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1. 题目: Soil phosphorus dynamics along a short‐term ecological restoration trajectory of a coastal sandplain forest in New Zealand
文章编号: N20092902
期刊: Land Degradation and Development
作者: Hongtao Zhong, Carol Smith, Brett Robinson, Young‐Nam Kim, Nicholas Dickinson
更新时间: 2020-09-29
摘要: We aim to understand the impact of ecological restoration on soil biogeochemistry, and the interrelationship between vegetation and soil phosphorus. In a study of two different‐aged soils in coastal New Zealand, soils are described along a transition from abandoned agricultural pasture, through 6‐year old restoration plots, towards forest fragments that have been largely undisturbed for 75 and 166 years. Soil biogeochemistry varied spatially along this restoration trajectory; there were profound changes in surface soil, but little impact on deeper soil horizons. In the early stages, soil organic matter accumulation and decomposition, and increasing demand of N from fast‐growing plants corresponded with rapid nutrient mineralization. Loss of soil total P, an increase of occluded P, and the increasing importance of soil organic P as soils weathered and aged, supported conceptual models of longer‐term soil pedogenesis. There was no evidence that the success of the establishment of plants varied across the site, but this is a first report of vegetation establishment during ecological restoration markedly impacting soil P dynamics and biogeochemistry.

2. 题目: Organic matter from the Chicxulub crater exacerbated the K–Pg impact winter
文章编号: N20092901
期刊: Proceedings of the National Academy of Sciences
作者: Shelby L. Lyons, Allison T. Karp, Timothy J. Bralower, Kliti Grice, Bettina Schaefer, Sean P. S. Gulick, Joanna V. Morgan, Katherine H. Freeman
更新时间: 2020-09-29
摘要: An asteroid impact in the Yucatán Peninsula set off a sequence of events that led to the Cretaceous–Paleogene (K–Pg) mass extinction of 76% species, including the nonavian dinosaurs. The impact hit a carbonate platform and released sulfate aerosols and dust into Earth’s upper atmosphere, which cooled and darkened the planet—a scenario known as an impact winter. Organic burn markers are observed in K–Pg boundary records globally, but their source is debated. If some were derived from sedimentary carbon, and not solely wildfires, it implies soot from the target rock also contributed to the impact winter. Characteristics of polycyclic aromatic hydrocarbons (PAHs) in the Chicxulub crater sediments and at two deep ocean sites indicate a fossil carbon source that experienced rapid heating, consistent with organic matter ejected during the formation of the crater. Furthermore, PAH size distributions proximal and distal to the crater indicate the ejected carbon was dispersed globally by atmospheric processes. Molecular and charcoal evidence indicates wildfires were also present but more delayed and protracted and likely played a less acute role in biotic extinctions than previously suggested. Based on stratigraphy near the crater, between 7.5 × 10 14 and 2.5 × 10 15 g of black carbon was released from the target and ejected into the atmosphere, where it circulated the globe within a few hours. This carbon, together with sulfate aerosols and dust, initiated an impact winter and global darkening that curtailed photosynthesis and is widely considered to have caused the K–Pg mass extinction.

3. 题目: Decoupled diversity patterns in microbial geographic distributions on the arid area (the Loess Plateau)
文章编号: N20092802
期刊: Catena
作者: Quanchao Zeng, Dong Liu, Shaoshan An
更新时间: 2020-09-28
摘要:

Soil microbes are essential to biogeochemical cycling, soil organic matter decomposition and climate regulation in terrestrial ecosystems. The biogeography of soil bacteria and fungi lags behind in animals and plants, especially in arid areas with alkaline conditions. Understanding the biogeographic of soil microbes and the interactions with environmental factors will provide new insights into the ecosystem functions and services droved by soil bacteria and fungi. Therefore, we chose 48 dryland sites from two transects (north-south and east-west transects) on the Loess Plateau (an arid area) to determine soil bacterial and fungal diversity and community compositions in response to environmental factors and geographic distance. The results showed that soil organic carbon enhanced soil fungal diversity rather than soil bacterial diversity, while soil bacterial diversity was not affected by the environmental factors on the Loess Plateau. The significant associations between the abundance of main bacteria and fungi and soil pH, suggesting that soil pH was the predominant factor affecting soil microbial community structure. In the alkaline soils (pH = 7.4–9.1), soil bacterial community compositions were limited by soil pH, while soil fungal community composition was less sensitive in response to the alterations in soil pH, revealing soil fungi has a wider optimal pH range than bacteria. Compered to historical contingencies, local environment mainly controlled the geography of bacteria and fungi in soils. On the Loess Plateau, soil microbial communities diverge most by soil pH, especially for soil bacteria. These results provide a well understanding of soil microbial geography and associated biogeochemical cycling in arid areas with higher soil pH.

4. 题目: Adsorption of microplastic-derived organic matter onto minerals
文章编号: N20092801
期刊: Water Research
作者: Yun Kyung Lee, Jin Hur
更新时间: 2020-09-28
摘要:

Microplastic (MP) pollution is an increasing global problem due to the ubiquity of these particles in the environment and the uncertainty surrounding their fate. Most MPs undergo extensive weathering in the environment, which may result in the release of dissolved organic matter (DOM) into the aqueous phase. In this study, for the first time, we examined the adsorptive behavior of MP-derived DOM (MP-DOM) on minerals (kaolinite and goethite) using DOM samples leached from commercial plastics including polyvinylchloride (PVC) and polystyrene (PS) under dark and ultraviolet (UV) irradiation conditions. MP-DOM was characterized by a higher distribution of relatively smaller-sized molecules than natural organic matter (NOM). The PS-derived DOM (PS-DOM) leached under UV treatment exhibited more oxygen-containing groups than their counterparts in the dark. MP-DOM also exhibited net negative charges at neutral pH ranges. Adsorption isotherm experiments revealed that the mineral surfaces had high adsorption affinities for both types of MP-DOM, which is likely associated with both electrostatic attraction and ligand exchange. The extent of adsorption was greater for the UV-irradiated than the dark-treated DOM, and on goethite compared to kaolinite. The Fourier-transform infrared (FTIR) spectra of the residual PS-DOM after adsorption revealed differences in the adsorption affinities between its functional groups. Two-dimensional correlation spectroscopy for the irradiated PS-DOM showed that preferential adsorption occurred on minerals in the sequential order of oxidized structures → (PS monomers) → carboxylates in additives → carbonyl groups. The adsorption isotherm model parameters for MP-DOM were comparable to those obtained from aquatic/terrestrial NOM, which suggests that plastic-derived DOM can interact with minerals as strongly as NOM. This study highlights the overlooked role played by plastic-derived DOM in mineral-enriched environments, opening new opportunities for improving our understanding of the fate and environmental impacts of MPs.

5. 题目: Application of quorum sensing inhibitors for improving anti-biofouling of polyamide reverse osmosis membranes: Direct injection versus surface modification
文章编号: N20092703
期刊: Separation and Purification Technology
作者: Jaehyeok Kim, MinGyu Shin, WonJung Song, SangHee Park, Junhee Ryu, Jaehyun Jung, SuYoung Choi, Youngjae Yu, Jihyang Kweon, Jung-Hyun Lee
更新时间: 2020-09-27
摘要:

Quorum sensing inhibitors (QSIs) have shown promising results in reducing biofouling in various membrane systems. Vanillin was shown to inhibit QS of gram-negative bacteria during water treatment. Here, four vanillin-analogues with various chemical structures were used to understand the QS mechanisms in biofilm reduction and to compare direct dosing and surface modification of the inhibitors. Biofilm reduction, evaluated based on the content of extracellular polymeric substances (EPS), was the greatest with vanillin (49%) and occurred to some extent with 4-hydroxybenzaldehyde (21%) and m-anisaldehyde (13%), when direct dosing was applied. Experiments using vanillin-analogues revealed crucial roles of the chemical structure and functional groups on the inhibition of biofilm formation. The aldehyde and hydroxyl groups in both vanillin and 4-hydroxybenzaldehyde might be essential for QS inhibition. Further, surface modification with interfacial polymerization and immobilization of QSIs was conducted to evaluate their anti-biofouling capabilities. Surface modification was markedly effective in reducing biofilm formation; the EPS content of biofilms formed on vanillin-incorporated membranes was reduced by 64%. Additionally, the modified membranes showed a water flux comparable to that of pristine membranes, showing little possibility to block membrane pores during modification procedures. These findings will aid the development of QSI-based techniques for biofouling mitigation.

6. 题目: Terpenoids in surface soils from different ecosystems on the Tibetan Plateau
文章编号: N20092702
期刊: Organic Geochemistry
作者: Yan Bai, Qinghu Chen, Youping Zhou, Xiaomin Fang, Xiaoming Liu
更新时间: 2020-09-27
摘要:

Realizing the potential of terpenoid biomarkers as an unequivocal land ecosystem and floral diversity indicator calls for work to establish a direct link between the terpenoids extracted from the plants and those found in the underlying soils. To this end, we have characterized the triterpenoid profile of soils and vegetation along two altitudinal transects representing very different ecosystems. The first transect, comprising 31 sample sites, was on the eastern slopes of Mt Gongga (eastern Tibetan Plateau) rising from 1230 m to 4500 m above sea level, an area with a temperate monsoonal climate. The second transect, sampling 29 sites, was on the northern slopes of Mt West Kunlun, a region characterized by montane desert, meadow and alpine steppe (located between 1300 m to 5050 m above sea level). The dominant terpenoid biomarkers (polycyclic triterpenoids of the taraxerane, oleanane, friedelane, ursane, lupane, glutinane and lanostane series) identified in the soils were found to be consistent with the overlying vegetation. However, the discovery of some unusual triterpenoids, including the pentacyclic triterpene 3-methyl ethers (PTMEs), D:A-friedo-2,3-secoolean-2,3-dioic acid, methyl 3β-acetoxylup-20(29)-en-28-oate, 24-methylenecycloartan-3-one, 9,19-cyclolanostan-3-yl 24-methylene acetate, 3α-methoxy-9β-lanosta-7,24-dien-26,23-olide and 3α-methoxy-9β-lanost-7-en-26,23-olide in the Gongga soils, does not match the current vegetation and may be indicative of a long vanished forest-type vegetation. Thus, soil biomarkers may be a useful tool in the reconstruction of palaeo-vegetation.

7. 题目: Dissolved oxygen consumption in a fjord-like estuary, Macquarie Harbour, Tasmania
文章编号: N20092701
期刊: Estuarine, Coastal and Shelf Science
作者: Johnathan D. Maxey, Neil D. Hartstein, Amy Yee Hui Then, Matt Barrenger
更新时间: 2020-09-27
摘要:

Microbial respiration of organic matter (OM) is a key driver of deoxygenation and hypoxia. In fjord-like estuaries with established aquaculture industries understanding drivers of oxygen demand, and the relative importance of different drivers, is crucial for improving fish farming management in those systems. We designed a study to examine patterns of pelagic oxygen demand (POD) in a fjord-like estuary on the west coast of Tasmania, Macquarie Harbour, and relate those observations to physical forcings and major OM sources. Monthly water column sampling and bottle incubation experiments were conducted from June to November 2017. Water was collected throughout the harbour including river and oceanic endmembers as well as transects leading away from fish farms. Water was incubated from 4 different depths spanning the surface water to the seabed. Regression modelling was used to examine the relationship between POD, riverine OM loading, proximity to fish farms and the major system endmembers, depth, harbour region, concentration of dissolved oxygen, and month. POD reached rates as high as 0.108 mg L−1 hour−1 with the greatest POD observed above the halocline and during high river flow/OM loading months. Regression modelling showed that important drivers of POD are spatially specific along vertical and longitudinal gradients. The importance of riverine OM loading waned with depth primarily due to mixing dynamics of dissolved organic carbon across the halocline. Proximity to fish farms was an important but localized explanatory variable for POD in the halocline and basin waters, but not a significant driver of POD compared to the Gordon River. Based on the POD rates observed in this study, hypoxia can be established in less than 9 days in the basin waters and is primarily driven by pelagic oxygen sinks (95%–98%), not sediment sinks. It is crucial that aquaculture management accounts for natural, and/or preexisting, variation in endmember OM loading and its effect on DO dynamics, in these systems.

8. 题目: Response of Activated Sludge to Long-Term Nanosilver Input and Changes in Extracellular Polymeric Substances (EPS)
文章编号: N20092613
期刊: Water, Air, and Soil Pollution
作者: Ferhan Çeçen, Ayse Gul Geyik, Başak Kılıç
更新时间: 2020-09-26
摘要: This study investigates the response of activated sludge to continuous nanosilver (AgNPs) input in a large concentration range. In addition to substrate removal, changes taking place in the different fractions of Extracellular Polymeric Substances (EPS), namely, very loosely bound-EPS (VLB-EPS), loosely bound-EPS (LB-EPS), and tightly bound-EPS (TB-EPS), as well as the protein and carbohydrate content of each fraction were examined. At relatively low AgNP concentrations (5 mg/L), production of loosely bound fractions became higher. At AgNP ≥ 12 mg/L, also TB-EPS production was promoted. Seemingly, bacteria were protected from inhibitory effects by regulation of EPS production. Moreover, new proteins emerged in EPS. Respiration tests indicated no effect on substrate removal even at high AgNP concentrations because the nanomaterial lost its effectiveness upon continuous aeration. In WWTPs, AgNP concentrations are normally below 0.8 mg/L. Therefore, no negative impact on substrate removal and no visible changes in EPS production would be expected.

9. 题目: Photolysis of Trenbolone Acetate Metabolites in the Presence of Nucleophiles: Evidence for Metastable Photoaddition Products and Reversible Associations with Dissolved Organic Matter
文章编号: N20092612
期刊: Environmental Science & Technology
作者: Nicholas C. Pflug, Andrew K. Kral, Madeline K. Hankard, Kathryn C. Breuckman, Edward P. Kolodziej, James B. Gloer, Kristine H. Wammer, David M. Cwiertny
更新时间: 2020-09-26
摘要: Photolysis of trenbolone acetate (TBA) metabolites in the presence of various nitrogen-, sulfur-, or oxygen-containing nucleophiles (e.g., azide, ammonia, or thiosulfate, respectively) results in rapid (half-lives ∼20–60 min), photochemically induced nucleophile incorporation across the parent steroid's trienone moiety. The formation of such nucleophile adducts limits formation of photohydrates, suggesting competition between the nucleophile and water for photochemical addition into the activated steroid structure. Analogous to previously reported photohydration outcomes, LC/MS analyses suggest that such photonucleophilic addition reactions are reversible, with more rapid elimination rates than thermal dehydration of photohydrates, and regenerate parent steroid structures. Beyond photonucleophilic addition pathways, we also found that hydroxylamine and presumed nucleophilic moieties in model dissolved organic matter (DOM; Fluka humic acid) can react via thermal substitution with TBA metabolite photohydrates, although this reaction with model DOM was only observed for photohydrates of trendione. Most nucleophile addition products [i.e., formed via (photo)reaction with thiosulfate, hydroxylamine, and ammonia] are notably more polar relative to the parent metabolite and photohydration products. Thus, if present, both nucleophilic adducts and bound residues in organic matter will facilitate transport and help mask detection of TBA metabolites in surface waters and treatment systems.

10. 题目: Polybrominated diphenyl ethers and organochloride pesticides in the organic matter of air suspended particles in Mexico valley: A diagnostic to evaluate public policies
文章编号: N20092611
期刊: Environmental Pollution
作者: E. Beristain-Montiel, R. Villalobos-Pietrini, A. Nuñez-Vilchis, G.E. Arias-Loaiza, I.Y. Hernández-Paniagua, O. Amador-Muñoz
更新时间: 2020-09-26
摘要:

The presence of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was analysed in air particulate matter ≤ 2.5 μm (PM2.5) and ≤10 μm (PM10) collected in the Metropolitan Zone of Mexico Valley (MZMV), during 2013 and 2014, respectively. Spatial and seasonal distributions of PM and their organic content named solvent extracted organic matter (SEOM) were determined. PM mass concentration and SEOM/PM ratios were compared with previous studies in 2006 in Mexico City. PM2.5 concentration was like found in 2006, however, PM10 decreased ∼43%. The SEOM/PM10 ratio was kept constant, suggesting a decrease in SEOM as well as PM10 emitted from natural sources, probably as a result of changes in the land use due to urban growth. A decrease ∼50% SEOM/PM2.5 ratio was observed in the same period, linked to adequate strategies and public policies applied by the local and federal governments to control the organic matter emitted from anthropogenic sources.

Seven out of sixteen OCPs and five out of six PBDEs were found. The most common POPs were endosulfan I, endosulfan II, endosulfan sulfate, BDE-47 and BDE-99, present on >90% of the sampling days. OCPs in PM2.5 and PBDEs in PM10 showed seasonal variability. Higher PBDEs concentration in both particle sizes were observed at east and southeast of the MZMV, where one of the biggest landfills and wastewater treatment plants are located. OCPs in PM10 were mainly emitted from agricultural areas located to the southwest, southeast and east of the MZMV. OCPs in PM2.5 showed a regional contribution from the north and introduced into the valley. OCP degradation products were dominant over native OCPs, indicating no fresh OCP use. POPs comparison with other cities was made. Agreements and commissions created by the Mexican government reduced OCPs emissions, however, more effort must be made to control PBDE emission sources.

11. 题目: Chemical speciation and distribution of potentially toxic elements in soilless cultivation of cucumber with sewage sludge biochar addition
文章编号: N20092610
期刊: Environmental Research
作者: Shengyu Xie, Guangwei Yu, Jianli Ma, Gang Wang, Qichuan Wang, Futian You, Jie Li, Yin Wang, Chunxing Li
更新时间: 2020-09-26
摘要:

Potentially toxic elements in municipal sewage sludge can be effectively immobilized during biochar production via pyrolysis. However, the bioavailability of these elements when biochar is applied in soilless cultivation to improve substrate quality has yet to be sufficiently established. In this study, we investigated the chemical speciation and cucumber plant uptake of potentially toxic elements in soilless cultivation when the growth substrate was amended with sewage sludge biochar (0, 5, 10, 15, and 20 wt%). It was found that the addition of 10 wt% biochar was optimal with respect to obtaining a high cucumber biomass and achieving low environmental risk considering the occurrence of hormesis. When the substrate was amended with 10 wt% biochar, cucumber fruit contained lower concentrations of As, Cr, and Zn and smaller bioavailable fractions of As, Cd, Cr, Ni, Cu, and Zn compared with the fruit of control plants, thereby meeting national safety requirements (standard GB 2762–2012, China). Most of the As and Cd taken up by cucumbers accumulated in the leaves and fruit, whereas Cr was found primarily in the roots, and most Ni, Cu, and Zn was detected in the fruit. Importantly, only small proportions of the potentially toxic elements in biochar were taken up by cucumber plants (As: 0.0075%; Cd: 0.038%; Ni: 0.0064%; Cu: 0.0016%; and Zn: 0.0015%). Given that the As, Cd, Ni, and Zn speciation in sewage sludge biochar was effectively immobilized after cultivation, the findings of this study indicate that sewage sludge biochar is a suitable substrate amendment in terms of the risk posed by potentially toxic elements.

12. 题目: Fencing facility affects plant species and soil organic carbon in temperate steppes
文章编号: N20092609
期刊: Catena
作者: Zhi-Ping Wang, Shi-Jie Han, Yan-Hai Zheng, Xi-Mei Zhang, Hong-Hui Wu, Ji-Fa Cui, Chun-Wang Xiao, Xing-Guo Han
更新时间: 2020-09-26
摘要:

Fencing facility has been widely employed in steppes. However, the effects of fencing facility on plant species and soil organic carbon (SOC) have been rarely understood in steppes. Using soil sampling and plant quadrat clipping methods, in this study, we investigated the effects of fencing facility on the distributions of plant species and SOC in the temperate steppes of the Inner Mongolia. Plant biomass significantly increased with approaching fencing facility and was obviously higher in the leeward (south) than windward (north) sides. Perennial grasses accounted for approximately 68%–76% of the total aboveground biomass in both sides of fencing facility. SOC content also significantly increased with approaching fencing facility in the 0–10 soil layer but slightly increased in the 10–30 cm soil layer. Wind erosion and dust storm did markedly neither change the fractions of soil texture nor cause the difference in SOC content between the windward and leeward sides. Fencing facility increased SOC storage by 16.5% and 9.1% at 0.1 and 0.5 m locations relative to at 3 m location in the 0–10 cm soil layer, respectively. Edge effect is suggested as a potential mechanism driving the variations of plant species and SOC in both sides of fencing facility.

13. 题目: Mobilization of soil inorganic phosphorus and stimulation of crop phosphorus uptake and growth induced by Ceriporia lacerata HG2011
文章编号: N20092608
期刊: Geoderma
作者: Jie Yin, Zong-ming Sui, Jian-guo Huang
更新时间: 2020-09-26
摘要:

The high-quality phosphorus (P) rocks on Earth may be depleted within the next fifty years. Hence, it is important to search for microbes that are effective in mobilizing soil legacy P. Therefore, a novel fungal strain (Ceriporia lacerata HG2011) was isolated and identified based on morphology and molecular biology. Then, liquid culture, soil incubation and field experiments were conducted to investigate the influence of this fungus on P mobilization and crop growth and P uptake in an eggplant-sweet sorghum rotation system. In the liquid culture experiment, P dissolved from Ca3(PO4)2 by fungal proton efflux accounted at least for 86.35% of the total dissolved P and the remainder was released by organic acids. As C. lacerata HG2011 grew on the soil surface, water-soluble P and Olsen P increased as the soil pH decreased. Fungal inoculation increased soil water-soluble P by 13.79–28.85 % and Olsen P by 4.12–17.82% compared to the uninoculated treatment. Compared to the use of chemical fertilizers alone, the field application of fungal inoculant in combination with chemical fertilizers at the time of eggplant transplantation increased crop P uptake by 10.03–29.48%, eggplant fruit yield by 6.83–16.07% and sweet sorghum shoot biomass by 12.59–18.42%. Olsen P and enzyme activities, including those of phosphatase, protease, urease and cellulase, were also significantly increased, probably indicating the stimulation of organic mineralization, releasing available P. To our knowledge, this is the first work providing information on soil P mobilization by C. lacerata, and on the potential use of this fungus as a biofertilizer in sustainable agriculture.

14. 题目: Long‐term active restoration of extremely degraded alpine grassland accelerated turnover and increased stability of soil carbon
文章编号: N20092607
期刊: Global Change Biology
作者: Yanfu Bai, Lina Ma, A. Allan Degen, Muhammad Khalid Rafiq, Yakov Kuzyakov, Jinxue Zhao, Rui Zhang, Tao Zhang, Wenyin Wang, Xiaogang Li, Ruijun Long, Zhanhuan Shang
更新时间: 2020-09-26
摘要:

Soil nutrient contents and organic carbon (C) stability are key indicators for restoration of degraded grassland. However, the effects of long‐term active restoration of extremely degraded grassland on soil parameters have been equivocal. The aims of this study were to evaluate the impact of active restoration of degraded alpine grassland on: 1) soil organic matter (SOM) mineralization; and 2) the importance of biotic factors for temperature sensitivity (Q10) of SOM mineralization. Soils were sampled from intact, degraded and restored alpine grasslands at altitudes ranging between 3900 and 4200 m on the Tibetan Plateau. The samples were incubated at 5 ℃, 15 ℃ and 25 ℃, and Q10 values of SOM mineralization were determined. Structure equation modeling was used to evaluate the importance of vegetation, soil physico‐chemical properties and microbial parameters for Q10 regulation. The Q10 of N mineralization was similar among intact, degraded and restored soils (0.84 ‐ 1.24) and was higher in topsoil (1.09) than in subsoil (0.92). The best predictive factor of CO2‐Q10 for intact grassland was microbial biomass, for degraded grassland was basal microbial respiration, and for restored grassland was soil bulk density. Restoration by planting vegetation decreased the Q10 of SOM mineralization as soil bulk density, the most important negative predictor, increased in restored grassland. The Q10 of SOM mineralization in topsoil was 14% higher than in subsoil because of higher microbial abundance and exo‐enzyme activities. The NH4+ content was greatest in intact soil, while NO3 content was greatest in degraded soil. The SOM mineralization rate decreased with grassland degradation and increased after long‐term (>10 years) restoration. In conclusion, extremely degraded grassland needs proper long‐term management in active restoration projects, especially for improvement of soil nutrients in a harsh environment.

15. 题目: Magnetite-contained biochar derived from fenton sludge modulated electron transfer of microorganisms in anaerobic digestion
文章编号: N20092606
期刊: Journal of Hazardous Materials
作者: Mingwei Wang, Zhiqiang Zhao, Yaobin Zhang
更新时间: 2020-09-26
摘要:

Biochar, with redox moieties or conjugated π-bond, can act as electron shuttle or conductor to facilitate electron transfer of syntrophic metabolism to enhance anaerobic digestion. High pyrolysis temperature (>500 ℃) is usually required to prepare conductive biochar, which however may cause biochar to loss redox moieties such as quinone/hydroquinone that are capable of serving as electron shuttle. Considering that magnetite is an excellent conductor which has been applied in improving syntrophic metabolism of anaerobic digestion, a novel magnetite-contained biochar was prepared using iron-rich Fenton sludge as raw material in this study. Amorphous iron oxides of Fenton sludge were transformed into magnetite at 400 ℃ of pyrolysis, while redox quinone/hydroquinone moieties of biochar were preserved well. Correspondingly, this magnetic biochar owned both high capacitance and excellent conductivity. When supplementing the biochar into an anaerobic digestion system, methane production was significantly enhanced. This study also offered a new approach to recycle Fenton sludge that is regarded as hazardous material.

16. 题目: Soil degradation index developed by multitemporal remote sensing images, climate variables, terrain and soil atributes
文章编号: N20092605
期刊: Journal of Environmental Management
作者: Claudia Maria Nascimento, Wanderson de Sousa Mendes, Nélida Elizabet Quiñonez Silvero, Raúl Roberto Poppiel, Veridiana Maria Sayão, André Carnieletto Dotto, Natasha Valadares dos Santos, Merilyn Taynara Accorsi Amorim, José A.M. Demattê
更新时间: 2020-09-26
摘要:

Studies on soil degradation are essential for environmental preservation. Since almost 30% of the global soils are degraded, it is important to study and map them for improving their management and use. We aimed to obtain a Soil Degradation Index (SDI) based on multi-temporal satellite images associated with climate variables, land use, terrain and soil attributes. The study was conducted in a 2598 km2 area in São Paulo State, Brazil, where 1562 soil samples (0–20 cm) were collected and analyzed by conventional methods. Spatial predictions of soil attributes such as clay, cation exchange capacity (CEC) and soil organic matter (OM) were performed using machine learning algorithms. A collection of 35-year Landsat images was used to obtain a multi-temporal bare soil image, whose spectral bands were used as soil attributes predictors. The maps of clay, CEC, climate variables, terrain attributes and land use were overlaid and the K-means clustering algorithm was applied to obtain five groups, which represented levels of soil degradation (classes from 1 to 5 representing very low to very high soil degradation). The SDI was validated using the predicted map of OM. The highest degradation level obtained in 15% of the area had the lowest OM content. Levels 1 and 4 of SDI were the most representative covering 24% and 23% of the area, respectively. Therefore, satellite images combined with environmental information significantly contributed to the SDI development, which supports decision-making on land use planning and management.

17. 题目: Goethite-humic acid coprecipitate mediated Fenton-like degradation of sulfanilamide: The role of coprecipitated humic acid in accelerating Fe(III)/Fe(II) cycle and degradation efficiency
文章编号: N20092604
期刊: Journal of Hazardous Materials
作者: Huali Yu, Guangfei Liu, Ruofei Jin, Jiti Zhou
更新时间: 2020-09-26
摘要:

While extensive studies found that dissociative and iron mineral-adsorbed humic acid (HA) could either stimulate or inhibit Fenton-like processes, little was known about the influence of iron mineral-coprecipitated HA on Fenton-like reactions. Here, goethite and HA (Gt-HA) coprecipitates having different C:Fe molar ratios (C:Fe = 0.16–0.99) were biologically prepared, and for the first time, investigated for their abilities of H2O2 activation and catalytic degradation of sulfanilamide. For system containing Gt-HA with the optimal C:Fe ratio of 0.30, over 91.1% of sulfanilamide (10 mg/L) was removed in 2 h, which was 46.2% higher than that of the control Gt system. Additionally, H2O2 decomposition, •OH production, and organic carbon removal in Gt-HA systems were all more efficient than those in Gt system. Higher carbon moieties stability and lower micropore surface area of Gt-HA decreased the competition for •OH and H2O2, thus helped to improve degradation efficiency. Electrochemical analysis, quenching experiments, and Fe species detection showed that the coprecipitated HA could serve as electron shuttle and complex with Fe(III) mainly via carboxyl groups at octahedral sites to improve Fe(III)/Fe(II) transformation. This study improved our understanding of Fe(III)/Fe(II) cycling in Fe‒C coprecipitates and demonstrated the potential of developing Fe‒C coprecipitates as efficient catalysts in Fenton-like processes.

18. 题目: Hydrological management constraints on the chemistry of dissolved organic matter in the Three Gorges Reservoir
文章编号: N20092603
期刊: Water Research
作者: Ding He, Kai Wang, Yu Pang, Chen He, Penghui Li, Yunyun Li, Shangbin Xiao, Quan Shi, Yongge Sun
更新时间: 2020-09-26
摘要:

Reservoirs are well known as a far-reaching human modification on the functions of natural river networks. However, changes in the chemistry and reactivity of dissolved organic matter (DOM) responding to hydrological management for water retention structures, and its influence on the river carbon cycle, remain poorly understood. Here we show that hydrological management does shape the molecular composition of DOM in the world's largest Three Gorges Reservoir, as revealed by optical spectroscopy and ultrahigh-resolution mass spectrometry. Relatively higher terrestrial input, molecular complexity, isomeric complexity, and environmental stability of DOM were observed during the storage period, whereas the inverse occurred during the drainage period. The results demonstrate that the hydrodynamic processes, which are mainly controlled by water intrusion from mainstream to tributaries, are likely the underlying mechanism controlling DOM chemistry. Integrated with observations from worldwide river reservoirs, the DOM degradation experiments suggest that reservoir hydrological management would enhance DOM mineralization, thereby increase CO2 emission and change the river carbon cycle.

19. 题目: THE DARK SIDE OF BLACK GOLD: Ecotoxicological aspects of biochar and biochar-amended soils
文章编号: N20092602
期刊: Journal of Hazardous Materials
作者: Paulina Godlewska, Yong Sik Ok, Patryk Oleszczuk
更新时间: 2020-09-26
摘要:

Biochar, a product of biomass pyrolysis, is characterized by significant surface area, porosity, high water holding capacity, and environmental persistence. It is perceived as a material that can counteract climate change due to its high carbon stability and is also considered suitable for soil amendment (fertility improvement, soil remediation). However, biochar can have a toxic effect on organisms as harmful substances may be present in it. This paper reviews the literature regarding the current knowledge of harmful substances in biochar and their potential negative impact on organisms from different trophic levels. The effects of biochar on the content and toxicity of harmful substances in biochar-amended soils are also reviewed. Application of biochar into soil does not usually have a toxic effect and very often stimulate plants, bacteria activity and invertebrates. The effect however is strictly determined by type of biochar (especially the feedstock used and pyrolysis temperature) as well as contaminants content. The pH, electrical conductivity, polycyclic aromatic hydrocarbons as well as heavy metals are the main factor usually responsible for biochar toxicity.

20. 题目: Constrained optimal foraging by marine bacterioplankton on particulate organic matter
文章编号: N20092601
期刊: Proceedings of the National Academy of Sciences
作者: Yutaka Yawata, Francesco Carrara, Filippo Menolascina, Roman Stocker
更新时间: 2020-09-26
摘要: Optimal foraging theory provides a framework to understand how organisms balance the benefits of harvesting resources within a patch with the sum of the metabolic, predation, and missed opportunity costs of foraging. Here, we show that, after accounting for the limited environmental information available to microorganisms, optimal foraging theory and, in particular, patch use theory also applies to the behavior of marine bacteria in particle seascapes. Combining modeling and experiments, we find that the marine bacterium Vibrio ordalii optimizes nutrient uptake by rapidly switching between attached and planktonic lifestyles, departing particles when their nutrient concentration is more than hundredfold higher than background. In accordance with predictions from patch use theory, single-cell tracking reveals that bacteria spend less time on nutrient-poor particles and on particles within environments that are rich or in which the travel time between particles is smaller, indicating that bacteria tune the nutrient concentration at detachment to increase their fitness. A mathematical model shows that the observed behavioral switching between exploitation and dispersal is consistent with foraging optimality under limited information, namely, the ability to assess the harvest rate of nutrients leaking from particles by molecular diffusion. This work demonstrates how fundamental principles in behavioral ecology traditionally applied to animals can hold right down to the scale of microorganisms and highlights the exquisite adaptations of marine bacterial foraging. The present study thus provides a blueprint for a mechanistic understanding of bacterial uptake of dissolved organic matter and bacterial production in the ocean—processes that are fundamental to the global carbon cycle.

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