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12621. 题目: Effects of planting Caragana shrubs on soil nutrients and stoichiometries in desert steppe of Northwest China
文章编号: N19081309
期刊: CATENA
作者: Yang Yang, Bingru Liu
更新时间: 2019-08-13
摘要: Caragana korshinskii shrubs are widely planted in desert steppe of Northwest China to mitigate desert encroachment. Soil nutrients and stoichiometries reflect the cycling of soil organic matter in ecosystems. Thus, there is a dynamic balance between soil nutrients and stoichiometries due to the establishment of Caragana shrubs in this region. Here, soil nutrients and stoichiometries were characterized with different planting densities of Caragana shrubs (HD, high density, 4530 bundle/hm2; MD, mid density, 3670 bundle/hm2; LD, low density, 2560 bundle/hm2) to explore how the planting of Caragana shrubs affects soil nutrients and stoichiometries in desert steppe of Northwest China. The results showed that soil available phosphorus (AP) and soil total phosphorus (TP) had no significant differences between LD and control (CK) (p > 0.05). Further, soil organic carbon (SOC), soil total nitrogen (TN), and soil alkali-hydrolyzable nitrogen (AN) followed the order of HD > MD > LD > CK, indicating that the planting of Caragana shrubs had an increasing effect to soil nutrients, with the exception of AP and TP (p < 0.05), and the increasing effect gradually died down along soil profile. In addition, the planting of Caragana shrubs significantly affected soil stoichiometries. Specifically, soil N/P and C/P gradually increased with soil depth with fluctuation, while soil C/N decreased with soil depth. Besides, soil water content (SW), AP, AN, and SOC had strong positive effects on soil C/N, while they had strong negative effects on soil C/P and N/P, highlighting the importance of soil properties in determining soil stoichiometries. Overall, our results indicated that planting Caragana shrubs can improve levels of soil nutrients, and HD can be considered the optimal planting density for vegetation restoration in desert steppe. Nevertheless, the threshold of the planting density most favorable for the special climates must be identified through further study in this region.

12622. 题目: Composition of lipids from the First Lusatian lignite seam of the Konin Basin (Poland): relationships with vegetation, climate and carbon cycling during the mid-Miocene Climatic Optimum
文章编号: N19081308
期刊: Organic Geochemistry
作者: Achim Bechtel, Marek Widera, Michał Woszczyk
更新时间: 2019-08-13
摘要: Samples of detrital lignite have been collected for detailed organic geochemical and carbon isotope analyses from the First Lusatian lignite seam at the Adamów, Jóźwin IIB and Tomisławice opencast mines, deposited after the last peak of the Mid-Miocene Climatic Optimum. Carbon isotopic compositions of biomarkers from Polish lignite are reported for the first time. The aim of the study is to improve the chemotaxonomic value of biomarkers by relating the results to existing paleobotanical data, and to gain information about the influencing factors on δ13C of lignite and lipids. Furthermore, biomarker and isotopic proxies are tested for their applicability in paleoclimate studies.The molecular composition of the extracted lipids is highly variable, including leaf-wax n-alkanes in the C23 to C31 range, diterpenoids, hopanoids, and angiosperm-derived triterpenoids, as well as saturated fatty acids, long-chain n-alkanols and n-alkan-2-ones. The relative abundances of mid-chain (C23, C25) n-alkanes and their 1–2‰ higher δ13C values compared to long-chain n-alkanes (C29, C31) argue for a minor contribution of macrophytes (graminoids, etc.) to peat formation, enhanced during periods of raised water level. The presence of ferruginol and dehydroferruginol testifies the contribution of Taxodiaceae. The abundances of pimarane-type diterpenoids and the presence of non-aromatic abietane-derivatives argue for the contribution of Pinaceae. Based on the presence of lupeol and lupane-type triterpenoids, an input of Betulaceae can be concluded. The contribution of further angiosperms cannot be specified based on the composition of pentacyclic triterpenoids. However, the results indicate mixed vegetation, and are in agreement with paleobotanical data highlighting abundant conifers of the Taxodiaceae/Cupressaceae and Pinaceae families, as well as angiosperms of various families (e.g., Nyssa, Quercus, Fagus), including Betulaceae (e.g., Alnus, Betula, Corylus). Based on the relationship between the carbon preference index of n-alkanes and mean annual air temperatures, obtained from a global database of peatlands, an average temperature of 24.5 °C is obtained. This value is significantly higher as estimated from paleobotanical data (15.7–19.7 °C), probably due to the influence of changes in vegetation on carbon preference index.The relative abundances of diterpenoids versus di- plus angiosperm-derived triterpenoids in detrital lignite samples revealed variable contributions of gymnosperms and angiosperms during the middle Miocene. Consistent with these results, a positive relationship exists between the di-/(di- + tri-) terpenoid biomarker ratios and δ13C of lignite samples, indicating the dominating role of varying gymnosperm/angiosperm contributions on the carbon isotopic composition of lignite. The C-isotope data of long-chain n-alkanes, diterpenoids, and angiosperm-derived triterpenoids co-vary within the profiles, arguing for an overall control of changes in δ13C of atmospheric CO2 on δ13C of plant lipids. Fluctuations in δ13C of individual compounds may also be related to changes in carbon cycling within the peat, humidity and air temperature. The influence of local variations in ambient CO2 (e.g., the canopy effect) cannot be excluded.

12623. 题目: Production of long-chain n-alkyl lipids by heterotrophic microbes: new evidence from Antarctic lakes
文章编号: N19081307
期刊: Organic Geochemistry
作者: Xin Chen, Xiaodong Liu, Yangyang Wei, Yongsong Huang
更新时间: 2019-08-13
摘要: Long-chain n-alkyl lipids are traditionally ascribed to an origin from terrestrial vascular plants because these compounds are major constituents of higher plant leaf waxes. Over the past half century, numerous studies have taken advantage of these sedimentary biomarkers and their isotopic ratios to reconstruct paleo-environmental and paleo-climatological changes at a variety of time scales. However, it is uncertain and extremely difficult to determine if these compounds can also derive from microbes because of the prevalence of higher plants in most environments around the globe. Here we show, for the first time from natural sediment samples, that long-chain n-alkyl lipids can predominantly originate from aquatic microbial sources at three high-latitude (>69°S latitude) Antarctic lakes, where no vascular plants are present in the surrounding land mass. The high carbon isotopic values (up to –12‰) of these long-chain n-alkyl lipids exclude the possibility that these compounds are transported by wind from adjacent vegetated land masses. Instead, these isotope values are similar to lipids produced by aquatic microbial mats with an average bulk δ13C value of –14.2±1.7‰, indicating heterotrophic microbes are the likely source of these long-chain n-alkyl lipids. For comparison, we also show that when even small amount of vascular plants and mosses are present in the study region, for instance at Long Lake (∼ 62°S latitude) in the Antarctic Peninsula, the carbon isotopic values of sedimentary long-chain n-alkyl lipids decline dramatically, suggesting a rapid proportional increase in the relative contribution of leaf wax sources to total long-chain n-alkyl lipid inventory in lake sediments.

12624. 题目: Identification of phenyldibenzothiophenes in coals and the effects of thermal maturity on their distributions based on geochemical data and theoretical calculations
文章编号: N19081306
期刊: Organic Geochemistry
作者: Zhili Zhu, Meijun Li, Youjun Tang, Ling Qi, Junying Leng, Xiaoqiang Liu, Hong Xiao
更新时间: 2019-08-13
摘要: All four phenyldibenzothiophene (PhDBT) isomers were unequivocally identified in coals for the first time by the co-injection of authentic standards and comparison of the retention indices with those reported in previous studies. Based on density functional theory (DFT) calculations, the relative thermodynamic stability order of the phenyldibenzothiophene isomers (PhDBTs) was determined to be 3-PhDBT > 2-PhDBT > 4-PhDBT > 1-PhDBT. All PhDBT isomers were observed in a suite of coals from the Junggar and Ordos basins, and the effects of thermal maturity on their distributions were systematically investigated. Based on geochemical data and theoretical calculations, two phenyldibenzothiophene maturity indicators, i.e., PhDR1 (2-PhDBT/4-PhDBT) and PhDR2 ((2-PhDBT + 3-PhDBT)/4-PhDBT), are proposed. For high maturity coals (≥ 0.96 %Ro), PhDR1 and PhDR2 increase gradually with increasing thermal maturity. Two preliminary calibrations of these parameters against measured %Ro were made: %Rc = 0.60 × PhDR1 + 1.00 (≥ 1.00 %Ro) and %Rc = 0.30 × PhDR2 + 1.00 (≥ 1.00 %Ro). Compared to their corresponding methylated counterparts, phenyldibenzothiophenes are particularly useful as molecular markers of maturity at higher levels of thermal stress and provide a molecular assessment for sedimentary rocks containing types II and III kerogens where few biomarker parameters are available. PhDBTs in coals are likely to be generated during diagenesis/catagenesis as intermediate products in the formation of more condensed heterocyclic polycyclic aromatic compounds, such as triphenyleno[1,12-bcd]thiophene and benzobisbenzothiophenes, which were detected in the highly mature samples. This study broadens the current understanding of the occurrence, distribution, geochemical significance, and origin of phenyldibenzothiophenes in sedimentary organic matter.

12625. 题目: Depthprofile distribution of Cs and its toxicity for canola plants grown on arid rainfed soils as affected by increasing K-inputs
文章编号: N19081305
期刊: Ecotoxicology and Environmental Safety
作者: Amal A.A. ElShazly, Mohamed H.H. Abbas, Ihab M. Farid, Magdy Rizk, Ahmed A. Abdelhafez, Hassan H. Abbas, Soliman M. Soliman, Mamdouh F. Abdel Sabour, Ibrahim Mohamed
更新时间: 2019-08-13
摘要: Radioactive cesium (Cs) is more likely to be trans-located via rainfall into surrounding environments. Upon Cs-contaminated water reaching soil, Cs is retained on soil components, mainly organic matter and clay fraction. This study aims are i) comparing the relative ability of five arid soils, differing in their textural and chemical properties, to accumulate Cs when subjected to Cs-artificially contaminated rain droplets and ii) testing whether K fertilizer can decrease the uptake of Cs and its translocation within plants or not. A lab experiment was then conducted to simulate artificial rain droplets contaminated with 1000 becquerel (Bq) of 134Cs L−1 precipitated on soil columns each of 10.5 cm inner diameter at a rate of 1.15 mL cm−2 over a period of 2-months. At least 89% of 134Cs accumulated within the uppermost 5-cm layer of these soils. Another greenhouse experiment was set to test the hypothesis which indicates that Cs uptake increases unexpectedly by supplying plants with K-fertilizers. In this experiment, canola (Brassica napus L.) seeds were cultivated into three K-deficient soils (Typic Haplotorrent, Typic Haplocalcid, and Typic Torripsamment) which were contaminated with 100 mg Cs kg−1 soil (stable-Cs was used instead of radioactive-Cs to designate its behavior on the long run). Canola plants were fertilized with 0, 80 and 120 mg K2SO4 kg−1 soil. Results carried on Typic Haplotorrent soil confirmed the aforementioned assumption as K-addition increased Cd-uptake up to 40.1%. Contradictory results were achieved in the other two soils where Cs-uptake decreased by 21.5 and 15.3% in Typic Haplocalcid and Typic Torripsamment soils, respectively due to the application of the aforementioned dose of K. In the K non-amended soils, Cs shoot-root translocation factor was >1; yet, it was <1 in response to K addition, regardless of its application rate.

12626. 题目: Reconsideration of heterostructures of biochars: Morphology, particle size, elemental composition, reactivity and toxicity
文章编号: N19081304
期刊: Environmental Pollution
作者: Kun Zhang, Jiefei Mao, Baoliang Chen
更新时间: 2019-08-13
摘要: Great attention has been paid on biochar due to potential application as soil amendment. The majority of research concerning the structural evolution of biochar commonly considered biochar as a whole. However, the knowledge of structural evolution of biochar resulting from physicochemical disintegration is rarely known. Biochars in this study were categorized into sedimented particles, suspended coarse particles and soluble components and ultrafine particles according to their suspension property. It was found out that these categories were significantly different in morphology, particle size, and elemental composition, demonstrating the presence of heterostructures in biochar. Additionally, the oxidizability of these heterogeneous particles was tested by Starch potassium iodide method and it presented that the oxidizability of the sedimented particles from high-temperature biochar was the highest. Based on the analysis of Luminescent bacteria test, the toxicity of the soluble components and ultrafine particles of low-temperature biochar was higher than that of high-temperature biochar. The heterogeneous structure of biochar and its effect proposed in this study is beneficial to individualize design of biochar sustainable application and to understand disintegration process and environmental risk of biochar in biochar-amended soil.
图文摘要:

12627. 题目: Fine roots determine soil infiltration potential than soil water content in semi-arid grassland soils
文章编号: N19081303
期刊: Journal of Hydrology
作者: Zeng Cui, Gao-Lin Wu, Ze Huang, Yu Liu
更新时间: 2019-08-13
摘要: Soil water is the key limiting factor for achieving sustainable revegetation. Soil infiltration rate plays an important role in determining the inputs from precipitation, which is important for the plant growth and groundwater recharge in semi-arid regions. Soil infiltration rate is generally influenced by belowground biomass (BGB), soil water content (SWC) and other soil properties (total soil porosity, soil mean weight diameter and soil organic carbon). The aim of this study is to understand the effects of plant roots, SWC and other soil properties on soil infiltration rate, and to identify the main factor affecting soil infiltration rate. This study investigated the total soil porosity (TP), soil mean weight diameter (MWD), soil organic carbon (SOC), SWC and plant roots of five grasslands (Bromus inermis, Trifolium repens, Panicum virgatum, Medicago sativa and Miscanthus sinensis). An automatic measurement system of point source device was used to quantify the soil infiltration rate. Results showed that SWC significantly affected the initial infiltration rate (P < 0.05), but plant roots gradually became the main factor affecting soil infiltration rate as the increasing infiltration time. The percentage of root volume (PV) of 0–2 mm was positively correlated with infiltration rate, while the PV of >4.5 mm was negatively correlated with infiltration rate. Our results indicated that fine roots could increase soil organic matters and form soil pores, thus more determining the potential of soil infiltration than soil water content during the short-term vegetation restoration in semi-arid regions.

12628. 题目: Influence of pyrolysis parameters on phosphorus fractions of biosolids derived biochar
文章编号: N19081302
期刊: Science of The Total Environment
作者: S. Adhikari, G. Gascó, A. Méndez, A. Surapaneni, V. Jegatheesan, K. Shah, J. Paz-Ferreiro
更新时间: 2019-08-13
摘要: Transforming biosolids into biochar, through pyrolysis, could result in more sustainable waste management. Influence of pyrolysis conditions (temperature, heating rate and residence time) on physico-chemical properties of biosolids (collected at Mount Martha Water Recycling Plant, Melbourne), phosphorus fractions and phosphorus forms was investigated. Twelve different biochar samples were produced at 400, 500 and 600 °C, at two heating rates (5 and 20 °C/min) and at two residence times (30 and 120 min). Biochar yield, pH, electrical conductivity (EC), elements (C, H and N) and BET surface area were analysed. Sequential extraction of P in biosolids and resultant biochars was done using Hedley method. Characterization was completed with SEM images and results from 31P liquid state NMR. Increased temperatures would not only increase the alkalinity, decrease EC and increase the adsorption capacity by increasing the surface area but also convert the readily available P to a less available pool. Therefore, this nutrient might be released to soil slowly over a longer period of time. The results showed that temperature, along with residence time and heating rate, had a significant effect on the characteristics observed. Therefore, all these factors need to be carefully considered when preparing biochar for use as a soil amendment.
图文摘要:

12629. 题目: Benefits and risks of long-term recycling of pharmaceutical sewage sludge on agricultural soil
文章编号: N19081301
期刊: Science of The Total Environment
作者: Mirko Cucina, Anna Ricci, Claudia Zadra, Daniela Pezzolla, Chiara Tacconi, Simone Sordi, Giovanni Gigliotti
更新时间: 2019-08-13
摘要: European policy is direct towards increasing the agricultural reuse of sludge on soil for improving the fertility; however, the effects of long-term pharmaceutical sewage sludge (PSS) application on soil properties are still unknown. Thus, the aim of this work was to evaluate the agronomic and environmental effects on soil after 17 years of organic amendment with PSS derived from daptomycin production. Five different doses of PSS were spread on lands located in Anagni, Central Italy. Physico-chemical soil properties were investigated, as well as total and bioavailable heavy metals, changes in the soil organic matter quality and biochemical functioning.PSS application showed a positive agronomic potential, improving SOM quality, increasing soil humified organic matter and raising plant nutrients. SOM dynamic was different at low and high PSS supplies, as confirmed by the chemical and biochemical analysis (e.g. C biomass, FDA hydrolysis activity, basal respiration, dehydrogenase, urease and phosphatase activities). However, in a long-term agricultural reuse, environmental risks of PSS recycling were related to the increase of some heavy metals (Hg, Zn and Cu) and exchangeable Na.
图文摘要:

12630. 题目: Efficient degradation of refractory organics for carbonate-containing wastewater via generation carbonate radical based on a photoelectrocatalytic TNA-MCF system
文章编号: N19081208
期刊: Applied Catalysis B: Environmental
作者: Feiyang Chen, Ligang Xia, Yan Zhang, Jing Bai, Jiachen Wang, Jinhua Li, Mohammadi Rahim, Qunjie Xu, Xinyuan Zhu, Baoxue Zhou
更新时间: 2019-08-12
摘要: Carbonate widely exist in wastewater and natural water. Here we proposed an efficient refractory organics degradation method for carbonate-containing wastewater via generating carbonate radical based on a photoelectrocatalytic TNA-MCF system. In the system, TiO2 nanotube arrays (TNA) and modified carbon felt (MCF) were used as photoanode and cathode, respectively. HCO3- was used as electrolyte. The results show that the system achieved 85.78% removal rate after 120 min in rhodamine B degradation, which is 30% higher than that using SO42- as electrolyte. The excellent performance is attributed to the strong oxidation of •CO3- to organics, which originates from the reactions between HCO3- and hvb+ on TNA photoanode. It was also generated from the activation of HCO3- with H2O2 and O2•- on MCF cathode. Moreover, the mechanism of •CO3- formation and its efficient degradation of organics were investigated. These results demonstrate that this system has a potential application in refractory organics degradation.

12631. 题目: Biochar increases plant water use efficiency and biomass production while reducing Cu concentration in Brassica juncea L. in a Cu-contaminated soil
文章编号: N19081207
期刊: Ecotoxicology and Environmental Safety
作者: Maria Isidoria Silva Gonzaga, Paulo Silas Oliveira da Silva, José Carlos de Jesus Santos, Luiz Fernando Ganassali de Oliveira Junior
更新时间: 2019-08-12
摘要: Biochar has been recently used as an alternative strategy to improve soil quality and plant growth in metal contaminated soils. However, the effects of biochar on gas exchange parameters such photosynthetic rate (A), water use efficiency (WUE) and instantaneous carboxylation efficiency (ICE) in metal tolerant plant species in contaminated soils is still unknown. Such information is important to understand how different biochar types can influence plant biomass production and metal uptake. Hence, a greenhouse experiment was set up as a completely randomized design combining two types of crop residue biochar (coconut husk (CB) and orange shell (OB) and two rates of application (30 t ha−1 and 60 t ha−1)). A control treatment (no biochar) was also included. The aim of the study was to investigate the influence of biochar on the physiological performance, growth and concentration of copper (Cu) in the shoot of B. juncea plants in a Cu-contaminated soil. Besides reduced growth on the control soil, all other treatments increased plant growth. No toxicity symptom was observed in the plant, confirming its Cu tolerance. Biochar increased plant biomass by approximately 170% and reduced Cu concentration up to 51%. Application of 30 t ha−1 biochar significantly increased net photosynthesis in 59% (CB) and in 34% (OB) while reducing stomatal conductance in 40% and transpiration rate in 14% (CB) and 19% (OB). Application of 60 t ha−1 of biochar reduced stomatal conductance and transpiration rate in 51% and 60% (CB) and 26% and 7% (OB), respectively. All biochars improved the water use efficiency (WUE) in the plants (52–182%) for the instantaneous WUE and 80–162% for the intrinsic (IWUE). Therefore, biochar, especially CB, caused an improved regulation of the stomata aperture so that plant could maintain a high photosynthetic rate while efficiently controlling the use of water. This could be an important mechanism to reduce the excessive uptake of Cu by the plant.

12632. 题目: Underlying dynamics and effects of humic acid on selenium and cadmium uptake in rice seedlings
文章编号: N19081206
期刊: Journal of Soils and Sediments
作者: Hongyu Zhang, Shuyun Xie, Zhengyu Bao, Huan Tian, Emmanuel John M. Carranza, Wu Xiang, Lingyang Yao, Hai Zhang
更新时间: 2019-08-12
摘要: Purpose: Natural organic acids, such as humic acid (HA), play crucial roles in biogeochemistry of anions and cations in soil due to their numerous functional groups on their surfaces. Selenium (Se) and cadmium (Cd) could bind strongly to HA; nevertheless, it is still unclear as to the effects of HA on Se and Cd uptake in rice which will be focused on in this paper. Materials and methods: Pot experiments were carried out at Huazhong Agricultural University, Wuhan City, Hubei Province, China. Agricultural soils were treated with different concentrations of HA (0, 4, and 8 g kg−1 soil) and Se (SeIV or SeVI) (0 and 2 mg kg−1 soil) as well as with base fertilizer 3 days prior to planting. For Cd treatment, experimental soils were treated with Cd (0 and 2 mg kg−1 soil) 1 month before sowing. For element determination, root (after DCB extraction) and shoot samples were digested with a mixed solution of HNO3-HClO4, and the Se and Cd in digest solution were measured by HG-AFS and ICP-MS, respectively. Fe, Se, and Cd in iron plaque were extracted by DCB extraction and measured by AAS, HG-AFS, and ICP-MS, respectively. Results and discussion: HA reduced Se (or Cd)-induced growth stimulation and Se and Cd uptake in rice seedlings, whereas iron plaque formation varied little with different treatments. HA inhibited SeIV (or SeVI) uptake in rice seedlings by reducing Se translocations from soil to iron plaque (or by increasing Se adsorption capacity of iron plaque and decreasing Se transport from iron plaque to root). HA reduced Cd uptake in rice seedlings by reducing Cd transport from soil to iron plaque and from iron plaque to root. Compared with single addition of SeIV or SeVI or HA, adding HA combined with SeIV or SeVI could further reduce Cd uptake in rice seedlings, whereas Se contents of aerial tissues did not change obviously. Conclusions: HA inhibited the accumulation of Se (SeIV or SeVI) and Cd in rice seedlings; nevertheless, the mechanism was different. Compared with adding Se (or HA) alone, application of Se mixed with HA might be a more effective way to produce Se-enriched and Cd-deficient crop in Cd-contaminated soil.

12633. 题目: Effects of oxalic acid on Cr(VI) reduction by phenols in ice
文章编号: N19081205
期刊: Environmental Science and Pollution Research
作者: Nan Wang, Yubo Zhong, Chunli Kang, Tao Tian, Yuhan Wang, Kunkun Xiao, Dan Shang
更新时间: 2019-08-12
摘要: Since Cr(VI) is highly toxic, the environmental reduction of Cr(VI) to Cr(III) has attracted significant attention. Oxalic acid, a primary component of dissolved organic matter (DOM), is widely distributed throughout the natural environment but the reduction of Cr(VI) by oxalic acid is insignificant at the low concentrations present in the environment; however, the reduction of Cr(VI) is accelerated significantly in ice. In terms of combined pollution, Cr(VI) can coexist with other organic pollutants in the environment but the impact of organic pollutants on the reduction of Cr(VI), changes to the organic pollutants themselves, and the role of oxalic acid in these reactions are unknown. In this study, we investigated redox reactions between Cr(VI) and phenolic compounds in ice (− 15 °C) in the presence of oxalic acid and compared these to room temperature redox reactions in aqueous solutions (20 °C). While these redox reactions were negligible in aqueous solution, they were significantly accelerated in ice under acidic conditions, which was primarily attributed to the freeze concentration effect. Oxalic acid has two functions in these redox reactions; the first is to provide the H+ required for the reaction and the second is to serve as a reducing agent. When oxalic acid and phenolic pollutants coexist, Cr(VI) preferentially reacts with the phenolic compounds. Phenol, 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP) were each demonstrated to reduce Cr(VI) in ice, but the reaction rate and overall reactivity of these three phenolic compounds are different.

12634. 题目: From Canals to the Coast: Dissolved Organic Matter and TraceMetal Composition in Rivers Draining Degraded TropicalPeatlands in Indonesia
文章编号: N19081204
期刊: Biogeosciences
作者: Laure Gandois, Alison May Hoyt, Stéphane Mounier, Gaël Le Roux, Charles Franklin Harvey, Adrien Claustres, Mohammed Nuriman, and Gusti Anshari
更新时间: 2019-08-12
摘要: Worldwide, peatlands are important sources of dissolved organic matter (DOM) and trace metals (TM) to surface waters and these fluxes may increase with peatland degradation. In Southeast Asia, tropical peatlands are being rapidly deforested and drained. The black rivers draining these peatland areas have high concentrations of DOM, and the potential to be hotspots for CO2 release. However, the fate of this fluvial carbon export is uncertain, and its role as a trace metal carrier has never been investigated. This work aims to address these gaps in our understanding of tropical peatland DOM and associated elements in the context of degraded tropical peatlands of Indonesian Borneo. We quantified dissolved organic carbon and trace metals concentrations in the dissolved and fine colloidal (< 0.22 µm) and coarse colloidal (0.22–2.7 µm) fractions and characterized the characteristics (δ13C, Absorbance, Fluorescence: excitation-emission matrix and PARAFAC analysis) of the peatland-derived DOM as it drains from peatland canals, flows along the blackwater Ambawang River, and eventually mixes with Kapuas Kecil River before meeting the ocean near the city of Pontianak in West Kalimantan, Indonesia. We observe downstream shifts in indicators of in-stream processing. The increase in the δ13C of DOC, along with an increase in the C1/C2 ratio of PARAFAC fluorophores, and decrease in SUVA (Specific UV Absorbance) along the continuum suggest the predominance pf photo-oxidation. However, we also observe very low dissolved oxygen concentrations, suggesting that oxygen is quickly consumed by microbial degradation of DOM in the shallow layers of water. Black rivers draining degraded peatlands show significantly higher concentrations of Al, Fe, Pb, As, Ni, and Cd. A strong association is observed between DOM, Fe, As, Cd and Zn in the dissolved and fine colloid fraction, while Al is associated to Pb and Ni and present in a higher proportion in the coarse colloidal fraction. We additionally measure the isotopic composition of lead released from degraded tropical peatlands for the first time and show that Pb originates from anthropogenic atmospheric deposition. Degraded tropical peatlands are important sources of DOM and trace metals to rivers and a secondary source of atmospherically deposited contaminants.

12635. 题目: Preliminary study on the electrocatalytic performance of an iron biochar catalyst prepared from iron-enriched plants
文章编号: N19081203
期刊: Journal of Environmental Sciences
作者: Xinqiang Cao, Yingping Huang, Changcun Tang, Jianzhu Wang, David Jonson, Yanfen Fang
更新时间: 2019-08-12
摘要: Eichhornia crassipes is a hyperaccumulator of metals and has been widely used to remove metal pollutants from water, but disposal of contaminated plants is problematic. Biochar prepared from plants is commonly used to remediate soils and sequester carbon. Here, the catalytic activity of biochar prepared from plants enriched with iron was investigated as a potentially beneficial use of metal-contaminated plants. In a 30-day hydroponic experiment, E. crassipes was exposed to different concentrations of Fe(III) (0, 4, 8, 16, 32 and 64 mg/L), and Fe-biochar (Fe-BC) was prepared by pyrolysis of the plant roots. The biochar was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS) and atomic absorption spectrometry (AAS). The original root morphology was visible and iron was present as γ-Fe2O3 and Fe3O4. The biochar enriched with Fe(III) at 8 mg/L (8-Fe-BC) had the smallest specific surface area (SSA, 13.54 m2/g) and the highest Fe content (27.9 mg/g). Fe-BC catalytic activity was tested in the electrocatalytic reduction of H2O2 using cyclic voltammetry (CV). The largest reduction current (1.82 mA/cm2) was displayed by 8-Fe-BC, indicating the highest potential catalytic activity. We report here, for the first time, on the catalytic activity of biochar made from iron-enriched plants and demonstrate the potential for reusing metal-contaminated plants to produce a biochar catalyst.
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12636. 题目: The 210Po/210Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects
文章编号: N19081202
期刊: Marine Chemistry
作者: Yi Tang, Gillian Stewart
更新时间: 2019-08-12
摘要: The deviation from secular equilibrium between the natural radionuclide 210Po (half-life: 138.4 d) and its radioactive grandparent 210Pb (half-life: 22.3 y) has been used to examine particle export from the surface ocean. Here we combine 210Po and 210Pb activity results from three GEOTRACES transects: two transects of the North Atlantic Ocean (GA03: 15–40°N, and GA01: 40–60°N) and one transect of the South Pacific Ocean (GP16: 10–15°S), and estimate 210Po export fluxes at the base of the primary production zone (PPZ) by assuming steady state (SS) without advection or diffusion of the isotopes. The SS 210Po flux was sometimes lower at basin margins than at the open-ocean stations along the transects. High SS 210Po flux estimations derived in the North Atlantic subtropical gyre may be associated with the atmospheric deposition of 210Pb to the surface ocean. In this paper we also question the validity of the SS assumption and discuss the influence of vertical advection and diffusion on the overall 210Po activity balance. The SS model may have underestimated the export flux of 210Po at margin stations in the GA03 and GP16 transects and along the GA01 cruise track. We found that upwelling in the Peruvian coastal region and near the Greenland shelf had a dramatic impact on the estimated 210Po flux balance. Vertical diffusion had limited influence on the 210Po export fluxes along GA03 and GA01 in the North Atlantic whereas it added 210Po export fluxes by as much as 190% in GP16 in the Pacific, especially at the shelf stations 1 and 4. Further, analysis of the partitioning coefficient suggested the importance of small particles in the scavenging of radionuclides. This suggests it is wise to sample small particles along with large particles to determine the ratio of the concentration of particulate organic carbon (POC) to 210Po activity (POC/210Po) for the lower limit of POC export flux estimations. Finally, the observation of the deficit of 210Po relative to 210Pb activity (210Po/210Pb < 1) in seawater concurrent with a deficit of 210Po in particles contradicts our understanding of the conceptual 210Po flux model, which assumes that 210Po activity is more effectively removed from the surface ocean via particles than 210Pb activity. While this observation deserves more attention, we propose two possible solutions: (1) the deficit of total 210Po relative to 210Pb activity in the surface ocean may be due to an input of 210Pb activity instead of/concurrent with a relative removal of 210Po activity via particle export; or (2) the particles collected may not be identical to the ones that have originally created the observed deficit in total 210Po activity.

12637. 题目: Effects of biochar application during different periods on soil structures and water retention in seasonally frozen soil areas
文章编号: N19081201
期刊: Science of The Total Environment
作者: Qiang Fu, Hang Zhao, Heng Li, Tianxiao Li, Renjie Hou, Dong Liu, Yi Ji, Yu Gao, Pengfei Yu
更新时间: 2019-08-12
摘要: Currently, little is known about soil improvement by biochar in seasonally frozen soil areas. It is not clear whether the effects of biochar application on soil physical properties differ based on application period. Therefore, the purpose of this study was to explore the effects of biochar on soil structure and water retention in cold regions during different application periods. Three biochar applications during different periods were set up through field trials (A: in the early stage of freezing, B: in the middle period of thawing and C: addition of half of the biochar in the early stage of freezing and other half in the middle period of thawing), including four biochar application rates (3, 6, 9 and 12 kg·m−2), and no biochar was applied as a control (CK). The results showed that the selection of the biochar application period had a significant effect on the soil structure, but there was no significant difference in the stability of the soil structure. Biochar significantly increased the total porosity (TP) and the content of aggregates with diameters >0.25 mm in the soil, and all 9 kg·m−2 biochar treatments showed the best structural stability index. The improvement of the soil structure led to the enhancement of the water storage capacities. The plant available water content (PAWC) increased from 0.0638 to 0.0927–0.1767 cm3·cm−3, and this result was significantly related to the increases in soil TP and large aggregates (LAs: >2 mm). The optimum field capacity (FC = 0.372 cm3·cm−3) was obtained when the applied amount was 9 kg·m−2. This was beneficial for the stable storage of soil moisture. However, compared with the CK, none of the treatments in area B increased the liquid water content in the field soil. In summary, we suggest that treatment C9 is the most suitable method for application in seasonally frozen soil areas.
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12638. 题目: Microbial Origin of Excreted DNA in Particular Fractions of Extracellular Polymers (EPS) in Aerobic Granules
文章编号: N19081102
期刊: Water, Air, & Soil Pollution
作者: Paulina Rusanowska, Agnieszka Cydzik-Kwiatkowska, Irena Wojnowska-Baryła
更新时间: 2019-08-11
摘要: The study investigated species composition and polysaccharides, proteins, and eDNA content in EPS fractions (soluble, Sol-EPS; loosely bound, LB-EPS; tightly bound, TB-EPS) in nitrifying aerobic granules from reactor operated at a high load of nitrogen 0.5 kg TKN/(m3 × day). In the study, polysaccharides predominated in Sol-EPS, whereas proteins were the main component of bound EPS. eDNA was only detectable in TB-EPS. In Sol-EPS, eDNA originating from Pseudomonales predominated; species belonging to Pseudomonales produce glue-like polysaccharides that enable surface colonization. In all EPS fractions, high abundance of Acinetobacter sp. was noted. In TB-EPS, Thauera sp. was present in high abundance (25.6%) that produce polymers ensuring compact granule structure and that participate in many key metabolic processes for nitrogen conversions in wastewater treatment plants such as heterotrophic nitrification or denitrification. The study indicates that each EPS fraction in aerobic granules represents micro-environment facilitating the growth of species that produce a component of EPS with function essential for surrounding cells.

12639. 题目: Enhanced removal of nitrate and refractory organic pollutants from bio-treated coking wastewater using corncobs as carbon sources and biofilm carriers
文章编号: N19081101
期刊: Chemosphere
作者: Guoping Sun, Junfeng Wan, Yichen Sun, Haisong Li, Chun Chang, Yan Wang
更新时间: 2019-08-11
摘要: The quality of the bio-treated coking wastewater (BTCW) is difficult to meet increasingly stringent coking wastewater discharge standards and future wastewater recycling needs. In this study, the pre-treatment process of BTCW was installed including the two up-flow fixed-bed bioreactors (UFBRs) which were separately filled with alkali-pretreated or no alkali-pretreated corncobs used as solid carbon sources as well as biofilm carriers. Results showed that this pre-treatment process could significantly improve the biodegradability of BTCW and increase the C/N ratio. Thus, over 90% of residual nitrate in BTCW were removed stably. Furthermore, GC-MS analysis confirmed that the typical refractory organic matters decreased significantly after UFBRs pre-treatment. High-throughput sequencing analysis using 16S rRNA demonstrated that dominant denitrifiers, fermentative bacteria and refractory-organic-pollutants-degrading bacteria co-existed inside the UFBRs system. Compared with no alkali-pretreated corncobs, alkali-pretreated corncobs provided more porous structure and much stable release of carbon to guarantee the growth and the quantity of the functional bacteria such as denitrifiers. This study indicated that the UFBRs filled with alkali-pretreated corncobs could be utilized as an effective alternative for the enhanced treatment of the BTCW.
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12640. 题目: Adsorptive Removal of Aqueous Phase Copper (Cu 2+ ) and Nickel (Ni 2+ ) Metal Ions by Synthesized Biochar–Biopolymeric Hybrid Adsorbents and Process Optimization by Response Surface Methodology (RSM)
文章编号: N19081007
期刊: Water, Air, & Soil Pollution
作者: Subrata Biswas, Bhim Charan Meikap, Tushar Kanti Sen
更新时间: 2019-08-10
摘要: This research work is focused on the synthesis, characterization, and application of cost-effective biochar–biopolymeric hybrid adsorbents from waste agricultural biomass and sodium alginate. The adsorbents were characterized by BET (Brunauer–Emmett–Teller), FTIR (Fourier transform infrared), XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy), and bulk density measurement. The performance of the synthesized hybrid adsorbents has been tested for the removal of aqueous phase Ni2+ and Cu2+ metal ions at a concentration range of 25 to 100 mg/L, adsorbent dose of 1–3 g/L, and system temperature of 298–308 K, respectively. The effect of various physicochemical process parameters such as solution pH, adsorbent dose, initial metal ion concentration, temperature, and presence of salts on metal ion adsorption has been studied here, and experimental process parameters are being optimized by response surface methodology (RSM). The model was fitted well with the experimental data. Various kinetic models, namely, pseudo-first-order, pseudo-second-order, and Weber–Morris, have been fitted with batch experimental data, and the mechanism of adsorption has been identified. The maximum Langmuir monolayer adsorption capacity for Cu2+ and Ni2+ were 112 and 156 mg/g, respectively, which are comparative to other published adsorbent’s capacity data under similar experimental conditions. Thermodynamic parameter studies showed that the system was endothermic and spontaneous in nature.

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