B TRlCH Gf ClfA Ll/GfNG

XAC DINH HAM Ll/GfNG THUY NGAN, ASEN, SELEN TRONG CA THU, CA TRlCH Gf HAI BEN CA ClfA HOI (NGHE AN) VA THACH KIM (HA TINH) TS.NGUYEN QUOC THANG TrUdng Dgi hoc Hd Tinh Tom tat: Trong bdi viet ndy chung tdi tie'n hdnh phdn tich ham luang cdc nguyen td thiiy ngdn, asen, selen (mercury, arsenic, selenic) trong cd thu (Acanthocybium), cd trich (Clupeidea) d hai ben cd Ciia Hoi (Nghe An) vd Thach Kim (Hd Tinh), ddy Id nhiing nguyen td cd doc tinh cao. TU ke't qud nghien ciiu dd dUa ra cdc ket ludn ve ham lut/ng cua chung cd trong cdc ddi tUOng nghien ciiu, du dodn sU 6 nhiem cdc nguyen td ndy trong nUdc bien d hai VLing ndi tren, de cd nhiing nhdn xet vd khuyen cdo cdn thiet. \. Mof dau Cung vdi sff phdt trie'n manh me ciia qud trinh cdng nghiep hda da't nffdc, chat thai cdng nghiep cung dang ngay mdt tang ve sd' Iffdng, da dang ve chiing loai, trong dd cd kim loai nang gay nen hien tffdng d nhiem mdi trffdng. Hien nay, van de d nhiem kim loai nang Irong cac ngudn nffdc dang dien ra d nhieu nffdc tren the' gidi. Cdc nha chuyen mdn ve ve sinh an toan thffc pham canh bdo rang nhieu loai ca sinh sd'ng trong vung nffdc d nhiSm rat de lich tu cdc kim loai nang nhff Hg, Se, As... cac loai chat nay cd nhieu trong chat thai chffa dffdc xff ly triet de Iff cac nha mdy, xi nghiep, cd sd san xua't theo ddng chay cdc con sdng dd ra bien. Vi vay, viec phan lich ham Iffdng cac nguyen td' thuy ngan, selen, asen trong thffc pham cd y nghia. B. thQc te. Qua dd, de' ddnh gid ham Iffdng va cd nhffng khuye'n cdo can thiet nham tim bien phdp giam thieu cdc kim loai nang Hg, Se, As (ne'u cd) nham bao ve sffc khde cho nhan dan. Thiiy ngan, asen, selen la cdc nguyen Id' ddc hai, ham Iffdng cdc nguyen Id' nay dffdc qui djnh theo tieu chuan Viel Nam va lieu chuan ciia Id chffc Y te the' gidi dffdc trinh bay trong bang 1 Bdng 1: Tieu chudn ve ham lugng cho phep Hg, Se, As trong thUc phdm[] ]. Xuan huyen Nghi Ldc tinh Nghe An. Dia diem 2: Ca thu va ca trich d ben cd Thach Kim, huyen Ldc Ha tinh Ha Tinh. , Ca dffdc lay nguyen con dffng trong tui nilon sach. Chgn nhffng con ddng deu, khdng bi dj lat. Ghi ma sd' vao tui ngay lai ndi lay, bao quan trong thung lanh kin rdi chuyen ve phdng thi nghiem. Tao mau khd: Miu ca Iffdi lay d bien ve rQa tren v5i nffdc chay, de cho khd rao, Igc la'y phan Ihjt can thit Iffdi (khdi Iffdng mo) sau Tieu chuan Viet Nam Tieu chuan Nguyen Id' dd dem hong (TCVN) WHO khd trong iff 0,5mg/kg 40g|a/kg Hg nhien d ndi Se 130-150tig/kg thdng gid trdnh As 0,5mg/kg 400^g/kg dnh nang mat De phan tich ham Iffdng cdc trdi (selen de bay hdi), sau khi ca nguyen id' chung tdi chgn 2 khd dung cdi sff gia nhd thanh bdt, dffng bdt ca vao tui pdhme phffdng phap phan tich la phffdng phdp kich hoat notron, day, bao quan mau khd lai phdng Ihi nghiem trong lii say d nhiet phffdng phap phd'/ ha'p thu nguyen iQ. Cac phffdng phdp dd 55OC. nay dffdc thffc hien lai Vien Nghien cffu hat nhan Da Lat. 2. Ke't qua nghien cQu [2, 3, 4,5] 2.1 Chuan bi " mdu Dia die'm 1 : Cd thu (Acanthocybium) va ca trich (Clupeidea) d bien CQa Hdi Ben cd Thach Kim. thudc xa Nghi Anh: Q.T. so KHOR HOC & CONG NGHC HR TINH. ). 2.2. P/tiicfngpiidp kich Itogt notron Bdng 2: Cdc thong so hat nhdn thich hop cho phdn ling kich hoat dd'i vdi cdc nguyen to cdn nghien ciiu TT 1. Nguyen Do phd Phan ffng hat nhan bien td Il27(n,y)ll28 1 100 Hg202(n, Y) Hg203. 2. Hg. 29.8. 3. Se. 0.87. S,e^\n, Y)Se75. 100. As''5(n,Y )As''6. 4. As. hoat do phdng xa trong thdi gian 3.600 giay, de xdc djnh thiiy ngan, selen mdu dffdc de' ra trong thdi gian 10 ngay va do hoat do phdng xa trong thdi gian 10.800 giay. Phd gamma ciia cac nguyen to dffdc ghi tren delecter Ge sieu Chu ky ban EY WY tinh khie't. ra Tl/2 Sau khi tie'n hanh chieu xa va 443 16,9 25 phiit tinh todn ke't qua bang phffdng 47 ngay 279 81,5 phap so sdnh, chung tdi linh dffdc 265 59,1 ham Iffdng cdc nguyen to ciia 4 120 ngay 559 44,6 miu. Ke'l qua dffdc cho trong 26.5gid bang 1 (ham Iffdng cdc nguyen td' dffdc tinh Iheo trgng Iffdng khd). He do budc xa gamma - Detector sieu tinh khie't HPGe: Ma hieu: Ortec-GMX 30190 Dd phan giai: 2,2 keV lai dinh 21332 keV ciia 60Co Hieu suat Iffdng dd'i la 30% - Khoi dien tii: MCA: Accuspec/A, Canberra Khuech dai: 2026- Canberra ADC: Onboard - Phdn mem: L Genie-2k, Ko-Dalat Dung cu, hda chdt - Can phan lich dien tQ: Do nhay: IO"^g. G/«(c«/i.-0,00001-180g - Bao bi dffng mau chieu - Ni td Idng - Cha't chuan so sanh, can tinh khie't - Mdy han nhiet, kep, thia la'y miu - Hop nhQa dffng mau do Chung ldi sff dung phffdng phdp phan lich kich hoat notron dung cu theo nguyen lac: Mau phan tich va mau chuan dffdc chieu xa ddng thdi trong Id phan Qng, thdi gian de ngudi, thdi gian do nhff nhau (dd'i vdi mdt nguyen Id). Tinh loan theo phffdng phdp so sdnh. Can chinh xdc mau cd can nghien cffu tff 0,30,5gam, ca'n than ddng gdi bang bdt nilon sach sau dd cho vao conlaind nhdm rdi tien hanh chieu xa mau. Dd'i vdi cdc nguyen id nay, chiing tdi tie'n hanh chieu xa dai, thdi gian chieu xa la 10 gid tai mam quay, cdng suat Id 500 kW, thdng Iffdng notron la 2.10'2n.cm'2.s-l. De xdc djnh asen, chiing ldi lien hanh de ra trong thdi gian 3 ngay, do. Bdng 3: Ham lugng cdc nguyen td theo phuong phdp NAA (dan vi tinh: mg/kg) Nguyen td^. Hg. Se. As. 1. Ca thu CQa Hdi. 0,67. 3,12. 6,03. 2. Ca Ihu Thach Kim. 0,33. 0,51. 3,04. 3. Ca trich CQa Hoi. 0,38. 4,11. 31,63. 4. Ca trich Thach Kim. 0,31. 3,90. 24,82. TT. Kini! ; . A., fi. l i i t i j . TJ - 3-1*',:,; T v : ' 5/;iW[;.;. I l i n h T H i i . Sc. Tl ' l O f e T d - i i l n a i y ; 1 ; - HISWSMY. Hinh 1: Phd gamma cua cdc nguyen id' SO KHOR HOC & CONG NGHC Hfl TINH. (1. 2.3. Phuang phdp quang phd hdp thu nguyen tii [3,4] Can 5g/lmlu khd rdi cho vao binh Kendal dung lich 250ml, cho vao 10 - 20 ml HNO3 dam dac va 1 ml H2SO4 dam dac, lac deu va de' yen 20 • - 30 phut. Dun ndng cham tren bep dien de'n khi nhan dffdc dung dich trong sudt. Chuyen dung dich miu vao cdc thiiy linh chju nhiet va dun tren bep dien de'n can khd. Hda tan can bang 4 ml nffdc cat rdi chuyen vao binh do AAS. Mau dffdc do tren may AA-6800. Cdc thdng sd' dffdc Hg. Se. As. 253,7 0,1 CV-AAS. 196 0,5 HG-AAS. 193,7 0,2 HG-AAS. Nguyen to Bffdc sdng (nm) Dd nhay (ppm) Che do do. chgn nhff bang 3 Ke'l qua phan lich ham Iffdng cac nguyen Id' Iheo phffdng phdp AAS dffdc dffa ra d bang 4 Bdng 4: Hdm lugng cdc nguyen td dugc xdc dinh theo phuang phdp AAS (ppm) Nguyen td. TT 1 2 3 4. Ca Ca Ca Ca. thu CQa Hoi thu Thach Kim trich CQa Hdi trich Thach Kim. Hg. Se. As. 0,62 0,27 0,35 0,34. 3,03 0,50 4,01 4,11. 5,91 3,00 33,2 22,7. De so sanh ham Iffdng cdc nguyen id'bang hai phffdng phap phan lich iren, chung ldi dffa ra d bang,5. Bdng 5: Hdm lugng cdc nguyen td trong cd theo cdc phuang phdp NAA vd AAS (Dan vi tinh mg/kg) Nguyen td'. NNA. AAS. Ca thu CQa Hoi. Hg Se As. 0,67 3,12 6,03. 0,62 3,03 5,91. Ca thu Thach Kim. Hg Se As. 0,33 0,51 3,04. 0,27 0,50 3,00. Ca trich CQa Hoi. Hg Se As. 0,38 4,11 31,63. 0,35 4,01 33,2. Ca trich Thach Kim. Hg Se As. 0,31 3,90 24,82. 0,34 4,11 22,7. Nguyen td. 16. SO KHOfl HOC & CONG NGH€ Hfl TINH. TQ sd' lieu neu ra d bang 5, chung tdi nhan Iha'y cac ke't qua phan dch d hai phffdng phdp la kha gan nhau, dieu nay cho phep chung ldi nil ra ke'l luan la cdc so lieu thu dffdc la lin cay. Nhff vay, ham Iffdng cdc nguyen Id' thiiy ngan, selen nam dffdi ngffdng cho phep ve ve sinh an loan thffc pham theo TCVN va Iheo lieu chua'n the gidi, bien d hai vung nay chffa cd dau hieu d nhiem hai nguyen td' nay. Ham Iffdng asen trong ca trich d ca hai viing cao hdn so vdi TCVN, dieu nay cd the la do kha nang tich tii asen cao ciia loai cd nay. 3. Ket luan Da de'n hanh phan lich cdc nguyen td' thiiy ngan, selen va asen trong cdc mau cd thu va cd trich d hai vung bien tren bang phffdng phap phan tich kich hoat notron, phffdng phdp phd ha'p thu nguyen iff. Cdc ke't qua phan lich cho Iha'y: Ham Iffdng cac ddc to' Ihiiy ngan, selen ciia 2 loai cd, asen d cd thu d hai vung bien nam dffdi ngffdng gidi han cho phep. Ham Iffdng nguyen td' asen d trong cd trich d hai khu vffc bien Nghe An va Ha Tinh la hdi cao va vffdt ngffdng Iheo QCVN, dieu nay cd the dff doan la sff tich Iuy asen trong cd trich la ldn, hdn nffa loai cd nay sdng gan bd hdn. Tff ke'l qua phan lich cdc nguyen id d tren, cd the' dff dodn bie'n d hai vung nay chffa bj d nhiem cac nguyen td' nghien cffu (ngoai trff asen trong cd trich hdi cao). N.Q.T Tai lieu tham khao / ; ; Bo Y te. Quye't dinh 3742/2001/QD-BYT: "Qui dinh danh muc cdc chdt phu gia duac phep sii dung trong thUc phdm" Hd Noi (2001). [2] Bo KH&CN. TCVN 6626 : 2000 (ISO 11969 : 1996) Chdt lugng nUck: Xdc dinh hdm lugng asen. Phuang phdp do phd hdp thu nguyen tii'. Hd Noi (2000). [3] Bo KH&CN. TCVN 5989 : 1995 (ISO 5666/1 : 1983) Chdt lugng nudc. Xdc dinh thiiy ngdn tdng sd bdng quang phd hdp thu nguyen tii khong ngon liia. Phuang phdp sau khi xii ly vdi tia cue tim. Hd Ndi (1995). [4]. Trung tdm Tin hoc-Bo Thiiy sdn. Mot sd nhdm loai cd bie'n xudt khdu chinh, Hd Ndi (2000). [5] Doe. Sioete D. Neutron activation analysis. Vol 34, 210-540 (1972)..