2J

BulletinofGlaciologicalResearch20（2003）21−27⑥JapaneseSocietyofSnowandIce

Effect of cryoconite and snow a［gaJcommunities on surface albedo on marjtime glaciersin
SOuth Alaska
Nozomu TAKEUCHll，Shiro KOHSHIMA2and TakahiroSEGAWA2

1ResearchInstitutefor HumanityandNature，335Takashimacho，Kamigyo−ku，Kyoto−City，Kyoto602−0878Japan
2Dep．BiologicalSciences，GraduateSchoolofBioscienceandBiotechnology（c／oFacultyofScience），TokyoInstituteofTechnology，
2−12−100kayama，Meguro−ku，Tokyo152−8551Japan（ReceivedSeptember2，2002；RevisedmanuscriptreceivedSeptember30，2002）

Abstract

In order to evaluate the effect of cryoconite on surface albedo on glaciers，Surface albedo，Characteristics of cryoconite，and snow algalcommunities wereinvestigated on two maritime

glaciers；WorthingtonandMatanuskaGlaciersinsouthAlaska，U．S．A．Thesurfacealbedointheice
arearangedfromO．37toO．74andthemeanwasO．53．Theamountofcryoconiteontheglaciersurface
rangedfromO．2to14gm2andthemeanwas3．8gm．2．Organicmattercontentinthecryoconite
ranged froml．O to9．8％and the mean was4．7％．Snow algalcommunities on the glaciers were
dominatedbythreegreenalgae，WhichwereMesoiaenium br喝gYmii，Anqlonemanordenskioldiiand
Chhl〝叩domonasnivalis．ThecellvolumebiomassofthesnowalgaerangedfromO．015toO．056mLm▲2andthemeanwasO．039m￣2．Ascomparedwithaninlandglacier ofAlaska，Gulkana Glacier，theeffectofcryoconiteonglacialsurfacealbedoseemedtobesmallerinthetwomaritimeglaciersinthis
Study．Thesurfacealbedoishigherandamountofcryoconiteissmallerinthemaritimeglaciersthan
theinlandglacier．Theorganicmattercontentandalgalbiomassaresmallerinthemaritimeglaciers
thantheinlandglacier．Thesmalleramountofcryoconiteandalgalbiomassonthemaritimeglaciers
maybecausedbywashingofcryoconiteandalgaeoutoftheglaciersbylargeamountsofrunningmeltwateronthebareicesurface．Themeltwatercanbeproducedmoreonthemaritimeglaciers，Sincetheablationrateishigherthanontheinlandglaciersurface．

1．lntroduction

Cryoconiteisbiogenicsurfacedustontheglacial
Surfaceandiscommononmanyglaciersintheworld（Takeuchi，2002b；Takeuchiet al．，2001b）．Thereduc−tion of surface albedo increases the solar radiation

absorbed by the glacier surface and result in more
meltingoftheglacier．Sincetheorganicmatterinthe（e．g．Gajda，1958；Wharton et al．，1985）．Cryoconite
CryOCOniteis produced by the organismsliving on
usually consists of mineral particles and organic
glaciers，thebiologicalactivity ontheglacierwould
matter．Theorganicpartofcryoconiteisderivedfrom
affect thesurface albedo and ablation oftheglacierbiologicalactivityontheglacier andconsists oftheand then may affect shrinkage of glaciers．Recent
Organisms themselves，their dead bodies，and investigationsrevealedsubstantialthinningandtermi−
decomposed organic matter（humic substances）．The
nusretreatofglaciersinmanypartsoftheworld（e．
Organismsinclude snow algae，insects，ice worms， g．Arendt et alリ2002）．Thecryoconitemaytakepartprotozoa，andbacteria（e．g．HohamandDuval，2001）．
Oftheshrinkage ofglaciers．Thus，itisimportantto
They are special species adapted to the extremely
Study the formation processes of cryoconite on thecold environment and spend their whole lives on
glacier．

glaciers．Cryoconiteis formed as a result of their
biologicalactivityontheglaciers．
Surfacealbedoofsnowandicecanbereducedby

impuritiessuch as cryoconite（e．g．Warren and Wis−
COmbe，1980）．Cryoconite can thereby contribute toacceleration of melting of the glacier surface．Espe−
Cially，Organicmatterincryoconiteisopticallyeffec−

tiveonthealbedoreduction，Sincetheorganicmatter
is usually dark−COlored andlarge volume particles

Recent studieshave revealed thatcharacteristics

Ofcryoconitedifferamongglaciers．Forexample，aS
CryOCOniteonHimalayanglaciersisdark・COloredanddenselycoverstheglaciersurfaceintheablationarea（Kohshima et al．，1993；Takeuchiet alリ2001b），the
CryOCOnitesignificantlyreduces8−15％ofthesurface

albedo on the Himalayanglaciers．The melting rate
WaS repOrted to be3timeslarger than that of the

Surfacewithoutthecryoconite（Kohshimaetalリ1993）．

BulletinofGlaciologicalResearch

22

Snow line
0 SampIIngSito−−−−■■Glacior¶ow

Fig．1 Maps of Worthington and Matanuska Glaciersin

theChugachMountains，Alaska，Showingsamplingsites（WOl，WO2，andMAl）ontheglaciersurface．

In contrast，On SOme glaciersin Patagonia and theArctic，the amount of cryoconiteis sma11and theMountainsinsouthAlaska（Figs．1and2）onSeptem−
ber7L9，2000．WorthingtonGlacierisasmalltemper−

glaciersurfaceisratherclean（Takeuchietal．，2001a； ateglacier andflowswest to east from a mountain2001c）．Theeffectofcryoconite onsurface albedois peak（2550ma．s．1．）towardeastdowntotheterminus

Smallintheseglaciersprobablyduetolowbiologicalactivity．Furthermore，thecryoconiteonTibetangla−

CiershaspalebrownCOlorationduetolessamountsof

atanelevationofapproximately820ma．s．1．Thesize

Oftheglacierisapproximately8kmlongwithlkm

darkTCOlored humic substances（Takeuchiet al．，
2002b）．Thistypeofcryoconiteislesseffectiveonthe

Surface albedo due toits high reflectivity oflight．
Thus，theeffect ofcryoconite onthe surface albedo
differsamongglaciers．Thevariationofcryoconiteis
importanttostudytheglacialmassbalanceandheat

budget．However，information about cryoconite on

glaciersisstilllimitedandfactorsaffectingbiologicalactivity and the formationprocess ofcryoconite are
Stillunclear．

This paper aims to describe and understand therelation of the surface albedo，Characteristics of

CryOCOnite，andsnow algalcommunity ontwo mari−timeglaciersinsouthAlaska．Inthisstudy，thespec−

tralalbedoandamountofcryoconiteweremeasured
Ontheicesurfaceoftheglaciers．Thecharacteristicsof the cryoconite and snow algal community on theglacier surface were analyzedin alaboratory．The
resultsarecomparedwiththoseofaninlandglacierof
Alaska，Whichisindifferentgeographicalandclimate
COndition．

2．Studysitesand methods
TheinvestigationwascarriedoutontheWorthin−
gtonandMatanuskaGlacierslocatedintheChugach

Fig．2 View of Worthington（a，September，2000）and
Matanuska Glaciers（b，August2001）．The picture of
Matanuskawastakenayearafterthisfieldwork．The
Samplingsitesareshownineachpicture．

Takeuchiet al．

2ヲ

Wide．Thesnowlineatthestudiedtimewasapproxi− SekkeiCo．Japan）within3hoursoflocalsolarnoon．
The weather condition was cloudy on Worthington
matelyl150m a．s．1．Matanuska Glacieris along

valley glacier and flows from some mountain peaks

Glacier and clear on Matanuska Glacier．The mea・The size of the glacieris approximately130kmin
lengthwith3kmwide．Thesnowlineatthistimewas

made at30cm abovethesurface．Themeasuredarea

easilyaccessiblefromhighway．Mostofthesurfaceof

from the totalof reflectedirradiance of the surface

Thesesiteswererepresentativebareicesurfacesand
Safely accessible．Red snow was visually significant
duringthestudyperiodinthesnowareaabovesnow
lineonWorthingtonGlacier．
Thesurfacealbedo oneachstudysitewasmea−

Stainless−Steelscoop（approximately15×15cminarea（around3200−3700ma．s．1．）towardsnorth．Thetermi− Suredwavelengthswere12pointsinvisibleandnear
nusis at an elevation of approximately500m a．s．1． inferred region（400，450，500，550，550，600，650，700，
750，850，950，andlO50nm）．Themeasurementswere

approximately1650m a．s．1．Both the glaciers are WaSapprOXimately80cm2．Thealbedowascalculated

and that of a standard white reference plate．The
mean albedo was obtained from values of5different
Surfaces，Which were randomly selectedin an areasurement and ice sampling were carried out at two
SitesonWorthingtonGlacier（WOlandWO2）andone approximatelylOOxlOOm2ateachsite．
Inordertomeasuretheamountofcryoconiteon
Site on Matanuska Glacier（MAl），locating between
the glacier surface and organic matter content of
550mandlllOma．s．1．（Fig．1）．Thesurfacecondition
Of the sampling sites was bareice onboth glaciers． CryOCOnite，iceinsurfacelayerwascollectedwitha

both glaciersis bareice or snow（Fig．3）without
debris cover（rock and stone）．Surface albedo mea・

andl−3cmindepth）at the area wherethe spectral

albedo was measured．The five samples were coIT
lected at each studied site．The collected area onthe
surface was measured to calculate the amount ofSured with a portable photometer（mode12703，Abe CryOCOnite per unit area．Cryoconite also existed atthebottomofcryoconiteholes，Whicharewater−fi11ed

Cylindricaldepressionsontheglaciersurfaceofbothglaciers．Thesizerangedfrom7to13indepth，from

3to8indiameter．Thecryoconiteincryoconiteholes
also was collectedwith a pipetin five holes at eachStudiedsite．The collected samples weremelted andpreservedasa3％formalinsolutionin125mLcleanpolyethylene bottles to fix biologicalactivity．All
SamplesweretransportedbycartotheInternational

Arctic Research Center，University of Alaska Fair−banks，for analysis．In thelaboratory，the samples
Weredried（650C，24hours）inpre−Weighedcrucibles．

TheamountofcryoconiteperunitareaoftheglacierWaS Obtainedfrom the dryweight and the samplingarea．Then，the driedsampleswere combustedforl

hour atlOOO OCin an electric furnace，and weighedagain．The amount of organic matter was obtained
from the difference the weight ofbetweenthe dried

andcombustedsamples．Aftercombustion，Onlymin，

eralparticles remained．The composition of the
CryOCOnitewasexaminedwithanopticalmicroscope（NikonSMZ800andE600）．

InordertomeasurealgalbiomassontheglacierSurface，anOthersetofsurfaceicewascollectedwith

astainless−Steelscoop（ト2cmindepth）．Thecollectedarea on the surface was measured to calculate theFig．3 Thebareicesurfaceofeachglacier（a，SiteWO20n
Worthington Glacier；b，Site MAlon Matanuska Gla−
Cier）．Cryoconite（dark−COlored dust）can be seen to
COVerthesurfacepartly．

amount of the algalvolume biomass per unit area．
Thefivesampleswerecollectedatrandomlyselected
Surface at each studied site．The collected samples
Weremeltedandpreservedasa3％formalinsolution
inclean125mLpolyethylenebottles．Theseformalin
Samples were used for cellconcentration counting．
Foridentificationofalgalspecies，Othersampleswere
COllected and kept frozenin a cooler．Allsamples
were transported by car to the International Arctic

24

Bul1etinofGlaciologicalResearch

ResearchCenter，UniversityofAlaskaFairbanks，for MatanuskaGlacier（t−teSt：WOIvs．MAl，t＝4．56，t＝analysis．Thefrozensampleswerekeptat−50Cina 0．006＜0．05；WO2vs．MAl，t＝4．15，P＝0．003＜0．05）．

Figure4showsthespectralalbedooftheglacierSurfaceofstudysites．Thespectralalbedodecreased

freezer．

Thealgalbiomassofeachsitewasrepresentedby
the cell number per unit water volume and algal
VOlumeperunitarea．Cellcountsandestimations of
Cellvolume were conducted with an opticalmicro−

asthewavelengthincreased．Especially，atthesiteof

Matanuska Glacier in which the highest albedo was
Observed，thealbedowasparticularlyhighinshorter

SCOpe（Nikon E600）．The samples were stained with
O．5％erythrosine（0．1mL was addedto3mL ofthe

WaVelength（400−650nm）．
10

Sample）and ultrasonicated for 5 min toloosen

0，9Sedimentedparticles．50−1000JLLofthesamplewater

WaSfilteredthroughahydrophilizedPTFEmembrane

0．8

filter（poresizeO．5JLm，MilliporeFHLCO1300），Which

0．7

became transparent with water，and the number of

6algaeonthefilterwascounted（1−31inesonthefilter）．

0
マ
O
q
一
く

Thecountingwasconducted3−6times oneachsam−

ple．Fromthemeanresultsandfilteredsamplewater，
thecellconcentration（cellsmL￣1）ofthesamplewas
Obtained．Meancellvolumewasestimatedbymeasur−
ingthesizeof50−100cellsforeachspecies．Thetotal

40algal biomass was estimated by summing values
obtained by multiplying algal concentrations by the00meancellvolume．Thiscalculationwasdoneforeach

SpeCiesateachsite．ToobtainspatialbiomassateachSite，the totalbiomasswas represent as cellvolume

perunitareaofglaciersurface（JLLm￣2）．Community

StruCtureWaSrepreSentedbythemeanproportionof
each species to the totalalgalvolume at each sam−plingpoint．

5

8 吉‡8 宗 8 吉；8 吉；8 ヽr 『■ lの の の くD 卜＿ ト． のⅥ由v8length（nm）

○
の
の

0
0
の

読
の

︻
古
O
﹁

白
の
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Fig．4 Spectralalbedo of theice surface of the threeSampling sites on Worthington and Matanuska Gla．
ciers．The curves are the mean surface albedo of 5
surfaces at each site．
エフ（Ⅵ〟…（、／りブゞ／ん、∫（l／（、Jγ）（てけ血一口〃仙、gん7（、∫tりS

Thedryweightamountofcryoconiteonthebare

icesurfacerangedfromO．2to9．5gmL2（mean：4．Ogm￣2）forWorthingtonGlacier andfrom O．2to13．9g
3．JA／∂g（わ〆娩ggんzcわγ5〝，カcem￣2（mean：3．3gm￣2）for MatanuskaGlacier（Tablel）．There was statistically no significant difference
The surface albedo measured on both glaciers
WaSShowninTablel．ThealbedorangedfromO．37to between the studied sites（t−teSt：WOIvs．WO2，t＝O．58andthemeanwasO．46forWorthingtonGlacier，
1．96，P＝0．085＞0．05；WOIvs．MAl，t＝0．429，P＝and from O．55 to O．74 and the mean was O．66 for
0．679＞0．05；WO2vs．MAl，t＝0．809，P＝0．442＞0．05）．
Matanuska Glacier．Thereis statistically no signifi−
The mineralparticles containedin the cryoconite
Cant difference between two sites on Worthington
ranged from O．16to9．1g m￣2（mean：3．7gmL2）for
Glacier（t−teSt：Statistic tvalue（t）＝0．719，prObability
Worthington Glacier and from O．15to13．2g m￣2（P）＝0．49＞0．05）．However，aStatisticalanalysisshows（mean：3．2gm￣2）forMatanuskaGlacier（Tablel）．
3．Res山ts

that albedos for two sites on Worthington GlacierWere Significantly smaller than that of the site on

Organicmattercontentofthecryoconite onthe

bareicesurfacerangedfrom4Ato9．8％（mean：6，2％）

Tablel．Surface albedo and characteristics of cryoconite on Worthington andMatanuska Glaciers．SD＝Standard deviation．

WOI

WO2

MAl

mean（SD） mean（SD） mean（SD）

Surface albedo

O．48（0．04） 0．46（0．07） 0．66（0．08）

Amountofcryoconite （gm￣2） 2．10（2．61） 5．80（3．31） 3．35（5．92）
Mineral（gmL2） 1．97（2．47） 5．51（3．16） 3．19（5．66）
Organicmatter（gm−2） 0．14（0．14） 0．29（0．15） 0．15（0．26）
Organic matter content
5．8（2．1）
2．8（1．8）
6．6（2．2）（bareicesurface）（％）

COntentit（％）

3・8（0・3）

5・1（0・7）

4・1（1・0）

Takeuchiet al．

forWorthingtonGlacierandl．Oto4．5％（mean：2．8％）
for Matanuska Glacier（Tablel）．The content waslarger onWorthingtonGlacier than Matanuska Gla−cier．

Organic matter content of the cryoconite col−1ected from the bottom of cryoconite holes rangedガ

Thecommunitystructureshowedthatalgalcom・

munities on the glaciers were dominated by threegreenalgae（Fig．6）．Thespecieswere M．brewrenii，
A．noYdenskioldii，and C．niualis．Two Oscillator−

iaceae cyanobacteria were minor species on bothglaciers（1ess than2％）．The most dominant species
WaSdifferentbetweenthetwoglaciers．M．

from3．3to5．9（mean：4．4％）onWorthingtonGlacier，
from2．8to5．2％（mean：4．1％）onMatanuskaGlacierWaS dominant at both two sites on Worthington（Tablel）．The organic matter contentin the Glacier，While A．no7denskioldiiwas dominant on
CryOCOniteholeswasslightlysmallerthanthatofthe
Matanuska Glacier．Percentage of M．b昭greniiinbareice surface on Worthington Glacier，While theOrganicmattercontentincryoconiteholeswaslarger
than on the bareice surface on Matanuska Glacier．

However，the differences of organic matter content
betweenthecryoconiteholeandbareicesurfacewere
notstatisticallysignificantatanystudiedsite．

thetotalcellvolumebiomasswas70−81％onWorthin−gtonGlacierand26％onMatanuskaGlacier．Percent−ageofA．noYdenskioldiiwasllL14％onWorthington
Glacierand66％onMatanuskaGlacier．C．nivaliiwas
thethirddominanceonbothglaciers（717％）．
％

ユJゴJ日付（J如／（、り〃川川，巾・りJJ〟汀gんJlイl）JS％

Three species of Chlorophyta（green algae）andtwoofcyanobacteriawereobservedinthecryoconite
Onbothoftheglaciers．ThespecieswereMesohlenium＝J．ノ われ紺ナで〃′J．．4〃りイ（りけJ〃（J「▲4．ノ 〃りJマムりJ∫かりんJメナ

ChklnWdbmonas（C．）nivaliiasgreenalgae，andtwo

Oscillatoriaceae cyanobacteria．The three species ofgreenalgaehavebeenreportedascommonalgaeon
glaciersinNorthernHemisphereaswellasinAlaska（e．g．Yoshimura et alリ1997；Kol，1942）．

Thetotalcellvolumebiomassofthesnowalgae

WaSgenerallysmallonbothglaciers（Fig．5）．Itranged
fromO．0004toO．24mLmL2（mean：0．051mLm¶2）forWorthingtonGlacier，fromO．OtoO．048mLm￣2（mean：
0．015mL m．2）for Matanuska Glacier．There was

Statistically no significant difference between the

％
％
％
％

ロ〟．b01W何州％

ロA．〃mね∩5kわノd〟％田C．〃／v8〟8●0剖剖ねIolね甜dn†■0ざ鵬炊〉血即2

％
％
％
∞
錮
8
0
乃
駈
5
0
4
0

WOI

3
0

WO2

MAI

G山bn8

Sib

加
1
0

Fig．6 Communitystructureofsnowalgaeofeachstudied
SiteonWorthington and Matanuska Glaciers（propor−
0tion ofcellvolumebiomass），Showingwiththat ofan
inlandglacier（Gulkana Glacier）in Alaska（Takeuchi，
2002a）．

Studied sites（t−teSt：WOlvs．WO2，t＝0．194，P＝0．801＞0．05；WOIvs．MAl，t＝0．854，P＝0．441＞0．05；
WO2vs．MAl，t＝1A5，P＝0．186＞0．05）．
4．Discussion

Thesurfacealbedoonthestudiedtwoglaciersis
almost equivalent to the albedo of clean bare ice

SurfaceofO．34−0．51byPaterson（1994）．Thespectral
albedo of the studied sites alsoindicates cleanice

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Surface；namely，thedecreaseofspectralalbedowith

WaVelengthobservedonthetwoglacierisacharacter−isticfeatureoftheclearglacialice（Zengetal．，1984）．

Thus，itissuggestedfromthisstudythattheeffectof

CryOCOnite onthe surface albedoissmallonthe two

glaciersduetosmallamountofthecryoconiteonthe
Surface．

W01

As comparedwith aninlandglacier of Alaska，Gulkana glacier，the surface albedois significantly

WO2

MAI

Gulkana

Sjte

Fig．5 Totalcellvolumebiomassofthethreestudiedsites
OnWorthingtonandMatanuskaGlaciers，Showingwiththat of aninland glacier（Gulkana Glacier）in Alaska（Takeuchi，2001d）．Errorbar＝Standarddeviation．

higherin those studied maritime glaciers（Fig．7）．
Accordingtothereportontheinlandglacier（Takeu−
Chi，2002a），themeansurfacealbedoisO．32intheicearea，Whichis significantlylower than that of themaritime glaciersin this study（0．53：mean Of the3Sampling sites）．A statisticalanalysis（one−Way

ANOVA）showssignificantdifferenceofthe surface

Zfi

BulletinofGlaciologicalResearch

Thesmallerorganicmattercontentofcryoconiteon
themaritimeglaciersmaybeduetothesmalleralgal
productionontheglaciers．
Asthecryoconiteisformedbybiologicalactivity

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・

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assuggestedbypreviousstudies（e．g．Takeuchietal、，
2001b），the relation of albedo，CryOCOnite，and algal

一
∴︸
＼
．︑
い．

biomassin Fig．7seems toindicate that the smaller
algal production causes the smaller amount of
CryOCOnite，andthenthesurfacealbedobecamehigher
Onthemaritimeglaciers．Thesnowalgalactivityon
theglacialsurfaceusuallydependsonnutrient，SOlar

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data are not availableinthis study．Althoughtheradiation data are also not available，the radiation
COnditionofthemaritimeglaciercanbeconsideredto

CauSethesma11eralgalactivity．Generally，theclimateJl八騨緋h晦ミむ釣radiationintensity，and melt water disturbance（Yo−Shimura et al．，1997，Takeuchi，2001d）．Thenutrients㍍葛ま遣狩U6艶竃G扇邑転塾閂蔓

Fig．7 Comparison of surface albedo（a），CryOCOnite
amount（b），andalgalbiomass（c）betweenthemaritime
glaciers（inthisstudy）andaninlandglacierinAlaska（Takeuchi，2001d；2002a）．Error bar＝Standard devia−
tion．

COnditionofthemaritimemountainregiontendstobe
Cloudy as compared to the in1and region because
clouds canfrequently formin this reglOn due to alarge amount of water vapor came from the ocean（theGulf of Alaska）．For example，the mean annual

precipitationinValdez City，Whichislocated25km
WeStfromWorthingtonGlacier，is1584mmofwateramountofcryoconiteissmallerinthemaritimegla−

equivalent（StretenandWendler，1968）．Thisislarger
thanthatonGulkanaGlacier（1013mm，1968−98mean，
U．S．GeologicalSurvey），SuggeStingcloudycondition

CryOCOnitein theice areais23g mJ20n theinlandglacier，Whichis approximately6timeslarger than

reduce the solar radiation on theglacier surface，
COnSequently photosynthesis of snow algae would

surface albedo and amount of cryoconite on the ice
Surface differed betweenin1and and maritimegla−
Ciers．The smaller amount of cryoconiteislikely to
CauSehigheralbedoonthemaritimeglaciers．
The biologicalactivityis alsolikely to differ
between the maritime and in1and glaciers．The
Organicmattercontentinthecryoconiteissmallerin
themaritimeglaciersthanthatoftheinlandglacier．
The organic matter content on theinland glacieris

thesmalleralgalbiomassonthemaritimeglaciers．
Thephysicalconditionoftheglaciers，eSpeCia11y
ablationoftheglacialsurface，ismorelikelytocause
thedifferencesofbiologicalactivityandalsoamountOf cryoconite between the maritime andinland gla−
Ciers．Themaritimeglacierischaracterizedbyalarge
amount of annual precipitation due to water vapor
COmlng from the ocean．Thelarge amount of snow
accumulation enables the maritime glaciers to flow

maritime glaciers．The algalcommunities of both
maritimeandinlandglaciersweredominatedbysame

lowerelevation，theablationofglaciersurfacewould
be greaterin the maritime glaciers．According toalbedoamongtheglaciers（varianceratio（F）＝31．37，
probability（P）＝0．000＜0．05）．Furthermore，theCiers（Fig．7）thantheinlandglacier．Theamountof On maritime glaciers．The cloudy condition wouldthat on the maritime glaciers（3．8g mJ2）．Thus，the becomeless active．Thus，the radiation might cause

downlower elevation．For example，terminus eleva・7．1％（Takeuchi，2002a），Whichislargerthanthat onthebothofmaritimeglaciers（6．1％forWorthington， tionsofWorthingtonandMatanuskaGlaciers（mari−
2．8％forMatanuskaGlaciers）．Thetotalcellvolume time）are820and500ma．s．1．，reSpeCtively，Whilethat
OfGulkanaGlacier（inland）is1220ma．s．1．．Hence，thebiomass of thein1and glaciersis also smallerin themaritimeglaciers（Figs．4and6）．Thebiomassonthe altitude of the studied surface differed between theglaciers．The elevation of the studied sites on theinlandglacieris O．52mL m￣2as a mean（Takeuchi，
2001d），Whichis13foldlargerthanthatofthemari− inlandglacieris12701585m a．s．1．，Whichis muchhigherthanthestudiedsitesonthemaritimeglaciers
timeglaciers（0．039mLm￣2）．Onthe otherhand，the（5001110ma．s．1．）．Sinceairtemperatureishigherin
COmmunitystructureissimilarbetweentheinlandand

threespeciesofgreenalgae（Fig．6）．Thissuggeststhat

thecommunityconsistingofthethreegreenalgaeis

COmmOn StruCture On both maritime andinland gla・

ciersin Alaska．The smaller algalbiomass on themaritimeglacierssuggeststhatthesnowalgaeonthe
glaciersarelessactivecomparedtotheinlandglacier．

Summer ablation measurement on the maritime andinlandglaciers，theiceablationonWorthingtonGla−

Cier，70mmdayrlistwofoldlargerthan29mmdayql

On Gulkana Glacier（Mayo and Pさw6，1963；Streten
andWendler，1968）．Astheresultoflargeablationon

themaritimeglaciers，alargeamountofmeltwateris

27

Takeuchiet al．

1ikelytoflowonthebare−icesurfaceoftheglaciers．

region，NepalHimalaya．Snow and Glacier Hydrology（Proceeding of the Kathumandu Symposium，November
1992）IAHS Publ．218，309−316．
Kol，E．（1942）：ThesnowandicealgaeofAlaska．Smithsonian
MiscellaneousCollections，101，ト36．
On theice surface of the maritime glacier．Thus，
Mayo，L．R．，and Pさwe，T．L（1963）：Ablation and net total
radiation，Gulkana Glacier，Alaska，Chapter43inIce and1arger ablation on the maritime glaciers may be
SnOWLProperties，prOCeSSeS，and application，Conference，
responsible for the smaller amount of algae andMassachusettsInstituteofTechnology，1962，Proceedings：
CryOCOnite，COnSequently the surface albedo on the
Cambridge，Mass．，M．I．T．Press，633−643．
maritimeglacierscanbeashighasthecleanglacial
Paterson W．S．B．（1994）：The physics of glaciers3rd ed．，
surface．
0Ⅹford，EIsevier，480p．
Streten，N．A．and Wendler，G．（1968）：The midsummer heat
Sincethedatadiscussedinthispapercoveronly
balance of an Alaskan maritime glacier．Journalof
threeglaciersinAlaska，thecomparisonbetweenthe
Glaciology，7，43ト440．
maritimeandinlandglaciersmightbelessconvinced．
Takeuchi，N，，Kohshima，S．，Goto．Azuma，K．andKorner，R．
Forfurtherdetaileddiscussion，itisnecessarytouse（2001a）：Biologicalcharacteristicsofdarkcoloredmaterial
moreextensivedataoftheglaciersinAlaska．Remote（cryoconite）onCanadianArcticglaciers（DevonandPenny
icecap），ProceedingoftheMemoirsofNationalInstitutesensing technique would be useful to study surface
OfPolarResearch，SpecialIssue，54，495505．
albedoandcryoconitecontaminantinextensivearea．
Takeuchi，N．，Kohshima，S．and Seko，K．（2001b）：Structure，
Thegeographicaldistributionofthecryoconitewould
formation，darkeningprocessofalbedoreducingmaterial
help to understand formation process of the（cryoconite）onaHimalayanglacier：agranularalgalmat
CryOCOniteanditsrelationtobiologicalactivity．
growing on the glacier．Arctic，Antarctic，and Alpine
Research，33，115−122．
Takeuchi，N．，Kohshima，S．，Shiraiwa，T．and Kubota，Acknowledgments（2001c）：Characteristicsofcryoconite（surfacedust ongla−
Ciers）andsurfacealbedoofaPatagonianglacier，Tyndall
We would thank to M．Ikeda and N．Tanaka
Glacier，Southern PatagoniaIcefield，Bulletin of（FrontierObservationalResearchforGlobalChange）
GlaciologicalResearch，18，65−69．
Takeuchi，N．（2001d）：Thealtitudinaldistributionofsnowalgae
for encouragement of this study．We also thank an
On anAlaska glacier（Gulkana Glacierin the Alaska
anonymous reviewer for helpfulcomments．The
Range），HydrologicalProcesses，15，3447−3459．
expense of field work and laboratory analyses was
Takeuchi，N．（2002a）：Surface albedo and characteristics ofSuppOrted by a project of Frontier Observational
CryOCOnite（biogenic surface dust）on an Alaska glacier，Research for GlobalChange（funded by theJapan
Gulkana Glacierin the Alaska Range，Bulletin of
GlaciologicalResearch，19，6370．
MarineScienceandTechnologyCenter）．Thelabora−
Takeuchi，N．（2002b）：Opticalcharacteristics of cryoconite
tory analyses were also supported by Grants−in−Aid（surface dust）on glaciers：the relationship betweenlightforscientificresearch（No．13480154），fromtheMinis−
absorbency andthepropertyoforganic matter contained
try of Education，Science，Sports and Culture，
inthecryoconite，AnnalsofGlaciology，34，409L414．
JapaneseGovernment．
Warren，S．G．and Wiscombe，W．］．（1980）：A modelfor the
SpeCtralalbedo ofsnow．ⅠⅠ．snow containing atmosphericaerosoIs．JournalofAtmosphericScience，37，27342745．
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