their critical roles in microbially dominated reefs in the aftermath of the end-Permian mass extinction. The morphological features and growth patterns of the Polybessurus-like fossils resemble their Proterozoic counterpart—Polybessurus bipartitus Fairchild ex Green et al. (1987). The widespread Polybessurus-like fossils in the Permian–Triassic boundary microbialites of the South China Craton suggest pervasive retrogressive ecosystems in the carbonate platform after the largest extinction event in Earth's history. | |||||
22766. 题目: Monitoring inland water quality using remote sensing: potential and limitations of spectral indices, bio-optical simulations, machine learning, and cloud computing Given the recent advances in remote sensing analytics, cloud computing, and machine learning, it is imperative to evaluate capabilities of remote sensing for water quality monitoring in the context of water resources management and decision-making. The objectives of this review were to analyze recent advances in water quality remote sensing and determine limitations of current systems, estimation methods, and suggest future improvements. To that end, we collected over 200 sets of water quality data including blue-green algae phycocyanin (BGA-PC), chlorophyll-a (Chl-a), dissolved oxygen (DO), specific conductivity (SC), fluorescent dissolved organic matter (fDOM), turbidity, and pollution-sediments from 2016 to 2018. The water quality data, generated from laboratory analysis of grab samples and in-situ real-time monitoring sensors distributed in eight lakes and rivers in Midwestern United States, were paired with synchronous proximal spectra, tripod-mounted hyperspectral imagery, and satellite data. The results showed that both proximal and satellite-based sensors have great potential to provide accurate estimate of optically active parameters, and remote sensing of non-optically active parameters may be indirectly estimated but still remains a challenge. Data-driven empirical approaches, i.e., deep learning outperformed the other competing methods, providing promising possibility for operational use of remote sensing in water quality monitoring and decision-making. As the first-time review of deep neural networks for water quality estimation, the paper concludes that anomaly detection utilizing multi-sensor data fusion and virtual constellation in cloud-computing is the most promising means for predicting impending water pollution outbreaks such as algal blooms. | |||||
22767. 题目: Insights into the regulation mechanisms of algal extracellular polymeric substances secretion upon the exposures to anatase and rutile TiO2 nanoparticles As an important part of extracellular secondary metabolites, extracellular polymeric substances (EPS) can play a significant role in protecting cells from the threat of exogenous substances, including nanoparticles (NPs). However, the regulation mechanisms of EPS secretion under NPs exposure remain largely unknown. This study investigated the signaling pathways and molecular responses related to EPS secretion of algae (Chlorella pyrenoidosa) upon the exposures to anatase and rutile TiO2 NPs (nTiO2-A and nTiO2-R, respectively) at two similar toxic (20% and 50% of algal growth inhibition) concentrations. The results showed that EPS responded to nTiO2 stress via excess secretion and compositional variation, and nTiO2-A induced more EPS secretion than nTiO2-R at similar toxicity concentrations. The up-regulation of the Ca2+ signaling pathway might play a greater role in promoting EPS secretion under nTiO2-R exposure compared with nTiO2-A exposure, while the significantly increased intracellular ROS could mainly account for the increased EPS secretion under nTiO2-A exposure. The up-regulated genes related to biological synthesis and protein metabolism and the enhanced biosynthetic metabolism might be the direct causes of the increased EPS secretion. The increased ROS could have a greater effect on the amino acid metabolism and related genes upon the exposure to nTiO2-A than nTiO2-R to induce more EPS secretion. More serious membrane damage caused by nTiO2-R than nTiO2-A would affect the intracellular inositol phospholipid metabolism more severely, while the inositol phospholipid pathway and Ca2+ signaling pathway might agree and communicate with each other inherently to regulate EPS secretion upon nTiO2-R exposure. The findings address the regulation mechanisms of algal EPS secretion under nTiO2 exposure and provide new insights into algal bio-responses to nTiO2 exposure. | |||||
22768. 题目: Influences of tropical monsoon climatology on the delivery and dispersal of organic carbon over the Upper Gulf of Thailand Organic carbon cycling in SE Asia is data-sparse and poorly studied, although high sediment yield and organic carbon intensity occur in the tropical region. In the present study, we evaluated the role of tropical monsoon pertaining to fluvial discharge, sediment load, coastal current and water stratification on seasonal organic carbon dynamics during four sampling campaigns in the Upper Gulf of Thailand (UGoT). This study demonstrates that particulate organic carbon (POC) is closely correlated with the river influx of suspended sediment, which is generally regulated by the local rainfall. Higher POC is found near the large estuarine section (Chao Phraya River, CHAO) during southwest monsoon period and the small estuarine section (Mae Klong River, MK) during November 2013 when tropical cyclones impacted. POC in the estuarine sections is more significantly influenced by the seasonal shift compared with the coastal sections. Land-derived organic matter prevails in the small estuarine and coastal sections, while marine-derived organic matter dominates in the estuarine sections impacted by CHAO and MK. Anthropogenic inputs and dam regulation also influences the river export of organic matter during the high precipitation periods. Total organic carbon (TOC) however displays less significant seasonal monsoon variations than POC. Further, TOC tends to accumulate in the sub-silt fraction of sediments, which mainly occurs in the small estuarine and eastern coastal sections and is more obviously influenced by marine-derived factors. TOC in sediment of the CHAO and MK influenced sections however displays more seasonal variations with prevailing river input evidenced by coarser sediment and higher C/N ratios. Moreover, the almost year round water stratification across the region acts as the barrier in retaining organic carbon in the estuaries and their vicinities from dispersal into the lower portion of Gulf of Thailand. High sedimentation rate (~1.1 cm·yr−1) further facilitates the organic carbon burial in the study area. The delivery, dispersal and burial of organic carbon are closely associated with the climate-controlled precipitation, and thus the tropical monsoon climatology under the global warming in particular is an important factor influencing the organic carbon in the UGoT. | |||||
22769. 题目: High surface area biochar from Sargassum tenerrimum as potential catalyst support for selective phenol hydrogenation Biochar is a biomass-derived carbon-rich, highly porous, and renewable material, which can be used as catalyst support. In this study, high surface area biochar is prepared from Sargassum tenerrimum dry seaweed (SDSW) by the chemical activation method. The effect of variations in experimental conditions (KOH amount, carbonization temperature, activation time, and heating rate) on the physicochemical properties of activated biochar was investigated. Optimum activated carbon (SDSW-ABC) has been used as catalyst support for the preparation of Ni and Co based catalyst. Prepared catalyst (NiCo/SDSW-ABC) was characterized using BET, TGA, XRD, TPD, TPR, and TEM. Catalytic activity of NiCo/SDSW-ABC was evaluated for phenol hydrogenation at a wide range of temperatures (60–140 °C), hydrogen pressures (3–7 MPa), and reaction times (2–8 h) in various polar solvents. The catalyst demonstrated selective phenol conversion (≥99.9%) to cyclohexanol (≥99.9%) at 5 MPa, 100 °C, and 4 h in isopropanol. NiCo/SDW-ABC also explored for hydrogenation of few other lignin model compounds with different functionalities to evaluate the applicability of catalyst. | |||||
22770. 题目: Performance of Cyperus papyrus in constructed wetland mesocosms under different levels of salinity Constructed wetlands (CWs) are consolidated technologies used for removing organic matter (OM) and nutrients (nitrogen (N) and phosphorus (P)) from wastewater. Recently, these systems have been implemented for treating wastewater under saline conditions. In this context, the aim of this study was to evaluate the effect of wastewater with different levels of salinity, expressed as electrical conductivity (EC), on the removal efficiencies of OM and on the growth of vegetation planted in CW mesocosms. For this, five horizontal subsurface flow constructed wetlands (HSSFs) planted with Cyperus papyrus were operated under different salinity levels: 1 (CW-C), 2.5 (CW-2.5), 5 (CW-5), 7.5 (CW-7.5) and 10 mS/cm (CW-10) using CW-C as a control system. To analyze the effects of different salinity levels, the removal efficiencies of chemical oxygen demand (COD) and biological oxygen demand (BOD5) were evaluated. Moreover, the growth characteristics of Cyperus papyrus were compared in the different CWs through the determination of chlorophyll concentration and nutrient contents in different plant tissues. The results of this study showed that the removal efficiencies of OM were above 50%. Regarding the effect of salinity on the removal of contaminants, the COD and BOD5 removals decreased 18% and 31%, respectively, from CW-C to CW-10 (p < .05). The sodium (Na+) concentration in Cyperus papyrus increased 82% when the salinity increased from 1 (CW-C) to 10 mS/cm (CW-10). In contrast, the chlorophyll concentration decreased 17% with increasing salinity (from 1 to 10 mS/cm). Finally, the vegetation presented mechanisms of salt tolerance, mainly Na+ accumulation in plant tissues. Despite these results, the technology of CWs could be a feasible alternative for the treatment of saline wastewater improving the plant selection. | |||||
22771. 题目: Water Browning Controls Adaptation and Associated Trade-Offs in Phytoplankton Stressed by Chemical Pollution | |||||
22772. 题目: Anode potential-dependent protection of electroactive biofilms against metal ion shock via regulating extracellular polymeric substances Extracellular polymeric substances (EPS) have been considered as a barrier for toxic species penetration into the cells, but their function in protecting electroactive biofilms (EABs) had been rarely revealed. In this study, the anode potential was used to regulate the EPS quantity and components in mixed-culture EABs, where their resistance to Ag+ shock was assessed. The results showed that the EAB grown at 0 V showed the highest anti-shock capability by the Ag+ exposure compared to those grown at −0.2, 0.2, and 0.4 V. The EAB produced at 0 V had both of the highest amounts of loosely bound EPS (LB-EPS; 61.9 mg-EPS/g-VSS) and tightly bound EPS (TB-EPS; 74.8 mg-EPS/g-VSS) than those grown under other potentials, where proteins and humic acid were the predominated components. The abundance of genes associated with EPS biosynthesis were also confirmed to be related with the applied anode potentials, based on the metagenomic analysis. Considering proteins and humic acid in LB-EPS showed positive linearity with the current recovery and viability of the EABs, these two main components might play important roles in reducing the Ag+ toxicity. Synchronous fourier transform infrared (FTIR) spectroscopy integrated two-dimensional correlation spectroscopy (2D-COS) analyses further confirmed that the oxygen and nitrogen moieties (i.e. amide, carbonyl CO, phenolic, and C–O–C) in proteins of the LB-EPS were response for the binding with the Ag+ to prevent the penetration into the cells. The underlying molecular mechanisms of EPS in protecting EABs from the Ag+ shock explored in this study can provide implications for developing new methods to construct highly stable EABs. | |||||
22773. 题目: Is the operationally defined fraction of soil organic matter, GRSP (glomalin‐related soil protein), stable in soils? Evidence from trends in long‐term bare fallow soil The operationally defined fraction of soil organic matter (SOM), glomalin‐related soil protein (GRSP) has been reported to be particularly stable. This is the first study to test this hypothesis. Archived soil has been used from the long‐term bare fallow trial, known as the 42‐Plots, in Versailles, France. With no input from plants for 80 years, changes in GRSP must result from either turn‐over of SOM or net mineralization. Intrinsically stability of protein would lead to progressive enrichment in GRSP. Soils from treatments that influenced pH, soil C:N ratio and physical stability were studied. Soil having received manure amendment was also studied to give contrasting microbial activity. Both GRSP and soil organic carbon (SOC) contents declined over the 80‐year period, with the exception of the manure‐treatment. GRSP and SOC contents were positively correlated. SOC was continuously enriched in GRSP in the Control treatment, suggesting greater stability of GRSP. The SOC in manure‐amended soil was also progressively enriched in GRSP, but this can be attributed to the GRSP content of added manure. For the other treatments the ratio GRSP:SOC fell continuously (CaCO3‐amendment) or fell to a minimum value after 45 years (KCl‐amendment) or levelled off after a progressive increase ((NH4)2SO4‐amendment). Trends are compared with measured soil properties, and changes in microbial activity inferred from soil pH. No reliable independent assessment of microbial composition of these archived soils is possible. The results cannot be explained by inherent chemical or physico‐chemical stability of GRSP. We conclude that recycling of SOM continually produces soil protein. The net change in GRSP content is a complex function of SOM cycling and protein mineralization. These findings add to the increasing body of evidence that the operationally defined fraction of SOM known as GRSP does not predominantly originate from arbuscular mycorrhizal fungal activity. | |||||
22774. 题目: Alluvial landform and the occurrence of paleosols in a humid-subtropical climate have an effect on long-term soil organic carbon storage Soil organic carbon (SOC) storage in alluvial depositional zones is important as it serves as a centennial to millennial timescale sink of C. This study examines SOC variability in alluvial bars, floodplains and terraces in a forested, humid-subtropical setting along the Clarks River in the Mississippi River basin (MRB) using replicated soil sampling, characterization and modeling. Soil and depositional profiles range in age from a minimum of 8000 years ago to modern. Normalized (by depth) mean SOC stocks (kg m−2) of the surface soil and buried layers, i.e., buried soils and layers underlying lithologic discontinuities, are highest in the terraces. Normalized mean surface SOC stocks decrease from terraces to floodplains and then to bars; whereas normalized mean buried layer SOC stocks decrease from terraces to bars, and then floodplains. The depth distribution of stocks showed that buried layers accounted for >50% of the total SOC pool, regardless of landform type. A regression tree analysis shows that soil horizon, pH, landform, and magnetic susceptibility were significant predictors of mean SOC content. Notably, the regression tree shows that alkaline pH (>7.9), observed only in buried layers in the terrace, is an important predictor in higher mean SOC. These alkaline soil pH values were associated with paleosol calcite, where the δ13C and 14C from the calcite suggests it formed under C3 vegetation during the drier than modern mid-Holocene hypsithermal, ~8000 years ago. Buried soil and sediment contain the majority of the SOC in this humid-subtropical valley bottom, while landform position and past buried soil-forming environments (paleosols) played an important role in the storage of that SOC. This work reconfirms that there is a long record of a passive, buried SOC pool found deep in our river valley bottoms that holds clues to the past biogeochemical cycling of C on land prior to intensive agriculture and industrialization. The legacy of past Holocene climates and paleosols are directly linked to our current understanding of long-term storage of SOC. | |||||
22775. 题目: Preferential degradation of leaf- vs. root-derived organic carbon in earthworm-affected soil Earthworms are integral parts of many ecosystems and may play a decisive role in determining whether soils function as carbon (C) sink or source. However, information on how earthworms affect the composition and stability of soil organic matter (SOM) is scarce. Particularly their effect on organic matter deriving from leaves and roots with distinct composition and, thus, susceptibility to decomposition and stabilization remains unclear. Here, we combine cutin- and suberin-derived lipids as specific markers for leaf- and root-derived SOM with their 13C composition and physical fractionations of soil. We show that earthworms overprint the protective role of organo-mineral associations and aggregates to favor the accumulation of root- relative to leaf-derived SOM. This gradual accumulation contributes to the often-observed dominance of root-derived organic matter in soil and emphasizes the need to consider molecular level effects of earthworms on SOM dynamics. | |||||
22776. 题目: Differential effects of redox conditions on the decomposition of litter and soil organic matter | |||||
22777. 题目: Enhanced Immobilization and Phytoremediation of Heavy Metals in Landfill Contaminated Soils | |||||
22778. 题目: Insights into facile synthesized pomelo biochar adsorbing thallium: potential remediation in agricultural soils | |||||
22779. 题目: Residual acidified biochar modulates growth, physiological responses, and water relations of maize ( Zea mays ) under heavy metal–contaminated irrigation water | |||||
22780. 题目: Uptake of organic nitrogen by coastal wetland plants under elevated CO 2 | |||||
