attitude是什么意思
文章编号:100022618(2004)0320217207
收稿日期:2004206207
基金项目：国家重点基础研究发展计划项目(2002C B412309)
作者简介：雷安平(19682)，女(汉族)，湖北省罗田县人，深圳大学博士.E 2mail :bioaplei @szu 1edu 1cn
Properties of polycyclic aromatic hydrocarbons and their toxicity on algae
L EI An 2ping
C ollege of Life Science Shenzhen University Shenzhen 518060P.R.China
Abstract :C ontamination of polycyclic aromatic hydrocarbons (PAHs )in the environment is a rious public health prob 2lem and the im pact of PAHs on human beings and ecosystems has attracted increasing public and academic concern.H ow 2ever ,information related to the properties of PAHs and their toxicity on algae ems to be meager and widely scattered in spite that algae rve as major primary producers and play an im portant role in aquatic ecosystems ,and any changes in al 2gal com
munity are likely to lead to major ecological conquences in aquatic ecosystems.The prent review first describes the chemical structures and general properties of PAHs ,then briefly introduces the s ources and fate of PAHs in the envi 2ronment and finally encom pass the toxicity of PAHs on algae ,with em phasis on the activation of the toxicity of PAHs and algal species 2specific differences in nsitivity to PAHs.
K ey w ords :polycyclic aromatic hydrocarbons (PAHs );properties ;toxicity ;algae
1 Chemical structures and general proper 2ties of PAHs
111 Chemical structures
P olycyclic aromatic hydrocarbons (PAHs )are a group of aromatic com pounds containing tw o or m ore fud benzene rings in linear ,angular ,or cluster structure.S ome of them can be considered heterocyclic m olecules with the substitution of an aromatic ring carbon by nitro 2gen ,oxygen ,or sulphur [1].The lipophili 2city ,environ 2mental persistence and genotoxicity increa as the m olecu 2lar sizes of PAHs increa up to 4or 5fud benzene rings while toxicological concern shifts towards from acute to chronic toxicity ,primarily carcinogenesis as the number of benzene rings incread from 2to 5[2,3].PAHs with four
or m ore fud rings are less s oluble ,m ore stable ,and
m ore recalcitrant.
112 G eneral properties 2ubiquitous ,bioaccumulative and persistent pollutants
PAHs are ubiquitous in the environment and are found in high concentrations in many industrial sites ,par 2ticularly tho ass ociated with petroleum ,gas 2production and w ood 2prerving industries [4].M ost PAHs are practi 2cally ins oluble in water.PAHs ,like many other lipophilic organic environmental pollutants ,have low vapor pressure and high octanol 2water partition coefficients [3].PAHs are rapidly abs orbed by particulate matter and by living organ 2isms.In water ,PAHs may be prent in the vapor pha ,diss olved pha ,micelle form ,s orbed to “diss olved ”or colloidal organic matter ,s orbed to particles ,or incorporat 2ed into biota [5].Due to their lipophilic and accumulative
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nature,PAHπs bioavailability is low and they are persistent within ecosystems.They are relatively stable,recalcitrant, m ore difficult to degrade than many other organic com2 pounds,and have long half2life time in nature,especially tho PAHs with up to4or5fud benzene rings[2]. S ome PAHs are mutagens and carcinogens,and16PAHs are designated by USEPA as“Priority pollutants”[6].
2 S ources and fate of PAHs in the envi2 ronment
211 Sources of PAH s in the environment
S ources of PAHs in the environment include both nat2 ural and anthropogenic inputs[4].Naturally occurring PAHs which are in the terrestrial environment from forest fires,v olcanic activity,and synthesis by plants and mi2 croorganisms make a minor contribution to the PAH con2 tent in the environment.The anthropogenic PAHs emitted from burning of fossil fuels,refu combustion,and agri2 cultural burning are major contributors to the PAH pool (>90%of emissions from the s ources)[4].The PAHs emitted from autom obile exhausts are localized along road2 ways while tho
emitted from jet aircraft and power plants may be spread over long distances.Neither autom obile nor jet engine exhausts are major contributors to the environ2 mental burden of PAHs on a global scale.Waste products from industries and municipalities are significant contribu2 tors to s oil PAHs in is olated areas.Anthropogenic combus2 tion activities are principal s ources of PAHs to s oils in in2 dustrialized countries via atm ospheric deposition.As a re2 sult,s oil concentrations tended to increa over the last 100～150years,particularly in urban areas[7].
The concentrations of PAHs in the environment vary significantly,depending on the level of industrial develop2 ment and contamination with petroleum products.F or ex2 am ple,in s oil it could range from5μg・kg-1in an unde2 veloped area to1179×106μg・kg-1at an oil refinery[8]. In H ong K ong S AR,total PAHs are widely distributed in diments,with background concentration of total PAH at around40to60μg・kg-1wet weight,but incread to116μg・kg-1wet weight in Victoria Harbour and veral other contaminated areas,and the concentrations were up to1159μg・kg-1wet weight in typhoon shelters with substan2 tial contamination[9].
价格用英语怎么说212 F ate of PAH s in the environment
The possible fate of PAHs in the environment include abiotic and biotic process,of which v olatiliza
tion,pho2 tooxidation,chemical oxidation,bioaccumulation,ads orp2 tion to s oil particles,leaching and microbial degradation are the main process[3].
In the ca of photochemical activation,PAHs abs orb ultra2violet light energy and are subject to photolytic acti2 vation or breakdown[10].Park et al.found that v olatiliza2 tion was negligible,except for naphthalene and substituted naphthalenes[11].PAHs with three and m ore rings tend to be strongly ads orbed to s oil particles.Strong s orption cou2 pled with low water s olubility and very low vapor pressures makes leaching and v olatilization insignificant pathways of PAH dissipation.The microbial metabolism is the major biotic process that results in the decontamination of PAHs in nature[12].A wide variety of bacteria,fungi and algae have the ability to metabolize PAHs.Bioconcentration is als o an im portant process which affects the fate of hy2 drophobic com pounds.Certain environmental factors such as tem perature,pH,nutrients,oxygen and water avail2 ability,salinity and s oil type,etc.w ould affect the fate of PAHs in the environment[2,13].
3 T oxicity of PAHs on algae
Since s ome of the PAHs are carcinogenic or muta2 genic[6],many data related to their possible health effects on mammalian and procary otic cells have been obtained. There remains,however,a n
eed for the validation of the toxic effects of PAHs on microalgae.Although algae do not constitute a major human food crop,they are esntial com ponents of aquatic food chains and play im portant roles in aquatic ecosystems.
311 Activation of the toxicity of PAH s
PAHs can be activated by either abiotic or biotic pro2 cess[10,14,15].In the ca of photochemical activation, PAHs abs orb light due to their strong abs orption bands in the ultraviolet2A(UV2A;3202400nm)and ultraviolet2B (UV2B;290～320nm)regions of the s olar spectrum,the
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toxicity of PAHs is induced and greatly enhanced by UV radiation[14,16].The com pounds are m ore reactive and hazardous following photon abs orption.It has been report2 ed that light significantly incread the phototoxicity of PAHs to higher plants and microalgae[10,17].The effects of lected PAHs on the growth of a green microalga,Se2 lenastrum capricornutum,in three light regime were re
port2 ed by C ody et al[18].They found that in g old fluorescent light,benzo(a)pyrene(BaP)(12mg l-1),13BaP metabolites(40mg l-1),benzo(a)anthracene(40mg l-1)and anthracene(40mg l-1)had no effect on algal growth,however,in cool2white fluorescent light,30%in2 hibition on algal growth was found at01025mg l-1BaP, 1183mg l-1benzo(a)anthracene and7114mg l-1an2 thracene.It is apparent that photoinduced phytotoxicity of PAHs is a general phenomenon.
In animals,in addition to UV light activation,PAHs can als o be activated by biotic process such as cy2 tochrome P2450mediated m onooxygenation[15].F or exam2 ple,BaP is activated to reactive intermediates by cy2 tochrome P2450mediated metabolism.The mechanisms in2 v olve a22electron oxidation or a12electron oxidation step. S ome metabolites such as trans27,82diol29,102epoxide can produce bulky DNA adducts and DNA strand breaks, and s ome cation radicals can bind themlves to DNA and other macrom olecules in animals[19].The degree of DNA adducts in tissues of target organisms have been ud to asss the degree of genetic damage resulting from expo2 sure to environmental carcinogens.Xu et al(1999) dem onstrated that DNA adduct levels were related to tissue concentrations of BaP and total PAHs in individual ani2 mals[20].Becau s ome intermediates are m ore toxic than the parent PAHs,the verity of PAH hazards is possibly underestimated,and it is necessary to consider the toxicity of the intermediates when asssing the environmental risks of PAHs[10].
312 The algal species2specific differences in nsitivi2 ty to PAH s
As for the toxicity of PAHs on algae,s o far only growth and photosynthetic respons of a few PAHs on a limited algal species have been studied(T able1).The species2specific differences in nsitivity to PAHs and N2 heterocyclic PAHs are potentially large[21～23].S ome re2 arch examined the effects of BaP in white light on the growth of ven microalgal species and reported that three species,Ankistrodesmus braunii,Scenedesmus acutus and Selenastrum capricornutum,were growth2inhibited whereas the growth of the other four species,Anabaena flosaquae, Chlamydomonas reinhardtii,Euglena gracilis and Ochromonas malhamensis,were unaffected[21～22].Simi2 larly,the toxicity of a N2heterocyclic PAH acridine on ven microalgal speices varied am ong species,and the obtained EC50values ranged from0108mg l-1for Nitzschia sigma to0178mg l-1for Chlamydomonas euga2 metos and Navicula salinarum[21].Variations in sizes, shapes,com position of cell wall and cell membrane,and growth rates of different algal species might affect their re2 sistance to pollutants.The origins of the microalgae,from polluted or non2polluted area,might als o affect their resis2 tance.F or instances,Wuertz ported that the mi2 croalgae is olated from polluted area have higher resistance to tributyltin(T BT)than that from non2polluted area be2 cau of their adaptation and tolerance to stress in contami2 nated water[24].H owever,Dijkman et al.found
that the N2heterocyclic PAH acridine toxicity on microalgae was neither related to their tax onomical background(green al2 gae versus diatoms)nor to the original habitat of the species(planktonic or benthic,eutrophic or olig o2mes o2 trophic)[23].M ore detailed studies must be conducted to understand the variation of PAHs toxicity to different mi2 croalgal species.
The toxic effects of pyrene on ven microalgal species,namely,Chlamydomonas sp.,Chlorella minia2 ta,Chlorella vulgaris,Scenedesmus platydiscus, Scenedesmus quadricauda,Selenastrum capricornutum, and Synechocystis sp.were studied in our lab[25].Three species were commercial available and the other four species were local is olates.Results showed that S.
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T able1 Toxicity of PAH s on different algal species
表1 多环芳香烃对不同藻类的毒性
C om pounds Organisms T oxic effects References
N2heterocyclic PAHs:Acridine Scenedesmus acuminatus,Selenastrum
capricornutum,Chlamydomonas euga2
metos,Staurastrum chaetoceras,
Staurastrum manfeldtii,Navicula sali2
narum,Nitzschia sigma EC50values(bad on cell numbers)
ranged from0108to0178mg l-1.
Dijkman et al.,
1997
Anthracene;Benzo(a)an2 thracene(BAA)Selenastrum capricornutum30%growth inhibition at7113mg l-1
subjectmatterof anthracene and1182mg l-1BAA.
英语词典在线Schoeny et al.,
1988
Benzo(a)pyrene(BaP)Selenastrum capricornutum,
Scenedesmus acutus f.Alternans,
skiprope
Ankistrodesmus braunii,Chlamy2
domonas reinhardtii,Ochromonas mal2
hamensis,Euglena gracilis,Anabaena
flos2aquae G rowth inhibition on the first three
species,no inhibition on the other four
species.
Schoeny et al.,
浪漫的老鼠1988;War2
shawsky et al.,
1995
Naphthalene Chlamydomonas angulosa G rowth:61%cells were killed in satu2
rated naphthalene.Photosynthesis:im2
mediate and alm ost com plete loss.
S oto et al.,1975
Diel exhaust particle extracts Chlamydomonas reinhardtii D o2dependent growth retardation or
cell death.Develop resistance after ac2
climatization.Liebe&F ock, 1992
7H2Dibenzo[c,g]carbazole (DBC);Dibenzo[a,j]acridine (DBA);7,122Dimethylbenzo [a]anthracene(DM BA);An2 thracene;Pyrene Chlamydomonas sp.,Chlorella minia2
ta,Chlorella vulgaris,Scenedesmus
platydiscus,Scenedesmus quadricauda,
Selenastrum capricornutum,and Syne2
chocystis sp.
DBC and BaP were phototoxic to Se.
capricornutum,pyrene was toxic to S.
quadricauda;the other PAHs were not
phototoxic to all the other species.绯闻女孩第一季下载
Warshawsky et
al.,1995;Lei,
2003
quadricauda was the only species nsitive to pyrene am ong the ven microalgae examined within the pyrene concentrations investigated.The cells of S.quadricauda are attached side by side to form colonies of4cells(s ome could be2,8or16cells),arranged linearly,with spiny projections in terminal cells.The spiny projections were u2 nique for this species.The tw o species,S.platydiscus and S.qua
dricauda,belonging to the same genus, Scenedesmus,exhibited difference in their resistance to pyrene.The three commercially available species, C. vulgaris,S.quadricauda and Se.capricornutum,als o showed difference in their susceptibility to pyrene.It is difficult to conclude why such differences occurred, whether this is related to their m orphology,tax onomic groups,or origins,partially becau the diversity of the lected microalga species did not cover a wide range of tax onomic groups and partially becau very few data con2cerning pyrene toxicity on microalgae were available in the literature.The toxicity of pyrene to microalgae was only reported in1995,and only one microalgal species,Se. capricornutum,was tested,which revealed that pyrene was not phototoxic[22].M ore detailed studies must be con2 ducted to understand the variation of pyrene toxicity to dif2 ferent microalgal species.In addition to their different m orphology,tax onomic groups and origins,difference in metabolizing pyrene am ong microalgal species was found in our study[25,26].Se.capricornutum was the m ost efficient species in pyrene metabolism followed by S.platydiscus, and C.vulgaris was the least efficient species[26].It is clear that the susceptibility of S.quadricauda to pyrene was not coupled with its intermediate efficiency in metabolism of this com pound.The results suggested that microalgaeπs nsitivity or resistance to pyrene might not be related to their ability in metabolizing pyrene.
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313 Developed resistance to PAH s
S ome algae might have developed resistance to PAHs in PAHs contaminated habitats.An algal species, Chlamydomonas reinhardtii could develop resistance to diel pollutant after a period of exposure[27].They found that at concentrations up to01125%(v/v),the diel exhaust particle extracts led to a do2dependent growth retardation,i1e1higher concentrations caud m ore cell death,however,after a prolonged lag pha,air2grown il2 luminated algae stresd with sublethal concentrations of the extracts adapted to the pollutants and further addition of toxic extracts up to a concentration of215%(v/v)did not affect algal growth or photosynthesis.S oto 2 ported that another algal species,Chlamydomonas angu2 losa,could develop resistance to a tw o2ring PAH(naph2 thalene),and algal growth resumed after veral days[28]. Further studies are necessary to elucidate the mechanisms causing the developed resistances to PAHs in algae.
R eferences:
[1]Harvey R G.P olycyclic Aromatic Hydrocarbons[M].New
Y ork:Wiley2VCH,1997.
[2]Cerniglia C E.Biodegradation of polycyclic aromatic hydrocar2
bons[J].Biodegradation,1992,3:3512368.
[3]Mackay D,Shiu W Y,Ma K C.I llustrated Handbook of Physi2
cal2chemical Properties and Environmental Fate for Organic Chemicals[M].Chela:Lewis Publishers,1992.
劳动节英语手抄报[4]Edwards N T.P olycyclic aromatic hydrocarbons(PAHs)in the
terrestrial environment———a review[J].J Environ Qual, 1983,12(4):4272441.
[5]McCarthy J F,R oberts on L E,Burrus L.Ass ociation of benzo
(a)pyrene with diss olved organic matter,prediction of K
(DOM)from structural and chemical properties of the organic matter[J].Chem osphere,1989,19:191121920.
[6]K eith L H,T elliard W A.Priority pollutants.I———a perspec2
tive view[J].Environ Sci T echnol,1979,13:162423. [7]Jones K C,S tratford J A,Waterhou K S,et al.Increas in
regionalism
the polynuclear aromatic hydrocarbon content of an agricultural s oil over the last century[J].Environ Sci T echnol,1989,23: 952101.
[8]Wild S R,Berrow M L,Jones K C.The persistence of
polynuclear aromatic hydrocarbons(PAHs)in wage sludge a2 mended agricultural s oils[J].Environ P ollut,1991,72:1412
157.
[9]C onnell D W,Wu R S S,Richards on B J,et al.Occurrence
of persistent organic contaminants and related substances in
H ong K ong marine areas:An overview[J].Mar P ollut Bull,
1998,36(5):3762384.
[10]Huang X D,Dix on D G,G reenberg B M.Incread poly2
cyclic aromatic hydrocarbon toxicity following their photom odi2 fication in natural sunlight:Im pacts on the duckweed Lemna gibba L.G23[J].Ecotoxico Environ Saf,1996,32(2): 1942200.
[11]Park K S,S ims R C,Dupont R R,et al.Fate of PAH com2
pounds in tw o s oil types:in fluence of v olatilization,abiotic loss and biological activity[J].Environ T oxicol Chem,1990, 9:1872195.
[12]Wils on S C,Jones K C.Bioremediation of s oil contaminated
with polynuclear aromatic hydrocarbons(PAHs):a review [J].Environ P ollut,1993,81:2292249.
[13]Hu Z L,Wu Y H,Luo X T.The coordination effect am ong
cell type trans formation factors of Haematococcus pluvialis [J].J of Shenzhen University Science and Engineering, 2002,19(3):8212(in Chine)
[14]Huang X D,Dix on D G,G reenberg B M.Im pacts of UV ra2
diation and photom odification on the toxicity of PAHs to the higher plant Lemna gibba(Duckweed)[J].Environ T oxicol Chem,1993,12:106721077.
[15]Shimada T,Nakamura S I.Cytochrome P2450mediated acti2
vation of procarcinogens and promutagens to DNA damaging products by measuring expression of umu gene in Salm onella typhimurium T A1535/pSK1002[J].Biochem Pharmacol, 1987,36:197921987.
[16]Ar fsten D P,Schaeffer D J,Mulveny D C.The effects of near
ultraviolet radiation on the toxic effects of polycyclic aromatic hydrocarbons in animals and plants:a review[J].Ecotoxicol Environ Saf,1996,33:1224.
[17]G ala W R,G iesy J P.Photo2induced toxicity of anthracene to
the green alga,Selenastrum capricornutum[J].Arch of Envi2 ronm C ontam T oxicol,1992,23:3162323.
[18]C ody T E,Radike M J,Warshawsky D.The phototoxicity of
benzo[a]pyrene in the green alga Selenastrum capricornu2 tum[J].Environ Res,1984,35:1222132.
[19]Bigger C A H,Cheh A,Latif F,et al.DNA strand breaks in2
duced by con figurationally is omeric hydrocarbon diol epoxides [J].Drug Metabol Rev,1994,26(122):2872299.
[20]Xu L,Zheng G J,Lam P K S,et al.Relationship between
tissue concentration of polycyclic aromatic hydrocarbons and DNA adducts in G reen2lipped musl(Perna viridis)[J].E2
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