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Tgp chi Khoa hgc Trudng Dgi hgc Cdn Tha Phdn A Khoa hgc Tu nhien, Cdng nghi vd Mdi irudng 34 (2014) 128 136 Tap chl Khoa hoc TriTdng Dai hoc Can Thtf website sj ctu edu vn DIEN BEEN MOT s 6 CHI TIEU C[.]
Tgp chi Khoa hgc Trudng Dgi hgc Cdn ThaPhdn A: Khoa hgc Tu nhien, Cdng nghi vd Mdi irudng 34 (2014) 128 Tap chl Khoa hoc TriTdng Dai hoc Can Thtf website: sj.ctu.edu.vn DIEN BEEN MOT s CHI TIEU CHAT LlTONG NlTdC TRONG AO NU6l CA TRA {PANGASIANODON HYPOPTHALMUS) THAM CANH Pham Qudc Nguyen', Le H6ng Y^, Nguyen Van Cong^ va Tnrong Qudc Phu* ' Khoa Tdi nguyen va Moi Iruang, Truong Dgi hgc Dong Thdp ^ Trung tdm Quan trdc tdi nguyen vd Moi trudng Cdn Tha ^ Khoa Thuy sdn, Truong Dgi hgc Cdn Tha •* Khoa Moi truong & Tdi nuyen Thien nhiin, Truong Dgi hgc Cdn Tha Thong tin chung: Ngdy nhgn: 05/05/2014 Ngdy chAp nhgn: 30/10/2014 Title: Variation of some water quality parameters in intensive catfish (Pangasianodon hypothalamus) ponds Tit khda: Ao nuoi cd tra thdm canh, Chdt lugng nude hypophthalmus Keywords: Intensive catfish pond Water qualit, Pangasianodon hypophthalmus, cycle ABSTRACT Variation of some water quality parameters in intensive catfish (Pangasianodon hypophthalmus) ponds were investigated in O Mon district, Cantho city Water samples were collected every hours during 24 hours following water column (surface, middle and bottom) at the beginning, middle and the end of cycle Results showned that water temperature, pH, DO, TAN, nitrile, nitrate were different (p0,05) vd ldn luot la 3l,4''C, 29.8 giing thi khdng khdc biit vi y nghia thing ki (p>0,05) vd ngugc lgi: Nhung cgt cd cimg ^ /y (* a cj ^^^ ^ ^ ,^-„g,;, • j ^ ^ „ g j ^ ^ yg^ „/,Q„ ,,i ^ „gf,fa thing ki giua cdc giai dogn nudi (p>0,05: dva vao kiem djnh Duncan) Tap chi Khoa hgc Trudng Dgi hgc Cdn Tho Phdn A: Khoa hgc Tu nhiin Cdng nghi vd Moi trudng: 34 (2014): 128-136 3.2 Diln bien pH theo tang va thM gian nudi Trung binh pH d TM, TG v i TD d diu vu nudi lin lupt Id 6,67; 6,78 v i 6,83 Qua eho thiy, pH cd xu hudng tang dan theo dp siu (Hinh 2) nhung khdng ed sy khdc bilt (p>0,05) Xu hudng tuong ty d dot khdo sdt giiia vu nudi va cao nhdt d ting day (p gidng thi khdng khde biil viy nghTa ihdng ki (p>0,05) vd ngugc igi; Nhiing eat ca cimg ky tv (* ^- '^l cua tieng ling ihi khdng khdc biil vi y nghia thing ke giiia cdc giai dogn nudi (p>0,05: dua vdo kiim dinh Duncan) ~ -•i—ITITTTT3.3 D i l n bien oxy hda tau (DO) theo tang v i giai dogn nudi Oxy hda tan (DO) TM d ddu, giiia vd cudi vu nudi cd gia ui trang binh ldn lupt la 3,12 mg/L, 2,44 mg/L vi 0,58 mg/L; Uong dd xu hudng d TG li 1,56 mg/L, 2,07 mg/L v i 0,58 mg/L va d TD lin lu0 la 1,90 mg/L, 2,28 mg/L va 0,74 mg/L (Hinh 3) Him lupng DO Uong ao d TM phu thu^c chii ylu vio qui Uinh khulch tin oxy qua bi mit vi sy quang hpp eiia phieu sinh thyc vat Uong ao DO d TG vd TD chiu sy dnh hirdng cua qud Uinh hd hap ciia cd, sy phin hiiy chit hOu ca, hoat ddng in mdi vd qud trinh thay nude ao li nhiing nguyin nhdn lam chenh lech DO d cie ting nude ao CJ dau vy nudi gii Uj DO dupe dao ddng khd ldn (0,51 mg/L - 7,55 mg/L), trung binh la 1,90 mg/L, giUa vy DO nhm chung giam so vdi diu vu vdi khoang biln ddng (0,22 mg/L - 6,10 mg/L) ijiung gid hi tiling bmh kbdng khde bilt vdi DO diu vy (2,27 mg/L) Uong dd DO gidm rS ret vao cu6i vu nudi (trung bmh 0,63 mg/L) vd dao dpng Uong khoang 0,01 - 2,36 mgA Kit qud nghien ciiu eho thay DO giim rd vl eudi vy Nguyen nhdn la cang ve cudi vu sy tich luy eia tiiije an diira, sdn phdm thii ciia ci lim vdt chit him co uong biin ddy tang cao (Ll Bdo Ngpc, 2004) Vi vgy hoat dpng phan buy chdt him co cua vi sinh vgt vd boat dpng hd hip ca ldn si lim DO nude eiim thdp (Lefevre et al, 2011) d eudi vy nudi Tgp chiKhoa hgc TrudngDgi hgc Cdn Tha Phdn A: Khoa hgc Tv nhiin Cong nghi va Moi Irudng: 34 (2014): 128-136 Mic dil, gii Ui DO Uung bhih d dau vy, giua vu vd cudi vy lin lupt li 1,90 mg/L, 2,26 mg/L v i 0,63 m ^ nhung DO cd biin ddng ldn tai cac thdi diim thu miu rieng II (0,01 mg/L - 7,55 mg/L) Ci Ua li lodi cd co quan hd hdp phu nen cd the sdng dupe d diiu kiln thilu byt oxy Tuy nhiin, nghien ciiu cua Smith (1982) di chi rang him lupng DO can tiiiit cho qua trinh trao ddi chit Id 3,0-7,0 mg/L Vl vdy, nlu ao nudi cd him lupng oxy hda tan thip thudng xuyIn, sinh vit si it an va hieu qui chuyen hda tiuic an thip hon Uong ao cd ham lupng oxy hda tan binh thudng (Boyd, 1998) DO luon tinh Uang thiiu hut cdn dnh hudng rit ldn din sinh trudi^ ciia ci (Wang et al., 2009) ^•i EE33 ^ ^ KIS3 Diu vu Gii!a vu TAngmSt TAi^giOa Tang day Trang binh CuOi vu Theo thdi gian Hinh 3: Dien biln gii tri DO (mg/L) giira cac tang vi vu nu3i Nhiing CQl cimg dot thu mdu cd kylu (a,b) giong ihi khdng khdc biil viy ngbia thdngke (p>0.05) vd ngugc lgi: Nhiing cgl ed cimg ky lu (A, B, C) eua limg idng thi khdng khdc biil vi y nghTa thdng ki ^Ha cdc giai dogn nudi (p>0,05; dua vao kiem dinh Duncan) 3.4 Dien bien TAN theo tang va thoi gian nuoi Vio diu vy nudi TAN trung binh d TM li 1,66 mg/L, TG Id 1,65 mg/L vi TD Id 1,66 mg/L d giiia vu nudi him lupng TAN Uung binh TM, TG vi TD tdng vi cd gid Ui lin lupt la 3,06 mg/L, 3,09 mg/L vd 3,14 rag/L Vi cudi vy nudi TAN tdng cao d cd tdng vd cd gii ui trang binh d TM, TG vd TD lin lupt li 6,77 mg/L, 6,83 mg/L vi 6,68 mg/L (Hinh 4) Tuy nbiln, bien ddng giua cac ting Uong eiing thoi dilm klido sdt khic bilt khdng qud 0,2 don vi va khdng khde bilt (p>0,05) Nguyin nhdn la hogt dpng boi ldi, dn mdi cua cd v i thay nude eiia ngudi quan ly ao nudi CJ diu vy TAN dao dpng Uong khoii^ 0,3 mg/L - 4,83 mg/L, c6 xu hudng ting ro d giiia vy (1,61 mg/L - 7,56 mg/L) vi cudi vy nudi Mac du, qui Uinh thay nude diln thudng xuyIn (mdi ngiy) nhung gii tri TAN dupe vdn cao (gia Ui cao nhdt phat hi?n Uong ao Id 9,19 mg/L) TAN gia tdng ao nudi li qui trinh phin buy cdc chit hihi ca cd chiia dgm nhu thiic an thira, san phim bii tilt cua ea Thdi gian nudi cdng lau, sinh klidl ca Uong ao cdng nhilu nln vile bii tiet phan vi nude tilu cd cd thi la nguyin nhan chinh ldm ting TAN Theo Boyd (1998) him lupng TAN ao nudi eao sg gay dpc din sinh vdt Hdm lupng TAN thich hpp cho cie ao nudi thiiy sin li tir 0,2 - mg/L Qua cho thdy mac du cic ao nudi dupe thay nude hdng ngdy vao thdi dilm gin cudi vu nudi nhung gii Ui TAN dupe cao hon khuyin cio nhilu lin Niu cae ao khdng dupe thay nude thudng xuyIn thi thiirc in thiia ling dpng d ddy ao eiing vdi cdc chat thii eiia ci vd qua uinh phdn buy chit huu co ao vd neu ehiing khdng dupe logi bd se lim TAN tang rdt cao va gay ddc cho ea kit hpp vdi dieu ki^n pH vi nhiet dp tang sy gia tdng ty ll NH3/NH4* (Emerson et ai, 1975; Ip et ai, 2001) Nguyin nhin do, nude c6 gii trj pH cao (pH ldn hem 7,5) mpt lupng ldn NH4* se bi chuyin NH3 Cu thi, nude cd pH d 25"C thi lupng NH4* ti-ong ting s6 TAN giim di 4% Sy gia ting pH nhu nlu tren dem din kit qua la sy gia tdng lupng ldn dpc Tap chi Khoa hgc Trudng Dai hgc Can Tho Phdn A: Khoa hgc Tv nhiin Cdng nghi vd Mdi trudng: 34 (2014): 128436 tinh ammonia vi gia tang % NH3 Uong nude (lp et al., 2001) Theo kit qud nghiin eiiu ciia Emerson et al (1975 till pH tang tii din 7, 8,9 thi ty ll NH3 ting lin lupt tir 0,1% din 1%, 10%, 50% Nhu vgy, m|ic dii pH Uong ao biin dpng khoing thich hop vdi sy phdt Uiin ciia cd nhung vin cd nguy co giy dpc cho ci ci yeu to pH, nhiet dp vd TAN Uong ao cao AaAa^gA ^ ^ ^ ^ ^^H EX3 TAng m^t TanggiiJa TSng day Trung blnli DSu vu GiJa vu Cuoi vu Theo tbdi gian nuSi Hinh 4: Dien bien gia tri TAN (mg/L) giua cic ting va vu nudi Nhirng cgl ciing dgi thu mdu cd ky lu ('•'') giong ihi khong khde biit vi y nghia thong ki (p>0.05) vd ngugc lgi: Nhiing egl co citng ky lu (^- ^- cm timg idng thi khdng khdc Met viy nghia thing ki giUa cdc giai dogn nudi (p>0,05: dva vdo kiim dinh Duncan) 3.S Diln biin nitrite tbeo tang v i thoi gian nudi Ndng dp niUite ddu vy d TM, TG vd TD lin lupt li 0,98 mg/L, 0,27 mg/L va 0,19 mg/L Oxy dupe d cic ao nudi vio diu vy c6 gia tri d TM eao hon cdc ting cdn lgi Id dieu ki^n cho sy hinh thdnh niUite tir vile oxy hda amonia (amoniac va amonium) uong giai dogn diu eua qua trinh NiUate hda d giiia vy vi eudi vy nudi niUite giam rfl rit So vdi diu vy till d TM chi bing khodng 25 - 32%, TG va TD lin lupt tir 28 - 36% vd 38 - 46;% vi kbic bi^t nhd giiia ting nude Uong ao Ndng dp niUite trang binh diu vy nudi cao nhat (0,98 mg/L) vdi khoing dao dpng tir 0,17 rag/L - 3,03 rag/L vi giim nhanh d giua vu (0,06 mg/L - 0,75 mg/L), trung binh 0,27 mg/L nhung cd xu hudng tang nhe vdo cudi vu (0,02 mg/L - 1,47 mg/L) vdi gid Ui trung binh li 0,19 mg/L Tuy nbiln, biln dpng nitrite d diu vy, giiia vy vi cudi vy nudi khdng cd sy sai kbic (p>0,05) (Hinh 5) Qud Uinh Niuate hda cdn oxy di oxy hda ammonia (amoniac va amonium) thdnh niUite (sin pham trung gian) va tilp tyc su" dung oxy dl oxy boa niUite nitrate (Traong Qudc Phii & VQ Ngpc Ut, 2008) Vi viy, oxy hda tan Uong ao gidm tbeo tbdi gian nudi da dnh hudng den qua trinh Nitrate hda Uong ao li nguyen nhan lira gidm nitrite, nitrate va ting him lupng TAN d giiia va eudi vu nudi Kit qui nghiin ciiu eho thiy, gia ti-i niUite trung bmh biin dOng ldn tir diu vu din cuoivu (0,19 mgiL - 0,91 mg/L) Ham lu^ng nitrite nghiin ciiu ndy hap cac nghien euu Uudc (Cao Van Thich, 2008; Le Bio Ngpc, 2004; Huynh Trudng Giang, 2008) ndng dp 0,1 mg/l nitrite se gdy sdc cho ca va gdy mau niu him lupng khoing 0,5 mg/l (Schmittou, 2004) Theo Boyd (1998) thi him lupng nitrite tiiich hpp eho ed nudi phii nhd ban 0,3 mg/l Nhu v|y, gia tri nitrite dupe Uong ao cd nguy co giy d^c cho ci Tuy nhiin, ngudi nudi ed tiie bdo v? ci khdi sy nhilm dOc niuhe bing eich thim muoi vdo nude Ddy la phuong ^phip quan Upng nhit di bao vl ci nude ngpt chong lai sy nhilm dpc nitrite (Jensen PI ni 2000) Tgp chi Khoa hgc TrudngDgi hgc Cdn Tha Phdn A: Khoa hgc Tu nhiin Cdng nghe vd Mdi Irudng: 34 (2014): 128-136 ^^B ^^^ ^^B l^NI TangmSt Tang giiia T^ngday Tnmg binh Theo thdi gian nudi Hinh 5: Diln bien gia tri nitrite (mg/L) giira cac tang v i vu nudi Nhiing cgl Irong cimg dgt ihu mdu cd ky tv C''') ^dng nhauthi khdng khdc biil viy nghia thong ki (p>0.05) vd ngugc lgi; Nhiing egl ed citng kytvf^^'-) cua timg idng ihi khdng khdc biit vi y nghia ihong ki giua cdc giai dogn nudi (p>0,05, dua vdo kiim dfnh Duncan) 3.6 Diln biin nitrate theo ting v i tbdi gian nu6i Trong dpt khdo sat diu vy nudi, niuate tmng binh d TM, TG vd TD dupe Uong khodng 1,53 1,66 mg/L Tucmg ty, nitrate gin giong d cie ting vio giiia vy nudi nhung giim cdn khodng; 76% so vdi ddu vu (0,86 mg/L din 0,96 mg/L) O cudi vy nitrate tiep tuc giim rd rit d cic tang va cdn khoang 18% so vdi dau vy (0,16 mg/L - 0,30 mg/L) (Hinh 6) Nhin chung, nitrate gidm din theo thdi gian nudi Sy khac bilt nitrate qua giai dogn ciia qua trinh nudi la ket.qua cua qua triph niuate hda vd phin nitrate hda U^ng ao Ylii td ehinh cho qud Uinh hinh tlidnh nitrate la lupng oxy hda tan vi su ddng gdp cua vi khuan nitrate hda (NiUobacter) Uong ao diu vi giua vu nudi cd lupng ojo" hda tan eao li diiu kiln cho sy hinh thinh nitrite v i nitrate Trong diiu kien thiiu oxy (d cudi vy nudi) vi khuin cd thi sir dung nitrate nhu ngudn oxy de thyc hien qud Uinh phin hiiy vit chit hihi co, qui trinh phdn niuate hoa dien d cudi vy li nguyen nhdn lim cho niUate giim, niUite ting nhe trd lai d cudi vy Ket qud khdo sat tgi cic ao cho thiy, gii Ui nitrate trung bmh d dau vu (1,60 mg/L), giua vu (0,91 mg/L) vi cuoi vu (0,23 mg/L) khdng Idn hon nhiiu so vdi gii Ui nitrite Uong cimg tbdi gian tuong img Qua dd cho thiy, qui Uinh chuyin hda dgm Uong ao diln cham va cd chilu budng phdn niuate d cudi vy Theo Boyd (1998) d ndng dp 0,2 - 10 mg/L nitrate khong giy hai cho thuy smh vat Nhu viy, gia Ui nitrate dupe Uong ao vin nim Uong khoing khdng giy h ^ din sy phdt triln cuaca Tgp chi Khoa hpc Trudng Dgi hoc Cdn Tha Phdn A: Khoa hgc Tunhiin, Cdng nghi vd Mdi trudng: 34(2014): ^^> ^ ^ ^^* K^3 T^ngmat TanggiOa Tang day Trung binh Cueii Gifta vu D4UV 1^^'^^^ Theoflidigian nudi Hinh 6: Diln biin gia tri nitrate (mg/L) giiia cic ting va vy nuoi Nhiing cgt ciing dgt Ihu mdu cd kyluC'') gii^g "hau thi khong khdc biit ve y nghia thong ki (p> 0,05) vd ngugc lai; Nhung cot cd citng ky lu f- *• '^l ciia timg tdng thi khong khdc biil vi y nghia thdng ki giUa ede giai dogn nudi (p>0,05: dua vdo kiim dinh Duncan) KET LUAN Nhiet dp, pH, DO, TAN Uong ao nudi ca tra tham canh diu khae bilt (p