Tag chi phdn tich Hog Ly vd Sinh hgc Tap 19, Sd 3/2014 DANH GIA Mirc DO 6 NHIEM ASEN TRONG CAC VUNG 6 NHIEM CHAT DA CAM/ DIOXIN VA PHU CAN TAI SAN BAY BIEN HOA Din toa sogn 21 3 2013 Pham Thi Ngoc Mai[.]
Tag chi phdn tich Hog Ly vd Sinh hgc - Tap 19, Sd 3/2014 DANH GIA Mirc DO NHIEM ASEN TRONG CAC VUNG NHIEM CHAT DA CAM/ DIOXIN VA PHU CAN TAI SAN BAY BIEN HOA Din toa sogn 21 - - 2013 Pham Thi Ngoc Mai Khoa Hda hgc, Dgi hgc Khoa hgc Tu nhiin, Dgi hgc Qudc Gia Hd Ndi Nguyin Hiing Minh, NguySn Van Thu*ng Phdng thi nghiim Dioxin, Cue mdi tru&ng Viet Nam SUMMARY EVALUATION OF ERSENIC CONTAMINATION AT AGENT ORANGE/DIOXIN CONTAMINATED AREAS AND VICINITY AT BIEN HOA AKBASE Soil, sediment, surface water and ground water samples were collected at dioxin contaminated areas and vicinity at Bien Hoa airbase and analyzed by HVG-AAS method to evaluate the arsenic contamination level Results show that among 25 soil and sediment samples, 13 samples have As concentrations from 1.1 to 21 times higher than allowance level Most of them are sediment samples or soil samples taken from dioxin contaminated areas The concentration of As in surface water and ground water were found to lie below the allowance level for groundwater (0.05 mg/L) but some samples exceed the allowance level for drinking or domestic water (0.01 mg/L) The distribution of As concentration in water and sediment has a correlation: areas having low As concentrgtion in sediment samples also have low As concentration in water The contamination of As in soil, sediment and water might be originated from the Blue agent that American army used during Vietnam War, next to the natural origin and domestic activity This study has pointed out the possible risk of As contamination to areas and residence in the vicinity of Bien Hoa airbase, and might form a base to select a suitable dioxin remediation technology that also can remediate As In those places Gidi THIEU CHUNG Trong giai doan chien tranh tir 19611971, quan dpi My sir dung khoang 80 trieu lit chit ddc gay trui la Trong dd, 64 chit Da cam chilm khoang 50% cdn lai la cac chat khac vi dy nhu chit Tring 24%, chit Xanh 6,5% Trong dd, phan chinh cua chit Xanh la Dimethylarsinic acid (Vilt tit la DMA - Cdng thiic hda hgc la (CH3)2AsOOH), chat Xanh dugc bilt tdi vdi tac dung diet cd manh Khi su dyng vdi lilu lugng cao, chit cd tac dyng vdi ca lua va cac loai cay hoa mau khac Mac dil As d dang hiru co it ddc han so vdi dang vd co nhung frong ty nhien, dang hiru CO cua asen cd the b] chuyen dang vd co cac cau oxy va cacbon bi phan buy va cd ddc tinh cao hon nhieu lin [1] Theo mdt nghien ciiu gin day, phan tich dioxin mdt sd miu ily tai cac khu vuc d nhiem dioxin tai cac san bay Bien Hoa, Da Nang va Phil Cat, ciing ddng thdi phat hien thiy ham lugng Asen kha cao, vugt qua quy chuan Viet Nam cho cac loai dat thdng thudng (12 mg/kg) [2] Mdt nhGng gia thiet cd eg sd ve ngudn gdc d nhiem As tai cac viing ndng la viec sir dung chat diet cd cd phan la Cacodylic axit (hay cdn gpi la Dimethylarsinic axit) frong "Chit Xanh" [2] As cd the b] hda tan dl dang ban la dioxin va dd lan truyin d nhilm pham vi rpng ban v l cdng tac xu ly, nlu cac cdng nghe chi loai trir dugc dioxin thi sau xii ly dit cd thi vin chua dupc coi la da sach vi cdn ham lugng As cao Ben canh dd cdn tdn tai nguy co gay phat thai d nhilm As thir cap qua frinh ddt ndng cd thi lam As hda hoi va thoat khdng Chinh vi vay, viec trien khai nghien cuu mirc dp d nhiem As lai cac vimg ndng la hit su:c cin thiet ca ve mat khoa hpc va y nghia thuc tien THU'C NGHIEM 2.1 Hoa chat va thiet hi Cac hda chat loai tinh khilt phan tich (p.a): Axit nifric dac (65%), Axit hydrochloric, Axit H2S04,NaOH, NaBH4, KI, Dung dich asen chuan gdc (1000 mg/l) (Merck), nudc cit hai lin May quang phd hap thu nguyen tu Analyst 800 cua hang Perkin Elmer, Thiet bi sinh hydrua FIAS 100 cila hang Perkin Elmer va cac dung cu thuy tinh khac 2.2 Lay mau vii bao quan mau Tien hanh lay mau dat va nudc d mgt sd khu vuc xung quanh san bay Bien Hda (xem ban lay mau Hinh 1) Mau dat bao gdm ca dat bS mat va theo chieu sau Viec trdn man d cac dp sau khac (0-200cm) dugc tien hanh d hien trudng Mau sau trdn deu dugc chia lam phan (mdi phan khoang 300500g) Man nudc bao gdm ca nudc be mat va nudc ngam, Trong mdt so truimg hgp mau nudc dugc lay d gilng khoan cua nha dan, Cac man nudc duoc axit hda tai hien trudng bing HNO3 (1:1) dl dua pH ciia miu (HVG-AAS) Qui trinh phan 2.3 Phircmg phap phan tich tich mau nuoc va mau d^t dugc torn tit Tien hanh xac dinh ham lugng Asen hinh cac mau dat/ tr4m tich va nuoc bang phuong phap quang hap thu 50 ml nuac Mau - 7inl H2S04 + HN03 diic - dun soi nhe -nghien nho, Ipt silng 0^5 m - dong nh^ mlu 20 ml 1,0 g mau + ml HCI 37% + 2ml65%HN03 + ChiSlvis6ng/20.30' + to ph6ng + loc •^ 25 ml H20 cat - dun soi den xudt hien tring 10 ml - to phong - mo cit Dung djch Can tan 50 ml 10 ml -1.6mIHCIdac+lmIKI - Day chat nip + dun each thii)/25' -10 phong HVG-AAS 50 ml 10 ml + 4ml37%HClHmireKl 4-600010' HVG-AAS (b) (a) Hinh So dd qui trinh phdn tich As (af mdu nu&c; (b) mdu ddt 66 2.4 Phirong phap HVG-AAS As(V) raau phan tich dugc khu ve As(III) bang KI va dugc dua vao bo FIAS de hydrua hoa va ket noi vol may quang hap thu nguyen tu Analyst 800 Xay dung duong chuan a cac dieu kien phan tich g6m: Den: EDL; Dong den: 380 mA; Buoc song: 197,3 nm; Khe sang: 0,7 mn; Bg nguyen tii hoa mlu: Cuvet thach anh; Ngon liia: C2H2 - Khong Giai han phat hien cua phuong phap la 1,2 jig/L Gioi han dinh Iugng cua phuong phap la 3,8 ^xg/L 2.5 Dam bao chat Ivoug va Idem soat chat Iirang Viec dam bao chit lugng va kilm soat chat lugng dugc thuc hien bang each su dung mlu lap hien truong, hai mau trSng trang nia dung cu, mgt mlu liy vao dau tien va mgt mau Ifiy vao cuoi ciing qua trinh lay mlu Cac miu trang nia dugc phan tich de xac dinh miic nhiem cheo giua cac diem lay mau voi va giua tat ca cac mau vdfi Mgt mau trang van chuyen se dugc thu thap tir liic bat dau lay mau va dugc sap xep chung voi cac mau khac, sau giri den phong thi nghiem de phan tich KET QUA VA THAO LUAN 3.1 Ham lirgng As cac miu bun, d i t va tram tich 25 mau dat, bun va tram tich lay tai cac dia diem thugc khu vuc san bay Bien Hoa da dugc tien hanh phan tich ham lugng As Ket qua cho thay ham lugng As dao dgng khoang tu 1,12 mg/kg den 117 rag/kg theo vi tri lay mau Cac ket qua dugc bieu di^n tren Hinh va so sanh voi gidi han cho phep ve ham lugng asen theo QCVN 03:2008/BTNMT- Quy chuin ky thuat quoc gia ve giai han cho phep ciia kim loai nang dat la 12 mg/kg dat kho ^300 D) JC 250 O) S2OO < 150 Ol t ioo — 50 L 12 mg/kg Hinh Biiu dd hdm lugng asen cdc mdu biin ddt, trdm tich tgi khu vuc sdn bay Bien Hod Tit cac kit qua thu duoc nhan tha)- ham bin, dat va tram tich ily tai cac dia luong As frong 13 tren tdng sd 25 mau diem thuoc san bay Bien Hda vugt tir 67 1,11-21 lan ngudng cho phep Hiu hit sd la mau fram tich va mau dit ily tai khu vuc cd lien quan den d nhilm dioxin trade day Dieu cho thay cac mau dit tai khu vuc hen quan din d nhiem dioxin trudc day ddng thdi hi d nhilm asen kha cao va da cd hien tuong nia frdi, lan truyen d nhiem sang ngudn nudc va fram tich tai cac khu vuc lan can 3.2 Hiim lu'ong Asen cac mau nirdc be mat va nirdc ngam tai cac dia diem thuoc khu vyx: san bay Bien Hda • Mdu nu&c be mat Cac ket qua ve ham lugng asen frong cac mau nudc be mat lay tai mgt sd dja diem thudc khu vuc san bay Bieu Hda dugc bieu dien fren dd thi Hinh va so sanh vdi gidi han cho phep ve ham lugng asen cho nudc bl mat va nudc an udng ciia Viet Nam tuong iing la 0,02 va 0,01 mg/L _ 0.025 » 0.02 = 0,015 0,02 m g / l I t, "