论文检索

总访问量：4305639次

总访客量：180583人

所有论文

25701. 题目: Seasonality of dissolved organic carbon in the upper Northeast Pacific Ocean
文章编号: N19041709
期刊: Global Biogeochemical Cycles
作者: Mariana B. Bif, Dennis A. Hansell
更新时间: 2019-04-17
摘要: From seasonal cruises in the NE Pacific Ocean during 2017, we (1) determined dissolved organic carbon concentrations; (2) calculated net community production (NCP) from nitrate drawdown, and; (3) established relationships between NCP and seasonal DOC accumulation in the upper 75m. The fraction of NCP that accumulated as DOC, hereafter referred to as the net dissolved production ratio (NDPr), was calculated for several stations during spring and summer. NDPr was a constant ~0.26 at the most oceanic station, Ocean Station Papa (OSP), during different seasons and years. Using nitrate concentration profiles obtained from Bio‐Argo floats during 2009‐2018 operating near OSP, we calculated NCP at high temporal resolution and then applied the 0.26 constant in order to (4) estimate DOC variability for the 9‐year period. We found strong seasonality near OSP, with NCP maxima during summers ranging from 0.3‐2.9 mol C m^‐2 and surface DOC concentrations estimated to from 56 μmol kg^‐1 in winters to 73 μmol kg^‐1 in summers. There was a 10‐fold interannual variability in the seasonally‐accumulated inventory of DOC, ranging from 0.078‐0.75 mol C m^‐2. This study reinforces the value of deploying floats equipped with chemical sensors in order to better understand marine biogeochemical cycles, especially when high resolution data cannot be obtained otherwise. Given that ~26% of NCP accumulates as DOC in the central Gulf of Alaska, the remaining balance of ~74% is available for export as sinking biogenic particles.

25702. 题目: Microbial communities and their genetic repertoire mediate the decomposition of soil organic carbon pools in revegetation shrublands in a desert in northern China
文章编号: N19041708
期刊: European Journal of Soil Science
作者: Y. F. Sun, Z. Liu, Y. Q. Zhang, Z. R. Lai, W. W. She, Y. X. Bai, W. Feng, S. G. Qin
更新时间: 2019-04-17
摘要: Revegetation using xerophytic plants in drylands can alter soil microbial community diversity and composition; however, information about the microbial communities and their genetic repertoires that are involved in soil organic carbon (SOC) processes in drylands remain unclear. This study aimed to characterize soil microbial genes and their potential to mediate SOC decomposition in three revegetation shrublands (Artemisia ordosica, Salix psammophila and Caragana microphylla) in the Mu Us Desert of northern China using a SOC mineralization experiment and shotgun metagenome sequencing. Among the three shrublands, the S. psammophila shrubland had the highest cumulative CO₂ emissions and highest rates of mineralization of the slow SOC pool. The mineralization rate of the slow SOC pool and the microbial taxonomic and functional composition displayed a significant correlation. Most C‐degradation genes were assigned to three bacterial phyla, Actinobacteria, Proteobacteria and Acidobacteria. The relative abundance of microbial functional genes involved in degrading recalcitrant C‐complexes was significantly higher in the S. psammophila shrubland, resulting in the slow accumulation of recalcitrant SOC. These results suggest that the microbial functional genes that regulate the decomposition of the SOC pool in dryland shrubland soils may be influenced by shrub species selection. These findings highlight the importance of understanding how microbial catabolic potential mediates the potential for SOC sequestration in different revegetation shrublands in drylands.

25703. 题目: Statistical optimization of glyphosate adsorption by biochar and activated carbon with response surface methodology
文章编号: N19041707
期刊: Chemosphere
作者: Gayana Anjali Dissanayake Herath, Leong Soon Poh, Wun Jern Ng
更新时间: 2019-04-17
摘要: The introduction of glyphosate, found in herbicides, to waterbodies is of concern due to its toxicity and hence potential threat to public health and ecological systems. The present study has compared glyphosate removal from aqueous solution with activated carbon and biochar. Box–Behnken design, and percent contribution with Pareto analysis techniques were used in surface response and efficiency calculations modelled the process conditions and their effects. The adsorption data better fitted the Freundlich isotherm model than the Langmuir model. The rate of glyphosate adsorption was found to follow a pseudo-second-order model. pH of the solutions was regulated by buffering during the adsorption process. Higher efficacy of glyphosate removal was obtained by optimising parameters such as operating pH, initial glyphosate concentration, temperature, adsorbent dose, and contact time. The conditions yielding the best removals were pH 8.0, 0.2 mg/L, 50.0 °C, 11.4 g/L, 1.7 h for activated carbon and pH 5.0, 0.7 mg/L, 50.0 °C, 12.3 g/L, 1.9 h for biochar, for the aforementioned parameters respectively. The maximum removal capacity and efficiency were 0.0173 mg/g and 98.45% for activated carbon, and 0.0569 mg/g and 100.00% for biochar. The test results indicated biochar could be important from the perspective of performance and affordability.

25704. 题目: A simple treatment method for phenylarsenic compounds: Oxidation by ferrate (VI) and simultaneous removal of the arsenate released with in situ formed Fe(III) oxide-hydroxide
文章编号: N19041706
期刊: Environment International
作者: Xiande Xie, Hefa Cheng
更新时间: 2019-04-17
摘要: p-Arsanilic acid (p-ASA) and roxarsone (ROX) are two major phenylarsenic feed additives that are still widely used in many countries, and the land application of animal waste containing these compounds could introduce large quantities of arsenic into the environment. In this study, we proposed a treatment scheme for animal waste that involves leaching of p-ASA/ROX out of the manure first by water, then oxidation by ferrate (Fe(VI)) and removal of the arsenate released by in situ formed Fe(III) oxide-hydroxide. The effects of solution pH, dosage of Fe(VI), solution ionic strength, and matrix species on the treatment performance were systematically evaluated. Initial solution pH values of 4.1 and 2.0 were chosen for the oxidation of p-ASA and ROX, respectively, while efficient arsenate removal could be achieved with relatively small adjustment of the final solution pH (to 4.0). The pH-dependent second-order rate constants for the reactions between ferrate and p-ASA and ROX over the pH range of 2.0–12.0 were estimated to be 7.13 × 10⁵–2.01 × 10⁻¹ and 8.91 × 10³–1.65 × 10⁻¹ M⁻¹ s⁻¹, respectively. The degradation pathways of p-ASA/ROX during ferrate oxidation were proposed based on the inorganic and organic intermediates identified. Depending on the levels of p-ASA/ROX, effective treatment could be achieved through flexible adjustment of the Fe(VI) dosage. p-ASA/ROX (10 mg-As/L) in swine manure leachate could be efficiently treated by ferrate oxidation within 5 min, with the overall arsenic removal efficiency higher than 99.2%. The treatment performance was barely affected by the presence of common ions (K⁺, Ca²⁺, Na⁺, Mg²⁺, SO₄²⁻, NO₃⁻, and Cl⁻), while humic acid, Mn²⁺, Ni²⁺, Fe³⁺, and Co²⁺ inhibited p-ASA/ROX oxidation. The presence of PO₄³⁻ and NH₄⁺ could accelerate the oxidation of p-ASA/ROX, but PO₄³⁻ and humic acid compromised sorptive removal of the released arsenate due to their competitive sorption on the Fe(III) oxide-hydroxide precipitate. Ferrate oxidation is green and fast, and the operation is simple, thus it could serve as a promising and environment-friendly option for mitigating the risk of phenylarsenic feed additives in animal waste.
图文摘要:

25705. 题目: A novel mode of air recycling favored stable operation of the aerobic granular sludge process via calcium accumulation
文章编号: N19041705
期刊: Chemical Engineering Journal
作者: Zhiming Zhang, Yatong Ji, Runjuan Cao, Zhuodong Yu, Xiangyang Xu, Liang Zhu
更新时间: 2019-04-17
摘要: A novel operation mode of aerobic granular sludge (AGS) with air recycling was investigated to enhance the stability of AGS, and three reactors with varied recycling proportions of 0 (R1), 320% (R2) and 740% (R3) were used in this study. The results showed that more calcium accumulated inside aerobic granules in the R2 and R3 reactors with air recycling and compact granules formed with sludge concentration greater than 6.8 g/L and an integrity coefficient less than 0.1. The high-throughput sequencing results indicated that microbes such as Pseudomonas spp., which secreted extracellular polymeric substance (EPS), were obviously enriched in the reactors with air recycling. Principal component analysis (PCA) indicated that calcium was accumulated by higher proportion of CO₂ with air recycling (especially at a recycling proportion of 320%), and bound to poly-guluronic-acid block (GG block) in alginate-like exopolysaccharide (ALE), which had a high binding energy with calcium. The main ALE secretion microbes, Pseudomonas spp., were enriched after the proportion of the GG block in ALE increased and were maintained at a high level. Stable AGS was finally maintained. The results demonstrate the advantage of a novel process including air recycling for aerobic sludge granulation.

25706. 题目: Are Early Triassic extinction events associated with mercury anomalies? A reassessment of the Smithian/Spathian boundary extinction
文章编号: N19041704
期刊: Earth-Science Reviews
作者: Øyvind Hammer, Morgan T. Jones, Elke Schneebeli-Hermann, Bitten Bolvig Hansen, Hugo Bucher
更新时间: 2019-04-17
摘要: High concentrations of mercury, possibly connected with widespread volcanism of the Siberian Traps, have previously been associated with the Smithian/Spathian (Early Triassic) boundary (SSB) in the Sverdrup Basin, Tethyan sections in India and China, as well as with a shallow-water record in western Spitsbergen. We confirm this Hg/TOC anomaly in the deeper water record at Wallenbergfjellet, central Spitsbergen. However, both paleontological age control and carbon isotopes indicate that the Hg anomaly occurred mainly within strata of middle Smithian age. Therefore, this Hg anomaly is unlikely to be directly causally related to mechanisms contributing to the late Smithian global extinction of nektonic faunas. The TOC and trace element data suggest generally more oxygenated conditions during the Smithian compared to the Spathian, which is at odds with the hypothesis that oxygen depletion may have been a global kill mechanism for the SSB extinction. Further work is needed to assess if precise timing and paleogeographic distribution of anoxia shows any consistent pattern or not during the Smithian and Spathian. The very abrupt lower limb of the positive carbon isotope excursion (CIE) and the coarser grain size immediately below the boundary between the Lusitaniadalen Member and the Vendomdalen Member indicate a substantial stratigraphic gap of latest Smithian age, a previously neglected signal shared with many other boreal SSB sections. Ammonoid age control also indicates that the onset of the late Smithian gap in the high latitudes was earlier than in the Tropics. The gradual end of the positive CIE contrasts with the frequent spike shape observed in tropical shelf records and is definitively earliest Spathian in age. The middle Smithian Hg anomaly in the Boreal record is only visible in the Hg/TOC values, and is associated with a possible shift in organic matter type from terrestrial to marine in the case of Spitsbergen. This suggests that the middle Smithian Hg/TOC anomaly in Spitsbergen may not unequivocally originate from volcanism, and calls for additional caution before interpreting Hg spikes as a volcanic proxy.

25707. 题目: Terrestrial organic matter increases zooplankton methylmercury accumulation in a brown-water boreal lake
文章编号: N19041703
期刊: Science of The Total Environment
作者: Amanda E. Poste, Cathrine Skaar Hoel, Tom Andersen, Michael T. Arts, Per-Johan Færøvig, Katrine Borgå
更新时间: 2019-04-17
摘要: Increases in terrestrial organic matter (tOM) transport from catchments to boreal lakes can affect methylmercury (MeHg) accumulation in aquatic biota both directly by increasing concentrations of aqueous MeHg, and indirectly through effects on MeHg bioavailability and on energy pathways in the lower food web. We carried out a detailed seasonal study of water chemistry, zooplankton diet, and MeHg accumulation in zooplankton in two lakes with contrasting tOM concentrations. Between-lake differences explained 51% of the variability in our water chemistry data, with no observed effect of season or sampling depth, contrary to our expectations. Higher tOM was correlated with higher aqueous Hg concentrations, lower areal pelagic primary productivity, and an increased contribution of terrestrial particles to pelagic particulate organic matter. Based on dietary marker analysis (δ¹³C, δ¹⁵N, and fatty acid [FA] composition), zooplankton diet was strongly linked to feeding mechanism, with dietary reliance on phytoplankton highest in the selective-feeding calanoid copepods, and lowest in filter feeding cladocerans. Zooplankton dietary reliance on phytoplankton and their concentrations of high-quality lipids, including polyunsaturated fatty acids, were higher in the clear-water lake than in the brown-water lake, where bacterial and terrestrial food sources were more prevalent. MeHg was highest in zooplankton from the brown-water lake, with highest concentrations in the 200–500 μm zooplankton size fraction for both lakes. Contrary to our expectations, there was no effect of season on zooplankton dietary markers or MeHg. Our results suggest that, overall, higher tOM results in higher MeHg concentrations in water and zooplankton, and reduces zooplankton dietary reliance on phytoplankton. Increased tOM thus leads to a decrease in the nutritional quality of zooplankton (i.e. higher MeHg concentrations, and lower concentrations of essential fatty acids), which may cascade up the food web with negative implications for higher trophic levels.
图文摘要:

25708. 题目: Improved dewaterability of anaerobically digested sludge and compositional changes in extracellular polymeric substances by indigenous persulfate activation
文章编号: N19041702
期刊: Science of The Total Environment
作者: Tahir Maqbool, Jinwoo Cho, Jin Hur
更新时间: 2019-04-17
摘要: In this study, an indigenous activation of persulfate by iron-bearing minerals was examined using peroxymonosulfate (PMS) and peroxydisulfate (PDS) for the dewaterability and extracellular polymeric substances (EPS) composition of anaerobically digested sludge (ADS). Iron minerals originally present in the ADS seemed to operate as an initiator of the persulfate activation, which was indicated by an increase in the total dissolved iron in the supernatant. The PMS showed higher performance in improving the ADS dewaterability compared to the PDS, with more reduction in the average microbial flocs size. The extracted EPS consisted of three different fluorescent components of tryptophan-like (C1), humic-like (C2), and fulvic-like (C3) components. In the tightly bound (TB)-EPS, two humic-like components (C2 and C3), which were resistant to degradation, exhibited a strong linkage with dewaterability; whereas, in both the PMS and the PDS systems, the C1 was preferentially degraded by the radical-based oxidation, with a greater extent for the PMS-based treatments. The results showed that prior to the actual EPS degradation, the produced radicals were initially involved in cell disruption. The SEC results during the oxidation clearly demonstrated the degradation of a large-sized biopolymer fraction, followed by the production of relatively small sized molecules. They also revealed in the TB-EPS a close association between the ADS dewaterability and the degradation of humic substances.
图文摘要:

25709. 题目: Effects of catchment area and nutrient deposition regime on phytoplankton functionality in alpine lakes
文章编号: N19041701
期刊: Science of The Total Environment
作者: Coralie Jacquemin, Céline Bertrand, Evelyne Franquet, Stéphane Mounier, Benjamin Misson, Benjamin Oursel, Laurent Cavalli
更新时间: 2019-04-17
摘要: High mountain lakes are a network of sentinels, sensitive to any events occurring within their waterbodies, their surrounding catchment and their airshed. In this paper, we investigate how catchments impact the taxonomic and functional composition of phytoplankton communities in high mountain lakes, and how this impact varies according to the atmospheric nutrient deposition regime. For two years, we sampled the post snow-melt and the late summer phytoplankton, with a set of biotic and abiotic parameters, in six French alpine lakes with differing catchments (size and vegetation cover) and contrasting nitrogen (N) and phosphorus (P) deposition regimes. Whatever the nutrient deposition regime, we found that the lakes with the smallest rocky catchments showed the lowest functional richness of phytoplankton communities. The lakes with larger vegetated catchments were characterized by the coexistence of phytoplankton taxa with more diverse strategies in the acquisition and utilization of nutrient resources. The nutrient deposition regime appeared to interact with catchment characteristics in determining which functional groups ultimately developed in lakes. Photoautotroph taxa dominated the phytoplankton assemblages under high NP deposition regime while mixotroph taxa were even more favored in lakes with large vegetated catchments under low NP deposition regime. Phytoplankton functional changes were likely related to the leaching of terrestrial organic matter from catchments evidenced by analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope ratios in seston and zooplankton. Plankton δ¹⁵N values indicated greater water–soil interaction in lakes with larger vegetated catchments, while δ¹³C values indicated the effective mineralization of the organic matter in lakes. The role played by catchments should be considered when seeking to determine the vulnerability of high altitude lakes to future changes, as catchments' own properties will vary under changes related to climate and airborne contaminants.
图文摘要:

25710. 题目: Study on the efficiency of ultrafiltration technology in dealing with sudden cadmium pollution in surface water and ultrafiltration membrane fouling
文章编号: N19041609
期刊: Environmental Science and Pollution Research
作者: Qian Meng, Jun Nan, Zhenbei Wang, Xiaoyu Ji, Fangmin Wu, Bohan Liu, Qiliang Xiao
更新时间: 2019-04-16
摘要: In this paper, the application of ultrafiltration (UF) technology to treat cadmium (Cd) pollution in surface waters is investigated. The effect of the UF membrane molecular weight cut-off (MWCO), Cd ion (Cd²⁺) concentration, solution pH and ionic strength on the removal, and mass balance of Cd were explored. In addition, the effect of the solution pH on UF membrane fouling was analyzed. The results indicated that UF membranes with a low MWCO resulted in an improved Cd removal rate. In addition, as the Cd²⁺ concentration in feedwater increased, the Cd removal rate decreased, while the Cd concentration in the permeate increased. Since the solution pH and ionic strength had a notable impact on the Cd removal rate, a high pH value and low ionic strength led to a higher removal rate of Cd. Under optimal Cd removal conditions, UF reduced the influent Cd concentration from 1.0 to 0.019 mg/L. For membrane fouling, increasing the solution pH led to more serious membrane fouling. This phenomenon was the result of Cd²⁺ reacting with OH⁻ and forming a Cd (OH)₂ precipitate. The precipitate and humic acid formed compact cakes on the membrane surface and blocked membrane pores. These results provided adequate evidence for the higher removal of Cd with increasing solution pH. In addition, SEM images under different pH conditions were in agreement with the conclusion mentioned above, which provided further support for the effect of the solution pH on Cd removal and membrane fouling.

25711. 题目: Competition/Cooperation between Humic Acid and Graphene Oxide in Uranyl Adsorption Implicated by Molecular Dynamics Simulations
文章编号: N19041608
期刊: Environmental Science & Technology
作者: Tu Lan, Jiali Liao, Yuanyou Yang, Zhifang Chai, Ning Liu, Dongqi Wang
更新时间: 2019-04-16
摘要: Molecular dynamics (MD) simulations were performed to investigate the influence of curvature and backbone rigidity of an oxygenated surface, here graphene oxide (GO), on its adsorption of uranyl in collaboration with humic acid (HA). The planar curvature of GO was found to be beneficial in impeding the folding of HA. This, together with its rigidity that helps stabilize the extended conformation of HA, offered rich binding sites to interact with uranyl with only marginal loss of binding strength. According to our simulations, the interaction between uranyl and GO was mainly driven by electrostatic interactions. The presence of HA not only provided multiple sites to compete/cooperate with GO for adsorption of free uranyl but also interacted with GO acting as a “bridge” to connect uranyl and GO. The potential of mean force (PMF) profiles implied that HA significantly enhanced the interaction strength between uranyl and GO and stabilized the uranyl-GO complex. Meanwhile, GO could reduce the diffusion coefficients of uranyl and HA and retard their migrations in aqueous solution. This work provides theoretical hints on the GO-based remediation strategies for the sites contaminated by uranium or other heavy metal ions and oxygenated organic pollutants.
图文摘要:

25712. 题目: Seasonal dynamics and depth distribution of belowground biomass carbon and nitrogen of extensive grassland and a Miscanthus plantation
文章编号: N19041607
期刊: Plant and Soil
作者: Christopher Poeplau, Kai Germer, Kai-Uwe Schwarz
更新时间: 2019-04-16
摘要: Background and aims: Belowground carbon (C) inputs are a major source of soil organic carbon (SOC) in terrestrial ecosystems, and substrate C:N ratios drive SOC stabilisation. In perennial systems, quantitative information on seasonal dynamics of belowground biomass is scarce, but necessary, e.g. to improve SOC modelling and representative sampling. Methods: Seasonal dynamics and depth distribution of belowground biomass C and N of extensive grassland and Miscanthus on sandy soil were estimated. Core samples (1 m depth) were taken six times in 1 year. Miscanthus-derived SOC was quantified using ¹³C natural abundance. Results: Grassland and Miscanthus differed strongly in belowground biomass C (2.5 ± 0.3 vs. 7.3 ± 1.1 Mg ha⁻¹) and C:N ratios (28.6 ± 0.5 vs. 60 ± 3.3). Peak grassland belowground biomass C and N stocks occurred in summer, while those of rhizomatous Miscanthus were in winter due to different strategies of resource allocation. Grassland roots showed a strong seasonal pattern of C:N ratios, indicating N remobilisation. Miscanthus-derived topsoil SOC was low relative to the high belowground biomass, indicating a slow transfer of rhizome carbon to bulk SOC. Conclusions: Representative belowground biomass sampling of perennials should take seasonal dynamics into account, especially in system comparisons. Furthermore, C inputs from rhizome and roots should be estimated separately owing to likely differences in turnover times.

25713. 题目: Two years impacts of rapeseed residue and rice straw biochar on Pb and Cu immobilization and revegetation of naturally co-contaminated soil
文章编号: N19041606
期刊: Applied Geochemistry
作者: Abdus Salam, Saqib Bashir, Imran Khan, Hongqing Hu
更新时间: 2019-04-16
摘要: Biochar continues to gain significant interest in remediation and revegetation of agricultural soils contaminated with potentially toxic elements. Two-year impacts of rapeseed residue and rice straw biochars on Pb and Cu immobilization and revegetation of naturally co-contaminated soil were studied. The extraction techniques namely European Community Bureau of Reference (BCR) sequential extraction procedure, the toxicity characteristics leaching procedure (TCLP), and CaCl₂ extraction were performed to assess Pb and Cu mobility following biochar incorporation. The obtained results revealed that soil pH mostly sustained, with a slight increase of 0.2 units on average. Sequential extraction results exhibited a substantial reduction in the acid soluble forms of Pb and Cu by 57.56% and 54.18% respectively in two years. The immobilized Pb and Cu were effectively transformed into residual (stable) forms; accordingly, the phytoavailable pools of Pb and Cu were reduced after adding biochar. The concentration of Pb and Cu in plants were significantly decreased by 40.81% and 56.14% respectively, with no noticeable variations observed in dry wheat biomass. Due to their stability, rapeseed residue and rice straw biochars produced at high temperature were more effective in immobilizing Pb and Cu as compared to low-temperature biochars. The varying efficiencies of the biochars to immobilize Pb and Cu were attributed to the composition and the degree of ageing of biochars in the amended soils.

25714. 题目: Effects of nitrate dosing on the migration of reduced sulfur in black odorous river sediment and the influencing factors
文章编号: N19041605
期刊: Chemical Engineering Journal
作者: Hongbin Yin, Pan Yang, Ming Kong
更新时间: 2019-04-16
摘要: At present, nitrates were widely used to remediate sulfur-rich sediment in black odorous rivers. However, the optimal nitrate dosage and influencing factors during remediation have not been fully investigated. In this study, various nitrate dosages and possible influencing factors were investigated for their efficiency in treating sulfur-rich sediment. The results indicated that acceptable remedial efficiency (the percentage of acid volatile sulfide (AVS) oxidation and the residual ammonium production) can be achieved when 1.6 times the theoretical nitrate dosage is used. Large amounts of AVS cannot be oxidized if too little nitrate is used and will regenerate after several days of remediation. Conversely, high concentrations of ammonium will form if too much nitrate is used. The results of this study indicated that a rapid AVS oxidation rate will be achieved in higher temperatures; no significant treatment efficiency was found when temperatures were in the range of 15–35 °C. Organic matter slowed the rate of nitrate reduction but did not affect its remedial efficiency for AVS oxidation in sediment. A high concentration of ferrous iron primarily influenced nitrate treatment efficiency in the oxidation of AVS in sediment, simultaneously causing the production of a high ammonium concentration. This study once again proved that microbial mediation of the autotrophic sulfide-driven denitrification dominates AVS oxidation in sediment. This study indicated that a universal nitrate dosage calculation equation should be established, and that factors such as ferrous iron concentration should be considered in future remediation of black odorous rivers.

25715. 题目: A review on biochar modulated soil condition improvements and nutrient dynamics concerning crop yields: Pathways to climate change mitigation and global food security
文章编号: N19041604
期刊: Chemosphere
作者: T.J. Purakayastha, T. Bera, Debarati Bhaduri, Binoy Sarkar, Sanchita Mandal, Peter Wade, Savita Kumari, Sunanda Biswas, Manoj Menon, H. Pathak, Daniel C.W. Tsang
更新时间: 2019-04-16
摘要: The beneficial role of biochar on improvement of soil quality, C sequestration, and enhancing crop yield is widely reported. As such there is not much consolidated information available linking biochar modulated soil condition improvement and soil nutrient availability on crop yields. The present review paper addresses the above issues by compilation of world literature on biochar and a new dimension is introduced in this review by performing a meta-analysis of published data by using multivariate statistical analysis. Hence this review is a new in its kind and is useful to the broad spectrum of readers. Generally, alkalinity in biochar increases with increase in pyrolysis temperature and majority of the biochar is alkaline in nature except a few which are acidic. The N content in many biochar was reported to be more than 4% as well as less than 0.5%. Poultry litter biochar is a rich source of P (3.12%) and K (7.40%), while paper mill sludge biochar is higher in Ca content (31.1%) and swine solids biochar in Zn (49810 mg kg⁻¹), and Fe (74800 mg kg⁻¹) contents. The effect of biochar on enhancing soil pH was higher in Alfisol, Ferrosol and Acrisol. Soil application of biochar could on an average increase (78%), decrease (16%), or show no effect on crop yields under different soil types. Biochar produced at a lower pyrolysis temperature could deliver greater soil nutrient availabilities than that prepared at higher temperature. Principal component analysis (PCA) of available data shows an inverse relationship between [pyrolysis temperature and soil pH], and [biochar application rate and soil cation exchange capacity]. The PCA also suggests that the original soil properties and application rate strongly control crop yield stimulations via biochar amendments. Finally, biochar application shows net soil C gains while also serving for increased plant biomass production that strongly recommends biochar as a useful soil amendment. Therefore, the application of biochar to soils emerges as a ‘win-win strategy’ for sustainable waste management, climate change mitigation and food security.

25716. 题目: Contribution of zooplankton faecal pellets to carbon transport of the mesopelagic layers in the polynya region of Prydz Bay, Antarctica
文章编号: N19041603
期刊: Estuarine, Coastal and Shelf Science
作者: Guang Yang, Zhengbing Han, Jianming Pan, Konglin Zhou, Yanqing Wang, Chaolun Li
更新时间: 2019-04-16
摘要: Seasonal changes in the zooplankton swimmer (those actively swimming into sediment traps) and faecal pellet contribution to particulate organic carbon (POC) were analysed based on sediment trap samples deployed at 450 m in the polynya region of Prydz Bay during March 2013–February 2014. The zooplankton swimmer flux ranged from 6.18 ind m⁻² day⁻¹ to 20.00 ind m⁻² day⁻¹ and pteropods (mainly Limacina helicina) were the most abundant group. Part of the L. helicina population could make a large contribution to the organic carbon flux by passive sinking after death during the austral autumn and winter. The potential contribution of sinking L. helicina to the POC flux could reach 15.21% during winter. Four types of faecal pellets were found: cylindrical, round, ellipsoidal and ovoid. The faecal pellet carbon flux (0.01–4.36 mg C m⁻² day⁻¹) contributed 5.54%–62.00% of the POC flux. Cylindrical faecal pellets, which had low abundance in winter but higher abundance in the early austral summer, were attributed to the ice krill Euphausia crystallorophias. The faecal pellet carbon flux showed a high value (1.03 mg C m⁻² day⁻¹) but made little contribution (9.18%) to the POC flux during early summer (December) in relation to the large amount of ungrazed algae. The high faecal pellet carbon flux (1.98 mg C m⁻² day⁻¹) during mid-summer (January) made the greatest contribution (62.00%) to the POC flux. During autumn and winter, the faecal pellet carbon flux was low and ovoid pellets (mostly generated by L. helicina) were the most abundant. The occurrence of intact fresh pellets and faecal fluff (degraded faecal pellets) in the winter samples suggested that zooplankton activities (diel vertical migration and fragmentation of faecal pellets) had an effect on the carbon flux. The results demonstrated that zooplankton could play an important role in the carbon flux in the polynya region of Prydz Bay.

25717. 题目: Partial substitution of chemical fertilizer with organic amendments affects soil organic carbon composition and stability in a greenhouse vegetable production system
文章编号: N19041602
期刊: Soil and Tillage Research
作者: Haoan Luan, Wei Gao, Shaowen Huang, Jiwei Tang, Mingyue Li, Huaizhi Zhang, Xinping Chen
更新时间: 2019-04-16
摘要: Understanding soil organic carbon (SOC) composition and stability is necessary for long-term carbon (C) sequestration. Fertilization is known to modify SOC stability and composition; however, inconsistent results have been reported. Here, we evaluated the changes in SOC composition and stability through multiple methods in an 8-year fertilization experiment under greenhouse vegetable production (GVP) systems in Tianjin, China. This experiment was designed to supply an equivalent amount of nutrients (N, P₂O₅ and K₂O) but variable amount of C through different exogenous organic resources (ORs) input. Five treatments were included based on substitution of chemical fertilizer nitrogen (N) with different exogenous ORs: no N (no nitrogen inputs), 4/4CN (CN, nitrogen in chemical fertilizer), 2/4CN + 2/4 MN (MN, nitrogen in pig manure, high-quality ORs), 2/4CN + 2/4SN (SN, nitrogen in corn straw, low-quality ORs) and 2/4CN + 1/4 MN+1/4SN. Organic fertilization strategies promoted SOC accumulation and reduced SOC stability by increasing labile C fractions, whereas chemical fertilizer alone had a negative effect on SOC accumulation by consuming labile C fractions but enhanced SOC stability. Notably, the characteristics of high temperature, nutrient availability and C inputs in organically managed soils in GVP systems weaken the influence of ORs quality on SOC stability. Consequently, high doses of C inputs (11.5 and 18.5 Mg ha^–1 year^–1 in 2/4CN + 1/4 MN+1/4SN and 2/4CN + 2/4SN treatments) induced lower SOC stability than low doses of C inputs (4.5 Mg ha^–1 year^–1 in the 2/4CN + 2/4 MN treatment), irrespective of ORs quality. In addition, strong correlations were found between SOC thermal characteristics and SOC chemical and ¹³C NMR spectral properties, indicating that thermal analysis techniques can characterize SOC stability effectively.
图文摘要:

25718. 题目: Biogenic aggregation intensifies soil improvement caused by manures
文章编号: N19041601
期刊: Soil and Tillage Research
作者: Thadeu Rodrigues de Melo, Marcos Gervasio Pereira, Graziela Moraes de Cesare Barbosa, Eduardo Carvalho da Silva Neto, Avacir Casanova Andrello, João Tavares Filho
更新时间: 2019-04-16
摘要: The use of manures as organic fertilizers commonly improves soil chemical and structural attributes. We investigated the effect of biogenic aggregation on the structural and chemical dynamics of a Rhodic Ferralsol after nine continuous years of chicken manure or swine liquid manure application. The biogenic aggregation increased nutrient availability, neutralized acidity, and increased organic matter content. Additionally, the proportion of pores with a diameter higher than 0.100 mm was increased by biogenic aggregation. The intensity of this improvement depended on the manure nutrient content, and the rate of biogenic aggregation depended on the carbon input provided by the manure. However, aggregates with higher base saturations were more susceptible to dispersion and such aggregates, therefore, need to be protected from mechanical disrupting agents.

25719. 题目: Insights into the effects of acidification on sewage sludge dewaterability through pH repeated adjustment
文章编号: N19041503
期刊: Chemosphere
作者: Hua Wei, Yunong Tang, Aimin Li, Hu Yang
更新时间: 2019-04-15
摘要: Sludge acidification is a popular and efficient pretreatment method for improving sludge dewaterability. To explore the mechanisms of sludge acidification deeply and provide a theoretical basis for practical application, sewage sludge was repeatedly treated by acidification conditioning. The sludge pH was continuously adjusted from 7.0 to 3.0, then back to 7.0, and to 3.0 again in this study. When the sludge pH returned to a neutral condition, the sludge dewaterability was further deteriorated. However, after the second acidification conditioning, the sludge dewaterability was improved to the same level as that at the first conditioning. These experimental facts were due to two acidification effects. One was that acidification can efficiently destroy the structure of sludge flocs, thereby causing the degradation of extracellular polymeric substances (EPSs) and release of trapped water. Furthermore, some internal EPSs were released into the outer layer. The other was protonation effect, which can effectively compress the released EPSs, especially protein-like matters (PN) therein. These two combined effects caused a good sludge dewaterability. However, the former was irreversible, whereas the latter was reversible. When the pH of acidified sludge was readjusted to 7.0, the protonation effect weakened, thereby the original compressed EPS released into the outer layer of sludge and the PN content in soluble EPS fraction increased near five times, resulting in considerable deterioration of sludge dewaterability. The negative effects of released organic matters by acidification were often concealed and neglected due to protonation, thereby causing the reversal of dewatering performance in practice when the sludge pH was fluctuated.
图文摘要:

25720. 题目: Adsorption/desorption behavior of cationic and anionic dyes by biochars prepared at normal and high pyrolysis temperatures
文章编号: N19041502
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Jong-Hwan Park, Jim J. Wang, Yili Meng, Zhuo Wei, Ronald D. DeLaune, Dong-Cheol Seo
更新时间: 2019-04-15
摘要: The purpose of this study was to determine the properties of biochar prepared at higher than normal biochar production temperature and to evaluate adsorption/desorption characteristics for three commonly used dyes of different charge and molecular nature: Methylene Blue (MB), Orange G (OG) and Congo Red (CR). The switchgrass-biochar was prepared at common pyrolysis temperature of 600 °C (SB600) and higher than normal temperature of 900 °C (SB900). The results showed that the carbon content of the two biochars was similar, but most carbon in SB900 was graphitized based on FTIR and XRD observation. Dye adsorption isotherms by SB600 and SB900 was well described Langmuir model with maximum adsorption capacity of MB, OG and CR being 37.6, 8.2 and 8.0 mg/g for SB600 and 196.1, 38.2 and 22.6 mg/g for SB900, respectively. The adsorption kinetics of dyes by both biochars were well described by pseudo-second order model. In addition, intraparticle diffusion model showed that MB adsorption was predominantly by inner pore diffusion rather than by outer boundary, while OG and CR were more adsorbed by the outer boundary. These results indicated that the strong dye adsorption by SB900 compared to SB600 was due to the significantly enhanced surface area at the high pyrolysis temperature. Additionally, the greater adsorption of cationic MB by SBs than that of anionic OG and CR was attributable to the small molecular weight, favorable electrostatic property, and strong π-π interaction of the former with biochar surface as opposed to the latter. Overall, the SB900 maintained > 85% adsorption of maximum capacity even after four adsorption-desorption consecutive cycles and could be used as an effective adsorbent for cationic dye removal from wastewater.
图文摘要: