HQl NGHI KHOA HOC T O A N Q U O C V E SINH T H A I V A T A I N G U Y £ N SINH VAT I^N THl^ 5
KHAO SAT TINH HINH SAN XUAT VA DlT LlTONG NITRAT
TREN MOT SO SAN P H A M RAU XANH VU XUAN-HETAI HOfPTAC XA HlTONG LONG, THANH PHO HUE
NGUYEN MINH TRI, NGUYEN H^NH TRINH, NGUYEN VIET THANG, NGUYEN THI HOANG PHU'ONG Trudng Bgi hgc Khoa hgc. Dgi hgc Hue
Rau xanh la loai thiic an cung cap nhiSu vitamin va khoang chit cho ccrthe, day la lo?ii thuc pham rat can thiet va co vai tro quan trong d6i voi siic khoe con ngirai. Vi the, rau la thirc pham khong the thieu trong moi bCra an hang ngay cua chung ta. Trong thoi gian gan day, san xuit va tieu thu rau dang doi mat voi van de het sire nghiem trpng, do la sir mat an toan trong cac san pham rau xanh. So vu ngo doc thirc pham tir rau co xu huang ngay cang gia tang. Hien tugng rau khong an toan, chiia nhilu kim loai nang, ham lugng nitrat va hoa ciiat bao ve thuc vat ton du vugt qua muc cho phep dang la van de nong va la moi quan tam dac biet cua cgng dong cung nhu cac co quan quan ly.
Thanh pho Hue la trung tam du Mch cua mien Trung va ciia ca nude, hang nam don khoang hon I trieu lugt khach du Ijch. Do do, van de ve sinh an toan thirc pham noi chung va ve rau sach noi rieng cang phai dugc dam bao de ngudi dan va du khach an tam sii dung. Bai bao nay gidi thieu kit qua vl tinh hinh san xuSt rau va danh gia du lugng nitrat trong mgt so loai rau xanh vu xuan-he nam 2012-2013 d Hgp tac xa Huong Long-thanh pho Hue, nham gop phan vao viec kiem soat sir tich luy nitrat trong rau, hudng den mot nen nong nghiep sach va ben vung, dam bao sue khoe cho ngudi tieu dimg.
1. PHU"OT<G PHAP NGHIEN CUtJ L Doi tuo'ng nghien cuu
+ Cac mau rau an laciia vu xuan-he nam 2012-2013.
+ Mau nude.
2. Phu'O'ng phap nghien cu-u
- Lay mau rau an la ngau nhien tir 5 diem tren rugng vao thdi diem tir 1-2 ngay trudc khi thu hoach. Lay mau phan an dugc cua cac loai rau sau: Xa lach {Lacliica saliva L. var. capitata L.), Cai xanh {Brassica cermia (Thunb.) Forbes et Hemsl), rau Den tia {Amaranthus tricolor L.), ran Mong toi {Basella alba L.), rau Mudng (Ipomoea aqiialica Forssk), Hanh la {Allium u.\calomciim L.), Ngo (rau Miii) {Coriandmm sativum L.)
- Lay mau nirdc tudi cho ran tai cac muong dan nude theo QCVN 08: 2008/BTNMT bang chai nhira PE 1,5 lit.
- Dieu tra tinh hinh sir dung phan bon, hoa chat bao ve thuc vat cho ran bang each phong van trirc tiep nguoi dan tai khu virc nghien ciru.
- Xac djnh nitrat trong nude bang phuang phap trac quang vdi Natrixalixilat [9].
- Chiet nilrat trong ran bang Id vi sdng theo phuong phap cua Pham Huy Dong va Ngo Huy Du (2000).
- Xac djnh nitrat trong rau theo Tieu chuin 452-2001 cua Bg Nong nghiep va Phat triln nong thon [I].
HOI NGHI KHOA HOC T O A N Q U O C V E SINH T H A I V A TAl N G U Y £ N SINH VAT L A N THt> 5 il. KET QUA NGHIEN CUtJ
1. Tinh hinh san xuat rau cua HOTJ tac xa Hirang Long
Chung toi da tien hanh dieu tra ve tinh hinh san xuk, sir dung phan bdn va thuoc bao v? th^rc vat (BVTV) CLia cac hg trong rau tren dia ban phudng Huong Long vu xuan he 2012-2013 trong thdi gian tir thang 12/2012-5/2013.
v l quy mo dien tich trong rau ciia cac hg d Huong Long hau het diu nho, le. Qua dieu tra 6 50 hg trong rau thi chi cd 3 hg cd dien tich trdng rau > 500m^ chilm 6%, trong khi dd cd din 29 ho cd dien tich < lOOm^ chilm ty le 58% va cd 18 hg cd dien tich tir 100-500m^ chilm 36%
(bang I).'
Quy mo trong rau ciJa cac ho dan if Hiro'ng Long Di^n tich fm^)
<100 100-500
>500
S6 hp 29 18 3
Ty \i(%) 68,0 36,0 6,0
Chiing loai phan bdn ma ndng dan sir dung cho rau tai day con r4t tiiy tien, tiiy thugc vao dieu kien san xuat cua tirng hg gia dinh, hau het ngudi trdng rau thudng bdn phan theo kinh nghiem. Trong cac loai phan can bdn cho rau thi ngudi dan chi chii trgng bon lot phan chuong va NPK, tiep den la phan dam, phan lan, cdn phan kali dugc sir dung rat it, tham chi co hg khong bdn.
Tinh hinh sir dung phan bon cho mot so Ioai rau 6' Huo'ng Long
Loai rau
Xa lach Cai xanh M6ng tcyi Rau Mu6ng Den tia Hanh la Ngo
Phan chuSng (l(g/100m') Tircfi
0 0 0 0 0 0 0
Da u 30-90 30-90 30-100 30-80 30-90 30-100 30-100
Phan hoa hoc (kg/IOOm'l D^m
3-4 3-4 3-4 5-7 6 7-10
3
Lan 4 9 9 3 0 15 14
Kali 2-3 0 0 0 0 6-7 2-3
Thd-i gian each ly
5-7 5-7 6-7 7-10 3-5 8-10 5-6 A'gwdrt: Ket qua dieu tra nong ho tCr thang 12/2012-5/2013.
Phan hiru co dugc sii dung tuong doi it va hku hit cac hg dan deu sir dung phan chuong da dugc il hoai muc dl bdn ldt cho dat trdng rau. Lugng phan chudng chu ylu dugc sd d\ing la phan Ign, dao dgng tir 30-lOOkg/lOOm". Ddi khi, ngudi dan d day cdn sir dung ca nude riia chudng trai de tudi rau, dieu nay se lam anh hirdng din chat lugng rauva de gay benh cho ngudi sii dung rau thdng qua chudi thirc an.
HOl NGHI KHOA HQC T O A N Q U O C V £ SINH T H A I VA l A l NGUYEN SINH VAX L A N THl> 5 Sau thu hoach dgt 1, ngudi dan lai bdn thiic bang phan dam cho rau de cay sinh trudng nhanh han. Thdi gian each ly ke tir l4n bdn phan dam cudi din khi thu hoach san pham la dieu dang io ngai. Ket qua dieu tra cho thay, chi mgt vai loai rau dam bao thdi gian each ly ddi vdi dam khi thu hoach vao dgt thu hoach cudi ciing, cdn lai hau het cd thdi gian each ly vdi phan ngan chi tir 3-10 ngay, ngan hon nhilu so vdi quy dinh. Day la nguyen nhan chinh gay ton du NO3'trong rau.
Song song vdi viec dau tu phan bdn de tang nang suat cho rau thi cong tac bao ve thuc vat ciing het sire quan trgng ddi vdi ngudi trong rau. De phdng trir cac loai sau benh cac hg trdng rau da sir dung thude bao ve thuc vat (BVTV) vdi sd lugng Idn va da dang ve chiing loai. Mgt so loai thuoc bao ve thirc vai va thuoc trir sau dugc sii dung tren dia ban nghi6n ciiu nhu:
Abamecmo, Tata 25WG, Reasgant, Tasieu, Dylan, Bassa 50EC, thudc trir sau sat triJng Vifosat...
Bdng 3 Hien trang sir dung thuoc bao ve thuc vnt cho mot so loai rau
TT 1 2 3 4 5 6 7
Loai rau Xa lach Cai xanh Ming \ai Rau IVIu6ng Den tia Hanh la Ngo (rau Mui)
S6 l i n phun/vg 4 4 4 4-5 1-2 5-6 2
Thffi gian each ly (ngay) 3-7 4-6 3-6 2-3 4-6 3-5 2-5 Ngudn: Ket qua dieu tra nong ho tir thang 12/2012-5/2013.
Phan Idn cae ho deu sii' dung thuoc BVTV vdi lieu lugng cao va phun thanh nhieu dgt. Tinh tren mgt lira rau trong mgt vu san xuat tdng sd lan phun la tii 2 -4 lan tiiy theo loai rau, tiiy theo tinh hinh phat trien ciia sau benh. Neu sau khi phun thudc BVTV khong dat hieu qua thi ngudi san xuat sc phun tiep loai thuoc khac. Xet ve mat an toan ed the khang djnh rang vdi tinh hinh san xuat nhu vay se anh hudng den chat Iirgng rau thuang pham.
2. Hien trang nitrat trong nude tuoi rau
Nude tudi rau d day dugc lay tir song Bach Yen dan theo muong vao den eac rugng trdng rau rdi dugc ngirdi dan lay nude tudi eho rau nen sau qua trinh tudi rau, nude se tham xudng dat mang theo lugng phan bdn dugc bdn cho cay va lam cho nguon nude tudi bi d nhiem nitrat do rua trdi tir dat trong rau. Ket qua phan tich ve ham lugng nitrat trong nude lirdi rau dugc the hiendhinh I.
Qua bieu dd d hinh 1, chiing tdi nhan thay ham lugng nilrat trong nude tudi rau d day cd sir ehenh lech nhau giua eac dgi ihu mau va cao hon tieu chu^n B2 theo QCVN 08: 2008/BTNMT ve tieu chuan nude diing cho tudi tieu va thiiy Igi [3], theo dd ehiing tdi tam chia ham lugng nitrat trong nude lirdi rau lam 3 miic sau:
HQI NGHI KHOA HOC TOAN QUOC Vg SINH T H A I V A T A I NGUYgN SINH VAT LAN THtJ 5
Nitrat (mg/l)
20-1 QCVN 08:2008 - B2
I P
1/2013 2/2013 3/2013 4/2013 5/2013 Hinh I. Ham Iirgng NO/ trong nude tudi ' Ham lugng nitrat < 15mg/l: Khdng bj 6 nhilm.
- Ham Iirgng nitrat = 15-25mg/l: Bj d nhilm.
- Ham lugng nitrat > 25mg/l: O nhiem nang.
Nhu vay ham lugng nitrat trong nude tudi rau d Huong Long tir thang 1-4/2013 da bi 6 nhiem nitrat, chi vao thang 5/2013 cd ham lugng nitrat trong nude tudi thap hon so vdi nh&ng thang khac trong vu rau xuan-he 2013 va dat QCVN 08: 2008/BTNMT ve chat lugng nude tudi tieu. Vi the, van de 6 nhiem nitrat tir ngudn nude cd the dugc xem la mgt trong nh&ng nguyen nhan gay du thira nitrat trong rau trdng d day.
3. Phan tich du luo'ng nitrat trong rau
Nitrat la dang chat dam hien dien trong eay rau. Sir dung lugng nitrat it ho|ie vira dii se giiip cho cay rau ed mau xanh, nhin dep mSt. Lugng nitrat cd thi tich liiy trong mdi lo^i rau, phu thugc vao nhieu yeu td, trong dd lieu lugng phan dam sii dung cho cay trdng dugc dac biet quan tam. S\r co mat ciia nitrat trong ndng san se anh hudng xau den sire khde eon ngudi va du lugng nitrat trong mo thuc vat vugt qua nguong an toan duge xem nhu mgt dgc chat [8]. Vi vay nitrat luon dugc xem la mgt trong nliimg tieu chuan de danh gia chSt lugng rau qua. Kit qua xac dinh lugng nitrat ton du trong mgt sd loai rau thanh pham dugc trdng tai Huong Long dugc trinh bay d bang 4.
Bdng 4 Ham luong nitrat trong rau tai phirdtig Huong Long
Ten rau Cai xanh Xa lach Rau Muong Rau D§n Rau M6ng toi Hanh la Ngo
Nitrat (mg/itg P tycri) 542,0±3,98 748,1±5,49 637,3±3,21 675,0±4,95 596,5±4,38 559,4±4,10 1355,5±9,95
FAOn/VHO
<500 S1500
£300
<400
£600
TCVN (*) S600 S1500 S600
£500
£500
£400
£600 Ghi chii: (*): Quylt djnh s6 99/200S/QD-BNN ngay 15/10/2008 cua Bg Nong nghiep va Ph^t trien nong thon vl gidi han tdi da cho phep cua mot s6 vi sinh vat va hoi chSt gay hai trong san phkm rau, qua, chi.
HQI NGHI KHOA HQC T O A N Q U O C V £ SINH T H A I VA T A I NGUYEN SINH VAT L A N THLf 5 Tir ket qua d bang 4 va so sanh vdi tieu chuan cua B d Nong nghiep va Phat t r i l n nong thon ve quy dinh ham l u ^ g nitrat cd trong rau thanh pham, chiing tdi nhan thay rang:
- Xa lach la loai rau an song, ham lucmg nitrat trong rau Xa lach phan tich dugc la 748,lmg/kg trong khi tieu chuan quy dinh la 1500mg/kg. N h u vay, lugng nitrat tich luy trong rau Xa lach dugc trdng tgi day thap hon nhieu so vdi quy dinh va dam bao mire do an toan cho ngudi sii dung.
- Ddi vdi rau Mudng cd ham lugng nitrat la 637,3mg/kg, cao hon so vdi quy dinh v l gidi han cho phep ham iugng nitrat trong rau thuang pham la 1,06 \kn.
- D u lugng nitrat trong rau Den la 675,0mg/kg; cao han so vdi quy dinh la 1,35 lan. Cdn trong Cai xanh lugng nitrat tdn du trong rau la 542,0mg/kg cao gap 1,1 lan so vdi tieu chuan quy djnh. Tuong t u nhu the rau Mdng tai cd lugng nitrat la 596,5mg/kg, cao hon so vdi quy djnh la 1,2 lan. N h u vay theo chung tdi de dam bao an toan eho ngudi diing thi hai loai rau nay c i n keo dai thdi gian sinh trudng them vai ngay nira de den khi thu hoach se han c h i tinh trang tdn du nitrat trong rau.
- D d i vdi rau gia v i : Cac mau Hanh la phan tich dugc ham lugng nitrat la 559mg/kg, cao gap 1,4 lan so vdi tieu chuan Viet Nam cung nhu tieu chuan FAO. Ben canh dd lugng nitrat tdn du trong Ngd la tuang doi cao, cao han nhieu so vdi nhieu mau rau khae va vugt 2,6 lan so vdi quy dinh.
Qua ket qua phan tich cac mau rau thanh pham duge trdng tai phudng Huong Long cho thay da cd den 88,89% sd mau kiem tra bi nhiem nitrat. Day la mgt dieu dang lo ngai cho van de rau sach cho ngudi dan trong dieu kien hien nay. Dieu dang ndi la phudng Hirong Long la mgt trong nhung phudng tham gia vao quy trinh VietGAP tir nam 2009, ngudi trong rau da dugc dao tao nhirng van de ca ban ve trdng rau an toan. Ket qua nay ciia chiing tdi tuong ddi phu hgp vdi mgt so tac gia da khao sat va danh gia d u lugng nitrat trong cay rau trdng tren dat phii sa ven song d Dong bSng sdng Cuu Long cung nhu trdng tren eac vimg dk a Ha N p i deu ed du lugng nitrat kha cao [ 4 ] , [7].
III. KET LUAN
Quy md trdng rau ciia cac hd cdn nhd le nen hieu qua kinh te mang lai dura eao. Viec sir dung phan bdn va thude bao ve thue vat ciia ngudi dan cdn tiiy tien nen da anh hudng khong nhd den chat lugng rau
Ngudn nude tudi cho rau cd ham luong nitrat cao, chua dam bao ve mat chat Iirgng nude dimg cho tudi tieu, do vay se anh hudng den ton du nitrat trong rau thanh pham
Hau het eae mau rau an la trdng pho bien tai Huang Long deu cd lugng nitrat eao han so vdi quy dinh ve rau an toan, rieng chi cd mau rau Xa lach la dat tieu chuan.
TAI LIEU THAM KHAO
1. B^Nong nghiep va Phat t r i f n nong thon, 2001. TCN 452-2001; Phan tich cay tremg-Plmong phap xac djnh Nitrat va Nitrit.
•' Bp Nong nghi9p va Phiit t r i l n nong thon, 2008. Quyll djnh s6 99/2008/QD-BNN: Gidi han toi da cJio phep ciia mot so vi sinh vai va hoa chat gay hai trong san pham ran, qua, clie
3. B9 Tai nguyen va Moi truo'ng, 2008. QCVN 14: 2008/BTNMT Quy chuSn ky lliuat qudc gia v l ch5! lugng nuac mat. NXB. KHKT, H^ Noi,
1. Nguyen Minh Dong, Ngo Ngoc Hung, 2005. Du lugng nitrat trong cay rau Ircn dat phii sa ven song d Ddng bang song Ciru Long. Tap chi Khoa hoc d<4l (28). 70-73.
HQl NGHI KHOA HQC T O A N Q U O C V £ SINH T H A I V A TAI NGUVgN SINH VAT L A N TH1> 5 5. Pham Huy Dong, Ngo Huy Du, TrSn Ttr H i l u , 2000. Chilt Nitrat trong rau bang 16 vi song va xac
djnh ham lugng ciia no b3ng phuong phap Trie quang TuyIn tap Bao cao Hoi nghj Khoa hgc phan tich Hoa, Ly va Sinh hoc Viet Nam l^n thir 1: 200-204.
6. Le van Khoa, Nguyin Xuan Cu, 2002. Phuang phSp phan tich dat nude phan bdn vS cay trong.
NXB. Giao due. Ha Npi.
7. Ngo Thj Phu-ong Lan, 2007. Nghien ciru anh hudng cua mdi trudng dat va nude din chit lucmg rau xanh d Ha Noi. Tap chi Nong nghiep va Phat trien nong thon, so 17: 63-72.
8. D L S., Zhang V. and Lin X., 2007. Accumulation of Nitrate in Vegetables and Its Possible Implications to Human Health. Agricultural Sciences in China 6 (10): 1246-1255.
9. Michael J.«/ al., 2002. Standard methods for the examination o f water and waste water American Public Health Asocialion. Washington D.C.
SURVEY ON THE PRODUCTION AND NITRATE RESIDUES IN SOME VEGETABLE PRODUCTS IN SPRING-SUMMER SEASON
AT HUONG LONG COOPERATIVE, HUE CITY
NGUYEN MINH TRI, NGUYEN HANH TRINH, NGUYEN VIET THANG. NGUYEN THI HOANG PHUONG
SUMMARY
Results on survey and evaluation the vegetable production and nitrate residues In some vegetables products in Spnng-Summer season 2012-2013 at the Huong Long Cooperative-Hue City shows that: The size of the household vegetable cultivation was small thefore the economic efficiency of them were not high. The use of fertilizers and plant protection chemicals was arbitrary, this had a huge impact on the quality of vegetables. Source the water with high nitrate content does not guarantee the quality of water used for irrigation, thus affecting nitrate residues in vegetable products. Most samples of leaf vegetables popularly in Huong Long had higher nitrate residues than the food safely regulations for vegetables, except lettuce samples satisfied the allowed standards.
