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13981. 题目: Differences in photochemistry between seawater and freshwater for two natural organic matter samples
文章编号: N18122211
期刊: Environmental Science: Processes Impacts
作者: Laura T. Stirchak, Kyle J. Moor, Kristopher McNeill, D. James Donaldson
更新时间: 2018-12-22
摘要: We report changes in the excitation and resolved fluorescence spectra, inferred triplet formation and singlet oxygen formation abilities of two different Natural Organic Matter samples (NOM) in seawater vs. freshwater or NaCl solution. In artificial seawater solution (but not in NaCl solution), the natural water-derived NOM samples Suwannee River Natural Organic Matter (SRNOM) and Nordic Reservoir Natural Organic Matter (NRNOM) display large enhancements in fluorescence intensity. Nearly identical spectra are seen when seawater is replaced by solutions of Mg2+ at its seawater concentration, consistent with magnesium binding to ligand sites of the natural organic matter giving rise to different photophysics. Fluorescence anisotropy measurements show a decrease in anisotropy of SRNOM and NRNOM in seawater, also consistent with Mg2+ binding. Different effects of Mg2+ are seen when the different NOM samples are illuminated: NRNOM exhibits increased formation of its triplet state and also quenching of its triplet by oxygen, compared to its photochemistry in the absence of Mg2+, while SRNOM exhibits a reduction in triplet formation in the presence of Mg2+. These observations imply that the photochemistry of NOM in seawater may be very different from what is expected based on freshwater or NaCl solution measurements.
图文摘要:

13982. 题目: Effect of waterlogging on soil biochemical properties and organic matter quality in different salt marsh systems
文章编号: N18122210
期刊: Geoderma
作者: Chiara Ferronato, Sara Marinari, Ornella Francioso, Diana Bello, Carmen Trasar-Cepeda, Livia Vittori Antisari
更新时间: 2018-12-22
摘要: This study investigated the effects of hydroperiod on soil organic matter quality in three different salt marshes in the Baiona lagoon (N Italy) representing terrestrial, intertidal and subaqueous ecosystems in the area. The study specifically aimed to gain some insight into how soil waterlogging (hydroperiod) affects the chemical and biological properties of soils as well as the quality and structure of the soil organic matter (SOM). Total contents of selected nutrients, total organic carbon and carbon stable isotope (δ13C) were measured in all soil profiles. The results of these analyses enabled us to define the different origin of the SOM by discriminating between terrestrial and aquatic SOM sources. The findings also show that accumulation of nutrients and SOM is significantly magnified in intertidal systems, in which pedoturbation effects induced by water movements are particularly strong. In addition, DRIFT spectra of humic acids revealed the changes in the main functional groups in relation to increased waterlogging, highlighting the lower aromaticity and complexity in subaqueous soils (SASs), which is possibly due to the effect of the soil water saturation on the chemical and biological SOM transformation processes. Microbial biomass carbon (MBC), microbial quotient (Qmic) and the activities of some soil enzymes were measured to estimate soil metabolic activity in the systems and to evaluate how the microbial pool contributes to transforming the SOM. In all systems, the enzymatic activities were generally higher in subsurface horizons than in the surface horizon. This unexpected behaviour can be explained by the combined effect of water movement, erosion processes and preservation of SOM under anaerobic conditions. This study represents an attempt to investigate and understand the ongoing degradation processes in salt marsh ecosystems. The findings emphasize the strong influence of water flow and erosional processes associated with soil waterlogging on chemical and biological reactions in intertidal and subaqueous systems.

13983. 题目: Soil parent material and stand development stage effects on labile soil C and N pools in Chinese fir plantations
文章编号: N18122209
期刊: Geoderma
作者: Yun Zhang, Mulualem Tigabu, Zhigang Yi, Huitong Li, Zheng Zhuang, Zhen Yang, Xiangqing Ma
更新时间: 2018-12-22
摘要: Plantation development stage (forest age sequence) influences environmental conditions and litter inputs, which can modify labile C and N pools. Changes in labile C and N pools during stand development could vary considerably with soil parent material. However, empirical evidence is scarce regarding the extent of interactive effects between parent material and stand development stage on labile C and N pools in plantations of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), the dominant plantation tree in southern China. We examined the concentrations of soil labile C and N (dissolved organic carbon, DOC, dissolved organic nitrogen, DON, dissolved inorganic nitrogen, DIN, microbial biomass carbon, Cmic, microbial biomass nitrogen, Nmic) and basic soil properties within a soil depth of 100 cm for three stand development stages (young, middle-aged and mature) of Chinese fir plantations grown on soils derived from granite or siltstone. The parent material influenced the responses of the DON, DIN and Nmic pools to stand development stage, whereas no interaction effect of parent material and stand on the Cmic and DOC pools was observed. The parent material had a clear effect on the standing pools of labile C and N. Siltstone soils tended to have greater pool sizes of DOC, DON, DIN, and Nmic and greater ratios of Cmic/total carbon (TC) and Nmic/total nitrogen (TN). The stand development stage did not affect the DOC, Cmic and Cmic/TC ratio. The mineral N and Nmic pools increased significantly and the DON and DON/TN ratio declined sharply from young to middle-aged stands in both soil type. The changes in the DON, DIN and Nmic pools and the Nmic/TN ratio from middle-aged to mature stands depend on the parent material. The concentrations of DOC, DON, DIN, Cmic and Nmic were positively correlated with multiple soil parameters, such as the TC, TN, C/N ratio, water-stable aggregates (WSA), and water content, but negatively correlated with the bulk density (BD). DOC, DON, Cmic and Nmic significantly decreased with soil depth, but the extent of the decrease in DOC and DON was greater in course-textured granite soils. Overall, the turnover rates of the labile C pools are higher in the siltstone soils where internal N cycling during a traditional rotation ~25 years maintain the supply of mineral N and improve N incorporation into microbial biomass. These results highlight the need to identify soil physicochemical properties before afforestation. The rotation length and N fertilizer application in Chinese fir plantations should be adjusted based on the soil parent material.

13984. 题目: Soil carbon sequestration to depth in response to long-term phosphorus fertilization of grazed pasture
文章编号: N18122208
期刊: Geoderma
作者: Elizabeth C. Coonan, Alan E. Richardson, Clive A. Kirkby, John A. Kirkegaard, Martin R. Amidy, Richard J. Simpson, Craig L. Strong
更新时间: 2018-12-22
摘要: The impact of phosphorus (P) fertilizer application on the sequestration of soil organic carbon (C) was investigated in an acidic permanent pasture soil grazed by sheep. Data were collected after 20 years of P fertilization (average 19 kg P ha−1 year−1) compared to a non-P fertilized control, on a P deficient soil. The high P treatment had higher productivity and stocking rate (hereafter termed fertilization treatment). Soils to a depth of 110 cm were analysed for soil bulk density, whole soil C and nitrogen (N), and for C, N, P and sulphur (S) that was associated with a soil pool of fine fraction C (FFC). Fertilization and higher stocking rate had no effect on soil pH but led to a decrease in soil bulk density to depth, and an increase in total soil C that was associated with an increase in both the whole soil C (WSC) and the FFC throughout much of the soil profile. The increase in soil C was evident in both the C concentration (mg C kg−1 soil) and C stocks (Mg C ha−1) to a depth of at least 60 cm, with the largest difference between fertilizer treatments occurring in the top 10 cm soil layer. In the 0–10 cm layer, P fertilization increased soil organic matter (SOM) by ~1% from 3% SOM in the unfertilized treatment to 4% SOM in the fertilized treatment. Over the top 60 cm of soil profile, P fertilization increased total C stock by 12 Mg C ha−1, with 92% of the C stock associated with the FFC. The higher soil C in the fertilized treatment was also correlated with a concomitant increase in N, P and S content in the FFC pool (R2 = 0.97, 0.89 to 0.82 for N, P and S, respectively), whereas in the unfertilized treatment nutrient correlations with C in the FFS were observed for N and S only. Although C:N, C:P and C:S nutrient mass ratios in the FFC pool differed markedly with soil depth, no significant difference in nutrient ratios were observed due to fertilizer treatment for any of the nutrients. Collectively our data indicate that sustained P input to a texture contrast pasture soil (Yellow Chromosol) and its associated increase in stocking rate and productivity in a temperate climate had significant long-term benefit for C sequestration and accumulation of soil organic matter (SOM) throughout the soil profile.

13985. 题目: Effect of bentonite-humic acid application on the improvement of soil structure and maize yield in a sandy soil of a semi-arid region
文章编号: N18122207
期刊: Geoderma
作者: Lei Zhou, Carlos M. Monreal, Shengtao Xu, Neil B. McLaughlin, Huaying Zhang, Guocheng Hao, Jinghui Liu
更新时间: 2018-12-22
摘要: Sandy soils have poor soil structure, low water retention and low crop productivity. A bentonite-humic acid (B-HA) mixture was applied at a single rate of 30 Mg ha−1 to a sandy degraded soil of China for improving soil physical properties and hydric regime, and productivity of maize (Zea mays L.). Measurements of soil aggregate distribution, soil bulk density (BD), soil water storage (SWS), and yield of maize and associated water use efficiency (WUE) helped to evaluate the effect of the B-HA 1 to 7 years after B-HA application. The addition of B-HA increased soil health by improving soil structure thereby facilitating the rapid formation of macro-aggregates, decreasing soil BD and increasing SWS in the top 100 cm. B-HA addition also increased maize growth and grain yield and WUE by 50%, 5 years after B-HA application. Linear regression and Principal Component analysis indicated that three macro-aggregate fractions and SWS were highly correlated with maize biomass and grain yield. Improvement of soil structure and hydric regime significantly increased maize grain and biomass yield and WUE. The addition of B-HA to sandy soil appears to be an appropriate technology for rapidly reclaiming a degraded soil in large areas of sandy land in semi-arid regions of the world.

13986. 题目: Organic carbon content controls the severity of water repellency and the critical moisture level across New Zealand pasture soils
文章编号: N18122206
期刊: Geoderma
作者: Cecilie Hermansen, Per Moldrup, Karin Müller, Peter Weber Jensen, Carlo van den Dijssel, Paramsothy Jeyakumar, Lis W. de Jonge
更新时间: 2018-12-22
摘要: Organic matter can render soil hydrophobic and cause soil water repellency (SWR) which has large implications for agriculture. Consequences such as fingered flow, uneven wetting patterns, and increased overland flow reduce irrigation efficiency and plant nutrient availability. The phenomenon of SWR is a transient soil property depending, inter alia, on soil water content (w). Soil can exhibit SWR from oven-dry w until the critical w where it again becomes fully wettable (wNON). The total SWR can be obtained from the nonlinear SWR-w relationship as the integrated trapezoidal area under the SWR-w curve (SWRAREA). We analyzed 78 soil samples, representing five dominant soil orders in the South Island of New Zealand. The soils had a large range in clay (0.000–0.520 kg kg−1) and organic carbon (OC) content (0.021–0.217 kg kg−1). The degree of SWR was measured on soils at air-dry conditions (SWRAD) and after heat-pretreatment at 60 (SWR60) and 105°C (SWR105). Further, SWR was measured in small w increments above air-dry w until wNON was reached. The SWR-w curves were either unimodal or bimodal, or no SWR occurred. SWRAREA ranged from 0.16 to 26.82 mN m−1 kg kg−1. Among the five soil orders tested, the Podzols exhibited the highest severity in SWR, whereas the Semiarid soils were the least hydrophobic soils. In conclusion, OC was the main factor for controlling the severity of SWR. Though, pH also had minor effects on SWR. Further, an upper limit critical water content was derived from the simple relationship between the wNON and OC, which could be applied to improve irrigation practices of pastoral soils. However, there is a need for further testing on different soils and land uses.

13987. 题目: Effects of composting and carbon based materials on carbon and nitrogen loss in the arable land utilization of cow manure and corn stalks
文章编号: N18122205
期刊: Journal of Environmental Management
作者: Ruixue Chang, Ying Yao, Wenchao Cao, Jue Wang, Xuan Wang, Qing Chen
更新时间: 2018-12-22
摘要: Recycling organic wastes to arable land as fertilizers has been recognized as a sustainable utilization to reduce environmental pollution. Techniques used for the treatment of organic wastes determine their nutrient contents and thus fertilizer efficiency for agricultural applications. The current study investigated the influences of composting and carbon based materials (biochar and woody peat), on carbon and nitrogen loss in the process of agricultural wastes utilization in the soil batch experiments. The results indicated composting process significantly strengthened the organic matter mineralization, increased the carbon loss rates from 33.46-38.96% to 60.54–86.15% and the nitrogen loss rates from 5.01-22.22% to 48.64–58.16%, dominant lost as carbon dioxide (CO2) and ammonia (NH3) emissions. Addition of carbon based materials could effectively reduce the carbon and nitrogen loss during both composting and soil incubation process. When the composted organic wastes were used in the soil batch experiments, woody peat was more effective to reduce nitrogen loss, while biochar was more effective to control carbon loss. When organic wastes were directly fertilized to soil, biochar could effectively reduce nitrogen loss. These results suggested that fertilizing raw agricultural wastes to with carbon based materials could reduce carbon and nitrogen losses, and increased the nutrient bioavailability in soil in comparison with their farmland application after composting.

13988. 题目: Graphene Oxide Quantum Dots Stimulate Indigenous Bacteria to Remove Oil Contamination
文章编号: N18122204
期刊: Journal of Hazardous Materials
作者: Li Mu, Qixing Zhou, Yujie Zhao, Xiaowei Liu, Xiangang Hu
更新时间: 2018-12-22
摘要: Oil spills occur frequently worldwide, resulting in severe damage to water and to human health. Polycyclic aromatic hydrocarbons (PAHs) are the primary toxic components in oil contamination. PAH-degrading microbes have attracted significant attention, but difficulty in their selection and proliferation limits their applications. Graphene oxide quantum dots (GOQDs) improve the proliferation of an indigenous PAH-degrading strain, Bacillus cereus, more effectively than large graphene oxide flakes. Bacillus cereus can metabolize a variety of xenobiotic aromatic compounds as carbon sources and is used in bioremediation. GOQDs contain a variety of aromatic hydrocarbon structures, explaining why the bacteria achieve strong tolerance to PAHs. GOQD-activated cytokinesis increases the secretion of substances important for biofilm formation (extracellular polymeric substances), which further accelerates PAH removal. Proteomic analysis reveals the molecular mechanisms underlying GOQD-induced microbial proliferation. GOQDs induce the overexpression of microbial divisomal proteins associated with division initiation, DNA replication and peptidoglycan hydrolysis/synthesis. Importantly, PAH removal mediated by GOQD-treated Bacillus cereus does not require the addition of GOQDs. The effects of GOQDs on a strain persist for at least 20 generations, suggesting their possible use in low-cost applications. This work proposes a strategy to remove oil contamination using an indigenous bacterial system enhanced by nanomaterials.
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13989. 题目: Fouling formation in membrane contactors for methane recovery from anaerobic effluents
文章编号: N18122203
期刊: Journal of Membrane Science
作者: Wichitpan Rongwong, Kunli Goh, G.S.M.D.P. Sethunga, Tae-Hyun Bae
更新时间: 2018-12-22
摘要: Fouling in membrane contactors for recovery of dissolved methane (CH4) was investigated in this work. Two types of effluents from anaerobic membrane bioreactor (AnMBR) and upflow anaerobic sludge blanket (UASB) were tested under a continuous operational mode. Due to the higher fouling propensity of the UASB effluent, membrane fouling was more drastic, leading to a greater decline in the CH4 desorption flux with respect to the operational time. Also, the flux was observed to be influenced by the gas-liquid contact time and declined more severely with increasing liquid velocity. Membrane characterization revealed cake layer formation as the source of membrane fouling while foulants characterization indicated that the majority of the foulants were protein-like-substances with fluorescence spectra showing signals close to that of extracellular polymeric substances. On this basis, a mass transfer analysis was performed to understand the fouling resistance exerted by the cake layer and identify a parameter which best described the fouling mechanism. It was found that cake thickness can be used to express the change in fouling resistance in the case of the AnMBR effluent, while cake porosity was a better parameter in the case of the UASB effluent.

13990. 题目: Biological sources of sedimentary organic matter in Neoproterozoic–Lower Cambrian shales in the Sichuan Basin (SW China): Evidence from biomarkers and microfossils
文章编号: N18122202
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Ning Wang, Meijun Li, Haitao Hong, Daofu Song, Xingwang Tian, Peng Liu, Ronghui Fang, Guo Chen, Maolin Wang
更新时间: 2018-12-22
摘要: Study of the occurrence and formation of sedimentary organic matter in the Sichuan Basin, southern China, provides valuable insights into the biological sources and compositions of Neoproterozoic to Lower Cambrian shales. Rock samples from two sets of shales in the Sichuan Basin and adjacent areas, including the Ediacaran Doushantuo shale and the Lower Cambrian Qiongzhusi shale in the Gaoshiti-Moxi and Ziyang-Weiyuan areas were collected and geochemically analyzed in this study.The distribution of biomarkers, stable carbon isotope compositions and microfossil characteristics reveal that eukaryotic algae including chlorophytes, pelagophyceae, dinoflagellates, diatoms (or their ancestors) and sponges proliferated widely during the Late Neoproterozoic to Early Cambrian in the Sichuan Basin. Cyanobacteria, some α-Proteobacteria, rhizobiales and aerobic methanotrophs also made a contribution to organic matter in the studied shales. Aerobic methanotrophs that utilize 13C-depleted substrates such as CH4 as carbon sources may have been the cause of anomalous 13C-depleted kerogen in the study area.

13991. 题目: Effect of temperature, pH and total organic carbon variations on microbial turnover of 13C315N-glyphosate in agricultural soil
文章编号: N18122201
期刊: Science of The Total Environment
作者: Angelica M. Muskus, Martin Krauss, Anja Miltner, Ute Hamer, Karolina M. Nowak
更新时间: 2018-12-22
摘要: Glyphosate is the best-selling and the most-used broad-spectrum herbicide worldwide. Microbial conversion of glyphosate to CO2 and biogenic non-extractable residues (bioNER) leads to its complete degradation. The degradation of glyphosate may vary in different soils and it depends on environmental conditions and soil properties. To date, the influence of temperature, soil pH and total organic carbon (TOC) on microbial conversion of glyphosate to bioNER has not been investigated yet. The pH or TOC of an agricultural original soil (pH 6.6, TOC 2.1%) was modified using sulfuric acid or farmyard manure (FYM), respectively. Each treatment: original (I), 3% TOC (II), 4% TOC (III), pH 6.0 (IV) and pH 5.5 (V) was amended with 13C315N-glyphosate and incubated at 10 °C, 20 °C and 30 °C for 39 days. The temperature was the main factor controlling the mineralization and the extractable 13C315N-glyphosate, whereas higher TOC content and lower pH resulted in enhanced formation of 13C-bioNER. After 39 days the cumulative mineralization of 13C-glyphosate was in the range of 12–22% (10 °C), 37–47% (20 °C) and 43–54% (30 °C). Extractable residues of 13C-glyphosate were in the range of 10–21% (10 °C) and 4–10% (20 °C and 30 °C); whereas those of 15N-glyphosate were as follows 20–32% (10 °C) and 12–25% (20 °C and 30 °C). The 13C-NER comprised about 53–69% of 13C-mass balance in soils incubated at 10 °C, but 40–50% in soils incubated at 20 °C and 30 °C. The 15N-NER were higher than the 13C-NER and varied between 62% and 74% at 10 °C, between 53% and 81% at 20 °C and 30 °C. A major formation of 13C-bioNER (72–88% of 13C-NER) at 20 °C and 30 °C was noted in soil amended with FYM. An increased formation of 15N-bioNER (14–17% of 15N-NER) was also observed in FYM-amended soil. The xenobiotic 15N-NER had a major share within the 15N-NER and thus need to be considered when assessing the environmental risk of glyphosate-NER.
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13992. 题目: Al/Fe mineral controls on soil organic carbon stock across Tibetan alpine grasslands
文章编号: N18122106
期刊: Journal of Geophysical Research: Biogeosciences
作者: Kai Fang, Shuqi Qin, Leiyi Chen, Qiwen Zhang, Yuanhe Yang
更新时间: 2018-12-21
摘要: Adequate understanding of the controlling factors of soil carbon (C) stock is crucial for improving the predictability of Earth System Models in exploring terrestrial C‐climate feedback. Current studies, however, mainly focus on climatic and edaphic variables, and rarely explore the effects of mineral protection in regulating soil organic C (SOC) stock over broad geographic scale. Particularly, the relative importance of mineral protection compared with other factors is unclear. Based on large‐scale soil inventory, here we filled this knowledge gap by exploring the effects of Al/Fe‐(hydr) oxides on SOC and three C fractions across Tibetan alpine grasslands via linear regression, partial correlation and variance partitioning analyses, and also comparing the degree of mineral protection in alpine grasslands with other ecosystems. Our results showed that SOC and C fractions across Tibetan alpine grasslands were regulated by Al/Fe‐(hydr) oxides, with the incorporation of mineral variables increasing the explained variations by 10.1% for SOC content, 13.4% for coarse particulate organic matter, 12.6% for microaggregate associated C, and 21.9% for silt and clay associated C. Moreover, the contribution of mineral effects exceeded that of climatic and edaphic factors, particularly in the silt and clay associated C fraction. In addition, about 15.8±12.0% of SOC pools was associated with Fe, which was equal or even higher than temperate and tropical‐subtropical ecosystems. Taken together, these results demonstrate the significant role of Al/Fe minerals in the stabilization of SOC across Tibetan alpine grasslands, highlighting the importance of incorporating C‐mineral interactions into ESMs for better understanding the terrestrial C‐climate feedback.

13993. 题目: The influence of sediment‐derived dissolved organic matter in the Vistula River Estuary/Gulf of Gdansk
文章编号: N18122105
期刊: Journal of Geophysical Research: Biogeosciences
作者: Heather E. Reader, Franziska Thoms, Maren Voss, Colin A. Stedmon
更新时间: 2018-12-21
摘要: Dissolved organic matter (DOM) concentrations in sediment porewaters are often orders of magnitude higher than in the overlying water column resulting in a diffusive flux of DOM from sediments. The intensity and fate of this DOM flux is poorly understood. The Gulf of Gdansk in the Southern Baltic Sea is dominated by the Vistula River, one of the largest and most anthropogenically impacted rivers in the Baltic Sea catchment. The sediment characteristics of the region are varied, from mixed sandy conditions near shore to mud sediments in the Gdansk Deep. We investigated the significance of sediment‐derived DOM in the Gulf of Gdansk in comparison to that supplied by the river. Sediment‐derived DOM in the region was found to have an organic matter fluorescence signature distinct from the DOM in the water column. The visible wavelength fluorescence could be used to distinguish organic matter from near shore sediments influenced by riverine sources and organic matter from deeper offshore sediments, influenced by more pelagic sources. UVA wavelength fluorescence dominated the sediment flux but was rapidly removed in bottom waters suggesting that it may contribute to bottom water oxygen consumption. While there is potential for DOM fluxes from sediments in the Gulf of Gdansk, the high background pelagic concentration of DOM in these waters and the much stronger influence of the Vistula River can mask the contributions from sediments.

13994. 题目: The microbial network in naturally fertile paddy soil possibly facilitates functional recruitment in the rice mature stage
文章编号: N18122104
期刊: Applied Soil Ecology
作者: Xuesong Luo, Shun Han, Xiaoqian Fu, Xiang Li, Li Wang, Shaobing Peng, Wenli Chen, Qiaoyun Huang
更新时间: 2018-12-21
摘要: How agriculture practice, especially the nitrogen fertilization, influences different paddy soil microbial ecosystems remains unclear. The bacterial communities in two paddy fields, which were distinguished by the natural fertility level, were utilized in this study. Each field held two control plots and two nitrogen-fertilized ones. The microbial communities mainly differed in their relative abundances of Proteobacteria and Chloroflexi between the two fields. However, they were very similar in the α-diversity and enzymatic functions, as well as their resistances indexes in response to the nitrogen fertilizers. Redundancy analysis indicated that phosphorus, nitrogen and potassium contents significantly explained the variability of the communities in the two fields total potassium (TK) plus nitrogen level and TK alone significantly explained the variation of the microbial communities in the high yield field and the low yield, respectively. Network analysis data showed that the microbial community in the high-yield field possessed a higher connectivity, which might facilitate recruiting more microbes that were predicted to drive organic matter decomposition, sulfate/iron reduction, nitrogen retention, and methane oxidation at the mature stage. The use of nitrogen fertilizer in the low yield field would help to recruit microbial functions similar to those in the high-yield at the stage. This ecological process possibly stimulated nutrient availability for rice production in the present case.
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13995. 题目: The influence of biochar and compost mixtures, water content, and gas flow rate, on the continuous adsorption of methane in a fixed bed column
文章编号: N18122103
期刊: Journal of Environmental Management
作者: Helen La, J. Patrick A. Hettiaratchi, Gopal Achari
更新时间: 2018-12-21
摘要: Biofiltration is an excellent alternative for the treatment of diffuse emissions of methane (CH4) that cannot be treated by physical/chemical means or recovered for energy. Despite the advances on CH4 biological treatment technologies, they are limited by the low aqueous solubility of CH4 into the biofilm where CH4 mineralization occurs. In this study, the CH4 adsorption kinetics, adsorption capacity and transport behavior of CH4 was studied in batch experiments and in a fixed-bed column by varying the biochar and compost mixtures under 5-levels, 3 different water contents (dry, 15% and 30% water holding capacity), and 2 inlet flow rates. Experimental results were formally tested using analysis of variance (ANOVA) in order to draw objective conclusions based on statistical inference. As CH4 biofiltration requires water addition to maintain microbial activity, these results indicate adsorption capacity is not lost with water addition if biochar content is the dominant packing material. The Langmuir isotherm described the data best (R2 = 0.99). Maximum adsorption capacity by monolayer adsorption, or qmax, is relatively similar with or without the addition of water as long as the biochar component is the dominant material at 3.5 mg CH4/g medium for a 7:1 biochar: compost, v/v mixture. Empirical regression models for qo, kTh, (Thomas model) and τ and KYN (Yoon-Nelson model) were developed for the break through curves of CH4. The current work demonstrates the applicability of utilizing biochar, a relatively inexpensive adsorbent, can compensate for the low solubility of CH4 and overcome the rate-limiting step of mass transfer from the gas phase and into the methanotrophic biofilm. Further, biochar may be a reliable back-up system for CH4 storage especially for fluctuating inlet loads that may be encountered in industrial applications adsorbing up to 13 mg CH4/g biochar under dry conditions.
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13996. 题目: Effect of water washing pretreatment on property and adsorption capacity of macroalgae-derived biochar
文章编号: N18122102
期刊: Journal of Environmental Management
作者: Patrick Boakye, Hai Nguyen Tran, Dae Sung Lee, Seung Han Woo
更新时间: 2018-12-21
摘要: The effects of water washing pretreatment process on the property and adsorption capacity of biochar were investigated at different biochar/water ratios from 1:5 to 1:100 (w/v). Saccharina japonica macroalgae-derived biochars (B300, B450, and B600) were prepared at 300 °C, 450 °C, and 600 °C, respectively. The optimal biochar/water ratio was obtained at 1:10. The results indicated that the washing pretreatment can contribute to dramatically increasing the specific surface area of biochars, but slightly increasing their porosity. The washed biochars were carbonaceous microporous materials (67–80% micropore volume), with their specific surface area and porosity being B600 (543 m2/g and 86%), B450 (521 m2/g and 75%), and B300 (188 m2/g and 80%), respectively. The unwashed biochars exhibited a significantly higher ash content (59%–65%) than washed biochars (26%–35%). Equilibrium adsorption study demonstrated that the Langmuir maximum adsorption capacity (Qomax) of crystal violet cationic dye decreased in the following order: unwashed-B450 (1719 mg/g) > washed-B450 (1277 mg/g) > commercial activated carbon (492 mg/g). The washing pretreatment can remove solute-inorganic minerals to prevent their release from biochar during the dye adsorption. The washed biochar with its excellent adsorption capacity can serve as a highly sustainable and industrially viable adsorbent for the removal of cationic dyes from waste bodies.

13997. 题目: Thiothrix eikelboomii Interferes Oxygen Transfer in Activated Sludge
文章编号: N18122101
期刊: Water Research
作者: Xianwei Wu, Ju Huang, Zichuan Lu, Gaofeng Chen, Jianmin Wang, Guoqiang Liu
更新时间: 2018-12-21
摘要: This study revealed that, Thiothrix eikelboomii, a well-known filamentous bacterium that causes sludge bulking, could also interfere oxygen transfer during wastewater treatment. The volumetric oxygen transfer coefficient (KLa) in filamentous-bulking sludge (FBS) was found to be 43% lower than that in floc-forming sludge (FFS) at similar biomass concentrations, partially because the filamentous bacteria had increased the sludge apparent viscosity. The KLa value for FBS, however, was still significantly lower than that for FFS even if both sludges had similar apparent viscosity. Numerous tiny and free-swimming filaments were observed to attach on the air bubble surface, presumably reducing the liquid film renewal and increasing the liquid film thickness. Moreover, the filaments were co-coated with extracellular polymeric substances of protein and polysaccharide, which could make them performing like “amphiphilic molecules” of surfactants to hinder oxygen transfer. Therefore, the particular surface property of filaments and their interaction with air bubbles could also impact oxygen transfer. Thiothrix eikelboomii was identified to be the responsible filamentous bacterium that lowered the KLa value, while other filamentous bacteria with short filaments did not interfere oxygen transfer. This study implies that controlling sludge bulking benefits not only sludge settling but also oxygen transfer.
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13998. 题目: Organic carbon quality, composition of main microbial groups, enzyme activities, and temperature sensitivity of soil respiration of an acid paddy soil treated with biochar
文章编号: N18122023
期刊: Biology and Fertility of Soils
作者: Junhui Chen, De Chen, Qiufang Xu, Jeffry J. Fuhrmann, Lianqing Li, Genxing Pan, Yongfu Li, Hua Qin, Chenfei Liang, Xuan Sun
更新时间: 2018-12-20
摘要: The role of soil organic C (SOC) quality affecting microbial community composition and function under biochar application is poorly understood. We investigated the relationship between the pool size and chemical composition of SOC; composition of main microbial groups; enzyme activities involved in C, N, and P cycling; and soil respiration in a rice paddy amended with biochar for 20 months in a laboratory experiment at 15, 25, and 35 °C. Soil labile and recalcitrant organic C pools were determined by a two-step sulfuric acid (H2SO4) hydrolysis method. The chemical composition of SOC was determined with 13C-nuclear magnetic resonance spectroscopy. The biochar amendment at 20 and 40 t ha−1 significantly decreased the soil labile C pool I (extracted by 5 N H2SO4), alkyl, and carbonyl C contents and increased the recalcitrant C pool (acid-resistant) and aromatic C contents and the aromatic C to O-alkyl C ratio. The phospholipid-fatty acid concentrations and soil enzyme activities were unchanged by biochar application at 10 and 20 t ha−1, but both were increased at 40 t ha−1. Biochar increased the ratio of gram-positive (G+) to gram-negative (G−) bacteria and decreased that of fungi to bacteria. The recalcitrant C pool and aromatic C contents were positively correlated to the G+ bacteria abundance and were important factors in shaping composition of the main microbial groups and improving enzyme activities. Biochar application at 40 t ha−1 lowered soil respiration rates at 15 and 25 °C by decreasing labile C pool and increasing C recalcitrancy while increased temperature sensitivities of soil respiration at 25/15 °C and 35/25 °C by stimulating microbial abundance and enzyme activities. Together, our results suggest that biochar soil amendment shifted microbial community composition and function through influencing the composition of SOC.

13999. 题目: Mercury adsorption to aged biochar and its management in China
文章编号: N18122022
期刊: Environmental Science and Pollution Research
作者: Shiqiu Zhang, Xue Yang, Meiting Ju, Le Liu, Kui Zheng
更新时间: 2018-12-20
摘要: Biochar is frequently applied for the reduction of mercury (Hg) migration in soil; however, most of the studies only focused on the adsorption capacity evaluation of fresh biochar. We investigated the Hg adsorption capacities of biochar prepared from wheat straw, corn straw, and sunflower seed shells. Biochar aging was simulated via natural aging, high-temperature aging, and freeze-thaw aging. The adsorption capacities of all the aged biochar were increased, and wheat straw biochar and seed shells biochar treated with high-temperature aging (wBC-Ha500 and sBC-Ha600) and corn straw biochar treated with freeze-thaw aging (cBC-Fta500) showed an observable improvement on the equilibrium adsorption amounts. The kinetics of the fresh biochar samples fitted the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, while the kinetics of the aged biochar samples fitted the pseudo-second-order kinetic model. Biochar adsorption capacity increased with higher initial concentrations and increasing temperatures. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) spectra, cation-exchange capacity (CEC), surface area (SA), zeta potential, and X-ray photoelectron spectroscopy (XPS) showed that the aging mechanism consisted of hydroxylation and carboxylation caused by the functional groups on the biochar surface. According to the different climatic zones in China, wheat straw biochar and seed shell biochar are suitable for the tropical zone and the subtropical zone, while corn straw biochar is more suitable for the cold and the mid-temperate zones.

14000. 题目: Size Dependence of the Physical Characteristics of Particles Containing Refractory Black Carbon in Diesel Vehicle Exhaust
文章编号: N18122021
期刊: Environmental Science & Technology
作者: Chong Han, Shao-Meng Li, Peter Liu, Patrick Lee
更新时间: 2018-12-20
摘要: The number and mass size distributions of refractory black carbon (rBC) cores in particles emitted from a diesel vehicle were investigated as a function of particle mobility diameter (dmob) using a single particle soot photometer (SP2) and a differential mobility analyzer (DMA). The thickness and mass of coatings on the rBC cores were characterized. On the basis of the SP2 and DMA results, the physical properties of particles containing rBC, including effective density (ρeff), mass-mobility scaling exponent (Dm), dynamic shape factor (χ), and mass absorption cross section (MAC), were derived as a function of dmob. At each dmob, the count median diameter (CMD) of the rBC cores was essentially the same as their mass median diameter (MMD), which increased linearly with dmob. The mass of the rBC cores was proportional to the cubic of their dmob. However, coating thickness on rBC cores remained unchanged with dmob, with an average thickness of 28.72 ± 4.81 nm. For particles containing rBC, ρeff decreased and χ increased with dmob. The Dm of particles containing rBC was calculated to be 2.09. At 355 and 532 nm wavelengths, the MAC of the diesel particles containing rBC was inversely dependent on dmob.
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