论文检索

总访问量：4109757次

总访客量：170635人

所有论文

24461. 题目: Soil organic matter characteristics in drained and rewetted peatlands of northern Germany: Chemical and spectroscopic analyses
文章编号: N19072417
期刊: Geoderma
作者: Wakene Negassa, Andre Acksel, Kai-Uwe Eckhardt, Tom Regier, Peter Leinweber
更新时间: 2019-07-24
摘要: Understanding soil organic matter concentration (SOM) and chemistry in different peatlands can help design appropriate management practices for sustainable use of peatland agroecosystems. However, detailed information on characteristics of SOM concentration and chemistry is not available for most peatland agroecosystems in general and in northern Germany in particular. In this study, we investigated the SOM concentration and chemistry of drained and rewetted percolation mires, forest and coastal peatlands. We used simple chemical analysis, pyrolysis field ionization mass spectroscopy (Py-FIMS), and carbon and nitrogen X-ray absorption near-edge structure (XANES) spectroscopy. The total organic carbon (C_org), total nitrogen (N), and total sulfur (S) contents were significantly (P < 0.05) different among the peatlands. The C_org at the surface horizons ranged from 164 to 373 g kg⁻¹, and these values were lower than that of the subsurface horizons of the studied peatlands except for the drained alder carr forest and coastal peatlands. The Py-FIMS indicated that the labile SOM compound classes (carbohydrates, phenols, and lignin monomers, and amino acids, peptides, and amino-sugars) and stable SOM compounds classes (lignin dimers, heterocyclic nitrogen compounds, and nitriles) were abundant at the surface horizons. However, the stable compound classes such as lipids, alkanes, alkenes, fatty acids, n-alkyl esters, and suberin were more abundant at the subsurface horizons than the surface horizons. The carbon K-edge spectra revealed that aromatic C, carboxylic C, O-alkyl, and aliphatic C were the predominant C functional groups, whereas N K edge spectra indicated that the amide group was the predominated N functional group. The SOM concentrations and some compound classes were higher in the rewetted sites of alder carr forest peatland (more carbohydrates, suberin and fatty acids) and of percolation mires (more lignin dimers, lipids and alkylaromatics). The results indicate that the effects of rewetting peatlands on SOM concentration and chemistry depend on peatland type.

24462. 题目: Impact of long-term nitrogen deposition on the response of dune grassland ecosystems to elevated summer ozone
文章编号: N19072416
期刊: Environmental Pollution
作者: Felicity Hayes, Bethan Lloyd, Gina Mills, Laurence Jones, Anthony J. Dore, Edward Carnell, Massimo Vieno, Nancy Dise, Nathalie Fenner
更新时间: 2019-07-24
摘要: Nitrogen deposition and tropospheric ozone are important drivers of vegetation damage, but their interactive effects are poorly understood. This study assessed whether long-term nitrogen deposition altered sensitivity to ozone in a semi-natural vegetation community. Mesocosms were collected from sand dune grassland in the UK along a nitrogen gradient (5–25 kg N/ha/y, including two plots from a long-term experiment), and fumigated for 2.5 months to simulate medium and high ozone exposure. Ozone damage to leaves was quantified for 20 ozone-sensitive species. Soil solution dissolved organic carbon (DOC) and soil extracellular enzymes were measured to investigate secondary effects on soil processes.Mesocosms from sites receiving the highest N deposition showed the least ozone-related leaf damage, while those from the least N-polluted sites were the most damaged by ozone. This was due to differences in community-level sensitivity, rather than species-level impacts. The N-polluted sites contained fewer ozone-sensitive forbs and sedges, and a higher proportion of comparatively ozone-resistant grasses. This difference in the vegetation composition of mesocosms in relation to N deposition conveyed differential resilience to ozone.Mesocosms in the highest ozone treatment showed elevated soil solution DOC with increasing site N deposition. This suggests that, despite showing relatively little leaf damage, the ‘ozone resilient’ vegetation community may still sustain physiological damage through reduced capacity to assimilate photosynthate, with its subsequent loss as DOC through the roots into the soil.We conclude that for dune grassland habitats, the regions of highest risk to ozone exposure are those that have received the lowest level of long-term nitrogen deposition. This highlights the importance of considering community- and ecosystem-scale impacts of pollutants in addition to impacts on individual species. It also underscores the need for protection of ‘clean’ habitats from air pollution and other environmental stressors.
图文摘要:

24463. 题目: Microcystin-LR removal by ion exchange: Investigating multicomponent interactions in natural waters
文章编号: N19072415
期刊: Environmental Pollution
作者: Fuhar Dixit, Benoit Barbeau, Madjid Mohseni
更新时间: 2019-07-24
摘要: Microcystin-LR (MCLR) is the most commonly encountered toxic microcystin variant. MCLR is usually present along with common surface water constituents such as inorganic ions and natural organic matter (NOM) which compete with MCLR for active sites during ion exchange (IX) process. Consequently, development of a multicomponent competitive model is essential for practical IX applications. This is critically important given that the NOM characteristics (charge density and molecular weight distribution) and inorganic ions concentrations are spatially variable and can change seasonally. In the present study, a systematic study was carried out into the multicomponent interactions of IX resin with inorganic ions and NOM during the MCLR removal process. This involved evaluation of MCLR removal in a single component system (i.e., MCLR only), a dual component system (MCLR and one other contaminant such as NOM), and a multiple component system (MCLR with NOM and different inorganic ions present in natural waters). A comprehensive understanding of the dynamic adsorption behavior showed that the experimental data for single component systems agree well with a Freundlich isotherm. For multicomponent interactions, the Equivalent Background Concentration (EBC) model which is derived from the Ideal Adsorption Solution Theory (IAST) provided the best correlation with the experimental data in natural waters. The concentrations of competing NOM and inorganic ions estimated by the EBC model were <10% of their initial concentrations. Sulphates are the most competitive inorganic ions followed by nitrates and bicarbonates and the multicomponent interactions could be well predicted by using the IAST-EBC model. However, the EBC model failed in the presence of higher molecular weight Suwannee River Humic Acid (SRHA) molecules due to neglecting of the pore blocking phenomenon. In the presence of higher molecular weight SRHA molecules, the Redlich-Peterson Isotherm (RP) model exhibited a better performance than the Sheindorf–Rebuhn–Sheintuch (SRS) and the EBC models.
图文摘要:

24464. 题目: Tillage frequency affects microbial metabolic activity and short-term changes in CO 2 fluxes within 1 week in karst ecosystems
文章编号: N19072414
期刊: Journal of Soils and Sediments
作者: Dan Xiao, Yingying Ye, Shuangshuang Xiao, Wei Zhang, Xunyang He, Na Liu, Zhihong Xu, Kelin Wang
更新时间: 2019-07-24
摘要: Purpose: Tillage disturbance can significantly affect soil microbial metabolic activity and CO₂ fluxes. Nevertheless, the influence of different tillage frequencies on microbial metabolic activity and short-term temporal changes of CO₂ fluxes remains unclear. Materials and methods: We established an in situ experiment with the following treatments: no tillage (T0), semiannual tillage (T1), tillage every 4 months (T2), bimonthly tillage (T3), and monthly tillage (T4). The microbial metabolic activity (Biolog EcoPlate), short-term (hours to days) temporal changes in CO₂ fluxes within 1 week, and soil properties were measured after 1 year of treatment. Results and discussion: The highest CO₂ emissions occurred in the first 72 h after tillage treatment and were significantly higher in T3 and T4 than in T0, T1, and T2 within 1 week. Average well color development (AWCD) values reflect microbial metabolic activity and were significantly higher in the tillage treatments (T1, T2, T3, and T4) than under no tillage. There was no significant difference in the Shannon diversity index under all treatments. A higher Simpson diversity index was observed under high tillage frequency in T2, T3, and T4 compared with T0 and T1, while the highest was observed in T2. The highest utilization of carboxylic acids, amino acids, and polymers occurred in T3 and T4 soils, whereas T2 had the highest utilization of carbohydrates, amines, and miscellaneous carbon sources. AWCD values and short-term CO₂ fluxes were significantly correlated with annual changes in soil organic carbon (△SOC), annual changes in dissolved organic carbon (△DOC), microbial biomass carbon (MBC), and large macroaggregates (> 1 mm). Conclusions: These results suggest that frequent tillage disturbance increases microbial metabolic activity, which can stimulate short-term CO₂ emissions through changes in soil aggregates, SOC, DOC, and MBC.

24465. 题目: Split N and P addition decreases straw mineralization and the priming effect of a paddy soil: a 100-day incubation experiment
文章编号: N19072413
期刊: Biology and Fertility of Soils
作者: Dongdong Wang, Zhenke Zhu, Muhammad Shahbaz, Liang Chen, Shoulong Liu, Kazuyuki Inubushi, Jinshui Wu, Tida Ge
更新时间: 2019-07-24
摘要: The effect of mineral fertilization and its application pattern on microbial activity and the subsequent CO₂ and CH₄ emissions arising from soil organic matter (SOM) or added substrate remains unclear. We quantified the decomposition of ¹³C-labeled straw and the priming effect (PE) governed by the N and P fertilizer application pattern during a 100-day experiment in a flooded soil. Straw addition increased the total CO₂ and CH₄ emissions. Straw mineralization increased by 30% and decreased by 19% after full and split NP application, respectively, compared with only straw addition. However, application of NP fertilization (full or split) inhibited straw-derived CH₄ emissions compared with only straw addition. SOM decomposition was increased by straw addition, yielding a positive PE for CO₂ emission. The application of split NP fertilization along with straw addition improved microbial activity, yielding the highest positive PE for CO₂ emission. In contrast, compared with the control (no addition), split NP application decreased the positive PE for CH₄ emission. Therefore, the straw-C-derived total CO₂ equivalent emission was decreased by split NP application. These results were mainly attributable to the increased Olsen P, microbial biomass, enzyme activity, and straw-derived C microbial use efficiency of split NP application, which negatively affected the PE for CH₄ emission; this was supported by the results of standardized total effects determined from structural equation models. Overall, compared with full application, split NP fertilizer application significantly decreased the straw-C mineralization rate and PE for CH₄ emission, thereby mitigating greenhouse gas emission and SOM storage in paddy soil.

24466. 题目: Optimisation in machine learning: An application to topsoil organic stocks prediction in a dry forest ecosystem
文章编号: N19072412
期刊: Geoderma
作者: Anika Gebauer, Victor M. Brito Gómez, Mareike Ließ
更新时间: 2019-07-24
摘要: Soil organic carbon (SOC) sequestration plays a key role in reducing the atmospheric greenhouse gas concentration. However, dry forest ecosystems in Ecuador are endangered to become a source of carbon emissions because of deforestation. Often spatial information, necessary to quantify potential carbon loss to the atmosphere, is missing. This particularly applies to remote areas of limited accessibility. This study aims to regionalise the SOC stocks of a small and poorly accessible dry forest ecosystem in southwestern Ecuador by using boosted regression tree (BRT) models. Resampling in a nested repeated k-fold cross validation approach was applied to develop robust models for a dataset of 118 samples with limited predictor information. To select an optimal set of model parameters, optimisation by differential evolution (DE) was applied for parameter tuning. Predictor selection was implemented using the same optimisation algorithm. This study demonstrates how the predictive performance of BRT models can be improved by applying an optimisation approach for parameter tuning and predictor selection. Model performance was improved by approximately 40% concerning the R². Still, the results also demonstrated the difficulties of machine learning applications in small and highly heterogeneous natural areas. Very variable or even random factors were assumed to distort the relationship between predictor and response variables. We assume that the presented approach is particularly successful in the case of a real-valued multivariate space of tuning parameters. However, this requires testing in further machine learning applications and algorithms.

24467. 题目: Quantitative evaluation of n-alkanes, PAHs, and petroleum biomarker accumulation in beach-stranded tar balls and coastal surface sediments in the Bushehr Province, Persian Gulf (Iran)
文章编号: N19072411
期刊: Marine Pollution Bulletin
作者: Mehdi Dashtbozorg, Alireza Riyahi Bakhtiari, Mohammad Reza Shushizadeh, Lobat Taghavi
更新时间: 2019-07-24
摘要: Coastal areas within the Bushehr Province (BP), Persian Gulf, Iran, face great challenges due to the heavy organic contamination caused by rapid industrialization, and the presence of numerous oil fields. In addition, in 2014, a significant number of tar balls are found along the coasts of BP. A total of 96 samples (48 coastal sediments and 48 tar balls) were taken from eight sampling points at the BP coast during the summer of 2014. These samples were analyzed to identify the sources and characteristics of their organic matter using diagnostic ratios and fingerprint analysis based on the distribution of the source-specific biomarkers of n-alkanes, PAHs,¹ hopanes and steranes. Mean concentration of n-alkanes (μg g⁻¹ dw) and PAHs (ng g⁻¹ dw) varied respectively from 405 to 220,626, and 267 to 23,568 in coastal sediments, while ranged respectively from 664 to 145,285 and 390 to 46,426 in tar balls. In addition, mean concentration of hopanes and steranes (ng g⁻¹ dw) were between 18.17 and 3349 and 184.66 to 1578 in coastal sediments, whereas in tar balls were 235–1899 and 520–1504, respectively. Pri/Phy² ratio was 0.25 to 1.51 (0.65) and 0.36 to 1 (0.63) in coastal sediment and tar ball samples, respectively, and the occurrence of UCM³ in both matrices, reflecting the petrogenic OM⁴ inputs and chronic oil contamination, respectively. The C₃₀ and C₂₉ homologues followed Gammacerane were detected in both matrices, in particular those collected from intensive industrial activities, suggesting petrogenic sources of OM. The coastal sediment PAHs profiles were significantly dominated by HMW⁵-PAHs in the Bahregan Beach (BAB) (78% of total PAHs), Bandare-Genaveh (GP) (66%), and Bandare-Bushehr (BUB) (61%) stations, while the Bashi Beach (BSB) (40%), Bandare-Kangan (KP) (57%), and Bandare-Asaluyeh (AP) (51%) stations exhibited higher proportion of LMW⁶-PAHs. PCA⁷ indicated that the tar ball and coastal sediment samples deposited along the Southwest of the BP beaches are most likely originated from the Abuzar oil. Based on the intensity of the anthropogenic activities, NPMDS⁸ analysis revealed that the GP, BAB, NNP, AP, and KP sampling sites had a high concentration of detected organic pollutants. To the best of our knowledge, this is the first study that investigates oil pollution in costal sediments and tar balls in the BP, providing insights in to the fate of oil in the coastal areas of the Persian Gulf, Iran.
图文摘要:

24468. 题目: Paleohydrological changes in southeastern China from 13.1 to 2.5 ka based on a multi-proxy peat record
文章编号: N19072410
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Xinxin Wang, Xianyu Huang
更新时间: 2019-07-24
摘要: Investigating the hydrological changes in the East Asian monsoon regions of China during the Holocene could provide important insights into the mechanism and future variability of the East Asian summer monsoon (EASM) rainfall. However, existing studies have revealed large inconsistencies in the spatiotemporal pattern of the hydrological changes in East China, probably due to different climatic sensitivities of various proxies, the uncertainties of sedimentary chronologies and unevenness of proxy record distributions. Thus, multi-proxy records with precise dating are needed, especially in southeastern China which is one of the key places to determine the spatiotemporal pattern with few hydrological records available. In this study, hopanoid flux, humification degree, the concentration of total organic carbon (TOC) and the atomic ratio between total organic carbon and total nitrogen (C/N) of organic matter were applied on Shuizhuyang (SZY) peat cores retrieved from southeastern China to reconstruct the paleohydrological changes spanning from 13.1 to 2.5 ka. Results of these proxies reveal a moderately dry period during 13.1–11.6 ka, followed by an interval of increasing aridity from 11.6 to 8.6 ka. The Holocene optimum (referred here as an effective moisture maximum) occurred at 8.6–4.4 ka before the climate became drier from 4.4 to 2.5 ka. The hydrological changes in SZY during the Holocene with a mid-Holocene Holocene optimum are consistent with the regional climate records in southeastern China. Such an overall arid-wet-arid pattern in Southeast China during the Holocene closely tracked the variations in the west-to-east sea surface temperature (SST) gradient in tropical Pacific. We preliminarily concluded the ENSO state and the western Pacific subtropical high (WPSH) position associated with variations in the thermal state of the tropical Pacific were primarily responsible for the hydrological changes in Southeast China during the Holocene. Our study added new evidence to the spatiotemporal pattern of hydrological changes in eastern China during the Holocene.

24469. 题目: Urban black carbon - source apportionment, emissions and long-range transport over the Brahmaputra River Valley
文章编号: N19072409
期刊: Science of The Total Environment
作者: Neeldip Barman, Sharad Gokhale
更新时间: 2019-07-24
摘要: This research investigates whether the vehicular black carbon emissions originated in the North-Eastern city of Guwahati are transported over and in the Brahmaputra River Valley and the Himalayas. The total black carbon was apportioned between the fossil fuel and biomass burning by real-time measurements of black carbon concentrations at two distinct locations having different traffic volumes in 2016–17. The average observed BC concentrations were 20.58, 6.42, 3.50 and 5.29 μg/m³ at the low traffic location and 22.44, 17.14, 9.2 and 16.87 μg/m³ at the high traffic location in winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. Temperature, wind speed, and solar radiation were found to have significant negative correlations with BC concentrations, while relative humidity had positive correlations. It was found that vehicles contributed over 85% of the ambient black carbon at both locations. Black carbon emission from this dominant source was estimated for 2018, which showed that from vehicles it increased to 0.44–0.55 Gg in 2018 from 0.29 to 0.33 Gg in 2011, which may result in the adverse impacts on the eco-sensitive Brahmaputra River Valley and the Himalayas. The transport and deposition of black carbon under different climatic seasons was modelled using HYSPLIT. The results showed that black carbon particulates are being transported and deposited all-round the year in the Himalayas and the surrounding region. Pre-monsoon and monsoon seasons contributed to the largest amounts of deposition, and a clear relation was found between deposition and rainfall. The total BC deposited in the Brahmaputra River Valley and the Himalayas during one year was 22,142.69 kg and 1566.53 kg with average deposition rates of 0.6452 μgm⁻² day⁻¹ and 0.0182 μgm⁻² day⁻¹, respectively.
图文摘要:

24470. 题目: The effectiveness of soil amendments, biochar and lime, in mitigating cadmium bioaccumulation in Theobroma cacao L
文章编号: N19072408
期刊: Science of The Total Environment
作者: Gideon Ramtahal, Pathmanathan Umaharan, Anand Hanuman, Carisa Davis, Leon Ali
更新时间: 2019-07-24
摘要: Cocoa (Theobroma cacao L.) is an important neotropical tree crop grown for its seeds or beans used in global chocolate and confectionary industries. Following studies showing ill effects of long-term dietary exposure of cadmium (Cd) on human health, a number of countries including the European Union (EU) have developed stringent regulations to protect consumers from exposure to cadmium. Cocoa is capable of bioaccumulating Cd in the cocoa beans when grown in soils high in cadmium and hence livelihood of cocoa farmers can be at risk if methods to mitigate the bioaccumulation of Cd are not developed. In vitro, greenhouse and field experiments were established with four, three and three replications respectively to evaluate the effectiveness of soil amendments, biochar and lime, at various application rates (0, 0.5×, 1×, 1.5× and 2× of the recommended rate), on soil pH, Cd phytoavailability and Cd bioaccumulation in Theobroma cacao L. For the in vitro study, Cd-containing soil was amended with 5 levels of biochar and lime, while for the greenhouse and field study four application rates were tested. The study showed that while lower rates were effective under in vitro conditions as you progressed from in vitro to greenhouse to field conditions the application rates and application frequency had to be increased, as the effectiveness and longevity of the treatments were compromised by environmental factors. Our study implies that the two amendments were complementary in their action and can be used in the recommended rated to reduce Cd bioaccumulation. However further studies are required on the placement of amendments to improve their effectiveness and longevity particularly under field conditions.
图文摘要:

24471. 题目: Effects of chlorine disinfection on the membrane fouling potential of bacterial strains isolated from fouled reverse osmosis membranes
文章编号: N19072407
期刊: Science of The Total Environment
作者: Yun-Hong Wang, Yin-Hu Wu, Tong Yu, Xue-Hao Zhao, Xin Tong, Yuan Bai, Zheng-Yang Huo, Hong-Ying Hu
更新时间: 2019-07-24
摘要: Biofouling of reverse osmosis (RO) membranes is an inevitable issue in wastewater reclamation and limits the application of RO systems. Chlorine disinfection is widely used as a pretreatment to control biofouling. However, the extracellular polymeric substances (EPS) and cellular inclusions released during chlorine disinfection might also cause membrane fouling. Furthermore, little is known regarding the chlorine resistance of bacterial strains found on fouled RO membranes. In this study, four bacterial strains isolated from fouled RO membranes were used as testing subjects to investigate the bacterial inactivation performance of chlorine disinfection. The effects of chlorine disinfection on the RO membrane fouling potential of these strains were also revealed. The chlorine resistance ability of Sphingopyxis sp. BM1-1 was strongest among the four strains as it secretes the highest amount of EPS per cell. The log inactivation efficiency of this strain was 1-log by 0.2 mg-Cl₂/L in 30 min, which was one to three orders of magnitude lower than that of the other strains. Although chlorine disinfection inactivated most bacterial cells (>90%), the reaction with chlorine significantly increased the RO membrane fouling potential of all bacterial solutions. To elucidate the main mechanism behind the increase in the fouling potential, we further investigated the changes in the properties of EPS, and the release of EPS and cellular inclusions during chlorine disinfection. Chlorine disinfection did not significantly affect the RO membrane fouling potential of the EPS secreted by these bacterial strains. However, dissolved organic carbon (DOC), protein, polysaccharide, and DNA concentration of all bacterial solutions increased by one to nine times after chlorine disinfection. These results indicate that large amounts of EPS and cellular inclusions were released into the solutions after the reaction with chlorine, which was the main cause of the increase in RO membrane fouling potential of the bacterial solution after chlorine disinfection.
图文摘要:

24472. 题目: Molecular changes of soil organic matter induced by root exudates in a rice paddy under CO₂ enrichment and warming of canopy air
文章编号: N19072406
期刊: Soil Biology and Biochemistry
作者: Li Xiong, Xiaoyu Liu, Giovanni Vinci, Riccardo Spaccini, Marios Drosos, Lianqing Li, Alessandro Piccolo, Genxing Pan
更新时间: 2019-07-24
摘要: While crop productivity and carbon flux/partitioning in agroecosystem have been widely addressed, potential changes in organic matter composition through root deposition are still unknown under climate change. In this study, root exudates of rice and rhizospheric topsoil were collected in a paddy field under 6 years of simulated climate changes respective of CO₂ enrichment, canopy air warming, and their combination as compared to the control. The molecular composition of root exudates was analyzed with liquid chromatography/mass spectrometry (LC/MS) while soil organic matter (SOM) was analyzed with pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), along with a phospholipid fatty acid analysis (PLFA) for characterizing soil microbial community. Compared to control, root exudation under elevated CO₂ was enhanced but the exudate composition remained unchanged. On the other hand, root exudation rate under warming was unaffected, but the exudate composition was changed. Relative abundance of phenolic compounds in root exudates under warming, was decreased by 26% but that of amino acids was increased by 53%. However, neither root exudation nor the exudate composition was altered under combined CO₂ and temperature elevation. Furthermore, increases in abundance of heterocyclic nitrogen compounds, phenolic acids and phenols (by 37%, 65%, and 26%, respectively) in SOM were relevant to the increase in bacterial/fungal (B/F) ratio under elevated CO₂. This accumulation was possibly attributed to preferential utilization of the increased root exudates by bacteria. However, the overall reduction of some highly hydrophobic SOM compounds (fatty acids, phenols, and phenolic acids) by 14%, could be induced by accelerated decomposition in line with significant decrease in B/F ratio under warming. Indeed, the decreased relative abundance of phenolic compounds such as p-coumaric acid (by 49%) in root exudates lead to fungal increase, which accelerated SOM decomposition. Yet, the molecular composition of SOM was hardly changed under the combination of elevated CO₂ and temperature. Overall, our findings suggested that in a rice paddy CO₂ enrichment increased root exudation and B/F ratio, while air warming altered the root exudate composition and decreased B/F ratio, resulting in changes of SOM composition. These results indicate that root exudates are a key component for the regulation of SOM dynamics under climate change scenarios.
图文摘要:

24473. 题目: Characterization of aquatic organic matter: Assessment, perspectives and priorities of research
文章编号: N19072405
期刊: Water Research
作者: Morgane Derrien, Simona Retelletti Brogi, Rafael Gonçalves-Araujo
更新时间: 2019-07-24
摘要: Organic matter (OM) refers to the largest reactive reservoir of carbon-based compounds on Earth. Aside of its role as a source of carbon, OM is also actively involved in a wide range of ecological functions. It also plays an important role in the solubility, toxicity, bioavailability, mobility and distribution of pollutants. Therefore, OM is a key component in the local and global carbon cycle. About 12,000 articles containing organic matter in the title were published during the past decade, with a continuous increasing number each year (ISI Web of Science). Although this topic was widely explored and its interest has significantly increased, some limitations remain. These limitations can be technical (e.g., pre-treatment processes, low-resolution instrument, data handling) and can be related to the current approach. In this review, we first present the current strategies and tools to characterize the organic matter in the aquatic environment, then we tackle several aspects of current characterization limitations. Finally, we suggest new perspectives and priorities of research to improve the current limitations. From our point of view, simultaneous studies of particulate and dissolved OM fractions should be prioritized and multi-disciplinary approach, creation of databases, controlled experiments and collaborative works should be the next targets for future OM research priorities.
图文摘要:

24474. 题目: The distribution of Pb(II)/Cd(II) adsorption mechanisms on biochars from aqueous solution: Considering the increased oxygen functional groups by HCl treatment
文章编号: N19072404
期刊: Bioresource Technology
作者: Jiawen Wu, Tao Wang, Yongsheng Zhang, Wei-Ping Pan
更新时间: 2019-07-24
摘要: The adsorption mechanisms of Pb(II) and Cd(II) in aqueous solution using camellia seed husk biochars pyrolyzed at different temperatures were studied. The adsorption of Pb(II) and Cd(II) on biochars are mainly controlled by ion exchange, oxygen functional groups (OFGs) complexation, Pb(II)/Cd(II)–π interactions, and precipitation with minerals. Compared to the raw biochars, both carboxyl and phenolic hydroxyl groups increased in the biochars washed with HCl. However, the previous research ignored the effect of the increased OFGs. Thus, a revised method was proposed from this study to more accurately calculate the contribution of four different mechanisms. Precipitation with minerals was the dominant mechanism for Pb(II) and Cd(II) removal, accounting for 80.61–89.03% and 53.57–75.84%, respectively, of the total adsorption as the pyrolysis temperature increased from 300°C to 700°C. As for oxygen functional groups complexation, the percentage of Pb(II) and Cd(II) removal were 4.76-8.55% and 11.34-29.59%, respectively.
图文摘要:

24475. 题目: Comparative production of biochars from corn stalk and cow manure
文章编号: N19072403
期刊: Bioresource Technology
作者: Ziyun Liu, Yuanhui Zhang, Zhidan Liu
更新时间: 2019-07-24
摘要: The aim of the present work was to compare corn stalk (CS) and cow manure (CM) for hydrochar production at different reaction temperatures (180–260°C) and retention times (1–4 h). CM and CS resulted in hydrochars with significantly different physicochemical properties; however, both led to similar yields (30–65%). CM-derived hydrochar had a lower carbon content but a higher nitrogen and ash content than CS-derived hydrochar. CM-derived hydrochar demonstrated potential as a soil amendment due to its higher content of nitrogen, the presence of surface functional groups and higher specific surface area in comparison to CS-derived hydrochar. In comparison, CS-derived hydrochar demonstrated suitability as a solid fuel due to its high heating value and low ignition temperature. This study revealed that the composition of lignocellulose significantly impacted the properties and thus potential applications of hydrochar.
图文摘要:

24476. 题目: Enhanced anaerobic degradation of quinoline, pyriding, and indole with polyurethane (PU), Fe₃O₄@PU, powdered activated carbon (PAC), Fe(OH)₃@PAC, biochar, and Fe(OH)₃@biochar and analysis of microbial succession in different reactors
文章编号: N19072402
期刊: Bioresource Technology
作者: Kun Li, Jingxin Shi, Yuxing Han, Chunyan Xu, Hongjun Han
更新时间: 2019-07-24
摘要: The study was to explore the feasibility of polyurethane (PU), Fe₃O₄@PU, powdered activated carbon (PAC), Fe(OH)₃@PAC, biochar, and Fe(OH)₃@biochar as biological carriers in strengthening anaerobic degradation of quinoline, pyridine, and indole. When the concentrations of pollutants were 25 mg/L and 50 mg/L, reactors based on PAC and Fe(OH)₃@PAC had higher degradation ratios than the other reactors. However, when the concentrations of pollutants were 75 mg/L and 100 mg/L, with the addition of PU and Fe₃O₄@PU, reactors began to show their superiority in the degradation of the selected NHCs. Among these, the reactor based on Fe₃O₄@PU had the optimal degradation ratio on quinoline, pyridine, and indole. PU, PAC, Fe(OH)₃@PAC, biochar, and Fe(OH)₃@biochar benefited the enrichment of Acinetobacter, Comamonas, Levilinea, Longilinea, and Desulfomicrobium. The reactor with the carrier of Fe₃O₄@PU had some specificity, which benefited the enrichment of Zoogloea, Thiobacillus, Anaeromyxobacter, Sphingobium, Terrimonas, Parcubacteria genera incertae sedis, Bdellovibrio, Rhizobium, and Acidovorax.

24477. 题目: Sorption process of municipal solid waste biochar-montmorillonite composite for ciprofloxacin removal in aqueous media
文章编号: N19072401
期刊: Chemosphere
作者: Ahmed Ashiq, Binoy Sarkar, Nadeesh Adassooriya, Janitha Walpita, Anushka Upamali Rajapaksha, Yong Sik Ok, Meththika Vithanage
更新时间: 2019-07-24
摘要: This study evaluates a novel adsorbent for ciprofloxacin (CPX) removal from water using a composite derived from municipal solid waste biochar (MSW-BC) and montmorillonite (MMT). The composite adsorbent and pristine materials were characterized using powder X-Ray Diffraction (PXRD), Fourier-Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscope (SEM) before and after the adsorption. Batch experiments were conducted to study the mechanisms involved in the adsorption process. Ciprofloxacin sorption mechanisms were interpreted in terms of its pH-dependency and the distribution coefficients. The SEM images confirmed the successful binding of MMT onto the MSW-BC through flaky structure along with a porous morphology. Encapsulation of MMT onto MSW-BC was exhibited through changes in the basal spacing of MMT via PXRD analysis. Results from FTIR spectra indicated the presence of functional groups for both pristine materials and the composite that were involved in the adsorption reaction. The Hill isotherm model and pseudo-second-order and Elovich kinetic models fitted the batch sorption data, which explained the surface heterogeneity of the composite and cooperative adsorption mechanisms. Changes made to the MSW-BC through the introduction of MMT, enhanced the active sites on the composite adsorbent, thereby improving its interaction with ionizable CPX molecules giving high sorption efficiency.
图文摘要:

24478. 题目: Sunflower stalk–derived biochar enhanced thermal activation of persulfate for high efficient oxidation of p-nitrophenol
文章编号: N19072314
期刊: Environmental Science and Pollution Research
作者: Peng Sun, Kaikai Zhang, Jianyu Gong, Aimal Khan, Yu Zhang, Md. Suzaul Islama, Yanrong Zhang
更新时间: 2019-07-23
摘要: Sunflower stalk–derived biochars (BC) were prepared at various temperatures (i.e., 500, 650, and 1000 °C) and demonstrated as a highly efficient catalyst in persulfate (PS) activation for the oxidation of p-nitrophenol (PNP) at 60 °C. The apparent PNP oxidation rate constant in the BC500 (0.1543 L mol⁻¹ S⁻¹), BC650 (0.6062 L mol⁻¹ S⁻¹), or BC1000 (2.1379 L mol⁻¹ S⁻¹) containing PS system was about 2, 8 and 28 times higher than that in PS/PNP (0.0751 L mol⁻¹ S⁻¹) system, respectively. The effect of reaction temperature on PNP oxidation was also investigated. Furthermore, the radical quenching tests and electron paramagnetic resonance spectroscopy (EPR) were employed to investigate the sulfate and hydroxyl radicals for PNP oxidation. The Raman results suggested that the defective sites on biochars possess vital role for oxidation of PNP in PS system. The possible activation pathway of PS/BC was proposed that the defective sites on BC were involved for weakening the O–O bond in PS and subsequently cleaving O–O bond by heat to generate sulfate radical. The oxidation of PNP at low concentration (below 100 μg L⁻¹) was completely removed in urban wastewater by PS/BC system within 30 min. This work would provide new insights into PS activation by BC catalyst and afford a promising method for organic pollutant removal in high-temperature wastewater.

24479. 题目: Performance of Physically and Chemically Activated Biochars in Copper Removal from Contaminated Mine Effluents
文章编号: N19072313
期刊: Water, Air, & Soil Pollution
作者: Flavia Lega Braghiroli, Hassine Bouafif, Carmen Mihaela Neculita, Ahmed Koubaa
更新时间: 2019-07-23
摘要: The increasing global demand for metals and minerals justifies the intensive study of treatment options for contaminated mine effluents. The present study evaluated the conversion of wood residues into physically and chemically activated biochars and their subsequent use in the treatment of Cu in synthetic and actual contaminated mine drainage. First, wood residues were converted into biochar by fast pyrolysis. Then, physical (using steam or CO₂) or chemical (using KOH) activation was carried out in a homemade pilot-scale furnace. After activation, highly microporous (KOH materials) and micro/mesoporous activated biochars (CO₂ and steam materials) were obtained. Batch adsorption testing was first conducted with synthetic effluents. Results showed that CO₂-activated biochar was the most Cu effective adsorbent (99% removal) at low concentrations (5–20 mg L⁻¹). The mechanisms of Cu²⁺ adsorption involved physical and chemisorption for biochars and CO₂-activated biochar, while chemisorption for KOH-activated biochars was probably due to the high proportion of functional groups connected to their surface. In multi-metal acid mine drainage, metal adsorption capacities deteriorated for most of the materials, probably due to the effects of ion competition. However, KOH-activated biochar decreased Cu²⁺ concentrations to below the authorized monthly mean allowed by Canadian law (0.3 mg L⁻¹) and decreased Co, Pb, and Mn concentrations up to 95%. These findings indicate that high porosity and oxygenated functional groups connected to the surface of activated biochars are important properties for the enhancement of interactions between carbon materials and metals from mine effluents, as well as for their performance improvement in mine drainage treatment.

24480. 题目: Organic phosphorus mineralization characteristics in sediments from the coastal salt marshes of a Chinese delta under simulated tidal cycles
文章编号: N19072312
期刊: Journal of Soils and Sediments
作者: Junhong Bai, Lu Yu, Xiaofei Ye, Zibo Yu, Yanan Guan, Xiaowen Li, Baoshan Cui, Xinhui Liu
更新时间: 2019-07-23
摘要: Purpose: Sediment organic phosphorus (OP) mineralization plays an important role in phosphorus cycling in coastal salt marshes. However, information on OP mineralization characteristics in sediments under tidal cycles is limited. Materials and methods: Sediment cores were collected from salt marshes which were exposed to tidal cycles. A laboratory manipulation experiment was conducted under simulated tidal flooding cycles. After the completion of each incubation experiment, the inorganic phosphorus (IP) and OP fractions were analyzed and net phosphorus mineralization rates were calculated to investigate the sediment OP mineralization process. Sediment microbial characteristic and chemical properties were determined to identify factors that affect the mineralization of OP in the Yellow River Delta. Results and discussion: During the first 2 days of incubation, the tidal cycles significantly increased the microbial biomass in the sediments, which accelerated the assimilation of IP by microorganisms and the transformation of IP into OP in their bodies, thereby causing a significant increase in OP in the sediments. After 2 days of incubation, the mineralization and immobilization of OP entered the adaptation stage and gradually reached the dynamic balance of various phosphorus fractions in sediments. The path analysis showed that microbial biomass phosphorus and carbon (MBP and MBC) and the activity of alkaline phosphatase (AKP) are the direct factors influencing OP mineralization in sediments. The indirect effects of soil organic matter (SOM), water content (WC), exchangeable aluminum (Al₀), and exchangeable iron (Fe₀) on net phosphorus mineralization rate were relatively high. Conclusions: In the laboratory experiments, we showed that the recovery of tidal cycles caused a fluctuation in OP mineralization and immobilization in sediments, which reached equilibrium over time. The tidal effect was conducive to maintaining the stability of phosphorus in sediments of coastal salt marshes. The findings of this study can contribute to protecting water quality and improving primary productivity in coastal salt marshes by regulating the tidal cycles and the key environmental factors (e.g., SOM, WC, Al₀, and Fe₀) influencing OP mineralization.