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8/3/2019 Su Dung Svct Trong Nc Danh Gia Moi Truong
1/12
B GIO DC V O TO
TRNG I HC NNG NGHIP H NI
KHOA TI NGUYN & MI TRNG
BI TIU LUN
CH TH SINH HC MI TRNGS dng to lm sinh vt ch th
trong nghin cu nh gi mi trng nc
Gio vin hng dn: PGS.TS Nguyn Nh H
Sinh vin thc hin: on Th Hng_MSSV:10411325
Lp : LT3MT
H Ni, ngy 18 thng 11 nm 2011
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
Mc lc
I.Khi nim nc b ph dng:......................................................................................................3II.Nguyn nhn gy ph dng:......................................................................................................3
III.c im ca to.........................................................................................................................4III.1S pht trin ni tip nhau ca To..............................................................................4III.2Tc pht trin ca cc nhm to..............................................................................5III.3nh hng ca cc yu t dinh dng ln s pht trin ca To................................6III.4T l N:P v to Lam....................................................................................................7
IV.Cch thc s dng to lm ch th sinh hc cho mi trng nc b ph dng.......................8V.ng dng...................................................................................................................................12
Sinh vin thc hin: on Th Hng_ Lp LT3MT 2
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
S dng sinh vt ch th trong nghin cu nh gi mi trng
To v mi trng nc b ph dng
I. Khi nim nc b ph dng:Nc b ph dng l hin tng tha cc cht dinh dng khong trong mi
trng nc( dng d tiu) lm pht trin mnh mt s loi thc vt thy
sinh( thuc nhm thc vt sn xut: to, rong, ru) pht trin mnh, nh hng
n cn bng sinh vt trong mi trng nc ( a dng sinh hc mt i). Kt qu l
to ra lng ln sinh khi hu c. D cho c pht trin thun li nhng chng vn
cht i v lm tng mn y. Dn n hin tng y ha thy vc v mi trng
ym kh. To ra nhiu cht kh ( H2S, CH4, NH3), ngoi ra n cn chuyn ha cc
ion KLN thnh dng kh ha tan lm tng tnh c trong ngun nc.
II. Nguyn nhn gy ph dng:
Do cc ngun thi cha N, P, Si trong Si quyt nh thnh phn to. Trong
t l N:P> v hm lng Si d tiu thp to mi trng thun li cho to
c ( to silic) pht trin. To ny c mu xm hng, xut hin loi to ny ngi
ta thng gi y l hin tng thy triu .
Ngun thi cha m v ln:
Ngun nc thi sinh hot, nc thi cng nghip : Do trong cha nhiu P
trong bt git, N trong thc n;
Ngun t sn xut nng nghip do s dng phn bn khng hp l; t qu
trnh xi mn ra tri t; t nc ma em xung.
Ngoi nguyn nhn trc tip k trn cn do nguyn nhn gin tip nh: nh
sng, nhit , thi gian c tr.
Trong nc khng b nhim th t l N:P
8/3/2019 Su Dung Svct Trong Nc Danh Gia Moi Truong
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
III. c im ca to
III.1 S pht trin ni tip nhau ca To.
Theo nghin cu ca Lewis (nm 1978) trn sng Lanao Philippines thy
rng, khi mi trng dinh dng thp, thng thng to Khu v lp to Gip trnpht trin trc tin. Khi cht dinh dng tng, tip ni s l to Lc n to Lam
v sao l to Gip hai roi.
Sinh vin thc hin: on Th Hng_ Lp LT3MT 4
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
Theo nghin cu ca Sze ( 1981), trn sng Potomac, qun th to pht trin
dc theo dng chy, to Khu c kch thc nh vi tc sinh trng nhanh pht
trin u ngun ni c dng chy mnh c t cht dinh dng, k tip chng
c thay th bi nhm to c tc sinh trng chm hn l to Khu c kch
thc ln hn v to Lc, cui cng ni c dng chy chm mang nhiu cht dinh
dng th To Lam pht trin. Th nghim ng tm s trn b t ngoi tri cng
cho thy trong sut 30 ngy s pht trin ca to theo trnh t to Khu, to lc sau
cng l to Lam. To Khu pht trin t ngy th 1 v t cc i ngy th 5 sau
gim dn v thp nht ngy th 9 ko di v sau; tip l s pht trin mnh
ca to Lc, chng t cc i ngy th 8-9, qun th to sau c thay th
bi to Lam sinh lng ca chng t cc i ngy th 10-11. ng thi th
nghim trn cng cho thy hm lng ammonia v nitrite thp t ban u v c
chiu hng tng dn v cui th nghim.
III.2 Tc pht trin ca cc nhm to.
Theo ng Hoogenhuot & Amesz (1965); Reynolds (1984) tc pht trin
ca to Lam lun km hn cc nhm to khc. nhit 200C, nh sang bo ha,
trong mt ngy, phn ln to Lam c h s phn i t 0,3-1,4, trong khi to
Khu l 0,8-1,9 v to Lc n bo l 1,3-2,3.
Vi tc pht trin chm nn to Lam thng n hoa sau cc nhm to
khc. Theo Reynolds(1997), vic hiu r v xc nh tc pht trin ca cc
nhm to c bit l nhm to Lam vi cc iu kin thc nghim khc nhau th
rt hu ch cho gii php kim sot s pht trin ca nhm ny.
Sinh vin thc hin: on Th Hng_ Lp LT3MT 5
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
Ngoi tr to Lam, cc nhm to khc b n bi cc nhm Copepoda, Daphnia
v Protozoa, trong khi to Lam ch b tn cng bi virus, vi khun v
antinimycetes m cc nhm ny c t v lun hn ch trong cc thy vc nui. Nh
vy, v c t k th v kh nng t phc hi qun th trnh lng ng cao nn mcd to lam c tc pht trin chm nhng tc suy gim ca qun th thp v
c s n nh mt qun th cao hn cc nhm to khc.
Theo Robarts & Zohary (1987), nhit trn 25 0C phn ln to Lam c tc
pht trin cao nht, nhit ny cao hn nhit ti u ca nhm to Lc v
to Khu. iu ny gii thch ti sao phn ln to Lam n hoa trong sut ma h.
III.3 nh hng ca cc yu t dinh dng ln s pht trin ca To.
S n hoa ca to c th c kim sot thng qua vic xc nh cht dinh
dng cn thit cho s pht trin ca chng. Thm vo , iu c bn cho s pht
trin ca to Lam v cc loi to khc trong thy vc l s ph dng m ch yu
l cc nhn t phosphor, nito v nh sng.
Kh nng lu tr cht dinh dng ca to.
Kh nng lu tr cht dinh dng trong c th to c lin quan mt thit n
kh nng duy tr sinh khi ca to trong thy vc. Cc yu t quyt nh n sinh
khi v kh nng duy tr qun th to bao gm:
Hm lng Nito v phospho cn bn sn c trong thy vc.
Cng nh sng chiu vo thy vc.
Kh nng lu tr ny cao hay thp.
Trong cng mt thi im ch cn hn ch 1 trong 3 nhn t trn l c th gii
hn sinh khi ca to. Cc yu t gii hn s pht trin ca to thng thay i
theo v tr a l v theo thi gian, th d ni c v cao ( vng n i, hn i)
cng chiu sng vo nc thay i lin quan n gc ti v di ca ngy.
vng nhit i, cng chiu sng v nc thng thay i lin quan n c
ca nc. Trong sut ma ng hoc trong vc nc c, nh sng lun l nhn t
gii hn, trong lc hm lng N v P lun y cho s pht trin ca thc vt.
Khi cng nh sng gia tng vo ma xun hoc khi thy vc tr nn trong
hn, cc nhm to bt u pht trin cho n khi cc ngun dinh dng hon ton
cn kit. Nu hm lng cht dinh dng cao, to s pht trin mnh lm c
gia tng v lc ny nh sng tr thnh nhn t gii hn s pht trin ca to.
Nito:
Sinh vin thc hin: on Th Hng_ Lp LT3MT 6
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
Nito c th i vo thy vc t t, hoc t s cho n qu d tha, v t vic
phn hy cht thi hu c trong thy vc. To ly nito ha tan v c dng
nitrate, nitrite v ammonia. Theo Reynolds (1997), trong nhng vng t acid, nito
c xem l nhn t ch yu gii hn s pht trin ca to. Tuy nhin, cng cnhiu kin khng xem nito l yu t gii hn s pht trin ca to Lam v mt s
ging loi to Lam (Anabaena, Aphanizomenon) c th ly nito t khng kh
b vo s thiu ht nito cho qu trnh pht trin ca chng, nhng nhng ging
loi ny li ch xut hin khi mi trng d tha nito. Quan trng hn qu trnh c
nh nito i hi nng lng nh sng cao v s khng c hiu qu khi thy vc b
c do mt to qu dy bi hin tng n hoa.
Phospho
Cng ging nit, phospho c t vic phn hy cht thi hu c nn y thy
vc, dng phosphate sinh hc sn c n gn kt vi vi keo t cht hn nitrate. V
vy, ngun phospho ch yu i vo thy vc l t t nh t b mt b ra tri v
s xi mn. Mc d t l P:N cn thit cho sinh khi to pht trin ch l 1:7 nhng
phospho cn hn nit v n l nhn t gii hn s pht trin ca to. To lam v
nhiu ging loi to c kh nng thu nhn v d tr phosphate cho c th chng.
Chng c th cha phophate cho 3-4 ln phn chia, kt qu l 1 t bo c th
phn chia thnh 8-16 t bo m khng cn thu nhn phosphate v sinh khi ca
chng c th tng gp 10 hoc hn na khi phosphate ha tan hu nh cn kit. V
nguyn nhn ny, nn khng th da vo nng ln ha tan m d on s pht
trin ca sinh khi to.
Phospho trong cc thy vc t nhin c rt t, ch c nhiu mt s thy vc
nh: cc vng t thp ca sng, mt vi h to ra bi ni la v mch nc ngm.
Hn na, kim sot phospho i vo vc nc d dng hn l kim sot nit, bi v
phng php hn ch phophorus t cht thi ni ti th n gin v tt hn kim
sot nit thng qua qu trnh nitrate v kh nitrate. Hn na, vic hn ch nit li
c th c n b bi qu trnh c nh nit t khng kh bi nhm to Lam
trong khi khng c c ch n b phospho.
III.4 T l N:P v to Lam
Theo Schindler (1977) v Smith (1983), vic xc nh t l nit:phospho l
quan trng bit c khi no to Lc hoc to Lam pht trin vo ma h. Mt
cch tng qut, t bo to i hi khong 10-15 nguyn t nit cho mi nguyn tphospho. Khi N:P cao, tc phospho ca mi trng thp, t bo i hi cung cp
Sinh vin thc hin: on Th Hng_ Lp LT3MT 7
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
phospho, lc ny to lc chim u th hn cc nhm khc bi kh nng sinh
trng cao hn ca chng. Khi t l N:P thp mt s to Lam c th pht trin
mnh v chng c kh nng tng hp nit ca kh tri. Seymour (1980), ngh
thay i t l nit:phospho ngn chn s pht trin ca to Lam. Tuy nhin theoSmith (1988), iu ny ch c tc ng n thnh phn ging loi ca to m t c
tc ng ci thin tnh trng thiu oxy do s n hoa ca chng gy nn. To Lam
dng nh cht t ngt nhiu hn v gy nn mi hi hn cc to khc, cho nn
vic tm ra t l nit:phospho ngn chn s pht trin ca to Lam th cn thit.
Theo bo co ca Shillo (1965) khi nghin cu h Canada cho thy khi bn nit
t 7-18g/m3/tun, hon ton loi c to Lam, ng thi to Lc v to Khu s
thay th. Tuy nhin, nhng ao nui thy sn lun c nng nit v c cao s c
to Lam pht trin mnh.
Theo Luuc et al. (1999), to Lam c mi lin h cht ch vi nng nit v
phospho trong thy vc hn l cc loi to khc. iu ny c ngha l chng c th
cnh tranh mnh hn cc nhm to khc iu kin mi trng phospho v nit b
gii hn. Hn na, to Lam c kh nng d tr phospho mt cch ng k, chng
c th cha lng phospho thc hin vic phn chia t 2 n 4 t bo, iu
ny tng ng vi vic gia tng sinh khi ca chng gp 4-32 ln. T l
nit:phospho thp c l thun li cho s n hoa ca to Lam. Theo Schreurs
(1992), t l ti u N:P ca nhm to c nhn tht (16-23 phn t N:1 phn t P)
vi t l ti u N:P ca nhm to tin nhn (10-16 phn t N: 1 phn t P ), t l
ny cho to Lam l thp hn cc nhm to khc.
IV. Cch thc s dng to lm ch th sinh hc cho mi trng nc b ph
dng.
Quan st mu nc trong h bng mt, c cc dng mu nc nh sau:
Bng so snh mu nc trong ao nui tmNc thin nhin khng c mu. Mu sc ca nc ao h do cht ha tan
trong nc to nn.+ Mu xanh: do s pht trin ca to lc, to lam v cc loi thy sinh. (Mu
xanh t chui v mu vng nht l tt cho c. Khi mu nc t xanh xm thphi cho thm nc mi pha long, v khi c nng nhiu, to s quang hp v
Sinh vin thc hin: on Th Hng_ Lp LT3MT
Xanh m Nu m Vng nu
Vng t Trong c ph sa
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
tng nhanh sinh khi. Khi v m s lng to cht nhiu, s phn hy ca chngs lm tng mc tiu hao oxy, tc s lm nhim nc nc ao)
+ Mu nu : do cc cht mn hu c. (Khi mu nc ao chuyn sang dngny th cn tin hnh ht bn y ao).
+ Mu vng gch: do c nhiu st. Mu xm, xanh en: do nc thi sinhhot v nc thi cng nghip. (Loi nc ny nu dng nui c th qu trnh x ls lm chi ph tng cao)
Ch : Nu ao c mu xanh qu m do to th phi ngng bn phn hay thaync.
+ Hin tng thy triu (red tide) v hin tng n hoa nc (water
bloom) thng lm cho cc Ao nui thy sn tht thu hay lm gim cht lng
thy sn , c bit l cc c t c tnh cht tch ly trong c th vt nui.
Sinh vin thc hin: on Th Hng_ Lp LT3MT 9
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
Mi e da ca khu h ng - thc vt nc
Thy triu (red tide), hin tng n hoa nc (water bloom) l thut ng
ch s n hoa ca cc loi vi to. y l hin tng t nhin xy ra do mt t
bo vi to gia tng ln n hng triu t bo/lt (thng thng c khong 10 - 100
t bo vi to/ml, nhng trong trng hp n hoa mt c th ln trn 10.000 tbo/ml) lm bin i mu ca nc bin t xanh lc m, cho n vng xm
(ngi dn ven bin thng gi l nc cm, nc mn ca).
Hin tng thy triu c lin quan cht ch ti s ph dng ca thy vc.
Nguyn nhn ca hin tng trn c lin quan n cc yu t mi trng nh:
nhit , mn v hm lng mui dinh dng cng nh cc trng kh - thy
vn. Ngoi ra, cc cht thi t hot ng ca con ngi nh nui trng thy sn
thiu quy hoch, s pht trin ca cc nh my ch bin thy sn, ha cht cngl mt trong cc nguyn nhn dn n s hnh thnh Thy triu . Hu ht cc
Sinh vin thc hin: on Th Hng_ Lp LT3MT 10
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
loi vi to bin n hoa thng a n hu qu lm cho mi trng xu i, hm
lng oxy ha tan suy gim nhanh chng, gy nh hng nghim trng n i
sng thy sinh vt.
To cht v chm xung y thy vc v b phn hy bi cc vi sinh vt khcc bit l vi khun.
Kt qu gy nn hin tng thiu xy trong cc tng nc lm cht cc loi
thy sn. Qu trnh ny lm thay i thnh phn ha hc trong nc, gy tng cc
kh c. n nay, cc nh khoa hc xc nhn c khong trn 300 loi vi to
hnh thnh s n hoa lm thay i mu nc. Trong c khong 1/4 loi (70 - 80
loi) gy hin tng n hoa c kh nng sn sinh c t ang l mi e da n
khu h ng vt v thc vt t nhin nc, ngh nui trng thy sn v sc khe
ca con ngi (nguyn nhn do c t to c th c tch ly trong vi loi ng
vt thn mm s, c hay c v khng b ph hy trong qu trnh un nu, khng
nh hng n mi v ca thc phm. Do vy c ng dn cng nh ngi tiu
dng kh c th xc nh c cc thc phm bin b nhim c do to gy ra.
Hin nay, c 5 loi triu chng ng c do tiu th thc phm bin nhim c t
to xy ra vi con ngi. Trong , c bit dng ng c gy t lit c (PSP) c
th gy t vong v dng ng c Ciguatera rt ph bin trong vng nhit i. Theo
cc nh khoa hc, trong vi thp k qua, hin tng Thy triu v n hoa nc
ang gia tng c 2 kha cnh tn s/cng xut hin v phn b a l.
Ti Vit Nam, hin tng Thy triu cng xy ra nhiu ni. Tuy
nhin, khu vc bin Bnh Thun l ni c tn sut n hoa ca vi to cao nht, hin
tng ny dng nh xy ra hng nm vo khong thng 3 n thng 8, khi nhit
m li v cng bc x cao nht trong nm. Cng trong thi k thng 7 - 8,
hin tng nc tri t ra mnh nht, nhiu nh khoa hc cho rng hin tng
nc tri cng c quan h mt thit n s n hoa ca vi to. ng thi, ngh sn
xut ging thy sn v nui lng cc loi tm hm, c m cng thi ra mi trng
mt lng dinh dng ng k cng l mt iu kin kch thch s n hoa. Hi n
tng n hoa nc thng xy ra trong cc h nc ngt v cc ao nui thy sn.
Theo cc nh khoa hc, hin tng Thy triu v n hoa nc l mt trong
nhng vn cp bch cn c quan tm nghin cu c th, lu di nh: V quy
lut pht sinh v lan truyn ca hin tng Thy triu v n hoa nc; v sinh
thi pht trin v sn sinh c t ca mt s loi vi to k c cc loi ang hnhthnh c kh nng n hoa. Trn c s , c s cnh bo bo v sc khe cng
Sinh vin thc hin: on Th Hng_ Lp LT3MT 11
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Khoa ti nguyn v mi trng Bi tiu lun mn Ch th sinh hc mitrng
ng, ng thi nh gi y v nhng thit hi m n gy ra.
Cc loi To thng gy n hoa nc gy c hi: Harmful and toxic algae
Microcystis, Anabaena, Oscillitoria, Hapalosiphon and Anabaenopsis,
Cylindrospermopsis and Aphanizomenon. Alexandrium, Pseudo-nitzschia,Gyrodiunium, Dinophysis
B con nui thy sn nn ch qun l cht ch thc n cng nh ngun thi
trnh hin tng Ph dng ca ao nui cung nh cc thy vc khc ni ngun
thi tp trung.
IV.1
V. ng dng
Sinh vin thc hin: on Th Hng_ Lp LT3MT 12
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