Tap chiKHKTMo - Bia chdt, so 31, 712010, tr.23-29
D!A CHAT -
K H O A N GSAN & MOI TRUCiNG (trang 23-74)
DAC DIEM DIA HOA MOI TRlTdNG CUA MOT SO NGUYEN TO KIM LOAI NANG VA LINK DONG TRONG TRAM TICH
VtJNG
B I £ NTIEN YEN - HA COI
BUI QUANG HAT, Trung tdm Tu van vd Cdng nghe Mdi truang-Tdng cue Mdi truong BUI D A N G T H O N G , Trung tdm kiem dinh vd cdng nghe dia chdt
NGUYEN KHAC GIANG, Truong Dgi hgc Md - Dia chat^
NGUYEN VAN HUY. Lien doan bdn do dia chdt mien Bac
Tom tat: Kit qud nghien cim ve dgc diem dia hda mdi trudng ciia mot sd nguyen td kim logi nang vd linh ddng trong cdc trdm tich viing bien Tien Yen-Hd Coi cho thdy trdm tich ven hien (bdi trieu - eira sdng) tgi mot sd khu vuc da bat ddu bi d nhiem. Tuy nhien trdm tich viing bien Tien Yen - Hd Cdi chua cd ddu hieu d nhiem bdi kim logi nang. Cdc kim logi nang Cu, Pb, Zn, As tdn tgi trong trdm tich vdi ham lugng thap han so vdi mire TEL theo Tieu chiidn Canada ve chdt lirang mdi trudng trdm tich (tieu chuan ISQGs do CCME de xiidt nam 1999). Tuy vay ket qud khdo sdt citing cho thdy, trong trdm tich viing bien Tien Yen da xuat hien mot sd diem di thuang vdi hdm lugng tdng cao ciia cdc kim logi ndng cd lien quan den ngudn vat lieu tir cdc cira sdng. Ngoai ra cung thdy cdc di thtrang hdm lucmg kim logi nang tdng cao tap trung tgi khu vuc ddo Cdi Chien vd cira Bd Lang. Tir do cd the thdy nguy ca d nhiem lien quan den cdc hogt ddng sdn xiidt vd ddn sinh dang phdt trien mgnh me trong viing nghien cim.
1. Mo-dau
Vinh Tien Yen - Ha Cdi ed chieu dai khoang 50km bd bien, ed nhieu hdn dao Idn nhd thudc tinh Quang Ninh, thudc viing bien Ddng Bac ciia td qude (hinh 1). Day la viing bien giau tai nguyen thien nhien, cd vi tri chien luge vd ciing quan trgng ddi vdi an ninh qude phdng va phat trien kinh te xa hdi cua dat nude.
Trong nhung nam gan day, kinh te trong viing ven bien Tien Yen-Ha Cdi phat trien kha manh me bao gdm cac ITnh vuc: cdng nghiep, ndng nghiep, giao thdng van tai, du Hch, khai thac khoang san, nudi trdng va danh bat hai san.... . Cac hoat ddng kinh te. xa hdi ndi tren da cd tac ddng tdi mdi trudng khu vuc dac biet la mdi trudng bien: lam mat can bang sinh thai, d nhiem mdi trudng tram tich, bien dang dudng bd. gay xdi Id bd bien, bdi tu san lap ludng lach cira sdng... . Hang nam, mot khdi lugng Idn kim loai nang. cac chat hCru co... dugc cac he thdng sdng, sudi chuyen tai ra bien: bj hda tan trong nude bien va tich tu lai trong tram tich bien. Su phan bd, tap trung. tuong tac gitia cac hgp chat.
cac nguyen td dd se din den nguy co d nhiem
va tac ddng den mdi sinh va eon ngudi. Nham bao ve ngudn tai nguyen thien nhien phong phii trong viing: bai bien, khu bao tdn thien nhien, cdng vien sinh thai, canh quan du lich, nghi dudng..., ddng thdi van dam bao xay dung va duy tri cac cdng trinh qude phdng, kinh te bien, dao, can cu' hau can bien,... can cd nhung nghien cuu co ban cac yeu td tac ddng den mdi trudng lam ca sd cho quy hoach va dinh hudng phat trien ben vung kinh te viing. De sir dung hgp ly tai nguyen bao ve mdi trudng, phat trien ben vu'ng ddi bd ddi hdi can cd su hieu biet sau sac ve dac diem tu nhien cua viing, trong dd cd dac diem dia hda mdi trudng viing nghien cuu lam CO sd khoa hgc cho viec dinh hudng khai thac hgp ly tai nguyen thien nhien, bao ve mdi trudng.
Nhan thu'c dugc tam quan trgng ciia viec nghien ciiu mdi trudng Bien dao. nha nude da dau tu vao cac cdng trinh nghien ciiu cac dieu kien tu nhien ciia cac viing bien dao, trong dd cd viing vjnh Tien Yen-Ha Cdi. Dang chu y hon ca la cac cdng trinh nghien cuu dd cd cdng trinh nghien cu'u "Dac diem dia hda va mdi trudng
dia sinh thai bai trieu cua sdng ven bien khu ; vuc tir Mdng Cai den Dd Son" do Pham Van An chu chi [1] va de tai "Lap ban dd hien trang Dia chat mdi trudng viing bien Hai Phdng- Quang Ninh t> le 1:100.000 va viing bien trgng diem Bach Long VT do Mai Trgng Nhuan va Dao Manh Tiln ehii tri [2], de tai: "Dieu tra danh gia tai nguyen mdi trudng cac vung vinh trgng diem ven bd phuc vu phat trien kinh te-xa hdi va bao ve mdi trudng" do Mai Trgng Nhuanc-
•chu tri [3]. trong dd cd cac tac gia bai ' -^i'^
gia thuc hien. Dac dilm dja hda bai '^'•I'a sdng khu vuc Tien Yen Ha Coi da - gioi thieu trong bai bao cua Ngu>en Thi i auc Anh va nnk [4]. do dd trong khudn khd ciia bai bao na>. chiing tdi se chi gidi thieu khai quat^ dac dilm dia hda ciia cac kim loai nang va mot sd ngUN-en td linh ddng (B. Br. 1) trong tram tich viins vinh Tien Yen-Ha Cdi.
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DaoLoChucSon
Khu vu-c nghien ciru
,^.Lai Tao
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Hinh I. Vi tri khu vuc tien Yen-Ha Cdi tren anh Google 2. Phu-ong phap nghien ciiu va co' s6' du' lieu
De nghien ciru dac diem dia hda mdi trudng tram tich cua khu \'U'c vinh Tien Yen-Ha Cdi chiing tdi da tien hanh cac Id trinh khao sat dgc bd bien de thu thap cac tai lieu ve dia mao. dia chat, thanh phan tram tich... anh hudng den dac diem dia hda cua cac tram tich vung vjnh. Sau dd cac Id trinh khao sat cat ngang qua vinh dugc tien hanh nham thu thap cac sd lieu ve thiiy hai \ an. thu thap cac mau nude va cac mau tram tich da\ bang cac dung cu chuyen biet (dug mau piston, gau xiic chuyen dung hoac
~ dng phdng trgng lire...), cac mau dugc bao quan theo tieu chuan Viet Nam va dugc giri phan tich tai cac co' sd phan tich ciia Trung tam Phan tich thi nghiem Dia chat va Vien Dau khi.
Do Viet Nam chua cd cac tieu chuan qude gia ve mdi trudng tram tich bien nen chiing tdi sir dung mot tieu chuan dang dugc diing kha phd bien tren the gidi la chi ddn tieu clnidn tgm thdi cua trdm tich bien -Interim marine Sediment Quality Guidelines (ISQGs) iiy 1 ^'anada vl :- dgc chat - Environment Canada i a range of toxic substances (CCME 1999) de si. Cac
chi tieu phan tich. dac biet la cac kim loai nang se dugc so sanh vdi cac tieu chuan tren de danh gia mire do d nhiem ciia mdi trudng tram tich.
Sau day chiing tdi se trinh bay chi tiet hon dac diem dia hda cua mot sd nguyen td kirn loai nang va linh ddng cd y nghTa quan trgng ddi vdi mdi trudng trong tram tich vinh Tien Yen-Ha Coi.
3. Dac dilm dja hoa moi trudng cua cac kim loai nang va nguyen to khac trong tram tich
Muc dich ciia viec nghien cuu dia hoa mdi trudng tram tich la phac hga buc tranh phan bd ciia cac nguyen td, dac biet la cac kim loai nang trong tram tich, tir dd xac djnh viing tap trung va d nhiem ciia tram tich. Nhieu nguyen td hoa hgc, dac biet la nhom cac kim loai nang nhu Hg, Cd, Cu, Pb,... khi tdn tai dudi dang cac ion (cation) se rat linh ddng. Chiing de tham nhap vao ca the sinh vat thdng qua con du'dng tieu hoa. sau dd vdi tu each la mot mat xich trong chudi thuc pham, se true tiep hoac gian tiep tac ddng den sire khoe con ngudi.
Trong cac tieu chuan so sanh (ISQGs), cd 9 kim loai dugc dua vao xem xet la B. Fe. V. Pb.
Zn. Cr, As, Ni va Cu, trong dd B, Fe. V khdng ed gidi han cu the ve ham lugng nen se khdng cd CO sd de so sanh xem tram tich viing nghien ciru cd bi d nhiem cac nguyen td nay hay khong.
Khi xem xet bien ddi ham lugng giua cac td phan nhay cam ciia tram tich viing nghien ciru qua bang thdng ke bien ddi ham lugng ciia cac nguyen td, chung tdi thay bien ddi ham lugng cue kim loai nang trong tram tich tuong ddi Idn.
da sd kim loai cd ham lugng bien ddi len tdi hcing chuc lan. Dieu dd the hien d he sd bien thien (V) ham lugng ciia cac nguyen td thirdng
\ ugt qua 50%.
Nhin vao bang he sd tuong quan ham lugng cua cac nguyen td kim loai nang (bang 1).
chiing tdi thay cd mdi quan he thuan kha chat che giua cac nguyen td Cu-Pb, Zn-Sb va dac biet la ba nguyen td B, Br, I trong tram tich bien Ming Tien Yen-Ha Cdi. Tuong quan giua cac cap kim loai khac thudng yeu hoac khdng rd rang (he sd tuong quan thirdng <0,4).
Nhin chung. ket qua phan tich cung cho tha\ cac tram tich viing bien Tien Yen - Ha Cdi
hien vln chua bi d nhiem cac kim loai nang vdi da sd cac mSu phan tich cd ham lugng kim loai nang nhd hon cac chi tieu so sanh (ISQGs) hang chuc, hang tram, tham chi hang ngan lan.
So sanh vdi ket qua nghien ciru thanh phan cac kim loai nang ciia cac tram tich bai trieu- ciia sdng cua khu vuc Tien Yen-Ha Cdi (vi du nhu sdng Ba Che, sdng Tien Yen. sdng Dam Ha...) ciia Nguyin Thi Thuc Anh va nnk (2006) cho thay cd su khac biet ve ham lugng cac kim loai nang trong cac tram tich bai trieu cua sdng va cac tram tich vung vjnh. Cu the trong cac tram tich bai trieu cii'a sdng thudc viing Tien Yen - Ha Cdi da bat dau cd su d nhiem kim loai nang theo muc do khac nhau khi so vdi cac chi tieu ISQGs trong do:
- Tram tich bai trieu cira sdng khu Mui Chiia va khu Dam Ha dugc xem nhu la phdng tu nhien chua cd bieu hien d nhiem nghiem trgng cac nguyen td kim loai nang nhu Cu, Pb.
Zn. Cr, Cd, As.
- Tram tich bai trieu cira sdng khu Ba Che da cd bieu hien d nhiem cac kim loai nang nhu Cu, Pb, Zn, Cr, As do anh hudng ciia cac chat thai tir thugng ngudn luu vuc sdng va ed the do vat lieu thai tir md than Mdng Duong dua tdi.
- Tram tich bai trieu eira sdng khu Ha Cdi da bat dau bj d nhiem nhu Cu, Pb, Cr. As. cd the do anh hudng ciia cac chat thai tir viing Mdng Cai xudi ve.
Nhu vay so vdi tram tich tai cac bai trieu cira sdng, hau het tram tich hien dai tai vung vinh Tien Yen-Ha Cdi van cdn chua bi d nhiem cac kim loai nang khi so sanh vdi cac tieu chuan ISQGs ma chi cd nhu'ng dj thudng ham lugng ciia cac kim loai nang vdi nhung miic do ham lugng khac nhau. Cac di thudng tap trung d gan cac cira sdng trong viing va khu vuc dao Cai Chien va ciia Bd Lang (la nhung khu vuc thuan Igi cho tich tu vat lieu mjn dugc dem tii' trong dat lien ra). Dieu dd cho thay su lien quan rd rang giCra cac di thudng ham lugng na\ vdi ngudn gdc tii' luc dia va nguyen nhan tii' cac hoat ddng dan sinh trong viing vinh.
Sau day chung tdi se trinh bay chi tiet hon dac diem dja hda mdi trudng ciia mot sd nguyen td quan trgng trong tram tich viing nghien ciru.
Bang I. He sd tuong quan giira mot sd ngu\en td trong cac tram tich viing bien Tien Ye 01 ion
Mn Cu Pb Zn Sb As B Br I
Mn Cu
1 1 -0,05 -0.05 ' 1 -0.13
0.08 -0.01 0.32 -0.09 -0.12 -0.09
0,70 0.18 -0.17
0.32 0.36 0.36 0.37
Pb -0,13
0.70
Zn 0.08 0.18 1 ' 0.35 0.35 1 0.23
0,14 0.16 0,15 0,16
0.82 0.25 0.24 -0.23 -0.19
Sb -0.01
0.17 0.23 0.82 1 0.15 0.11 0.09 -0.06
As 0.32 0.32 0.14 0.25 0.15 1 0.001 0.002 0.02
B -0.09
0.36 0.16 -0,24 -0.11 0.001 1 0.98 0,97
Br -0.12
0.36 0.15 -0.23 -0.09 -0.002
0.98 1 0.97
I -0,09
0.37 0,16 -0.19 -0.06 0.02 0,97 0,97 1 3.L Nguyen to Chi (Pb)
Chi la nguyen td hoa hgc sd 82 trong bang tuan hoan cac nguyen td, thudc nhdm chalcophil, nguyen tir lugng 207,21; ti trgng
11.35g/cm\ Cac khoang vat tieu bieu la galenit (PbS). anglesit (PbSOa ), cerussit (PbCO,) Do tinh chat dia hoa ciia Pb, nguyen td nay trong dieu kien bieu sinh (tren mat) lai khdng linh ddng, it tdn tai dudi dang hoa tan trong nude ma chi o dang keo dac thii de bi lang dgng, bdi vav ham lugng Pb trong tu nhien thudng rat thap (<20 ppm hay mg/l). Chi trong cac tram tich vung vinh cd ngudn gdc ehii yeu tir luc dia.
Tai viing bien Tien Yen - Ha Cdi. ham lugng Pb trong trong tram tich dao ddng trong khoang 0.06-2.5.10''%. dat gia tn trung binh 0.55.10"'%. thap hon nhieu so ham lugng trung binh trong tram tich bien ndng Thi gidi (2.10"
'%. Td=0.27) (bang 2). Mau cd ham lugng Pb cao nhat (2.5.10''%) mdi tuong duong vdi ham lugng trung binh cua Pb trong trim tich bien The gidi. kem hon 10 lan so vdi tieu chuan ISQGs cua CCME (32mg/kg). Do vay. trkm tich trong toan khu vuc khdng cd nguy co' d nhiem Pb. Chi phan bd khdng ddng deu trong tram tich (V=79.43%). Pb hinh thanh 5 d\
thirdng dia phuong. trong dd cd 4 di thudng bac 2 va 3 di thirdng bac 3 (hinh 2), vdi muc ham lugng di thudng bac 1 (0,85-1,2. lO'Vo). di thu'cTng bac 2 (1.29-1.70.10'^%). di thudng bac
3 (1.72-2.5.10'-'%). Cac di thudng ciia Pb phan bd d khu vuc: xung quanh khu vuc tram Bien phdng do sau 0-lOm nude (lach di vao cua sdng Dam Ha); eira Bd Lang (0-5in nude), phia Ddng nui Van Hoa (0-5m nude).
3.2. Nguyen td Kent (Zn)
Kem la nguyen td hoa hgc sd 30, thuoc nhdm chalcophil, nguyen tir lugng 65,392; ti trgng 7.133g/em''. Cac khoang vat tieu bieu la sphalerit (ZnS). wurtzit (ZnS), smitsonit (ZnC03). zincit (ZnO). Lugng kem trong nuac dai duong ehii yeu dugc cung cap bdi cac ddng chay til' luc dia dua den.
Ham lugng Zn trong trong tram tich vjnh Tien Yen - Ha Cdi dao ddng trong khoang 0,02- 0,52.10'Vo. dat gia tn trung binh 0,17.10'^%, thSp hon nhieu so ham lugng trung binh trim tich biln ndng Thi gidi (2.10'Vo, Td=0,08) (bang 3). Mau ed ham lugng Zn cao nhat (0,52.10'Vo) cdn thap hon ham lugng trung binh cua chinh nd trong tram tich bien The gidi va thap hon rat nhilu (khoang 2500 lan) so ham lugng quy dinh trong ISQGs ciia CCME do vay khdng cd nguy co 6 nhiem Zn trong mdi trudng tram tich toan viing.
Zn phan bd khdng ddng dIu trong tram tich (V=71.I8%). Zn hinh thanh 5 dj thudng dja phuong. trong dd cd 3 di thudng bac 3 va 4 di thudng bac 2. Vdi cac mire hurr:
(0.25-0.35.10'-''%). bac 2 (0,37-0,4 ,' (0.49-0.52.10'-'%). Nhung dilm <\
phuang cua Zn phan bd d cac khu
lugng: bac 1 10-^%), bac 3 'hudng dia
ira sdng
Dam Ha (0-lOm nude). Nam nui Nha Thd (0-IOm nude), lach Tien Yen (0-5m nude); phia Ddng Nam cira Bd Lang (5-15m nude).
3.3. Nguyen to Dong (Cu)
Cu la nguyen to hoa hgc sd 29, thudc nhdm chalcophil, nguyen tu lugng la 63,5463;
ti trgng la 8.96 g/cm^ Trong dilu kien ngoai sinh. Cu la nguyen td linh ddng va cac ion Cu hoa tan kha nhieu trong nude. Vi du trong nude dai duong ham lugng Cu la 0,00025 mg/l. trong nude sdng sudi la 0.003mg/l. Cac khoang vat tieu bieu ciia ddng la chalcopyrit (CuFeS2). bocnit (CuiFeSa). chalcosil (CU2S).
malachit(Cu3(OH)2 [C03]2)... .
Ket qua nghien ciiu ciia cac tac gia cho thay ham lugng Cu trong trong tram tich viing bien vinh Tien Yen - Ha Cdi dao ddng trong khoang 0.02-l.23.IO"Vo, dat gia trj trung binh 0,29.10'^%, thap hon nhieu so ham lugng trung
binh ciia nd trong tram tich bien ndng The gidi (4.10'^%, Td=0,07) (bang 2) va cung thlp hon nhilu so vdi tieu chuan TEL (Threshold Effects Levels) trong ISQGs cua CCME. Do vax chua dat muc d nhiem Cu trong mdi trudng tram tich biln cua khu vuc Tien Yen-Ha Cdi. Ham lugng Cu phan bd khdng ddng deu trong tram tich (V=70,55%). Cu hinh thanh 5 dj thudng dia phuong vdi muc ham lugng 0,43-1,23.10"%.
trong dd cd 2 di thudng bac 3 va 4 di thudng bac 2. Cac miic ham lugng dj thudng bac 1 (0.43-0,6.10'^%). bac 2 (0,64-0.8.10''%). bac 3 (0,84-1,23.10''%). Cac di thudng ciia Cu phan bd d khu vuc: phia Bac va phia Nam dao Cai Chien (0-5m nude); xung quanh khu vuc tram Bien phdng (cira vao sdng Dam Ha) O-IOm nude; cira Bd Lang (0-1 Om nude). Nhung di thudng ciia Cu phan bd d cac khu vuc tren cdn thap hon muc nguy co' gay d nhiem rat nhieu.
Bang 2. Thong ke bien ddi ham lugng cac td phan nhay cam trong cac tram tich viing bien Tien Yen - Ha Cdi (don vi: 1()~ %)
Ion Mn Cu Pb Zn Sb As Br B
I
Cmax 67 1,23
2,5 0.52 0.048
0,03 5,4 4,3 2,5
Cmin 2 0.02 0.06 0,02 0 0,0096
1 0,8 0,5
Ctb 20,63
0.29 0.55 0,17 0,02 0,01 2.13 1,61 1,14
Cn 16 0.23 0.42 0.13 0,013
0.01 2 1,5
1 S 13.5 0.20 0.43 0,12 0,09 0,01 1.0 0,82 0.48
V (%) 65.57 70.55 79.43 71,18 55.81 41.06 46.94 51,19 42,26
Cn-hS 29,52
0,43 0,85 0,25 0,02 0,02 3,00 2,32 1,48
Cn + 2S 43,05
0,64 1,29 0,37 0,03 0,02 4,00 3,15 1,96
Cn + 3S 56,57
0.84 1,72 0.49 0,04 0,03 500 3,97 2,44
HL TBTG
85 4 2 2 0.14
0,1 0.6 2 0,11
Td 0.24 0,07 0,27 0,08 0.11 0.13 3.55 0.80 10.3
Nguon: Bao cao de lai: "tDleu tra danh gia tai ngu\en moi truong cac vung vinh trong diem \en ba phuc \u phat trien kinh tc-.xii hoi \'a bao ve moi truong. .!/«/' Trong .\hiian. Biii Quang Hal va nnk. 2007"
(ihi ehii: Td = tlam luong trung binh cua ngu\en to trong tram tich viing nghien ciru/Ham lugng trung binh cua ngu>cn 10 trong tram tich bien nong The giai
3.4. Nguy(;n to Arsen (As)
As la nguyen td hoa hgc sd 33. ngu}en tir lugng 74.9216. ti trgng 5,73 g/em3. Ham lugng (ppm) cua As trong vd luc dja la 2. trong da sieu mafic la 0.7, trong gabro basal la 0,7. trona
granit - granodiorit la 3. trong da phien la 13.
dat la 5. nude dai duong la 0.0037 mg/l. trong nude sdng sudi la 0,004mg/l. Cac khoang vat tieu bieu la arsenopyrit (FeAsS). realgar (AsS- hiing hoang), orpiment (AS2S3 - thu hoang).
arsenolit ^ .\s-_0:.)... Ngudn gdc As nhan tao la cac qua trinh nau chay ddng, chi, kem, san xuat thep. ddt rirng. ddng cd, sir dung thudc trir sau diet cd. ddt chat thai va nha may thuy tinh...
Trong dieu kien ngoai sinh. As cd mat trong nude ngam tai nhieu khu yue tren the gidi, trong dd cd Viet Nam. As cd kha nang gay ung thu bieu md da. phe quan. phdi, cac .xoang...
Ham lugng As d mire tdi thieu cd the anh hudng den sire khde eon ngudi theo tieu chuan TEL (Threshold Effects Levels) trong ISQGs cua CCME la 7,2ing/kg (7,2.10"^ ppm hay 0.00072 % trgng lugng mau khd.
Theo ket qua phan tich, ham lugng As trong trong tram tich vjnh Tien Yen - Ha Cdi dao ddng trong khoang 0,096-0,03.10'^ dat gia tri trung binh 0.1.10"^, thap hon nhieu so ham lugng trung binh cua nd vdi tram tich bien ndng Thi gidi (0,I.10'^ Td=0,13) (bang 2). Mau tram tich cd ham lugng Idn nhat (0,03.10'^) cdn nhd hon ham lugng trung binh ciia nd trong tram tich bien ndng The gidi, va nhd han hai lan so vdi chi sd TEL ciia As trong ISQGs ciia CCME, do vav chua dat mire d nhiem trong mdi trudng tram tich. As phan bd khdng ddng deu trong tram tich (V=51.74%). As hinh thanh 8 dj thudng dja phuo'ng, trong dd cd 2 dj thudng bac 3 va 2 dj thudng bac 2. Vdi miic dj thudng bac 1 (0.015-0.02. iVVo). bac 2 (0,021-0,02^5.10"
^%) va bac 3 (0.026-0,03.10'^%). Nhung dj thudng As phan bd d cac khu vuc: phia Bac dao cai Chien (2-10m nude); phia Nam dao Cai Chien 0-5m nude va 10-15m nude; ciia sdng Dam Ha (0-lOm nude); ciia Lan (0-5m nude va 5-10m nude); phia Ddng ciia Lan (10-15m nude).
3.5. Nguyen td bo (B)
Ham lugng B trong tram tich dao ddng trong khoang 0,8-4,3.10"^%), dat gia trj trung binh la 1.61.10"'"%. thap hon ham lugng trung binh trong tram tich bien ndng Thi gidi (2.10' -%) (bang 2). Nhin chung, ham lugng B cd su bien ddi va phan bd khdng ddng deu trong tram tich(V=5l,19%).
Trong tram tich bien Tien Yen-Ha Cdi. B hinh thanh 4 dj thudng dja phuong vdi miic ham lugng (2.32-4.3.10"-'%), trong dd cd 2 di
thudng bac 2 va 1 dilm di thudng bac ' 0'- 45; 4.3.10"-'%). Nhung di thudng cu; an bo chu yeu d: phia Bac va phia Nam cLi ' Chien (2-10m nude); xung quanh tram l n phong (lach vao cua sdng Dam Ha) do sau 0-lOm nude.
3.6. Nguyen to Brom (Br)
Trong tram tich viing bien Tien Yen - Ha Cdi, ham lugng Br dao ddng trong khoang
1-5,4.10"-'%. dat ham lugng trung binh 2.13.10"'%. cao hon ham luong trung binh ciia nd trong tram tich bien the gidi (0,6.10" %), vdi Td= 3,55 (bang 3.2). He sd biln phan cua Br la V=46.94%) cho thay Br phan bd khdng dong dIu trong tram tich. Br hinh thanh 4 dj thudng vdi muc ham lugng (3-5,4.10'''%), trong dd cd I dilm dj thudng bac 3 (5,4.10''%; TY07-45) va 3 di thudng bac 2. Nhung di thudng ciia Br phan bd chu yeu d phia Bac va phia Nam dao cai Chien (2-10m nude); xung quanh tram Bien phdng (lach vao eira sdng Dam Ha) do sau 0- 1 Om nude. Ngoai ra, Br cdn hinh thanh mot so diem dj thudng phan bd rai rac trong viing. Br la nguyen td cd ngudn gdc bien, chiing hinh thanh mot sd dj thudng phan bd d cac khu vuc tren cd le do Br bi biin bien hap thu. Trong nude bien viing nghien ciru Br la nguyen to thieu hut, nhung trong tram tich nd la nguyen to tich luy manh, do vay phan nao ham lugng cua Br bii dap lai su thieu hut trong nude.
3.7. Nguyen td lot (I)
Ham lugng I dao ddng trong khoang 0,5- 2,5.10''%., dat gia trj trung binh la 1,14.10"'%
cao hon ham lugng trung binh ciia nd trong tram tich bien ndng The gidi (0,11.10'^%), vdi Td=10,33. lot phan bd khdng dong dIu trong tram tich bien ciia khu vuc, he sd V=42,26%
(bang 2). lot hinh thanh 4 di thudng vdi miic ham lugng 1,48-2,5.10'Vo, trong dd cd 2 dj thudng bac 3 va 3 dj thudng bac 2. Nhung di thudng lot phan bd cac khu vuc: xung quanh dao Cai Chien; phia Bac va phia Nam tram Bien phdng (lach vao ciia sdng Dam Ha tir 0-IOm nude). Cac dj thudng lot cung tap trung d mire cao trong dai biin set nam d cac do sau khac nhau.
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Hinh 2. Sa do phan bd cac di thudng cua cac td phan trong tram tich tai viing bien Tien Yen-Ha Cdi
4. Ket luan
Ket qua nghien ciru ciia chiing tdi trong thdi gian qua cho thay cho den thdi diem hien tai, khac vdi tram tich cac bai trieu ciia sdng da bat dau bj d nhiem kim loai nang, cac tram tich vjnh Tien Yen - Ha Cdi chua ed dau hieu d nhiem kim loai nang. Cac kim loai nang Cu. Pb.
Zn, As tdn tai trong tram tich vdi ham lugng thap hon so vdi mire TEL theo Tieu chuan Canada ve chat lugng mdi trudng tram tich bien (ISQGs ciia CCME). Tuy vay cung da .xac djnh dugc cac khu vuc dj thudng ham lugng ciia cac kim loai nang vdi cac bac ham lugng khac nhau. Phan bd ciia hau het cac di thudng ham lugng nay cd lien quan den cac ciia sdng trong Ming nghien ciru. Ngoai ra cdn cd mot sd diem cd ham lugng kim loai nang cao tap trung tai khu vuc dao Cai Chien va cua Bd Lang. Ket hgp vdi cac ket qua nghien ciru ciia cac tac gia khac chiing tdi thay hau het cac khu vuc .xay ra nguy CO' d nhiem kim loai nang. cac hgp chat huu CO' deu hinh thanh tai nhung noi dien ra qua trinh hoat ddng nhan sinh manh trong vimg.
Xuat phat tir cac ket qua nghien ciiu tren cd the thay rang chat lugng mdi trudng ludn bi
de dga bdi cac chat gay d nhiem mang ra tir dat lien bdi cac sdng sudi. cac he thdng thoat nude va viing dan cu ven bien ciing vdi cac hoat ddng khai thac sir dung dung dat. Vi vay can cd mot CO che theo ddi va giam sat chat lugng mdi trudng mot each chat che ciia cac cap chinh quyen va ciia cgng ddng dan cu dia phuang de dam bao phat trien kinh te -xa hdi bin vung va mdi trudng trong khu vuc ndi chung va trong viing bien Tien Yen-Ha Cdi ndi rieng ludn giiJ dugc sir trong lanh nhu nd da vd'n cd tir trudc.
TAI LIEU THAIVI KHAO
[I]. Pham Van An, Nguyen Khac Giang va nnk, 2005. Dac diem dja hda va mdi trudng dia sinh thai bai trieu cira sdng ven bien khu vuc tir Mdng Cai den Dd Son. De tai NCCB ma sd 710403. Bd Khoa hgc va Cdng nghe. Ha Ndi.
[2]. Mai Trgng Nhuan, Dao Manh Tien va nnk.
2007. Bao cao de tai "Lap ban dd hien trang dja chat mdi trudng viing bien Hai Phdng - Quang Ninh ti le 1/100.000 va viing bien trgng diem Bach Long Vy ti le 1/50.000". Luu trir Dia chat.
Ha Ndi.
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