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精读 Reducing capacity of water extracts of biochars and their solubilization of soil Mn and Fe

精读 Reducing capacity of water extracts of biochars and their solubilization of soil Mn and Fe
精读 Reducing capacity of water extracts of biochars and their solubilization of soil Mn and Fe

European Journal of Soil Science,January2014,65,162–172doi:10.1111/ejss.12071 Reducing capacity of water extracts of biochars and their solubilization of soil Mn and Fe

E.R.G r a b e r a,L.T s e c h a n s k y a,B.L e w b&E.C o h e n a,c

a Institute of Soil,Water and Environmental Sciences,The Volcani Center,Agricultural Research Organization,POB6,Bet Dagan,50250, Israel,

b Institute of Agricultural Engineering,The Volcani Center,Agricultural Research Organization,POB6,Bet Dagan,50250,Israel, and

c Department of Soil an

d Water Sciences,Th

e Robert H.Smith Faculty o

f Agriculture,Food and Environment,Hebrew University of Jerusalem,Rehovot,76100,Israel

Summary

Biochar,being produced in an oxygen-restricted environment,is chemically more reduced than the original

feedstock.Consequently,it was hypothesized that reduced biochar components could participate in redox-

mediated reactions in the soil.This hypothesis was tested by measuring the reducing capacities of aqueous

extracts of biochars and the reduction and solubilization of soil Mn and Fe oxides by the extracts.The

reduction capacity of extracts from biochars produced from three feedstocks(eucalyptus wood,EUC;olive

pomace,OP;and greenhouse waste,GHW)at different highest pyrolysis treatment temperatures(HTT;350,

450,600and800?C)was less for the EUC feedstock than the others,and was greater for biochars produced at

lower HTTs.The organic fraction of the extracts apparently was responsible for the major part of the reducing

capacity.Extracts of smaller-HTT biochars,having greater dissolved organic carbon(DOC)contents,had

greater reducing capacities than extracts of larger-HTT biochars from the same feedstock.Extracts of two GHW

biochars(GHW-450and GHW-600)solubilized Mn and Fe from soils at pH values below8.The extract with

the greater reducing capacity(GHW-450)solubilized both metals to a signi?cantly greater extent.Smaller-HTT

biochars produced from agricultural wastes,having a greater variety and concentration of soluble reducing

agents,are expected to have more impact on soil redox reactions than larger-HTT biochars.By participating

in chemical and biological redox-mediated reactions in the soil,biochar could in?uence microbial electron

shuttling,nutrient cycling,pollutant degradation,contaminant mobilization and abiotic formation of humic

structures.

Introduction

Different types of biochar used along with organic and inorganic fertilizers can sometimes improve crop productivity(Lehmann et al.,2003),enhance soil aggregate structure(Liang et al., 2010),alter soil microbial populations(Kolton et al.,2011)and promote plant resistance to disease(Elad et al.,2010;Meller Harel et al.,2012).Some types of biochars have been suggested as contributing to plant growth directly as a result of their nutrient content and nutrient release characteristics(Silber et al.,2010). Biochars also have been thought to impact plant growth indirectly by increasing nutrient retention in the soil(Lehmann et al.,2003), improving soil pH(Yuan&Xu,2011),raising soil cation exchange capacity(Silber et al.,2010),improving soil water retention characteristics(Laird et al.,2010)and promoting bene?cial soil

Correspondence:E.R.Graber.E-mail:ergraber@https://www.wendangku.net/doc/a04976415.html,.il Received30May2013;revised version accepted30May2013microbes(Graber et al.,2010).It was also speculated that biochar-borne organic compounds could promote plant growth and health directly via chemical hormesis,or indirectly via their impact on the soil microbial community(Graber et al., 2010).However,the controlling mechanisms responsible for these various effects remain largely unknown.

Biochar is produced in an oxygen-restricted environment,and its polycondensed aromatic carbon structure and other components (mineral phases and organic molecules that are not integral parts of the condensed carbon framework)are in relatively reduced states compared with their states in the initial feedstock. We hypothesized therefore,that biochar could take part in a wide range of chemical and biological redox-mediated reactions in the soil and,in this way,in?uence important processes along the soil–microbe–plant continuum.These processes include microbial electron shuttling,nutrient cycling,root uptake of nutrients,free radical scavenging,abiotic formation of humic structures,pollutant degradation and contaminant mobilization or

162?2013British Society of Soil Science

Metal reduction and solubilization by biochar extracts163

immobilization(Bartlett&James,1993).Losses of chromium as Cr(VI)from suspensions of arti?cially contaminated soils and decreased chromate-induced toxicity in sun?owers have been attributed to biochar involvement in redox processes(Choppala et al.,2012).Promotion by biochar of reductive transformations of dinitro-herbicides and nitro explosives in the presence of a reducing agent has also been observed(Oh et al.,2013).

The water-soluble fraction of many biochars consists of a variety of soluble salts,colloidal minerals,small organic molecules belonging to various chemical classes and large macromolecular organic compounds similar in character to humic substances.A number of the small and large organic constituents making up the water-soluble fraction of biochar(Graber et al., 2010;Lin et al.,2011)are the same as or similar to those identi?ed in natural dissolved organic matter(DOM)as being redox-active (Fimmen et al.,2007).Such species(bearing quinoid,aromatic and thiol moieties)are important intermediaries in microbial metabolic processes and facilitate biological cycling of metals with multiple oxidation states(Lovley et al.,1998).As a consequence, they in?uence both microbial ecology and function(Visser, 1985).Dissolved OM components having multiple oxidation state heteroatom-containing structures(N or S)or inner-sphere metal-organic charge transfer complexes can also participate in abiotic electron transfer processes(Fimmen et al.,2007). Phenolic compounds with hydroxyl groups in the ortho-and para-position can chemically reduce manganese(Mn)and iron(Fe) oxides under normal soil conditions(Pohlman&McColl,1989), while carboxylate moieties accelerate chemical oxidation,thus encouraging redox cycling.Moreover,some biochar-borne organic compounds are ligands possessing multiple carboxyl,phenol, alcohol or enol groups(Graber et al.,2010;Lin et al.,2011), known to form stable metal–organic complexes with metals having different oxidation states.Formation of water-soluble metal–organic complexes can increase the concentration of metals in the aqueous phase and their bioavailability,while formation of water-insoluble metal–organic complexes can increase the soil organic matter content.

The goal of this study was therefore to evaluate the possibility that aqueous extracts of various biochars have signi?cant redox activity and may solubilize Mn and Fe from soils.

Materials and methods

Biochars

Biochars were produced from three feedstocks:(i)greenhouse wastes(GHW)consisting of pepper plant residues,(ii)olive pomace(OP)residues from olive oil production and(iii) eucalyptus(EUC)wood chips.The biochars were prepared in-house at different highest treatment temperatures(HTT;all feedstocks at350,450and600?C,and EUC additionally at800?C) in a slow pyrolysis reactor(BEK,All Power Labs,San Francisco, California,USA)operated in indirect retort mode.The biochars are designated according to the abbreviation used for the feedstock and the HTT:e.g.,GHW-350was produced from greenhouse waste at an HTT of350?C.Biochars were ground and sieved to a powder of<0.5mm particles and stored in sealed containers. Ash content(six replicates)was determined by mass loss of oven-dry(105?C)biochars after heating to500?C in air for12hours, followed by cooling to ambient conditions.Sample residue after loss on ignition was digested to dryness in concentrated HNO3at150?C,digested a second time in1:4concentrated HNO3:concentrated H2O2,dissolved in HNO3,and analysed for elements by inductively coupled plasma(ICP-AES;ARCOS SOP, Spectro Analytical Instruments,Inc.,Mahwah,New Jersey,USA) (Enders&Lehmann,2012).Biochar elemental analysis(C,H, and N)was determined in triplicate by an EA-1112Elemental Analyzer(Thermo Finnigan,Cambridge,Massachusetts,USA), with O being calculated by difference.Biochar speci?c surface area(SSA)was determined following degassing at120?C for 5hours by N2-BET adsorption using a Quantachrome Monosorb II instrument(The Israel Ceramic and Silicate Institute,Technion City,Haifa,Israel).Biochar characteristics(HTT,SSA,CHNO, elemental ratios,ash content and ash composition)are given in the Supporting Information(Table S1).

Aqueous extracts of the ten biochars were prepared in triplicate by shaking2.5g biochar with50ml deionized water(hereafter, water)in50ml polypropylene centrifuge tubes without headspace in the dark for24hours,followed by sedimentation and?ltration of the liquid solution via membrane?lters of0.22-μm pore size(Durapore PVDF membrane,Millipore Corp.,Carrigtwohill, Ireland).Extracts were characterized for dissolved organic carbon (DOC;TOC-V CPN,Shimadzu Corp.,Kyoto,Japan),redox potential(ORP probe),pH,electrical conductivity(EC),total phenols and reducing capacity.Other than preparing the extracts in sealed tubes in the absence of headspace,no attempt was made to control the atmosphere in contact with the extracts or to exclude oxygen.Reported reduction capacities do not represent the potential capacity of fully reduced species but rather, native reducing capacities.Pertinent chemical characteristics of the extracts are given in Table1.

Additionally,larger volumes of aqueous extracts of two biochars(GHW-450and GHW-600)were prepared for use in the experiments involving metal solubilization from soil.This was done by pre-wetting100g of biochar with approximately 60ml water,which was then placed in the centre of a large pre-wetted square of Whatman#1?lter paper.The?lter paper was gathered around the wetted biochar and tied with cotton string to make a‘biochar bag’.The biochar bag was suspended in one litre of water stirred by magnetic stirrer for24hours.The bag was periodically kneaded gently to ensure contact of the water with the biochar in the bag.After24hours,the aqueous solution was successively vacuum-?ltered through increasingly ?ner?lter papers and membranes,with the?nal?lter pore size being0.22μm(Durapore PVDF membrane,Millipore Corp., Carrigtwohill,Ireland).These solutions were characterized as before,and additionally by gas chromatograph/mass spectrometer (GC/MS)for organic species,and by ICP-AES or AAS for elements(details below).

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164 E.R.Graber et al.

Table1Pertinent chemical characteristics of biochar aqueous extracts

Biochar DOC a/mg l?1Redox potential b(E h)

/mV pH EC/mS cm?1

Total phenols

/μmol GAE l?1

Total phenols

/μmol GAE mg DOC?1

EUC c-35074119 6.90.8117.50.236

EUC-45044908.8 1.018.20.186

EUC-600281329.70.77

EUC-80024?1710.6 1.15

OP e-350371239.4 3.221260.338

OP-450404279.7 3.941490.368

OP-600853210.1 5.8610.80.127

GHW f-350248139.97.311330.537

GHW-45042759.78.512040.478

GHW-60042?2910.77.71 6.20.148

SRNOM520n.a.n.a.n.a.4340.835

SRFA520n.a.n.a.n.a.610 1.17

PPHA520n.a.n.a.n.a.4140.796

PPFA520n.a.n.a.n.a.2170.417

Water2443 4.70.001

a DOC,dissolved organic carbon.Reproducibility of DOC analysis is better than7%.

b Redox potential(E h)–reproducibility is better than10%.

c EUC,biochar made from eucalyptus woo

d chips at highest treatment temperature(HTT)in?C as speci?ed by number following EUC-.

d MDL,method detection limit.Th

e MDL for total phenols is3μmol GAE l?1,and the reproducibility(three replicate analyses)for a given sample is better than5%.

e OP,biochar made from olive pomace at highest treatment temperature(HTT)in?C as speci?ed by number following OP-.

f GHW,biochar made from greenhouse waste at highest treatment temperature(HTT)in?C as speci?ed by number followin

g GHW-.

Notes:For biochar extracts,properties were measured in1:20mass:volume biochar:deionized water mixed for24hours and?ltered with a0.22-μm?lter. EC,electrical conductivity;GAE,gallic acid equivalents;n.a.,not applicable;PPFA,Pahokee Peat Fulvic Acid;PPHA,Pahokee Peat Humic Acid;SRFA, Suwannee River Fulvic Acid;SRNOM,Suwannee River Natural Organic Matter.

Natural dissolved organic matter(DOM)standards

For purposes of comparing the reducing capacities of biochar aqueous extracts to those of natural dissolved organic matter (DOM)solutions,four DOM standards from the International Humic Substances Society(IHSS;Saint Paul,Minnesota,USA) were used:Suwannee River Natural Organic Matter(SRNOM;cat. #IN101),Suwannee River Fulvic Acid(SRFA;cat.#1R101F), Pahokee Peat Humic Acid(PPHA;cat.#1S103H),and Pahokee Peat Fulvic Acid(PPFA;cat.#2S103F).Stock aqueous solutions (1mg DOM ml?1)were made up in water and diluted as needed. PPHA was dissolved in1m m NaOH(pH9)and then neutralized with100m m HCl.

Soils

Four soils of differing textures,representing major soil types in Israel,were collected from the cultivated layer(0–25cm)and used in this study:(i)sand(Typic Xerochrept)from Bet Dagan, the Coastal Plain;(ii)light clay(Chromic Haploxeralf),from Hefetz Haim,in the Pleshet Plains;(iii)clayey loam(Calcic Haploxeralf),from Nahal Oz,in the Northern Negev;and(iv) heavy clay(Chromic Haploxeralf),from Eilon,in the Western Galilee(the soil classi?cation is that of Soil Survey Staff,1999). The soils were air-dried,crushed,sieved(<1mm),and stored in closed containers under ambient laboratory conditions.Soil texture was determined by the hydrometer method(Bouyoucos,1962) according to the international classi?cation system,taxonomy was speci?ed according to the United States Department of Agriculture(USDA)soil taxonomic system,soil organic matter (SOM)was determined by the Walkley-Black method(Walkley, 1947),pH was determined in the supernatant of a1:10w:v soil:water slurry mixed for24hours,and cation exchange capacity (CEC)and%CaCO3following standard methods(Nelson,1982; Rhoades,1982).Selected soil data are tabulated in the Supporting Information,Table S2.

Total phenols and reducing capacity

Total phenols in the biochar aqueous extracts and DOM solutions were determined with the Folin-Ciocalteu(FC)assay(Singleton et al.,1999).The FC reaction involves oxidation of phenols and other compounds(Singleton et al.,1999)by a phosphomolybdic tungstic acid reagent in a basic medium(pH10),resulting in the formation of superoxide ion.The superoxide ion reacts with molybdate to form molybdenum oxide(MoO4+)which has a very intense absorbance at725nm.The FC reaction mechanism is thought to involve single electron transfer according to the reduction half-reaction Mo(VI)+e→Mo(V).The FC assay, conducted at pH10,has fast reaction kinetics for phenolic species because the kinetics of phenol electron donating,via the phenolate anion,is strongly favoured at the high pH(Singleton et al.,1999).

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Metal reduction and solubilization by biochar extracts165

Following convention for reporting total phenols by the FC assay, gallic acid was used to develop a standard curve,and total phenol results are reported in gallic acid equivalents(GAE)asμmol GAE ml?1extract.FeSO4·H2O standards were also measured by the FC assay to calculate reducing capacity in terms of moles of charge transfer(mol c),where each mole of FeSO4represents one mole of charge transfer.

The ferric reducing antioxidant power(FRAP)assay(Benzie& Strain,1996)was also used to determine reducing capacity.The FRAP assay measures the reduction of the ferric tripyridyltriazine complex,Fe(III)-TPTZ,to the ferrous Fe(II)-TPTZ complex at pH 3.6,according to the reduction half-reaction Fe(III)+e→Fe(II). Fe(II)-TPTZ has an intense blue colour and is monitored by absorption at a wavelength of593nm and quanti?ed using FeSO4·H2O standard solutions.The FRAP assay is conventionally determined after only4minutes reaction time,as it was developed with compounds which exhibited very fast reaction kinetics. However,the reaction kinetics for many phenols and polyphenols can be slow because the kinetics of phenol electron donating is sluggish at the low pH of the assay(Singleton et al.,1999). Therefore,we followed the FRAP reaction for samples and standards for240minutes.Over this time,there was no signi?cant change in the absorption of the standards.As with the FC assay,the FRAP assay mechanism is nonspeci?c single electron transfer,but the two assays have different standard reduction potentials(E h=+0.43V and+0.70V for the reduction half-reactions involved in the FC and FRAP assays,respectively, (https://www.wendangku.net/doc/a04976415.html,/physics/redpot.htm)).Standard reduction potentials of several humic acid samples were reported to range between+0.15and?0.30V(Aeschbacher et al.,2011).

Gas chromatograph/mass spectrometer(GC/MS)analysis

of extracts

Aliquots(2ml)of the GHW-450and GHW-600extracts used for the solubilization experiments were lyophilized and the dried residue subjected to a two-stage derivatization procedure immediately prior to analysis by GC/MS.The residue was?rst derivatized for2hours at37?C using40μl of methoxyamine in pyridine(20mg ml?1)to stabilize carbonyl moieties.Following methoxyamination,functional groups such as-OH,-COOH,-SH and-NH groups were converted into trimethylsilyl(TMS)-ethers, TMS-esters,TMS-sul?des or TMS-amines,respectively,using 70μl of N-methyl-N-(trimethylsilyl)tri?uoroacetamide(MSTFA) by heating for30minutes at37?C.Following derivatization, the samples were diluted with125μl pyridine and?ltered by Te?on membrane syringe?lter(0.45μm)to remove solids (inorganic salts in the aqueous extracts).The derivatized extracts were analysed by quadrupole GC/MS(Agilent Technologies, Santa Clara,California,USA)using electron impact ionization. Separation was achieved on a30-m long,VF-5M,0.25μm?lm, capillary column(Varian Inc.,Palo Alto,California,USA)using the following conditions:initial oven temperature60?C,initial hold15minutes,ramp5?C minute?1to a?nal temperature of 330?C,?nal hold5minutes,MS source230?C,injector230?C; MS Quad150?C;m/z range50–600.

Total ion chromatograms(TIC)were analysed with freely available deconvolution software(Automated Mass Spectral Deconvolution and Identi?cation System(AMDIS),developed by the National Institute of Standards&Technology(NIST))at a minimum match probability of75%and retention indices based on a series of alkanes.The deconvoluted mass spectra were compared with a specialty library for plant,animal and microorganism metabolites(Golm Metabolite Database)freely provided by the Max Planck Institute for Metabolic Plant Physiology(Golm, Germany)and with the NIST08mass spectral library.

Mn and Fe solubilization from soil

Solubilization of Mn and Fe from the sandy soil,and Mn from the other three soils,was compared for two biochar aqueous extracts(GHW-450and GHW-600)and water as a function of pH,which was modi?ed with buffers as detailed below.Soil (2g)was weighed into50-ml disposable polypropylene centrifuge tubes equipped with screw caps.Buffer(10ml)and aqueous biochar extracts or water(10ml)were added to the tubes,and the suspensions(or soilless controls)were shaken in the dark for 24hours on a horizontal table shaker at120cycles minute?1.Each point(samples and controls)was made in triplicate;average values and bars denoting standard error are given in the Figures.No attempt to exclude oxygen or otherwise control the atmosphere in the tubes other than hermetical capping was made.After24hours, the tubes were centrifuged(12000×g)for15minutes,and the supernatant?ltered through0.22-μm syringe?lters(Durapore PVDF membrane,Millipore Corp.,Carrigtwohill,Ireland)).The ?ltered solutions were analysed by inductively coupled plasma-atomic emission spectroscopy(ICP-AES;ARCOS SOP,Spectro Analytical Instruments,Inc.,Mahwah,New Jersey,USA:sandy soil)or by atomic absorption spectroscopy(AAS;Analyst800 atomic absorption spectrophotometer,Perkin Elmer,Waltham, Massachusetts,USA:all other soils).Manganese and Fe release was calculated as the difference between the total concentration measured in the soil-containing samples(extract or water+buffer +soil)and the soilless controls(extract or water+buffer), and is denoted in the?gures with a notation.Since Zn(III) is hardly amenable to reduction,yet is more readily complexed by most organic ligands than Mn(Furia,1980),Zn concentrations were also determined to help differentiate between reduction and complexation mechanisms potentially involved in solubilization. Preliminary experimentation showed that release of the metals from soil was not affected by total salt concentrations in the ranges found in the aqueous biochar extracts.Moreover,DOC release and sorption by the soils were negligible.

Buffers(100m m)were made up using the following solutions: (A)glacial acetic acid(8.6ml made up to1.5l in water;(B) sodium acetate trihydrate(27.2g)made up to2l in water;(C) disodium hydrogen phosphate(28.4g)made up to2l in water; and(D)0.1m HCl.Buffer pH4was made by mixing153ml(A)

?2013British Society of Soil Science,European Journal of Soil Science,65,162–172

166 E.R.Graber et al.

and847ml(B);pH5by mixing643ml(A)and357ml(B);pH6 by mixing947.8ml(A)and52.2ml(B);pH7by mixing756ml

(C)and244ml(D);pH8by mixing955.5ml(C)and44.9ml

(D).Despite the use of buffer solutions,it was dif?cult to achieve target pH values because of the strong buffering capacities of the soils and extracts.Therefore,results were compared within buffer systems by using the actual measured pH values at the time of sampling.

Statistics

GraphPad Software,Inc.(San Diego,California)was used for carrying out unpaired two-tailed Student’s t-tests.Results reported as signi?cant were at P<0.01.

Results

Chemical characteristics and reducing capacity of biochar extracts and DOMs

Extracts of OP and GHW biochars were alkaline and relatively saline(Table1)regardless of pyrolysis HTT.Extracts of the GHW biochars in particular had elevated salt contents,because the feedstock comprised residues of pepper plants grown on saline water(3–4.5dS m?1).The pH of EUC biochar extracts increased from neutral to alkaline as a function of increasing pyrolysis HTT. For a given feedstock,extracts of smaller-HTT biochars(350and 450?C)had notably larger DOC concentrations than extracts of larger-HTT biochars(Table1).At the smaller-HTTs,feedstock had a particularly strong impact on DOC content,with biochars from the agricultural residues(GHW and OP)having extracts with signi?cantly higher DOC concentrations than those produced from wood;the differences between feedstocks decreased for biochars produced at600?C.All the biochar extracts had redox potentials(as measured by ORP probe)signi?cantly less than that of water(Table1).The concentrations of metals in the GHW-450and GHW-600extracts that were used for the solubilization experiments were very small(Table2).

The biochar extracts exhibited large differences in concentration of total phenols(from not detectable to204μmol GAE l?1), with extracts of smaller-HTT biochars having much greater concentrations than extracts of larger-HTT biochars(Table1). While the major part of the difference was mainly related to DOC content of the extracts(linear regression of total phenols (TPs)against DOC:TP=0.4416DOC?10.77;R2=0.943), normalization to unit weight of DOC shows that extracts of smaller-HTT biochars had greater content of total phenols per unit of DOC(Table1).On a unit DOC weight basis,total phenol contents of smaller-HTT biochar extracts were of the same order as those of natural DOM samples(Table1).

Reducing capacity was calculated from both the FC assay(using the Fe2SO4standard curve)and the FRAP assay(Figure1).For all the biochar extracts except that of GHW-600,the FRAP4reducing capacity was signi?cantly less than that determined by the FC assay(Figure1).Over the4–240minute FRAP assay time,the Table2Elemental content of aqueous extracts of biochars GHW-450and GHW-600used in solubilization experiment determined by inductively coupled plasma-atomic emission spectroscopy(ICP-AES).ICP-AES analysis was performed in triplicate;differences between replicates were less than5%

Element GHW-450/μmol ml?1GHW-600/μmol ml?1

Al0.00930.0006

B0.05450.0456

Ba0.00020.0000

Ca0.19710.0863

Cr0.00010.0000

Cu0.00060.0000

Fe0.00390.0004

Li0.03040.0177

Mg 1.69100.0235

Mn0.00010.0000

Mo0.00010.0002

Na 5.2634 6.4814

Ni0.00010.0000

P0.01970.0251

S 4.1166 4.8339

Si0.15600.1720

Sr0.00430.0009

Ti0.00140.0000

Zn0.00080.0000

reducing capacity increased for all the biochar extracts(Figure1). For the most part,the reducing capacity at FRAP240was less than, or nearly the same as,that of the FC assay(Figure1).However, several extracts,notably those of GHW-600,EUC-350and EUC-450,had signi?cantly larger FRAP240reducing capacities than FC reducing capacities(Figure1).

The increase in FRAP reducing capacity from4(FRAP4) to240minutes(FRAP240)was generally larger for the biochar extracts than the natural DOM samples(Figure1).Between FRAP4and FRAP240,the reducing capacity of the DOM samples increased by1.2(PPHA)to3.4(SRNOM)times,while that of the biochar extracts increased by3.0(OP-600)to6.1(GHW-600)times.In contrast to the biochar extracts,FRAP240reducing capacities of the DOM samples were always much smaller than their respective FC reducing capacities.

A number of compound classes were identi?ed putatively by GC/MS in the aqueous extracts of GHW-450and GHW-600 biochars:polyols,hydroxy acids,benzoic acids,substituted heterocyclic amines,urea,medium and long-chain alkanoic carboxylic acids,dicarboxylic acids,sugars,sugar alcohols,sugar acids,anhydrosugars and glycerol-substituted long-chain acids (Table3).Some of the compounds have structures associated with redox activity,in particular the aromatic compounds and heterocyclic amines.Other identi?ed compounds,mainly the dicarboxylic acids,have considerable propensity to form stable complexes with metals.Twice as many compounds overall were identi?ed in the extract of GHW-450as in the extract of GHW-600(35compared with17).It should be noted that

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Metal reduction and solubilization by biochar extracts 167

E U

C

-3

50

E U

C

-4

50

E U

C

-6

00

E U

C

-8

00

O

P -3

50

O

P -

45

O

P -600G H W -350G H W -450G H W -600S R N O M

S R

F A

P P H

A

P P F A

12345678R e d u c i n g C a p a c i t y /μm o l c m g D O C

-1

Figure 1Reducing capacity in μmol c per unit dissolved organic carbon (mg DOC)of the biochar extracts and natural dissolved organic matter (DOM)samples measured by the Folin-Ciocalteu (FC)assay and the FRAP (Ferric Reducing Antioxidant Power)assay.The number following the FRAP designation represents the time in minutes from the start of the reaction;thus,FRAP4is the reading taken 4minutes after the start of the reaction.Abbreviations for biochars and DOM samples are as given in the text.Error bars represent the maximum propagated standard error (7%of the mean value).

the major portion of organic carbon in the extracts was not identi?able by GC/MS,thus the compounds in Table 3represent only a small fraction of the total carbon present.

Mn and Fe solubilization from soils

Extracts of GHW-450and GHW-600solubilized more Mn and Fe from the sandy soil than did the control solutions at neutral to acidic pH values,with the amount of metal released into solution increasing with decreasing pH (Figure 2).The relative solubi-lization power of the extracts compared with the control solution also increased as pH decreased (Figure 2).The same trend was observed for Mn solubilization in the other three soils (Figure 3).At a given pH,the extract of the small-HTT biochar (GHW-450)solubilized signi?cantly more Mn and Fe than did the extract of the large-HTT biochar (GHW-600;Figures 2,3);for example,at pH 5.1,releasing 3.7times more Mn and 12.7times more Fe from the sandy soil (respectively,Mn,146±8.4and 39.8±0.15μmol l ?1;and Fe,5.0±0.57and 0.4±0.01μmol l ?1;Figure 1).The extent of Mn solubilization differed from soil to soil (Figures 2,3),re?ecting the particular chemistry of each soil in contact with the extracts,but in all cases,the GHW-450extract released signi?cantly more Mn than the GHW-600extract.In general in the different soils,enhanced solubilization by the biochar extracts disappeared at pH greater than 7.5–8.

No difference in Zn release in biochar extracts or control solutions was observed in any of the soil-pH systems (not shown).

Discussion

As phenols have fast redox reaction kinetics in the FC assay and slow reaction kinetics in the FRAP assay,the signi?cantly larger reducing capacity measured by the FC assay than that measured at 4minutes in the FRAP assay (FRAP4),suggests that phenolic compounds were responsible for the greater part of the reducing capacities of the extracts.Phenols are among the compounds responsible for the redox activity of natural DOMs (Rimmer &Abbott,2011;Aeschbacher et al.,2012).In general,the measured reducing capacities of the DOM and biochar samples were in the range of the electron donating capacities determined for 15different humic substances over a large range of pH and E h values measured using mediated electrochemical oxidation (Aeschbacher et al.,2012).For some extracts,the long-time FRAP reducing capacity (FRAP240)exceeded that of the FC assay,perhaps indicating that those extracts contained additional species whose oxidation half-reaction potentials were suf?cient for reducing Fe(III)in the FRAP assay,but not Mo(VI)in the FC assay.

The natural DOM samples had notably slower FRAP kinetics than the biochar extracts.DOM is known to have sluggish redox kinetics (Aeschbacher et al.,2010)and possibly slow dissociation kinetics because of the time needed for diffusion into the macromolecular framework.Biochar extracts contain both low and high molecular weight organic compounds (Graber et al.,2010;Lin et al.,2011),such that their kinetics and chemical processes may differ from those that characterize natural DOM.

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168 E.R.Graber et al.

Table3Putative identi?cations by gas chromatograph/mass spectrometer(GC/MS)of compounds in aqueous extracts of greenhouse waste(GHW)biochars produced at450?C(GHW-450)and600?C(GHW-600)

Compound Class GHW-450GHW-600

Lactic acid Hydroxy acid Y a Y Hexanoic acid n-Alkanoic acid Y

Hydroxy-acetic acid Hydroxy acid Y Y Ethandioic acid Dicarboxylic acid–Y

4-Hydroxy-butyric acid Hydroxy acid Y–Benzoic acid Benzoic acid Y Y

Urea Urea Y–Octanoic acid n-Alkanoic acid Y–Glycerol Polyol Y Y Succinic acid Dicarboxylic acid Y Y

2-Methyl benzoic acid Substituted benzoic acid Y–

2-Methyl butanedioic acid Dicarboxylic acid Y Y Glyceric acid Hydroxy acid Y Y Nonanoic acid n-Alkanoic acid Y–Glutaric acid Dicarboxylic acid Y–

2,4-Bis[hydroxy]butanoic acid Hydroxyl acid Y–Benzenepropanoic acid Aromatic organic acid Y–Decanoic acid n-Alkanoic acid Y–Butane-1,2,3,4-tetraol(erythritol)Polyol Y–Pentane-1,2,5-triol Polyol Y–

5-Oxo-pyrrolidine-2-carboxylic acid(pyroglutamic acid)Substituted heterocyclic amine Y Y Piperidine-2-carboxylic acid Substituted heterocyclic amine–Y

2-Hydroxy-pentandioic acid Dicarboxylic acid Y–Erythronic acid Sugar acid–Y Threonic acid Sugar acid–Y

3-Hydroxy-benzoic acid Substituted benzoic acid Y–

1H-benzoimidazole,1-(2-ethoxyethyl)-2-(4-methoxyphenyl)Substituted imidazole Y–

2,4,5-Trihydroxypentanoic acid Hydroxy acid Y–Ethane-1,2-diol(ethylene glycol)Diol Y–

1,6-Anhydroglucose Anhydrosugar Y–Ribitol Reducing sugar Y–Mannitol Sugar alcohol Y Y Hexadecanoic acid n-Alkanoic acid Y Y

Myo-inositol Polyol Y Y Octadecanoic acid n-Alkanoic acid Y Y

1-Monohexadecanoylglycerol Glycerol ester Y–

2,3-Bis[(hydroxyl)propyl]-hexadecanoic acid Carboxylic acid Y–Melezitose Trisaccharide–Y Trehalose Disaccharide Y–Monooctadecanoylglycerol Ketoglycerol Y–

a Y-identi?ed in the extract.

The GC/MS analysis revealed redox-active small molecules in the biochar extracts,but large molecules are not amenable to GC/MS analysis,nor are small polar compounds that lack groups having active H atoms.Many large polyphenols,tannins and other macromolecular species such as humic-like substances produced during the pyrolysis process(Lin et al.,2011)cannot be detected by GC/MS,yet are expected to play a role in the redox activity of the extracts.They may also form complexes with metals. Most of the metals naturally present in the extracts are assumed to be complexed with organic species or present as mineral nanoparticles.In general,the redox reaction rate of metal species is fast,particularly at the low pH conditions of the FRAP assay.Therefore,it is expected that the original metal content of the extracts does not play the major role in their redox activity,in accordance with previous?ndings for metals in DOM solutions (Aeschbacher et al.,2011).

While formation of complexes between soil metals and organic ligands in the extracts potentially may be a mechanism for the observed enhanced solubilization of Mn and Fe by the biochar extracts,this possibility is not supported by the results of the Zn

?2013British Society of Soil Science,European Journal of Soil Science,65,162–172

Metal reduction and solubilization by biochar extracts 169

0306090120150

180

Sand

010********Solution pH

Δ E l e m e n t C o n c e n t r a t i o n / μm o l l -1

Figure 2Release of Mn (a,b)and Fe (c,d)from a sandy soil into the extract of greenhouse waste (GHW)biochar produced at a highest treatment temperature (HTT)of 450?C (GHW-450)and 600?C (GHW-600),and water as a function of pH.Error bars represent standard errors,and when not present are smaller than the symbols.

analyses.Zinc(III)is poorly amenable to reduction,yet is more readily complexed by most organic ligands than Mn (Furia,1980).As there was no difference in Zn released to the extracts or con-trols,it is suggestive that the cause of Mn (and Fe)enhanced sol-ubilization was indeed reduction and not complexation by organic ligands.Manganese release was greater than that of Fe,presum-ably because the reduction potentials of most soil Mn oxides are greater than those of most soil Fe species (Bartlett &James,1993).Biochar feedstocks differ in chemical composition,and cor-respondingly,chemical properties of biochar differ as a func-tion of feedstock.The disparities in reducing capacity among the biochars from various feedstocks in this study are thought to re?ect these chemical differences.Extracts of smaller-HTT biochars had greater reduction capacities than those of larger-HTT biochars,implying that biochars produced at smaller HTTs have greater potential for participating in redox reactions in soil.Notably,when the soil mineral solubilization results were normal-ized to the DOC content of the extracts,the larger-HTT biochar extract had signi?cantly greater solubilization power than the smaller-HTT biochar extract (shown for Mn for all four soils in Figure 4).This result corresponds to the signi?cantly greater DOC-normalized FRAP240reducing capacity of the extract from the larger-HTT biochar (GHW-600)compared with the extract of the smaller-HTT biochar (GHW-450),and demonstrates how HTT can affect the nature of the redox active compounds in biochar.

The implications of these results for the role of biochar in the soil may be far-reaching.Because oxidation of biochar solids leads to continued release of redox-active,acidic and phenolic organics of both low and high molecular weight (Abiven et al.,2011),biochar may continue to participate in redox reactions as

it ages in the soil.This could have consequences for soil release of nutrient or contaminant metals,and their bioavailability or mobility in the environment.

As well as the importance of oxidation state for the value of Fe and Mn as micronutrients,their oxidation state can affect the oxidation states of other metallic species such as chromium (Tokunaga et al.,2007).Reduced Fe and Mn species have been suggested as catalysts for abiotic reduction of nitrate to nitrite,with nitrite reacting with dissolved organic compounds via nitration and nitrosation of aromatic ring structures to produce organic N structures (Davidson et al.,2003).Such abiotic redox reactions could be one of the ways by which biochar in?uences soil N cycles and could contribute to the build-up of SOM.In a series of papers,Rimmer and colleagues (Rimmer,2006;Rimmer &Smith,2009;Rimmer &Abbott,2011)suggested that soil polyphenols scavenge free radicals,thus terminating the oxidative chain reactions responsible for SOM breakdown.Polyphenols released from biochars could perform similar functions,which may be one means by which biochar helps to stabilize soil organic matter.

Redox reactions between biochar organic compounds and soil metals could contribute in other ways to SOM stabilization.Phenolic compounds with hydroxyl groups in the ortho -and para -position are known to reduce Mn and Fe under normal soil conditions and precipitate as polymeric humic-like substances (Pohlman &McColl,1986,1989).This mechanism accords with observations that biochar added to soil resulted in enhanced breakdown of fresh organic material followed by its incorporation into soil aggregates and organo-mineral fractions,leading to stabilization of originally labile organic matter (Liang et al.,2010).

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170 E.R.Graber et al .

030

6090120150180GHW-450

GHW-600

030609012004080120160200Solution pH

Δ M n C o n c e n t r a t i o n / μm o l l -1

Figure 3Release of Mn into the extract of greenhouse waste (GHW)biochar produced at a highest treatment temperature (HTT)of 450?C (GHW-450)and 600?C (GHW-600),and water compared as a function of pH for three soils (light clay (a,b)GHW-450and GHW-600,respectively:clayey loam (c,d)GHW-450and GHW-600,respectively:heavy clay (e,f)GHW-450and GHW-600,respectively).Error bars represent standard errors,and when not present are smaller than the symbols.

The effect of biochar on soil microbial processes and communi-ties (Graber et al.,2010;Kolton et al.,2011)could also be related to redox activity of biochar,with components in the water-soluble fraction enabling electron transfers between bacterial cells and Fe(III)-bearing minerals.Redox active substances could take part in bacterial reduction and immobilization of contaminants such as Cr(VI)(Choppala et al.,2012)or,alternatively,cause the abiotic release of contaminants such as arsenic that are associated with Fe oxides.

The speci?c effect of biochar addition on release and solu-bilization of soil metals will depend not only on the reduction capacity and chelating potential of the water-soluble components of biochars,but also on prevailing pH conditions.While solu-bilization of soil metals by biochar extracts is enhanced when compared with water at a given pH,biochars and their extracts having basic pH values may raise soil pH in acidic sandy soils (Yuan &Xu,2011)and hence result in overall decreased metal release to soil solution.In this way,biochar could result in decreased metal toxicity and contamination risks in acidic sandy soils despite its content of reducing agents and organic ligands.

Conclusions

Water extracts of many biochars have substantially smaller redox potentials than water and can solubilize soil Mn and Fe.The dissolved organic matter fraction appears to be mainly responsible for the redox activity of the extracts examined in this study,although metals released from biochars prepared from other feedstocks or under different conditions may also be important.While some compounds making up the water-soluble fraction are also able to form complexes with released metals,in this study,reduction was apparently the main process responsible for Mn and Fe solubilization from soils.The implications of this are that many biochars have the possibility of participating in a variety of chemical and biological redox-mediated reactions in the soil.In this way,biochar could in?uence important processes occurring in the soil,such as microbial electron shuttling,nutrient cycling,free radical scavenging,pollutant degradation,contaminant mobilization,and abiotic formation of humic structures in soils.Participation in varied redox reactions may be among the many mechanisms involved in the impact of biochar on the soil environment.

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Metal reduction and solubilization by biochar extracts 171

4

8

4

8

12

Solution pH

Δ M n c o n c . / μm o l M n m m o l D O C -1

Figure 4Release of Mn per unit dissolved organic carbon (DOC)from four soils,(a)sand,(b)light clay,(c)clayey loam and (d)heavy clay,compared between extracts of greenhouse waste (GHW)biochar produced at a highest treatment temperature (HTT)of 450?C (GHW-450)and 600?C (GHW-600).Error bars represent standard errors,and when not present are smaller than the symbols.

Supporting Information

The following supporting information is available in the online version of this article:

Table S1.Physical and chemical characteristics of the biochars used in this study.

Table S2.Soil characteristics.

Acknowledgements

The authors would like to acknowledge Dr Stephen Joseph for many interesting conversations on the redox behaviour of biochars and other subjects,and Professor Uri Mingelgrin for helpful discussions on the nature of redox reactions.A critical review of an earlier version of the manuscript by Dr Michael Sanders was very insightful and important,and his contribution is gratefully acknowledged.Ms Racheli Rozenfeld assisted in various aspects of the laboratory experiments.Dr Guy Levy and Ms Dina Goldstein are thanked for providing three of the soils and analyses of their physical-chemical characteristics.This research was supported by public grants from the Chief Scientist of the Israel Ministry of Agriculture and Rural Development,projects 301-0693-10and 261-0848-11,and the Israel-Italy Program 2011(project 301-750-11).

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胜任素质词典 注:以下排列不分先后 代码表示含义: A-1:不合格的胜任特征行为 A-0:合格的胜任特征行为 A+1:优秀的胜任特征行为 A+2:卓越的胜任特征行为 1、全局观念(OVV) 【定义】从组织整体和长期的角度,进行考虑决策、开展工作,保证企业健康发展。 认清局势深刻理解组织的战略目标,组织中局部与整体、长期利益与短期利益的关系,以及其他各关键因素在实现组织战略中的作用。 尊重规则有较强的法律、制度意识,尊重企业运作中的各种规则,不会为局部小利而轻易打破规则和已经建立的平衡与秩序。 团结协作倡导部门间相互支援、默契配合,共同完成组织战略目标。 甘于奉献明确局部与整体的关系,在决策时能够通盘考虑;以企业发展大局为重,在必要时能够勇于牺牲局部“小我”和暂时利益,为企业战略实现和长远发展的大局让路。

2、信息分析(INF) 【定义】能够把那些原始的、零散的材料经过归纳整理,综合分析,去粗取精,去伪存真,变成系统的、具有较强操作性和指导性的意见、建议。 信息搜集能够通过网络、报章杂志书籍、会议和人际交流等多种途径,快速获得大量信息。 信息管理能够有意识地做好信息的分类、整理和贮存,以便在必要时可以迅速调用。 信息加工能够从零散的信息中,敏锐地洞察社会、行业以及市场等的新动向、新趋势,并判断分析出潜在的发展机会。 整合与应用能够将来源不同的信息整合起来,并将信息分析中呈现的新动向和新趋势与企业实际相联系,提出预见性建议,为规划企业发展以及应对市场变化提供依据。 3、战略思考(STG)

【定义】深刻理解公司战略思想,根据本企业实际将战略落到实处,并采取相应的措施保证战略的实现。 战略理解对组织战略制定的背景、原则和重点有透彻的理解,并向下属正确的传达与解释。 战略分析分析市场环境的机遇与挑战,组织的优势与劣势,探寻实现战略的机会,确定达到战略目标的实施策略。 战略实施结合组织现实的资源状况、运作模式和企业文化,制定与战略目标一致的具体行动计划,并在计划实施过程中不断校正计划与战略的偏差。 战略评估与反馈总结战略实施成功与失败的关键信息,评估战略价值,向上级提出建设性的意见或建议。 4、制度构建(PRP) 【定义】根据组织的战略规划和业务构成,搭建和优化符合企业实际的、系统化的管理与运作制度体系。 制度意识对企业管理制度的功能、作用机制与结构有全面的认识和深刻的理解,有通过建立规范的制度来提高组织运作效率的意识。 制度知识对国内外先进企业的管理制度有广泛的了解,探究各种管理制度的原理、作用及其优劣。 系统化在制定和修订制度时,能够将各种管理与运作制度进行有机整合,保证制度体系的完整性、系统性和一致性。 坚持原则有坚持按制度办事的决心和魄力;同时,使制度得到切实贯彻与执行, 而不是流于形式。 评估与优化根据执行情况对制度进行客观的评估,对有缺陷或因工作任务的变化而需要改进的制度,及时进行修改或重建。

托福阅读词汇分类技巧(一)

托福阅读词汇分类技巧(一)托福阅读词汇分类技巧(一) https://www.wendangku.net/doc/a04976415.html,/tuofuyuedu/20141219/329225.html?seo=wenku Example: OG Practice Set 4,question 10

Passage 8: One cognitive theory suggests that aggravating and painful events trigger unpleasant feelings. These feelings in turn,can lead to aggressive action,but not automatically. Cognitive factors intervene. People decide whether they will act aggressively or not on other people’s motives. Supporting evidence comes from research showing that aggressive people often distort other people’s motives. For example, they assume that other people mean them harm when they do not. The word distort in the passage is closest in meaning to ○ mistrust ○ misinterpret ○ criticize ○ resent 解析:distort所在的文章句子后出现“ for example”,根据for example 中的内容,我们可以得出distort在此句中的意思为misinterpret。 3. 并列信息 Example: OG Practice Set 5,question 3 Passage 3: …Absenteeism and lateness hurt productivity and since work was specialized,disrupted the regular factory routine. Industrialization not only produced a fundamental change in the way work was organized; it transformed the very nature of work. The word disrupted in the passage is closest in meaning to ○ prolonged 托福阅读词汇分类技巧(一) https://www.wendangku.net/doc/a04976415.html,/tuofuyuedu/20141219/329225.html?seo=wenku

托福阅读提分的5大技巧

托福阅读提分的5大技巧 大家在备考的时候要多根据托福阅读题型进行总结,多做托福阅读真题。这样在考试中就 能够根据以往的经验进行答题,既能提高速度又能提高效率。下面为大家整理了托福阅读 提分的5大技巧。 1.文章主旨的把握 首先,托福的每一篇文章都附加了标题,可以通过对文章标题格式,内容,可能应用的文 章书写格式三个方面对文章整体进行把握。 其次,每篇文章的长度由原来的300-400增长到了现有的700字左右,且段落由原有的2- 4段增长到现有的5-10段,那么对于文章主旨的把握能力就显得无比重要。而要做到在短短的3-4分钟以内完成这件事情,就要求我们对段落结构,段落大意,以及段间结构即文 章大纲的把握做到精准的程度。 2.泛读能力 所谓托福阅读泛读能力是指得在短时间以内对一篇文章内容迅速把握。在对文章段落主旨 句的阅读中,我们需要读的内容约有8-15句话左右,在3-4分钟以内完成对这些句子的 阅读并总结文章大纲,就要求我们对于托福句子式结构熟识于心。而托福阅读中,句子长,成份杂一直以来都是大家在阅读上遇到的最大障碍之一。解决这个问题的方法,可以采用 泛读技巧中的主句阅读方式,即对读到的每个句子进行结构分析,找出主句,再补充其它 成份的细节内容。 当我们对段内句子的主要意思,讲述对象,及讲述方向有所了解之后,后期解题过程中使 用到的答案定位(或关键词定位)便可以达到快,准,稳的效果。 把握住了文章主旨就得到了文章的写作方向与目的,辅以段落间的关系,会使得解题过程 轻松无比。 3.段落结构 文章写作过程中,为了清楚的表达中心思想,会采用不同的段落结构,而结构的选取与文 章类型及内容无关,仅是选取一种最为清晰的表达方式。段落内部结构从大体上来讲可以 分为总---分---(总)的分点并列结构,或者总---分的观点递进阐述结构。相对来讲前者 更赋逻辑性,而后者因其逻辑性较差而导致在阅读过程中难度系数相对较大。当大家对段 落内部结构的分析日渐成熟的时候,便可以对段落主旨大意总结的驾驭做到轻车熟路,进 而节约阅读时间。 4.句子结构

员工通用素质辞典

通用素质辞典

目录 1.01商业意识 0 1.02结果导向 (1) 1.03成本意识 (2) 1.04成就导向 (3) 1.05风险控制 (5) 2.01客户导向 (6) 2.02战略规划 (7) 2.03前瞻思维 (9) 2.04全局观念 (10) 3.01质量导向 (11) 3.02技术应用 (12) 3.03关注细节 (13) 3.04计划执行 (14) 3.05组织协调 (15) 3.06决策能力 (16) 3.07指挥控制 (18) 3.08培养指导 (19) 3.09团队激励 (21) 3.10团队合作 (22) 3.11承受压力 (23) 3.12问题解决 (24) 3.13创新能力 (25) 4.01口头表达 (26) 4.02书面表达 (27) 4.03人际理解 (28) 4.04影响能力 (29) 4.05人际交往 (30) 4.06信息收集 (31)

4.07分析判断 (32) 4.08敬业负责 (33) 4.09坚持不懈 (34) 4.10自控能力 (35) 4.11积极主动 (36) 4.12学习能力 (37) 4.13诚信正直 (38)

1.01商业意识 密切关注市场、客户和竞争对手的状况,能够积极和有效地创造和维持商业价值,谋求企业长期利益最大化。 行为特征: 1.能够对产生商业价值的驱动因素进行精确分析。 2.随时关注市场环境和客户需求的变化。 3.能够将时间和精力集中在真正创造商业价值的行动上。 4.为了获取商业利益,必要时能够做出一些强硬的决策。 5.能够不断提供满足客户需求或引导客户需求的产品和服务。 行为分级: 零级: -不能充分客户需求,按照自己的想法提供产品或服务。 -经常做出被后来事实证明商业价值很低的决策。 -有时为了短期利益,牺牲公司的长期利益。 一级: -能够收集一些明显的、易于获得的有关市场、客户和竞争对手的状况的信息。 -能够模仿或借鉴他人的成功做法,寻找商业机会或谋求企业利益最大化。 -很少关注他人或下属的工作是否为公司真正创造价值。 二级: -密切关注市场环境、客户需求的变化以及产品技术的发展趋势,有意识地收集和分析市场信息。 -一般能够对市场趋势做出正确的判断,顺应发展潮流,及时推出新产品或新服务,并积极防御可能可出现的危机,取得令人满意市场成绩。 -能够根据市场竞争的需要或客户的要求,对内部流程和管理进行一些局部的改进或完善。 三级: -建立收集市场信息的机制或稳定的多种信息渠道,定期对市场信息进行分析和判断,对市场需求的变化高度敏感。 -善于捕捉或挖掘市场潜在的机会,总是能够不断提供满足客户需求或引导客户需求的产品和服务,抢占市场先机。 -致力于追求企业长期价值的提升,平衡公司的长期利益和短期利益之间的关系。 -能够对产生商业价值的驱动因素进行精确分析,对内部流程和管理进行系统改造和提升,将资源集中在真正创造商业价值的行动上。 -为了获取商业利益,能够排除各种干扰,必要时能够做出一些强硬的决策。

托福阅读做题技巧

托福IBT阅读总述 细节题 反面细节题 词汇题 指代题 推断题 修辞目的题 句子简化题 句子入位题 文章总结题 表格题 题型特点 1. 所占比重:3-6/14,30% 事实信息题的数量是十大题型当中最多的,占到整个考题量的1/5-1/4,而且以考察考生对于细节容的理解程度 2. 提问方式 According to the paragraph, which of the following is true of X? The author’s description of X mentions which of the following…?

According to the paragraph, X occurred because… According to the paragraph, X did Y because… According to the paragraph, why did X do Y? 解题步骤 细节题的答案直接出现在原文中,正确答案是原文的同义改写 ?1、从题干当中提取关键词(问什么,提到什么) ?2、带着关键词回原文定位 ?3、对定位句进行同义改写(80%)或者针对TS(topic sentence)+D(details)进行总结归纳(20%) ?4、运用直选法选出正确答案(排除答案当中的错误项) 能进行定位的: Key word原则:n>v>adj./ adv. n:人名;地名;时间名词;专属名词;数字 选择围小的当定位词:n1 of n2 of n3… n1 in n2 in n3… n1>n2 >n3… 无法进行定位的: 1.TS+D (Topic Sentence+Details)方法,捕捉抽象概念; 1.并结合选项排除 题型特点 1.所占比重:0-2/14,14% 事实信息题出题比重并不是特别大,但是往往成为考生在考试当中的失分点。 2. 提问方式 According to the passage, which of the following is NOT true of X? The author’s description of X mentions all of the following EXCEPT… 三种考查方式

新托福阅读题型介绍与技巧汇编

新托福阅读题型介绍 一、细节题 特征:没有特征(因为其他题型都有各自的特征) 数量:每篇3-6题 难度:变化很大 策略:随机应变 二、选非题 特征:NOT/EXCEPT 数量:每篇1题 难度:较低 策略:一定要做对 三、推理题 特征:infer、imply 数量:每篇1-2题 难度:很高 策略:可以放 四、修辞题: 特征:(1)题干与原文被打上了阴影 (2)个选项的开头为TO+关键动词(这些动词代表某个修饰手法,这样的动词很少,所以遇到都要记住)PS:这类题目有可能会变形 五、词汇题 特征:(1)题干与原文被打上了阴影 (2)以the word/phrase开头 数量:每篇3-6题 难度:非常简单 策略:一定要做对

六、指代题 特征:(1)原文与题干被打上阴影 (2)打上阴影的是某个代词 数量:1题 难度:较低(可以直接测试语法能力) 策略:要做对 七、复述题 特征:(1)原文中一个完整的句子被打上阴影 (2)题干为:which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect answer choices change the meaning in important ways or leave out essential information. 数量:1题 难度:很难或者很简单 八、插句题 特征:黑色小方框(■) 数量:1题 难度:较低 策略:要做对 九、归总题 特征:两排六个选项 数量:1题 难度:1分很简单,2分有点难 策略:保1争2 新增题型(参考TPO5):四选二题型:是细节题的变形 全文归纳题:可以去归总题找答案

托福阅读技巧

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先读题目再读文章(相应部分)然后做题 它们又能衍生变化出两种做题顺序:读一段文章,做相应的题目,然后再读一段,再做相应的题目;读文章各段首句,然后看题目,再 找文章内相应部分做题 对于广大非牛来说,可能“读文章各段首句,然后看题目,再找文章内相应部分做题”会比较合适,读各段首句可以粗略掌握文章 大意和结构,做题再看内容再做能大大降低“工作量”,但是这种 做法不利于对全文的消化吸收,从而不利于做总结题,也可能会遗 漏文章内的一些细节而导致做错细节题。而新托福目前反馈大都是 顺序出题的,所以建议练习时就尽量往“读一段做相应题目,再读 一段再做相应题目”这一顺序去靠拢,可以对文章有全面的把握, 虽然总量上还是要读完全文,但是对大脑的短期记忆的负担要比通 读全文再做题目小很多。 托福阅读题型破解 阅读一般来说是中国人的强项了,也是拿分的主力。如果你口语不牛,作文一般,还想考到100分,那么阅读应该保证在28分以上。 在IBT阅读中,甚至可以扩展到ETS所有考试的阅读题目中,如果要用一个词来概括的话,那就是paraphrase,意译。 无论是题干还是正确选项,大都能在原文中找出一句话来与之相对应。即题目是原文的意译。这种意译是通过同义词来完成的。即 题干中多用近义词来对原文中的句子进行替换,来达到提出问题或 者提出正确答案的意思。准确把握意译,是多数题目中准确在原文 中定位信息、或者在迷惑选项中选出正确的那个,都有着重要的作用。在后面的文章里我会结合实例解释这一点。 关于先看题目还是先看文章的问题。也就是做题时间安排的问题。小站君个人习惯是先用5—7分钟的时间通读全文,然后平均每个问 题有1分钟的时间来回答。由于对问题的回答建立在了熟悉全文的 基础上,每个问题又有足够的时间返回全文,每个选项都一一进行 斟酌。我认为这样准确率比较高。但有的朋友本着居家过日子的心,认为1000多字的文章只出十几个题,必然有一些信息是没用的。这

人员素质辞典

人员素质辞典 The latest revision on November 22, 2020

人员素质辞典二零零六年十一月

领导 能力 管理能力

目录

团队领导 定义: 通过授权、激励等管理手段充分发挥团队成员优势,促进团队合作,解决人员冲突,带领团队成员完成工作目标。 关键点: 激发团队成员的动力,营造良好团队氛围。 行为分级: 一级:告知团队 -主动向团队成员传达某项决定的内容或工作任务的要求,清晰地表明工作的原则和权限范围,明确要完成的目标。 -以正式的渠道公告授权内容,向团队成员解释其中的过程或原因,确保他们了解必要的信息,帮助他们获得配合和减少冲突。 二级:维护群体 -确保团队的合理需要得到满足,并为团队成员的工作开展争取所需要的各种信息、资源。 -保护自己领导的团队及其声誉,采取各类实质性的举措让团队成员感受到自己对团队利益的重视。 三级:做好表率 -通过以身作则,向团队成员示范自己所期望的行为,使他们接受自己为团队设定的使命和目标,以及做出的安排和决定等,确保集体的任务能够完成。 -在必要的时候与下属同甘共苦,赢得下属的信赖。 四级:激发士气 -针对不同的情况,灵活采取不同的激励手段,激发下属的热情。 -善于描绘激动人心的使命和目标,使下属充满热情和希望。 -采用各种方式来提高团队的士气,如迅速解雇绩效不佳者,对工作流程进行科学、合理的调整等,以改进团队的工作效率,加强集体向心力。 五级:创造氛围 -成为团队的精神领袖,从做事方式上深入影响下属,利用个人人格魅力或突出的工作能力在下属和同事间树立威信。 -鼓励团队成员之间互相帮助,创造坦率、温暖、合作的团队氛围。

能力素质模型词典

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haygroup素质辞典

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人员素质辞典二零零六年十一月

目录 1.01团队领导3 1.02战略规划4 2.01计划执行4 2.02决策能力5 2.03培养指导6 2.04影响能力7 2.05组织协调8 3.01成本意识8 3.02客户导向9 3.03专业性10 4.01创新能力11 4.02分析式思维11 4.03归纳思维12 4.04信息收集13 4.05学习领悟14 5.01成就动机14 5.02沟通能力15 5.03关注细节16 5.04积极主动16 5.05坚持不懈17 5.06灵活性18 5.07人际交往18 5.08自控能力19 5.09自信心20 6.01诚信正直21 6.02敬业精神22 6.03全局观念22 6.04团队合作23 6.05责任心24 6.06组织承诺24

1.01团队领导 定义: 通过授权、激励等管理手段充分发挥团队成员优势,促进团队合作,解决人员冲突,带领团队成员完成工作目标。 关键点: 激发团队成员的动力,营造良好团队氛围。 行为分级: 一级:告知团队 -主动向团队成员传达某项决定的内容或工作任务的要求,清晰地表明工作的原则和权限范围,明确要完成的目标。 -以正式的渠道公告授权内容,向团队成员解释其中的过程或原因,确保他们了解必要的信息,帮助他们获得配合和减少冲突。 二级:维护群体 -确保团队的合理需要得到满足,并为团队成员的工作开展争取所需要的各种信息、资源。 -保护自己领导的团队及其声誉,采取各类实质性的举措让团队成员感受到自己对团队利益的重视。 三级:做好表率 -通过以身作则,向团队成员示范自己所期望的行为,使他们接受自己为团队设定的使命和目标,以及做出的安排和决定等,确保集体的任务能够完成。 -在必要的时候与下属同甘共苦,赢得下属的信赖。 四级:激发士气 -针对不同的情况,灵活采取不同的激励手段,激发下属的热情。 -善于描绘激动人心的使命和目标,使下属充满热情和希望。 -采用各种方式来提高团队的士气,如迅速解雇绩效不佳者,对工作流程进行科学、合理的调整等,以改进团队的工作效率,加强集体向心力。 五级:创造氛围 -成为团队的精神领袖,从做事方式上深入影响下属,利用个人人格魅力或突出的工作能力在下属和同事间树立威信。 -鼓励团队成员之间互相帮助,创造坦率、温暖、合作的团队氛围。

能力素质模型:素质辞典(运营类)

运营类人员素质辞典

运营类人员素质模型运营类人员的素质模型如下:

目录 6.05责任心 0 2.01计划执行 0 6.03全局观念 (1) 2.05组织协调 (2) 5.02沟通能力 (3) 6.02敬业精神 (3) 5.03关注细节 (4)

6.05责任心 定义: 认可自己的工作职责,认真的采取行动去完成这些职责,并自发自觉地承担工作后果。 关键点: 所负责的工作出现问题时不推诿,敢于承担责任并设法解决问题。 一级:明确职责 -明确自己的工作职责和角色,认识到自己承担工作的重要性。 二级:主动落实 -以一种积极主动的姿态处理事情,对职责范围内的工作进展情况及时进行核查,对发现的问题采取必要的行动,以保证工作按要求标准完成。 三级:尽职尽责 -当工作中面临需要同时处理职责内和职责外的任务时,能主动采取应对措施,保证不因为职责以外的任务而影响职责内工作的完成情况。 四级:光明磊落 -主动公开地承担本职工作中的责任问题,不欺上瞒下,并及时主动的采取补救预防措施,防止类似的问题再次发生。 - 五级:克己奉公 -支持公司战略目标的实现,即使面临巨大压力或个人利益受到损失时,仍能不折不扣地完成工作。 2.01计划执行 定义: 工作中能够迅速理解上级意图,形成目标并制定出具体可操作的行动方案,通过有效组织各类资源,和对任务优先顺序的安排,保证计划的高效、顺利实施,并努力完成工作目标的能力。 关键点: 制定可操作性工作计划,区分轻重缓急,克服困难完成工作目标。 行为分级: 一级:明确目标

-能够根据公司或上级的明确要求,结合本岗位的职责,确定自己工作的短期目标。 二级:目标分解 -根据具体目标,将工作分解为若干的关键可操作性步骤,区分轻重缓急,设立优先次序,形成任务时间进度表。 三级:资源配置 -能够准确评估实现工作目标所需的人、财、物等资源,并做出资源配置的可行性方案。 四级:监控与反馈 -建立监控和反馈机制,能够从整体上把握计划实施的进程。 五级:灵活应变 -在工作计划中能够预留弹性或额外工作时间,以应对意外事件。 -主动评估工作中可能存在的风险,随时准备应对各种障碍和问题,并提前制定应变方案,以确保工作任务总是按时、保质地完成。 6.03全局观念 定义: 开展工作或进行决策时,能够考虑他人、其他部门或公司整体的情况,从组织的整体或长远利益出发,顾全大局,为了整体利益能够牺牲局部利益或个人利益。 关键点: 无本位主义,考虑和处理问题时兼顾其他部门和公司整体利益。 行为分级: 一级:认清局势 -明确了解组织中的整体战略目标和运营支持部门的目标及个人目标,企业整体利益与局部利益、个人利益之间的关系。 -理解组织的整体利益与局部利益、个人利益之间会不可避免地出现矛盾。 二级:服从组织 -关心组织的整体发展和其他部门、岗位的工作情况。 -在组织要求局部利益或个人利益做出让步时,能够进行自我调整,以服从大局。 三级:遵从规则 -遵从企业运作中的各种规则和组织的整体战略方向,从组织的整体和长远利益出发考虑本部门的工作,不会为局部小利而轻易打破规则和已经建立的平衡。

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