//(}()ighi Khoa hoc vd Cdng nghe hien loan qudc tdn ihd I D\C DIFM NGUV CO NHIKM VA CAC CIAI PHAP ll.\N CHE NGUV CO O NHIKM CAC HOP CHAT PCBs VA OCPs TAI VUNG BIEN M\ T I I \ M I - \ I.Ml HAI (SOC TRANG) Phnm Thi Nga, Lc Van Diic, Nguyen Duy Du>en Trung tdm Dja chdl va Khoang san bien 125 - Trung Kinh Trung I ina, Cdu Gidy Hd Ndi Email' lidhmtbicnmgu'oigmail.com Tom tat : Trong vdi thdp ky vira qua d nhiem cdc hop chdl hiru ca clo ben virng dd thu hut sir chil y cua nhieu nhd khoa boc triin thU giixi chinh khu ndng tieh liiy sinh hgc munh, ddc linh cao ddi vdi nguiri vd cdc lodi sinh vat ciing nhu tdc ilinig xdu da hge eho phdt irien ben viing vd quy hoach sil dung hgp Iy ldi ngusfin II PHI ONG PHAP PHAN TICH De nghiC'n ciru mirc d nhifim cae hgp ehdi PCBs OCPs tram tieh vimg bien Sdc Trang, ehiing idi da sir dung cdc phuang phdp phdn tich sac ky khdi phd kfit hop vdi sac kV edng kfit dieti lir Mdu tram tieh duge chiet ldn vdi dung dich axeton va dich chicl duge chuyen \ iio pheu chiel chua 100ml hexan \'d 600ml nude rira dd rii'a bang hcxan Sau dd dich chiet dugc cd \'d cbo qua cot nhdi Florisil de lam sach va phdn lach C) giai doan dau lien p.p'-DDli \ a PCBs dugc rira gidi bdng hcxan giai doan Ihir hai rira giai bang hdn ligii 20% dielomclan hcxan \'d ihu duge p.p'-DDD, p,p"-DDT vd cdc ddng phdn \IC\1 Luu huynh dugc loai bang dong boat hda San pham ciia mdi giai doan duge ed rdi bom len may sae ky \'di deleelor cdng ket diC'n Hi (GC-ECD) dfi dinh lugng Gidi ban phdl hicn ciia cdc hgp chat lri;n dao dgng tir 0,001-0,0 Ing/g [2,3,4] Cdc chi lieu phdn lieh tren dugc lien hdnh tai I'lidng Phan lich Trgng difim Qudc gia thugc Vicn Ida hgc Cdng ngbicp tldi nghi Khao hoc vd Cung nghe hien a 111 DAC DIEM VA NGUY C O NHIEM CAC HOP CHAT HlTU CO (I'CliS, OCI'S) TAI VUNG BIEN SOC TIJANG Dac dii;ni phiin bf> cac hop chat PCUs va OCPs tram tich tang mat [1 ] Ham lucmg t6ng PCUs va OCPs dao dong lihoang kha rgng, PCBs: 2,98-8.50ng/g va OCPs: 0,20-0,j0ng/g (bang 1.2) S6 luong h(ip chdt OCPs dugc phat hicn chii yeu tir 3-7 hgp chit: lihu vuc cira" My Thanh (3-7 hgp chat), cira song xa VTnli Hai (4-5 hgp chat), Trong do, s6 luang hop chit PCBs tai khu vuc cira My Thanh va ciia song xa VTnh llai ciing la 15-16 hop chat a) Dac di(;m phan bo cac hop chat Ihu6c trir sau goc clo (OCPs) Sfl lugng cac hgp chSt OCPs co mat trong mau tram tich tang mat kha da dang, voi su CO mat cua'cac hgp chat: a-HClI, y-lICll p-llCH, 6-llCll, p,p DDE, p.p'-DDD p,p'-DDT (bang 1) Trong hgp chat p.p'-DDE co ham lugng chicm uu the (p.p'-DDli 0.15-0.20ng/g);''cac hop chat lai (a-llCll, y-lICII, [J-llCH, 6-UClI p, p'-DDD, p, p'DD T) CO ham lugng nho va dao dgng khoang ND-0,04ng/g (bang 1) Hinl, 1' So vi ti'i cliein mdu chi Ihi ddnh ddu phdn lu vung hien Scjc Trdng Bdng J: Tham so dia hoa mui Irudng cdc hap chdl OCPs (Don vi hdm hrang ng/g N=22 mdu) ngn Cll^l u-lKIl y-lKII P-llCI! 6-IKII p,p'-»ni: p-p'-DDD p.p'-ni) r -fim o< !•'' (•|1M\ 11.01 O.lil O.OI 0,01 0,20 0,01 0,04 0,30 ('lillll ND ND 0,01 0,01 0.15 ND 0,03 0.20 Clh 0,01 0.0! 0,01 0,01 0.18 0.01 0.03 0,26 mT^ ND: nhd hon gidi hgn phdl hien cuu thiet bl phdn tich Tli'u han Dieily DiachcU vd Dia vdt ly Bien b) Diie difim phan bo cac hop chSt PCBs Trong Iram tich ldng mat viing bien Sdc Trang phan ciia PCBs gdm ddng dang eiia nhdm il clo den nhifiu clo: 2,4,4' triclorobipbenyl; 2,2',5,5'-leiraclorobipheiiyl; 2.2'.4.5.5'penlaelorobipbenyl; 2,3,4.4\5 Pentacblorobipbcnyl; 2,2',3,4,5,6'Hexachlorobiphcnyl; 2,2\3.4,4',5 hcxaclorobipbenyl; 2,2',3,4,4',5,5' heptadorobiphcnyl vd ldng 2Cl ldng 3C1, ldng 4C1, tdng 5C1, tdng 6C1, ldng 7C1, long 8CI, ldng 9CI, tdng lOCI Ham lugng tdng PCHs dao ddng khoang 6,56-8.5ng/g, dat gid tri trung binh 7,47ng/g Trong dd, eac hgp chdt chifim chii yfiu man: 2,2',3,4,5,6'Hexachlorobiphenyl; 2.2\3.4.4'.5 hexaelorobiphenyl; 2.2",3.4,4\5,5\ tdng 6CI (bang 2) Bang 2: Thum sd dia hiru mdi truimg cua cdc herp chdl PCBs (Dan VI hum luerng ng/g: N=22 mdu) Hop dial Tliam so " _^_^ Cmax Cmin Ctb 2,4.4 iriclorobiphcny] 0.54 0,20 0.37 2.2 ,5,5 -Ictraclorobiplicnyl 0,38 0,03 0,20 2.2.4.5.5 pcnlacJorobipliL'iivl 0.03 ND 0,01 2,3,4.4 Pcnlaclilorobiphcnvl 0.02 0,02 0,02 2,00 1,59 1,82 4.30 2,41 3.15 2,2",3,4,4",5,5' lieplaclorobipiicnyl 0.16 0,05 0,10 T6ni! 2CI 0.04 0,01 0,02 T6im 3CI 0,54 0.20 0,37 Tons 4CI 0,45 0,07 0,25 Tona SCI 0,16 0,01 0,09 Tiini" 6C1 7,55 4,73 5,93 Tom: 7CI 1,30 0.27 0,62 0.11 Tina SCI 0,29 0,01 Tina 9CI 0,13 0,02 0,06 Tfina lOCI 0,01 ND 0,00 Tina PCB 8,50 6,56 7,47 ND nhd hern giai hgn phdl hien ciia thicd bi phdn lich c) Dye diem phan bo cac hop chat PCBs va OCPs theo chieu sau cgt miiu Trong vimg bien Sde Trang, da lien hdnh thu thdp va phan tieh cae mau ept mau lay lai cira My Thanh vd cira sdng xd VTnh Hai Ket qua cho thay cac hgp chat OCPs va PCBs cd ham lugng ldng dao dgng khodng 2,98-8,50ng/g vd 0,02-0,54ng/g luang mg (bdng 3, 4) Hi'n nghi Khoa hue vd Cong nghe hien lodn e/iidc lein ihd I Bdng Tham s6 dia Iwu mdi trirdng eiiu cdc hap chdl OCPs cdc cgt mdu (Dem vi hum luong- ng'g A'=^22 mdu) S5 kliu Iham CVI mflu Cira M\ lh.iiili Cua stiny Vitili llai ni)S-ll23 (ll-153Lml 1108-1125 1108-1312 (U-ll2cm) 10 mau 111.U1 fmj\ Cmin Clb Cin.i\ fmiii (.111 Cm.i\ Cmin [i-n( II r-iicii p-IKIl &-IH IE p, p-oDi: i) n'-i]i)i) p li'-DDI 0.01 Nl) 0112 0f Ni) 0.1)1 M) Nl) 03 ND 01 0,02 Nl) 0.01 0.01 Nl) 1104 Nl) 02 03 0.01 0,02 02 Nl) 0,1)2 Nl) 0.(11 0112 0.1)1 O.OI 0.02 O.OI 0.38 0.01 0.22 0.37 N!) 0.21 0.16 0.02 NH O.OI 0.0; M) 0.01 U.Dl NI) ().()! 0.05 0.01 0.03 0.04 0.02 0.02 0.U4 O.OI Nl) 003 0,01 O.OI 0.11 0.004 -1 m.^ii tlb 0.02 ND nho hern gidi hgn phdl hii77 cua duet bl phdn tich Bung -I Tham sd dia hda mdi irudng cdc hap chdl PCBs cdc col muu (Dem vi hiim luong ngg, N=22 muu) So hioo cot mail U08-1I23 K h u MIC llOS-1125 1308-13 12 Ctia M i lianh C h i c u sau cot m.iu 0-153cm So Iirona man C u a song v,i V i n h I n 0-80cm 10 mau 0-112cm mau man Tham so l a p chat Cmax Cmin Ctb Cmax Cmin Ctb Cmax Cmin Clb 2.4.4 t r i c l ( ] r o b i p b c n v l 0,77 0,14 0.52 0.58 0.21 0,40 0.59 0,20 0.56 0,44 0,10 0.29 1.01 0,04 0,24 0,32 0,03 0,14 2.2 4.5.5 p c n t a c l o r o b i p h c i n 2,2 ,5,5 -tctraclort)biphcnvl 0.11 ND 0.04 0.07 ND 0.01 0,04 ND 0,02 2.3.4,4 ,5 P e n t a c h l o i o b i p h c n \ 0,03 0,01 0,01 0,04 0,01 0,02 0,02 0.01 0.02 •'.^'.3,4,5.6'-Hc\aclilorobiplicn\l 2,34 0.41 1.07 2,07 1,05 1,48 1,87 0,71 1.37 2.^ ,3.4,4 ,5 h c \ a c i u r o b i p l i c n \ 2,41 0.95 1.66 4,30 1,26 2,05 2.75 0,84 1.61 0,26 0.08 0.13 0,26 0,07 0,16 0.20 0,05 11 T o n a 2CI 0,09 0.01 0,03 0.11 0,01 0.06 0.08 0.04 0.07 T6iig t 0,78 0,14 0,52 0.58 0,21 0,41 0.59 0,20 Tr36 T61IH 4CI 0.47 0,12 0,37 1.55 0,09 0,46 0.36 0,07 0.16 Toil.a SCI 0.49 0.03 0,15 0.78 0,01 0.19 0,29 0,11 0.19 T n a 6CI 4.73 1.96 3,54 7,55 2,69 4.10 5.51 1,30 0,13 0,31 0.34 0,09 0,26 0,30 2,11 0,20 3,54 T6iig7CI T o n a SCI 0,13 0,01 0,04 0.33 0,03 0,17 0.29 0,05 0,19 rdna t 0,13 0,01 0.06 0.06 0,01 0,04 0."i 0.04 0.05 T o n g lOCl 0,01 ND 0,003 0,03 ND 0,01 0,01 ND 0.0112 l o n g I'C 15 7,34 2,98 4,92 8.50 4,12 5,71 6,56 3.86 4.82 0,24 ND iilio liuii gidi han plidl h,S,i cia IhiSl bi phdi, lich Trong col mau B08-1I23 (0-153ciTt) lay tai khu vuc ciia My Thanh, ham lugng long OCPs CO gia Iri 0,29ng/g tram tich tang mat (0-lOcm), giam xu6ng gia tri cue lieu tr sau IO-20cni (0,09ng/g) sau tang cao ttii giii iri cue dai: 0,47ng/g li sau tti X''92cm va giam xuong ti cac sau tiep Ihco (I09-I53cm): 0,21ng/g Trong do, ham lirirng long PCBs dat gia Iri circ dai kVp tram lich ting mat (0-lOcm): 7.34ng'g giam - Tieu ban Diu ly, Dig chdl vd Dta vdt ly Bten ddn Ihco sau cdt mdu vd dat gia tri cue ticu ddd sdu (125-140em): 3,51ng/g(hinh 2) Ifmh 2' Dd thi hien thien hum Immg hap chdl OCPs vd PCBs ciia col mdu B08-I123 ldy fgi khu vuc ciru My Thgnh Trong col mdu B08-1125 (0-80cm) ldy d khu virc cira My Thanh, ham luong tfing OCl*.s cd gid iri 0.27ng/g irong tram tich tang mat (0-lOeni), sau dd gidm xudng cue lieu' 0,04ng/g d sau 10-20cm, ihco chieu sdu cgt mdu (20-50cni) OCPs cd ham lugng lang ddn: 0,34ng/g-0,40ng/g, sau dd gidm xuong d sdu 50-70cni vd dat gia tri cue dai d dg sdu 70-80cm: 0.44ng/g Tuy nhien, PCBs cd ham lugng tdng dat gia trj cue dai tidm li'cli tang mat (0-IOcni): 8,50ng/g, dat gia tri cue lieu d dd sdu Idn nhat (70-80cm): 4,12ng/g(liinh3) ////;/) Di) ihi bien thien hdm luang hgp chdt OCPs vd PCBs ciia cot mdu B08-1125 lay lui khu vuc ciea My Thanh DOCPs n PCBs 50-72 90 112 u tilt mUa ((.ml Hinh 4- Dd thi bien thien hdm lugng hgjr chdt OCPs vd PCBs ciia col mdu BOS- 1312 lay lgi khu vuc \ 7nh Lldi Ildl nghi Khua hoc vd Cdng nghe bien lodn ciuoc le'in ihu Ddi vdi cdt mau thu dugc tai khu vuc cua sdng xa VTnh Hdi B08-1312(0-112em) hdm lugng tdng OCPs ed gia tri 0,21 ng/g d sau 0-20em, gidm xudng tdi gia tri cue lidu d dd sau 50-72em (0,05ng/g) sau dd tang cao dat gid in cue dai d sau 90-112cni (0,22ng/g) Trong dd ham lugng tdng PCBs dat gia tri cue dai (6,56ng/g) trdm tich tdng mai d dd sdu 0-20cm, sau dd gidm dan theo chicu sau edt mdu va dat gia tri cue tieu d sdn 90-112em (3,86ng/g)(hinh4) Qua dae diem phdn bd cdc hgp chdt PCBs va OCPs theo khdng gian vd thdi gian cd Ux" dua nhan dinh rang cac hoat ddng lau ihuyen va edng nghiep \'iing dang dicn i:i manh me khu vuc ddn den viec tang cao hdm lugng tdng PCBs ldp Irdm licli tang mat Trong dd viec sir dung cae hgp chat OCPs ed ngudn gdc tir cdc hgp ch.u thudc bao vc Ihuc vat da dicn manh mc tir cae Ihdp ky trude, sau dd gidm dan va hieu dang cd xu hudng tang len Du bao nguy co" o nhiem moi tru'ong tram tich bd'i cac hop chat PCIis s y OCPs II] Do Viet Nam ehua ed tieu chuan mdi trudng de ddnh gia chdt luong mdi trudng lidm lieh bien, ehinh vi vdy de danh gia ehat lugng nidi trudng tram lieh cua khu vuc nghien cii'u chiing ldi da so sdnh hdm luong ciia mdt sd bgp chdt huu eo clo vdi ticu chudn \\\\ \ trudng tram tich eiia Canada (bang 5) Trong cac mau tram tich lay lai vimg bien Sdc Trang, tdng ham lugng PCBs dao dgng khoang 2,98-8,50ng/g thap hon so vdi mirc hicu ung ed ngudng-TEL (21,5ng/g) \d Ihap hon rai nhieu so vdi mirc hieu img cd ihe-PEL (189ng/g), vdi he sd d nhiem To: 0,130,39 (bang 5) cho thay tram lich vimg chua bi d nhiem bdi hgp chat PCBs Cae hgp chat thude Irir sau, diet ed (p,p'-DDD, p,p'-DDE, p,p'-DDT va lindane) ed he so d nhiSm khodng 0,008-0,18 (bdng 5), nhu vay tram tieh viing nghien cuu chua cd bicn hien d nhiem bdi cdc hgp chdt Bdng 5- Hdm hrgng ciia mdt sd hap chdt thudc bdo ve thuc vdt vu PCBs trdm lich lay tai viing bien Sdc Trang so vdi Tieu ehuan mdi trudng trdm tfch bicn cua Canada (Dan vi hdm lugng- ng/g: N=22 mini) Hop chiit Ham lirong TEL PEL (ng/g) (ng/g) (ng/g) lie so nliicm (To) 0,008 p,p'-DDD 0,01 1,12 7,81 p,p'-DDE 0,38 2,07 374 0,18 p,p'-DDT 0,01-0,05 1,19 4,77 0,008-0,04 0,01 0,32 0,99 0,031 2,98-8,50 21,5 189 0,13-0,39 Lindaii (a - HCH) T6ng PCBs Ghi chti: To = ham luang ctia cac htjp chJl thu6c trit sau, diet c6/TEL Tteu bun Dig ly, fyja chdt vd Dia vdt ly Biin Mac dil vimg nghien ciru khdng hi d nhiem cac hgp chat PCBs va cac hgp ehat thudc trir sdu diet cd, nhung n6u cu tiep tuc gia tang cdc hgat dgng cdng - ndng - ngu nghiep tai khu vire thi nguy ca d nhi^m cac hgp chat tren la khdng tranh khdi IV CAC G U I PHAP HAN CIIE NGUY CO NHIEM DO CAC HOP C H A T PCBs VA OCPs Nhu chung ta da biet, vimg bien Sdc Trang cd mat hdu het cae hgp phan huu co cua thudc trir sdu gde clo, vdi nhirng mirc ham lugng khac phan bd d nhirng sau khac Qua ket qua Iren eho thay ham luong thudc trir sdu gdc clo va PCBs dugc sir dung theo tirng thdi ky khdc Trong viing cd mgt sd khu cdng nghiep, nha may hda chat, cac boat dgng san xuat ndng nghiep, boat ddng danh bat thiiy hdi sdn dien manh me, giao thdng van tai dudng thiiy phat trien Tuy hdm lugng eac hgp ehat PCBs va OCPs chua vugt qua cdc muc gidi ban cho phep theo lieu chudn d nhiem mdi trudng tram lich cua Canada, nhung vice lang cao ham lugng OCPs va cue dai ham lugng PCBs ldp tram tich tdng mat cua cae cgt mdu la dang luu y Do dd, mdt sd giai phap cdn dua nhdm kiem soat su phdl tan ciia cdc hgp chdt vdo cac hgp phan mdi trudng cu the la: Trong sdn xual cdng nghiep: cdn sir dung cdng nghe cao it phe lieu Khi xdy cdc cdng trinh mdi can ed bien phap xir ly nude ihdi, thai ddm bao miie sach tieu chuan hien dai Irudc dugc thai mdi trudng Can thu gom va xir ly nude thdi va ehat thai r5n - Trong san xuat ndng nghiep: su dung dung cac Ioai thudc tang trudng, thudc bao ve thirc vat dugc Nha nude cho phep, sir dung dung lieu lugng eac ehat bao ve thuc vat, tang cudng sir dung phan bdn huTi co - Ddi vdi chat thai sinh boat: can tuyen truyen van ddng nhan dan ed y thirc bdo ve mdi trudng IChdng xa rae thai true tiep xudng sdng, bien Thuc hien tdt xu ly rac thai cac benh vien - Can cd su phdi hgp giira cac co quan hanh chi'nh, quan ly cap trung uong, dia phuong, cac nha khoa hgc va dan dja phuang nham: Tang cudng hgp tac cdng tac nghien cim va bao ve mdi trudng khu vue Thue hien danh gia tac dpng mdi trudng va cac giai phap giam thieu cac chat d nhiem ngudn gdc nhan sinh cho tat ca cac du an khu vuc Thi6t lap he thdng quan tr^c nhSm kiem soat chat lugng mdi trudng dgc theo sdng, cang bicn va ven bien dc ed the canh bdo va ehuan bi hd so khuyen cao cdc cap cd tham quyen can thiep cd bieu hien d nhiem hay cd su cd mdi trudng Nghiem cam viec thai nude thai, chat thai cdng nghiep va sinh boat xudng sdng, xudng bicn chua qua xir ly Nghiem cam eac tau, thuyen het ban sir dung hoat dgng khu vue Giam thieu cdc cay xang di ddng tren bien va cac hinh thirc budn ban xang dau qui mo nhd Ircn bicn, Hdi nghi Khoa hoc vd Cdng nghe bten loan qude Idn tha I IV KET LUAN Trong tram ti'ch tdng mat, ham lugng tdng PCBs va OCPs dao ddng khoang kha rgng, PCBs: 2,98-8,50ng/g va OCPs: 0,20-0,3Ong/g Sd lugng hgp chdt OCPs duge phat hien ehii y6u tir 3-7 hgp chdt, hgp chat p,p'-DDE cd ham lugng chiem uu lbs Sd lugng hgp chdt PCBs tai khu vuc eira My Thanh va cua sdng xa VTnh Hai eimg !d 15-16 hgp chdt, dd cac hgp ehat chiem chii yeu mau: 2,2',3,4,5,6' Hexachlorobiphenyl; 2,2',3,4,4',5 hexaelorobiphenyl; 2,2',3,4,4',5,5' va tdng 6C1 Trong eac cdt mau tram tieh hop chat OCPs va PCBs cd ham lugng tdng dao ddng khodng 2,98-8,50ng/g va 0,02-(),54ng/g Ham lugng PCBs ca cgt (B08-1123, B081125, B08-13I2) mdu dSu cd xu hudng gidm ddn theo sau Cdn ham lugng PCBs cd su bien ddi d cac sdu khdc So vdi tieu chuan d nhiem mdi trudng ciia Canada thi tram tich vimg nghien ciiu chua cd bieu hien d nhiem bdi PCBs va cac hgp chat thudc bao ve thuc vat Trong vimg nghien ciru cac yeu Id chi phdi dae diem phan bd ham lugng cac hgp chat eo clo ben virng tram tich la che thuy-thaeh dgng luc cua he thong sdng-bien vd eac hoat dgng nhan sinh dien manh me nhu danh bat nudi trdng thuy san, cong-ndng nghiep, che bien hai san va cac hoat ddng giao thdng thuy Day cung chi'nh la ngudn phdl tdn cdc hop chat hiiu ca ben virng cd ngudn goe nhan sinh vao cac he thdng thuy van va bien ven bd ciia viing nghien eiru Do vay can tang cudng cac bien phap quan ly va gidm thieu gia tang cac hgp chdt tren TAI LIEU T H A M KHAO Vu Trudng San (chii bien), 2007 "Khao sat, danh gia tiem nang tdi nguyen khodng sdn viing bien ven bd tinh Sdc Trang, ti le 1:100.000" Luu tru: DC, Ha Ndi Charles R P et al, 1991 Interpretations of contaminant sources lo San Pedro Shelf sediments using molecular markers and principal component analysis Molecular Markers in Environmental Geochemistry, Washington Iwata, H ct al, 1994 Geographical distribution of persistent organoehlorincs in air, water and sediments from Asia and Oceania, and their implications for global redistribution from lower latitudes Environmental Pollution 85, 15-20 Viet, P H et al, 2000 Persistent organoehlorine pesticides and polyehlorinalcd biphenyl in some agricultural and industrial areas in Nolhern Vietnam Water SciciKc and Technology Vol 42 No 7-8 , p 223-229 ... luang hgp chdt OCPs vd PCBs ciia cot mdu B08-1125 lay lui khu vuc ciea My Thanh DOCPs n PCBs 50-72 90 112 u tilt mUa ((.ml Hinh 4- Dd thi bien thien hdm lugng hgjr chdt OCPs vd PCBs ciia col mdu... LUAN Trong tram ti''ch tdng mat, ham lugng tdng PCBs va OCPs dao ddng khoang kha rgng, PCBs: 2,98-8,50ng/g va OCPs: 0,20-0,3Ong/g Sd lugng hgp chdt OCPs duge phat hien ehii y6u tir 3-7 hgp chdt,... eac hgp ehat PCBs va OCPs chua vugt qua cdc muc gidi ban cho phep theo lieu chudn d nhiem mdi trudng tram lich cua Canada, nhung vice lang cao ham lugng OCPs va cue dai ham lugng PCBs ldp tram