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13921. 题目: Climatic significance of the stable carbon isotopic composition of surface soils in northern Iran and its application to an Early Pleistocene loess section
文章编号: N18112512
期刊: Organic Geochemistry
作者: Qiang Wang, Xin Wang, Haitao Wei, Farhad Khormali, Haichao Xie, Jinhui Zhang, Fahu Chen
更新时间: 2018-11-25
摘要: The stable carbon isotopic composition of bulk organic matter (δ13Corg) in paleosols has been widely used as a proxy indicator for reconstructing past vegetation and climate. Previous studies generally show a negative correlation between the δ13Corg values of modern C3 plants and surface soils under C3 plant-dominated ecosystems and mean annual precipitation (MAP). However, the relationship between δ13Corg and MAP varies among different climatic regimes, resulting in uncertainties in paleo-precipitation reconstructions. In this study, we analyzed the δ13Corg values of surface soil samples collected along a north-south climatic gradient in northern Iran, in the western part of arid central Asia (ACA). Our aims were to explore the relationship between surface soil δ13Corg values and climatic factors; to use it to develop a transfer function for ACA; and then to apply the transfer function to a well-dated loess-paleosol sequence (AB1) to reconstruct early Pleistocene (2.4–1.8 Ma) MAP in northern Iran. The results show that: (1) the δ13Corg values of 44 surface soil samples range from –27.56‰ to –23.61‰, with an average of –25.77‰, indicating that the modern natural ecosystem in northern Iran is dominated by C3 vegetation; (2) The δ13Corg values of the surface soil samples are strongly negatively correlated with MAP (y = –0.0079x – 22.8418, R2 = 0.4419, p < 0.001), with a coefficient of –0.79‰/100 mm. We infer that the effects of mean annual temperature (MAT) and elevation on the relationship are minimal; (3) Reconstructed early Pleistocene MAP in northern Iran was ∼649 mm, much wetter than the present day (∼331 mm); (4) The loess δ13Corg values from ACA exhibit similar trends to records from monsoonal Asia, suggesting a similar history of Quaternary climate change between ACA and monsoonal Asia, which is likely related to the growth and decay of Northern Hemisphere ice sheets.

13922. 题目: Composition of soil recalcitrant C regulates nitrification rates in acidic soils
文章编号: N18112511
期刊: Geoderma
作者: Yi Zhang, Siyi Liu, Yi Cheng, Zucong Cai, Christoph Müller, Jinbo Zhang
更新时间: 2018-11-25
摘要: In acidic soils heterotrophic nitrification is considered to be an important NO3 production process. Previous studies have demonstrated that the content of soil C and soil C:N ratio was positively correlated with heterotrophic nitrification. However, relatively high heterotrophic nitrification rates also observed in cultivated black soils, with relatively low soil organic C content and soil C:N ratio compared to forest soils. To obtain a mechanistic understanding of heterotrophic nitrification the simultaneously occurring gross N transformations were quantified in five cultivated soils (SC) and six forest soils (SF) in subtropical region, ten cultivated soils (TC) and seven forest soils (TF) in temperate region subsequently analysed with respect to the soil physicochemical properties (pH, C:N ratio, SOC, TN), the chemical compositions of soil organic C (recalcitrant and labile organic C) and microbial communities (abundance of fungi, bacteria, amoA gene of AOB and AOA). The results showed that a significantly higher heterotrophic nitrification rate was observed in TC (0.52 mg N kg−1 d−1) compared to the other soils. The total content of soil C and soil C:N ratio could not explain the occurrence of heterotrophic nitrification but recalcitrant C fractions of carbonyl C and aromatic C, and the ratio of recalcitrant C to labile C (R:L ratio) was significantly positively correlated with heterotrophic nitrification rates (P < 0.01). This was further confirmed by structural equation modeling (SEM) that the R:L ratio was the most important indicator, suggesting that chemical composition of SOC is likely to be key to explain and predict heterotrophic nitrification rates across a large range of soils including soils high in black carbon such as chernozems, old grassland soils and/or anthropogenic soils such as anthrosols (Terra preta). In addition, heterotrophic nitrification rates were significantly positively correlated with fungal gene copy numbers (P < 0.05), providing a strong indication that fungi might be the predominant organisms carrying out heterotrophic nitrification.

13923. 题目: Accumulation of nitrate and dissolved organic nitrogen at depth in a red soil Critical Zone
文章编号: N18112510
期刊: Geoderma
作者: Huayong Wu, Xiaodong Song, Xiaorui Zhao, Xinhua Peng, Hu Zhou, Paul D. Hallett, Mark E. Hodson, Gan-Lin Zhang
更新时间: 2018-11-25
摘要: Nitrate accumulation has been reported in the top 1 m and subsurface soil (>1 m) across arid to semi-humid regions, but not in humid regions. Nitrate inventories through the whole regolith, referred to collectively as soil and saprolite, in humid regions have received little attention to date, likely due to previously assumed low nitrification rates and large nitrogen (N) losses by severe surface runoff and erosion. In order to understand if and how reactive N exists in the below ground (soil and saprolite) in humid environment, the amount of NO3-N, NH4+-N and dissolved organic N (DON) present in the regolith to a depth of 9 m in a typical red soil Critical Zone was investigated under different land uses (upland, woodland and paddy field). The Red Soil Critical Zone Observatory is located in the subtropical Jiangxi Province, China, with a mean annual precipitation of 1795 mm and mean annual potential evapotranspiration of 1229 mm. The examined regoliths were acidic, highly weathered, and mainly clay loam to clay in texture. Results showed that on average 92% (827 ± 97 kg N ha−1) of NO3-N and 82% (521 ± 153 kg N ha−1) of DON were stored at depth (from a depth of 1 m to the bedrock surface) in the upland regolith, while 92% (283 kg N ha−1) of NO3-N and 78% (820 kg N ha−1) of DON were stored at depth in the woodland regolith. Nitrate N significantly accumulated with depth in the upland regolith from the 1- to 4-m depth interval (p < 0.01), while the inventory (632 ± 75 kg N ha−1) in the top 3-m zone accounted for on average 71% of the total. Dissolved organic N significantly accumulated with depth in the upland regolith from the 0- to 3-m depth interval (p < 0.01), while the inventory (408 ± 75 kg N ha−1) in the top 3-m zone accounted for on average 64% of the total. There was no significant accumulation for NH4+-N throughout the upland regolith (p = 0.35). No substantial accumulation of dissolved N was measured at depth in paddy field regoliths with different cultivation ages. The finding that large reservoirs of reactive N can exist in deep regolith rather than in the routinely investigated solum of subtropical regions shows a missing part of the terrestrial N budget and raises concerns about potential groundwater nitrate pollution.
图文摘要:

13924. 题目: Temporal dynamics and vertical distribution of newly-derived carbon from a C3/C4 conversion in an Ultisol after 30-yr fertilization
文章编号: N18112509
期刊: Geoderma
作者: S. Liu, Z.B. Zhang, D.M. Li, P.D. Hallett, G.L. Zhang, X.H. Peng
更新时间: 2018-11-25
摘要: Long-term fertilization has a considerable effect on the dynamics of soil organic carbon (SOC). However, quantifying the contribution of fertilization practices to SOC is still a challenge. In this study, we selected a 30-yr fertilization experiment planted with a shift from C3 to C4 crops. Our objectives were (i) to determine temporal dynamics of SOC and newly-derived C (fnew) with the cultivation time and their vertical distribution along with soil profile; (ii) to assess the effect of the fertilization on SOC and fnew. Three treatments were involved: no fertilization (Control), NPK application (NPK), and continuously planted with C3 crops adjacent to the experiment as a reference (NAT). The SOC was physically separated into cPOM, fPOM, iPOM, s + c_m and s + c_f fractions, and their δ13C values were determined. Our results show the fnew in the bulk soil and C fractions presented an exponential increase over the cultivation time in the NPK treatment but this was only observed for the bulk soil and the s + c_f fraction in the Control treatment. The fnew had a priority to be stored within microaggregates, and then enriched in the silt and clay sized fraction over time. The SOC and fnew in the bulk soil and C fractions decreased with soil depth so that the difference between the Control and NPK treatments was observed only in the 0–20 cm depth. Our results demonstrate that the long-term fertilization increases the new C proportion in the bulk soil and C fractions but this contribution was limited to the plough layer.
图文摘要:

13925. 题目: Modeling dissolved organic nitrogen dynamics under different N management practices for intensive greenhouse production using an improved WHCNS_veg model
文章编号: N18112508
期刊: Geoderma
作者: Hao Liang, Kelin Hu, William D. Batchelor, Qing Chen, Bing Liang, Baoguo Li
更新时间: 2018-11-25
摘要: Excess dissolved organic nitrogen (DON) leaching occurs due to manure or fresh organic matter application coupled with high irrigation frequency in intensive greenhouse vegetable production systems (GVPS). Quantifying DON leaching is crucial in developing best management practices for intensive GVPS. The objectives of this study were to develop a DON leaching component for the water and N management model for greenhouse vegetables (WHCNS_veg) and to evaluate nitrate and DON leaching under different N management practices. Two seasons of tomato greenhouse experiments with several N management practices were conducted in Shouguang County, Shandong Province in China. The measured soil water content, soil nitrate and DON concentrations, and tomato yield were used to calibrate and evaluate the improved WHCNS_veg model. Results showed that the WHCNS_veg performed well in modeling soil water content, soil nitrate and DON concentrations, and tomato yield, giving normalized root mean square error values of 4.4%, 37.2%, 45.8% and 3.8%, respectively. Manure application significantly enhanced DON leaching, which accounted for 8.8% to 18.7% of the total N leaching under different N management practices. The simulated and measured tomato yield was not sensitive to different N management practices (except for the no N input treatment). However, the amounts of nitrate leaching, DON leaching, and N gas emission (NxO and NH3) under conventional N management were 2.1, 1.3, and 1.1-fold greater than those in the reduced N management treatment, respectively. Reduced N management practices should be recommended in the greenhouse tomato production in North China, which had a relatively high vegetable yield, less environmental impact, and more sustainability. Results indicated that the improved WHCNS_veg model has great potential to optimize N management and assess the environmental impact of GVPS.
图文摘要:

13926. 题目: Fine root biomass and the associated C and nutrient pool under the alder (Alnus spp.) plantings on reclaimed technosols
文章编号: N18112507
期刊: Geoderma
作者: Bartłomiej Świątek, Bartłomiej Woś, Marcin Chodak, Subodh Kumar Maiti, Agnieszka Józefowska, Marcin Pietrzykowski
更新时间: 2018-11-25
摘要: In the study we have analysed the increment of fine-root biomass (FRBI) and the associated pool of carbon and nutrients (N, S, P, K, Ca, Mg, Na) under alder plantings (Alnus incana, A. glutinosa and A. viridis) growing on technosols developed from combustion wastes and extremely poor quaternary sands excavated by sand mining. The control sites were located in natural habitats in the Bieszczady Mountains within the natural range of the occurrence of the investigated alder species. The fine root biomass depended on the type and properties of the technosols substrate but did not differ between the alder species. The highest fine root biomass (>1000 g m−2) was found in the nutrient-poor sandy soils (SS) of a former sand pit, whereas technosols formed from combustion waste was <301 g m−2, and the lowest (below 264 g m−2) was in natural soils. The results indicate an important role of fine roots in the development of the carbon and nutrient pools in technosols. This is particularly important in the case of barren sandy soils where a deficit of nutrients is balanced by an efficient circulation and release of elements in the decomposition process of dead organic matter, largely connected to the fine roots biomass.

13927. 题目: Environmental drivers and stoichiometric constraints on enzyme activities in soils from rhizosphere to continental scale
文章编号: N18112506
期刊: Geoderma
作者: Svenja C. Stock, Moritz Köster, Michaela A. Dippold, Francisco Nájera, Francisco Matus, Carolina Merino, Jens Boy, Sandra Spielvogel, Anna Gorbushina, Yakov Kuzyakov
更新时间: 2018-11-25
摘要: Microbial activity and functioning in soils are strongly limited by carbon (C) availability, of which a great proportion is released by living roots. Rhizodeposition and especially root exudates stimulate microbial activity and growth, and may shift the stoichiometric balance between C, N, and P. Thereby, exudates heighten microbial nutrient demand and acquisition of N and P from organic matter, leading to an increase in enzyme production. Aim of this study was to determine environmental controls of extracellular enzyme production, and hence on potential enzyme activities (Vmax) and substrate affinities (Km). To determine the controlling factors, we worked on four spatial scales from the microscale (i.e. rhizosphere) through the mesoscale (i.e. soil depth) and landscape scale (relief positions), and finally to the continental scale (1200 km transect within the Coastal Cordillera of Chile). Kinetics of seven hydrolyzing enzymes of the C, N, and P cycles (cellobiohydrolase, β‑glucosidase, β‑xylosidase, β‑N‑acetylglucosaminidase, leucine‑aminopeptidase, tyrosine‑aminopeptidase, and acid phosphatase) were related to soil texture, C and N contents, pH, and soil moisture via redundancy analysis (RDA). Potential activities of C, N, and P acquiring enzymes increased up to 7-times on the continental scale with rising humidity of sites and C and N contents, while substrate affinities simultaneously declined. On the landscape scale, neither Vmax nor Km of any enzyme differed between north and south slopes. From top- to subsoil (down to 120 cm depth) potential activities decreased (strongest of aminopeptidases under humid temperate conditions with up to 90%). Substrate affinities, however, increased with soil depth only for N and P acquiring enzymes. Affinities of cellobiohydrolase and β‑xylosidase, on the contrary, were 1.5- to 3-times higher in top- than in subsoil. Potential activities of N and P acquiring enzymes and β‑glucosidase increased form bulk to roots. Simultaneously, substrate affinities of N and P acquiring enzymes declined, whereas affinities of β‑glucosidase increased. These trends of activities and affinities in the rhizosphere were significant only for acid phosphatase. The RDA displayed a strong relation of potential activities of C and P acquiring enzymes and β‑N‑acetylglucosaminidase to C and N contents in soil as well as to the silt and clay contents. Aminopeptidase activity was mainly dependent on soil moisture and pH. We conclude that substrate availability for microorganisms mainly determined enzyme activity patterns on the continental scale by the humidity gradient. Patterns on the meso- and microscale are primarily controlled by nutrient limitation, which is induced by a shift of the stoichiometric balance due to input of easily available C by roots in the rhizosphere.

13928. 题目: Effect of soil aggregate size and long-term contrasting tillage, stubble and nitrogen management regimes on CO2 fluxes from a Vertisol
文章编号: N18112505
期刊: Geoderma
作者: S.H. Reeves, J. Somasundaram, W.J. Wang, M.A. Heenan, D. Finn, R.C. Dalal
更新时间: 2018-11-25
摘要: Soil aggregates are the ‘building blocks’ of soil structure. Aggregation dominantly influences the physico-chemical and biological properties of soil. Farm management practices can alter soil aggregation, which can potentially influence carbon dioxide (CO2) fluxes. We examined the effect of soil aggregate size on CO2 fluxes in a Vertisol following 47 years of contrasting management regimes, namely no-till (NT) or conventional till (CT), stubble retention (SR) or burning (SB), and without nitrogen (N) application (0 N) or with 90 kg N ha−1 year−1 (90 N). Aggregate size significantly affected CO2 fluxes over a 21-day incubation period, with the smallest aggregate size of <2 mm having the highest cumulative CO2 flux, followed by the 2–4 mm then 4–8 mm aggregates. The observed differences were mainly caused by total organic carbon contents, as well as substrate accessibility. Over all aggregate sizes, the SR treatments had higher CO2 fluxes compared to SB treatments due to additional substrate availability for microbial respiration. Cumulative CO2 flux was higher for the N fertilised treatments than the unfertilised treatments, likely as a result of increased soil organic matter content and the reduced C:N ratio. Fluxes of CO2 from small and intermediate aggregates were lower for NT compared to CT when 90 N fertiliser was applied, but not significantly different without N fertiliser application. This study identified the underlying controlling factors of CO2 flux from different aggregate sizes in a Vertisol under long term contrasting management regimes.

13929. 题目: Combined effects of temperature and precipitation on soil organic carbon changes in the uplands of eastern China
文章编号: N18112504
期刊: Geoderma
作者: Liming Zhang, Qiaofeng Zheng, Yaling Liu, Shaogui Liu, Dongsheng Yu, Xuezheng Shi, Shihe Xing, Hanyue Chen, Xieyu Fan
更新时间: 2018-11-25
摘要: Temperature and precipitation simultaneously influence the soil organic carbon (SOC) in agroecosystems. While these parameters' individual impacts have been extensively studied, their combined effects remain poorly understood at a regional scale. Thus we conducted this study to quantify the combined influence of temperature and precipitation on the SOC in upland-crop fields of the northern Jiangsu Province in eastern China. This quantification was achieved by using the DeNitrification-DeComposition (DNDC, version 9.5) model with the most detailed upland soil database in China. The model simulations indicated that under a scenario where the air temperature (T) increased by 2 °C (T2) and the precipitation (Prec) simultaneously decreased by 20%, the upland soils in the study region were estimated to a sequestered 39.10 Tg C from 2010 to 2039. Meanwhile, a scenario with T2 and a simultaneous increase in Prec by 20% led to a lower C sequestration of 37.39 Tg C. We found that the respective C sequestration from the combined effects of T and Prec in the above two scenarios was 1.24 (or 2.12) Tg C less compared to the sum of their individual effects. Moreover, if the increase of T changed from 2 °C to 4 °C, and the Prec continued to decrease (or increase) by 20%, the C sequestration was 34.69 (or 33.64) Tg C, which was 3.60 (or 3.82) Tg C lower than the sum of the individual effects. Our analysis of the combined effects of T and Prec on the SOC changes suggested that future warming and Prec changes in this region may cause a decrease in the SOC sequestration, but the upland agroecosystems will still serve as a long-term sink for atmospheric CO2 due to the high application rates of chemical fertilizer and farmyard manure. Furthermore, the separate and combined effects of temperature and precipitation on the SOC changes in the different upland soil groups varied widely due to the heterogeneity of soil properties, physicochemical conditions and fertilizer practices. This result emphasized the importance of using fine scale soil datasets and the need to understand the intricacies in the soil carbon sequestration potential at a regional scale in a changing climate.

13930. 题目: Insights into the interactions between triclosan (TCS) and extracellular polymeric substance (EPS) of activated sludge
文章编号: N18112503
期刊: Journal of Environmental Management
作者: Zi-run Yan, Hui-shan Meng, Xue-yuan Yang, Yu-ying Zhu, Xiu-yan Li, Juan Xu, Guo-ping Sheng
更新时间: 2018-11-25
摘要: Triclosan (TCS) contaminant has aroused wide concerns due to the high risk of converting into toxic dioxin in aquatic environments. During the wastewater treatment process, considerable amounts of TCS are accumulated in activated sludge but the mechanisms are still unclear. Especially, roles of extracellular polymeric substances (EPS), the main components of activated sludge, in TCS removal have never been addressed. In this work, the binding properties of loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) of activated sludge to TCS are investigated by fluorescence quenching approach. The influences of aquatic conditions including solution pH, ionic strength and temperature on the interactions between EPS and TCS are explored. Possible interaction mechanisms are discussed as well as the corresponding environmental implication. Results indicate that binding processes of EPS to TCS are exothermic mainly driven by the enthalpy changes. The proteins components in EPS dominate the interactions between EPS and TCS by hydrogen bond and hydrophobic interaction. The binding strength could be improved under the condition of weak alkaline and relative high ionic strength. Generally, LB-EPS exhibit stronger binding ability to TCS than TB-EPS under neutral environment, playing more crucial roles in the binding process. This work highlights the important contributions of EPS to TCS removal, that is beneficial to comprehensively understand the migration of TCS in activated sludge system.
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13931. 题目: The evolution of compost stability and maturity during the full-scale treatment of the organic fraction of municipal solid waste
文章编号: N18112502
期刊: Journal of Environmental Management
作者: Alessandra Cesaro, Anna Conte, Vincenzo Belgiorno, Antonietta Siciliano, Marco Guida
更新时间: 2018-11-25
摘要: Composting is the method most commonly applied worldwide for the recovery of the source sorted organic waste. The process aims at stabilizing the organic matter, so as to produce a material with soil improver properties, referred to as compost. The effective recovery of the organic waste fraction via composting implies compost safe use on soil. In this view, the assessment of compost characteristics, depending on both the quality of the input material and the process operation, is fundamental. At full scale, the process monitoring usually relies on parameters enabling the indirect control of its evolution, whereas the biological stability and maturity are usually evaluated on the final product. Aim of this work was in assessing both biological stability and maturity during the composting process of the organic fraction of municipal solid waste performed at industrial scale. Representative samples were collected over time in a composting facility operating in the South of Italy and analysed by the dynamic respirometric index, the content of humic substances as well as by their phytotoxicity. Results showed the key role of stability and maturity parameters in the monitoring of composting processes. Experimental outcomes further addressed wider considerations on the operational procedures for a sustainable compost production process.

13932. 题目: The potential power and pitfalls of using the X-ray fluorescence molybdenum incoherent: Coherent scattering ratio as a proxy for sediment organic content
文章编号: N18112501
期刊: Quaternary International
作者: C.A. Woodward, P.S. Gadd
更新时间: 2018-11-25
摘要: Changes in organic matter concentration in sediment cores from natural archives such as lakes and wetlands can be a valuable tool in paleoenvironmental studies. The molybdenum incoherent: coherent scattering ratio (moly ratio) from the Itrax core scanner offers the potential to measure down core changes in sediment organic content. The analysis is rapid, high resolution and does not destroy samples. We built upon previous studies of the power and potential pitfalls of using the moly ratio as a proxy for organic content in sediments. An important difference between our study and previous work is that we accounted for the total mass of moisture and organic content in the sediment using loss on ignition. This had the advantage over total organic carbon measurement of being able to account for all light elements (H, C, N, and O) that would affect the moly ratio. We used redundancy analysis to determine that both organic and moisture content can have large, independent, and variable effects on the moly ratio. It is therefore critical that moisture and organic content have a constant relationship with each other in a core. Samples with higher moisture to organic content ratios can over predict organic content and vice versa. The effect of moisture only accounted for 30% of the prediction error for the moly ratio in our study. We argue that a large part of remaining error reflects sample heterogeneity. XRF core scanning and organic content determination from sub-samples can show different results because the mean sediment composition is different. We recommend that calibration sub-samples are large (≥2 cm3) in potentially heterogeneous sediments, authors should report the sample size used for calibration purposes, and multiple scans of the core may be needed. If organic content is an important proxy for an environmental reconstruction, we recommend calibration of the moly ratio and confirming a constant relationship between moisture and organic content. Thoughtful selection of sub-samples for this purpose could mean that calibration can be performed with a minimum of extra effort.

13933. 题目: Long-term effects of biochar addition and straw return on N2O fluxes and the related functional gene abundances under wheat-maize rotation system in the North China Plain
文章编号: N18112423
期刊: Applied Soil Ecology
作者: Xingren Liu, Jianqiang Ren, Qingwen Zhang, Chong Liu
更新时间: 2018-11-24
摘要: To evaluate long-term effects of biochar addition and straw return (SR) on N2O fluxes in wheat-maize rotation system, a 2-year field experiment following a 7-year biochar addition and SR was investigated in an intensively managed agricultural soil in the North China Plain (NCP). Four treatments were included: 1) no biochar addition (CK); 2) biochar treatment with 4.5 t ha−1 yr−1 (C1); 3) biochar treatment with 9.0 t ha−1 yr−1 (C2); and 4) all the wheat/maize straw return (SR). The results showed the annual cumulative N2O emissions from C1 treatment were increased by 15.9–16.5%, while C2 treatment suppressed the annual cumulative N2O emissions by 22.8–26.3%. In comparison, straw return suppressed N2O emissions by 13.4–43.6% in the wheat season but increased N2O emissions remarkably by 45.3–53.9% in the maize season. Biochar addition enhanced the copies of AOA, AOB, nirK, nirS, and nosZ genes, while straw return decreased the copies of AOB, nirK, nirS, and nosZ genes at the high N2O emission period in the maize season. The production of N2O in the maize season was mainly driven by the AOB and nosZ genes, and by AOB gene in the wheat season. These results suggest that application of 9.0 t ha−1 yr−1 biochar is a more optimum agricultural strategy for reducing N2O emission in the wheat-maize system.
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13934. 题目: A novel hay-derived biochar for removal of tetracyclines in water
文章编号: N18112422
期刊: Bioresource Technology
作者: Hyun Min Jang, Eunsung Kan
更新时间: 2018-11-24
摘要: The biochars derived from alfalfa (AF) and bermudagrass (BG), the abundant grass hays to cows, were prepared, characterized and used for removal of tetracycline (TC) in water. The alfalfa-derived biochar (AF-BC) has exhibited outstanding TC adsorption capacity (372 mg/g), which was about 8-fold higher than that of bermudagrass-derived biochar (BG-BC). In addition, the TC adsorption capacity of AF-BC was comparable with those of the commercial activated carbons under the same conditions. The surface structure, chemistry and high ash contents of AF-BC suggested the hydrogen bonding, electrostatic interactions and surface complexation between AF-BC and TC. Furthermore, hydroxyapatite (HAP; Ca5(PO4)3OH) and calcite (CaCO3) on the surface of AF-BC may also contribute to adsorption of TC via surface complexation, hydrogen bonding and electrostatic interactions. The alkaline desorption-driven regeneration of TC-spent AF-BC led to effective adsorption-desorption for multiple cycles, which indicated AF-BC could be a cost-effective adsorbent for TC in water and wastewater.

13935. 题目: Effects of chlorination on the fluorescence of seawater: Pronounced changes of emission intensity and their relationships with the formation of disinfection byproducts
文章编号: N18112421
期刊: Chemosphere
作者: Massimiliano Fabbricino, Mingquan Yan, Gregory V. Korshin
更新时间: 2018-11-24
摘要: Chlorination of coastal (CS) and deep ocean (DO) seawater was accompanied by a prominent decrease (of up to 70%) of the intensity of its emission which was measured using a 315 nm excitation wavelength. Deconvolution of the emission spectra of CS and DO seawater showed that these spectra comprised three Gauss-shaped bands. The intensities of two of these bands decreased rapidly as the halogenation proceeded. For both DO and CS seawater, two stages of changes of their fluorescence were observed. The first stage in which the relative changes of the fluorescence intensity (ΔF/F) were between zero to 0.30 and 0.40 was not accompanied by the release of individual disinfection byproduct (DBP) species. For ΔF/F values above the corresponding thresholds, the relative changes of fluorescence intensity were well correlated with the concentrations of individual DBP species such as trihalomethanes and haloacetonitriles. R2 values for CHBr3, CHBr2Cl and CHBrCl2 formed in DO seawater were 0.83, 0.80 and 0.68, respectively while for CS seawater, the corresponding R2 values were 0.91, 0.93 and 0.92. The presented data demonstrate that the intrinsic chemistry of DBP formation and dissolved organic matter (DOM) halogenation in seawater can be well quantified based on the examination of changes of its fluorescence. This approach can also be employed for practical monitoring of changes of properties of marine DOM and generation of DBPs in desalination, marine aquaculture and other processes.
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13936. 题目: Ferrous Wheel Hypothesis: Abiotic nitrate incorporation into dissolved organic matter
文章编号: N18112420
期刊: Geochimica et Cosmochimica Acta
作者: Francisco Matus, Svenja Stock, Wolfram Eschenbach, Jens Dyckmans, Carolina Merino, Francisco Nájera, Moritz Köster, Yakov Kuzyakov, Michaela A. Dippold
更新时间: 2018-11-24
摘要: We evaluated the abiotic formation of dissolved organic nitrogen (DON) by the fast reaction of iron (Fe) with nitrate (NO3-) in the dissolved organic matter (DOM) of volcanic soils in a temperate rainforest (>5000 mm precipitation per year). During five days, the educts and products of abiotic reactions under anoxic conditions were measured in a microcosm experiment depending on the Fe and NO3- concentrations. A control zero-Fe was tested under sterile and anoxic conditions, but there was no chemical reaction with the nitrate. Using a novel technique of automated sample preparation for inorganic N (SPIN) followed by attached to a membrane inlet quadrupole mass spectrometry (MIMS), the 15N abundances and inorganic N concentrations were determined directly in aqueous solutions. The results were explained in the context of the Ferrous Wheel Hypothesis that states that the Fe(II) is utilized to reduce NO3- to nitrite (NO2-) that is incorporated in DOM. Fe(II) is regenerated from Fe(III) in anaerobic soil microsites. Here we tested one part of this hypothesis, the processes occurring in DOM (instead of soil organic matter). Using the SPIN-MIMS technique, we could overcome Ferrous Wheel Hypothesis criticism regarding possible Fe interference during NO3- analysis. The total recovery of 15N added as NO3- fluctuated between 63 and 101%, and the remaining 15N was measured as gaseous N2O. The 15N-labelled NO3- added decreased immediately after 15 min of incubation. After five days of incubation, approximately 25% of the labelled NO3- (e- acceptors) added was transformed to DON in the presence of a high amount of Fe(II) (e- donors). Small amounts of N2O and CO2 provided further evidence of NO3- reduction and DOM oxidation, respectively. From these results, we propose a new theoretical model that includes the Ferrous Wheel Hypothesis, where only the transformation of NO3- to DON was proven. The present results explain the high retention of NO3- in DOM from volcanic soils in ecosystems with high precipitation.
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13937. 题目: Assembling biochar with various layered double hydroxides for enhancement of phosphorus recovery
文章编号: N18112419
期刊: Journal of Hazardous Materials
作者: Fan Yang, Shuaishuai Zhang, Yuqing Sun, Daniel C.W. Tsang, Kui Cheng, Yong Sik Ok
更新时间: 2018-11-24
摘要: Highly efficient and cost-effective adsorbents for phosphate (P) recovery are the key to control eutrophication and recover phosphorus from waste streams to enhance food production. This study assembled corn stalk-derived biochar (BC) with various forms of layered double hydroxides (LDHs) (B-M-LDH) through simultaneous pyrolysis of waste biomass and metal (i.e., Zn/Al, Mg/Al, and Ni/Fe) hydroxide precipitates. Batch sorption experiments evaluated the kinetics and isotherms of phosphate adsorption as well as the influence of pH value and co-existing anions. Morphological characterization showed that crystalline LDH flakes were impregnated within the framework of fabricated B-M-LDH composites. Superior P adsorption capacity (152.1 mg (P) g−1) and fast Elovich kinetics (5925 mg g−1 h−1) could be achieved by the B-Zn/Al-LDH composite at pH 5. The P adsorption onto BC-LDHs was pH dependent and subjected to adverse influence of co-existing anions. Interlayer anion exchange and surface complexation were probably the predominant adsorption mechanisms at the studied phosphate concentration. Therefore, BC can be functionalized as mineral composites for enhancing P recovery and wastewater treatment.
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13938. 题目: Effect of gasification biochar application on soil quality: Trace metal behavior, microbial community, and soil dissolved organic matter
文章编号: N18112418
期刊: Journal of Hazardous Materials
作者: Xiao Yang, Ana Tsibart, Hyungseok Nam, Jin Hur, Ali El-Naggar, Filip M.G. Tack, Chi-Hwa Wang, Young Han Lee, Daniel C.W. Tsang, Yong Sik Ok
更新时间: 2018-11-24
摘要: Compared to pyrolysis biochar (PBC), gasification biochar (GBC) differs in both composition and surface functionalities due to the use of an oxidizing purging gas. This work compares the effect of using PBC and GBC as soil amendments on the soil properties, trace metal bioavailability, soil microbial activity, and soil dissolved organic matter (DOM). Biochar-driven reduction of bioavailable metals does not necessarily result in a positive impact on the soil microbial growth. The DOM in the soil was strongly related to the soil microbial activity, as revealed by the strong correlation between the soil dehydrogenase activity (DHA) and soil dissolved organic carbon (r = 0.957, p < 0.01). Three identified fluorescent components (C1, C2, C3) in the soil DOM were closely associated with the soil microbial activity, for instance, with a clear positive correlation between the soil DHA and C1 (r = 0.718, p < 0.05) and a significant negative correlation between the total bacterial fatty acid methyl ester content and C3 (r = -0.768, p < 0.05). The bioavailability of Cd and Zn is not only related to the pH and surface functionalities of the biochar, but also to its aromatic carbon and inorganic mineral composition. This study further demonstrates that a fluorescence excitation-emission matrix coupled with parallel factor analysis is a useful tool to monitor changes in the soil quality after application of biochar, which is greatly relevant to the soil biota.
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13939. 题目: Assessment of biochar and zero-valent iron for in-situ remediation of chromated copper arsenate contaminated soil
文章编号: N18112417
期刊: Science of The Total Environment
作者: Hanna Frick, Stacie Tardif, Ellen Kandeler, Peter E. Holm, Kristian K. Brandt
更新时间: 2018-11-24
摘要: Chromated copper arsenates (CCA) have been extensively used as wood impregnation agents in Europe and North America. Today, CCA contaminated sites remain abundant and pose environmental risks that need to be properly managed. Using a TRIAD approach that combined chemical, ecotoxicological and ecological assessment of soil quality, we investigated the abilities of biochar and zero-valent iron (ZVI) to remediate CCA contaminated soil in a microcosm experiment. Soil samples from a highly contaminated CCA site (1364, 1662 and 540 μg g−1 of As, Cu and Cr, respectively) were treated with two different biochars (fine and coarse particle size; 1% w w−1) and ZVI (5% w w−1), both as sole and as combined treatments, and incubated for 56 days at 15 °C. In general, bioavailable As (Asbio) and Cu (Cubio) determined by whole-cell bacterial bioreporters corresponded well to water-extractable As and Cu (Aswater and Cuwater). However, in biochar treatments, only Cubio and not Cuwater was significantly reduced. In contrast, under ZVI treatments only Cuwater and not Cubio was reduced, demonstrating the value of complementing analytical with bacterial bioreporter measurements to infer bioavailability of elements to soil microorganisms. The combined fine particle size biochar and ZVI treatment effectively reduced water extractable concentrations of Cr, Cu, and As on site by 45%, 45% and 43% respectively, and led to the highest ecological recovery of the soil bacterial community, as measured using the [3H]leucine incorporation technique. We conclude that the combined application of biochar and ZVI as soil amendments holds promise for in-situ stabilization of CCA contaminated sites.
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13940. 题目: Turn the potential greenhouse gases into biomass in harmful algal blooms waters: A microcosm study
文章编号: N18112416
期刊: Science of The Total Environment
作者: Hainan Ai, Yixi Qiu, Qiang He, Yixin He, Chun Yang, Li Kang, Huarui Luo, Wei Li, Yufeng Mao, Meijuan Hu, Hong Li
更新时间: 2018-11-24
摘要: Carbon sources are a critical requirement for the proliferation of algae and the occurrence of harmful algal blooms (HABs), but are often turned into methane (CH4) after the collapse of severe HABs. Here, we attempt to remove HABs, reduce algal-derived CH4 emissions, and repair the broken carbon biogeochemical cycle in aquatic systems using an integrated ecological approach including flocculation, capping, and submerged macrophyte induction, preliminary at a microcosm scale. This strategy sustainably reached 98% algal removal after 65 days of incubation and resulted in an aerobic microenvironment (ORP = +12 mv) at the sediment-water interface. The approach contributed to an approximate 60% decline in CH4 released from the aquatic environment into the atmosphere jointly through assimilation of mineralized organic carbon by submerged macrophytes, production of carbon dioxide (CO2) under aerobic conditions, and aerobic CH4 oxidation. Some of the CO2 produced in the aquatic phase contributed to inorganic carbon and formed the submerged macrophytes biomass. A combination of flocculation, capping, and submerged macrophyte incubation were significant contributors to altering the carbon budget and sealing nearly 99% of the carbon in the simulated ecosystem (the majority in sediment, followed by submerged macrophytes), providing a sustainable way to reuse algal-derived carbon and reduce CH4 emissions.
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