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25121. 题目: Effects of long‐term straw return on soil organic carbon storage and sequestration rate in North China upland crops: A meta‐analysis
文章编号: N20013011
期刊: Global Change Biology
作者: Medhn Berhane Hagos, Miao Xu, Zhiying Liang, Jianglan Shi, Gehong Wei, Xiaohong Tian
更新时间: 2020-01-30
摘要: Soil organic carbon (SOC) is essential for soil fertility and climate change mitigation, and carbon can be sequestered in soil through proper soil management, including straw return. However, results of studies of long‐term straw return on SOC are contradictory and increasing SOC stocks in upland soils is challenging. This study of North China upland agricultural fields quantified the effects of several fertilizer and straw return treatments on SOC storage changes and crop yields, considering different cropping duration periods, soil types, and cropping systems to establish the relationships of SOC sequestration rates with initial SOC stocks and annual straw C inputs. Our meta‐analysis using long‐term field experiments showed that SOC stock responses to straw return was greater than that of mineral fertilizers alone. Black soils with higher initial SOC stocks also had lower SOC stock increases than did soils with low initial SOC stocks (fluvo‐aquic and loessial soils) following applications of nitrogen‐phosphorous‐potassium (NPK) fertilizer and NPK+S (straw). Soil C stocks under the NPK and NPK+S treatments increased in the greater‐than‐20‐year duration period, while significant SOC stock increases in the NP and NP+S treatment groups was limited to the 11‐20‐year period. Annual crop productivity was higher in double‐cropped wheat and maize under all fertilization treatments, including control (no fertilization), than in the single‐crop systems (wheat or maize). Also, the annual soil sequestration rates and annual straw C inputs of the treatments with straw return (NP+S and NPK+S) were significantly positively related. Moreover, initial SOC stocks and SOC sequestration rates of those treatments were highly negatively correlated. Thus, long‐term straw return integrated with mineral fertilization in upland wheat and maize croplands leads to increased crop yields and SOC stocks. However, those effects of straw return are highly dependent on fertilizer management, cropping system, soil type, duration period, and the initial SOC content.

25122. 题目: Hotspots of biotic compositional change in lakes along vast latitudinal transects in northern Canada
文章编号: N20013010
期刊: Global Change Biology
作者: Émilie Saulnier‐Talbot, Dermot Antoniades, Reinhard Pienitz
更新时间: 2020-01-30
摘要: Ecotones mark zones of rapid change in ecological structure at various spatial scales. They are believed to be particularly susceptible to shifts caused by environmental transformation, making them key regions for studying the effects of global change. Here, we explored the variation in assemblage structure of aquatic primary producer and consumer communities across latitudinal transects in northeastern North America (Québec‐Labrador) to identify spatial patterns in biodiversity that indicated the location of transition zones across the landscape. We analyzed species richness and the cumulative rate of compositional change (expressed as beta‐diversity) of diatoms and chironomids to detect any abrupt shifts in the rate of spatial taxonomic turnover. We used principal coordinates analysis to estimate community turnover with latitude, then applied piecewise linear regression to assess the position of ecotones. Statistically significant changes in assemblage composition occurred at 52°N and 55°N, corresponding to the transition between closed and open crown forest, and to the southern onset of the forest tundra (i.e. the forest limit), respectively. The spatial distribution of ecotones was most strongly related to air temperature for chironomids and to vegetation‐ and soil‐related chemical attributes of lake water for diatoms, including dissolved organic carbon content and water color. Lakes at mid‐ to high latitudes currently face pressures from rapidly rising temperatures, accompanied by large increases in organic carbon inputs from their catchments, often leading to browning and its associated effects. The biota at the base of food webs in lakes located in transition zones are disproportionately affected by the cascading effects of these multi‐factorial changes, concurrent with pronounced terrestrial greening observed in these regions. Similar patterns of biotic shifts have been observed along alpine aquatic transects, indicating the potential for widespread restructuring of cold, high‐altitude and high‐latitude freshwater communities due to global change.

25123. 题目: Particulate organic matter dynamics in a permafrost headwater stream and the Kolyma River mainstem
文章编号: N20013009
期刊: Journal of Geophysical Research: Biogeosciences
作者: Lisa Bröder, Anya Davydova, Sergey Davydov, Nikita Zimov, Negar Haghipour, Timothy I. Eglinton, Jorien E. Vonk
更新时间: 2020-01-30
摘要: Ongoing rapid arctic warming leads to extensive permafrost thaw, which in turn increases the hydrologic connectivity of the landscape by opening up subsurface flow paths. Suspended particulate organic matter (POM) has proven useful to trace permafrost thaw signals in arctic rivers, which may experience higher organic matter loads in the future due to expansion and increasing intensity of thaw processes such as thermokarst and river bank erosion. Here, we focus on the Kolyma River watershed in Northeast Siberia, the world's largest watershed entirely underlain by continuous permafrost. To evaluate and characterize the present‐day fluvial release of POM from permafrost thaw, we collected water samples every 4‐7 days during the 4‐months open water season in 2013 and 2015 from the lower Kolyma River mainstem and from a small nearby headwater stream (Y3) draining an area completely underlain by Yedoma permafrost (Pleistocene ice‐ and organic‐rich deposits). Concentrations of particulate organic carbon generally followed the hydrograph with highest concentrations during the spring flood in late May/early June. For the Kolyma River, concentrations of dissolved organic carbon showed a similar behavior, in contrast to the headwater stream, where DOC values were generally higher and POC concentrations lower than for Kolyma. Carbon isotope analysis (δ¹³C, Δ¹⁴C) suggested Kolyma‐POM to stem from both contemporary and older permafrost sources, while Y3‐POM was more strongly influenced by in‐stream production and recent vegetation. Lipid biomarker concentrations (high‐molecular‐weight n‐alkanoic acids and n‐alkanes) did not display clear seasonal patterns, yet implied Y3‐POM to be more degraded than Kolyma‐POM.

25124. 题目: Specific surface area and electron donating capacity determine biochar's role in methane production during anaerobic digestion
文章编号: N20013008
期刊: Bioresource Technology
作者: Yong Qin, Xiaosi Yin, Xingkun Xu, Xiangrui Yan, Feng Bi, Weixiang Wu
更新时间: 2020-01-30
摘要: The addition of biochar derived from different materials can have varying effects on anaerobic digestion (AD), depending on its physicochemical properties. Physicochemical properties of biochars, biomethanization performance and microbial communities were examined to evaluate the effectiveness of biochars made from different plant wastes on AD in this study. Results showed that all biochars significantly reduce the lag phases during AD, compared with a control treatment (CK). Woody biochars particularly performed much better than herbal ones. Correlation analysis revealed that specific surface area (SSA) and electron donating capacity (EDC) were the key properties of the plant-feedstock-derived biochar in AD enhancement. Microbial community structure analysis showed that higher SSA and EDC are conducive for the growth of bacteria decomposing glucose, further promoting daily methane production in the early AD stage. The results indicate that it is important to select biochar with higher SSA and EDC to enhance biomethanization in AD systems.
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25125. 题目: Impact of origin and structure on the aggregation behavior of natural organic matter
文章编号: N20013007
期刊: Chemosphere
作者: Peiyun Wei, Fanchao Xu, Heyun Fu, Xiaolei Qu
更新时间: 2020-01-30
摘要: The intermolecular interactions of natural organic matter (NOM) play a key role in the fate and transport of organic carbon and pollutants in environmental and engineered systems. In this study, the impact of origin and structure on the aggregation behavior of NOM was investigated in the presence of naturally abundant cations. The physicochemical properties of NOM were quantified using a range of indices. Thermodynamic analysis suggests that the colloidal stability of NOM was mainly determined by its hydrophobicity (i.e., Lewis acid-base interactions). All NOM can be coagulated by Ca²⁺ owing to the strong cation-NOM interactions, which lead to bridging effect and lower Lewis acid-base interactions. Terrestrial NOM can be coagulated by Mg²⁺ while aquatic NOM cannot, owing to their different hydrophobicity. The critical coagulation concentrations of tested terrestrial NOM in the presence of Ca²⁺ (CCC–Ca) were quite similar at 1.94–4.88 mM despite their different structural properties. The CCC-Ca of tested aquatic NOM varied significantly from 46.89 mM to 110.40 mM depending on their structure. The optical indices including E₂/E₃, FI, and HIX can be potentially used as convenient indicators for assessing the colloidal stability of aquatic NOM for water treatment and risk assessment purposes.
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25126. 题目: Climate reconstructions based on GDGTs and pollen surface datasets from Mongolia and Siberia: Calibrations and applicability to extremely dry and cold environments
文章编号: N20013006
期刊: Biogeosciences
作者: Lucas Dugerdil, Sébastien Joannin, Odile Peyron, Isabelle Jouffroy-Bapicot, Boris Vannière, Bazartseren Boldgiv, and Guillemette Ménot
更新时间: 2020-01-30
摘要: Our understanding of climate and vegetation changes throughout the Holocene is hampered by biases in the proxy representativeness in sedimentary archives. Such potential biases are identified by comparing proxies to modern environments. Consequently, it becomes important to conduct multi-proxy studies and robust calibrations. The taiga-steppes of the Mongolian plateau, ranging from the extremely cold-dry Baikal basin to the Gobi desert, are characterized by low annual precipitation and continental annual air temperature as well as livestock grazing. The characterization of the climate system of this area is crucial for the understanding of Holocene Monsoon Oscillations. This study focuses on the calibration of proxy-climate relationships for pollen and glycerol dialkyl glycerol tetraethers (GDGTs) by comparing large published Eurasian calibrations with a set of 53 new surface samples (moss, soil and surface sediments). We show that: (1) preserved pollen assemblages are clearly imprinted on the extremities of the ecosystem range but mitigated and unclear on the ecotones; (2) for both proxies, inferred relationships depend on the geographical range covered by the calibration database as well as on the sample nature; (3) local calibrations, even those derived to the low range of climate parameters encompassed in the study area, better reconstruct climatic parameters than the global ones by reducing the limits for saturation impact, and (4) a bias in climatic reconstructions is induced by the over-parameterization of the models by addition of artificial correlation. We encourage the application of this surface calibration method to consolidate our understanding of the Holocene climate and environment variations.

25127. 题目: Decreased N₂O and NO emissions associated with stimulated denitrification following biochar amendment in subtropical tea plantations
文章编号: N20013005
期刊: Geoderma
作者: Cheng Ji, Shuqing Li, Yajun Geng, Yiming Yuan, Junzhang Zhi, Kai Yu, Zhaoqiang Han, Shuang Wu, Shuwei Liu, Jianwen Zou
更新时间: 2020-01-30
摘要: Acidic soils are hotspots of nitrous oxide (N₂O) and nitric oxide (NO) and biochar is documented to have the potential for mitigating N₂O and NO. The N₂O and NO emissions associated with soil functional genes and physicochemical properties under biochar amendment remains unclear in acidic soils. Here, we carried out a two-year field study to examine the responses of soil N₂O and NO emissions to biochar amendment in a subtropical tea plantation in China. Measurements of N₂O and NO fluxes were taken from inter-row soils using the static chamber method. We also measured the seasonal changes in soil key nitrogen (N)-cycling functional genes and physicochemical properties. Annual N₂O and NO emissions averaged 27.31 kg N₂O-N ha⁻¹ yr⁻¹ and 8.75 kg NO-N ha⁻¹ yr⁻¹ for the N fertilizer applied plots, which were decreased by 24% and 16% due to biochar application, respectively. In addition, both potential nitrification (PNR) and denitrification (PDR) rates were stimulated by biochar amendment, which significantly increased the abundances of bacterial amoA (AOB), nirK and nosZ genes. Changes in the composition of the N₂O-related microbial functional community were closely associated with soil PNR, pH, DOC, and NO₃⁻-N contents. The ratios of NO/N₂O were mainly lower than 1, suggesting that N₂O was produced mostly through denitrification rather than nitrification. There were negative correlations between soil N₂O and NO emissions and soil PDR and pH, and soil N₂O emissions were negatively correlated with nosZ gene abundances. Together, the decrease in N₂O and NO emissions following biochar application could be largely attributed to the enhanced denitrification process, in which biochar enriched the nirK and nosZ genes abundance, resulting from the enhancement of soil DOC and pH in acidic soils.

25128. 题目: Insight into the magnetic lime coagulation-membrane distillation process for desulfurization wastewater treatment: from pollutant removal feature to membrane fouling
文章编号: N20013004
期刊: Journal of Hazardous Materials
作者: Libing Zheng, Yunyi Jiao, Hui Zhong, Chun Zhang, Jun Wang, Yuansong Wei
更新时间: 2020-01-30
摘要: The high suspended solid (SS) and salts were main issues for flue gas desulfurization wastewater (FGDW). A magnetic lime coagulation (MLC)-membrane distillation (MD) integrated process was firstly applied with a self-made poly (vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) membrane and the pollutants remove feature and membrane fouling were discussed. The SS was nearly 100% removed and magnetic seed significantly accelerate the settleability. The flux was 43.00 kg/m²·h with a salt rejection>99%. It was higher than 13 kg/m²·h in the first 125 h during the 18d continuous test, and the rejection for all cations, anions, total organic carbon (TOC) and total inorganic carbon (TIC) were higher than 99.95%, 99.00%, 98.81%, and 99.65%, respectively. Humic substances and tryptophan with 100-5000 Da were main dissolved organic matter (DOM), which were significantly removed. However, membrane fouling and wetting happened after 150 h. Scaling was the main foulants, while the organic fouling and biofouling were also detected. A new “bricklaying model” was induced to depict the formation of foulant layer, the colloids, organic matters (OMs) and microbe communities act as the “concrete”, while the inorganic crystals (magnesium and calcium oxysulphides) were the “bricks”. This contribution offers a new method for FGDW treatment and the membrane fouling mechanism of MD process.
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25129. 题目: Investigation into lanthanum-coated biochar obtained from urban dewatered sewage sludge for enhanced phosphate adsorption
文章编号: N20013003
期刊: Science of The Total Environment
作者: Jing Li, Bing Li, Haiming Huang, Ning Zhao, Mingge Zhang, Lu Cao
更新时间: 2020-01-30
摘要: Phosphate adsorption using metal-modified biochar has awakened much attention and triggered extensive research. In this study, the effect of lanthanum (La)-modified sludge using impregnation-co-precipitation was used for phosphate adsorption. Consequently, La-coated biochar at a pyrolysis temperature of 600 °C had the highest phosphate adsorption and the lowest heavy metal leaching potential. The treatment of virgin biochar with alkali before La loading was found to be beneficial for the increase of phosphate adsorption capacity. The adsorption kinetics was well depicted by the pseudo-second-order model, and indicating that intraparticle diffusion played a crucial role in the adsorption process. The good fitness between adsorption data and the Langmuir isotherm model showed a maximal adsorption capacity of 93.91 mg/g, where phosphate absorption was highly correlated to its concentration in the solution. The La-coated biochar showed high adsorption capacity when the solution pH varied from 3.0 to 6.0, and was insensitive to the coexisting chloride, nitrate, sulfate, bicarbonate and citrate. Moreover, the adsorption mechanism was further explored by using Zeta potential analysis, FTIR and XPS, indicating that the phosphate is adsorbed through electrostatic attraction in the form of the inner-sphere complexation. All the results suggested that the sludge-based biochar, as a support material for La, could serve as a promising adsorbent for phosphate in real applications.
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25130. 题目: Removal of methylene blue from aqueous solutions by biochar prepared from the pyrolysis of mixed municipal discarded material
文章编号: N20013002
期刊: Science of The Total Environment
作者: John Hoslett, Heba Ghazal, Nour Mohamad, Hussam Jouhara
更新时间: 2020-01-30
摘要: This paper investigates the adsorption of organic compounds in aqueous solution to biochar adsorbent, using methylene blue as an indicator for adsorption. Biochar was produced by the pyrolysis of mixed municipal discarded material in an innovative heat pipe reactor, the pyrolysis temperature was held at 300°C for 12 h. Biochar produced under these conditions was found to have oxygen containing functional groups that are beneficial to the adsorption of methylene blue as well as graphitic structures suggesting potential sites for π-π interactions with methylene blue. Methylene Blue followed the pseudo second order kinetic model with higher R² values than both the pseudo first order kinetic and intraparticle diffusion models. The adsorption also closely fit the Langmuir isotherm rather than the Freundlich model, suggesting monolayer adsorption rather than multilayer adsorption. Maximum adsorption capacity was observed at 7.2 mg/g for initial concentration of 100 mg/l Methylene blue in aqueous solution. The amount of Methylene blue adsorbed increased with increasing initial concentration as expected. The adsorption mechanisms are likely π-π interactions between methylene blue and the graphitic structures in the biochar which are shown to be present in Raman spectroscopy, as well as electrostatic attraction and ionic bonding between negatively charged surface sites on the char and the positive charge on the dissolved methylene blue molecules. The results show that biochar obtained from mixed waste could be employed as a low-cost and effective tool in water treatment for the removal of basic dyes and potentially other organic impurities.
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25131. 题目: A meta-analysis on biochar's effects on soil water properties – New insights and future research challenges
文章编号: N20013001
期刊: Science of The Total Environment
作者: Ifeoma G. Edeh, Ondřej Mašek, Wolfram Buss
更新时间: 2020-01-30
摘要: Biochar can significantly alter water relations in soil and therefore, can play an important part in increasing the resilience of agricultural systems to drought conditions. To enable matching of biochar to soil constraints and application needs, a thorough understanding of the impact of biochar properties on relevant soil parameters is necessary. This meta-analysis of the available literature for the first time quantitatively assess the effect of not just biochar application, but different biochar properties on the full sets of key soil hydraulic parameters, i.e., the available water content (AWC), saturated hydraulic conductivity (K_sat), field capacity (FC), permanent wilting point (PWP) and total porosity (TP). The review shows that biochar increased soil water retention and decreased K_sat in sandy soils and increased K_sat and hence decreased runoff in clayey soils. On average, regardless of soil type, biochar application increased AWC (28.5%), FC (20.4%), PWP (16.7%) and TP (9.1%), while it reduced K_sat (38.7%) and BD (0.8%). Biochar was most effective in improving soil water properties in coarse-textured soils with application rates between 30 and 70 t/ha. The key factors influencing biochar performance were particle size, specific surface area and porosity indicating that both soil-biochar inter-particle and biochar intra-particle pores are important factors. To achieve optimum water relations in sandy soils (>60% sand and <20% clay), biochar with a small particle size (<2 mm) and high specific surface area and porosity should be applied. In clayey soil (>50% clay), <30 t/ha of a high surface area biochar is ideal.
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25132. 题目: Understanding the remote influences of ocean weather on the episodic pulses of particulate organic carbon flux
文章编号: N20012921
期刊: Deep Sea Research Part II: Topical Studies in Oceanography
作者: Henry A. Ruhl, Frederick L. Bahr, Stephanie A. Henson, W. Brett Hosking, Benoit Espinola, Mati Kahru, Patrick Daniel, Patrick Drake, Christopher A. Edwards
更新时间: 2020-01-29
摘要: The biological carbon pump has been estimated to export ∼5–15 Gt C yr−1 into the deep ocean, and forms the principal deep-sea food resource. Irregular, intense pulses of particulate organic carbon (POC) have been found to make up about one-third of the overall POC fluxes at a long-term deep-sea research station influenced by coastal upwelling of the California Current, Station M (34°50′N, 123° W, 4000 m depth). However, the drivers of these pulses have been challenging to quantify. It has long been recognized that ocean currents can result in particles being advected while sinking to the point of collection by a sediment trap. Thus, a sediment trap time series can incorporate material from a dynamic catchment area, a concept sometimes referred to as a statistical funnel. This concept raises many questions including: what are the day-to-day conditions at the source locations of the sinking POC And, how might such 'ocean weather' and related ecosystem factors influence the intense variation seen at the seafloor Here we analyzed three-dimensional ocean currents from a Regional Ocean Modeling System (ROMS) model from 2011 to 2017 to trace the potential source locations of particles sinking at 1000, 100, and 50 m d−1 from an export depth of 100 m. We then used regionally tailored satellite data products to estimate export flux of POC from these locations. For the 100 m d−1 speed, the particles had origins of up to ∼300 km horizontal distance from the sediment trap location, moored at Station M at 3400 m depth., and nearly 1000 km for the 50 m d−1 speed. Particle tracking indicated that, there was considerable inter-annual variation in source locations. Particle source locations tended to originate from the east in the summer months, with higher export and POC fluxes. Occasionally these locations were in the vicinity of highly productive ocean features nearer to the coast. We found significant correlations between export flux of organic carbon from the estimated source locations at 100 m depth to trap-estimated POC fluxes at 3400 m depth. These results set the stage for further investigation into sinking speed distributions, conditions at the source locations, and comparisons with mechanistic biogeochemical models and between particle tracking model frameworks.

25133. 题目: Non-linear temperature sensitivity of litter component decomposition under warming gradient with precipitation addition on the Tibetan plateau
文章编号: N20012920
期刊: Plant and Soil
作者: Wangwang Lv, Lirong Zhang, Haishan Niu, Bowen Li, Qi Wang, Yang Zhou, Yanfen Wang, Lili Jiang, Peipei Liu, Huan Hong, Shugang Jia, Caiyun Luo, Dorji Tsechoe, Huakun Zhou, Shiping Wang
更新时间: 2020-01-29
摘要: Background and aims: Interactive effect of warming and precipitation addition on litter decomposition is still scarce. Moreover, nonlinear response of its temperature sensitivity to warming is not demonstrated due to lack of warming gradient experiment in situ. Methods: we performed a warming gradient experiment (0, ~0.25–0.5, ~1, ~2, and ~4 °C, respectively) using infrared heaters and a precipitation addition treatment in a fully-factorial design for 2-years on the Tibetan Plateau. The responses of mass loss of litter components (i.e. organic matter (OM), soluble cell content (SCC), lignin, cellulose (Ce), hemi-cellulose (Hce), total organic carbon (OC)) and nutrients (total nitrogen (TN) and total phosphorus (TP)) to warming and precipitation addition were determined over 2-years. Results: We found that warming significantly increased annual mass losses of all litter components in both treatment years. Precipitation addition significantly increased annual mass losses of OM, SCC, OC, TN and TP only in the first year due to drought. There were no interactive effects between warming and precipitation addition on litter component decomposition in the semi-arid alpine region. Temperature sensitivities were lowest when soil temperature increased by a mean of about 2.3 °C. There was an inverse relationship between the temperature sensitivity of organic matter decomposition and quality of litter carbon compounds. Conclusions: Our results suggest that soil temperature effects may override soil moisture effects on litter decomposition in the alpine region, and the nonlinear temperature sensitivity of litter decomposition should be estimated using warming gradients. Lower quality of litter carbon compounds had higher temperature sensitivity of organic matter decomposition.

25134. 题目: Changes in soil organic matter and microbial communities after fine and coarse residues inputs from Mediterranean tree species
文章编号: N20012919
期刊: Applied Soil Ecology
作者: Caroline Brunel, Raphael Gros, Thomas Z. Lerch, Anne Marie Farnet Da Silva
更新时间: 2020-01-29
摘要: Trees residues decomposition is a key step in forested ecosystems. In the context of sclerophyllous Mediterranean forests, the effects of residue quality on soil organic matter and microbial communities is still poorly documented. Using a mesocosm experiment, we explored microbial responses (enzyme activities, basal respiration, molecular fingerprints and catabolic profiles) and variations in soil chemical properties (pH, CaCO₃, organic C and N contents, quality of soil organic matter via ¹³C CP/MAS NMR) induced by coarse woody debris (W) or fine residues (i.e. twigs -leaves/needles, hereafter TL) from mono-specific or mixed stands of Pinus halepensis and Quercus ilex, P. sylvestris and Q. pubescens. After a nineteen-month incubation period, we found that the origin of residues (Pinus spp. stand, Quercus spp. stand or mixed stand) shaped the genetic structure of both fungal and bacterial communities. TL inputs led to higher soil N content and increased enzyme activities and bacterial biomass. Aromatic compounds and C to N ratio increased with W inputs, strongly shaped fungal communities and increased tyrosinase activity. Thus, the type of residue and the tree species identity (Quercus spp. vs Pinus spp.) appeared to modulate the balance between fungal and bacterial biomass and soil microbial diversity. Our results revealed that logging residues management, by modulating the type of residues remaining on forest floor, could have significant impacts on soil functioning by modifying both chemical properties (e.g. soil C/N ratio) and microbial structure and functions. These findings need to be supported by in natura studies since deciphering such mechanisms controlling C fluxes in forest soils has important consequences under the context of climate change.

25135. 题目: Impact of biochar on greenhouse gas emissions from constructed wetlands under various influent chemical oxygen demand to nitrogen ratios
文章编号: N20012918
期刊: Bioresource Technology
作者: Fucheng Guo, Junmao Zhang, Xiangyu Yang, Qiang He, Lianggen Ao, Yi Chen
更新时间: 2020-01-29
摘要: Biochar is widely used for nutrient removal in constructed wetlands (CWs); however, its influence on greenhouse gas (GHG) emissions from CWs remains unclear. Here, biochar was used to mitigate the global warming potential (GWP) from CWs and promote the removal of contaminants from simulated domestic wastewater under different influent chemical oxygen demand to nitrogen ratios (COD/N=3, 6, 9, 12). Results demonstrated that biochar could improve the removal of COD, NH+ 4-N, and TN. The average N₂O and CO₂ fluxes were significantly lower and CH₄ fluxes were higher in biochar-added CWs than those in none-biochar CWs. Biochar reduced GWP values of N₂O and CH₄ from 18.5% to 24.0%. N₂O fluxes and GWP decreased, while CH₄ and CO₂ fluxes increased as COD/N ratios increased. Additionally, biochar increased the abundance of Geobacter and denitrifiers such as Hydrogenophaga. Overall, biochar could not only promote the removal of nutrients but also mitigate GWP in CWs.
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25136. 题目: Natural pigments from microalgae grown in industrial wastewater
文章编号: N20012917
期刊: Bioresource Technology
作者: Larissa T. Arashiro, María Boto-Ordóñez, Stijn W.H. Van Hulle, Ivet Ferrer, Marianna Garfí, Diederik P.L. Rousseau
更新时间: 2020-01-29
摘要: The aim of this study was to investigate the cultivation of Nostoc sp., Arthrospira platensis and Porphyridium purpureum in industrial wastewater to produce phycobiliproteins. Initially, light intensity and growth medium composition were optimized, indicating that light conditions influenced the phycobiliproteins production more than the medium composition. Conditions were then selected, according to biomass growth, nutrients removal and phycobiliproteins production, to cultivate these microalgae in food-industry wastewater. The three species could efficiently remove up to 98%, 94% and 100% of COD, inorganic nitrogen and PO₄^3--P, respectively. Phycocyanin, allophycocyanin and phycoerythrin were successfully extracted from the biomass reaching concentrations up to 103, 57 and 30 mg/g dry weight, respectively. Results highlight the potential use of microalgae for industrial wastewater treatment and related high-value phycobiliproteins recovery.
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25137. 题目: Sediment release of dissolved organic matter to the oxygenminimum zone off Peru
文章编号: N20012916
期刊: Biogeosciences
作者: Alexandra N. Loginova, Andrew W. Dale, Frédéric A. C. LeMoigne, Sören Thomsen, Stefan Sommer, Klaus Wallmann, and Anja Engel
更新时间: 2020-01-29
摘要: The eastern tropical South Pacific (ETSP) represents one of the most productive areas in the ocean that is characterized by a pronounced oxygen minimum zone (OMZ). Particulate organic matter (POM) that sinks out of the euphotic zone is supplied to the anoxic sediments and utilized by microbial communities. The degradation of POM is associated with dissolved organic matter (DOM) production and reworking. The release of recalcitrant DOM to the overlying waters may represent an important organic matter escape mechanism from remineralization within sediments but received little attention in OMZ regions so far. Here, we combine measurements of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) with DOM optical properties in the form of chromophoric (CDOM) and fluorescent (FDOM) DOM from pore waters and near-bottom waters of the ETSP off Peru. We evaluate diffusion–driven fluxes and net in situ fluxes of DOC and DON in order to investigate processes affecting DOM cycling at the sediment–water interface along a transect 12° S. To our knowledge, these are the first data for sediment release of DON and pore water CDOM and FDOM for the ETSP off Peru. Pore-water DOC and DON accumulated with increasing sediment depth, suggesting an imbalance between DOM production and remineralization within sediments. High DON accumulation resulted in very low pore water DOC / DON ratios (> 1) which could be caused by either an imbalance in DOC and DON remineralization, or to the presence of an additional nitrogen source. Diffusion driven fluxes of DOC and DON exhibited high spatial variability. They varied from 0.2–0.1 mmol m⁻² d⁻¹ to 2.52–1.3 mmol m⁻² d⁻¹ and from −0.042–0.02 mmol m⁻² d⁻¹ to 3.32–1.7 mmol m⁻² d⁻¹, respectively. Generally low net in situ DOC and DON fluxes as well as steepening of spectral slope (S) of CDOM and accumulation of humic-like FDOM at the near-bottom waters over time indicated active microbial DOM utilization at the sediment–water interface, potentially stimulated by nitrate (NO₃⁻) and nitrite (NO₂⁻). The microbial DOC utilization rates, estimated in our study, may be sufficient to support denitrification rates of 0.2–1.4 mmol m⁻² d⁻¹, suggesting that sediment release of DOM contributes substantially to nitrogen loss processes in the ETSP off Peru.

25138. 题目: Peroxymonosulfate activation by nitrogen-doped biochar from sawdust for the efficient degradation of organic pollutants
文章编号: N20012915
期刊: Chemical Engineering Journal
作者: Lu Xu, Chenxi Wu, Peihua Liu, Xue Bai, Xinyu Du, Pengkang Jin, Lei Yang, Xin Jin, Xuan Shi, Yong Wang
更新时间: 2020-01-29
摘要: The fabrication of low-cost, high-performance and environmentally friendly carbon-based catalysts capable of activating peroxymonosulfate (PMS) for wastewater treatment applications is still a challenge. In this work, a novel nitrogen-doped biochar (N-biochar) was prepared through a facile one-step calcination method using sawdust and different organic nitrogen-containing compounds as starting materials. It was found that the catalytic activity of the N-biochar relies heavily on the type of nitrogen precursor, the relative amount of sawdust to nitrogen precursor, and the calcination temperature. Different types and amounts of the nitrogen precursor mainly affect the content of total nitrogen and pyridinic nitrogen, and the calcination temperature mainly affects the content of graphitic nitrogen in the N-biochar. Based on a systematic comparison, an optimized N-biochar (N-C-d-4-800) with a higher content of graphitic and pyridinic N, rich defects, larger SSA and porous structure was obtained, and exhibited a superior catalytic activity for activating PMS to oxidize various organic pollutants, such as bisphenol A (BPA), phenol, acetaminophen (AAP) and sulfamethoxazole (SMX). Moreover, the N-C-d-4-800/PMS system can work effectively at a wide pH range and high salinity conditions, despite the background of the real water matrix. The present study highlights the enormous potential of the novel N-biochar prepared from sawdust for wastewater remediation applications.
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25139. 题目: Evolution and stabilization of environmental persistent free radicals during the decomposition of lignin by laccase
文章编号: N20012914
期刊: Chemosphere
作者: Yafang Shi, Kecheng Zhu, Yunchao Dai, Chi Zhang, Hanzhong Jia
更新时间: 2020-01-29
摘要: Soil microbial enzymes may induce lignin decomposition, accompanied by generation of free radicals. The evolution of environmentally persistent free radicals (EPFRs) and reactive oxygen species (ROS) during laccase-catalyzed lignin decomposition remains unclear. Characterization by electron paramagnetic resonance spectroscopy revealed gradually increased concentration of EPFRs, with maximum levels within 6 h that remained constant, accompanied by the increase in g-factor from 2.0037 to 2.0041. The results suggested the generation of oxygen-centered radicals on lignin. The EPFRs produced on solid samples slowly decreased by 17.2% over 17 d. ROS were also detected to have a similar trend as that of the evolution of EPFRs. Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, gel permeation chromatography and nuclear magnetic resonance analyses suggested the demethylation and oxidation of lignin. We clarify the biogeochemical transformation of lignin and potential contributions to the generation of EPFRs and ROS in soil.
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25140. 题目: Contrasting effects of biochar and hydrothermally treated coal gangue on leachability, bioavailability, speciation and accumulation of heavy metals by rapeseed in copper mine tailings
文章编号: N20012913
期刊: Ecotoxicology and Environmental Safety
作者: Mehr Ahmed Mujtaba Munir, Guijian Liu, Balal Yousaf, Md Manik Mian, Muhammad Ubaid Ali, Rafay Ahmed, Ayesha Imtiyaz Cheema, Mu Naushad
更新时间: 2020-01-29
摘要: The purpose of this research was to examine the influence of hydrothermally treated coal gangue (HTCG) with and without biochar (BC) on the leaching, bioavailability, and redistribution of chemical fractions of heavy metals (HMs) in copper mine tailing (Cu-MT). An increase in pH, water holding capacity (WHC) and soil organic carbon (SOC) were observed due to the addition of BC in combination with raw coal gangue (RCG) and HTCG. A high Cu and other HMs concentration in pore water (PW) and amended Cu-MT were reduced by the combination of BC with RCG and/or HTCG, whereas individual application of RCG slightly increased the Cu, Cd, and Zn leaching and bioavailability, compared to the unamended Cu-MT. Sequential extractions results showed a reduction in the exchangeable fraction of Cu, Cd, Pb, and Zn and elevation in the residual fraction following the addition of BC-2% and BC-HTCG. However, individual application of RCG slightly increased the Cu, Cd, and Zn exchangeable fractions assessed by chemical extraction method. Rapeseed was grown for the following 45 days during which physiological parameters, metal uptake transfer rate (TR), bioconcentration factor (BCF), and translocation factor (TF) were measured after harvesting. In the case of plant biomass, no significant difference between applied amendments was observed for the fresh biomass (FBM) and dry biomass (DBM) of shoots and roots of rapeseed. However, BC-2% and BC-HTCG presented the lowest HMs uptake, TR, BCF (BCF_root and BCF_shoot), and TF for Cu, Cd, Cr, Ni, Pb, and Zn in rapeseed among the other amendments compared to the unamended Cu-MT. Overall, these findings are indicative that using biochar in combination with RCG and/or HTCG led to a larger reduction in HMs leaching and bioavailability, due to their higher sorption capacity and could be a suitable remediation strategy for heavy metals in a Cu-MT.
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