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26021. 题目: Efficacy of vermitechnology integration with Upflow Anaerobic Sludge Blanket (UASB) and activated sludge for metal stabilization: A compliance study on fractionation and biosorption
文章编号: N19021607
期刊: Journal of Environmental Management
作者: Kaling Taki, Anindita Gogoi, Payal Mazumder, Satya Sunder Bhattacharya, Manish Kumar
更新时间: 2019-02-16
摘要: Efficacy of vermi-transformation for metal partitioning and transformation from Upflow Anaerobic Sludge Blanket (UASB) and Activated Sludge (AS) was investigated. Sludge samples were mixed with cow dung (CD) in two combinations (1:1 (UASB/AS:CD)) & (2:1(UASB/AS: CD)). Fractionation study revealed that Zn, Cd & Pb were associated with reducible fractions, and Cr, Cu with oxidizable fractions. Higher removal efficiency for 1:1 (UASB/AS: CD) combination over 2:1 (UASB/AS: CD) implies the non-significant contribution of cow dung during the metal stabilization process. After vermi-remediation, maximum metal removal was achieved at 1:1 ratio than 2:1 in AS. In UASB, 1:1 ratio worked better for Cr, Zn & Cd, whereas for Cu & Zn 2:1 ratio resulted in efficient removal. Overall for both AS and UASB, efficiency was found to be higher in 1:1 treatment ratio. The value of Kd (Bio sorption) was highest in Cu followed by Cr, which indicates the closer association with the metal bound organic matter (R2 ≥ 0.99). Based on the compliance study between two estimated sorption coefficients Kd (Biosorption & Fractions), vermi-remediation was found to be effective for AS than UASB. Therefore, the obtained results clearly validate the feasibility of integration of vermi-remediation as a potential promising ecological techniques for removing metal contaminant from the wastewater. Further research is required to study the decontamination of emerging contaminants with such integrated technology, which have physico-chemical properties different than metal ions.
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26022. 题目: Construction of magnetic lignin-based adsorbent and its adsorption properties for dyes
文章编号: N19021606
期刊: Journal of Hazardous Materials
作者: Chenglong Jiang, Xiaohong Wang, Demeng Qin, Wenxin Da, Bingxia Hou, Chen Hao, Jingbo Wu
更新时间: 2019-02-16
摘要: The magnetic lignin-based adsorbent (Fe3O4/C-ACLS) has been successfully prepared and applied to adsorbing azo dyes Congo red, Titan yellow and Eriochrome blue black R. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray powder diffraction (XRD), vibration sample magnetometer (VSM), Raman spectroscopy and elemental analysis. In the process of adsorption, five kinds of influencing factors and recycling regeneration were discussed, and the adsorption mechanisms such as kinetics, isotherm, thermodynamics were explored. The results show that Fe3O4/C-ACLS can remove 98%, 92% and 99% of Congo red, Titan yellow and Eriochrome blue black R, respectively. Under the same conditions, the removal rate was 87%, 84% and 88% after 5 times adsorption cycle, respectively. Pseudo-first-order, pseudo-second-order kinetics, Elovich model and intraparticle diffusion model were studied, and the results show that the adsorption process conforms to pseudo-second-order kinetics model, and the diffusion rate is controlled by many steps. The results of isotherm model and thermodynamics show that the adsorption process is consistent with Langmuir model and is mainly a spontaneous chemical endothermic process of monolayer.
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26023. 题目: Photosensitized diastereoisomer-specific degradation of hexabromocyclododecane (HBCD) in the presence of humic acid in aquatic systems
文章编号: N19021605
期刊: Journal of Hazardous Materials
作者: Min-Hui Son, Jianyu Gong, Sunghee Seo, Hakwon Yoon, Yoon-Seok Chang
更新时间: 2019-02-16
摘要: Humic acids (HA) are the most important photosensitizers in the ocean and generate highly reactive oxygen species (ROS), known as photochemically produce reactive intermediates (PPRI), which degrade organic pollutants. Thus, to reveal the fate of organic pollutants in an aqueous environment, it is important to understand the natural photodegradation phenomenon caused by HA. Three ROS generated from HA, 1O2, O2-, and OH, were measured using different probe compounds and instrumental techniques. In this study, HBCD (hexabromocyclododecane), a newly listed one of persistent organic pollutants (POPs) under the Stockholm Convention, was studied to understand the phototransformation mechanism, which has not been sufficiently investigated in terms of its environmental fate and transport, despite the distinctive features of its diastereoisomers. The results showed that the diastereoisomer-specific distributions of α-, β-, and γ-HBCD were related to the acceleration and retardation of photodegradation in the presence of AHA (Aldrich Humic Acid) under simulated solar light, and only α-HBCD was rapidly photodegraded as the amount of AHA increased relative to the absence of AHA. This study provides the first characterization of the behavior of photosensitized HBCD degradation in aquatic systems.
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26024. 题目: Intense rainfalls trigger nitrite leaching in agricultural soils depleted in organic matter
文章编号: N19021604
期刊: Science of The Total Environment
作者: Micòl Mastrocicco, Nicolò Colombani, Elisa Soana, Fabio Vincenzi, Giuseppe Castaldelli
更新时间: 2019-02-16
摘要: Nitrate and ammonium are common inorganic contaminants of anthropogenic origin in many shallow aquifers around the world, while nitrite is less common, but it is most harmful than nitrate and ammonium due to its high reactivity. This paper presents evidence of nitrite accumulation after intense rainfalls in soil samples collected in an agricultural field characterized by organic matter chronic depletion. Moreover, an intact core from the same site was also collected to perform an unsaturated column experiment (60 cm long and 20 cm outer diameter) mimicking heavy rainfalls (230 mm in 2 days). Results from the field site showed nitrite accumulation (up to 0.45 mmol/kg) at 50–70 cm depth, just below the plough layer. The column experiment showed very high initial concentrations of nitrate and nitrite in the leachate and a progressive decrease of nitrate due to denitrification. The numerical flow model was calibrated versus the observed volumetric water contents and leachate flow rates. The numerical reactive transport model was calibrated versus the leachate concentrations of six dissolved species (ammonium, nitrate, nitrite, dissolved organic carbon, chloride and bromide). The optimized model resulted to be robustly calibrated providing insights on the kinetic rates driving the production, accumulation and leakage of nitrite, showing that incomplete denitrification is the source of nitrite. As far as the authors are aware, this is the first study reporting a clear link between high nitrite leaching rates and extreme rainfall events in lowland agricultural soils depleted in organic matter. The proposed methodology could be applied to quantify nitrite cycling processes in many other agricultural areas of the world affected by extreme rainfall events.
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26025. 题目: Strength assesment of al-humic and Al-Kaolin aggregates by intrusive and non-intrusive methods
文章编号: N19021603
期刊: Separation and Purification Technology
作者: Rodrigo B. Moruzzi, Pedro Grava da Silva, Soroosh Sharifi, Luiza C. Campos, John Gregory
更新时间: 2019-02-16
摘要: Resistance to breakage is a critical property of aggregates generated in water and wastewater treatment processes. After flocculation, aggregates should ideally keep their physical characteristics (i.e. size and morphology), to result in the best performance possible by individual separation processes. The integrity of aggregates after flocculation depends upon their capacity to resist shear forces while transported through canals, passages, apertures, orifices and other hydraulic units. In this study, the strength of Al-Humic and Al-Kaolin aggregates was investigated using two macroscopic measurement techniques, based on both intrusive and non-intrusive methods, using image analysis and light scattering based equipment. Each technique generates different information which was used for obtaining three floc strength indicators, namely, strength factor (SF), local stress from the hydrodynamic disturbance (σ) and the force coefficient (γ) for two different study waters. The results showed an increasing trend for the SF of both Al-Humic and Al-Kaolin aggregates, ranging from 29.7% to 78.6% and from 33.3% to 85.2%, respectively, in response to the increase of applied shear forces during flocculation (from 20 to 120 s-1). This indicates that aggregates formed at higher shear rates are more resistant to breakage than those formed at lower rates. In these conditions, σ values were observed to range from 0.07 to 0.44 N/m2 and from 0.08 to 0.47 N/m2 for Al-Humic and Al-Kaolin, respectively. Additionally, it was found that for all studied conditions, the resistance of aggregates to shear forces was nearly the same for Al-Humic and Al-Kaolin aggregates, formed from destabilized particles using sweep coagulation. These results suggest that aggregate strength may be mainly controlled by the coagulant, emphasizing the importance of the coagulant selection in water treatment. In addition, the use of both intrusive and non-intrusive techniques helped to confirm and expand previous experiments recently reported in literature.
26026. 题目: Molecular understanding of dissolved black carbon sorption in soil-water environment
文章编号: N19021602
期刊: Water Research
作者: Lei Luo, Zien Chen, Jitao Lv, Yuan Cheng, Tong Wu, Rixiang Huang
更新时间: 2019-02-16
摘要: Dissolved black carbon (DBC) involves in many biogeochemical processes in both terrestrial and aquatic environments. About 26.5 Tg of charcoal- or black carbon-derived DBC was released into aquatic environments annually, accounting to ∼10% of the global riverine flux of dissolved organic carbon (DOC). Yet the sorption behaviors of DBC and their effects on water quality in soil-water environment are poorly understood. Here we examined the molecular composition variations of DOC induced by the sorption of two biochar-derived DBCs (pyrolyzed at 300 oC and 500oC) on three contrasting soils. The DBCs were adsorbed mainly through competitive displacement of soil surface functional groups and co-sorption with soil indigenous DOC, which varied with soil properties and the aromaticity of the DBCs. Ultrahigh resolution mass spectrometry analysis indicated that compounds with rich oxygen content or unsaturated structures such as tannins and unsaturated aromatics from both DBC and soil DOC, were preferentially adsorbed on the soils in the presence of DBC. In contrast, compounds with high aromatic structures including condensed aromatics and lignins were concentrated in the aquatic phase. Molecular fractionation also occurred to the heteroatomic compounds during the sorption, and the heteroatomic dissolved organic sulphur in the DBCs was easier to be adsorbed relative to dissolved organic nitrogen. Our results suggest that DBC sorption in soil-water environment could have important implications for water quality by altering DOC molecular composition and decreasing DOC molecular diversity at the soil-water interface. This study provides essential information for understanding the behavior of DBC in the environments.
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26027. 题目: Modeling the fate of organic nitrogen during anaerobic digestion: development of a bioaccessibility based ADM1
文章编号: N19021601
期刊: Water Research
作者: Y. Bareha, R. Girault, S. Guezel, J. Chaker, A. Trémier
更新时间: 2019-02-16
摘要: Simulating the fate of nitrogen during anaerobic digestion is required to predict the characteristics of digestates and to improve their exploitation for agricultural uses. The aim of this study was to develop a modified ADM1 model that includes bioaccessibility-based fractionation to accurately simulate the fate of nitrogen during anaerobic digestion. To this end, two complementary approaches were used: (i) changes in the bioaccessibility of protein and non-protein compounds were assessed on eight substrates during anaerobic digestion in batch experiments using the “EPS” fractionation method; (ii) experimental results were used to develop a bio-kinetic model based on anaerobic digestion model n°1. This new model incorporates bioaccessibility-based fractionation in its input state variables. The model was successfully calibrated and model evaluation showed that predicted methane production, ammonium production and changes in protein and non-protein bioaccessibility during anaerobic digestion were accurate.
26028. 题目: Detection of Biochar Carbon by Fluorescence and Near-Infrared-Based Chemometrics
文章编号: N19021503
期刊: Aquatic Geochemistry
作者: Minori Uchimiya, Alan J. Franzluebbers, Zhongzhen Liu, Marshall C. Lamb, Ronald. B. Sorensen
更新时间: 2019-02-15
摘要: Large-scale biochar field trials have been conducted worldwide to test for “carbon negative strategy” in the event of carbon credit and if other subsidies become enacted in the future. Once amended to the soil, biochar engages in complex organo-mineral interactions, fragmentation, transport, and other aging mechanisms exhibiting interactions with treatments including the irrigation and fertilizer application. As a result, quantitative tracing of biochar carbon relying on the routinely measured soil parameters, e.g., total/particulate organic carbon, poses a significant analytical uncertainty. This study utilized two biochar field trial sites to calibrate for the biochar carbon structure and quantity based on the infrared- and fluorescence-based chemometrics: (1) slow pyrolysis biochar pellets on kaolinitic Greenville fine sandy loam in Georgia and (2) fast pyrolysis biochar powder on Crider silt loam in Kentucky. Partial least squares-based calibration was constructed to predict the amount of solvent (toluene/methanol)-extractable fluorescence fingerprint (290/350 nm excitation and emission peak) attributed to biochar based on the comparison with the authentic standard. Near-infrared-based detection was sensitive to the C–H and C–C bands, as a function of biochar loading and the particulate organic carbon content (< 53 μm) of the bulk soil. Developed chemometrics could be used to validate tarry carbon structures intrinsic to biochar additives, as the impact of biochar additives on soil chemical properties (pH, electric conductivity, and dissolved organic carbon) becomes attenuated over time.
26029. 题目: Mercury Sorption and Desorption on Organo-Mineral Particulates as a Source for Microbial Methylation
文章编号: N19021502
期刊: Environmental Science & Technology
作者: Lijie Zhang, Shan Wu, Linduo Zhao, Xia Lu, Eric M Pierce, Baohua Gu
更新时间: 2019-02-15
摘要: In natural freshwater and sediments, mercuric mercury (Hg(II)) is largely associated with particulate minerals and organics, but it remains unclear under what conditions particulates may become a sink or a source for Hg(II) and whether the particulate-bound Hg(II) is bioavailable for microbial uptake and methylation. In this study, we investigated Hg(II) sorption–desorption characteristics on three organo-coated hematite particulates and a Hg-contaminated natural sediment and evaluated the potential of particulate-bound Hg(II) for microbial methylation. Mercury rapidly sorbed onto particulates, especially the cysteine-coated hematite and sediment, with little desorption observed (0.1–4%). However, the presence of Hg-binding ligands, such as low-molecular-weight thiols and humic acids, resulted in up to 60% of Hg(II) desorption from the Hg-laden hematite particulates but <6% from the sediment. Importantly, the particulate-bound Hg(II) was bioavailable for uptake and methylation by a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under anaerobic incubations, and the methylation rate was 4–10 times higher than the desorption rate of Hg(II). These observations suggest direct contacts and interactions between bacterial cells and the particulate-bound Hg(II), resulting in rapid exchange or uptake of Hg(II) by the bacteria. The results highlight the importance of Hg(II) partitioning at particulate–water interfaces and the role of particulates as a significant source of Hg(II) for methylation in the environment.
26030. 题目: Transforming jhum to plantations: Effect on soil microbiological and biochemical properties in the foot hills of North Eastern Himalayas, India
文章编号: N19021501
期刊: CATENA
作者: Lungmuana, S.B. Singh, B.U. Choudhury, Vanthawmliana, Saurav Saha, Vanlalremruati Hnamte
更新时间: 2019-02-15
摘要: Slash and burn cultivation (jhum), a major form of traditional agriculture in the hills of north eastern Himalaya has now slowly shifted towards more stable forms of land use. This land use change in the region may have direct effect on soil quality which is an important concern for sustainable land use system. Our aim was to elucidate the impact of different land use from jhum cultivation on soil biological and biochemical properties. We have assessed the impact of such changes by comparing current jhum with replacement by plantations and forests for lengths of time varying from 15 to 30 years. The conversion to plantations (teak, arecanut and rubber) and secondary forests significantly increased the soil's water holding capacity (WHC) and soil organic carbon (SOC) contents. The SOC accumulation improved the moisture storage and increased soil microbiological processes such as microbial biomass C and N (MBC and MBN), percent of MBC to SOC, basal respiration and soil enzymes (acid and alkaline phosphatase, arylsulphatase, β–glucosidase, dehydrogenase and urease). The substrate use efficiency (metabolic quotient: qCO2) under jhum (J) was 21.5%, 25.8%, 27.8%, 39.9% higher than secondary forest (F), arecanut (A), rubber (R) and teak (T) respectively in the surface soil layer (0–15 cm) indicating microbial stress due to recent disturbances. The soil quality as defined by the geometric mean (G) over the soil depths followed the order F > R > A > T > J. Principal component analysis (PCA) was useful in discriminating the importance of soil microbiological and biochemical properties for land use change. In conclusion, land use change from jhum to forest and plantations (rubber and arecanut) conserved and improved soil quality.
26031. 题目: Impact of biochar-supported zerovalent iron nanocomposite on the anaerobic digestion of sewage sludge
文章编号: N19021419
期刊: Environmental Science and Pollution Research
作者: Min Zhang, Jianhua Li, Yuncai Wang
更新时间: 2019-02-14
摘要: Anaerobic digestion (AD) is an attractive technology for sludge treatment as it stabilizes sludge and produce renewable energy. However, problems such as low organic matter content and high heavy metals level are often encountered which severely limits the effectiveness of AD. In this study, the biochar-supported nanoscale zerovalent iron (nZVI-BC) was synthesized and used as additives during AD of sewage sludge to investigate the enhancement effects for methane production and its impacts on microbial structure at mesophilic temperature. nZVI-BC addition enhanced process stability by improving the generation and degradation of intermediate organic acids, but inhibitory effects were observed at high dosage. The methane content and cumulative methane yields were increased by 29.56% and 115.39%, respectively. Compared with AD without nZVI-BC, the application of nZVI-BC showed positive effect on improvement of metals (Cu, Cd, Ni, Cr, and Zn) stabilization in the digestate. Microbial community analysis illustrated that nZVI-BC addition could significantly increase the Shannon diversity index and Chao1 richness index of archaea, and meanwhile archaea were more diverse in nZVI-BC amended digesters than in control. It was notable that Methanosaeta dominated in all the digesters at genera level, while the relative abundance of hydrogenotrophic methanogens (Methanobacterium and methanospirillum) increased 35.39% in nZVI-BC amended digesters compared to the control, resulting in higher methane production. The results will guide development of microbial management methods to enhance the stability of AD process.
26032. 题目: Effect of earthworms and plants on the efficiency of vertical flow systems treating university wastewater
文章编号: N19021418
期刊: Environmental Science and Pollution Research
作者: Stevo Lavrnić, Sandra Cristino, Maribel Zapater-Pereyra, Jan Vymazal, Domenico Cupido, Giovanni Lucchese, Benedetta Mancini, Maurizio L. Mancini
更新时间: 2019-02-14
摘要: One of the possible ways to improve the operation efficiency of constructed wetlands and to prevent their clogging is the application of earthworms. They have already been successfully applied for vermicomposting and for sludge dewatering and treatment. A few studies have already examined the effect of earthworms on the treatment of wastewater by vertical flow constructed wetlands (VFCWs), but none of them have provided a yearlong research result from an open-air system or compared the effect that different seasons in a temperate climate area can have on these invertebrates. The goal of this research was to estimate the effect that earthworms and plants have on VFCW’s operation. Four mesocosms (a filter, a filter with earthworms, a VFCW and a VFCW with earthworms) were built and their influent and effluent water quality was monitored for a period of 1 year. They were fed with wastewater coming from a building of the University of Bologna (Italy). The results have shown that the presence of earthworms in this specific system did not reduce the organic matter content of the substrate, but it has positively influenced plants’ growth. However, since neither earthworms nor plants had a statistically significant effect on the effluent quality, it can be concluded that the integration of these invertebrates cannot improve wastewater treatment of vertical flow filters or constructed wetlands.
26033. 题目: Impact of zero-till residue management and crop diversification with legumes on soil aggregation and carbon sequestration
文章编号: N19021417
期刊: Soil and Tillage Research
作者: Narendra Kumar, Chaitanya Prasad Nath
更新时间: 2019-02-14
摘要: We evaluated the long-term impact of zero tillage (ZT) in post–rainy seasons (winter and summer) crop/s, crop residue management, and crop diversification on soil aggregation and carbon sequestration. The field experiment (started in 2009) was undertaken in split-plot design for seven consecutive years on a sandy loam soil of Kanpur, India. The experiment comprised of four tillage and crop residue management treatments: PTR – conventional tillage (CT) without crop residue (PTR–CT), PTR – ZT without crop residue (PTR–ZT–R), PTR – CT with crop residue incorporation (PTR–CT+R), and PTR – ZT with surface crop residue retention (PTR–ZT + R) in main plot, and three cropping systems: rice–wheat (RW), rice–chickpea (RC), and rice–chickpea–mungbean (RCMb) in subplot. Treatment PTR–ZT + R resulted in 13% (p < 0.05) higher water stable macroaggregate over the PTR–CT. Meantime, PTR–ZT+R increased carbon content in macro- aggregate (28%) and meso-aggregate (39%) over the PTR–CT, because of added carbon through the surface-laden crop residue. The tillage and crop residue management followed the sequence of PTR–ZT+R > PTR–ZT–R > PTR–CT+R > PTR–CT (p < 0.05) across the soil depths for active and passive carbon pools. After seven years, PTR–ZT+R enhanced soil microbial biomass carbon (SMBC) and particulate organic carbon (POC) by 70 and 56% over PTR–CT, respectively. The RCMb and RC rotations increased (p < 0.05) the macro– and meso– aggregates, and aggregate mean weight diameter compared to the RW rotation in both soil depths. Crop rotations had the following trend: RCMb > RC > RW (p < 0.05) for SMBC and POC. Notably, treatment PTR–ZT+R with RCMb or RC rotations largely increased the carbon management index compared to the PTR–CT and RW systems. The structural indices and soil carbon parameters were significantly correlated to the rice grain yield, except microaggregated carbon. Thus, crop diversification with grain legume/s, zero tillage in post rainy season crop/s, and crop residue retention provided not only higher soil aggregation but also increased carbon sequestration in Inceptisol of subtropical humid climate.
26034. 题目: Differential Incorporation of Bacteria, Organic Matter, and Inorganic Ions into Lake Ice during Ice Formation
文章编号: N19021416
期刊: Journal of Geophysical Research: Biogeosciences
作者: Pamela A. Santibáñez, Alexander B. Michaud, Trista J. Vick‐Majors, Juliana D’Andrilli, Amy Chiuchiolo, Kevin P. Hand, John C. Priscu
更新时间: 2019-02-14
摘要: The segregation of bacteria, inorganic solutes, and total organic carbon between liquid water and ice during winter ice formation on lakes can significantly influence the concentration and survival of microorganisms in icy systems, and their roles in biogeochemical processes. Our study quantifies the distributions of bacteria and solutes between liquid and solid water phases during progressive freezing. We simulated lake ice formation in mesocosm experiments using water from perennially (Antarctica) and seasonally (Alaska and Montana, USA) ice covered lakes. We then computed concentration factors and effective segregation coefficients, which are parameters describing the incorporation of bacteria and solutes into ice. Experimental results revealed that, contrary to major ions, bacteria were readily incorporated into ice and did not concentrate in the liquid phase. The organic matter incorporated into the ice was labile, amino acid‐like material, differing from the humic‐like compounds that remained in the liquid phase. Results from a control mesocosm experiment (dead bacterial cells) indicated that viability of bacterial cells did not influence the incorporation of free bacterial cells into ice, but did have a role in the formation and incorporation of bacterial aggregates. Together, these findings demonstrate that bacteria, unlike other solutes, were preferentially incorporated into lake‐ice during our freezing experiments, a process controlled mainly by the initial solute concentration of the liquid water source, regardless of cell viability.
26035. 题目: Different responses of dissolved black carbon and dissolved lignin to seasonal hydrological changes and an extreme rain event
文章编号: N19021415
期刊: Journal of Geophysical Research: Biogeosciences
作者: Hongyan Bao, Jutta Niggemann, Dekun Huang, Thorsten Dittmar, Shuh‐Ji Kao
更新时间: 2019-02-14
摘要: Hydrology, especially extreme hydrological events, has been recognized as an important driver of the land‐to‐ocean export of terrigenous dissolved organic matter (tDOM). Nevertheless, how various types of tDOM that differ in source and reactivity respond to changes in hydrology is not known. Seasonal and event exports of dissolved organic carbon (DOC), dissolved black carbon (DBC) and dissolved lignin were studied in a small subtropical river. We found that seasonal variations in DBC concentration were significantly related to hydrology, while DOC and dissolved lignin were not. In contrast, DOC, DBC and dissolved lignin changed similarly during an extreme rain event. The variation magnitudes of DOC, DBC and dissolved lignin concentrations were in the lower end compared to other rivers, which may be related to the limited coverage of wetlands and riparian vegetation and poor development of organic‐rich soil. Dilution effects were observed when the runoff exceeded 0.4 mm hr‐1, and the fluxes of both DBC and dissolved lignin decreased during the runoff peak, which was caused by surface flow and potentially by removal processes during peak discharge. Our results suggest that the influence of extreme rain events varies with tDOM source and reactivity and that high enough runoff (e.g., 0.7 mm hr‐1 in the Jiulong River) may not enhance the export rate of tDOM. However, our study was carried out in a small watershed with limited wetlands and riparian vegetation, and more studies are needed to verify whether this trend is consistent among global rivers.
26036. 题目: Field-aged biochar reduces the greenhouse gas balance in a degraded vegetable field treated by reductive soil disinfestation
文章编号: N19021414
期刊: Environmental Science and Pollution Research
作者: Bo Li, Jun Zhou, Ying Lu, Zhengqin Xiong
更新时间: 2019-02-14
摘要: Reductive soil disinfestation (RSD) is proposed as a pre-plant, non-chemical soil disinfestation technique to control several soilborne phytosanitary issues. However, limited information is available on the evaluation of greenhouse gas (GHG) balance and soil quality during the soil remediation process as affected by RSD method. A 44-day field experiment including four different treatments was conducted to investigate the effects of conventional RSD and field-aged biochar-amended RSD on GHG balance and soil quality in a degraded vegetable field. Results showed that the conventional RSD application can significantly decrease the soil nitrate (NO3−) concentrations and electrical conductivity (EC) and oxidation-reduction potential (Eh) by 51.4–67.3%, 5.3–23.6%, and 10.9–15.1%, respectively, while significantly increase soil pH and cation exchange capacity (CEC) by 0.37–0.42 units and 7.8–32.2%, respectively, in relation to the control (CK). Compared with the conventional RSD treatment, aged biochar-amended RSD significantly reduced soil NO3− concentrations, EC and Eh. No significant differences on CH4 emissions were observed among all the treatments during the experimental period. However, the conventional RSD application significantly increased the cumulative nitrous oxide (N2O) and carbon dioxide (CO2) emissions by 66.2–124.7% and 64.3–130.0%, respectively, and thus resulted in a significant GHG balance of 64.1–130.1% in relation to the CK. On the contrary, although resulted in more N2O emissions compared with the conventional RSD treatment, aged biochar-amended RSD significantly reduced the cumulative CO2 emissions and thus had an overall decrease in GHG balance by 20.7–28.7%. Therefore, aged biochar-amended RSD can simultaneously achieve lower GHG balance and better improvement of soil quality in degraded vegetable field, and thus can be utilized as an effective technology for soil remediation in intensive vegetable production.
26037. 题目: The effects of land abandonment and long‐term afforestation practices on the organic carbon stock and lignin content of Mediterranean humid mountain soils
文章编号: N19021413
期刊: European Journal of Soil Science
作者: J. Campo, R. J. Stijsiger, E. Nadal‐Romero, E. L. H. Cammeraat
更新时间: 2019-02-14
摘要: Afforestation is an important strategy that can decrease atmospheric carbon by sequestering carbon in biomass and soil. In Spain, an active afforestation programme was adopted in the 1950s when the soil was severely eroded after widespread abandonment of arable land. The Araguás catchment (Central Spanish Pyrenees) is a good example of this programme because it was afforested with both Pinus sylvestris L. (PS) and Pinus nigra J.F.Arnold (PN). The soil organic carbon (SOC) stock and lignin content (based on the vanillyl, syringyl and cinnamyl contents) of these afforested soils were examined, and compared to those of bare soil, secondary succession and meadow soils. Both the SOC stock and lignin content were used to evaluate the effects of land‐use changes on soil. Curie‐point pyrolysis with tetramethylammonium hydroxide was used to assess the lignin content. In the bare soil, there was none of the lignin compounds. The largest SOC stock and lignin content occurred under PN and secondary succession sites. A decreasing trend for the lignin content, related to the limited organic matter input and the longer degradation period, was observed at deeper horizons in all soils except meadows. These meadow soils also showed increased SOC stocks in deeper horizons. Land abandonment reduced the SOC stock although no significant differences were observed in the organic carbon incorporation assessed through lignin content (and if this was so it was restricted to the top centimetre or so). According to the results, PN was the best afforestation practice for increasing SOC stock and lignin content in soil. Pinus sylvestris afforestation was less successful than secondary succession, at increasing SOC sequestration and lignin content.
26038. 题目: Bacterial community enhances flocculation efficiency of Ettlia sp. by altering extracellular polymeric substances profile
文章编号: N19021412
期刊: Bioresource Technology
作者: Chau Hai Thai Vu, Seong-Jun Chun, Seong-Hyun Seo, Yingshun Cui, Chi-Yong Ahn, Hee-Mock Oh
更新时间: 2019-02-14
摘要: This study examined the effects of a bacterial community and extracellular polymeric substances (EPS) on Ettlia sp. flocculation. The growth rate, flocculation efficiency (FE), bacterial community, and EPS profile of axenic and xenic Ettlia cultures were monitored during 46 days of cultivation. For the xenic culture, with a great abundance of growth-promoting and flocculation-inducing bacteria, the biomass density was 18.75% higher and its FE reached 100% in the mid-stationary phase. Moreover, microscopic observation and a quantitative analysis of the EPS revealed the exclusive presence of long filamentous EPS and more compact structure in the xenic Ettlia culture, possibly explaining its better FE. Notwithstanding, for the axenic culture, despite a lower biomass density and reduced abundance of EPS, its FE reached 92.54% in the mid-stationary phase. Thus, the role of the bacterial community was found to be supportive rather than vital for the high settleability of the self-flocculating Ettlia microalgal culture.
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26039. 题目: Afforestation of loess soils: Old and new organic carbon in aggregates and density fractions
文章编号: N19021411
期刊: CATENA
作者: Rui Jiang, Anna Gunina, Dong Qu, Yakov Kuzyakov, Yajun Yu, Ryusuke Hatano, Kwame A. Frimpong, Ming Li
更新时间: 2019-02-14
摘要: Afforestation is an important strategy to increase soil organic carbon (SOC) stocks and stabilize soils against degradation and erosion. While the area under afforestation has increased globally during the last 20 years, the dynamics of SOC accumulation due to afforestation are still poorly known, as it cannot be directly compared to that in cropland. The goals of this study were: i) to investigate the dynamics of SOC accumulation after afforestation on the Loess Plateau; ii) to determine SOC contents and distribution in density fractions and aggregates most strongly affected by afforestation; and iii) to analyze the relationships between old and new SOC in relation with afforestation periods. A chronosequence of forest plots aged 1, 5, 12 (with Chinese pine, Pinus tabulaeformis Carr.) and 30 years (with white poplar, Populus alba L.) were selected within the large scale “Grain for Green” project. A maize field nearby was chosen as a control, which represents the land use prior to afforestation. At each location, soils were sampled at depths of 0–10 and 10–30 cm, respectively and aggregates were fractionated into <250, 250–2000 and > 2000 μm sizes, which were subsequently separated into light (ρ < 1.85 g cm−3) and heavy (ρ > 1.85 g cm−3) density fractions. SOC content was generally higher in afforested soils than in cropland and increased with stand age. The mean SOC accumulation rate was 0.11 g C kg−1 year−1 for the 0–10 cm layer of the 30-year-old forests, whereas the maximum rate was found for 5-year-old forest at 0.24 g C kg−1 year−1. For each period of afforestation, the maximum SOC content was recorded in the macroaggregates. The C turnover of the light fraction (calculated based on δ13C of SOC) peaked in the large macroaggregates and ranged from 21 to 23 years). Whereas SOC turnover in the heavy fraction, peaked in the microaggregates at a relatively longer period of 46 to 70 years. We conclude that the initial SOC accumulation under afforestation occurs mainly in the macroaggregates, with a faster turnover compared with microaggregates. During the first 30 years of afforestation, the SOC accumulation and stabilization is ongoing mainly in the upper 10 cm, while the C sequestration in 10 to 30 cm depth needs much longer time.
26040. 题目: Biochar-mediated sequestration of Pb and Cd leads to enhanced productivity in Mentha arvensis
文章编号: N19021410
期刊: Ecotoxicology and Environmental Safety
作者: Nidhi Nigam, Puja Khare, Vineet Yadav, Disha Mishra, Shilpi Jain, Tanmoy Karak, Saumik Panja, S. Tandon
更新时间: 2019-02-14
摘要: Immobilization of cadmium (Cd) and lead (Pb) along with the alleviation of their phytotoxicity in Mentha arvensis by biochar was examined in this investigation. A greenhouse experiment was executed to evaluate the effect of biochar (BC) amended Cd and Pb spiked soil on their immobilization and uptake, plant growth, photosynthetic attributes (total chlorophyll, photosynthetic rate, transpiration rate, and stomatal activity) and oxidative enzymes (guaiacol peroxidase: POD; catalase: CAT and superoxide dismutase: SOD). In the present study, the photosynthetic attributes showed that BC significantly improved the total chlorophyll, photosynthetic, transpiration rates, and stomatal activity in the plants. The incorporation of BC in soil increase the Pb and Cd tolerance in M. arvensis vis-à-vis improved the biomass yield and nutrient intake. In addition, biochar has also reduced the POD, CAT, and SOD in the plant as well as improved the soil pH and enzymatic activities. Overall, BC immobilized the Cd and Pb in soil by providing the binding site to the metals and reduced the phytotoxicity in M. arvensis. However, large-scale field trials of BC are required for safe cultivation of M. arvensis which is known for its phytopharmaceuticals importance.
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