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23661. 题目: Silicon fertilizer and biochar effects on plant and soil PhytOC concentration and soil PhytOC stability and fractionation in subtropical bamboo plantations
文章编号: N20020503
期刊: Science of The Total Environment
作者: Chengpeng Huang, Li Wang, Xiaoqiang Gong, Zhangting Huang, Miaorong Zhou, Jiong Li, Jiasen Wu, Scott X. Chang, Peikun Jiang
更新时间: 2020-02-05
摘要: The use of exogenous silicon (Si) amendments, such as Si fertilizers and biochar, can effectively increase crop Si uptake and the formation of phytoliths, which are siliceous substances that are abundant in numerous plant species. Phytolith-occluded carbon (C) (PhytOC) accumulation in soil plays an important role in long-term soil organic C (SOC) storage. Nevertheless, the effects of both Si fertilizer and biochar application on PhytOC sequestration in forest plant-soil systems have not been studied. We investigated the impact of Si fertilizer and biochar applications on 1) the PhytOC pool size, the solubility of plant and soil phytoliths, and soil PhytOC in soil physical fractions (light (LFOM) and heavy fractions of organic matter (HFOM)) in Moso bamboo (Phyllostachys pubescens) forests; and 2) the relationships among plant and soil PhytOC concentrations and soil properties. We used a factorial design with three Si fertilizer application rates: 0 (S0), 225 (S1) and 450 (S2) kg Si ha⁻¹, and two biochar application rates: 0 (B0) and 10 (B1) t ha⁻¹. The concentrations of PhytOC in the bamboo plants and topsoil (0–10 cm) increased with increasing Si fertilizer addition, regardless of biochar application. Biochar addition increased the soil PhytOC pool size, as well as the LFOM- and HFOM-PhytOC fractions, regardless of Si fertilizer application. The Si fertilizer application increased or had no effect on soil phytolith solubility with or without biochar application, respectively. Soil PhytOC was correlated with the concentration of soil organic nitrogen (R² = 0.32), SOC (R² = 0.51), pH (R² = 0.28), and available Si (R² = 0.23). Furthermore, Si fertilizer application increased plant and soil PhytOC by increasing soil available Si. Moreover, biochar application increased soil PhytOC concentration in LFOM-PhytOC and the unstable fraction of PhytOC. We conclude that Si fertilizer and biochar application promoted PhytOC sequestration in the plant-soil system and changed its distribution in physical fractions in the Moso bamboo plantation in subtropical China.
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23662. 题目: Biochar and magnetite promote methanogenesis during anaerobic decomposition of rice straw
文章编号: N20020502
期刊: Soil Biology and Biochemistry
作者: Junjie Huang, Ke Ma, Xingxuan Xia, Kailin Gao, Yahai Lu
更新时间: 2020-02-05
摘要: Conductive materials like magnetite nanoparticles (nanoFe₃O₄) are known to stimulate methanogenesis from syntrophic oxidation of butyrate and propionate. Whether conductive materials increase the decomposition of complex organic substrates like plant residues is unknown. Here, we investigated the effects of biochar and nanoFe₃O₄ on anaerobic decomposition of rice straw and methanogenesis in a rice paddy soil. The straw decomposition and CH₄ production were greatly stimulated by both treatments. Major bacterial populations were Bacteroidetes, Clostridia, Deltaproteobacteria, Actinobacteria and Anaerolineae, while methanogens were predominately Methanosarcina, Methanosaeta and Methanobacterium. Bacteroides were relatively enriched in the biochar treatment, while the Deltaproteobacteria and Anaerolineae were favored by nanoFe₃O₄. The relative abundance of typical syntrophs including Syntrophomonas, Syntrophus and Smithella were positively correlated with the degradation of intermediate short-chain fatty acids. Notably, the relative abundance of Geobacter, which increased during the incubation, was approximately tenfold greater than all other syntrophs. The co-occurrence of Geobacter together with Methanosarcina and Methanosaeta suggests that the enhanced decomposition of rice straw and methanogenesis by biochar and magnetite may be related to direct interspecies electron transfer involved in the syntrophic oxidation of intermediate products.

23663. 题目: Projecting competition between 2-methylisoborneol and natural organic matter in adsorption onto activated carbon from ozonated source waters
文章编号: N20020501
期刊: Water Research
作者: Qi Wang, Frederik Zietzschmann, Jianwei Yu, Roberta Hofman, Wei An, Min Yang, Luuk C. Rietveld
更新时间: 2020-02-05
摘要: Though the ozone-activated carbon process has been widely applied for drinking water purification, little is known about how ozone-modified natural organic matter (NOM) competes with micropollutants in activated carbon adsorption. In this study, three natural waters and one synthetic water (standard humics solution) with highly heterogeneous NOM compositions were employed to investigate the interference of ozonated NOM with the adsorption of 2-methylisoborneol (MIB). Analysis using liquid chromatography with online carbon and UV₂₅₄ detection (LC-OCD-UVD) revealed that ozonation led to various disintegration patterns of macromolecules in NOM, and UV absorbance was reduced markedly for nearly all NOM fractions. Powdered activated carbon (PAC) adsorption experiments showed that increasing ozone consumption coincided with reducing NOM competition against MIB in the three natural waters, as expressed by the fitted initial concentrations of the equivalent background compound (c_0,EBC). In the synthetic water, in contrast, competition increased under low/moderate specific ozone consumptions and then decreased with further elevation of ozone consumptions. Regarding the significance on affecting ozonated NOM interference, aromaticity reduction outweighed formation of low molecular weight (LMW) organics in most cases, enhancing MIB adsorption capacity. However, disintegration of the humics fraction with larger molecular weight (1,103 g/mol, as compared to 546–697 g/mol in three natural waters) into smaller, more competitive fractions caused the observed initial deteriorated MIB adsorption in synthetic water. A superior correlation between c_0,EBC and the UV absorbance of LMW organics (R² = 0.93) over concentrations of LMW organics underlined the importance of the aromatic properties in competitive adsorption projection for ozone pretreated natural waters. Furthermore, the change of relative concentration of UV absorbing compounds during ozonation could help estimate the decrease of c_0,EBC, which could be a promising tool for waterworks to adjust PAC doses for MIB removal in ozonated waters.
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23664. 题目: Characterization of Carbonyl Disinfection By-Products During Ozonation, Chlorination, and Chloramination of Dissolved Organic Matters
文章编号: N20020410
期刊: Environmental Science & Technology
作者: Xueke Liu, Ruirui Liu, Bao Zhu, Ting Ruan, Guibin Jiang
更新时间: 2020-02-04
摘要: Carbonyl compounds are an important class of by-products that are generated in disinfection reactions. These chemicals are ingredients contributing to toxicology in the drinking water system, the compositions and structures of which are worthy of attention. In this study, a chemical derivatization method based on simultaneous light/heavy isotope labeling was established for general recognition of carbonyl compounds and carbonyl disinfection by-products (DBPs) as per the humic substance reference standard (Suwannee river fulvic acid II, SRFA) before and after ozonation, chlorination, and chloramination. Decomposition of macromolecular components into polar carbonyl species was observed to be the most prominent pathway in ozone treatment due to the efficient reactivity of ozone with phenols and alkoxy aromatic rings. As a result, alteration of molecular characteristics was noticed. For instance, ozone-induced carbonyl DBPs in the highly oxygenated compound classes (0.67 ≤ O/C ≤ 1.2, 0.6 < H/C ≤ 1.5) possessed higher O/C but contained less oxygen numbers and carbon numbers. Cl/Br-carbonyl-DBPs were identified after chlorination and chloramination, and I-carbonyl-DBPs were found in ozone and chloramine treatments. Several major halogenated carbonyl homologues were further recognized, including halogenated 4-oxobutenoic acid analogues, halogenated 2,5-dioxohex-3-enoic acid analogues, and halogenated 4-cyclopentene-1,3-diones analogues. These findings illustrate the presence of abundant carbonyl DBPs in water disinfection, and hence their impacts on human health deserve further investigation.

23665. 题目: Performance of the emerging biochar on the stabilization of potentially toxic metals in smelter- and mining-contaminated soils
文章编号: N20020409
期刊: Environmental Science and Pollution Research
作者: Chunyan Ren, Di Guo, Xiangyu Liu, Ronghua Li, Zengqiang Zhang
更新时间: 2020-02-04
摘要: Soil potentially toxic metals (PTMs) pollution caused by anthropogenic activities has become serious concern with respect to the crop safety production. In this study, an emerging biochar derived from kiwi pruning branches waste was employed as amendment aiming to evaluate its remediation potential on smelter- and mining-contaminated soils. The effect of biochar on the soil physicochemical properties, leachability, and chemical fractions acted on stabilization practice of PTMs in soil was investigated. The results showed that the addition of biochar increased the soil pH, cation exchange capacity, organic matter, and enzymatic activities (dehydrogenase, urease, and sucrase) but reduced the extraction toxicity of PTMs in both smelter (Fengxian, FX) and mining (Tongguan, TG) soils. The fraction analysis showed that the maximum reduction of exchangeable fraction of Cd, Zn, and Pb in the 4% biochar amended soils decreased by 11.1, 13.3, and 24.7% in FX soil and 7.67, 22.8, and 7.89% in TG soil, respectively, in comparison with to control (no biochar added). Additionally, the residual fraction of Cd, Zn, and Pb increased by 55.9, 7.14, and 11.0% in FX soil and 23.7, 5.86, and 10.0% in TG soil, respectively. The further greenhouse experiment showed that the Indian mustard (Brassica juncea) production increased with the increasing application dosages of biochar, while the PTMs uptakes in plant notably decreased after amendments. Conversion of kiwi pruning branches waste into emerging biochar benefits the agricultural waste recycling utilization and enhances PTMs-contaminated soil remediation in practice.

23666. 题目: Isotope alteration caused by changes in biochemical composition of sedimentary organic matter
文章编号: N20020408
期刊: Biogeochemistry
作者: Xiaoqing Liu, Liane Hilfert, Johannes A. C. Barth, Robert van Geldem, Kurt Friese
更新时间: 2020-02-04
摘要: Stable carbon (C) and nitrogen (N) isotope ratios of sedimentary organic matter (OM) can reflect the biogeochemical history of aquatic ecosystems. However, diagenetic processes in sediments may alter isotope records of OM via microbial activity and preferential degradation of isotopically distinct organic components. This study investigated the isotope alteration caused by preferential degradation in surface sediments sampled from a eutrophic reservoir in Germany. Sediments were treated sequentially with hot water extraction, hydrochloric acid hydrolysis, hydrogen peroxide oxidation and di-sodium peroxodisulfate oxidation to chemically simulate preferential degradation pathways of sedimentary OM. Residue and extracts from each extraction step were analyzed using elemental analyzer-isotope ratio mass spectrometry and solid-state ¹³C nuclear magnetic resonance spectroscopy. Our results show that stable C and N isotope ratios reacted differently to changes in the biochemical composition of sedimentary OM. Preferential degradation of proteins and carbohydrates resulted in a 1.2‰ depletion of ¹³C, while the isotope composition of ¹⁵N remained nearly the same. Sedimentary δ¹⁵N values were notably altered when lignins and lipids were oxidized from residual sediments. Throughout the sequential fractionation procedure, δ¹³C was linearly correlated with the C:N of residual sediments. This finding demonstrates that changes in biochemical composition caused by preferential degradation altered δ¹³C values of sedimentary OM, while this trend was not observed for δ¹⁵N values. Our study identifies the influence of preferential degradation on stable C isotope ratios and provide additional insight into the isotope alteration caused by post-depositional processes.

23667. 题目: Application of hybrid ANN-whale optimization model in evaluation of the field capacity and the permanent wilting point of the soils
文章编号: N20020407
期刊: Environmental Science and Pollution Research
作者: Babak Vaheddoost, Yiqing Guan, Babak Mohammadi
更新时间: 2020-02-04
摘要: Field capacity (FC) and permanent wilting point (PWP) are two important properties of the soil when the soil moisture is concerned. Since the determination of these parameters is expensive and time-consuming, this study aims to develop and evaluate a new hybrid of artificial neural network model coupled with a whale optimization algorithm (ANN-WOA) as a meta-heuristic optimization tool in defining the FC and the PWP at the basin scale. The simulated results were also compared with other core optimization models of ANN and multilinear regression (MLR). For this aim, a set of 217 soil samples were taken from different regions located across the West and East Azerbaijan provinces in Iran, partially covering four important basins of Lake Urmia, Caspian Sea, Persian Gulf-Oman Sea, and Central-Basin of Iran. Taken samples included portion of clay, sand, and silt together with organic matter, which were used as independent variables to define the FC and the PWP. A 80–20 portion of the randomly selected independent and dependent variable sets were used in calibration and validation of the predefined models. The most accurate predictions for the FC and PWP at the selected stations were obtained by the hybrid ANN-WOA models, and evaluation criteria at the validation phases were obtained as 2.87%, 0.92, and 2.11% respectively for RMSE, R², and RRMSE for the FC, and 1.78%, 0.92, and 10.02% respectively for RMSE, R², and RRMSE for the PWP. It is concluded that the organic matter is the most important variable in prediction of FC and PWP, while the proposed ANN-WOA model is an efficient approach in defining the FC and the PWP at the basin scale.

23668. 题目: Molecular characterization of soil organic carbon in water-stable aggregate fractions during the early pedogenesis from parent material of Mollisols
文章编号: N20020406
期刊: Journal of Soils and Sediments
作者: Na Li, Jinghong Long, Xiaozeng Han, Yaru Yuan, Ming Sheng
更新时间: 2020-02-04
摘要: Purpose: The aims of this study were to investigate how short-term agricultural practices varying in vegetation cover, tillage, and organic amendments affected the chemistry of aggregate-associated C and particulate organic matter (POM) after 8-year soil restoration from parent material (PM) of a Mollisol. The research allowed indicating the effects of perennialization and organic amendments on the chemical compositions of soil organic carbon (SOC) in both aggregates and POM in short-term and thereof helped to unveil the mechanisms of C sequestration and stabilization. Material and methods: The field surface soils (0–20 cm) under 8-year natural perennials and an arable soil with organic amendments were collected. Soil aggregate fractionation method was applied to obtain three aggregate-sized fractions: macroaggregate (> 250 μm), microaggregate (53–250 μm), and silt-clay unit (< 53 μm). The coarse POM (cPOM, > 250 μm), microaggregate (53–250 μm), and silt-clay units within macroaggregate, the fine POM (fPOM, 53–250 μm), and silt-clay units within microaggregate were further separated. In all, 10 subgroups of aggregates were obtained to determine organic carbon content and chemical structure using ¹³C-NMR spectroscopy technique. The PM for the establishment of the experiment was also used. Results and discussion: The chemical composition of SOC differed among aggregate sizes, representing different organic compositions with different decomposition stages. Compared with PM, soil restoration under natural perennial and organic amendments increased SOC in both POM and aggregate fractions; higher proportion of POM with larger proportion of plant-derived O-alkyl C was observed in arable soil than in perennials. Meanwhile, the silt-clay units, sequestrating the most of the organic C, contained larger proportions of alkyl C, aromatic C, and carbonyl C, probably due to the microbial-derived by-products. The data partially supported our hypothesis that continuous organic amendments to PM likely promoted aggregate formation and subsequently affected the chemical composition of C therein. Conclusions: Perennialization and organic amendments increased not only the total SOC stocks in bulk soils and aggregate fractions but also changed the SOM chemistry by varying quantity and quality of plant residues. The silt-clay units contributed largely to the stock and stability of SOC during the soil development stage from PM of a Mollisol. The main mechanisms of plant-derived C sequestrated and SOC accrued were controlled probably not only by the physiochemical protection of soil aggregates but also by the microbial C sequestration capacity in silt-clay fraction at the initial stage of soil formation.

23669. 题目: Underway seawater and atmospheric measurements of volatile organic compounds in the Southern Ocean
文章编号: N20020405
期刊: Biogeosciences
作者: Charel Wohl, Ian Brown, Vassilis Kitidis, Anna E. Jones, William T. Sturges, Philip D. Nightingale, and Mingxi Yang
更新时间: 2020-02-04
摘要: Dimethyl sulfide and volatile organic compounds and are important for atmospheric chemistry. The oceanic emissions of biogenically derived gases, including dimethyl sulfide and especially isoprene, are not well constrained. The role of the ocean in the global budgets of atmospheric methanol, acetone and acetaldehyde is even more poorly known. In order to quantify the air-sea fluxes of these gases we measured their seawater concentrations and air mixing ratios in the Atlantic sector of the Southern Ocean, along a ~ 11 000 km long transect at approximately 60° S in Feb–Apr 2019. Concentrations, oceanic saturations and estimated fluxes of several simultaneously sampled volatile organic compounds (methanol, acetone, acetaldehyde, dimethyl sulfide and isoprene) are presented here. Campaign mean (± 1σ) surface water concentrations of dimethyl sulfide, isoprene, methanol, acetone and acetaldehyde were 2.60 (± 3.94), 0.0133 (± 0.0063), 67 (± 35), 5.5 (± 2.5) and 2.6 (± 2.7) nmol dm⁻³ respectively. In this dataset, seawater isoprene and methanol concentrations correlated positively. Furthermore, seawater acetone, methanol and isoprene concentrations were found to correlate negatively with the fugacity of carbon dioxide, possibly due to a common biological origin. Campaign mean (± 1σ) air mixing ratios of methanol, acetone and acetaldehyde were relatively low at 0.17 (± 0.08), 0.081 (± 0.031) and 0.049 (± 0.040) ppbv. We observed diel changes in averaged acetaldehyde concentrations in seawater and ambient air (and to a lesser degree also for acetone and isoprene), which suggest light-driven productions. Campaign mean (± 1σ) fluxes of 4.3 (± 7.4) µmol m⁻² d⁻¹ DMS and 0.028 (± 0.021) µmol m⁻² d⁻¹ isoprene are determined where a positive flux indicates from the ocean to the atmosphere. Methanol was largely undersaturated in the surface ocean with a mean (± 1σ) net flux of −2.4 (± 4.7) µmol m⁻² d⁻¹, but also had a few occasional episodes of outgassing This section of the Southern Ocean was found to be both a source and a sink for acetone and acetaldehyde this time of the year, depending on location, resulting in a mean flux of −0.55 (± 1.15) µmol m⁻² d⁻¹ for acetone and −0.28 (± 1.22) µmol m⁻² d⁻¹ for acetaldehyde. The data collected here will be important for constraining the oceanic source/sink of these gases and potentially help to elucidate the presence of common sources/sinks for these compounds.

23670. 题目: Atmospheric deposition of organic matter at a remote site in the Central Mediterranean Sea: implications for marine ecosystem
文章编号: N20020404
期刊: Biogeosciences
作者: Yuri Galletti, Silvia Becagli, Alcide di Sarra, Margherita Gonnelli, Elvira Pulido-Villena, Damiano M. Sferlazzo, Rita Traversi, Stefano Vestri, and Chiara Santinelli
更新时间: 2020-02-04
摘要: Atmospheric fluxes of dissolved organic matter (DOM) were studied for the first time at the Island of Lampedusa, a remote site in the Central Mediterranean Sea (Med Sea), close to the Sahara desert, between 19 March 2015 and 1 April 2017. The main goals of this work are: to quantify total atmospheric deposition of DOM in this area and to evaluate the impact of dust deposition on DOM dynamics in the surface waters of the Mediterranean Sea. Our data show high variability in DOM deposition rates without a clear seasonality and allow to estimate a dissolved organic carbon (DOC) input from the atmosphere of 120.7 mmol DOC m⁻² yr⁻¹. Over the entire time-series, the average dissolved organic phosphorous (DOP) and dissolved organic nitrogen (DON) contributions to the total dissolved pools were 40 % and 26 %, respectively. The data on atmospheric elemental ratios also show that each deposition event is characterized by a specific elemental ratio, suggesting a high variability in DOM composition and the presence of multiple sources. This study indicates that the organic substances transported by Saharan dust at Lampedusa site mainly have natural origin, especially from sea spray and that Saharan dust can be an important carrier of organic substances, even if the load of DOC associated with dust is highly variable. Our estimates suggest that atmospheric input has an impact to the Med Sea larger than to the global ocean and that DOC fluxes from the atmosphere to the Med Sea can be up to 6-fold larger than river input. Longer time series, combined with a modelling effort, are therefore mandatory in order to investigate the response of DOM dynamics in the Med Sea to the change in aerosol deposition pattern due to the effect of climate change.

23671. 题目: Formation of free radicals by direct photolysis of halogenated phenols (HPs) and effects of DOM: A case study on monobromophenols
文章编号: N20020403
期刊: Journal of Hazardous Materials
作者: Jingqiu Jiang, Hongxia Zhao, Deming Xia, Xintong Li, Baocheng Qu
更新时间: 2020-02-04
摘要: The free radicals play an important role to understand direct/indirect transformation mechanisms of organic pollutants. However, very few efforts have been made to elucidate the radicals produced by direct photolysis. In this study, the short-lived radicals generated under simulated sunlight irradiation from representative halogenated phenols (HPs), monobromophenols, were investigated by electron paramagnetic resonance (EPR). The results showed that three radicals, carbon-centered radical (·C), hydrogen radical (·H) and hydroxyl radical (·OH), were generated from the direct irradiation of HPs. Compared to other substitutions, halogenated atom at para-position led to the highest production of these radicals which is in accordance with the energies calculated by density functional theory. Based on the analyses of the reactive species and corresponding intermediate adducts, the possible reaction pathways for these radicals were tentatively proposed. Dissolved organic matters (DOM) could enhance the photodegradation of HPs by directly affecting the radicals’ formation, mainly due to generation of excited triplet DOM (³DOM*). A positive correlation was found between the concentrations of hydrated electron and the steady state ³DOM* from different DOM. Our findings provided insights into environmental photochemical fate of HPs through their direct photolysis and will help more accurately understand their phototransformation mechanisms in the environment.
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23672. 题目: Facile magnetic biochar production route with new goethite nanoparticle precursor
文章编号: N20020402
期刊: Science of The Total Environment
作者: Divine Damertey Sewu, Hai Nguyen Tran, Godfred Ohemeng-Boahen, Seung Han Woo
更新时间: 2020-02-04
摘要: This study fabricated a green and novel magnetic biochar via the co-pyrolysis of firwood biomass pre-treated with 10% (w/w) of either solid- (admixing; G10BC_A) or liquid-phase (impregnation; G10BC_I) goethite mineral (α-FeOOH). Newly fabricated magnetic biochars were characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES), Brunauer-Emmett-Teller (BET) equipment, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), proximate and elemental analyzer, and vibrating sample magnetometry. The effects of magnetic precursor, iron loading, and aqua-treatments on recoverability, magnetic properties, and stability (resistance to α-FeOOH reconstructive crystallization/dissolution reactions) were found and compared to those of magnetic biochar derived from conventional ferric chloride precursors (F10BC_I). Results confirmed a direct correlation between biochar yields and ash contents with iron loading, irrespective of the magnetic precursor type. Despite the higher total carbon content (83.6% (w/w)) and surface area (299 m²/g) of F10BC_I, α-FeOOH proved to be more effective at yielding magnetic biochars with nanostructured surfaces, lower water extractable components (thus green; G10BC_A = 0.21 mg/mL; G10BC_I = 0.16 mg/mL), higher magnetic saturation (G10BC_A = 10.0 emu/g; G10BC_I = 20.8 emu/g), and ferromagnetic susceptibility as well as recoverability. Furthermore, α-FeOOH was undetected on the surface of G10BC_A, post-aqua-treatments (over 30 days), and this demonstrated its stability in the face of demagnetization via α-FeOOH reformation reactions. Consequently, this study showed that admixing solid-phase α-FeOOH (10% (w/w)) with firwood biomass offers a green, facile, and efficient way to thermochemically produce magnetic biochar. It has superb stability to α-FeOOH reconstructive crystallization/dissolution reactions in aqua media, green attributes, good magnetic properties, and great application potential in many areas of the economy.
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23673. 题目: Heavy metal pollution in a reforested mangrove ecosystem (Can Gio Biosphere Reserve, Southern Vietnam): Effects of natural and anthropogenic stressors over a thirty-year history
文章编号: N20020401
期刊: Science of The Total Environment
作者: Sandra Costa-Böddeker, Lê Xuân Thuyên, Philipp Hoelzmann, Henko C. de Stigter, Piet van Gaever, Hoàng Đức Huy, John P. Smol, Antje Schwalb
更新时间: 2020-02-04
摘要: In order to assess the impact of recent industrialization and land-use changes in the Can Gio Mangrove Forest, a Biosphere Reserve in Southern Vietnam, we analyzed heavy metal (HM), total organic carbon (TOC) and total nitrogen (TN) concentrations in a ²¹⁰Pb-dated sediment core, allowing for the environmental reconstruction of the last three decades. C/N ratios were very high (>20) until ~1990, reflecting highly refractory organic matter. Sediment Quality Guidelines (SQG's) violations were observed particularly after the establishment of industries in the area in the late-1990s. Chromium (Cr) and copper (Cu) exceeded the threshold effect levels (TEL); whereas nickel (Ni) was above the probable effects level (PEL), identifying the risk of potential adverse biological effects. Moderate contamination, mainly from cobalt (Co) and lead (Pb), was detected by the contamination factor (CF) index, with Pb levels likely originating from mainly anthropogenic sources, particularly after ~1992, as indicated by elevated enrichment factor (EF) values. A high positive correlation was found between Pb, Cr, Cu and Ni (r ≥ 0.8), while Co, cadmium (Cd) and TOC were highly positive correlated (r = 0.9). We identified evidence of point sources, atmospheric pollution and erosion as the main contributors to enhanced HM levels. However, negative values of the Geo-accumulation index (I-geo) indicated uncontaminated sediments. This discrepancy in pollution indices was likely due to the use of shale averages instead of regional levels as background values, as well as the influence of multiple stressors.
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23674. 题目: A 50-year sediment record of algal assemblage changes in Hanabanilla Reservoir, Cuba
文章编号: N20020305
期刊: Journal of Paleolimnology
作者: Yeny Labaut, Pablo A. Macchi, Augusto A. Comas, Carmen R. Betancourt, Misael Díaz-Asencio
更新时间: 2020-02-03
摘要: Hanabanilla Reservoir, south-central Cuba, is used for electric power generation, potable water supply and tourism. We examined stratigraphic shifts in algal assemblages that accumulated in the reservoir sediments from the time of construction in 1960 through 2012, and inferred the environmental drivers of such biological changes. Historical fluctuations in algal assemblages were driven by scouring of the reservoir bottom, changing water level, and input of organic matter and nitrogen to the water body. Stage records, in conjunction with algal counts, confirm the importance of the pennate/centric diatom ratio for reconstructing past water-level changes. Although nutrient and organic matter inputs to the reservoir also influenced algal abundance and community composition, our findings suggest that regulating reservoir hydrology could be an effective strategy for preventing future cyanobacterial blooms. Shifts in the relative abundances of algal taxa, and dominance of R strategists associated with extreme fluctuations in water level, showed the strong influence of hydrology as a determinant of primary producer assemblage structure.

23675. 题目: Effects of biochar particle size and concomitant nitrogen fertilization on soil microbial community structure during the maize seedling stage
文章编号: N20020304
期刊: Environmental Science and Pollution Research
作者: Rudong Zhao, Jiaping Wu, Canlan Jiang, Feng Liu
更新时间: 2020-02-03
摘要: Biochar is widely used as a soil amendment, either alone or in association with fertilizer. However, the effects of biochar particle size on the soil microbial community are largely unclear. Biochar was divided into two groups according to diameter sizes: < 1 mm and 2.5–5 mm (labeled as CB1 and CB5, respectively). A pot experiment was established in which maize (Zea maize L.) was treated with CB1, CB5, and/or external nitrogen (N, NH₄NO₃). At the end of the seedling period (45 days), analyses of soil microbial community structure and other soil and crop properties were conducted. The biochar (regardless of N addition) enhanced microbial biomass and activity. CB1 had a stronger capacity than CB5 to modify soil microbial community structure by promoting soil microbial groups (e.g., fungi, Gram-negative bacteria), which is likely due to CB1 undergoing a series of more intense processes (e.g., nutrient release, mineralization) than CB5. However, this difference was diminished or disappeared when N was added, mainly due to the masking effect of soil acidification that was induced by N fertilization. Collectively, fine biochar has a stronger effect on soil microbial community than coarse biochar. Particle size only affects soil microbial community structure when biochar is applied alone; it has no effect when biochar is applied in association with chemical N fertilizer, at least during the seedling period. The relationship between particle size and soil microbial community needs to be considered when using biochar for soil amendment.

23676. 题目: Increasing the methane production rate of hydrogenotrophic methanogens using biochar as a biocarrier
文章编号: N20020303
期刊: Bioresource Technology
作者: Hao-Jie Yang, Zhi-Man Yang, Xiao-Hui Xu, Rong-Bo Guo
更新时间: 2020-02-03
摘要: The existence of CO₂ in biogas will affect its practicality, so the methanation of CO₂ is of great significance. Carrier materials play a key role in bioconversion of CO₂ to methane during biogas upgrading. Herein, different materials were used to evaluate the bioconversion process of CO₂ to methane, which consisted of black ceramsite (BC) and biochars prepared from corn straw and digestate. The results showed that after adding the carrier materials, the methane production rate increased by more than 20%, and the corn straw biochar (CSB) group even increased by more than 70%. This may be attributed to the large specific surface area and more functional groups in corn straw biochar which was suitable for the immobilization of hydrogenotrophic methanogens (HMs). Therefore, corn straw biochar is a good carrier material for the accelerated bioconversion of CO₂ to methane.
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23677. 题目: Exploring the potential of airborne hyperspectral image for estimating topsoil organic carbon: Effects of fractional-order derivative and optimal band combination algorithm
文章编号: N20020302
期刊: Geoderma
作者: Yongsheng Hong, Long Guo, Songchao Chen, Marc Linderman, Abdul M. Mouazen, Lei Yu, Yiyun Chen, Yaolin Liu, Yanfang Liu, Hang Cheng, Yi Liu
更新时间: 2020-02-03
摘要: Estimating soil organic carbon (SOC) in topsoil can help improve soil quality and food production. This study aimed to explore the potential of airborne hyperspectral image to estimate the SOC of bare topsoil at an agricultural site located in the southeast part of Iowa State, United States. To magnify the subtle spectral signals concerning SOC, and accelerate calibration and improve predictive ability, we developed a framework to combine two advanced spectral algorithms, namely, fractional-order derivative (FOD) and optimal band combination algorithm for SOC predicting. Our case was based on 49 soil samples and a scattered airborne hyperspectral image. Random forest (RF) was utilized to establish SOC estimation models by incorporating the optimal spectral indices processed by different FOD transformations on the basis of the optimal band combination algorithm. Results indicated that when the fractional order increased, overlapping peaks and baseline drifts were gradually removed. However, the magnitude of spectral strength decreased concurrently. More detailed and abundant spectral variability was captured by FOD as compared with those by original reflectance and first and second derivatives. The estimation accuracies developed from the optimal band combination algorithm (cross-validation R², 0.36–0.66) were generally better than those from full-spectrum data (cross-validation R², 0.32–0.54). The RF model based on the combination of 0.75-order reflectance and optimal band combination algorithm obtained the highest estimation accuracy for SOC with cross-validation R² of 0.66. This research provides guidance for future studies in selecting the most appropriate FOD transformation to preprocess spectral data and in using the optimal band combination algorithm to determine the spectral index. Airborne hyperspectral image-based modeling can be further used to map agricultural topsoil SOC to support local-scale agricultural planning.

23678. 题目: Joint effect of nanoplastics and humic acid on the uptake of PAHs for Daphnia magna: A model study
文章编号: N20020301
期刊: Journal of Hazardous Materials
作者: Wei Lin, Ruifen Jiang, Xiaoying Xiao, Jiayi Wu, Songbo Wei, Yan Liu, Derek C.G. Muir, Gangfeng Ouyang
更新时间: 2020-02-03
摘要: Nanoplastics (NPs) are emerging pollutants which can adsorb large amounts of hydrophobic organic compounds (HOCs) and be ingested by aquatic organisms. NPs interact with dissolved organic matter (DOM) and result in significant impacts on the bioaccumulation of HOCs in the actual environment. For the first time, the joint effects of two complex matrices on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) to Daphnia magna (D. magna) were studied by modeling calculation. The complex matrices, nano-sized polystyrene (PS) and/or humic acid (HA), were under environmentally realistic concentrations. A biodynamic model was modified and the uptake fluxes from all exposure pathways were quantified using the experimental data. A flux estimation showed that the bioaccumulation amounts at equilibrium were mostly dependent on dermal uptake (≥99.3% of the total). The PS matrix would retard the intestinal uptake process in D. magna, especially for the less hydrophobic PAHs; while the HA or the HA-PS matrix would facilitate the mass transfer of PAHs from the matrix to lipids in the gut. Moreover, the biota matrix accumulation factor (BMAF) were calculated to verify the biodynamic model. This work is helpful to clarify the bioaccumulation effects of PAHs in complex environmental systems.
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23679. 题目: Accumulation and ecological risk of heavy metals in soils along the coastal areas of the Bohai Sea and the Yellow Sea: A comparative study of China and South Korea
文章编号: N20020208
期刊: Environment International
作者: Peng Liu, Wenyou Hu, Kang Tian, Biao Huang, Yongcun Zhao, Xinkai Wang, Yunqiao Zhou, Bin Shi, Bong-Oh Kwon, Kyungsik Choi, Jongseong Ryu, Yong Chen, Tieyu Wang, Jong Seong Khim
更新时间: 2020-02-02
摘要: Soils in coastal areas of the land-sea interface are vulnerable to heavy metal (HM) accumulation and subsequently to human health risk. However, few studies have investigated the HM pollution and risk in soils along the coastal areas of the Yellow Sea Large Marine Ecosystem (YSLME), in an international perspective. This study is the first comprehensive work in the YSLME encompassing 122 coastal locations along the Bohai Sea (BS), Yellow Sea of China (YSC), and Yellow Sea of South Korea (YSK). Soil HM pollution showed great spatial variations cross the regions and countries. Accumulations of As, Cu, Pb, and Zn in the YSK were significantly higher than those in the BS and YSC (p < 0.05). Whilst the elevated Cd, Hg, and Ni in soils were found in the BS and YSC compared to those in the YSK (p < 0.05). Meantime, the assessment of ecological risk posed by HMs indicated higher potential risk in the BS than other coastal areas. In specific, Cd and Hg posed a higher risk in the BS and YSC, while As showed relatively high risk in the YSK, indicating site-dependent accumulation of HMs in soils. Soil pH and organic matter were found to be important factors affecting the HM accumulation in the study areas. Industrial activities are the major driving factors influencing spatial distributions of HMs, and such activities exhibited different degrees of influence across the sampling sites. Altogether, the results of present study first identified the bilateral characteristics of soil HM pollution along the entire coasts of the YSLME in a comprehensive manner in several aspects: (1) sources, (2) hot spots, (3) priority chemicals of concern, and (4) site-specific potential risk of the soil HMs. Overall, this study provides references and backgrounds for future environmental management strategies and aids in developing a bilateral government policy towards coastal pollution management of HMs from an international scale and perspective.
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23680. 题目: Effects of external additives: Biochar, bentonite, phosphate, on co-composting for swine manure and corn straw
文章编号: N20020207
期刊: Chemosphere
作者: Huanhuan Li, Tao Zhang, Daniel C.W. Tsang, Guoxue Li
更新时间: 2020-02-02
摘要: Composting is an acceptable and economically feasible process for recycling agricultural biomass waste. The addition of external additives to adjust the process of composting has been attracted lots of research attention. To investigate the effects of external additives on nutrients transformation process of composting, a laboratory reactors scale co-composting based on swine manure and corn straw (CK) with the additives of phosphate (MP), calcium bentonite (CB) and biochar (BC) were performed for 30 days. The results showed the addition of phosphate and biochar could contribute to accelerating temperature rise and shorten the thermophilic phase. The germination index (GI) of MP and BC achieved 180% and 150%, respectively. The excitation-emission matrix (EEM) demonstrated the intensities of the peak C (humic acids) of the MP treatment was 829.5, and the P_V,n/P_III,n value (9.59) of MP treatment was particularly higher compared to other three treatments according to the fluorescence regional integration (FRI) analysis. The Fourier Transform Infrared spectroscopy (FTIR) indicated the rate of decomposition of aliphatic C substances was higher than that of aromatic C substances. According to the X-ray diffraction (XRD) spectra results, characteristic peaks at both 16° and 22° were decreased, indicating cellulose and amorphous components were degraded. It further proved the formation of struvite component in MP treatment. Therefore, based on the maturity indicators, EEM and XRD results, phosphate is an efficient additive and recommended for swine manure and corn straw co-composting.
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