L 4.6 Gidi tbieu mot so HCTS-eaphotpho tbiidng diin g:
1.5.1. stt di chuyen da HCBVTV trong moi tnidng.
> - Viec sU dung HCBVTV trong ndng ngliiep, lam nghiep, y te la
ngudn gdc sinh r a ton lUdng HCBVTV trong mdi trUdng. Mot phan HCBVTV p h u n len cay dan den sU ton lUu cua chiing vao thdi diem thu hoach ndng san. Mot phan HCBVTV di vao mdi trUdng xung
quanh va chiu tac dong ciia hang loat cac qua trinh ly, hoa sinh hoc nen chiing bi bien ddi, di chuyen va phan bd lai giUa cac ddn vi trong mdi trudng theo sd do sau [60].
Hinh 3. Su di chuyen cua HCBVTV trong mdi trUdng
1.51.1. Ton iMng HCBVTV trong dat
• Dat la thiing chiia HCBVTV trong mdi trUdng. Dat n h a n
HCBVTV tii cac ngudn khac n h a u . Ton lUdng HCBVTV trong dat da de lai cac tac hai dang ke cho mdi trUdng [60].
- HCBVTV di vao dat do cac ngudn : phun thudc xU ly dat, cac hat bui HCBVTV rdi vao dat, theo mUa lii, theo xac sinh vat vao dat, khoang 50% HCBVTV p h u n len hoa m a u bi rdi xudng dat [33].
- LUdng HCBVTV, dac biet la cac cd clo qua Idn trong dat cd the gay hai cho thUc vat. U N E P [144] cho biet 1 n a m sau khi phun, lUdng
DDT cdn 80%, Undan cdn 60%s heptaclo cdn 10%, andrin cdn 20%. Sau 3nam, DDT cdn 50%. Mot sd' tac gia khac cho thay cac hdp chat cd clo ton tai trong dat tit 4-5 nam, cacbamat ton tai tit 1-2 nam. NgUdi ta Udc tinh 6 n a m sau khi phun, HCBVTV cdn lai tren dat ritng tit 0,17- 0,63 kg/lia [144]. Dat trong rau va cay an qua bi d nhiem nang nhat. Su ton luu cua HCBVTV trong dat phu thudc vao can triic hoa hoc cua chiing va dieu kien khi hau [41, 61]
1.5.1.2. Ton htdng HCBVTV trong nude
Ldp nUdc bim d day song, sudi, ao, ho cung la nhiing cho chiia
khong 16 ddi vdi ton lUdng HCBVTV. HCBVTV vao nUdc hkng nhieu
each : dung true tiep diet cdn trimg va sau bo trong nUdc, cd the tit cac khu ritng hay viing dat ndng nghiep bay den, do nitdc chay qua cac vimg dat dUdc phun thudc mang lai, nUdc thai ciia cdng nghiep san xuat HCBVTV hay nUdc siic rUa cac dung cu phun HCBVTV [130].
Ngitdi ta da Udc tinh cd den 213 tan HCBVTV da theo biu va nUdc mUa do xudng Dai Tay DUdng hang n a m (gidi han tit vi tuyen 0- 30 do biic )[33]. O Lien Xd (cu), lUdng DDT trong nitdc be m a t ciia mot viing trong bong la 0,0004 mg/1, andrin : 0,012 - 1,2 mg/1 [33].
Theo U N E P trong 500 mau nUdc udng va nUdc tU nliien lay tu' song Missisipi va Mitxuri cd 23 mau cd endrin, 5 m a n cd clodrin, mot man cd diendrin cd ndng do qua Idn so vdi TC(3P [138].
- Su d nhiem nUdc do cac HCTS ben viing d dang bid thudc trong khdng khi r a t dang ke. Vi hang n a m cd hang chiic ngan tan DDT dUdc cho vao nude de diet mudi [110].
- Khi HCBVTV lam d nhiem dat, dat cd the lam d nhiem nitdc. C'ac HCTS cd the phat hien trong nUdc gieng, nitdc ao hd d each xa ndi sit (lung HCTS vai kilomet [78].
- HCBVTV trong nitdc se gay tac hai cho cay trong va dong vat song trong nUdc va cud'i cung gay tac hai cho ngUdi [90, 97].
1.51.3 Ton htdng HCBVTV trong khong kin.
• - Su xam nhap ciia HCBVTV vao khdng khi la hau (]u;i tat yeu cua viec sii dung HCBVTV [56].
- HCBVTV cd the d nhiem ban khi quyen bang nliieu ngudn khac n h a u : Su xam nhap titng ddt vao khdng khi (phun thudc) sU xam n h a p dUdi dang bui (long va r^n), sU xam nhap dUdi dang hdi [78], td'c do bay hdi cua HCBVTV phu thudc vao tinh chat hoa hoc ciia chiing, dang tinh the, each sU dung va thdi tiet. Su xam nhap titng ddt ciia HCBVTV vao khdng khi ciing cd the xay ra do gid bao mdn nlntng vung dat khd n h a t trong nhUng cdn mUa Idn hoac bao [33]. Su xam nhap ciing cd the do cac ngudn Idiac. Viec dung H(]TS trong chan nudi, trong bao quan thUc pham hay de lam ve sinh nha ciia trong cdng tac 3 diet ciia nganh y te ciing gay xam nhap HCTS vao khdng khi. Su tliieu can than hay lam hd chu trinh kin ciia viec san xuat HCBVTV se dUa lUdng Idn HCBVTV vao khdng khi. Bui HCBVTV cd the phat tan rat xa [78].Bui HCBVTV d B^c va Trung Phi cd the bay tdi N a m Dai Tay DUdng. TjiyaU^en B^c cUc ciing cd HCTS. Ngudi ta Udc tinh trong 25 n a m cd 2500 tan DDT tdi B^c cUc [33,61]. Ngudi ta da tim thay HCTS - cd photpho trong khdng khi d do cao 50- 200m tit 3-8 ngay sau khi phun bkng may bay[110].
1.5.1.4. Ton htdng HCBVTV trong thuc vat
- Trong qua trinh sU dung, HCBVTV di vao thUc vat mot each
trUc tiep (do phun, rac tren cay), hay gian tiep (qua dat, nitdc, khdng khi bi d nliiem HCBVTV). Cay cd trd t h a n h chat mang HCBVTV de cudi cimg gay hai clio chinh nd, cho ngUdi va dong vat diing nd. LUdng
DDT vao cd the hang ngay tai Canada, My, Anh nh(') ho'n sd litdng cho
phep ciia TCYTTG [33]. 6 cac nUdc dang phat trien,lUdng HCTS dUa
vao cd the qua thiic an thUc vat va dong vat Idn hdn nhieu [84]. Neu ton lUdng DDT trong nUdc la 20 mg/1 thi trong thifc vat sdiig trong nUdc la 31 mg/kg [108]. NgUdi ta ciing thay rkng tren 1 hecta dat xii ly 11,4 kg lindan thi sau 2-3 nam dU lUdng lindan trong khoai tay la 0,6 mg/kg, trong ca rd't la 4,4 mg/kg [108, 147].
1.5.1.5. HCTS trong cd the con ngudi
- Cac tac gia da tim thay DDT trong md md ngudi nhit sau : d Hungari 12,4 mg/kg; d My 6,98 mg/kg ; d (^anada 3,8 mg/kg ; d Ha Lan 2,2 - 7,1 mg/kg ; d Y 16,4 mg/kg ; d Dan Mach 3,3 mg/kg [25,38] d Viet Nam 22,4 ± 14,39 mg/kg [9]. NgUdi ta ciing tim thay DDT trung binh trong huyet t h a n h quan the ngUdi Malaixia la 0,066 mg/kg, xiclodien la 0,022 mg/kg, va d ngUdi My la 0,0015 mg/kg [84].