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24561. 题目: Nutrients and heavy metals mediate the distribution of microbial community in the marine sediments of the Bohai Sea, China
文章编号: N19092004
期刊: Environmental Pollution
作者: Meiqing Lu, Xin Luo, Jiu Jimmy Jiao, Hailong Li, Xuejing Wang, Jingyan Gao, Xiaolang Zhang, Kai Xiao
更新时间: 2019-09-20
摘要: The Bohai Sea, one of the largest marginal seas in China, is extensively influenced by human and industrial activities. The pollutant loads from anthropogenic activities have induced severe ecological problems. The study investigates the physicochemical characteristics of seawater and sediments in Bohai Bay and Laizhou Bay of the Bohai Sea. The diversity and composition of microbial community in sediments are analyzed by 16S rRNA gene amplicon sequencing. The sequencing results present 16 phyla and 31 classes from the samples. Proteobacteria constituted a dominant phylum, of which the classes of Gamma-, Delta-, and Epsilon-are predominant sub-divisions. Nitrogen, phosphorus, and sulfur cycling related microbes present high abundance in both bays. The metabolism of organic matters is the main factor that influences the distribution of microbial communities in Bohai Bay, while the inflow of Yellow River is the dominant factor that influences the distribution of microbial communities in Laizhou Bay. Sulfur oxidizing process is expected to be positively influenced by heavy metals, while ammonia (NH4+) oxidizing process is prone to be negatively affected by heavy metals in both bays. Microbial communities in the offshore sediments of Laizhou Bay and the majority microbial communities in Bohai Bay sediments are subject to similar predominant controlling factors. This phenomenon is likely ascribed to ocean circulation. The results of this study can provide constructive guidelines on ecosystem management of marginal seas in Bohai and elsewhere.
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24562. 题目: Adsorption and fractionation of Pt, Pd and Rh onto inorganic microparticles and the effects of macromolecular organic compounds in seawater
文章编号: N19092003
期刊: Environmental Pollution
作者: Kai Liu, Xuelu Gao
更新时间: 2019-09-20
摘要: Adsorption and fractionation of Pt, Pd and Rh (defined here as platinum group elements, PGEs) onto the representative inorganic microparticles, including Fe2O3, MnO2, CaCO3, SiO2, Al2O3 and kaolinite in seawater were investigated. The effects of macromolecular organic compounds (MOCs) as the representatives of organic matter, including humic acids (HA), bovine serum albumin (BSA) and carrageenan, on the adsorption were also studied considering that organic matter is ubiquitous in seawater and indispensable to marine biogeochemical cycles. In the absence of MOCs, the representative mineral particles Fe2O3 and MnO2 had the strongest interaction with PGEs. The adsorption of PGEs onto the representative biogenic particles SiO2 and CaCO3 and lithogenic particles Al2O3 and kaolinite was similar or weaker than onto the mineral particles. MOCs inhibited the interaction between PGEs and the particles except for Pt and Pd onto the biogenic particles in artificial seawater. This impediment may be closely related to the interaction between particles, MOCs and elements. The partition coefficient (log Kd) of Pt was similar (∼4.0) in the presence of MOCs, indicating that the complexation between Pt and MOCs was less important than hydrolysis or adsorption onto the acid oxide particle surface. Rh tended to fractionate onto the mineral and lithogenic particles in the presence of HA and carrageenan, while Pd was more likely to fractionate onto the biogenic particles. However, BSA enhanced the fractionation tendency of Pd onto the mineral particles. The results indicate that the adsorption behavior of Pd onto inorganic particles was significantly affected by the composition or the type of MOCs. Hence, the interaction between PGEs and inorganic particles may be greatly affected by the macromolecular organic matter in the ocean.
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24563. 题目: Microbial sulfidogenesis of arsenic in naturally contaminated wetland soil
文章编号: N19092002
期刊: Geochimica et Cosmochimica Acta
作者: Magdaléna Knappová, Petr Drahota, Lukáš Falteisek, Adam Culka, Vít Penížek, Jakub Trubač, Martin Mihaljevič, Tomáš Matoušek
更新时间: 2019-09-20
摘要: Microbial sulfidogenesis plays a potentially important role in As biogeochemistry within wetland soils, sediments, and aquifers. This study investigated the effects of microbial sulfidogenesis on As mineralogy in the As-enriched wetland soil found at the natural geochemical anomaly of the Smolotely-Líšnice (Czech Republic) historical gold district. The distribution and speciation of As as a function of soil depth, and the metabolic properties of microbial communities in different sulfidogenic domains were examined by bulk soil as well as pore water analyses, selective chemical extractions, S isotopes, and DNA extractions. Total solid-phase analyses and selective extractions of the soil samples below ∼40 cm showed that As (up to 1.16 g kg–1) and Fe(II) are coupled to S and TOC, and had accumulated to a considerable extent in the exterior parts of NOM fragments (up to 19 wt.% As). Microscale imaging and Raman spectroscopy revealed that As speciation in the NOM exteriors is a combination of realgar (α-As4S4), bonazziite (β-As4S4) and arsenian Fe sulfides, primarily greigite (Fe3S4) and framboidal pyrite (FeS2). The sulfide phases were depleted in the 34S isotope by 6.3-29.4‰ relative to pore water SO42–; thus implying their biologically induced formation. Microbial communities associated with sulfidogenic environments in NOM and bulk soil had variable compositions, although the dissimilative SO42– reduction was usually the main metabolic trait. Relatively low isotopic fractionation in sulfide-rich NOM fragments (6.3-11.6‰) compared to bulk soil (down to -26.1‰) revealed a reservoir effect that developed probably at mm-scales. This indicates formation of sulfide phases in highly localized environments depleted in aqueous SO42– due to strong microbial sulfidogenesis when compared to the transfer rate of the solutes. The very high proportion of fermenting microorganisms in sulfide-rich NOM fragments provided further evidence of strongly reducing conditions, which are a prerequisite for sulfide phase precipitation. We have shown that by the development of suitable conditions for sulfidogenesis, NOM fragments play an active role in As immobilization in an As-enriched wetland soil. Regarding the effectiveness of As sulfidogenesis in shallow wetland soils to remediate groundwater, our findings imply that As contamination may either be limited by the low content of labile organic matter or by the fast transfer of solutes (groundwater flow).
24564. 题目: Calculating 14C mean residence times of inorganic carbon derived from oxidation of organic carbon in groundwater using the principles of 87Sr/86Sr and cation ratio mixing
文章编号: N19092001
期刊: Geochimica et Cosmochimica Acta
作者: Daniel Magnone, Laura A. Richards, Bart E. van Dongen, Charlotte Bryant, Jane A. Evans, David A. Polya
更新时间: 2019-09-20
摘要: The model radiocarbon age of inorganic carbon (IC) in groundwater is a key parameter for understanding groundwater chemical history and physical parameters such as groundwater residence times and flow rates. Current interpretations are based on the principle that bulk IC derives from multiple sources such as oxidation of organic carbon (OC), carbonate dissolution, and soil zone processes as well as from rainwater. Using this principle, multiple adjustment methods have been developed to calculate rainwater-related recharge ages. Of further interest, however, is the radiocarbon age of oxidised OC. This is a key measurement given that OC oxidation controls the mobility of many important geochemical components such as Fe, As, Mn and U. In this instance, conventional approaches tacitly assume that the majority of IC comes from the oxidation of OC and that other sources have a negligible effect on the bulk age. In reality, however, there are multiple source of IC which can all effect bulk radiocarbon ages. We present a new approach to calculate the age of IC derived from a specific source. This approach uses strontium isotopes (87Sr/86Sr) coupled with elemental ratios to trace and quantify the mixing of different sources of IC. We demonstrate the approach by calculating the model radiocarbon age of IC from the oxidation of OC for a case study of an aquifer in the Cambodian lowlands located adjacent to the Mekong river south of Phnom Penh. The results show that, although bulk IC is younger and more isotopically depleted than bulk organic carbon (OC), IC derived from oxidation of OC, has a similar age and isotopic signature to bulk OC. Furthermore, at our site the age of the IC formed from the oxidation of organic carbon predates modelled groundwater flow by at least a millennium indicating that in-aquifer oxidation is an important process, something previously questioned at the site. This highlights the utility of the new approach to disentangling the origin of the sources of bulk IC, so critical to the interpretation of its model radiocarbon age and isotopic signature.
24565. 题目: Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments
文章编号: N19091902
期刊: Global Change Biology
作者: Chiara Ravaglioli, Fabio Bulleri, Saskia Rühl, Sophie J. McCoy, Helen S. Findlay, Stephen Widdicombe, Ana M. Queirós
更新时间: 2019-09-19
摘要: Anthropogenic stressors can alter the structure and functioning of infaunal communities, which are key drivers of the carbon cycle in marine soft sediments. Nonetheless, the compounded effects of anthropogenic stressors on carbon fluxes in soft benthic systems remain largely unknown. Here, we investigated the cumulative effects of ocean acidification (OA) and hypoxia on the organic carbon fate in marine sediments, through a mesocosm experiment. Isotopically labelled macroalgal detritus (13C) was used as a tracer to assess carbon incorporation in faunal tissue and in sediments under different experimental conditions. In addition, labelled macroalgae (13C), previously exposed to elevated CO2, were also used to assess the organic carbon uptake by fauna and sediments, when both sources and consumers were exposed to elevated CO2. At elevated CO2, infauna increased the uptake of carbon, likely as compensatory response to the higher energetic costs faced under adverse environmental conditions. By contrast, there was no increase in carbon uptake by fauna exposed to both stressors in combination, indicating that even a short‐term hypoxic event may weaken the ability of marine invertebrates to withstand elevated CO2 conditions. In addition, both hypoxia and elevated CO2 increased organic carbon burial in the sediment, potentially affecting sediment biogeochemical processes. Since hypoxia and OA are predicted to increase in the face of climate change, our results suggest that local reduction of hypoxic events may mitigate the impacts of global climate change on marine soft‐sediment systems.
24566. 题目: Changes of composition and content of tricyclic terpane, hopane, sterane, and aromatic biomarkers throughout the oil window: A detailed study on maturity parameters of Lower Toarcian Posidonia Shale of the Hils Syncline, NW Germany
文章编号: N19091901
期刊: Organic Geochemistry
作者: Ronghui Fang, Ralf Littke, Laura Zieger, Alireza Baniasad, Meijun Li, Jan Schwarzbauer
更新时间: 2019-09-19
摘要: A total of 30 core samples of organic matter-rich Lower Toarcian shale (Posidonia Shale) were geochemically analyzed to study systematic changes in the quantitative and qualitative composition of specific biomarkers at different thermal maturities ranging from 0.48 to 1.45% vitrinite reflectance (VRr). The samples are derived from 5 wells (Hils Syncline, NW Germany) each representing a different level of maturation (0.48, 0.68, 0.73, 0.88, 1.45 %VRr). In NW Germany, Posidonia Shale was deposited under marine, oxygen-deficient bottom water containing initially high amounts of TOC (above 10%) and marine type I-II kerogen. Upon maturation, organic carbon has been lost and hydrogen index values have decreased. Biomarker ratios reflecting this maturation very well include ratios of short over long-chain n-alkanes, ratios of pristane and phytane over nC17 and nC18, Ts/(Ts+Tm), C29Ts/(C29Ts+C29H), ratios based on DMDBTs, and TA(I)/TA(I+II) ratios (triaromatic steroids). The evolution of different steroid-, hopane-, naphthalene-, phenanthrene- and dibenzothiophene-related parameters is documented and compared to literature.Concentrations of individual hydrocarbons were measured in order to obtain quantitative data on biomarker abundance and their evolution upon maturation. Whereas there is a general trend of increasing biomarker content from immature (0.48 %VRr) to early mature (0.68 %VRr) conditions and of decreasing biomarker content with maturation from 0.68 to 0.88 %VRr, there are some exceptions from this trend, especially at low levels of maturity. Almost no polycyclic biomarkers were detected at the highest maturity level of 1.45 %VRr in well Haddessen, where n-alkanes and aromatic hydrocarbons are predominant. The overall pattern of polycyclic biomarker abundance is not only determined by isomerization and aromatization processes, but mainly by preferential degradation of thermally less stable biomarkers leading to the observed modifications of biomarker maturity parameters.Furthermore, outer and inner sections from the 10 cm wide cores were compared in order to find out, whether 40 years of dry storage in a core repository affected the biomarker parameters. No significant and systematic differences have been observed, with exception of the most mature Haddessen well, where low molecular weight n-alkanes (<nC21) are more abundant in the outer part.
24567. 题目: Iron Isotope Fractionation during Bio- and Photodegradation of Organoferric Colloids in Boreal Humic Waters
文章编号: N19091808
期刊: Environmental Science & Technology
作者: Olga V. Oleinikova, Franck Poitrasson, Olga Yu Drozdova, Liudmila S. Shirokova, Sergey A. Lapitskiy, Oleg S Pokrovsky
更新时间: 2019-09-18
摘要: Biodegradation and photolysis of dissolved organic matter (DOM) in boreal high-latitude waters are the two main factors controlling not only the aquatic fluxes and residence time of carbon but also metal nutrients associated with DOM such as Fe. The DOM is usually present in the form of organic and organomineral colloids, which also account for the majority of dissolved Fe. Here, we use the stable Fe isotope approach to unravel the processes controlling Fe behavior during bio- and photodegradation of colloids in boreal Fe- and DOM-rich humic waters (a stream and a fen). The adsorption of Fe colloids onto heterotrophic bacteria Pseudomonas aureofaciens produced enrichment in +0.4‰ (δ57Fe) in the heavier isotopes of the cell surface relative to the remaining solution. In contrast, long-term assimilation of Fe by live cells yielded preferential incorporation of lighter isotopes into the cells (−0.7‰ relative to aqueous solution). The sunlight-induced oxidation of Fe(II) in fen water led to the removal of heavier Fe isotopes (+1.5 to +2.5‰) from solution, consistent with Fe(III) hydroxide precipitation from Fe(II)-bearing solution. Altogether, bio- and photodegradation of organoferric colloids, occurring within a few days of exposure time, can produce several per mil isotopic excursions in shallow lentic and lothic inland waters of high-latitude boreal regions. Considerable daily scale variations of Fe isotopic composition should therefore be taken into account during the interpretation of the riverine flux of Fe isotopes to the ocean or tracing weathering processes using Fe isotopes in surface waters at high latitudes.
24568. 题目: Land use, not stream order, controls N2O concentration and flux in the upper Mara River basin, Kenya
文章编号: N19091807
期刊: Journal of Geophysical Research: Biogeosciences
作者: R.M. Mwanake, G.M. Gettel, K.S. Aho, D.W. Namwaya, F.O. Masese, K. Butterbach‐Bahl, P.A. Raymond
更新时间: 2019-09-18
摘要: Anthropogenic activities have led to increases in nitrous oxide (N2O) emissions from river systems, but there are large uncertainties in estimates due to lack of data in tropical rivers and rapid increase in human activity. We assessed the effects of land use and river size on N2O flux and concentration in 46 stream sites in the Mara River, Kenya during the transition from the wet (short rains) to dry season, Nov. 2017 – Jan. 2018. Flux estimates were similar to other studies in tropical and temperate systems, but in contrast to other studies, land‐use was more related to N2O concentration and flux than stream size. Agricultural stream sites had the highest fluxes (26.38 ± 5.37 N2O‐N μg m‐2 h‐1) compared to both forest and livestock sites (5.66 ± 1.38 N2O‐N μg m‐2h‐1 and 6.95 ± 2.96 N2O‐N μg m‐2h‐1, respectively). N2O concentrations in forest and agriculture streams were positively correlated to stream carbon dioxide (CO2‐C(aq)) but showed a negative correlation with dissolved organic carbon (DOC), and the DOC:DIN ratio. N2O concentration in the livestock sites had a negative relationship with CO2‐C(aq) and a higher number of negative fluxes. We concluded that in‐stream chemoautotrophic nitrification was likely the main biogeochemical process driving N2O production in agricultural and forest streams, whereas complete denitrification led to the consumption of N2O in the livestock stream sites. These results point to the need to better understand the relative importance of nitrification and denitrification in different habitats in producing N2O and for process‐based studies.
24569. 题目: Transport of cobalt and silver from the ocean to a reef island by seabirds in the South China Sea
文章编号: N19091806
期刊: Journal of Geophysical Research: Biogeosciences
作者: L.Q. Xu, L.B. Wu, Y.H. Zhang, J.J. Zhao
更新时间: 2019-09-18
摘要: Seabirds are typical bio‐vectors, delivering both nutrients and metals across ecosystem boundaries. However, seabird transfer of Ag and Co has not been well documented. Using an ornithogenic sediment core collected from the remote Zhaoshu Island, South China Sea, we investigated potential impacts of seabirds on Ag and Co transportation. These two elements exhibited peak abundance in a guano layer in the sediment profile. Via statistical analyses, Ag, Co and previously identified avian bio‐elements (Cn, Zn, Cd, P, As, Se) had a common source, i.e. guano. Guano input was also partly responsible for the distribution of Y, Ce, La, Sc and U in the bulk sediments. The concentration‐versus‐depth profiles of Mn, Mo, Bi, Rb and W were possibly associated with organic matter.
24570. 题目: From land to the ocean: the interplay between allochthonous and autochthonous contribution to particles in nepheloid layers of the Cariaco Basin, Venezuela
文章编号: N19091805
期刊: Journal of Geophysical Research: Biogeosciences
作者: Laura Lorenzoni, Robert C. Thunell, Claudia R. Benitez‐Nelson, Enrique Montes, Ramón Varela, Yrene Astor, Frank E. Muller‐Karger
更新时间: 2019-09-18
摘要: Lithogenic sediment input to the Cariaco Basin on the eastern Venezuelan shelf is controlled by small mountainous rivers (SMR). The Cariaco Basin is also an area of high phytoplankton productivity as a result of strong Trade Wind‐driven coastal upwelling. Characterizing the sources that supply particulate organic carbon (POC) to the deep Cariaco Basin is important for interpreting the paleoclimate record stored in its sediments. We measured suspended POC in the four main rivers draining into the Caraiaco Basin: the Tuy, Unare, Neveri and Manzanares, between September 2008 and September 2009, and conducted basin‐wide oceanographic cruises in September 2008 (rainy season) and March 2009 (upwelling season). Riverine concentrations of dissolved and particulate organic carbon (DOC and POC, respectively) in the four rivers were comparable to observations made in similar tropical SMR systems (POC was between 0.3‐2 mg C l‐1; DOC was between 100‐300 μM). Within the basin, the geochemical composition of surface particles and bottom nepheloid layers (BNL) changed with season. During the rainy season, the isotopic composition of both surface particles and BNL was characteristic of continentally‐derived material (δ13Corg, ~‐30 ‐ ‐26‰), while during upwelling, the composition shifted to values more typical of marine sources (δ13Corg, ~‐24 ‐ ‐20‰). SMRs represent an important component of the global carbon budget, which are often overlooked in ocean carbon budgets and also in paleoclimate studies of coastal environments.
24571. 题目: Convergence of terrestrial dissolved organic matter composition and the role of microbial buffering in aquatic ecosystems
文章编号: N19091804
期刊: Journal of Geophysical Research: Biogeosciences
作者: Jennifer L. Harfmann, François Guillemette, Karl Kaiser, Robert G.M. Spencer, Chia‐Ying Chuang, Peter J. Hernes
更新时间: 2019-09-18
摘要: Substantial changes in vegetation are expected as global climatic patterns shift, altering terrestrial sources of dissolved organic matter (DOM) entering rivers and streams. Since differences in the chemical composition of plant litters are reflected in the DOM that is leached, changes in riparian vegetation can directly influence the bioavailability of DOM to local aquatic microbial communities. We assessed the degradation dynamics and optical compositional changes of DOM from a variety of vascular plant leachates through microbial and coupled photochemical‐microbial degradation pathways. Initial decay rates ranged from 0.029 ± 0.011 day‐1 (microbial, mixed wetland) to 0.73 ± 0.62 day‐1 (photochemical‐microbial, mixed grasses) and all decay rates decreased to below 0.05 day‐1 after one week, converging below 0.029 day‐1 after two weeks. Overall we found a decrease in leachate optical diversity under microbial and photochemical‐microbial degradation, corresponding to a decrease in degraded leachate sample dispersion using principal component analysis. We show that despite initial variability across DOM leachates, successive degradation promotes kinetic and optical convergence such that, in aquatic environments with long residence times, terrestrial DOM source and composition are much less important on exported DOM composition than historically thought. In these systems, DOM compositional convergence may act as a natural buffer to provide stability of aquatic DOM cycling in the face of future landscape changes.
24572. 题目: Links between microbial processing of organic matter and the thermohaline and productivity features of a temperate river-influenced mediterranean coastal area
文章编号: N19091803
期刊: Estuarine, Coastal and Shelf Science
作者: Mauro Celussi, Luca Zoccarato, Fabrizio Bernardi Aubry, Mauro Bastianini, Raffaella Casotti, Cecilia Balestra, Michele Giani, Paola Del Negro
更新时间: 2019-09-18
摘要: Regions of freshwater influence are affected by a constant interplay of different environmental factors that rule their seasonal and interannual highly variable dynamics. Riverine freshwater discharges alter the buoyancy of the local water masses, generating dynamic fronts and increasing water column stratification and nutrient availability. In such a heterogeneous context the paradigms for biological-physical interactions driving biogeochemical dynamics in the open seas do not always apply. We present here data from 12 surveys spanning 12 years (from 2004 to 2016) in the Po River prodelta area, which is highly representative of the above-described complexity, as it conveys the second largest freshwater discharge to the Mediterranean Sea. In particular, we focused on the microbially-mediated organic matter processing by estimating the numerical abundances of non-pigmented (‘heterotrophic’) and photoautotrophic (Synechococcus) prokaryotes, heterotrophic production and the activity of the exoenzymes beta-glucosidase, alkaline phosphatase and leucine aminopeptidase. The abundance of Synechococcus and heterotrophic prokaryotes as well as microbial activities were positively correlated to temperature and chlorophyll a concentration. Concomitantly, each variable was negatively correlated to salinity. In high-temperature, high salinity and low chlorophyll a samples, the heterotrophic production was limited and deviated from the typical linearity of the Arrhenius' law, suggesting resource limitation rather than temperature control. A multivariate analysis performed to analyze the pattern of organic matter degradation/utilization highlighted 11 distinct clusters of functional diversity. Temperature, salinity and chlorophyll a concentration data alone were able to explain most of the functional cluster separation as evidenced by a regression tree analysis. For freshwater-influenced samples, salinity was the only variable affecting metabolic patterns, whereas in typically marine waters, at salinity ≥37, metabolic profiles were determined by specific combinations of all 3 parameters.
24573. 题目: Recalcitrant carbon for composting of fibrous aquatic waste: Degradation kinetics, spectroscopic study and effect on physico-chemical and nutritional properties
文章编号: N19091802
期刊: Journal of Environmental Management
作者: Mayur Shirish Jain, Siddhartha Paul, Ajay S. Kalamdhad
更新时间: 2019-09-18
摘要: Biochar, a recalcitrant carbon, is known to enhance organic matter degradation and improve physical properties. The objective of the study is to examine the probable effect of biochar addition during composting of a fibrous aquatic waste, i.e., water hyacinth though degradation kinetics and spectroscopic (FTIR and PXRD) analysis. Four dosages of biochar (0, 2.5, 5, and 10% w/w) were mixed to a mixture of water hyacinth, cow-dung and saw-dust comprising a total weight of 150 kg and composted using rotary drum composter for 20 days in batch mode. The study outcomes indicated that the amendment of biochar prolonged the duration of the thermophilic temperatures, reduced salinity, and promoted nutritional quality of compost. Moreover, biochar amendment enhanced the organic matter degradation with a rate constant of 0.029 day−1 and increased the total Kjeldahl nitrogen content up to 1.75% from an initial value of 1.10% in the reactor with 2.5% biochar amendment. Concurrently, biochar amendment aided in reducing Cu and Cr in the final product inferring 2.5% biochar is best suited for composting of water hyacinth. However, future studies are encouraged to decipher the microbial shifts and bioavailability of metals due to biochar dosage during composting for mitigating and managing the menace of such fibrous waste like water hyacinth by converting it to a soil conditioner.
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24574. 题目: Potential application of chicken manure biochar towards toxic phenol and 2,4-dinitrophenol in wastewaters
文章编号: N19091801
期刊: Journal of Environmental Management
作者: Phan Quang Thang, Kim Jitae, Bach Long Giang, N.M. Viet, Pham Thi Huong
更新时间: 2019-09-18
摘要: In this study, chicken manure biochar (CBC) was prepared and applied as adsorbent for the removal of phenolic pollutants including phenol (Ph) and 2,4-Dinitrophenol (DNP) from wastewaters. The feasibility analysis was focused on the adsorption effects of various factors, such as initial concentration, adsorbent dosage and reaction time. The results showed that BC could efficiently remove the Ph and DNP within 90 min of reaction time. Increasing of CBC dosage up to 0.3 g results in the maximum removal efficiency of Ph and DNP and lowers initial concentration which is beneficial for the adsorption of phenolic compounds. The second-order kinetic model and the Langmuir isotherm provided the best correlation with the adsorption data. Based on the Langmuir isotherm, maximum adsorption capacities (qmax) of Ph and DNP were found at 106.2 and 148.1 mg g−1, respectively. The obtained qmax values for CB were higher than those reported in literature on the adsorption of Ph and DNP using different biochar. Analyzing the regeneration characteristics, BC displayed high reusability with less than 20% loss in adsorption capacities of Ph and DNP, even after five repeated cycles. Investigation of the adsorption equilibrium under various conditions suggested several possible interaction mechanisms, including hydrogen bonding, electrostatic interaction and π- π bonding, which were attributed to the binding affinity of the adsorbent-adsorbate interaction.In the field application, the CBC showed an excellent removal efficiencies of Ph and DNP from industrial wastewaters (around 80% phenolic pollutants were removed). These findings support the potential use of CBC as effective adsorbent for treatment of wastewater containing Ph and DNP.
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24575. 题目: Dynamics of dissolved greenhouse gas response to seasonal water mixing in subtropical reservoirs
文章编号: N19091712
期刊: Environmental Monitoring and Assessment
作者: Zhenglun Yang, Changyuan Tang, Xing Li, Han Zhang, Yangyang Cai
更新时间: 2019-09-17
摘要: Although indispensable, significant uncertainty still exists in the underlying processes of the formation, dynamics, and emission of greenhouse gases (GHGs), the critical elements needed for the accurate estimation of greenhouse gas fluxes in inland lakes and reservoirs. Seasonal changes in water thermal stratification and turbulence strongly influence the concentration and emission of dissolved GHGs in water columns. Here, we studied the stratification and overturn processes of water column in the subtropical Lianhe Reservoir during different seasons and determined the dynamics of dissolved CO2, CH4, and N2O in the reservoir. Observation of temperature and analysis of chlorofluorocarbons (CFCs) clearly suggested that stratification of water column occurred in summer, but not in winter. The results showed that while dissolved oxygen (DO) was high in the top 5-m layer (the upper epilimnion layer), it dropped considerably especially below 10 m, resulting in an increase in concentration of CO2 and CH4. The high concentrations of dissolved N2O and CH4 were related to the decomposition of organic matter in the hypolimnion layer under anaerobic conditions after stratification. In winter overturn period, vertical circulants of water not only homogenized the concentration of DO in the water column, but also potentially moved CO2, CH4, and N2O from the bottom to the surface of the reservoir. The estimated GHG flux from the reservoir was − 7.13 mmol m−2 day−1 in summer and 2.14 mmol m−2 day−1 in winter. There was the potential that CO2 fluxes from subtropical lakes and reservoirs are overestimated by traditional geochemical models.
24576. 题目: Functionalized Biochar/Clay Composites for Reducing the Bioavailable Fraction of Arsenic and Cadmium in River Sediment
文章编号: N19091711
期刊: Environmental Toxicology and Chemistry
作者: Xiaohua Wang, Yanling Gu, Xiaofei Tan, Yunguo Liu, Yahui Zhou, Xinjiang Hu, XiaoXi Cai, Weihua Xu, Chen Zhang, Shaoheng Liu
更新时间: 2019-09-17
摘要: Biochar has frequently been used for the treatment of heavy metal pollution in water and soil; its effect on contaminated sediments requires further research. To improve the ability of biochar to immobilize heavy metals in sediment, we prepared a functionalized biochar/attapulgite composite by pyrolysis of the clay attapulgite and zinc chloride–pretreated rice straw biomass. Compared with the original biochar, the biochar/attapulgite composite had a large increase in specific surface area, pore volume, oxygen‐containing functional groups, and cation exchange capacity. Biochar effectively improved the dispersibility of attapulgite as a matrix. The results showed that the biochar/attapulgite composite effectively reduced the bioavailable fraction of arsenic (As) and cadmium (Cd) in river sediment, which was a great improvement compared with the raw biochar. After the sediment was treated with different biochar/attapulgite composites, the concentrations of As and Cd in the overlying water and the porewater, and the content of acid‐extractable and toxicity characteristic leaching procedure (TCLP)‐extractable As and Cd in the solid phase of the sediment decreased significantly. Both zinc chloride activation and attapulgite improved As and Cd immobilization in sediment when we used the biochar/attapulgite composite. The results suggest that biochar/attapulgite composite can be used as an efficient in situ sorbent amendment to improve the heavy metal immobilization ability of the sediment. Environ Toxicol Chem 2019;00:1–11. © 2019 SETAC
24577. 题目: Molecular biomarkers reveal co-metabolism effect of organic detritus in eutrophic lacustrine sediments
文章编号: N19091710
期刊: Science of The Total Environment
作者: Jie Ma, Xiaoguang Xu, Cencen Yu, Huichao Liu, Guoxiang Wang, Zhichun Li, Bin Xu, Ruijie Shi
更新时间: 2019-09-17
摘要: In eutrophic lacustrine ecosystems, drifting algal blooms are easily trapped by emergent macrophytes in downwind littoral zones, potentially altering carbon cycling processes; yet, knowledge remains limited about the mechanisms driving these changes. In this study, Microcystis and Phragmites, two dominant photosynthetic organisms in a hypereutrophic (Lake Taihu, China), were collected to simulate their co-decomposition processes. We demonstrate how molecular-level biomarkers could be used to elucidate the degradation dynamics of these two distinct organic forms in mixtures. Microcystis-derived carbon accelerated the decomposition rate of mixed systems (positive co-metabolism effect), rather than retarding it. The decomposition rate of TOC (total organic carbon) directly measured in the mixed treatments was 14% higher than when the two substrates were incubated alone. The use of specific fatty acid biomarkers facilitated more accurate tracking, demonstrating 1.09 times higher decomposition rates for Phragmites detritus in mixed treatments than in single Phragmites treatments. Furthermore, Microcystis showed 0.98 times higher decomposition rates in mixed treatments than in single treatments. The addition of Microcystis detritus to Phragmites detritus might meet microbial stoichiometric requirements, increasing the abundance of decomposing bacteria in Phragmites detritus, and accelerating decomposition rates, resulting in the co-metabolism of Microcystis and Phragmites carbon. Given the increasing occurrence of algal blooms in eutrophic lakes, the processes documented here might enhance greenhouse gas emissions from lakes with continued global climate warming.
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24578. 题目: Impact of wildfires on subsurface volcanic environments: New insights into speleothem chemistry
文章编号: N19091709
期刊: Science of The Total Environment
作者: Ana Z. Miller, José M. De la Rosa, Nicasio T. Jiménez-Morillo, Manuel F.C. Pereira, José A. Gonzalez-Perez, Heike Knicker, Cesareo Saiz-Jimenez
更新时间: 2019-09-17
摘要: Siliceous speleothems frequently reported in volcanic caves have been traditionally interpreted as resulting from basalt weathering combined with the activity of microbial communities. A characteristic feature in lava tubes from Hawaii, Azores and Canary Islands is the occurrence of black jelly-like speleothems. Here we describe the formation process of siliceous black speleothems found in a lava tube from La Palma, Canary Islands, Spain, based on mineralogy, microscopy, light stable isotopes, analytical pyrolysis, NMR spectroscopy and chemometric analyses. The data indicate that the black speleothems are composed of a hydrated gel matrix of amorphous aluminum silicate materials containing charred vegetation and thermally degraded resins from pines or triterpenoids from Erica arborea, characteristic of the overlying laurel forest. This is the first observation of a connection between fire and speleothem chemistry from volcanic caves. We conclude that wildfires and organic matter from the surface area overlying caves may play an important role in the formation of speleothems found in La Palma and demonstrate that siliceous speleothems are potential archives for past fires.
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24579. 题目: A comprehensive comparison between non-bulking and bulking aerobic granular sludge in microbial communities
文章编号: N19091708
期刊: Bioresource Technology
作者: Qiulai He, Jing Zhang, Shuxian Gao, Li Chen, Wanlin Lyu, Wei Zhang, Jianyang Song, Xiaoling Hu, Rongfan Chen, Hongyu Wang, Jian Yu
更新时间: 2019-09-17
摘要: Filamentous sludge bulking poses great threats to operational stability of aerobic granular sludge. Exploration of the microbial community aids knowledge of the causative factors to sludge bulking and guides directions for corresponding actions for prevention and controlling. Detailed changes of bacterial community within the non-bulking and bulking were performed and compared with a non-specific method through 1‰ (v/v) hydrogen peroxide (H2O2) addition. Results revealed that non-bulking/bulking granules maintained effective carbon and nitrogen removal, while bulking completely deteriorated enhanced biological phosphorus removal (EBPR). Excess extracellular polymeric substances (EPS) especially polysaccharide (PS) were directly linked with sludge bulking and abundant PS contributed to subsequent granular re-stability. Filamentous bulking dramatically altered the bacterial populations and 1‰ H2O2 effectively controlled bulking by eliminating causative filaments Singulisphaera and Thiothrix. Together, this study provides new insights into the non-bulking/bulking granules and could direct the prevention and control of filamentous bulking in aerobic granules.
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24580. 题目: Effect of biochar addition to sewage sludge on cadmium, copper and lead speciation in sewage sludge-amended soil
文章编号: N19091707
期刊: Chemosphere
作者: Aleksandra Bogusz, Patryk Oleszczuk
更新时间: 2019-09-17
摘要: The goal of the present work was to evaluate the speciation of cadmium (Cd), copper (Cu) and lead (Pb) in sewage sludge (SL) amended soil and SL-biochar (BC) amended soil in a long-term field experiment. SL or SL with biochar (at the dose of 2.5%, 5.0% or 10%) were applied to the soil. The dose of SL in the soil was 11 tdw/ha. At the beginning of the study, after 12 and 18 months the distribution of Cd, Cu and Pb was determined between the following fractions: (1) water soluble, exchangeable and bound to carbonates (F1), (2) bound to Fe–Mn oxides (F2), (3) bound to organic matter (F3) and (4) bound to quartz, feldspars, etc. (F4). The soil, SL and biochar were characterized by different distribution of Pb, Cu and Cd. The highest mobility of Cd and Cu was observed in the control soil, while Pb in SL. Addition of SL to the soil caused the increased of the mobility index of Cu and Pb, increasing the risk associated with the presence of these metals in the mobile soil fraction (F1). However, the addition of biochar to SL before application to the soil modified the distribution of studied elements. The most mobile and bioavailable fractions (F1) were transferred to less bioavailable (F2, F3) and potentially immobile fractions (F4).
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