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25841. 题目: Impact of pine leaf biochar amendment on bacterial dynamics and correlation of environmental factors during pig manure composting
文章编号: N19090105
期刊: Bioresource Technology
作者: Jiao Li, Wenjing Xing, Huanyu Bao, Jinfeng Wang, Xiaogang Tong, He Zhang, Wanqing Luo, Fuyong Wu
更新时间: 2019-09-01
摘要: The influence of pine leaf biochar (PLB) amendment on bacterial community succession and its correlation with physic-chemical parameters during pig manure (PM) composting was evaluated. The five different dosages of PLB [at 0% (T1), 2.5% (T2), 5% (T3), 10% (T4) and 15% (T5)] mixed with initial composting mass were conducted to composting for 50 days. The present study indicated that bacterial diversity was significantly (p < 0.05) higher in PLB amended treatments than the control, but T4 treatment showed the highest among the all PLB applied treatment. Firmicutes, Actinobacteria, Proteobacteria and Bacteroidete were four most abundant phyla of all the treatments. Furthermore, redundancy analysis showed that the bacterial community were significantly (p < 0.05) positively correlated with temperature, pH, TOC, CO₂ and NH₃ emissions, while they were negatively correlated with the N₂O and CH₄ emission. Overall, the results suggested that the addition of 10% PLB (T4 treatment) was a potential option to enhance the composting efficiency with significantly greater abundance of bacterial community and finally improved the compost quality.
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25842. 题目: Characterization and influence of floc under different coagulation systems on ultrafiltration membrane fouling
文章编号: N19090104
期刊: Chemosphere
作者: Xue Shen, Baoyu Gao, Kangying Guo, Qinyan Yue
更新时间: 2019-09-01
摘要: A hybrid system was developed in this study consisting of different coagulation systems and ultrafiltration (UF). Property and effect of flocs formed in different coagulation systems on ultrafiltration membrane fouling control were investigated. All three coagulation systems, as pretreatment of UF, were effective in improving membrane flux and reducing membrane resistance within an appropriate range of natural organic matters (NOM) concentration. At high initial NOM concentration, the performance of polyaluminum chloride (PAC) on NOM removal and fouling control was severely limited. For PAC-poly dimethyl diallyl ammonium chloride (PAC-PolyDMDAAC) coagulation system, the limitation of initial NOM concentration on removing NOM and alleviating membrane fouling was slightly weakened, indicating composite flocculant PAC-PolyDMDAAC produced larger flocs through combined action of charge neutralization and adsorption bridging. In PAC + PolyDMDAAC dual coagulation system, the combined action of adsorption-bridging effect, sweeping effect, and charge neutralization were the mechanisms under both low and high initial NOM concentration. Although the flocs formed in PAC + PolyDMDAAC dual coagulation system had poor recovery ability compared with those formed in PAC and PAC-PolyDMDAAC coagulation system, flocs formed through adsorption-bridging and sweeping had large size and higher ability to resist shear force, resulting in the formation of cake layer with porous and fluffy structure and less blockage in membrane pore in PAC + PolyDMDAAC dual coagulation system. These results demonstrated that dual coagulation system combined PAC coagulation and PolyDMDAAC flocculation as a pretreatment of UF process can improve the characteristics of flocs and structure of cake layer for improving NOM removal and controlling membrane fouling.
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25843. 题目: Reconstructing organic matter sources and rain rates in the southern West Pacific Warm Pool during the transition from the deglaciation period to early Holocene
文章编号: N19090103
期刊: Chemical Geology
作者: Linying Chen, Min Luo, Andrew W. Dale, Harunur Rashid, Gang Lin, Duofu Chen
更新时间: 2019-09-01
摘要: Transient features in the organic carbon content of deep-sea sediment cores resulting from changes in the flux and/or quality of organic matter input are not uncommon. We examined the geochemical characteristics of sediments retrieved with a gravity core from the northwestern Solomon Sea (3908 m water depth), southern West Pacific Warm Pool (WPWP). δ¹³C and δ¹⁵N of sedimentary organic matter, together with TOC/TN data suggest that the organic material is characterized by a mixture of marine and terrestrial origins with a higher contribution from marine algae. The data were analyzed with an inverse non-steady-state reaction-transport model to examine the magnitude and variability of particulate organic carbon (POC) flux to the seafloor during the transition between the deglaciation period and early Holocene. Measured POC content and porewater NO₃⁻, NH₄⁺, DIC and SO₄²⁻ concentrations were used to constrain the model. Hindcast results revealed that POC flux decreased from 75 to 37.5 μg cm⁻² yr⁻¹ during the deglaciation–early Holocene transition. The rate of POC degradation in the present setting is slightly lower compared to that in the pre-Holocene setting. The synchronous decline in the relative contribution of terrestrial organic matter input and rapid sea level rise during this transition suggest that sea level, rather than surface productivity, is the dominant factor controlling the POC deposition flux in the Solomon Sea. This is conceivable because the sampling site is proximal to high-relief islands with high rainfall, a well-developed submarine canyon system and narrow and steep continental margins. Consequently, we suggest that deep-water basins in proximity to similar high-relief mountainous islands in the tropical Pacific may represent important sinks for terrestrial organic material, especially during sea level lowstands.

25844. 题目: Removal of phosphate from aqueous solution using MgO-modified magnetic biochar derived from anaerobic digestion residue
文章编号: N19090102
期刊: Journal of Environmental Management
作者: Jiwei Liu, Jianguo Jiang, Aikelaimu Aihemaiti, Yuan Meng, Meng Yang, Yiwen Xu, Yuchen Gao, Quan Zou, Xuejing Chen
更新时间: 2019-09-01
摘要: A novel MgO-modified magnetic biochar (MgO@MBC) was made by chemical co-precipitation of Mg²⁺/Fe³⁺ on anaerobic digestion residue (ADR) and subsequently pyrolyzing at different temperatures. MgO@MBC was used for phosphate recovery from aqueous solution. The physicochemical properties of MgO@MBC were comprehensively investigated using TEM-EDS, FT-IR, XRD, VSM, N₂ adsorption-desorption and TGA. Results showed that MgO/γ-Fe₂O₃ nanoparticles were successfully deposited onto the surface of BC. The effects of reaction temperature, initial solution pH, MgO@MBC dosage, coexisting anions and phosphate concentration on the removal of phosphate by MgO@MBC were researched. Additionally, the adsorption process of phosphate onto MgO@MBC was well described by the pseudo second-order and pseudo first-order models, which indicated a chemisorption and physisorption process. Besides, the maximum adsorption capacity of MgO@MBC for phosphate by the Langmuir model were 149.25 mg/g at 25 °C. Moreover, the thermodynamic study suggested that the adsorption of phosphate onto MgO@MBC was a spontaneous and endothermic process. The adsorption mechanisms including physical absorption, surface electrostatic attraction, surface complexation and precipitation were revealed. It could be concluded that MgO@MBC exhibited high removal efficiency of phosphate and excellent magnetic property for the recovery. MgO@MBC could be utilized as a magnetically recoverable adsorbent to realize phosphate recovery and MgO@MBC after the adsorpion of phosphate could be applied in agricultural production as a fertilizer.
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25845. 题目: Assessment of combustion and emission behavior of corn straw biochar briquette fuels under different temperatures
文章编号: N19090101
期刊: Journal of Environmental Management
作者: Ting Wang, Yuening Li, Dengke Zhi, Yingchao Lin, Kai He, Boyang Liu, Hongjun Mao
更新时间: 2019-09-01
摘要: The 350 °C and 700 °C corn straw biochars were used to produce solid fuel briquettes. NovoGro (NG), an industrial by-product, were selected as a binder in the briquetting process. The ratios of the raw material to NG was assumed as 100:1 and 50:1 (denoted as 350NB₁, 350NB₂, 700NB₁ and 700NB₂, respectively). The physicochemical and morphological properties, combustion characteristics and gas emissions of the four briquettes were investigated. The results revealed that the biochars and the NG binder performed a good combination. The low temperature biochar briquettes, especially 350NB₂, had excellent combustion characteristics, including low H/C and O/C ratios (0.17 and 0.82), low gas emissions (104.06 mg/m³ of CO, 157.25 mg/m³ of NO_x and 18.92 mg/m³ of SO₂), optimal resistance to mechanical shock (~90%) and high calorific values (21.48 MJ/kg). Thus, NG is a good binder for the briquetting of biochar. The low temperature biochar was a good feedstock for solid fuel production in the improvement of the combustion and emission quality.
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25846. 题目: Dissolved organic nutrients dominate melting surface ice of the Dark Zone (Greenland Ice Sheet)
文章编号: N19083111
期刊: Biogeosciences
作者: Alexandra T. Holland, Christopher J. Williamson, Fotis Sgouridis, Andrew J. Tedstone, Jenine McCutcheon, Joseph M. Cook, Ewa Poniecka, Marian L. Yallop, Martyn Tranter, Alexandre M. Anesio
更新时间: 2019-08-31
摘要: Glaciers and ice sheets host abundant and dynamic communities of microorganisms on the ice surface (supraglacial environments). Recently, it has been shown that Streptophyte glacier algae blooming on the surface ice of the south-western coast of the Greenland Ice Sheet are a significant contributor to the 15-year marked decrease in albedo. Currently, little is known about the constraints, such as nutrient availability, on this large-scale algal bloom. In this study, we investigate the relative abundances of dissolved inorganic and dissolved organic macronutrients (N and P) in these darkening surface ice environments. Three distinct ice surfaces, with low, medium and high visible impurity loadings, supraglacial stream water and cryoconite hole water, were sampled. Our results show a clear dominance of the organic phase in all ice surface samples containing low, medium and high visible impurity loadings, with 93 % of the total dissolved nitrogen and 67 % of the total dissolved phosphorus in the organic phase. Mean concentrations in low, medium and high visible impurity surface ice environments are 0.91, 0.62 and 1.0 µM for dissolved inorganic nitrogen (DIN), 5.1, 11 and 14 µM for dissolved organic nitrogen (DON), 0.03, 0.07 and 0.05 µM for dissolved inorganic phosphorus (DIP) and 0.10, 0.15 and 0.12 µM for dissolved organic phosphorus (DOP), respectively. DON concentrations in all three surface ice samples are significantly higher than DON concentrations in supraglacial streams and cryoconite hole water (0 and 0.7 µM, respectively). DOP concentrations are higher in all three surface ice samples compared to supraglacial streams and cryoconite hole water (0.07 µM for both). Dissolved organic carbon (DOC) concentrations increase with the amount of visible impurities present (low: 83 µM, medium: 173 µM and high: 242 µM) and are elevated compared to supraglacial streams and cryoconite hole water (30 and 50 µM, respectively). We speculate that the architecture of the weathering crust, which impacts on water flow paths and storage in the melting surface ice and/or the production of extracellular polymeric substances (EPS), containing both N and P in conjunction with C, is responsible for the temporary retention of DON and DOP in the melting surface ice. The unusual presence of measurable DIP and DIN, principally as NH4+, in the melting surface ice environments suggests that factors other than macronutrient limitation are controlling the extent and magnitude of the glacier algae.

25847. 题目: Enhanced Photodegradation of Extracellular Antibiotic Resistance Genes by Dissolved Organic Matter Photosensitization
文章编号: N19083110
期刊: Environmental Science & Technology
作者: Xin Zhang, Jing Li, Wen-Yuan Fan, Mu-Cen Yao, Li Yuan, Guo-Ping Sheng
更新时间: 2019-08-31
摘要: Extracellular antibiotic resistance genes (eARGs) contribute to antibiotic resistance, and as such, they pose a serious threat to human health. eARGs, regarded as an emerging contaminant, have been widely detected in various bodies of water. Degradation greatly weakens their distribution potential and environmental risks. Dissolved organic matter (DOM), mainly consisted of humic substances, carbohydrates, and organic acids, is ubiquitous in diverse waters and significantly affects the degradation of coexisting contaminants. However, the photodegradation of eARGs in natural water, especially regarding the roles of DOM in this process, remains unknown. Herein, we investigated the eARGs photodegradation in waters with and without DOM. Illumination has been found to effectively photodegrade eARGs, and this process was significantly enhanced by DOM. Further experiments revealed that photosensitization of DOM produced hydroxyl radicals (•OH) to enhance plasmid strand breaks and produced singlet oxygen (1O2) to accelerate the guanine oxidation, which in turn promoted the photodegradation of plasmid-carried eARGs. Transformation assays indicated that eARGs transformation efficiencies were reduced after their photodegradation. The presence of DOM accelerated the decreases of eARGs transformation efficiencies under illumination. DOM concentration and some ions (e.g., NO3–, NO2–, HCO3–, Br–, and Fe3+) affected •OH or 1O2 levels, further influencing the photodegradation of eARGs. Overall, eARGs photodegradation in aquatic environments is a crucial process both in the reduction of eARGs concentrations and in transformation efficiencies. This work facilitated us to better understand the fate of eARGs in waters.

25848. 题目: Global-change controls on soil-carbon accumulation and loss in coastal vegetated ecosystems
文章编号: N19083109
期刊: Nature Geoscience
作者: Amanda C. Spivak, Jonathan Sanderman, Jennifer L. Bowen, Elizabeth A. Canuel, Charles S. Hopkinson
更新时间: 2019-08-31
摘要: Coastal seagrass, mangrove and salt-marsh ecosystems—also termed blue-carbon ecosystems—play an important role in the global carbon cycle. Much of the organic carbon they store rests in soils that have accumulated over thousands of years. Rapidly changing climate and environmental conditions, including sea-level rise, warming, eutrophication and landscape development, will impact decomposition and thus the global reservoir of blue soil organic carbon. Yet, it remains unclear how these disturbances will affect the key biogeochemical mechanisms controlling decomposition—mineral protection, redox zonation, water content and movement, and plant–microbe interactions. We assess the spatial and temporal scales over which decomposition mechanisms operate and how their effectiveness may change following disturbances. We suggest that better integration of decomposition mechanisms into blue-carbon models may improve predictions of soil organic carbon stores and facilitate incorporation of coastal vegetated ecosystems into global budgets and management tools.

25849. 题目: Effects of land reclamation on the physical, chemical, and microbial quantity and enzyme activity properties of degraded agricultural soils
文章编号: N19083108
期刊: Journal of Soils and Sediments
作者: Le Qi, Peng Zhou, Laishu Yang, Ming Gao
更新时间: 2019-08-31
摘要: Purpose: Land reclamation, as a measure of increasing cultivated land area, is being popularized in China in the past decades. However, the impact of land reclamation on soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometry, microbial quantity, and enzyme activities has been rarely studied. The objective of this study was to know how land reclamation affected soil properties in agricultural soils. Materials and methods: Soil samples were collected at 0–20, 20–40, and 40–60 cm depths before and after land reclamation of degraded soils in a village of southwest China. The samples were used to determine soil bulk density, porosity, moisture content, texture, pH, soil C, N, and P nutrient properties, microbial quantity, and enzyme activities in agricultural soils. Results and discussion: The soil clay content was increased by 59.7%, while the soil organic matter (SOM), available phosphorus (AP), total potassium, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and activities of catalase and urease enzymes were decreased by 49.9, 83.4, 32.8, 20.3, and 47.9%, respectively, at 0–20 cm of the soil. The decrease of SOM contributed to the decrease of MBC and MBN at 0–20 cm after the land reclamation. The soil texture had better capacity of water and fertilizer retention. Medium sand (> 0.25 mm) content, AP, the ratio of C to N, and activities of catalase were decreased, but pH and the ratio of N to P were increased at 20–40 and 40–60 cm. The clay content, medium silt (0.006–0.01 mm), total N, and quantity of fungi and actinomycetes were increased at 40–60 cm after the land reclamation. Conclusions: Soil nutrient and enzyme activities at 0–20 cm were decreased but soil total microbial biomass was not disturbed at 0–20, 20–40, and 40–60 cm depths, after the land reclamation. The decrease of soil organic matter at 0–20 cm contributed to the decrease of MBC and MBN affected by land reclamation activities. Therefore, topsoil requires better management to preserve soil nutrients and enzyme activities after land reclamation.

25850. 题目: How to measure, report and verify soil carbon change to realise the potential of soil carbon sequestration for atmospheric greenhouse gas removal
文章编号: N19083107
期刊: Global Change Biology
作者: Pete Smith, Jean‐Francois Soussana, Denis Angers, Louis Schipper, Claire Chenu, Daniel P. Rasse, Niels H. Batjes, Fenny van Egmond, Stephen McNeill, Matthias Kuhnert, Cristina Arias‐Navarro, Jorgen E. Olesen, Ngonidzashe Chirinda, Dario Fornara, Eva Wollenberg, Jorge Álvaro‐Fuentes, Alberto Sanz‐Cobena, Katja Klumpp
更新时间: 2019-08-31
摘要: There is growing international interest in better managing soils to increase soil organic carbon content to contribute to climate change mitigation, to enhance resilience to climate change and to underpin food security, through initiatives such as international “4p1000″ initiative and the FAO's Global assessment of soil organic carbon sequestration potential (GSOCseq) programme. Since soil organic carbon content of soils cannot be easily measured, a key barrier to implementing programmes to increase soil organic carbon at large scale, is the need for credible and reliable measurement/monitoring, reporting and verification (MRV) platforms, both for national reporting and for emissions trading. Without such platforms, investments could be considered risky.

25851. 题目: Comparison of methylmercury accumulation in wheat and rice grown in straw-amended paddy soil
文章编号: N19083106
期刊: Science of The Total Environment
作者: Yongjie Wang, Zongya Chen, Yonggui Wu, Huan Zhong
更新时间: 2019-08-31
摘要: Paddy soil is a key area of methylmercury (MeHg) production and is dominated by fluctuating redox conditions following rice plant growth or rice-wheat rotation planting in eastern and southern Asia. The role of organic matter in the formation of MeHg under these biogeochemical redox cycles remains poorly understood, especially in certain mercury (Hg)-contaminated paddy soils. Here, we provide a detailed understanding of the formation of MeHg and its accumulation in crops (i.e., wheat and rice) in rice-wheat rotation systems under straw return. Two series of experiments, pot and microcosm experiments, were performed using Hg-contaminated paddy soil with 1% (w/w) wheat or rice straw addition under aerobic or anoxic conditions. The results showed that straw amendments increased MeHg levels in wheat (by 225%) and rice (by 20%) grains, most likely due to the elevated soil MeHg following straw amendment. Microcosm experiments further confirmed that fresh straw-derived organic matter enhances MeHg net production in soil through an overall increase in the activity of sulfate-reducing bacteria (SRB), particularly under anoxic conditions. Our study clearly demonstrated that straw amendment enhanced MeHg accumulation in wheat and rice grains and highlighted that straw return in Hg-contaminated soils may increase the health risk of MeHg exposure to local residents via crop consumption. Thus, some guidance should be provided for crop residue return in rice-wheat rotation system farming practices.
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25852. 题目: Assessing effects of dissolved organic carbon and water hardness on metal toxicity to Ceriodaphnia dubia using diffusive gradients in thin films (DGT)
文章编号: N19083105
期刊: Science of The Total Environment
作者: Michael H. Paller, S. Michele Harmon, Anna Sophia Knox, Wendy W. Kuhne, Nancy V. Halverson
更新时间: 2019-08-31
摘要: We evaluated the ability of diffusive gradients in thin films (DGT) to assess the effects of water hardness and dissolved organic carbon (DOC consisting of humic acids) on Cu and Zn toxicity (i.e., 48 h LC50s) to Ceriodaphnia dubia. When DOC was high, Cu concentrations measured by DGT (DGT Cu) were significantly lower than Cu concentrations in water (dissolved Cu), and DGT LC50s were significantly lower than LC50s based on dissolved concentrations. When DOC was low, differences between dissolved Cu and DGT Cu were small, as were differences between dissolved LC50s and DGT LC50s. Differences between DGT and dissolved measurements of Zn were small compared with the differences observed for Cu, and DGT Zn LC50s were relatively similar to dissolved Zn LC50s. Humic acids formed strong organic-Cu complexes that were both inaccessible for biological uptake and excluded by DGT, which selected for free or weakly bound Cu. In contrast, Zn did not form strong complexes with DOC that greatly affected either toxicity or the measurement of Zn by DGT. The effects of hardness on DGT measurements of Cu and Zn were smaller and more complex than the effects of DOC. Large, statistically significant differences between DGT measurements of Cu in low and high DOC water accurately reflected the strong effects of DOC on Cu toxicity. However, the effects of DOC were inconsistent for Zn, and DGT provided less information about the toxic fraction of this metal.
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25853. 题目: Comparison of the adsorption behaviors for methylene blue on two renewable gels with different physical state
文章编号: N19083104
期刊: Environmental Pollution
作者: Jinli Qiu, Pei Fan, Yuefeng Feng, Fuqiang Liu, Chen Ling, Aimin Li
更新时间: 2019-08-31
摘要: High removal efficiency and excellent recyclability are the fundamental qualities that an outstanding adsorbent used for organic dye removal should possess. In this study, two recyclable gels (sodium alginate/Ca/fiber: SCFA hydrogels; cellulose nanofiber/chitosan: CNFCS aerogels) were successfully fabricated using the facile method. Additionally, the as-prepared adsorbents were investigated using a series of characterizations. The adsorption behavior and anti-interference performance of the synthesized gels were compared by choosing methylene blue (MB) as the model pollutant. The kinetic behavior of the gels towards MB was consistent with the pseudo first-order model, and the SCFA hydrogels reached adsorption equilibrium faster than the CNFCS aerogels. The maximum adsorption capacity of MB on the SCFA hydrogels and CNFCS aerogels was 1335.0 and 164.5 mg g⁻¹ (pH = 7.0, dosage: 0.5 g/L; initial concentration from 15 to 180 mg L⁻¹), respectively. More specifically, we found that the co-existing anions had different effects on MB adsorption over the gels used for MB removal. Furthermore, for the SCFA hydrogels, co-existing natural organic matter (NOM) at low concentrations enhanced MB adsorption, and then stabilized as the concentration of NOM increased. However, this increasing trend was not observed for MB adsorption on CNFCS aerogels; these gels exhibited a slight decrease at first, and then showed no change. Nevertheless, both the gels exhibited superior regeneration and recycling abilities.
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25854. 题目: Lipid biomarkers in lacustrine sediments of subtropical northeastern Mexico and inferred ecosystem changes during the late Pleistocene and Holocene
文章编号: N19083103
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: C.M. Chávez-Lara, J. Holtvoeth, P.D. Roy, R.D. Pancost
更新时间: 2019-08-31
摘要: Evolution of ecosystems in the northeastern Mexico since the Last Glacial Maximum (LGM) and through the Holocene are yet to be fully characterised, creating a gap in our understanding of the ecological response to climate change in this water scarce region. Here we explore the response of lacustrine and surrounding terrestrial habitats of this region to hydrological changes of the late Pleistocene and especially the Holocene. Biomarker-based proxy data from the El Potosi Basin indicates dynamic and variable input of organic matter (OM) into the basin, with sources being the surrounding vegetation, bacterial biomass and aquatic microfauna. Changes in these inputs reveal distinct stages of ecosystem development over the last 20,000 years. Overall low lipid abundances (as a proportion of TOC) from 20 to 19 cal kyr BP, mainly from aquatic/in-situ microbial biomass and degraded terrestrial OM, are attributed to relatively low runoff. Increasing lipid proportions during the deglaciation, from 19 to 15 cal kyr BP, were mostly derived from terrestrial sources like woodland vegetation, soil and wetland vegetation, and we attribute them to more rainfall and runoff. Subsequently, the wetland biomarkers disappeared, and woodland input began to dominate the OM assemblage from 15 to 11.7 cal kyr BP. During the early- and mid-Holocene, after about 11.7 cal kyr BP, putative woodland and grass inputs decreased and the dominant vegetation appeared to shift to subtropical desert shrub, which could have been due to increasing regional aridity. The onset of the dry late Holocene was characterised by gradual environmental transition and ecosystem adaption, especially from 4.2 to 2.8 cal kyr BP. The terrestrial vegetation comprised increasing proportions of C₄ grasses, documented by changes in leaf wax carbon isotopic compositions, and potentially more open-vegetation, while the in-lake bacterial production increased. With increasing desertification from 2.8 cal kyr BP, the terrestrial productivity decreased substantially, the lake became shallower/ephemeral, and the surrounding soils became more alkaline. Changes of the limnic habitat from algal towards microbial communities occurred ~300 years after the onset of terrestrial habitat changes. During the last millennium, the C₃ components of the vegetation again dominated. This implies an enhanced moisture supply, possibly from agricultural activities. Overall, this work reveals the marked sensitivity of northeastern Mexico ecosystems to the climatic shifts that occurred since the LGM, and this perhaps indicates their vulnerability to future global warming.

25855. 题目: Prediction of soil organic matter using multi-temporal satellite images in the Songnen Plain, China
文章编号: N19083102
期刊: Geoderma
作者: Xin Dou, Xiang Wang, Huanjun Liu, Xinle Zhang, Linghua Meng, Yue Pan, Ziyang Yu, Yang Cui
更新时间: 2019-08-31
摘要: Due to confounding factors such as crop residue and soil moisture, soil organic matter (SOM) is usually estimated from soil samples in a laboratory or in the field at a local scale. In this study, laboratory and field data of crop residue, soil moisture, crop management practices, and SOM content were used in concert with multi-temporal MODIS images captured during bare soil periods over three years to construct spectral indices, which were then used as input variables to build a regional-scale SOM prediction model. Results showed that: (1) multi-temporal satellite images can be used to predict SOM content at a regional scale; (2) crop residue cover and time interval between snow melt, rainfall, and ploughing determined the optimal input variables for SOM prediction; (3) compared to a SOM model based on a single image, a multi-temporal model reduced the influence of soil moisture and improved both the stability and the accuracy of SOM prediction; (4) the best models generally used the ratio of MODIS Band 6 and Band 1 (R₆₁) as an input variable, as R₆₁ showed good correlation with SOM and less correlation with moisture; and (5) comparing different models in different years showed that models performed better in years with less crop residue. The study results can be used to improve the accuracy of quantitative estimates of the soil organic carbon pool and provide assistance in digital soil mapping.

25856. 题目: Sorption and removal of crude oil spills from seawater using peat-derived biochar: An optimization study
文章编号: N19083101
期刊: Journal of Environmental Management
作者: Khawla AlAmeri, Adewale Giwa, Lina Yousef, Abdulrahman Alraeesi, Hanifa Taher
更新时间: 2019-08-31
摘要: Bio-based sorbents are preferred over chemical-based methods for the clean-up of crude oil spills in marine environments because bio-based sorbents are more environmentally friendly. This study evaluates the use of peat-derived biochar (PB) as a bio-sorbent for the sorption and removal of crude oil spills from synthetic seawater. Experiments were designed to determine the effect of four operating factors (PB/crude oil contact time, PB dosage, oil dosage, and temperature) on two performance indicators (crude oil sorption capacity of PB, S, and oil removal efficiency, R%). Regression models containing linear, quadratic, and two-way interaction terms were developed to predict S and R% from the four factors. Response surface methodology (RSM) was employed to identify the optimum conditions for the sorption and removal of crude oil from seawater. The performance indicators were predicted with a high degree of accuracy, i.e. with coefficient of determination (R²) values exceeding 90%. The optimum values of S and R% were estimated to be 32.5 g of crude oil/g of sorbent and 91.2% respectively. These optimum values were attained after 70 min of PB/crude oil contact time and at a temperature of 45 °C. The spent sorbent maintained its performance after three cycles of regeneration and reuse, suggesting that the material is reusable.

25857. 题目: Stepwise Reduction Approach Reveals Mercury Competitive Binding and Exchange Reactions within Natural Organic Matter and Mixed Organic Ligands
文章编号: N19083011
期刊: Environmental Science & Technology
作者: Xujun Liang, Xia Lu, Jiating Zhao, Liyuan Liang, Eddy Y. Zeng, Baohua Gu
更新时间: 2019-08-30
摘要: The kinetics of mercuric ion (Hg2+) binding with heterogeneous naturally dissolved organic matter (DOM) has been hypothesized to result from competitive interactions among different organic ligands and functional groups of DOM for Hg2+. However, an experimental protocol is lacking to determine Hg2+ binding with various competitive ligands and DOM, their binding strengths, and their dynamic exchange reactions. In this study, a stepwise reduction approach using ascorbic acid (AA) and stannous tin [Sn(II)] was devised to differentiate Hg(II) species in the presence of two major functional groups in DOM: the carboxylate-bound Hg(II) is reducible by both AA and Sn(II), whereas the thiolate-bound Hg(II) is reducible only by Sn(II). Using this operational approach, the relative binding strength of Hg2+ with selected organic ligands was found in the order dimercaptopropanesulfonate (DMPS) > glutathione (GSH) > penicillamine (PEN) > cysteine (CYS) > ethylenediaminetetraacetate > citrate, acetate, and glycine at the ligand-to-Hg molar ratio < 2. Dynamic, competitive ligand exchanges for Hg2+ from weak carboxylate to strong thiolate functional groups were observed among these ligands and within DOM, and the reaction depended on the relative binding strength and abundance of thiols and carboxylates, as well as reaction time. These results provide additional insights into dynamic exchange reactions of Hg2+ within multicompositional DOM in controlling the transformation and bioavailability of Hg(II) in natural aquatic environments.

25858. 题目: Behavior of humic substances in the liquid-liquid system directly measured using tritium label
文章编号: N19083010
期刊: Chemosphere
作者: Maria G. Chernysheva, Gennadii A. Badun, Natalia A. Kulikova, Irina V. Perminova
更新时间: 2019-08-30
摘要: Humic substances (HS) in the aqueous solutions can be considered as colloidal particles formed by amphiphilic units. HS form micelles-like structures at concentrations close to 5 g/L. However colloidal behavior of HS at concentrations below 100 mg/L is unknown. Using radiotracer assay we have shown that in this concentration range HS form rare adsorption layers at the liquid/liquid interface and penetrate into the organic phase with the distribution ratio close to 10⁻³. We found that pH and HS molecular weight strongly influence on the distribution ratio but do not significantly change the adsorption. Furthermore, colloidal properties of HS are strongly depending on its origin: the highest surface activity was shown for HS separated from peat and the least was observed for HS separated from soils. We anticipate our assay to be a helpful tool for detailed analysis and modeling HS and humic-like materials colloidal behavior in the environment.
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25859. 题目: Synergistic effects of anionic surfactants on adsorption of norfloxacin by magnetic biochar derived from furfural residue
文章编号: N19083009
期刊: Environmental Pollution
作者: Changjing Li, Yuan Gao, Aimin Li, Lei Zhang, Guozhao Ji, Kongyun Zhu, Xuexue Wang, Yulin Zhang
更新时间: 2019-08-30
摘要: Norfloxacin (NOR) is a persistent organic pollutant and can be effectively removed from effluent by adsorption of biochar. However, the presence of other emerging contaminants, such as surfactants, will potentially alter adsorption performance of norfloxacin by biochar and the molecular-scale mechanisms of the interaction between surfactants and biochar remain poorly understood. In this study, adsorption of norfloxacin on magnetic biochar prepared with iron-containing furfural residue (FRMB) in the presence or absence of anionic surfactants was investigated. The adsorption of NOR was significantly affected by the initial pH and anionic surfactants-sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS). In the presence of SDS and SDBS, the maximum sorption capacities of NOR were 2.33 and 1.97 times higher than that in the absence of surfactants, reached to 698.6 mg g⁻¹ and 589.9 mg g⁻¹, respectively. The optimal pH condition which was 4 indicated that electrostatic adsorption played a decisive role in the adsorption process after introduction of SDS/SDBS. The adsorption data were fitted well by the Elovich model and Freundlich model at the optimal conditions in which both SDS and SDBS were hemimicelle (0.8 mM SDS or 0.4 mM SDBS), indicating surface heterogeneity of FRMB and the adsorption mechanism was related to the assembly of surfactants on biochar. FTIR results showed that FRMB and SDS/SDBS interacted through hydrophobic action, and more complex or aggregates were formed between the NOR and biochar/SDS/SDBS. This work highlights the synergistic enhancement effects of tested surfactants on the removal of NOR by magnetic biochar from aqueous systems.
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25860. 题目: Origin and properties of soluble brown carbon in freshly emitted and aged ambient aerosols over an urban site in India
文章编号: N19083008
期刊: Environmental Pollution
作者: Chirantan Sarkar, Chandra Venkataraman, Suman Yadav, Harish C. Phuleria, Abhijit Chatterjee
更新时间: 2019-08-30
摘要: This work investigates the absorption properties of soluble brown carbon (BrC), extracted in methanol and water, from ambient aerosol (PM₁₀) samples, collected over an urban background site in Mumbai, India. The diurnal variability was investigated in samples collected in the morning (7–11 a.m.) and afternoon (12–4 p.m.) periods. Absorption properties of BrC (in the 300–600-nm wavelength range) were measured in filter extracts of water-soluble organic carbon (WSOC) and methanol-soluble organic carbon (MSOC). WSOC and MSOC accounted for on average 52% and 77%, respectively, of the measured OC, potentially indicating unextracted BrC and rendering these values the lower bound. Compared with afternoon samples, the morning samples of MSOC and WSOC had increased BrC concentrations and absorption coefficients (b_abs365; 40%–65%). The correlation between b_abs365 and EC, ns-K⁺, and NO₃⁻ in the morning samples indicated contributions from primary sources, including both biomass and vehicular sources. The decreased b_abs365 in the afternoon samples was partly explained by mixing layer dilution, accompanied by a reduction in the concentrations of primary aerosol constituents. Furthermore, in the afternoon samples, ¹HNMR spectroscopy revealed the presence of more oxidized functional groups and significantly higher OC/EC and WSOC/OC ratios, indicating the greater aging of afternoon aerosol. The MAC₃₆₅ (m²gC⁻¹) for both WSOC and MSOC extracts decreased significantly by 20%–34% in the afternoon samples compared with the morning samples, indicating degradation in the absorption properties of the particles and potentially a change in the constituent BrC chromophores.
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