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41. 题目: Examining the correlation between quantifiable SVOCs and organic carbon content or particulate size in benthic sediments as a function of ocean stratum
文章编号: N20021503
期刊: Environmental Science: Processes Impacts
作者: Ochan Otim
更新时间: 2020-02-15
摘要: The raw analytical concentration values of semi-volatile organic compounds (SVOCs) in ocean sediments do not necessarily reflect the bioavailable fractions of SVOCs in the sediments due to factors such as the total organic carbon content of sediment (TOC) and the percentage of fine particles in sediments (% Fines) believe to affect the extraction efficiency of SVOCs from sediment. Corrective actions are therefore taken to minimize their influence on measurements. In doing so, a broad and uniform correlation is assumed between the ‘native’ levels of the SVOCs and TOC or %Fines across ocean strata. Not yet verified though is the validity of this blanket assumption. In this study, we examined the strength of the assumption using levels of DDTs, PAHs and PCBs in sediments from Santa Monica Bay (SMB) in California, USA. (The distribution patterns of these SVOCs in SMB are known and reproducible for quality assurance.) As our results show, a uniform correlation between SVOCs levels and TOC or %Fines across strata is mostly unsupported. For example, while PAHs and PCBs levels show negative correlation with TOC or % Fines, and only in canyon sediments, DDTs levels correlate positively with both TOC and %Fines across at least three strata. Furthermore, the distribution of PAH molecules appears to be controlled by molecular size with the smaller PAHs found almost exclusively in the canyons. Our findings here, being the first of its kind, suggest that more work is actually needed to clarify the reporting of SVOCs levels in ocean sediments.

42. 题目: Spatiotemporal distribution, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the urbanized semi-enclosed Jiaozhou Bay, China
文章编号: N20021502
期刊: Science of The Total Environment
作者: Yuanxin Cao, Ming Xin, Baodong Wang, Chunye Lin, Xitao Liu, Mengchang He, Kai Lei, Ling Xu, Xuan Zhang, Shuang Lu
更新时间: 2020-02-15
摘要: Coastal contamination by polycyclic aromatic hydrocarbons (PAHs) is a worldwide issue. Nevertheless, the spatiotemporal distribution of PAHs in the urbanized semi-enclosed bays in China remains relatively uncharacterized. Here we present measurements of 15 priority PAHs in the water and sediment of the Jiaozhou Bay, as well the assessment of their spatiotemporal distribution, sources and ecological risk. The total PAH (ΣPAH) concentrations ranged from 23.6 to 86.2 ng L −1 in the water and from 37.7 to 290.9 ng g−1 in the sediment. The average ΣPAH concentration in the water was significantly higher in the winter (52.8 ng L −1) than in the spring (30.4 ng L −1) (α = 0.05 level). Average concentration of phenanthrene in the water was 8.9 ng L−1 in the spring and 15.7 ng L−1 in the winter and the highest of PAHs, contributing about 29.4% to ΣPAHs. Compared with three-ring PAHs, four- and five-ring PAHs were more tended to accumulate in the sediment, and the partitioning into sediment was influenced by the water salinity. The spatial distribution of ΣPAH concentrations in the water were controlled by water exchange capability. Organic matter content and sediment texture played important roles in determining the spatial distribution of ΣPAHs in the sediment. Molecular diagnostic ratio analysis indicated that pyrogenic source was the main source for PAHs in the Bay. Specifically, the positive matrix factorization (PMF) model indicated that vehicle emission, biomass combustion, coal combustion, and petrogenic sources contributed for 41.6, 20.2, 20, and 18.2% of ΣPAHs, respectively. The risk assessment by sediment quality guidelines suggested that adverse biological effects are expected to occur rarely in the sediment.
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43. 题目: Riparian land cover and hydrology influence stream dissolved organic matter composition in an agricultural watershed
文章编号: N20021501
期刊: Science of The Total Environment
作者: Oliva Pisani, David D. Bosch, Alisa W. Coffin, Dinku M. Endale, Dan Liebert, Timothy C. Strickland
更新时间: 2020-02-15
摘要: Dissolved organic matter (DOM) represents an essential component of the carbon cycle and controls biogeochemical and ecological processes in aquatic systems. The composition and reactivity of DOM are determined by the spatial distribution of its sources and its residence time in a watershed. While the effects of agricultural land cover on DOM quality have been reported across spatial and temporal scales, the influence of riparian land cover on stream DOM composition has received little attention. Furthermore, the combined effects of riparian land cover and streamflow rates on DOM composition require investigation. To this end, a multi-year (2016–2018) DOM characterization study was conducted using bi-weekly water samples collected from seven sub-watersheds nested within the Little River Experimental Watershed (LREW) near Tifton, Georgia, USA. DOM optical properties were determined to assess compositional variations using UV–Vis and excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis. PARAFAC analysis indicated that DOM in the LREW was dominated by three humic-like fluorescing components of terrestrial, microbial, and anthropogenic origin and a protein-like component. DOM composition was influenced by riparian land cover and hydrology, and shifted towards recently produced, low molecular weight DOM with low aromaticity as the percentage of agricultural land within riparian wetlands increased. During periods of high discharge and high baseflow, the DOM pool was dominated by recalcitrant and terrestrial-derived material but shifted towards protein-like and microbial-derived with increasing cropland in the riparian area. The results of this two-year study indicate that the replacement of forested riparian buffers with agricultural land can result in altered DOM composition which may affect carbon cycling and downstream water quality in agricultural watersheds.
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44. 题目: Molecular Identification of Water-Extractable Organic Carbon from Thermally Heated Soils: C-13 NMR and Accurate Mass Analyses Find Benzene and Pyridine Carboxylic Acids
文章编号: N20021415
期刊: Environmental Science & Technology
作者: E. Michael Thurman, Yun Yu, Imma Ferrer, Kevin A. Thorn, Fernando L. Rosario-Ortiz
更新时间: 2020-02-14
摘要: To simulate the effects of wildfire on the combustion process in soils and their potential to leach organic compounds into streams and groundwater, mineral soil samples were heated at temperatures of 150–550 °C. Then, the soils were leached with deionized water, filtered, and analyzed for dissolved organic carbon. The water extract was concentrated by both XAD-8 and XAD-4 resins and analyzed by C-13 nuclear magnetic resonance and liquid chromatography time-of-flight mass spectrometry. Approximately 15–20% of the water-extractable organic carbon was identified as benzene dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acid isomers, commonly called BPCAs. Also identified were isomers of pyridine dicarboxylic acids and tricarboxylic acids (PCAs). The conversion of soil organic carbon to BPCAs occurs at 250 °C and reaches a maximum between 350 and 450 °C. At higher temperatures (>450 °C), the BPCA concentrations decrease, suggesting decarboxylation and conversion to carbon dioxide and water. This is the first report of BPCAs and PCAs in water-extractable organic carbon from thermally altered soil and suggest that these compounds are possible candidates for further water-quality studies in watersheds affected by wildfire. Finally, BPCAs and PCAs could contribute to the black carbon and nitrogen in seawater and are worthy of future investigation.

45. 题目: Application of Hydrochar Altered Soil Microbial Community Composition and the Molecular Structure of Native Soil Organic Carbon in a Paddy Soil
文章编号: N20021414
期刊: Environmental Science & Technology
作者: Ke Sun, Lanfang Han, Yan Yang, Xinghui Xia, Zhifeng Yang, Fengchang Wu, Fangbai Li, Yanfang Feng, Baoshan Xing
更新时间: 2020-02-14
摘要: The benefits and disadvantages of hydrochar incorporation into soil have been heavily researched. However, the effect of hydrochar application on the soil microbial communities and the molecular structure of native soil organic carbon (SOC) has not been thoroughly elucidated. This study conducted an incubation experiment at 25 °C for 135 days using a soil column with 0.5 and 1.5% hydrochar-amended paddy soil to explore the interconnections between changes in soil properties and microbial communities and shifts in native SOC structure using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) and NMR after hydrochar application. Hydrochar addition decreased the labile SOC fraction by 15.6–33.6% and increased the stable SOC fraction by 10.3–27.0%. These effects were significantly stronger for 1.5% hydrochar-treated soil. Additionally, hydrochar addition induced the native SOC with 1.0–3.0% more carbon and 6.0–13.0% higher molecular weight. The SOC in hydrochar-amended soil contained more aromatic compounds but fewer carbohydrates and lower polarity. This was resulted by a statistically significant reduction in Sphingobacterium, which was active in polycyclic aromatic hydrocarbon degradation, and an increase in Flavobacterium, Anaerolinea, Penicillium, and Acremonium, which were the efficient decomposers of labile SOC. These findings will help elucidate the potential influence of hydrochar on the carbon biogeochemical cycle in the soil.

46. 题目: Major role of particle fragmentation in regulating biological sequestration of CO 2 by the oceans
文章编号: N20021413
期刊: Science
作者: Nathan Briggs, Giorgio Dall’Olmo, Hervé Claustre
更新时间: 2020-02-14
摘要: A critical driver of the ocean carbon cycle is the downward flux of sinking organic particles, which acts to lower the atmospheric carbon dioxide concentration. This downward flux is reduced by more than 70% in the mesopelagic zone (100 to 1000 meters of depth), but this loss cannot be fully accounted for by current measurements. For decades, it has been hypothesized that the missing loss could be explained by the fragmentation of large aggregates into small particles, although data to test this hypothesis have been lacking. In this work, using robotic observations, we quantified total mesopelagic fragmentation during 34 high-flux events across multiple ocean regions and found that fragmentation accounted for 49 ± 22% of the observed flux loss. Therefore, fragmentation may be the primary process controlling the sequestration of sinking organic carbon.

47. 题目: Effects of straw and its biochar applications on the abundance and community structure of CO 2 -fixing bacteria in a sandy agricultural soil
文章编号: N20021412
期刊: Journal of Soils and Sediments
作者: Peipei Li, Wenju Chen, Yanlai Han, Daichang Wang, Yuting Zhang, Chuanfa Wu
更新时间: 2020-02-14
摘要: Purpose: Crop straw and biochar application can potentially increase carbon sequestration and lead to changes in the microbial community in agricultural soils. Sequestration of CO2 by autotrophic microorganisms is key to biogeochemical carbon cycling in soil ecosystems. The effects of straw and its biochar, derived from slow pyrolysis, on CO2 fixation bacteria in sandy soils, remain unclear. Therefore, this study compared the response of abundance and community of CO2 fixation bacteria to the two straw application methods in a sandy agricultural soil. The overall aim of the study was to achieve an efficient use of straw residues for the soil sustainablility. Materials and methods: We investigated the soil organic carbon content and autotrophic bacteria over four consecutive years (2014–2018) in a field experiment, including the following four treatments: whole maize straw amendment (S), whole maize straw translated biochar amendment (B), half biochar and half straw amendment (BS), and control (CK) without straw or biochar amendment. The autotrophic bacterial abundance and community structure were measured using molecular methods of real-time PCR, terminal restriction fragment length polymorphisms (T-RFLP), and a clone library targeting the large subunit gene (cbbL) of ribulose-1,5-bisphosphate carboxylase/oxygenase. Results and discussion: The results showed that the content of soil total organic carbon (TOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) in B, S, and BS treatments was significantly increased compared with the CK treatment. Soil TOC and available potassium (AK) in the B treatment significantly increased by 15.4% and 23.3%, respectively, but soil bulk density, DOC, and MBC significantly decreased by 8.5%, 10.6%, and 14.5%, respectively, compared with the S treatment. The abundance of the cbbL gene as well as of the bacterial 16S rRNA gene increased significantly in straw or biochar application treatments as compared to the CK treatment. The B treatment, but not the BS treatment, significantly increased the cbbL gene abundance when compared to the S treatment. No significant differences were observed in the bacterial 16S rRNA gene abundance among the three straw or biochar applications. The application of straw biochar could increase the diversity of the autotrophic bacteria, which also altered the overall microbial composition. Physicochemical properties of the soil, such as soil pH, SOC, and bulk density, can help explain the shift in soil microbial composition observed in the study. Conclusions: Taken together, our results suggest that straw biochar, rather than straw application, leads to an increase in the abundance and diversity of CO2-fixing bacteria, which would be advantageous for soil autotrophic CO2 fixation.

48. 题目: Seasonal irrigation affects the partitioning of new photosynthate carbon in soil
文章编号: N20021411
期刊: Soil Biology and Biochemistry
作者: Carmen R. Carmona, Timothy J. Clough, Samuel R. McNally, Michael H. Beare, Craig S. Tregurtha, John E. Hunt
更新时间: 2020-02-14
摘要: Long-term irrigation of temperate pastures has been reported to either increase or decrease soil organic carbon (SOC) stocks when compared with dryland systems. Understanding the short-term effects of irrigation on the fixation and partitioning of carbon (C) to plant and soil components may be important to explaining the observed differences. Continuous 13CO2 pulse labelling of ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) planted mesocosms was used to quantify the net accumulation and partitioning of new photosynthate C to above- and below-ground components of the plant-soil system, including soil particle size fractions: > 250 μm, 53–250 μm, 20–53 μm, 5–20 μm and <5 μm, under simulated irrigation and dryland conditions.After the 13CO2 labelling, irrigation increased the quantity of 13C partitioned into herbage by 16%, while reducing the quantity partitioned into roots in the 15–25 cm soil depth by 35%. However, less new photosynthate C was observed in rhizosphere soil (0–15 cm depth), while more new photosynthate C was partitioned into the 53–250 μm and <5 μm soil fractions under irrigation. Despite these differences, the net amount of new photosynthate C in the whole soil (0–25 cm depth) was similar between treatments (2511 kg new C ha−1 dryland and 2509 kg new C ha−1 irrigated). Therefore, Irrigation did not increase the net amount of new photosynthate C in the soil despite increased above-ground pasture productivity.Based in our results, we hypothesise that the recently reported losses of SOC from irrigated pastures may be driven by faster turnover of root-derived C, which may explain the increase in photosynthate C in the fine POM soil size fraction (53–250 μm), rather than a reduction in photosynthate C inputs to the soil.
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49. 题目: Evolution of the functionalities and structures of biochar in pyrolysis of poplar in a wide temperature range
文章编号: N20021410
期刊: Bioresource Technology
作者: Chenting Zhang, Zhanming Zhang, Lijun Zhang, Qingyin Li, Cuncheng Li, Guozhu Chen, Shu Zhang, Qing Liu, Xun Hu
更新时间: 2020-02-14
摘要: This study studied the change of functionalities in the biochar formed in pyrolysis of poplar wood in a wide range of temperature. The in situ Diffuse Reflectance Infrared Fourier transform spectroscopy characterization indicated that aldehydes and ketones functionalities formation initiated at 100°C, dominated at 300 to 500°C. Carboxyl group was less stable than carbonyls. Cellulose crystal in poplar decomposed slightly at 300°C and significantly at 350°C. The temperature from 250 to 350°C significantly affected biochar yields, while the drastic fusion of the ring structures in biochar occurred from 550 to 650°C, making biochar more aliphatic while less more aromatic. High pyrolysis temperature also created more defective structures in the biochar and favored the absorption of the CO2 generated during the pyrolysis. The results provide the reference information for understanding the structural configuration and evolution of the functionalities during in pyrolysis of poplar biomass.
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50. 题目: As(III) and As(V) Removal Mechanisms by Fe-modified Biochar Characterized Using Synchrotron-based X-ray Absorption Spectroscopy and Confocal Micro-X-ray Fluorescence Imaging
文章编号: N20021409
期刊: Bioresource Technology
作者: Yong Xu, Xianjun Xie, Yu Feng, Muhammad Aqeel Ashraf, YingYing Liu, Chunli Su, Kun Qian, Peng Liu
更新时间: 2020-02-14
摘要: Batch experiments followed by solid-phase analyses were conducted to explore As(III) and As(V) removal mechanisms by Fe-modified biochars (FeBC) pyrolyzed at different temperatures (300, 600, and 900 °C). Arsenic removal by FeBC, best described by pseudo-second order kinetic and Langmuir isotherm models, increased from 73.8 to 99.9% for As(III) and 86.8 to 99.9% for As(V) as the pyrolysis temperature increased. The addition of calcite enhanced the removal efficiency (all >99%). Confocal micro-X-ray fluorescence imaging (CMXRFI) analyses indicated As co-located with Fe and diffused deeper into the particles as the pyrolysis temperature increased. For As(III)-spiked systems, X-ray absorption near-edge structure (XANES) data indicated 20.2 to 81.5% of As(III) was oxidized to As(V) as the pyrolysis temperature increased; an increase of oxidation efficiency was observed after adding calcite. For As(V)-spiked systems, no As(V) reduction was observed. Overall, As(III/V) removal using FeBC was affected by the spatial distribution and species of As.
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51. 题目: Effects of high concentrations of sulfate on dissolved organic matter in paddy soils revealed by excitation-emission matrix analyzing
文章编号: N20021408
期刊: Chemosphere
作者: Qin Chen, Rong Jia, Lina Li, Dong Qu
更新时间: 2020-02-14
摘要: The problem of sulfate pollution is becoming increasingly serious in freshwater and wetlands. Since paddy fields are the largest constructed wetland in Earth’s surface, the increased sulfate input may have great effect on dissolved organic matter (DOM) in paddy soils. To understand these effects, a 24-day anaerobic incubation experiment was conducted with four Chinese paddy soils amended with high concentrations (0, 10, 25, 50, and 100 mmol·L−1) of Na2SO4. Dissolved organic carbon (DOC) and chlorophyll a (Chl a) concentrations were determined after incubation. Parallel factor analysis (PARAFAC) of the excitation–emission matrix (EEM) spectra was used to analyze the DOM composition. In all four soils, DOC concentrations generally increased with increasing sulfate concentration, while the Chl a concentrations decreased. The EEM spectra of DOM were resolved into four components by PARAFAC. With increasing sulfate concentration, the proportion of the ultraviolet C humic acid-like compound decreased and the tyrosine-like compound increased in two algae-rich soils (Sichuan and Tianjin). No obvious variation was observed in the humification index (HIX) or the ratio of peak β to peak α (β:α) in any soils with added sulfate. Specific ultra-violet absorbance at 254 nm (SUVA254) decreased with increasing sulfate concentration in Jilin, Tianjin, and Ningxia soils, and the fluorescence index (FI) decreased in two algae-rich soils. In conclusion, although sulfate addition increased the DOC concentration, the DOM composition depended more strongly on soil type and physicochemical properties than sulfate. Sulfate addition only affected soil DOM origin and composition by inhibiting algal growth in algae-rich paddy soils.

52. 题目: Assessing the sensitivity and repeatability of permanganate oxidizable carbon as a soil health metric: An interlab comparison across soils
文章编号: N20021407
期刊: Geoderma
作者: Jordon Wade, Gabriel Maltais-Landry, Dawn E. Lucas, Giulia Bongiorno, Timothy M. Bowles, Francisco J. Calderón, Steve W. Culman, Rachel Daughtridge, Jessica G. Ernakovich, Steven J. Fonte, Dinh Giang, Bethany L. Herman, Lindsey Guan, Julie D. Jastrow, Bryan H.H. Loh, Courtland Kelly, Meredith E. Mann, Roser Matamala, Elizabeth A. Miernicki, Brandon Peterson
更新时间: 2020-02-14
摘要: Soil organic matter is central to the soil health framework. Therefore, reliable indicators of changes in soil organic matter are essential to inform land management decisions. Permanganate oxidizable carbon (POXC), an emerging soil health indicator, has shown promise for being sensitive to soil management. However, strict standardization is required for widespread implementation in research and commercial contexts. Here, we used 36 soils—three from each of the 12 USDA soil orders—to determine the effects of sieve size and soil mass of analysis on POXC results. Using replicated measurements across 12 labs in the US and the EU (n = 7951 samples), we quantified the relative importance of 1) variation between labs, 2) variation within labs, 3) effect soil mass, and 4) effect of soil sieve size on the repeatability of POXC. We found a wide range of overall variability in POXC values across labs (0.03 to 171.8%; mean = 13.4%), and much of this variability was attributable to within-lab variation (median = 6.5%) independently of soil mass or sieve size. Greater soil mass (2.5 g) decreased absolute POXC values by a mean of 177 mg kg−1 soil and decreased analytical variability by 6.5%. For soils with organic carbon (SOC) >10%, greater soil mass (2.5 g) resulted in more frequent POXC values above the limit of detection whereas the lower soil mass (0.75 g) resulted in POXC values below the limit of detection for SOC contents <5%. A finer sieve size increased absolute values of POXC by 124 mg kg−1 while decreasing the analytical variability by 1.8%. In general, soils with greater SOC contents had lower analytical variability. These results point to potential standardizations of the POXC protocol that can decrease the variability of the metric. We recommend that the POXC protocol be standardized to use 2.5 g for soils <10% SOC. Sieve size was a relatively small contributor to analytical variability and therefore we recommend that this decision be tailored to the study purpose. Tradeoffs associated with these standardizations can be mitigated, ultimately providing guidance on how to standardize POXC for routine analysis.

53. 题目: Preparation of montmorillonite modified biochar with various temperatures and their mechanism for Zn ion removal
文章编号: N20021406
期刊: Journal of Hazardous Materials
作者: Jingpeng Song, Shuaishuai Zhang, Guixiang Li, Qing Du, Fan Yang
更新时间: 2020-02-14
摘要: Because of its layered structure, excellent adsorption, catalytic and ion exchange properties, strong passivation, and superior adsorption capacity for heavy metals, montmorillonite as biochar modifier was introduced. Montmorillonite modified biochar composites (BC-MNT) were successfully prepared by one-step hydrothermal progress and subsequent pyrolysis for the application of Zn (II) removal from aqueous solution. Herein, our research mainly explored the effect of different hydrothermal method/pyrolysis temperatures on the adsorption properties of montmorillonite-biochar composites, since that temperature can greatly change the surface functional groups and chemical composition and structure of biochar. Primarily, adopting VK analysis method analyzed raw biochar and montmorillonite modified biochar at different temperature condition. For further research, adsorption mechanism was realized by means of SEM-EDS, XRD, FTIR, and XPS, as concluded that electrostatic interaction between the negative charge of the interlayers and Zn (II) and surface complexation took up a dominant role. The kinetic and isothermal adsorption mathematical model fitting were also performed, which was more suitable for pseudo-second order and Freundlich model, suggesting that the limited speed stage was dominated by chemical forces. The optimal preparation temperature (350 °C) and maximum adsorption amount (8.163 mg·g−1) were determined by the adsorption experiment model.
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54. 题目: Paleo-environmental variation and its control on organic matter enrichment of black shales from shallow shelf to slope regions on the Upper Yangtze Platform during Cambrian Stage 3
文章编号: N20021405
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Yaowen Wu, Hui Tian, Dajian Gong, Tengfei Li, Qin Zhou
更新时间: 2020-02-14
摘要: To understand the evolution of oceanic redox conditions and organic matter (OM) accumulation in the shelf and slope regions of the Upper Yangtze Platform during Cambrian Stage 3, high-resolution geochemical data were obtained from two wells respectively representing shelf and slope environments. Based on redox proxies, widespread anoxic/euxinic waters with intermittent sulfidic water columns were formed from shallow shelf to deep water slope and basinal regions during Stage 2 and early Stage 3; then, widespread anoxic waters were reduced and oxic waters expanded during the middle Stage 3, after which fluctuating suboxic and oxic (occasionally anoxic) environments became predominant during late Stage 3. The presence of hyalophane and positive Eu anomalies suggest strong Ba-rich hydrothermal activities in the shelf and deep basin regions during early and middle Stage 3. The Ba-rich hydrothermal fluids and upwelling events enhanced the primary productivity in surface waters and subsequently promoted organic matter enrichment. During Stage 2 and early Stage 3, the high primary productivity driven by coastal upwelling and hydrothermal activity were the main factors controlling OM enrichment; during middle Stage 3, the local anoxic water condition became responsible for OM enrichment when oxic waters began to gradually expand; during late Stage 3, both primary productivity and redox conditions became the main control factors for OM enrichment. According to the analysis of primary productivity, redox conditions, hydrothermal activity and upwelling events, an evolution model is proposed to account for the paleo-environmental variation and the OM enrichment from shallow shelf to slope regions during Cambrian Stage 3.

55. 题目: Goethite-modified biochar ameliorates the growth of rice (Oryza sativa L.) plants by suppressing Cd and As-induced oxidative stress in Cd and As co-contaminated paddy soil
文章编号: N20021404
期刊: Science of The Total Environment
作者: Muhammad Kashif Irshad, Ali Noman, Haifa A.S. Alhaithloul, Muhammad Adeel, Yukui Rui, Tufail Shah, Sihang Zhu, Jianying Shang
更新时间: 2020-02-14
摘要: Co-contamination of soils with cadmium (Cd) and arsenic (As) in rice growing areas is a serious threat to environment and human health. Increase in soil Cd and As levels curtail the growth and development of rice plants by causing oxidative stress and reduction in photosynthetic activity. Therefore, it is necessary to formulate and evaluate different strategies for minimizing the Cd and As uptake in rice plant. We modified biochar (BC) with goethite and assessed the effects of goethite-modified biochar (GB) application on mitigating Cd and As stress in rice plant. Although BC supply to rice plants enhanced their performance in contaminated soil but application of different GB levels i.e.1.5% GB to the soil resulted in prominent improvements in physiological and biochemical attributes of rice plants grown in Cd and As co-contaminated paddy soil. It was observed that soil amendment with GB increased the plant growth, biomass, photosynthetic pigments, gas exchange attribute of rice plant and suppressed the oxidative stress in rice leaves and roots by increased antioxidant enzymes activities. Supplementing the soil with 1.5% GB incremented the iron plaque (Fe-plaque) formation and enhanced the Cd and As sequestration by Fe-plaque. Application of GB (1.5%) significantly improved the Fe content of Fe-plaque by 68.7%. Maximum Cd (1.57 mg kg−1) and As (0.85 mg kg−1) sequestration by Fe-plaque was observed with 1.5% GB treatment. Compared to the control, 1.5% GB treatment application prominently reduced the Cd content in the rice roots and shoots by 42.9%, and 56.7%, respectively and As content in the rice roots and shoots declined by 32.2%, 46.6%, respectively, compared to the control. These findings demonstrate that amending the soil with 1.5% GB can be a potential remediation strategy for checking Cd and As accumulation, reducing oxidative stress and increasing the growth of rice plant.
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56. 题目: Effects of biochar on soil microbial community and functional genes of a landfill cover three years after ecological restoration
文章编号: N20021403
期刊: Science of The Total Environment
作者: Hang Lu, Mengxue Yan, Ming Hung Wong, Wing Yin Mo, Yinghui Wang, Xun Wen Chen, Jun-Jian Wang
更新时间: 2020-02-14
摘要: Landfills, as the most common approach to disposing of municipal solid waste worldwide, disturb native ecosystems and create a need for ecological restoration. The restoration of landfill cover with biochar has shown immediate potential to improve soil microbial functions within one year. However, such characteristics could change after a longer period of time. Here, soil properties, microbial communities, and microbial functional genes related to nutrient cycling were investigated three years after the biochar amendment of the topsoil of a subtropical landfill cover. The results showed that the levels of soil organic matter, water content, total carbon (C), total nitrogen (N) and total phosphorus (P) of biochar-amended soils were higher than those of control soil. Different soil microbial community structures were observed in the biochar-amended and control soils. Nine phyla, including Proteobacteria and Acidobacteria, but not Actinobacteria or Chloroflexi, were enriched in the biochar-amended soil. Although the impact of biochar on shaping microbial communities increased after a longer period of restoration, no differences were observed in soils that were amended using different biochar:soil ratios. The abundances of functional genes related to C and N cycling decreased, whereas those of genes related to P cycling were higher in soils that received biochar amendment. This finding suggests that compared with the control soil, biochar-amended soils were less active in processes involved in C and N cycling but enhanced in processes related to P cycling. This study can serve as a reference for future ecological restoration of degraded lands using biochar.
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57. 题目: Application of organic carbon affects mineral nitrogen uptake by winter wheat and leaching in subsoil: Proximal sensing as a tool for agronomic practice
文章编号: N20021402
期刊: Science of The Total Environment
作者: Petr Holub, Karel Klem, Ivan Tůma, Jana Vavříková, Kateřina Surá, Barbora Veselá, Otmar Urban, Jaroslav Záhora
更新时间: 2020-02-14
摘要: We tested the hypothesis that application of stable forms of organic carbon (C) into the soil reduces leaching of nitrogen (N). We also examined the potential to estimate N leaching employing N-sensitive spectral reflectance indices. During three growing seasons 2013–2015, field experiment at two experimental sites combining application of distinct N doses (0 (N0), 35 (N35), 70 (N70), and 140 (N140) kg N ha−1) and two stable forms of organic C (lignohumate and compost) was established to measure N uptake by winter wheat and its leaching to subsoil layers. The spectral reflectance at canopy level was measured simultaneously with N content in leaf dry matter at the beginning of the grain filling phase. At full maturity, the above-ground biomass, grain yield, and grain protein content were evaluated. That data was used to calculate N uptake in grain. The N140 dose led to increased N uptake by grain of 64% and 73% in the wetter years 2013 and 2014, respectively, and even by 118% in the drier year 2015 in comparison with the N0 treatment. N leaching to subsoil increased substantially with higher N dose, but only in wetter years 2013 (by 74%) and 2014 (by 87%). By contrast, no effect of N dose on leached N was found in the dry year 2015. The application of organic C along with the N140 dose substantially reduced N leaching by 26% and 29% in 2014 and 2015, respectively. Moreover, we demonstrated that normalized red-edge spectral reflectance index (NRERI) is able to predict N uptake by wheat and it can serve as an indicator of N leaching in heavy-rainfall years. Our results thus point towards possible agronomic practices and use of remote-sensing techniques to reduce groundwater contamination by N-based fertilizers.
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58. 题目: In situ nitrogen functionalization of biochar via one-pot synthesis for catalytic peroxymonosulfate activation: Characteristics and performance studies
文章编号: N20021401
期刊: Separation and Purification Technology
作者: Zaeni Julia Raudlatul Jannah, Jun-Wei Lim, Zhaohui Wang, Dahu Ding, Yong-Shen Chua, Si-Ling Ng, Wen-Da Oh
更新时间: 2020-02-14
摘要: A facile and scalable one-pot synthesis method was designed to fabricate N-doped biochar from wood residue for peroxymonosulfate (PMS) activation. The urea:wood residue w/w ratio was varied from 0:1 to 100:1, and the intrinsic (surface chemistry) and extrinsic (morphology, specific surface area, etc.) properties of the N-doped biochar were systematically investigated. Notably, the urea:wood residue w/w ratio played a significant role in tuning the N species composition in the N-doped biochar. A higher urea:wood residue w/w ratio resulted in greater at.% of graphitic N and higher specific surface area. The results show that the catalyst prepared with urea:wood residue w/w ratio of 100:1 (NC800-20) manifested the greatest catalytic activity as PMS activator for organics removal due to its highly favorable combination of intrinsic (highest at.% graphitic N) and extrinsic (excellent specific surface area) properties. The catalyst loading, PMS dosage and pH were found to be operationally crucial for PMS activation. Under the best condition, the NC800-20 can be used to degrade various organic pollutants. The recyclability of NC800-20 was studied and while the catalytic activity gradually deteriorated over successive cycles, it can be completely restored by simple calcination at 500°C. The used catalyst was extensively characterized, revealing insights into the mechanism of PMS activation. The prevailing mechanism for PMS activation was the nonradical pathway. Overall, this research provides insights into preparing N-doped biochar with favorable extrinsic and intrinsic properties from biowaste for sustainable pollutant removal via PMS activation.
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59. 题目: Impact of Natural Organic Matter on Plutonium Vadose Zone Migration from an NH 4 Pu(V)O 2 CO 3 (s) Source
文章编号: N20021306
期刊: Environmental Science & Technology
作者: Melody Maloubier, Hilary Emerson, Kathryn Peruski, Annie B. Kersting, Mavrik Zavarin, Philip M. Almond, Daniel I Kaplan, Brian A. Powell
更新时间: 2020-02-13
摘要: We investigated the influence of natural organic matter (NOM) on the behavior of Pu(V) in the vadose zone through a combination of the field lysimeter and laboratory studies. Well-defined solid sources of NH4Pu(V)O2CO3(s) were placed in two 5-L lysimeters containing NOM-amended soil collected from the Savannah River Site (SRS) or unamended vadose zone soil and exposed to 3 years of natural South Carolina, USA, meteorological conditions. Lysimeter soil cores were removed from the field, used in desorption experiments, and characterized using wet chemistry methods and X-ray absorption spectroscopy. For both lysimeters, Pu migrated slowly with the majority (>95%) remaining within 2 cm of the source. However, without the NOM amendment, Pu was transported significantly farther than in the presence of NOM. Downward Pu migration appears to be influenced by the initial source oxidation state and composition. These Pu(V) sources exhibited significantly greater migration than previous studies using Pu(IV) or Pu(III) sources. However, batch laboratory experiments demonstrated that Pu(V) is reduced by the lysimeter soil in the order of hours, indicating that downward migration of Pu may be due to cycling between Pu(V) and Pu(IV). Under the conditions of these experiments, NOM appeared to both enhance reduction of the Pu(V) source as well as Pu sorption to soils. This indicates that NOM will tend to have a stabilizing effect on Pu migration under SRS vadose zone field conditions.

60. 题目: The role of soil organic matters and minerals on hydrogen peroxide decomposition in the soil
文章编号: N20021305
期刊: Chemosphere
作者: Hamed Vafaei Molamahmood, Jiaolong Qin, Yitong Zhu, Menglin Deng, Mingce Long
更新时间: 2020-02-13
摘要: Application of H2O2 in in-situ chemical oxidation (ISCO) for soil remediation has been limited by its rapid decomposition. However, effect of main factors involving in this phenomenon are not well understood. In this contribution, H2O2 decomposition in the six types of natural soils was investigated by kinetic analyses and soil characterizations. The grassland soil (GS) and red soil (RS) have the highest H2O2 decomposition rates (respective 0.048 and 0.069 min−1), while the paddy soil (PS) shows the lowest one (0.004 min−1). The decomposition mainly takes place on the surface adsorption sites of soil particles. PS has the highest content of SOM, which can block the active adsorption sites for H2O2 decomposition. The effects of dissolved organic matter (DOM) and biological debris in the soil are minor. Iron and manganese containing minerals are significantly influential on H2O2 decomposition, and the soil with a higher content of clay can induce faster H2O2 decomposition. The immobilized goethite (GM) and birnessite (BM) on montmorillonite were synthesized to simulate soil minerals. Results show H2O2 decomposition rates in BM is even faster than GM when the former dosage is two orders of magnitude lower than that of the latter. This indicates the crucial role of manganese minerals although their contents are generally much lower than that of iron in the soils. This study advanced the understanding of H2O2 decomposition in the soil and bring insights for H2O2 based ISCO technology in soil remediation.

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