su dung svct trong nc danh gia moi truong

8/3/2019 Su Dung Svct Trong Nc Danh Gia Moi Truong

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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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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


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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.


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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.


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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:


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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


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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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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.


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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


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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


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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


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