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23601. 题目: Nano-biochar reduced soil erosion and nitrate loss in sloping fields on the Loess Plateau of China
文章编号: N19120406
期刊: CATENA
作者: Xiaopeng Chen, Beibei Zhou, Quanjiu Wang, Wanghai Tao, Henry Lin
更新时间: 2019-12-04
摘要: The effects of biochar on soil erosion and nutrient loss on the Chinese Loess Plateau have been well reported, but the huge required application rate of biochar limits the biochar use. The specific nano-treatment can improve the distribution and properties of biochar (e.g., increase the specific surface area). To investigate the migration processes of runoff, sediment and nutrients on the nano-biochar (NB) applied sloping land during rainfall events, different mass content of NB (0.0%, 0.1%, 0.5%, 0.7%, and 1.0%) were used on the three types of vegetation covered sloping land (bare, caragana, and maize). The effects of NB and vegetation on runoff volume, sediment yield, and nitrate loss were studied under simulated rainfall in the northeastern region of the Loess Plateau. The main results were as follows: the application of NB effectively reduced runoff (39.7–74.4%), sediment yield (8.9–41.8%), and nitrate loss (13.6–59.8%) in all treatments. Losses of nitrate in runoff and sediment were negatively correlated with increased content of NB (when NB application rate was 1.0%, the maximum nitrate loss in runoff and sediment were 27.43 and 6.25 mg, respectively). The equivalent model of convection was more suitable for analyzing the nutrient transfer process with the application of NB. The effective mixing depth decreased with NB content and could be well described by a power function. NB might promote the nitrate migrate to deep soil and reduce nitrate loss in runoff and sediment. With NB application, the peak value of nitrate distribution in the profile moved downward, and the maximum value was obtained at 10–15 cm. Moreover, the most effective NB content for reducing nitrate loss were 1.0%. Comparing with bare and maize, caragana had the most significant effect on reducing runoff, sediment and nutrient loss. In addition, Synergistic effect of NB and caragana showed the great potential on soil and water loss control. The findings in this study provide an efficient and economic method for controlling soil erosion and nutrient loss on the Chinese Loess Plateau.

23602. 题目: Soil conservation in an abandoned agricultural rain-fed land through inoculation of cyanobacteria
文章编号: N19120405
期刊: CATENA
作者: Hossein Kheirfam, Seyed Hamidreza Sadeghi, Behrouz Zarei Darki
更新时间: 2019-12-04
摘要: Newly abandoned rain-fed lands, due to soil quality decline, are the main sources for soil erosion in semi-dry lands agricultural hill-slopes. However, adopting compatible environmentally friend measures have not been adequately implemented. Following various resultful laboratory studies, in this paper, we assessed the effect of field inoculation of cyanobacteria in an abandoned rain-fed land on controlling the natural rainfall-induced soil loss and improving the biological soil crust (BSC) quality mixture of two cyanobacteria (viz. Nostoc sp. and Oscilatoria sp.). The cyanobacteria were inoculated on 22.1 m × 1.83 m-sized plots located on the study hill-slope. The experiment was carried out for a rainfall period of 6 months under natural conditions. Measurements of 7 erosive rainfalls showed a considerable soil loss (i.e., 0.88 ± 0.10 to 9.79 ± 1.60 g m⁻²) from the un-inoculated plots (control), while cyanobacteria decreased the soil loss by 36 to 57% in comparison with those recorded for the control. Soil losses in the inoculated plots were 2.39 ± 0.24, 4.8 ± 0.58, 3.32 ± 0.33, 1.49 ± 0.12, 0.87 ± 0.12, 0.52 ± 0.05, and 0.56 ± 0.08 g m⁻², from the first to last rainstorms, respectively. Our results, therefore, showed a poor linear relationship between soil loss (from both treatments) and rainfall properties. Cyanobacteria also improved organic carbon and nitrogen contents as two important BSC quality indicators to the tunes of 32 and 56%, respectively, in comparison to the control, during the study period. In winter, when environmental conditions were inappropriate for growing vegetation, the effect of cyanobacteria on soil loss reduction was found to be more tangible in comparison with spring. On the whole, our field soil inoculation under uncontrolled conditions, as pioneering research, facilitated to promising results for large-scale use of cyanobacteria to rapidly restore abandoned rain-fed lands.
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23603. 题目: A cascading influence of calcium carbonate on the biogeochemistry and pedogenic trajectories of subalpine soils, Switzerland
文章编号: N19120404
期刊: Geoderma
作者: Mike C. Rowley, Stephanie Grand, Thierry Adatte, Eric P. Verrecchia
更新时间: 2019-12-04
摘要: Soil research in temperate to cool and humid regions has typically focused on acidic soils; there has been relatively little investigation of the effects of calcium carbonate (CaCO₃) on unamended soil properties or function in these environments. The object of this study was to characterise the effects of small amounts of CaCO₃ on pedogenic trajectories and soil biogeochemistry in a humid subalpine valley of Switzerland. To isolate the influence of CaCO₃, six profiles were selected that had developed under almost identical conditions for soil formation, i.e. climate, topography, vegetation structure, time since deglaciation, silicate mineralogy and texture. The main difference between the profiles was that three contained a small quantity of CaCO₃ (<6.2%; thereafter, ‘CaCO₃-bearing’) while the remaining three contained no detectable CaCO₃ (thereafter, ‘CaCO₃-free’). The presence of CaCO₃ was associated with cascading changes in soil biogeochemistry. These changes included higher pH, an order of magnitude higher extractable Ca and twice as much soil organic carbon (SOC). CaCO₃-bearing profiles also displayed a higher proportion of poorly crystalline Fe forms. The higher pH at the CaCO₃-bearing site was attributable to the weak buffering provided by CaCO₃ dissolution, which in turn maintained the relatively higher extractable Ca. Exchangeable Ca (Ca_Exch) and other reactive Ca forms could help stabilise SOC, contributing to its accumulation through processes such as flocculation and subsequent occlusion within aggregates and/or sorption to mineral surfaces. The increased SOC, Ca_Exch and pH at the CaCO₃-bearing site could in turn be inhibiting the crystallisation of disordered Fe forms, but further research is required to confirm this effect and isolate the exact mechanisms. Overall, this study shows that the presence of small amounts of CaCO₃ in humid environments has a far-reaching influence on soil biogeochemistry and further supports the idea that indicators of Ca prevalence have the potential to improve regional SOC estimates.
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23604. 题目: Biochar phosphorus fertilizer effects on soil phosphorus availability
文章编号: N19120403
期刊: Chemosphere
作者: Haixiao Li, Yuxin Li, Yan Xu, Xueqiang Lu
更新时间: 2019-12-04
摘要: Biochar is a potential material for making slow-releasing phosphorus (P) fertilizers for the sake of increasing soil P use efficiency and mitigating P losses. However, the long-term effects of P-laden biochars on soil P availability remains unconcerned. In this study, a laboratory-scale 70-days soil incubation experiment was conducted to study the effects of original and P-laden biochars on soil P availability and fractions. Two original biochars were derived from maize stalks by pyrolyzing at 350 °C and 600 °C. P was laden on those biochars by immersing biochars in saturated KH₂PO₄ solution for 24 h. Eight treatments were set for the incubation experiment, which were soil, soil + triple-superphosphate (TSP), soil + 350 °C biochar, soil + 600 °C biochar, soil + TSP + 350 °C biochar, soil + TSP + 600 °C biochar, soil + 350 °C P-laden biochar, and soil + 600 °C P-laden biochar. Results showed that original biochars could decrease soil available P through P adsorption. And there were no significant differences of soil P fractions under the treatments of mineral P fertilizer and P-laden biochars. Whereas, compared to mineral P fertilizer, P-laden biochars, especially 600 °C P-laden biochar, could maintain soil available P in a significantly higher level across the incubation. It was mainly because of the slow-releasing pattern of P laden on biochar and a more homogeneous soil P source distribution under P-laden biochar treatments. These results indicated that P-laden biochar could work as P fertilizer to improve soil P use efficiency.

23605. 题目: Degradation behaviors of Isopropylphenazone and Aminopyrine and their genetic toxicity variations during UV/chloramine treatment
文章编号: N19120402
期刊: Water Research
作者: Bingqi Jiang, Yajun Tian, Zichen Zhang, Ze Yin, Li Feng, Yongze Liu, Liqiu Zhang
更新时间: 2019-12-04
摘要: Combination of ultraviolet and chloramine (i.e., UV/chloramine) treatment has been attracting increasingly attention in recent years due to its high efficiency in removing trace organic contaminants. This study investigated the degradation behaviors of two pyrazolone pharmaceuticals (i.e., Isopropyl phenazone (PRP) and Aminopyrine (AMP)) and their genetic toxicity variations during UV/chloramine treatment. The results showed that chloramine could hardly degrade PRP and AMP, while UV/chloramine greatly increased the observed first-order rate constant (k_obs) of PRP and AMP degradation. The quenching and probe experiments illustrated that the reactive chlorine species (RCS) contributed dominantly to PRP removal, and hydroxyl radical (HO^•) was the major contributor to the degradation of AMP, while the reactive amine radicals (RNS) could hardly degrade them. The overall degradation rates of PRP and AMP decreased as pH increased from 6.5 to 10. The k_obs of PRP and AMP increased along with NH₂Cl dosage increasing and reached a plateau at higher concentrations (0.2–0.5 mM). The present background carbonate (HCO₃⁻, 1–10 mM), chloride (Cl⁻, 1–10 mM) and natural organic matter (NOM, 5-10 mg-C L⁻¹) exhibited inhibition impacts on PRP and AMP degradation. In addition, the intermediates/products of PRP and AMP were identified and their general degradation pathways were proposed to be hydroxylation, deacetylation, and dephenylization. Specifically, Cl-substitution was inferred during PRP degradation, while demethylation in tertiary amine group was only observed in AMP degradation. These mechanisms including the main reactive sites of PRP and AMP were further confirmed by the frontier orbitals calculation. Moreover, the results of the genetic toxicity according to the micronucleus test of Viciafaba root tip indicated that UV/chloramine treatment could partially reduce the genetic toxicity of PRP and AMP.
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23606. 题目: Application of an enrichment culture of the marine anammox bacterium “Ca. Scalindua sp. AMX11” for nitrogen removal under moderate salinity and in the presence of organic carbon
文章编号: N19120401
期刊: Water Research
作者: Muhammad Ali, Dario Rangel Shaw, Pascal E. Saikaly
更新时间: 2019-12-04
摘要: Seawater can be directly used for toilet flushing in coastal areas to reduce our dependence on desalination and freshwater resources. The presence of high-salt content in the generated wastewater from seawater toilet flushing could limit the performance of conventional biological nitrogen removal processes. Anaerobic ammonium oxidation (anammox) process is regarded as one of the most energy-efficient process for nitrogen removal from N-rich waste streams. In this study, we demonstrated the application of a novel marine anammox bacterium (Candidatus Scalindua sp. AMX11) in a membrane bioreactor (MBR) to treat moderate-saline (∼1.2% salinity) and N-rich organic (2 mM acetate) solution, prepared using real seawater. The MBR showed stable performance with nitrogen removal rate of 0.3 kg–N m⁻³ d⁻¹ at >90% N-removal efficiency. Furthermore, results of ¹⁵N stable isotope experiments revealed that anammox bacteria was mainly responsible for respiratory ammonification through NO₃⁻ reduction to NH₄⁺ via NO₂⁻, and the by-products of respiratory ammonification were used as substrates by anammox bacteria. The dominant role of anammox bacteria in nitrogen removal under saline and organic conditions was further confirmed by genome-centric combined metagenomics and meta-transcriptomic approach. Taken together, these results highlight the potential application of marine anammox bacteria for treating saline wastewater generated from seawater toilet flushing practices.
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23607. 题目: Great Oxidation and Lomagundi events linked by deep cycling and enhanced degassing of carbon
文章编号: N19120305
期刊: Nature Geoscience
作者: James Eguchi, Johnny Seales, Rajdeep Dasgupta
更新时间: 2019-12-03
摘要: For approximately the first 2 billion years of the Earth's history, atmospheric oxygen levels were extremely low. It was not until at least half a billion years after the evolution of oxygenic photosynthesis, perhaps as early as 3 billion years ago, that oxygen rose to appreciable levels during the Great Oxidation Event. Shortly after, marine carbonates underwent a large positive spike in carbon isotope ratios known as the Lomagundi event. The mechanisms responsible for the Great Oxidation and Lomagundi events remain debated. Using a carbon–oxygen box model that tracks the Earth's surface and interior carbon fluxes and reservoirs, while also tracking carbon isotopes and atmospheric oxygen levels, we demonstrate that about 2.5 billion years ago a tectonic transition that resulted in increased volcanic CO2 emissions could have led to increased deposition of both carbonates and organic carbon (organic C) via enhanced weathering and nutrient delivery to oceans. Increased burial of carbonates and organic C would have allowed the accumulation of atmospheric oxygen while also increasing the delivery of carbon to subduction zones. Coupled with preferential release of carbonates at arc volcanoes and deep recycling of organic C to ocean island volcanoes, we find that such a tectonic transition can simultaneously explain the Great Oxidation and Lomagundi events without any change in the fraction of carbon buried as organic C relative to carbonate, which is often invoked to explain carbon isotope excursions.

23608. 题目: Semi-volatile components of PM2.5 in an urban environment: Volatility profiles and associated oxidative potential
文章编号: N19120304
期刊: Atmospheric Environment
作者: Milad Pirhadi, Amirhosein Mousavi, Sina Taghvaee, Martin M. Shafer, Constantinos Sioutas
更新时间: 2019-12-03
摘要: The volatility profiles of PM2.5 semi-volatile compounds and relationships to the oxidative potential of urban airborne particles were investigated in central Los Angeles, CA. Ambient and thermodenuded fine (PM2.5) particles were collected during both warm and cold seasons by employing the Versatile Aerosol Concentration Enrichment System (VACES) combined with a thermodenuder. When operated at 50 °C and 100 °C, the VACES/thermodenuder system removed about 50% and 75% of the PM2.5 vol concentration, respectively. Most of the quantified PM2.5 semi-volatile species including organic carbon (OC), water soluble organic carbon (WSOC), polycyclic aromatic hydrocarbons (PAHs), organic acids, n-alkanes, and levoglucosan, as well as inorganic ions (i.e., nitrate, sulfate, and ammonium) exhibited concentration losses in the ranges of 40–66% and 67–92%, respectively, as the thermodenuder temperature increased to 50 °C and 100 °C. Species in the PM2.5 such as elemental carbon (EC) and inorganic elements (including trace metals) were minimally impacted by the heating process – thus can be considered refractory. On average, nearly half of the PM2.5 oxidative potential (as measured by the dichlorodihydrofluorescein (DCFH) alveolar macrophage in vitro assay) was associated with the semi-volatile species removed by heating the aerosols to only 50 °C, highlighting the importance of this quite volatile compartment to the ambient PM2.5 toxicity. The fraction of PM2.5 oxidative potential lost upon heating the aerosols to 100 °C further increased to around 75–85%. Furthermore, we document statistically significant correlations between the PM2.5 oxidative potential and different semi-volatile organic compounds originating from primary and secondary sources, including OC (Rwarm, and Rcold) (0.86, and 0.74), WSOC (0.60, and 0.98), PAHs (0.88, and 0.76), organic acids (0.76, and 0.88), and n-alkanes (0.67, and 0.83) in warm and cold seasons, respectively, while a strong correlation between oxidative potential and levoglucosan, a tracer of biomass burning, was observed only during the cold season (Rcold = 0.81).

23609. 题目: Dissolved Organic Matter and Associated Trace Metal Dynamics from River to Lake, Under Ice-Covered and Ice-Free Conditions
文章编号: N19120303
期刊: Environmental Science & Technology
作者: Isabelle A. M. Worms, Hannah E. Chmiel, Jacqueline Traber, Natacha Tofield-Pasche, Vera I. Slaveykova
更新时间: 2019-12-03
摘要: The present study investigates the changes in dissolved organic matter (DOM) composition and its influences on trace metal dispersion from the Shuya River (SR) in the Petrozavodsk Bay of Lake Onega during ice-covered and ice-free periods. Humic substances (HS) found in the SR dominated the composition of DOM through the river-bay-lake continuum in both periods. When the bay was ice-covered, both the aromaticity and the size of HS varied in the water column according to a horizontal stratification and decreased in the bay, while under ice-free conditions, they decreased along the river-lake gradient, suggesting in both cases a decrease in the proportion of HS with high aromatic character. These findings were associated with an overall decrease in the proportion of HS components that have the highest molecular masses. The quantification of metal bound to HS revealed that these characteristics were associated with a decrease in the binding capacity of the HS for Fe and Al but not Cu while dispersing in the bay to the lake. Pb was found to bind on HS, but its behavior in the bay could not be related to the HS dispersion nor to the changes in HS properties.

23610. 题目: Influence of agro-industrial wastes on the sorption, desorption, and distribution of copper in soils polluted by mine tailings
文章编号: N19120302
期刊: Journal of Soils and Sediments
作者: Jorge Mendoza, Tatiana Garrido, Davor Cotoras, Francisco Arriagada
更新时间: 2019-12-03
摘要: Purpose: The objective of this work was to modify minimally two agro-industrial wastes, to evaluate their effectiveness for the retention of copper in soils contaminated by mining tailings, as well as to evaluate the changes in the chemical forms of the metal in the soil and thus also evaluate the attenuation of copper desorption in a short period after a mine tailing spill on the soil. Materials and methods: The solid wastes of olive mill and grape stalks of the wine-making process were modified minimally, through washing processes and partial alkalization, to obtain substrates with greater capacity for copper sorption. Two agricultural soils near a tailing impoundment were studied: a sandy loam soil with pH close to neutral and high total and available copper content and a clay soil with low copper content, slightly acid pH, and high clay content. Both soils were treated with mine tailings from the same site to simulate an involuntary spill of mining waste. The contaminated soils were treated with the organic amendments to study the sorption, desorption, and distribution of Cu in a period of 30 days. Results and discussion: The application of simple procedures such as alkalinization or washing of the agro-industrial wastes improved the Cu sorption capacity and facilitated the application of these materials to the soil. The application of mine tailings to the soils decreased the Cu sorption and the affinity of the substrate for the metal. This adverse effect was ameliorated by the incorporation of minimally treated olive mill wastes and grape stalks, increasing the sorption by a range of 15 to 75% compared to untreated soils. In substrates with sandy loam soil, both amendments decrease the soluble fraction of Cu, an effect that was not observed in clay soil. In parallel, both amendments increased the fraction of metal bound to the oxidizable fraction, an effect that was greater for grape stalks. Conclusions: The organic amendments used in this study were effective to reduce the initial contamination by copper after a spill of mine tailing wastes containing this metal. In this sense, both amendments applied to sandy loam soil increased the organic matter content and the Cu sorption capacity, effects that are maintained for at least 30 days. In clay soil, these effects were observed only for grape stalks, probably due to its greater metal sorbent capacity compared to the olive oil waste.

23611. 题目: Converting waste lignin into nano-biochar as a renewable substitute of carbon black for reinforcing styrene-butadiene rubber
文章编号: N19120301
期刊: Waste Management
作者: Can Jiang, Jinyu Bo, Xiefei Xiao, Shumin Zhang, Zuhao Wang, Guoping Yan, Yanguang Wu, Chingping Wong, Hui He
更新时间: 2019-12-03
摘要: Industrial waste lignin was commonly burnt or discharged into river in the past. However, in this study, lignin has been converted into high value-added nano-biochar as a renewable reinforcing filler of styrene-butadiene rubber (SBR) by a simple high-temperature carbonization treatment. Herein, the physicochemical change in lignin before and after carbonization was investigated. It was found that lignin-derived biochar (LB) consisted of vesicle-like primary nanoparticles which were closely packed to form “high-structure” irregular fragments with a high specific surface area (83.41 m²/g). When incorporating LB into SBR, the tensile properties of LB/SBR composites were significantly improved. At the filler loading of 40 phr, the tensile strength and elongation at break of the rubber composite were improved up to 7.1-folds and 2.4-folds of pristine SBR, respectively. Compared to commercial carbon black (CB) N330, the LB showed a similar reinforcing effect on SBR. However, the analysis on the morphology, stress-strain behavior and dynamic mechanical behavior suggested distinct reinforcing mechanisms for LB- and CB-filled rubber composites, due to the difference in the surface properties and structural characteristic of fillers. This work showed the application potential of LB as a renewable substitute of CB in rubber industry and brought environmental and economic benefits for the disposal of lignin.
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23612. 题目: Soil carbon and nitrogen pools, their depth distribution and stocks following plantation establishment in south east Queensland, Australia
文章编号: N19120202
期刊: Forest Ecology and Management
作者: J. Bernhard Wehr, Tom Lewis, Ram C. Dalal, Neal W. Menzies, Luke Verstraten, Scott Swift, Philippa Bryant, Neil Tindale, Tim E. Smith
更新时间: 2019-12-02
摘要: Changes in land use affect the soil organic carbon (SOC) stocks and pools. This is currently of great interest as soils are a major pool of carbon in the biosphere and can sequester atmospheric carbon. This study investigated the effect of pasture conversions into reforestation or cropping land on SOC, humic organic C (HOC), particulate organic C (POC) and resistant organic C (ROC) stocks, and soil nitrogen, to 0.5 m depth using mid infrared spectroscopy and combustion analyses. The ten study sites in south east Queensland, Australia were cleared of native vegetation to pasture decades earlier and were more recently (6–19 years ago) converted to either forest plantations (eucalypts) or cropping land. The SOC was significantly affected by land use and site location. Conversion of pasture to forest plantation had no significant effect on SOC compared to pasture up to 19 years since reforestation, but SOC increased slightly with plantation age at a rate of 3.03 t ha⁻¹ per year. Conversion of pasture to cropping land significantly decreased SOC. The stocks of SOC ranged from 47.0 to 107.6 t ha⁻¹. The HOC pool contributed the most towards the total SOC, and ranged from 17.7 to 67.8 t ha⁻¹ across all sites. The POC pool ranged from 2.1 to 17.8 t ha⁻¹ and the ROC pool varied between 5.3 and 22.3 t ha⁻¹. The total SOC stock determined by MIR was closely related to SOC determined by dry combustion analysis. Soil N was significantly affected by land use and location, but trends were not consistent. On pasture sites, total N was higher likely due to fertiliser applications and total N ranged between 3.7 and 15.0 t ha⁻¹ across sites. In summary, conversion of pasture to forest plantation had no significant effect on SOC stocks and different soil carbon pools over 19 years in the subtropical climate of south east Queensland.

23613. 题目: Long-term effectiveness of sustainable land management practices to control runoff, soil erosion, and nutrient loss and the role of rainfall intensity in Mediterranean rainfed agroecosystems
文章编号: N19120201
期刊: CATENA
作者: M. Martínez-Mena, E. Carrillo-López, C. Boix-Fayos, M. Almagro, N. García Franco, E. Díaz-Pereira, I. Montoya, J. de Vente
更新时间: 2019-12-02
摘要: Mediterranean environments are especially susceptible to soil erosion and to inappropriate soil management, leading to accelerated soil loss. Sustainable Land Management (SLM) practices (such as reduced tillage, no-tillage, cover crops, etc.,) have the potential to reduce soil, organic carbon (OC), and nutrient losses by erosion. However, the effectivity of these practices is site-dependent and varies under different rainfall conditions. The objective of this paper was to evaluate the effects of SLM practices – in two rainfed systems (a wheat field and an almond orchard) representative of a large area of the driest Mediterranean regions - on runoff, soil erosion, particle size distribution, and OC and nutrient (N and P) contents in sediments. The influence of the rainfall characteristics on the effectiveness of the SLM practices was also evaluated. The SLM implemented were: reduced tillage (RT) in the wheat field and almond orchard and reduced tillage combined with green manure (RTG) in the almond orchard; these were compared to conventional tillage, the usual practice in the area. Open erosion plots were set up to monitor the effects of SLM on soil carbon and nutrients and on soil erosion after each rainfall event over six years (2010–2016). The results show that the SLM practices evaluated resulted in increased organic carbon (OC) and nutrients (N and P) contents in the soil, and reduced runoff, erosion, and mobilization of organic carbon and nutrients in sediments. Reductions in runoff of 30% and 65% and decreases in erosion of 65 and 85% were found in the wheat field and almond orchards, respectively. In addition, the total OC, N, and P losses in the wheat field were reduced by 56%, 45%, and 64%, respectively, while in the almond field the OC, N, and P losses were reduced by 90% under RT and by 85% under RTG.The beneficial effect of the SLM practices on soil erosion was observed within 18 months of their implementation and continued throughout the six years of the study. Furthermore, the effectiveness of tillage reduction with respect to erosion control and carbon and nutrients mobilization was highest during the most intense rainfall events, which are responsible for the highest erosion rates in Mediterranean areas. Our results support the key role of SLM practices under semiarid conditions as useful tools for climate change mitigation and adaptation, given the expected increase in high-intensity rainfall events in semiarid areas.

23614. 题目: Immobilizing Microcystis aeruginosa and powdered activated carbon for the anaerobic digestate effluent treatment
文章编号: N19120104
期刊: Chemosphere
作者: Weijia Gong, Yuhui Fan, Binghan Xie, Xiaobin Tang, Tiecheng Guo, Lina Luo, Heng Liang
更新时间: 2019-12-01
摘要: The environment pollution caused by livestock anaerobic digestate effluent (ADE) is becoming increasingly severe recently. In this study, immobilized technology, embedding Microcystis aeruginosa (MA) and powdered activated carbon (PAC) with sodium alginate (SA), was employed to investigate the removal performance of nitrogen (N), phosphorus (P) and dissolved organic matter (DOM) in the treatment of ADE solution. Initially, orthogonal experiment was carried out to achieve the optimal conditions of the beads fabrication with the concentration of imbedding agents (PAC-SA) of 5% (w/w) and the ratio of microalgae and imbedding agents was 1:1 (v/v). The results indicated that the total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) can be efficiently removed under the optimal operation conditions, with average removals of 91.88 ± 2.91% in TN, 98.24 ± 0.12 in TP and 78.31 ± 1.57% in TOC, respectively. Moreover, the fluorescence excitation-mission matrix (EEM) results illustrated that IMA-PAC beads joined system can efficiently diminish the concentrations of protein-like compounds and humic substances. Therefore, the organic contaminants and nutrients (i.e. N and P) can be efficiently removed in IMA-PAC beads joined system, which would contribute to developing new strategies for the treatment of ADE solution and nutrient recycle.

23615. 题目: Changes in soil labile and recalcitrant carbon pools after land-use change in a semi-arid agro-pastoral ecotone in Central Asia
文章编号: N19120103
期刊: Ecological Indicators
作者: Xiang Liu, Ditao Chen, Tao Yang, Farong Huang, Shuai Fu, Lanhai Li
更新时间: 2019-12-01
摘要: Soil organic matter is a heterogeneous and complex entity that consists of a diverse range of compounds. However, the responses of soil organic carbon (SOC) fractions with different biochemical stabilities to land-use change are inadequately addressed. In this study, soil samples (0–60 cm) were collected with a 10 cm interval from grassland (GS), cropland (CS), woodland (WS), and orchard (OS) using paired-site approach in a typical semi-arid agro-pastoral ecotone in the Ili River Valley, Central Asia, to: (1) clarify the vertical changes in soil labile (LPI and LPII) and recalcitrant C pools (RP) after GS conversion to CS and CS conversion to WS and OS; and to (2) evaluate the impact of land-use change on SOC stability. The results indicated that LPI stocks in topsoil (0–30 cm) and subsoil (30–60 cm) showed opposite responses to land-use change. In contrast, LPII and RP stocks in both soil layers significantly decreased after conversion of GS to CS, and significantly increased after CS afforestation. These results demonstrated that RP in subsoils could also be altered by land-use change. In general, conversion from GS to CS decreased the recalcitrance index of SOC (RI_SOC), which increased after conversion from CS to WS. The results implied that cultivation decreased the stability of SOC, causing the depletion of SOC stock, whereas CS conversion to WS enhanced the stability of SOC, promoting SOC sequestration. The negative correlations between RI_SOC, pH, and electrical conductivity (EC_1:5) suggested that soil pH and salinity were potential indicators reflecting the biochemical recalcitrance of SOC. Since both soil pH and EC_1:5 showed decreasing trends after conversion from CS to WS and OS, the results suggested that afforestation on CS contributed to mitigate soil salinization while promoting SOC sequestration in this semi-arid agro-pastoral ecotone.

23616. 题目: Predicting the dry bulk density of soils across Denmark: Comparison of single-parameter, multi-parameter, and vis–NIR based models
文章编号: N19120102
期刊: Geoderma
作者: Sheela Katuwal, Maria Knadel, Trine Norgaard, Per Moldrup, Mogens H. Greve, Lis W. de Jonge
更新时间: 2019-12-01
摘要: Dry bulk density (BD) is a key soil physical property, characterizing the level of soil compaction and controlling flow and transport of fluids and solutes. In this study, predictive BD models were developed from 2462 BD measurements of mineral soils representing both top- and subsoil horizons across Denmark. Three types of BD models were compared: (i) single-parameter based on soil organic carbon (SOC), (ii) multi-parameters based on SOC, soil texture and depth, and using multiple linear regression (MLR), and (iii) visible–near infrared spectroscopy (vis–NIRS) based, using the spectral information and partial least squares regression (PLSR). Also, three machine learning techniques (random forest (RF), regression rules (RR), and artificial neural networks (ANN)) were applied for multi-parameter and vis–NIRS based models to potentially improve predictions. BD models were calibrated on 70% of dataset and validated on the remaining 30%. Single-parameter models with SOC had the lowest predictive potential and were not able to predict BD above 1.62 g cm⁻³. Machine learning using RF, RR and ANN on soil properties resulted in significantly higher prediction accuracies (RMSE ≤ 0.11 g cm⁻³ and R² ≥ 0.60) than MLR (RMSE = 0.12 g cm⁻³ and R² = 0.41) and SOC-based models. The relative importance of variables was obtained from the multi-parameter models with SOC and clay as the most important variables. The prediction accuracies MLR and vis–NIRS did not differ but were better than SOC-based models, suggesting that vis–NIRS could be a cost- and time-efficient alternative to pedotransfer functions that generally require determination of one or more soil properties for developing the calibration models. Decomposing the spectral data into principal components and using selected components as inputs for RF, RR and ANN improved the model performances only for RF models. Instead and in perspective, combining techniques by supplementing spectral data with readily available soil information and using machine learning techniques may further improve BD predictions.

23617. 题目: Predicting the Climate Change Impacts on Water-carbon Coupling Cycles for a Loess Hilly-gully Watershed
文章编号: N19120101
期刊: Journal of Hydrology
作者: Fubo Zhao, Yiping Wu, Yingying Yao, Ke Sun, Xuesong Zhang, Leigh Winowiecki, Tor-G. Vågen, Jianchu Xu, Linjing Qiu, Pengcheng Sun, Yuzhu Sun
更新时间: 2019-12-01
摘要: Understanding the climate change impacts on water and carbon cycles is of great importance for comprehensive watershed management. Although many studies have been conducted on the future climate change impacts on either water cycle or carbon cycle, the potential impacts on water-carbon coupling cycles are still poorly understood. This study used an integrated hydro-biochemical model (SWAT-DayCent) to quantitatively investigate the climate change impacts on water-carbon coupling cycles with a case study a typical loess hilly-gully watershed-the Jinghe River Basin (JRB) on the Loess Plateau. We used climate scenarios data derived under the three Representative Concentration Pathways (RCPs2.6, 4.5 and 8.5) by five downscaled Global Circulation Models (GCMs) and set two future periods of 2020-2049 (near future, NF) and 2070-2099 (far future, FF). It was projected that the annual precipitation would generally decrease slightly during the NF period but increase by 4-11% during the FF period, while the maximum/minimum air temperatures would increase significantly. The average annual streamflow would decrease (with up to 20.1% under RCP8.5) and evapotranspiration (ET) would remain almost unchanged during the NF period; however, both of them would increase during the FF period. The net primary production (NPP) would be generally higher due to the CO₂ fertilization, whereas the soil organic carbon would decrease across all scenarios due to the warmer climate. The NPP-ET was projected to be closely coupled across all scenarios, and this coupling was mainly controlled by the inter-annual variability (IAV) of precipitation. Moreover, the precipitation IAV combined with NPP-ET coupling could also jointly control the NPP variability in the JRB. These projections in water-carbon coupling cycles can be useful to make better-informed decisions for future water resources and ecosystem management of the loess hilly-gully regions.

23618. 题目: Long‐term surface application of dairy liquid manure to soil under no‐till improves carbon and nitrogen stocks
文章编号: N19113005
期刊: European Journal of Soil Science
作者: J. S. Cavalcante, N. Favaretto, J. Dieckow, V. F. Cherobim, G. Barth
更新时间: 2019-11-30
摘要: Manure application and no‐till management improves soil quality, crop yields and C inputs, but little specific knowledge is available regarding the effect of the combined effect of long‐term dairy liquid manure (DLM) application and no‐till management on soil organic matter status and soil structure in top soils. Here, we assess the impacts of surface‐applied DLM for ten‐year period on soil total organic carbon (TOC) and nitrogen (TN) concentrations and stocks, on organic matter fractions and on soil physical‐structural attributes in a no‐till crop rotation system on clayey Ferralsol under no‐till crop rotation management in a subtropical climate. Four rates of DLM (0, 60, 120 and 180 m³ ha^‐1 year^‐1) were applied in a randomized block design with four replications. Soil samples were collected to calculate TOC and TN stocks to 100 cm depth and organic matter fractions in the 0‐5 cm layer, and physical indicators of soil quality: bulk density, macroporosity and microporosity and aggregate stability. The largest DLM rates (120 and 180 m³ ha^‐1 year^‐1) added 3.8‐5.8 Mg C ha^‐1 year^‐1 as manure, increased crop residue input by 0.6 Mg C ha^‐1 year^‐1, and increased TOC stock by 17% and TN stock by 27% in the top 10 cm soil, at annual accumulation rates that averaged 0.72 Mg C ha^‐1 year^‐1 and 86 kg N ha^‐1 year^‐1. Stocks of TOC and TN in the sand‐POM (particulate organic matter) fraction under the 180 m³ ha^‐1 year^‐1 rate increased by 49 and 63%, and in the silt‐MOM (mineral‐associated organic matter) fraction by 30 and 47%, respectively. In the clay‐MOM fraction, the change in TOC were not significant, but the TN increased by 16%. Soil physical‐structural attributes (bulk density, porosity and aggregates) were improved by DLM application in the 10 cm layer and followed the soil carbon and nitrogen increments. Overall, the DLM amendment applied on the soil surface of no‐till proved to be a strategy to ameliorate soil organic matter status, an important factor for agronomic and environmental benefits; besides improving crop biomass production.

23619. 题目: Potential feedback mediated by soil microbiome response to warming in a glacier forefield
文章编号: N19113004
期刊: Global Change Biology
作者: Yuwan Wang, Anzhou Ma, Guohua Liu, Jianpeng Ma, Jing Wei, Hanchang Zhou, Kristian Koefoed Brandt, Guoqiang Zhuang
更新时间: 2019-11-30
摘要: Mountain glaciers are retreating at an unprecedented rate due to global warming. Glacier retreat is widely believed to be driven by the physiochemical characteristics of glacier surfaces; however, the current knowledge of such biological drivers remains limited. An estimated 130 Tg of organic carbon (OC) is stored in mountain glaciers globally. As a result of global warming, the accelerated microbial decomposition of OC may further accelerate the melting process of mountain glaciers by heat production with the release of greenhouse gases, such as carbon dioxide (CO₂) and methane. Here, using short‐term aerobic incubation data from the forefield of Urumqi Glacier No. 1, we assessed the potential climate feedback mediated by soil microbiomes at temperatures of 5°C (control), 6.2°C (RCP 2.6), 11°C (RCP 8.5), and 15°C (extreme temperature). We observed enhanced CO₂–C release and heat production under warming conditions, which led to an increase in near‐surface (2 m) atmospheric temperatures, ranging from 0.9°C to 3.4°C. Warming significantly changed the structures of the RNA‐derived (active) and DNA‐derived (total) soil microbiomes, and active microbes were more sensitive to increased temperatures than total microbes. Considering the positive effects of temperature and deglaciation age on the CO₂–C release rate, the alterations in the active microbial community structure had a negative impact on the increased CO₂–C release rate. Our results revealed that glacial melting could potentially be significantly accelerated by heat production from increased microbial decomposition of OC. This risk might be true for other high‐altitude glaciers under emerging warming, thus improving the predictions of the effects of potential feedback on global warming.

23620. 题目: Anhydrosugars as tracers in the Earth system
文章编号: N19113003
期刊: Biogeochemistry
作者: Loredana G. Suciu, Caroline A. Masiello, Robert J. Griffin
更新时间: 2019-11-30
摘要: Wild and prescribed fires are important sources of a broad suite of organic compounds collectively termed pyrogenic carbon (PyC). Most PyC compounds have additional sources beyond fire, adding uncertainty to their use as tracers. However, members of the anhydrosugar family of isomeric compounds—levoglucosan, galactosan and mannosan—are generated exclusively by the pyrolysis and combustion of cellulose and hemicellulose. Although anhydrosugars are some of the only unique organic markers for fire, they have not yet seen wide use as tracers in terrestrial or marine research because our understanding of their biogeochemistry and transport through the Earth system is poorly constrained. Anhydrosugars are chemically reactive in all phases (gaseous, aqueous and particulate), molecularly diffusive in semisolid matter, semivolatile, water-soluble, and biodegradable. Their chemical composition also suggests that they sorb to soil mineral surfaces. Together, these characteristics mean that anhydrosugars are not conservative tracers. While these traits have historically been perceived as drawbacks, here we argue that these characteristics present opportunities for new research avenues, including tracking organic matter transport and degradation in multiple environments. We review evidence for anhydrosugar production, degradation and detection in various environments, and use this information to propose new research on PyC and organic matter in the Earth system.