T~p chi Khoa hQc va Cong ngh~ bi~n T8 (2008). Sci 2. Tr 42 - 51

DANH GIA BDOC DAU VE NGUON GOC DAU TRAN

o VEN BIEN vitT NAM v Ao NUA DAU NAM zoo?

TRAN DUC TH~NH

Tom tat. Trang thOi gian t1'r th fmg 1 de/1 thang 5 nam 2007. ddu del xudt hi¢n va tr6i dgt vao bb biei1 tren quy m6 lim tgi ddi ven bb va m¢t so' ddo C!la 20 tlnh than h. t1'r Ha Tlnh ve'

phia Nam. Hdu qud Clta ellJf trim ddu rat lim. tnr(Jc m&t Vel ldu dai trong khi ngu6n g&: ddu

fran V(Ln c/ura xac dfnh d1rr;c . Cac gid thief dd c6 de/1 nay ve· ngu6n g6c ddu fran g6m hai

nh6m co bdn. Th/r nhclt Ia t1'r cite giel1g ddu dang kiwi thac hade de/ ng1'rng lu;at d¢ng trong

ho(lc ngoai pham vi lclnh hdi Vi¢r Nam. Tlu'r hai lei fl'r v(in chuyei1 ddu khi vel cac hoat d(Jng

hclng hdi khac phat d6 thdi ca'_y, ho¢c g¢p rai ngn gay rrcln ddu tren bie'n. Ngoai ra. dm m(Jt sa·_-y kie/1 khac.

Tren co sa phdn tich nhirng thong tin , (I( li¢u c6 dl((_lC . rae gid bai viet cho ding ngu6n

goe Clta cldu tran ncly kh6ng phdi do 111¢1 tl11i pham cu th e' gay ra 0' 1116t thoi dieiu cu the'. 111clla

ker qud Clta m(Jr qua rrinh hru tu ddu thdi hclng nclm tren bie'n n'r nhie'u ngu6n g6c . Trang d6.

ddu c(ln t1'r v¢ sinh tau tlwye'n va mr6'c dan tau c16 rhdi rren fuye/1 hang hdi quae f{ va cac v1lng

mr(Jc cdng c6 le Ia ngu6n quan frQng nhci'l . Ddu !hdi da ngu6n g6c d1rQ·c hru tu lhrlnh n'rng v¢t

trong cac Vllllg lf:/p fntll g ngoc/i kiWi Vel tr6i dc_ll tren biei1 lh eo dong hoan flru 6n dinh fl(OIIg d6/.

DQ't £!-Nino keo drli t1'r thang 9 nam 2006 de/1 nay del gciy nhieu d¢ng khi h(iu manh . gay thay d6'i COil fJ'llC tfiUV Vcl/1 bie/1. lam kf16I/1l((JC ngoai khoi Cfu'(a nhieit v¢t e/du tr6i n6i ap Sal biJ va

ddu n6i del xudr hi¢n tren quy m6 l&n .

I. MO DAU

Dau tdm v6'i kh6i ltrqng 16'n bat dau duqc phat hi~n t<;ti kim v!Jc Ciia D<;ti (Quang Nam)

vao dau thang 2 nam 2007. Den dau thang 5 nam 2007, tran dau da xay ra tren quy m6 16'n

d9c ven bO' ttr Ha Tinh tr6 vao phia Nam va 6 m(>t so dao nhu B~ch Long Vy, Cu Lao

Cham, Con Dao, ...

Sim ph~m dau tran vao ba, bai c6 d~ng vet loang, dau nhu, dau c~n von C':IC ho~c

timg, tr6i n6i gan bO' ho~c n~m tren bO', bai, l<in vao trong ca.t. Tren hai nghln tan dau

da duqc cac dta phLWng nh~t, v6't. Tac d(>ng tieu C\JC v6 m6i tmong va kinh te-xa h(>i cua

dqt dau tran rat l6'n, nhi6u khu du ljch, nu6i trong thuy san bj thi~t h<;ti nghiem trQng, trong

khi nguyen nhan dau tran van chua duqc lam r6. Den nay , c6 hai nh6m gia thiet v6 nguon

goc dau tran. Thu nhat la tu cac gieng dau dang khai thac ho~c da ngtrng ho~t d(>ng trong

42

ho~c ngoai ph~m vi Uinh hai Vi~t Nam. Thu hai la tu v~n chuyen dau khf va cac ho~t d¢ng

hang hai khac phat thai ngoai y muon, d6 thai coy ho~c g~p tai n~n gay tran dau ra bien.

Ngoai ra, con m¢t soy kien khac.

Bai viet nay gi6'i thi~u m¢t so ket qua phan tich, danh gia nham trao d6i thong tin,

g6p phan d~nh huang tlm ra nguyen nhan cua dqt tran dau n6i tren.

II. TONG QUAN VE DIEN BIEN DOT TRAN DAU

Tu cuoi thang 1 dau thang 2 nam 2007 hi~n tuqng dau troi d~t vao ba da xuat hi~n

t~i Ha Tinh va Quang Blnh, sau d6 lan r¢ng xuong cac tinh phfa Nam. Dau d~t vao ba t~p trung thanh 3 dqt: Dr;t mrJt tu ngay 28/01 den ngay 10/02/2007, dau d~t vao 7 tinh ven bien

mien Trung tu Ha Tinh tr6' vao den Quang Ngai (Ha Tinh, Quang Blnh, Quang Trt, Thua

Thien-Hue, Da Nang, Quang Nam, Quang Ngai); Dr;t hai tu ngay 09/3 den 15/3/2007, dau

d~t vao tinh Ba Ria-Vilng Tau (ke ca Con Dao) va Tien Giang; Dr;t ba, tu cuoi thang 3, dau

thang 4 den dau thang 5, dau tiep tt,Ic troi d~t vao cac tinh phfa Nam gom Ben Tre, Tra

Vinh, S6c Trang va B~c Lieu; cac tinh mien Trung gom Blnh D~nh, Phu Yen, Khanh Hoa

va d~t tr6' l~i phia Bac den ba bien Ha Tinh va Quang Blnh. D~c bi~t, dau tran da xuat hi~n

6' dao B~ch Long Vy nam giil'a v~nh Bac b¢ thu¢c thanh pho Hai Phong vao giil'a thang

4/2007. Theo tai li~u cua Phong Kiem soat o nhi~m, C~;~c Bao v~ Moi truang (2007), cho

den cuoi dqt dau tran da xuat hi~n 6' 20 tinh thanh ven bien trong ca nu6c v6i t6ng khoi

luqng thu gom duqc la 2.071 tan. Chi rieng 6' phia Bac vi tuyen 16°N, ket qua phan tich

lo~t 26 anh v~ tinh Alos (Nh~t Ban) c6 b¢ cam Palsar (anh Rada) ttr th:ing 12-2006 den 4-

2007 da phat hi~n 14 v~t dau tren 7 anh v6'i t6ng khoi luqng dau u6'c tinh rat l6'n, khoang

21.620-51.400 tan [2].

Tren thgc te, nhil'ng Vl;l tran dau tuong lt! khong r6 nguon goc da tung xuat hi~n nhieu Ian, t~i nhieu noi, nhung thuang guy mo nho. T~i xa Hai Ninh, huy~n Quang Ninh, Quang Blnh, hi~n tl!Q'ng dau VOn Cl;IC tren bO bien da XUat hi¢n vao nam 2000 VOi mtrc d(> con

nhieu han hi¢n nay va trong muoi nam qua, tren vung bien mien Trung da nhieu xuat hi~n

dau tran khong r6 nguon goc vao khoang thang 3-4 hang nam, nhung nam nay la n~ng ne

nhat. Xa han nil'a la cac Vl;l dau tran xuat hi~n vao mua kh6 1994-1995 ba bien Ben Tre va

Tien Giang, vao thang 5-6/1994-1996 t~i Do Son (Hai Phong) va Hai H~u (Nam D~nh),

thang 6/1995 t~i Quang Ninh, HaiPhong va Nam Dinh, thang 4/1997 t~i S6c Trang, thang

511997 t~i Khanh Hoa va thang 6/1997 t~i Da Nang. Trong thai gian 1987-1997 c6 den 89

Vl;l tran dau, trong do CO 42 Vl;l khong r6 nguon goc, thtrong XUat hi~n vao thang 3-4 Ct Trung b¢, th:ing 5-6 6' Bac b¢ [8].

43

III. KHA NANG VE NGUON GOC DAU TRAN

C6 nhilng y kien trao d6i cho rtmg tr~m dau trong cac thang dau nam 2007 do m¢t

thu ph<_tm Cl,l th~ niw d6 can phai truy tlm cho ra . Tuy nhien , theo thong bao cua Cyc Bao

v~ Moi tmong, ket qua phan tich cac mau dau tran vao bo cho thay chung thu¢c ve 6 lo1;1i san pha'm dau khac nhau. Th~t kh6 tin rang, c6 m¢t Vl,l tran dau lan nao d6 l<_ti c6 th~ anh huang den bau bet cac vung bo bi~n cua Vi~t Nam.

Khong ft y kien ban Juan rtmg dau tran Ia tu cac gieng khoan nam ngoai Lanh hai Vi~t Nam, kha nang nhieu nhat La 6 khu vl!c Tay Nam dao Hai Nam (Trung Qu6c) tac

d¢ng den bo bi~n nuac ta do :?mh huang cua gi6 mua Dong Bac. Tlwc ra, kh6 c6 kha nang

nay, vl v6·i d?c di~m hoan luu nuac vinh Bac b¢ vao mua gi6 Dong Bac (hlnh 1), neu c6

tran dau tlr cac gieng dau 6 Tay Nam dito Hai Nam thl cac khu Vl!C ven bo phfa Bac vjnh B~c b¢ phai Lanai chtu h~u qua dau tien. Vai guy m6 tran dau Ian va xa ve phfa B~c den t~n Ha Tinh, tfnh chat dau tran, d~c di~m dong chay vung ven bo Vi~t Nam quanh nam huang tlr B~c xu6ng Nam va l<_ti trung vao mua gi6 Dong Bac, chua c6 du CO' s6 d~ quy

tnich nhi~m chfnh cho cac gieng khoan dau tren cac them luc dja phia Nam Vi~t Nam va

Nam Bi~n Dong. Cling kh6 c6 th~ c6 m¢t lo<_tt cac vy tran dau c6 nguon g6c khac nhau, ke

tiep nhau m¢t each ngau nhien, xay ra nhu la theo m<?t kjch ban da djnh va gay tac d¢ng

den pban lan chieu dai bo bi~n Vi~t Nam.

V~y dau La nguyen nban dfch tlwc cua tran dau? Cau hoi th~t kh6 trii. loi trong dieu ki¢n bi~U biet CUa cbung ta COn h<_tn cbe Va -c0 SO dfr Ji¢u, phLfO'ng ti~n giam Sat, dieu tra,

u·ng ph6 con ngheo nan va l<;tc h~u .

Bi~n Dong n6i chung va bi~n Vi~t Nam n6i rieng la bon chu·a cac lo<;ti dau thai tu

nhieu nguon goc khac nhau: ro ri VO y ho?c c6 chu y tlr cac boat d¢ng khai thac, van

chuy~n dau khf va cac lo<;ti ho<;tt d¢ng tau thuyen tren bi~n , dau tran do cac tai n<;tn tren bi~n va nguon dau thai dua ra tlr ll,IC dta. Nhie~ tai li¢u da n6i den vai tro rat Ian cua nguon dau thai tu cac ho<;tt d¢ng tren tuyen hang hai Qu6c te di qua hai ph~n nuac ta. Theo bao cao de

tai cap Nba nuac KT.03-21 (1991-1995), vung bi~n Tru·ong Sa va tuyen hang hai Qu6c te

c6 ham luqng dau trong nuac bi~n thu¢c lo<_ti cao nhat (d~c bi~t La vao mua he), chi sau

vung phfa Bac vinh Bac b¢ [4]. Ket qua tlr cac tr1;1m trac moi tmong tren bi~n do Cl;lc Bao

v~ Moi tmong quan ly tu nam 1995 den nay deu cho thay ham Lu·qng dau trong nuac bi~n c6 xu huang tang dan tu bo ra khai xa, c6 lien quan den ho<_tt d¢ng tau thuyen tren cac tuyen hang hai.

44

11i6' 108• 110" ~------------------------~a

~--~·=06·------~"·~·------~·~"·----~b

Hinh 1: Mo phong dong chay vtnh Bac b(> v~ mua gi6 Dong Bile (a) va

mua gi6 Tay Nam (b) (Nguon: D(>i dieu tra khao sat Vi¢t-Trung, 1965)

Ho~t d¢ng h~mg hili tu k D¢ Duong qua eo Malacca sang Bitin Dong va len Dong &c A

thu(>c lo:;U nh(>n nh.ip nhat The gi6'i. C6 13 trong so 20 cang container 16'n nhat The gi6'i nam tren

hanh lang tau bitin Singapor-Nh~t &in. Tu vling Malacca len Dong &c A, m6i ngay c6 khofmg 4

tri¢u thllng dau duqc v~n chuy~n tren cac tuyen hang hai Quoc te, chu yeu di qua va ho~c sat qua

hili ph~n Vi~t Nam (hlnh 2). Vung eo bien Malacca cling la noi hay xay ra cac Yl;l tran dau 16'n.

Cling v6'i cac gieng khai thac va ca s& lQC dau phia Nam Bi~n Dong, ho<_lt d(>ng tau bi~n, d~c bi¢t

la ch& dau da lam cho vling ngoai khci Dong Nam B¢ (tu Khanh Hoa den ca Mau) tr& thanh

vling nh<_!y dun vade b! t6n thuong nhat do o nhiem dau tren Bi~n Dong [9].

Hinh 2: V~n tai dau va cac vung de nh<_ly cam-t6n thuang v6'i o nhiem dau 0 vung bien

Dong NamA (Nguon [1])

45

Soo Chin Liew va dong ngbi~p t<;ti Truong Dai hQc Quoc gia Singapor ( 1998) da su

dl;Jng cac anh ve tinh Rada ERS-2 (c6 d(l phan dai lOOm) va RADASAT tham sat cac v~t

dau tren vung Nam Bi~n Dong, v[nh Thai Lan va eo Malacca trong cac nam 1995-1998.

Trong so bon 2500 cimh Chl;Jp, da pbat hi~n OUQ'C t6ng so 7218 vet dau xuat hi~n trong

1399 canh (55 %). C6 nhung v~t dai tren lOOkm. Hau het cac v~t dau nam tren cac tuyen

h~mg Mi. Vung tap trung m~t d<? v~t dau cao nhat nam tren tuyen hang hai Quoc te qua

hai ph~n VietNam, trong h~ to<;t d(l l07°30-ll0°3E va 7°00-ll 11 30N, each ba Vi~t Nam

khoang 100-300km v6i m~t d<? 15-25 v~t /10.000km2 va c6 hai vi:mg loi d<;tt tren 25

v~t/10 .000km2 c6 to<;t d<? tam khoang 107°E-7°00N va 1091130 E-9°00N (hlnh 3).

Tai li~u ti:r nhieu nguon khac nhau da xac dinh duqc m(lt so v~t dau ngoai khoi trong

thai gian dau tran vao ven b0 Vi~t Nam [3] nhu sau:

Vet dau 1 c6 toa d(l di~m xuat phat: 7°4l'lO"N-1081151'52" E va ket thlic

7°28'29"N-l08115l'52"E, di~n tfch khoang 172 km2, duqc phat hi ~ n bang tai li~u vien

tham llic 10.00 gia ngay 26/3/2007 .

Vet dau 2 c6 toa d(l: 09° Ol 'N-110° 04'E, do tau ca KH 96518TS phat hien luc

07 .00 gi0 ngay 27/3/2007 0

Vet dau 3 c6 toa d(l : 09° 57'N-1091154'E, do tau ca QNg 95294 phat hi~n !lie

08 .30 gia ngay 27/3/2007.

. .

Hinh 3: M~t d<? phan b6 cac v~t dau 6 phan phia Nam Bi~n Dong (Nguon [7])

46

Vet dau 4 c6 to~ d¢: 08° 39'N-107° 06'E, chi~u dai khong xac dinh duqc, r¢ng

khoimg 01 hai ly, do tau ca BY 4429 phat hi~n luc 10.00 gia ngay 25/3/2007 .

- Vet dau 5 c6 to~ d¢: 08° 20'7"N-109°13'50"E, do tau ca BTH 98974 phat hi~n

luc 10.25 gia ngay 24/3/2007.

Vet dau 6 c6 to~ d¢: 1011 21 '08"N-107°38'04"E, do tau VINASHIN PACIFIC

phat hi~n hie 14.20 gia ngay 09/4/2007.

Vj trf cua cac v~t dau neu tren co ban d~u nam trong khung to~ d¢ cua vung t~p

trung m~t d¢ v~t dau cao nhat theo tai li~u 1995-1998 cua Soo Chin Liew va dong nghi~p .

To~ d¢ ma tau danh ca Quang Ngai QNg 95294 TS phat hi~n duqc vet dau loang r¢ng

khoang 4 hai ly, chi~u dai khong r6 vao sang ngay 27 thang 3 t~i to~ d¢ 109°54'E-9°57'N

kha phu hqp v6'i vj trf 16i thU' hai cua vung t~p trung. Gan sat ba Da Nang va Nam mui Ca

Mau con c6 nhung khu vt,rc nh6 d~t 3-5 v~t /10.000km2 va gan sat ba Nha Trang, Phan

Thiet c6 khu VU"C d~t 5-10 vet /1 0.000km2• Trung tam U'ng ph6 s~r co tran dau khu vvc 2

khao sat btmg true thang ngay 02/02/2007 da phat hi~n m¢t so vet dau loang tren bi~n

mi~n Trung c6 vj trf cLing kha phu hqp v6i vi trf xac dinh bang tU" lieu v~ tinh cua cac

chuyen gia Singapor v~ khu t~p trung v~t dau gan bo Da Nang.

Do d~c di~m ho~m lU"u cua cac dong chay theo mua tren Bi~n Dong va st,r tfch luy

hang nam cac san pham dau mo tlr nhieu nguon thai khac nhau, a ngoai khoi vung bi~n

Vi~t Nam da hlnh thanh nen cac vung lU"u W dau v~t, tieu bi~u nhat la ngoai khoi Dong

Nam b¢ [9]. C6 le nguon quan tr9ng nhat Ia dau c~n v~ sinh tau va mr6c dan tau (ballast)

d6 thai tv do tlr cac tau ch6 dau va tau hang tren tuyen hang hai Quoc te di qua hai ph~n va

a vung nU"6c gan ciing Vi~t Nam tru6c khi vao d.ng lam hang. Dau c~n de ket v6n t~o

thanh Cl;IC, tang troi n6i va h~n che dU"Q'c qua trlnh nhi1 wong hoa trong moi twang nH6'c

bi~n . V6'i vi~c d6 thai nay, cac chu tilu tiet ki~m dU"Q'C khoan kinh phi va thai gian dang k~

cho vi~c xu ly nu6'c thai c6 dau khi vao d.ng Uun h~mg, trong khi den nay chU"a c6 cac ho~t

d(>ng thU"Ong xuyen ki~m tra, giam Sat va Xlr ph~t doi v6i vi~c d6 thai dau phi phap tren

vung bi~n nu6c ta.

0 vung bi~n ngoai khoi Vi~t Nam, v~ mua gi6 Tay Nam dong chay t~o nen hoan luu

ngU"Q'c chi~u kim dong ho (hlnh 4b), v~n chuy~n dau troi n6i tv ngoai khoi Dong Nam b¢

len phfa Bac va tap trung a ngoai khoi Trung Trung b¢. Vao mua gi6 Dong Bac, xuat hi~n

hoan lU"u dong chay theo chieu kim dong ho a gan ven ba (hlnh 4a) ,dU"a dau troi n6i tra ve

ngoai khoi Dong Nam b¢. Trong di~u ki~n khi h~u - thuy van 6n dinh, cac hoan luu nay it

c6 anh hH6ng trvc tiep vao d6i sat bo. T~i vung ngoai khoi, chi c6 dong hoan luu kha 6n

djnh va dong chay gi6 m6'i c6 tac d¢ng v~n chuy~n dau troi n6i . Cac tac d¢ng cua dong

thuy tri~u thu~n nghjch va dao d¢ng song khong c6 vai tro dang k~ trong qua trlnh v~n

47

chuyen nay. Yao nam co bien d¢ng khi h~u Ion, hoan luu ven ba mang thea dau troi n6i co

kha nang di chuy~n vao sat ba, Hin vao doi dong ven nuoc nang. Noi day song va va song

XO ba CO tac dt.mg di chuyen ngang dau thai tr6i n6i vao ba bai, con song phan X(_! t(_!O ra

dong di chuyen cac v~t li~u dau vang ho~c v6n Cl,lC, tang dQC ba. T<;ti day, cung dong chay

trieu thu~n ngh!ch, cac thanh phan dong du nhu dong gi6, dong song, .. . t<;to nen dong t6ng

hqp sat ba co kha nang v~n chuyen v~t li~u dau tr~m rat Ion. Giao d¢ng mlJC nuoc tri~u 6 vung bai ng~p phoi c<;tn trong ngay cling g6p phan quan tr9ng trong chuyen d!ch dau troi n6i vao ba, bai khi tri~u len.

Hlnh 4: Mo phong dong chay ngoai khai Bi~n Dong

v~ mua gi6 Dong Bac (a) va mua gi6 Tay Nam (b).

(Ngucin: ttp://www.traccorg.my/Borneowast/WEATHER/CURRENTS.htm I)

Nhfrng nam xay ra hi~n tuqng ENSO, thuang co nhieu d¢ng khi h~u Ion va cau true

thuy van tren bi~n c6 th~ bien d6i bat thuong. Vao nam El-Nino 1997-1998, bang phan

tfch anh vien tham mau nuoc OCTS ch1,1p tu v~ tinh ADEOS, cac chuyen gia Nh~t Ban [1]

da xac d!nh duqc dong hai luu am Kuoshio khi qua vung bien phfa Nam Nh~t Ban da d!ch

chuyen len phfa Bac voi khoang each rat l6n, tren ba Vl d¢. El-Nino xuat hi~n tlr thang 9

nam 2006 va van dang tiep tl;lC, CO the da va dang gay ra nhfrng nhieu d<)ng ve khf h~u,

nhfrng bien d¢ng Ion v~ .s.au true thuy van tren Bien Dong, lam cho khoi nuoc ngoai khoi

mang thea dau troi n6i ap sat bo. Ngoai tac d¢ng gi6 mua, vao nam c6 El-Nino, gi6 tu bien

th6i VaO dat li~n CO th~ m<;tnh han do tang chenh l~ch khf ap gifra vung bi~n Va l1,1c d!a Va

d6 cling la nguyen nhan g6p phan lam d<;tt dau troi n6i tlr cac vung tfch luy ngoai khai vao

ba. Tuy nhien, nh~n d!nh nay can phai duqc kiem d!nh bang mo hlnh tinh.

48

IV. KET LU~N

Ngu6n goc dftu tran dang xuat hi~n a nhieu nai d9c ba bi~n Vi~t Nam hi~n nay c6 le

kh6ng phai do m(>t thlt ph<;tm Cl,i the gay ra 0 m(>t thai diem Cl,i the, rna la ket qua CUa m(>t

qua trlnh luu tl;l dau thai h~mg nam tren bi~n ttr nhieu ngu6n goc. Trong do, dau c~n tll' v~

sinh tau thuy~n va nl1<5'c dan tau d6 thai tren tuyen hang hai Quoc te va vung nt1<S'c tmoc khi

viw cang lam hang co le la ngu6n quan tr9ng nhat. Dau thai da ngu6n goc duqc l11U tl;l

th1mh tung v~t trong de vung t~p trung ngoai khai va tr6i d;:tt tren bien theo dong ho~m luu

6n d!nh wang doi. Vao nhfrng nam El-Nino co nhieu d(>ng khf h~u m;:tnh nhu dang xay ra,

cau true thuy van bien d(>ng, khoi nuoc ngoai khai chua nhi~u dau tr6i n6i co th~ ap sat va

tran vao bo do tac d(>ng cua song, gio, thuy tri~u trong dai dong ven va song vo. Vao mua

gi6 Tay Nam, dau tran c6 kha nang lan sau len phfa Bile vjnh Bile b¢.

Voi dqt tran dau vao ni'ra dau nam 2007, van d~ quan tr9ng nhat c6 le khong phai la

di tlm thu ph<;tm C ~l th~ cho dqt dau tran, rna phai di tlm nguyen nhan h~ thong, t~p trung

tham sat phat hi~n cac mang, v~t dau tr6i, chu d(>ng phong chong, Slr ly dau tran vao bo.

Tru6'c mat, can t~p trung nghien CUll phat hi~n va danh gia de vung luu tl;l dftu thai n6i

tren bi~n. theo d6i d¢ng thai di chuytin cua chung d~ lam tot c6ng tac dl,f bao dau tr6i d<;tt

vao ba. Oic tu li~u anh v~ tinh mau nuoc va v~ tinh Rada, cac chuyen tham sat bang trl,fc

thang va tau bi~n la rat can thiet cho cong tac nay . Trong thai gian t6'i, can het sue tang

CIJ'Ong c6ng tac ki~m tra, giam Sat Va Xlr ph<;tt doi VOi cac hanh d(>ng d6 thai dau phi phap

tren tuyen hang hai Quoc te qua lanh hili va de vung nu6'c cang nham giam thi~u va ngfm

ch~n tlnh tr~ng nhu da xay ra.

T AI Lli):U TRAM KHAO CHINH

1. Denzo Inagake and Sei-Ichi Saitoh, 1998. Description of the Oceanographic

Condition of Sanriku, Northwestern Pacific, and Its Relation to Spring Bloom

Detected by the Ocean Color and Temperature Scanner (OCTS) Images. Journal of

Oceanography, Vol. 54, pp. 4 79 to 494.

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INITIAL ESTIMATION ON THE CAUSE OF SPILLED OIL

IN THE VIETNAMESE COASTAL ZONE IN THE FIRST HALF OF 2007 YEAR

TRAN DUC THANH

Summary: From January to May 2007, the floating oil attached the coastal areas and

some islands of 20 coastal provinces in large scale, from Ha Tinh to the sollfh . The

consequences of this event are heavy for forthcoming and long time. meanwhile the cause of

spilled oil has been not determined. The existing suppositions can be included into two main

groups: Firstly. the causes have been from offshore production sites working or stopping

inside or outside of Vietnamese Sea, secondly. the causes are from oil transportation or other navigation activities which purposefully or inpurposefully have dumped oil on th eir rowes. or

shipping accidents on th e sea. Beside. there are some different opinions, but little persuasion.

Based on th e analysis of existing information and data. the author of this paper

indicates that rhe cause of the event has been not from any concrete perpetrator at any

concrete moment. but ji"om the annually accumulative consequences of was:ed oil into the sea

from many different sources . From them, the oil wasres and ballast ji:om shipping on the

international navigatio11 routes or in harbor waters have been th e sources of most importance.

The wasred oil of multi-sources has been being accunllllarei:l i111o rit e slicks concentrating in

the derer111ined offshore waters , and floating on the sea after rit e relatively stable currents hy

seasons. The phenomena of £ !-Nino lasting from September of last year to presenT has made

the cli111atic turbulence and changed in hydrological structure of sea . So that. th e offshore

waters bearing oil slicks has run to coasts and floated oil has been appeared in the large scale.

Ngay nh~n blli: 16 - 11 - 2007 Dja chi: Vi¢n Tai nguyen va Moi tnrang bi~n Ngtl'iti nlz~n xet: PGS. TS. Nguy~n Om H6i

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