HUI n^hi Khaa ^^'.^_y^'' Co"g nt.'Ac' bien loan C/IHK Itjn iim- y
NGIJYKN NHAN VA DIEU KIEN THANH TAO CAC N G A N HAM ECU QUANII CAC DAO DA VOI 6 VINH IIA LONG
N{iuvcn Thanh SOTI , Nguyen l l u u CiJ- , Dinh Van Huy "
1 -1 Idi Dja ly Hdi Phdng; 246 Dd Ndng. I lai Phdng F-niaii: thanhson 1951 ^yahoo.com.vn
2-Vicn Tai nguyen & Mdi trudng bicn; 246 Da Nang. I ldi Phdng Email: imcrvn'c? imer.ac.vn
Tom tat:
Tren ccr sir kel epiu cdc cbuyen khdo .sdl vimg Cdi Bd-Ila Long vdo cdc ndm 2{)0''-20l0 ciia I'len Tdi nguycin & Mdi trudng bien khi thuc hien Die dn si) 14.
"Diiu Ira ca bdn vd ddnh gid ldi nguyen vi the, ky quan sinh ihdi, dia chul vimg bien vd cdc ddo I'lel Nam ", ke}l hirp vdi viee long hc/p cdc ket qud n^hiOn cim Iruve ildy a I 'A' vd ihe guri. cdc tdc gid dua ra mgi sd nhdn dinh ve nguyen nhdn vd dieu kien thdnh lao cdc ngdn hdm ech quanh cdc ddo dd vdi a vinh lla Long, nlur sau:
(I) Qud trmh dn mdn sinh hod ciia nuirc hien Id nguyen nhdn chinh luo nen CC'IC ngdn hum ech quanh cdc ddo da vdi Irong vinh lla Long
(2). Qud trinh dn mdn sinh hod ndy xdy ru Irong diiiu kiisn thudn lgi Id' - Dd vdi cuu Igo nen cdc duo lu logi khd thudn khiet. chieu ddy he tting Idn.
nhieu khe nirt.
- Luang mua khd phong phu. do dm khdng khi cao.
- Thuy Irieu bien dd hm. dong trieu munh. thudng xiiyHn co su xdo Iron, luu thdny, nucrc
- Khu he ddng vdt ddy da dcing ve ihiinh phdn loin, phong phii ve sd luong cd the, cao ve sinh khoi. nhdt Id Thdn mem llui mdnh vd song tren bdi irieu ran dd; Rong ldo hien vd thuc veil phii du phong phii ve sd Immg cd the, cao ve sinh kiwi. Chimg vim true Hep phd huy ca hoc ddi vin cdc ddo dd vol viui gidn tiL'p cung cdp mdt luang lan khi COJ ihiic ddy qua trinh hod lun xdy ni munh mH.
- Su thay ddi muc bien trong Holocen vd1 cue khodng thiri giun on dmli ttrong ddl du tao dieu kien hinh ihdnh cdc the he ngan bien khdc nhuu
Tmi^hanJDja ly. Dig chdt vd Dui vgi ly Bien
REASONS AND FORMATIONAL CONDITIONS OF NOTCHES URROUNDING LIMESTONE ISLANDS IN THE HA LONG BAY
Nguven Thanh S o n ' . Nguyen Huu Cu ^ Dinh Van Huy ^ Abstract:
Bused on the resuhs from investigations conducted by the Institute ofh4urine Environment and Resources during the years 200S-2Q10 in the framework of the component project N" 14 "Comprehensive investigation and estimation oJ position resources, ecological and geological wonders in marine regions, coasted areas and islands of Vietnam" in the general project on
"Comprehensive investiguticm of murine resources and environment until the year 2010 and a vision for the year 2020" and other.s, the reason for this cun be identified as follows
fl) Biochemical corrosive process by the sea water is ihe muin reason;
(2) Biochemical corrosive process is continuous in favorable condhions thai
- Islands are composed mainly of pure und thick bedded limestone wiih notches und crucks;
- Annuul rainfall and monthly humidity are high,
Tide range is wide wiih high velocity current and well exchanged sea water;
Benthos are abundant and diverse, especially Molluscuns is high in biomass; Seaweed and phytoplankton ure diverse and productive, serving us factors of biochemical corrosion and of supplying carbonic for dissolving limestone.
- Changes in the relutively sea-level in Holocene with puiise periods are facile lo create successive generations of sea-level murks.
M O DAU
Da 48 nam trdi qua, kc tir khi Giao su V.P. Zenkovich [I9j dat van de ve nguyen nhdn thdnh lao eac ngan bicn quanh cdc dao da vdi d vjnh Ha Long (VHL), den nay ehiing la vdn chua cd duge ldi giai mgt each can ke va thdng nhat, dac biet la ve eg che qua trinh hoa tan da vdi trong dicu kicn nhic'l do cao ciia viing nhiet ddi khdng thudn lgi cho vii:e luu giu khi eaebonic eua nude bien. Chiing la cung ehua xac djnh dugc ngudn khi cacbonic nay dugc cung cdp tir ddu, chua lam rd dugc vai trd cu the cua cac yeu td khi hau-thuy hai van nhu che dd mua am, sdng, Ihuy trieu, ddng chay da tac ddng toi qua trinh phd buy bd bien d day nhu the nao, chua chi rd duge anh hudng cua thdnh phan va tinh chat cdc nham ihach giau vdi cau tao nen bd bicn. dae biet la boat ddng sdng ciia sinh vat va sir thay ddi muc bicn trong Holocen.
610 tloi n^lv Khoa hoc va Cong nj-hy hien loan guQc tan ih,,- V
Tren co sd k6t qua cdc ehuydn khao sat thue dja viing Cat Ba-IIa Long vdo eac nam 2007-2010 ciia Vien Tai nguyen va Moi trudng bicn (VTN&MTB) ihuge Vicn Khoa hoe va Cdng nghe Viet Nam (VN) khi thue hicn Du an sd 14: "Dieu tra eo ban vd ddnh gid lai nguyen \'! Ib6. ky quan sinh thdi, dja chdl viing bicn va cac dao VN" thudc "De an ldng ihe ve di6u tra ca ban va quan ly tai nguyen-mdi trudng bicn (TN&MTB) den nam 2010. ldm nhin dem nam 2020"\ k£t hgp vdi viec tdng hgp cdc kel qua nghien ciru trirdc dd\' o \'N \d ircn ih^ gidi. irong Bdo eao nay chiing ldi licp tuc phan lieh, nhan xet ve dieu kien \a nguyen nhdn tbanh lao cac ngdn ham ech quanh eae dao dd vdi trong khu vuc.
I. VE DAC DIEM THACH H O C CAC DA GIAU VOI CAU TAO NEN CAC DAO O VHL
Trong khu \ uc HL ed mat eae he ldng tram lich gidu vdi tudi tii' Devon ldi Pcemi, dii Id He tting Phd Hdn (D3-C1 pb) gdm tram tich cacbonat xen lue nguyen phdn bd rgng rai 0 qudn ddo Cat Ba, ehieu ddy khoang 400-650m; He lang Cdt Bd (C| cb) gdm cdc Irdm Uch eaebonai ngudn gdc sinh vdt va hod hge phd bien rdng rai tren qudn ddo Cat Ba \a khu di san HL, chieu ddy 400-450m: He tdng Quang Hanh (C2-P qh) gdm dd vdi ngudn gdc siiili
\dl va hoa hoc, pban ldp ddy va dang khdi, mau xam, xdm sdng, vi hat hoac dn linh phdn bd chil yt;u d vimg Quang Hanh, Deo But, Cdt Ba va khu di san HL. chiiiu ddy 75()m [12|.
Nhdn xet: Cd 3 he tang trdm tieh nay deu ed ehicu day tuang ddi ldn, Ihdnh phan ihach hpe khd thudn khiel deu Id cdc tram lich chira nbii!'u khoang vat canxit hau bet diic d<ing dn linh, vi hat. it khi bj dolomil hoa, ddng thai cd nhieu khe nirt la dieu kicn ldi LIIO cdc qua Irinh phong hoa, dac bicl id qua trinh rira lua, hoa lan lien quan den su luu thdng nude qua he thdng khe nirt eua da.
IL VE DIEU KIEN KHI HAU-THUY, HAI V.AN 1. Nhiet do va do am khung khf
Nhiet do trung binh nam dao ddng tir 22,5 dCn 23,5"C. Miia ddng: 15,0 den 17.0"C.
Mua he; 28.5 den 29^C. Dd am trung binh nam bi6i doi tir 82 d£n 84%. Do dm trung hinh nam bicn ddi lir 82 den 84%. Thdng 3 va 4 cd do dm eao nhat, trung binh 90 den 91%.
Nhirng thdng cd do am thdp xdy ra tir thdng 10 dc-n thdng 1, trung binh khodng 73 den 77%.
Nhan xet: nhiet do va do am cao tao dicu kicn thuan lgi cho qua trinh phong hod ea hgc vd hod hgc phd buy da gdc.
2. Mua
Mua khd phong phii ea vc lugng va sd ngdy mua. Lugng mua trung binh nhiiiu nam ^ <iO khodng 2.500-3.000iiini va sd ngdy mua 120-150 ngay. Xa bd lue dja, lugng mua ui;im dan. d khu vuc Cat Ba, Iirgng mua trung binh nhiiiu nam la 1.806nim, dao ddng i n " g khodng I 600-2.000mni
Nhan xel: Lugng nude mua vao vjnh khd eao, ciiinig thudng cd nhiet do thap vii -.l) jl 1 thdp, khi hod vao nude bicn lam tang kha nang hoa tan da vdi nhdt la Idp nude tiing mai
Tieu hem Dig ly. Dm cluit vd Dta vdi lv Bien
3. Mdt sd hicn tuong thiri liOt diic hict
Suong mil xudt hicn ehii yeu vao miia dong, Irung binh mdi ihang ed 3-5 ngdy. Thang CO suong niLf nhicu nhat la Ihang 3. Vung xa bd suang mil nhieu ban so vdi ven bd luc dja.
Oiiing Id kha phd bien Hdu het cdc thang irong nam deu ed gidng. Miia be trung binb mdi ihdng cd 11-15 ngay cd gidng. Dac bicl Irong Ibdng 8 hau nhu ngdy ndo cung cd gidng.
Bao vd dp thdp nhiet ddi do bg true liap vdo viing ven bd Quang Ninh ehiem 28% ldn sudt lodn qudc. Trung binh mdi nam {ten 1,5 eon. Neu ke cd cde can bao gian tidp thi trung binh mdi nam cd den 5- 6 con. ihdm ehi cd nam ldi 8-9 con (1964). Bao ihudng gdy mua ldn keo dai. cd khi tdi 6-7 ngay. lugng mua dat tren 200nim.
Nhan xel Cae hien tirgng thai Xik dac bicl lam tang cudng do qua Irinh phong hoa eo hoe. hod bge, ddng thai edn lao dieu kien tdng eudng kha nang phd huy bd va ddy thdng qua cdc yeu td ddng lire nhu sdng va ddng.
Miia mua. luong nude luong ddi ldn tir thugng ngufin dfin vdo 6 sdng Dien Vgng. Trdi.
My. Man, Vu Oai, Yen L;ip va dd vao Ha Long dnh hudng manh tdi chd dp bdi van trong vjnh. Trong pha trieu xudng, do ed su ldng cudng eua ddng nude sdng dd ra, tdc do ddng chay tang Icn 1.5 den 2,0 ldn so vdi tdc do dong trong pha trigu len. Trong ky lii6u kem, thdi gian tneu dang ehi bang 30-50% Ihdi gian trieu riit, thdm ehi cd ngay ehi xual hien ddng chdy mdi chieu tii'vung Cira Luc ra HL vdi van tfic lai co Bai Chdy dal gan 2,0m/s
Nhan xel. Nude tir sdng lam nhat va ha ihdp nhiet do khdi nude ven bd, gdp phdn lao nen nhiing ddng mat do quy md nhd trong vinh. Miia khd, luu lugng cdc sdng gidm manh, ehe do nude irong vjnh chii \cu phu thudc vao thuy iricu.
5. Sdng
Ha Long la vjnh tuong ddi kin, cd nhieu ddo xen ke nhau nen sir anh hudng ciia sdng truyen lir ngoai bien vao khdng ldn va sdng do gid cung it cd dieu kicn phat trien. Miia ddng (tir thdng 11 den thdng 4) sdng hudng Dfing vd Ddng Bac thjnh hanh. Mua he (lir thang 5 den thdng 10) sdng hudng Nam va Ddng Nam thjnh hanh. Do cao sdng trung binh la 1,0m, rieng khu vue Bai Chdy la 0,6ni. Tan sudt lang sdng hoae sdng do cao rat nhd chiciii tren 87%.
Nhan xet: Sdng true tiep mai mdn bd va day, ddng thdi tang do luu thfing nude trong vjnh, nhdl la ldp nude tang mat. Nhung sdng d day nhd, khdng du nang lugng mai mdn tao cac hdm ech sdu, nhat la mat dao khuat sdng.
6. Thuy trieu, dong chay, nhiet do, do muoi va do pH cua nuoc bien
Thuy trieu d VHL thugc che do nhat trieu thuan nhat dien hinh vdi hau het sd ngay trong thang chi cd 1 lan nude ldn va I ldn nude rdng. Trong mdt thdng cd 2 ky trieu cudng vdi do eao mue nude trung binh dat 3,9m \ a 2 ky Irieu kiet vdi do cao muc nude trung binh datl,9iii. Do ldn trieu tren 4ni trong thdi ky nude cudng. Muc nude trung binh dal 2,06m.
HOl nghi Khoa hoc va Cong nghe bien loan giiSc ldn ilui
Ddng chdy trong VHL Id tdng hgp ciia ddng chay sdng, ddng chay gid, ddng mdi do \;i ddng tri£u. Trong dd ddng triSu la ddng thinh hdnh, mang tinh chat thuan nghich, gui ui ddng chdy giam tir mat xudng ddy. Tfic do ddngchay chii y6u phu thuge vdo tiing p!u tri^u. cung nhu ddng chdy sdng theo lung miia, ldc do ddng tri^u xudng thudng eao hoii ddng tridu len tir 1,5 d£n 2 ldn. Nhin chung, ddng chay ven bd bac VHL cd gia iri Uiong ddi thdp, Irung binh chi dat O.lm/s. Rieng tai eo Cira Lue gia Irj trung binh dat kliomig 0,19m/s. Vimg phia Dong \ a Ddng Nam ciia vjnh gia trj ddng chay ldn ihudng dal 0.2- 0,3m/s, Irong khi phia Tay vinh gia trj ddng chay ihudng nhd ban 0.2m/s. Tdc dg dong clia\ cue dai do dugc dgc theo ludng vao edng Cai Lan dat l,34m/s trong pha trieu xiioiig va 0,98m/s trong pha iri^u len. Vao ky trieu eudng tai eo Cira Luc, tdc do trieu trong pha trieu xudng ed the qud 2m/s [31.
Theo phuang thang dirng nhiet dd va do mudi d lang day Ihudng ldn ban tdng mai \ a cd xu hudng lang dan ve phia bien. Miia mua, nhiet dd nude vjnh trung binh dat khoang 28,5"C, do mudi Irung binh tang mat dat khoang 23,02 %o, tdng day dat khoang 27,39%o.
Miia khd, nhiet do nude vinh trung binh dat khoang 20,59''C, do mudi trung binh Idng mat dal khodng 30,8%o, lang ddy dat khoang 31.08%o.
Sfi lieu khao sal thdng 6/1998 cho thdy chi sd pH ciia nude bicn ven bd VHL dao diing trong khoang 7.72 den 8.21. Viing cd gia trj cao nhat la ven bd phia Bac dao Cai Ba. nai nude vjnh ed sir trao ddi tdt vdi nude bicn. Viing cd gia trj thap nhat Id vung Cira Luc, noi CO Idi 6 eon sdng nhd eung cap nude ngot [16].
Nhan xel: Nam 1948, nha Dja chat bien ndi tieng ciia Lien Xd (cu) la M.V. Klcnova da nghien eiiu anh hudng ciia dieu kien nhiet do ldi qua trinh hoa tan da voi ngap man [7j. Bd eho rang d viing nhiet do thap nhu vimg cue qud trinh hda tan da vdi thuan lgi ban. vl nhiet do thap eho phep nude bien giii dugc nhieu khi CO2 ddm bdo cho qua trinh boa tan da vol eua nude bien dugc xay ra theo chieu thudn cua cdng thiic: CaC03+C02+H20 ' ^ Ca(IIC03)2. Trong cac nam 1946, 1948, 1950, 1963 mgt sd cdng trinh nghien ciiu qua trinh hoa Ian dd vdi d bd bien Kaspien, Hdc Hdi, California cho thay qua trinh nay cdn xdy ra d viing dn ddi va can nhiet. Hdi bay gid, hau hcl cac nha Dja ehat bicn deu cho rang qud trinh hod tan da vdi ngap man ehi xay ra d viing cue, dn ddi va can nhiet vi ddy la ede ddi nhiet do thdp va kha thap thuan Igi cho viee luu glD khi CO2. Cdn vimg nhiet ddi nhiet dp cao. mac dii tdc do phan ung tang nhung do khdng luu giD: dugc khi CO2 nen qua trinh hod lan kem. Vi vay. mdt sd nha khoa hgc, kd cd Giao su V.P. Zenkovich cung ngae nhicn vc hien tugng Ihien nhien ky thu xdy ra d VHL. Mdt cau hdi bi 3n la: CO2 d dau ra va nude VllL da lu" giif chiing nhu the nao? Chiing ldi sc dd cap toi van dd ngudn cung CO2 tr phdn sau. Cdn vc vdn dc nhiet do nude bidn, ro rang vao ban dem nhiet dd cd gidm di so vdi ban ngdy. nhdt la tang mat hoac vung bidn ndng da md ra khd nang chira COi. ^li*>
phep nd hod tan nhieu da vdi. Caebonal canxi da bj hoa tan sudt dcni cd le duge kel tua vao ban ngay khi nhiet do tang len. Ddi vdi VHL, nhidu cacbonat canxi kdt tiia da nhanh elidng bj mang ra khdi dia diem hoa tan bdi hoat dgng ciia ddng chay tdng hgp, nia phdn idn Id ddng irieu Tuang lu, cac kdt qua nghien ciru ciia R. Revelle va K.O. Emery [9] d Atoll Bikini cho Ihdy cac qua trinh hod tan vao ban dem chii ydu xay ra trong ddi tiieu gian, ehiing di chuyiin eaebonai canxi bi hoa tan xudng ldi muc sat vdi mue nude tneu
IlJlhiaJ?]^ /ll Dig chut vd Dia \e'il ly Bien
llidp, day la noi bao hod ihudng xuyen va cde da voi ngap dudi nude dang bi hoa tan vdi loc do chdm hoii, hoac hdu nhu khdng bj hod lan
IIL VE HOAT DONG SONG CUA SINH VAT 1. Dong Viit day (DVD)
Kcl qua khdo sal vd DVD (khdng kd Xoang Irang) cua VT&MTB da phdt hicn d VllL CO 545 loai, 115 hg DVD ibude 4 nhdm chinh Id Giun nhieu lo. Than mem. Gidp xac va Da gai. Chi so da dang loai trung binb tir 1,8 den 3.6 C3 cdc ran san hd, chi sd nay cao nhdl dat tdi 3.6; tiep iheo la day mdm dal 3 0 va thdp nhdt la khu vire ven bd Sinh khdi vd mdt do cua DVD irong VHL khdc nhau ihco cac sinh canh. Tai khu vuc nen day mem, khdi lugng (sinh khdi) eiia DVD bidn ddng lir 8.807,4iiig ddn 20.206,5lllg/m^ trung binh 14.300mg/m^ mat do DVD thay ddi tir 170 ddn 370 ca lhd/m^ trung binh dat 293 cd ihc/nr Tai eac ran san hd, khdi lugng eiia DVD bidn ddi lir 297,9mg ldi 16.530mg/kg san hd chc-l. trung binh 7.697,lmg/kg san hd chet; mat do thay ddi tir 8,6 ddn 18,7 cdc ihd/kg sail hd diet, trung binh 14.7 cde Ihd/kg san hd chdt. Q khu vuc ven bd, khdi lugng DVD bicn ddi tir 166.969nig ldi 42l.526mg/ni^, trung binh 283.389,4mg/m^; mdi do thay ddi lir 176 ddn 570 cac Ihd/nr, trung binh la 355,8 cde ihd/ni^ [15].
Nhan xet: Uoal ddng true tiep phd buy bd dd gde eiia cac loai Than mdm Hai mdnh vd da dugc V.N. Nhikilin nghien eiiu d bd bicn Hdc Hai nam 1951. 6 day cd rat nhieu loai Hai manh vd da ddo Id vd eu trii tren be mat da set kcl Mat do dao Id ed noi dat tdi 5.200 16/m2, mat dd cu tru tdi 2,600 ea the /ni2. Do sdu lo due ihudng tu 1 ddn 8-lOciii. Cd lodi Bcirnea kandiu sdng dugc 3 nam va ehieu ddi than dat tdi I2-I5em. Mdi nam lodi ndy cd the bdc di mot ldp dd set kcl ddy 3,5-4cm [8] Nam 1960, K..0. Emery khi nghien euu vimg bien phia Tdy California da phai hicn va khang djnh cac ddng vat bicn chac chan cd tham gia vao su cham trd da vdi tren bd bicn. Ong nhan thay trong dicu kien thuan lgi cae qud trinh sinh hod cd the phd huy cdc da vdi cudng do an mdn khdng he thua kem an mdn CO hge va boa hgc ihuan tuy. Cdc loai sinh vdt khde nhau eu tru d ddi trieu gian da tham gia vao qua trinh an mdn bang each khoan, nao, keo, giat, gam va hoa lan da vdi bang eae dich sinh hpc do chiing tiet ra. Trong sd nay, boat ddng cua eac loai dgng vat Than mem, ma dang kc nhat la eae loai thudc Idp Hai manli vd la dae biet rd ret. Cac loai Giun nhieu to, Bgt bicn, I Idi mien, Nhim bien v v. cung cd the khoan moi da [5].
2. Rong bien
Trong VHL da phdt hicn 139 loai rong bien thugc 4 nganh Rong lam, Rong do, Rong ndu va Rong luc. Trong dd Rong lam cd 17 lodi chiem 12,22%, Rong dd 51 lodi chiem 36,69%, Rong nau 34 lodi chidm 24,46% va Rong lue 37 loai ehiem 26,61%. Ve phdn bd, trong sd 139 lodi ndi tren, ed tdi 126 loai phan bd d viing trieu chiem 90,6%; edn viing dudi trieu cd 33 lodi chiem 9,4% [14],
Nhan xcl: Kel qua nghien cuu ciia K.O. Emery nam 1960 d dai ven bd California cho thay cdc loai rong bien ed lbe cham trd, dao Id vao ban dem tren be mat dd vdi. An mdn sinh hge cung xdy ra vdi eudng do manh khi cdc thdm rong tao hinh thanh tren be mat ldp da vdi phoi ra khi thuy trieu xudng. Nam 1946, Giao su V. P. Zenkovich khi nghien cim dai ven bd phia Ddng ciia bicn Kaspien cung nhan ihay cac loai tao dugc nem li;n bd da
Hoi nghi Khoa hpc va Cong nghe btin loiin ciiak lin.
vdi trong thiri gian sdng bao vdi khdi lugng ldn da phd buy bd da vdi vdi cudng do kha manh [18],
3.ThucMitphudu(TVIM))
Kdt qud nghien ciru cua VFN&MB [1,2] cho ihdy tbanh phdn lodi TVPD d viing biOa ven bd Quang Ninh-Hai Phdng (VBVB QN-llP) rat phong pliii. Da xdc djnh dugc 1S5 loai. 61 giong thudc 4 ngdnh Tao Iuc, Tao lam. Tdo giap ya Khuc tdo. Trong dd nganh Khue tao phong phii han ca. cd 139 lodi thufic 50 gidng chiem 84,24% tdng sd loai TVPD Irong khu vuc Nganh Tao gidp ed 28 lodi thudc 9 gidng chiem 15,12%. Ngdnh 'I'do lam eii 2 lodi Ihudc 1 gifing chidm 1.08%. Ngdnh Tdo luc ed 1 lodi thuge 1 gidng chiem 0,54%
Vc phan bd mat rdng, Ifing sd lugng tc bao vd smb vdt lugng eiia TVPD Irong VBVB QN-IIP cao han so vdi vjnh Bdc Bd Gid In trung binh long luang tc bao VBVB QN-lIP vao khodng 10''-10^ td bdo/ni"'vd sinh vdt lugng dal 200-250iiig/m-'. Tai VllL, dot khao sal vdo thdng 1/1997 cho thdy mac dii khi dd dicu kien thin tiet khdng thuan lgi eho sir phai indn ciia TVPD nhu khfing cd ndng. nhieu suang mil lam giam biie xa mat irdi. han che khd nang quang hap va nluct do nude ludn dudi 20"C nhung sinh khdi TVPD d ddy vdn dat khodng 512-604mg/m\ trung binb dat 546nig/m^. Tdng luang sdn pham long hop dugc irong 1 ngdy cua TVPD (nang suat thd) dat khd cao, trong khoang 61-71mgC/m'.
trung binh 66,6iiigC/m^. Trong do, lugng sdn phdm tich luy Irong co the TVPD md cdc sinh \al bae eao bon cd the su' dung tiep trong chudi thuc an (nang sual tinh) nam tiong khodng 35 - 41mgC/ni"Vngdy. irung binh 37.8mgC/m /ngdy.
Nhan xet: The gidi ihuc vdt ndi chung vd TVPD noi rieng deu sir dung khi eaebonic trong qud trinh quang hgp vdo ban ngay. Ban dem qua trinh quang hgp dimg lai do khdng cd dnh sdng mat trdi va khi cacbonic lai dugc thdi vdo trong nude bicn. Theo chiuig ldi, su da dang vd phong phii cac loai thuc vat bien. dac bicl la cdc Ioai rong tao vd TVPD d day chinh la ngudn cung cap mdt lugng ldn khi eaebonic cho nude bicn, dam bdo cho viec tang eudng do hoa lan cdc da giau vdi edu tao nen bd bicn va cdc ddo trong khu vuc.
IV. SU TIIAY OOl MUC BIEN TUONG DOI TRONG HOLOCEN lYong ky De tir, khu vuc HL va lan can da nhicu ldn bj lam ngap va phai khfi. Cd y ngliTa nhdl dfii vdi sir hinh Ihdnh va phdt tridn bd bidn hicn nay la dgi bicn lien sau bang hd lan eudi. hay cdn ggi la bien lien Flandrian. Bien lien Ircn quy md todn cdu, xuat phdl tir do sau khoang 120iii, bat dau xay ra tir thdi gian each day chirng 17-18 nghin nam. kcl qud phdn lich tufii tuyet ddi bang C'**eac mau Irani tich than biin lagoon hien nam d do cao 0.5iii tren dao Khe Con thudc qudn ddo Cfi Td eho bidt ehiing duge thanh lao vao khoang thdi gian cdch nay chirng 7.520-7.680 nam. Cd le bidn bdt ddu tidn vdo vimg ria ciia khu vuc lla Long vdo thdi gian each nay chimg 8 nghin nam, dat tdi mirc Om vdo thai gian cdch nay chiing 7,2-7,3 nghin nam, dat do cao cue dai 4-6iii vdo thdi gian cdch day 5.6 nghin nam, Bien dirng d mdc nay mgt Ihdi gian Sau dd thi bidn liii, bidn da liii ve vi iri Ihdp ban hicn nay vao thdi gian each day chimg 3-4 nghin nam. Tidp dd bidn lai Uen \d cdn ed mgt vai dao ddng nhd trudc khi trd vd vi Iri hien nay [12]
Nhan xcl: Su thay ddi muc bidn tuang doi irong Holocen d khu vuc Hai Phdng-Quang Ninh xen ke eae Ihdi ky muc bidn dn dinh tuang ddi . Do bien tidn Flandrian (ran ^ :i'^
Tieu han Dig lv, Dig L lieh vd Diu vgt ly Bien
\ung CO dia hinh karst chia cat phirc tap. ben ngodi cd dao Cat Bd ehe chan. nen Irong qua kliir nia> nghin n;im gdn ddv cae net chung \ e ebe dd sdng-tricu Irong VllL khdng khdc bicl nhieu. Dicu kien khi hau tir khodng 7,7 ngan nam trd lai ddy d khu vuc duyen hdi Bae Bfi dd mang linh chdl ndng am gdn gidng hicn nav. nhung vdn cdn mol vdi dao ddng |20|.
Vi \d\'. cdc ihdi ky muc bicn dn dinh luong ddi trong Holocen Id dieu kien tluian lgi eho qud irinh hod lan pha huy mdi khdi luang Idn dd \di lao cdc ham ech sdu khdc vdo suim cde dao. Chan eua cdc ddo da vdi irong VHL ihuimg nam d d d sau 2-5ni \'a 7-lOin, ddi nai dal ldi dd sdu 15-20m. Kcl qud ldn khao sal cua VTN&MTB da phdl hien ede ngdn ham ech d eae do sdu 4-5m \d 1 -1.5m Vc pbia tren. phd bicn cdc ngdn ham ech nam a dd eao 4-6m. 3-3.5iii \'a 1.5-2.5ni tren mue bien trung binh. ehiing hau nhu cd nidi d ldi ca e,ie dao da \di ir khu vue cd che do kien lao nang len Irong I loloccn Nhicu noi ede hdm ech nd\ duac bao ldn rat idi \'a lao nen cdc lbe he ngdn bien khdc nhau ngay trC-n mol \dcli dd.
K I T L U \ N
Qua cdc phan da Irinh bay d ircn. ed the di ldi nhirng ket ludn so bd vc ngu\i:n nlidn \ a dieu kicn ihanh lao cdc ngan ham ech quanh eae dao da vdi d VI11. nhu sau
1- Qud irinh an mdn smh hod ciia nude bien la nguyen nhan ehinh lao nen cdc ngdn hdm ech quanh cdc dao dd \di irong VllL,
2- Qud irinh an mdn sinh hod ciia nude bien ddi \di cdc ddo dd vdi Irong VI IL \u\ la Irong cdc dien kien ihudii lgi cu Ihc Id :
- Dd \di odd> Id loai khd ihuan khiel. ehieu ddy he lang ldn xa nhiiju khe mil.
- Lugng mua khd phong phii. do am khdng khi cao.
- Thu> irieu ed bien do Idn, ddng lrii;u manh. Thudng xuyen cd su \ao Iron, luu thong nude.
- Khu he DVD da dang vc thdnh phdn loal. phong phii \c sd lugng cd the. cao \c sinh khoi. nhdl Id '1 hdn mem Hai mdnh vd sdng ircn bdi trieu ran da; Rong ldo \a TVPD phong pliii \ e sd iugng ea ihC'. eao \ e sinh khdi; Chiing vii'a true tiep phd huy ca hoe ddi vdi cdc ddo dd \di. \ira cung cap nidt lugng ldn khi CO: diuc day qud trinh hod lan xd> ra manh me
- Sir Ihav ddi muc bien Irong Holocen vdi cdc khodng thdi gian dn djnh tuong ddi da lao dicu kicn hinh thanh cdc the he ngan bicn phdn bd d cac do cao va do sau khdc nhau.
De xde dnih chinh xdc vai trd cua tiing yeu id ndi tren tdi su hinb thdnh \d phdl trien cdc ngan ham ech quanh cdc dao da vdi d VHL cdn thiet phdi lien hdnh cdc nghien ciru chi (idl \d do dac dinh hrgng. trong dd dac biet eliii \' cdc thdng sd ve biC'n ninh ngdy. niiia eua yi:u id nhiei dd. do pl I. ham lugng eaebonic, hdm lugng canxi boa lan Irong eac tang nude.
So sdnh \di cdc vimg cd bd da vdi ngdp man khdc iren lbe gidi cd the nit ra quy lual ehung vd khdng djnh nhung gid tri dac huu eiia he thdng ngdn bien quanh cdc ddo da vdi nude la
Hill ii^lii Kliuii hue VCI Cong n^hi hiin loan tjiiuc ttin lln:
TAI L1EUT1I.\M KHAO
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