Trả lời Câu hỏi DCMT

8/9/2019 Tr li Cu hi DCMT

1/18

Vit Nam c 16 lu vc sng c din tch lu vc ln hn 2.000 km 2, trong c10 lu vc c din tch ln hn 10.000 km 2, l cc sng: Hng-ThiBnh, BngGiang-K Cng, M, C, Thu Bn, Ba, ng Nai, Cu Long, Srpok, S San (xembng 1-2). Theo thng k bng 1-2 ch c hai sng ln l sng Thu Bn vsng Bac ton b din tch tp trung nc nm chn vn trn lnh th Vit Nam.Hu ht ccsng c ca sng ra b bin thuc lnh th Vit nam (tr sng BngGiang-KCng, sng S San v sng Srpok).a hnh ni non v kh hu nhit i gi ma tc ng su sc ti lngv phnphi lng nc trong nm. Ti nguyn nc ca Vit Nam c nhng cim chnhnh sau:1) Phn b khng u theo khng gian v thi gian. Trn lnh th cnhng vngnc rt phong ph: lng ma trung bnh nm xp x 2000 mm, c nilng matrung bnh nm trn 3800 mm. Nhng cng c vng ma rt nh, lngma hng nmt di 1500 mm, c bit ch t xp x 800mm (vng Phan Rang).Lng dngchy hng nm ch yu tp trung vo khong 3 thng ma l, chim 80%tng lngdng chy hng nm, ma kit ko di gy kh khn cho cp nc. 2) Ncta c tng din tch l 331.000 km 2 th c n 75% din tch l i niv tp trung ch yu min Bc, Ty Nguyn v khu vc min Trung, cnli l ngbng ph sa v chu th, ch yu l ng bng sng Hng v sng CuLong.3) a hnh min ni to ra tim nng ng k v thu in v d trnc. Tuynhin cng l nguyn nhn gy l, l qut v xi mn t. 4) L, ng lhin tng xy ra thng xuyn gy thit hi ln cho nn kinh tquc dn.Vng ng bng ven bin, hin tng nhim mn cng gy kh khn chosn

xut nng nghip v cp nc cho nng thn.

Cu hi ca Thy:


2/18

1. Lm sao bit tng ngho nc v tng giu nc

2. Quan h gia nc ngm v nc mt

3. c th c bn ca ti nguyn nc Vit Nam

4. Tc ng ca h cha nc i vi mi trng dng h lu

5. nh hng ca vic khai thc nc ngm

6. Ti sao Vit Nam b loi ra khi cc nc giu ti nguyn nc

7. Ca s thy vn, nc ngm

nh hng ca vic xy p v h cha nc i vi mi trng nc, t phlu sng. Li ch v hn ch ca vic xy h, p?

Tr li:

p p tr nc va mang li li ch rt to ln nhng ng thi cng mang nhu qu xu khng nh.

Mt tro lu ca th k 20.

T xa xa con ngi bit p p tr nc, ch yu dng cho sinh hot v nngDu tch cc p t nht t 3000 nm trc cng nguyn tm thy Jordan, Ai Cvng Trung ng. Nhng ch n na sau ca th k 20, xy p mi tr thnh mtlu mnh m do nhu cu pht trin cng nghip, thu in v phng chng l lt. Tthng k nm 1998 ca U ban p nc th gii (WCD), nhn loi xy dng 47nc ln trn 150 nc. Nm nc c nhiu p nht l Trung Quc 22000 ci, H

6575 ci, n 4291 ci, Nht Bn 2675 ci v Ty Ban Nha 1196 ci. Theo khu vng u l chu vi 31340 ci, tip theo l Ty u 4277 ci, chu Phi 1269 ci, u 1203 ci, Nam M 979 ci, Bc v Trung M 801 ci, chu c v cc nc chu gn cnh 577 ci. ln cn Vit Nam, ngoi Trung Quc, Thi Lan c 204 ci, Lo 1Campuchia 1 ci. Thi gian xy dng cc p thng 5-10 nm v trung bnh mi n


3/18

gii c thm 160-320 p mi. Vic xy p tng nhanh n mc chng mt vo nhnm 70, khi mi ngy c 2 hoc 3 p ln c hon thnh ni no trn th ginhng nm 90, trung bnh mi nm chi ph 32-46 t USD xy dng cc p ln, m

phn nm s p cc nc ang pht trin vi kinh ph u t 22-31 t USD.

Tc ng ca cc p ln i vi mi trng

p chia ct cc dng sng ra khi cc vng ng bng ngp l v cc vng t ly chng v lm gim vn tc dng chy trong sng. p tc ng ln cc mu hnh di cca cc loi c v cc mi trng c tr l ven sng nh cc thc, ghnh, b sng v cvng t ly. Cc mi trng c tr ny l ni kim n v sinh sn quan trng i v

nhiu loi sinh vt sng di nc cng nh trn cn; v chng ng gp ng k vvic duy tr cc dch v h sinh thi khc, c th l vic lc nc. p cng cn tc ti cc mu hnh di tr ca cc loi c, ngay c khi cc bc c c xy dng, v bc ch c hiu qu nh mt bin php di c cho mt s hn ch cc loi, nh c hi.

Bng cch lm chm li s chuyn ng ca dng nc, p ngn cn s di chuynnhin ca bn ct h lu i vo vng chu th, vng ca sng, vng rng ngp n

vng t ly v vng bin ni a, nh hng ti kt cu v nng sut ca cc chnV d nh ngh c ven bin ph thuc vo dng chy n t thng lu mang li thSau khi p Aswan trn sng Nil hon thnh, cc cht photphat v silicat cung cp chovng ven bin b gim xung cn 4 % v 18 % mc trc khi xy dng p. iu nlm gim thc n cho c, cng vi vic tng mn trong chu th gy nn do gimdng chy x ra sau p v s nh bt qu mc trn sng Nile, kt qu l sn lngngh c ven bin b gim i ng k.

Kh nng gi bn ct cng c th nh hng n s vn hnh p v lm gim tuiti a d kin ca chng. M, mi nm khong 2 km3 dung tch h cha b mt i do bn ct bi lp, mc thit hi hng nm ln ti 19 triu USD. Bn ct l vn ch


4/18

c gii quyt trong vic qun l v vn hnh p, mt thch thc i vi ngnh nlng v p.

p ngn gi nc, hn ch hoc lm gim dng chy ma xun hoc nhp iu l, nhng yu t ny thng ng vai tr quan trng trong vic duy tr cc h sinh thi vt ly v vng ven sng h lu. Khi p ph v nhp iu ny, cc mi trng c trvng ven sng v vng t ly v cc chng loi sng s b mt i. Vic vn hp cng nh hng n cht lng nc. V d nh cc p c c xu hng x ny h cha, thng l lnh hn v c hi n cc loi quen chu nhit m hn. Nhng thay i v nng xy ha tan v thc n cng nh hng ti cc loi c sh lu. Thi gian v lng nc x nhn to t cc p ln cng gy tc ng ng chng him khi sao chp ng chu trnh l t nhin trn cc h thng sng t nhin.

Cui cng, nc v hm lng bn ct cn nh hng n cht lng nc v kh kh bn ca sng (kh nng phn hy cc cht nhim hu c). Nc chy chm tcc h cha b phn lp thay v c trn u nh trc , trong nc y hthng kit qu xy. Lp nc ngho xy ny c th to nn kh hydro sulfua c hlm suy thoi cht lng nc. Ngoi ra, nc ngho xy c x t p xung s gim kh nng kh bn ti tn 100 km v pha h lu v kh nng ny ca nc snthuc trc tip vo nng xy ho tan trong nc.

Cng cn lu rng cc tc ng ny khng ch gii hn bn thn cng trnh p; cng trnh c s h tng i km vi p, nh ng dn vo tuyn cng trnh, ntruyn ti in hoc knh ti, cng gy nh hng tiu cc. p thng l mt phtrong cc k hoch pht trin vng, ni c nhiu p c xy dng trong cng mt

vc hoc ni m nc c chuyn t cc lu vc giu nc sang cc lu vc thinc. Quy m gia tng ca nhng s chuyn nc gia cc lu vc ny lm ny sinhvn mi trng rt nghim trng.


5/18

Tt c cc tc ng ny dn ti tn tht khng lng trc c ca s a dng sinnc ngt v lm gim kh nng sn xut ra thc n v cc dch v ca cc h sinh tthy sinh m con ngi ph thuc vo chng.

Li ch ca vic xy h, p

Trong th k 20, cc p ln c coi l mt trong nhng cng c hiu qu nht vic s dng v qun l ti nguyn nc. Hn 45 nghn p ln thc s ng vai quan trng tr gip ngun nc cho cng ng v pht trin kinh t, sn xut lnthc, cung cp in nng, phng chng l lt v dng trong sinh hot. chu , mcs dng p cha bao gm ti 63%, thu in 7%, tr nc 2%, ngn nga l l

a mc tiu 26% v cc mc ch khc 4%.

Cc p cha p ng mt nhu cu rt ln nc ti v sinh hot. Mt na s p dng cho ti hoc ban u l ti v 30-40% ca 271 triu hecta t c ti nhp, ng gp 12-16% tng lng thc th gii. Dn s th gii trn 6 t v mi ngcn c 50lt nc ngt sinh hot mi ngy hay hn 18,25m3/nm. Ngy nay, mi nmnhn loi cn 3800km3 nc ngt, gp hai ln so vi 50 nm trc. Trong , 67% cho nng nghip, 19% cho cng nghip, 9% cho dn dng v sinh hot. Vo nm 202c 3,5 t ngi sng vng thiu nc, gp 6,5 ln hin nay.

Nhu cu in nng vn cn rt ln. Th gii c khong 2 t ngi ngho nng th c thnh th cha c dng in. Thu in cung cp 19% in nng hn 1nc trn th gii, trong c 24 nc da 90% vo ngun in nng ny.

L lt l mt trong nhng thin tai kinh hong nht ca nhn loi. Vo nhng nm t1972 n 1996, l tc ng n cuc sng ca hng trm triu ngi, gy hi hn bmt tai ho no, k c chin tranh, hn hn v nn i. Vi s lng p tr nc hin c, chng ng vai tr tch cc phng chng l lt v gp phn gim nh thiny.


6/18

Cc p cha cn mang li mt s li ch khc nh iu ho kh hu, tng qu t nnc v ngh c nc ngt. Trong s 957 khu t ngp nc c tm quan trng Qu(Ramsar Site) vo cui 1998, c 10% l khu t ngp nc h nhn to bn cnh 2

khu t ngp nc h t nhin.

Hn ch ca vic xy h, p

Li ch cc p rt ln, nhng hu qu ca chng ngy cng c nh gi l nghimtrng v c th nhn loi cha nhn thc ht c. Tc ng tiu cc n mi trnsinh thi do chng gy ra khng ch trn lu vc, m cn rt ln vng ca sng v

b, khng ch qui m a phng, m cn qui m khu vc, ton cu. . V phndin dn sinh-kinh t, cc cng trnh p c nhng tc ng trc tip, lm khong 40triu ngi phi di di cng vi nhng thit hi c th, hoc khng th b p ti sn, c s h tng, vn ho cng ng, nhng mt mt ti ch v ti nguyn nhv thin nhin. Mt mt ti nguyn thin nhin v tc ng tiu cc v mi trng sithi khng ch ti ch, m trn ton lu vc, k c thng ngun, h ngun v vng bin ven b m trn 60% tc ng khng c tnh n khi thit k p.

Hin nay, nhng bin ng mi trng ton cu lin quan n nhn tc tm v mthuc v hai vn quan trng nht. Th nht l bin i kh hu, trong c gia kh nh knh lm tri t nng ln do hot ng cng nghip v ph rng. Th hai l ssuy gim nghim trng ngun vt cht t lc a a ra bin do sng chuyn ti, bgm nc, trm tch v dinh dng. Mt tri t c chia thnh ba i c bn l ldi ven b v i dng. Di ven b theo quan im v tng tc lc a v i ddi ven b (LOICZ) bao gm c vng thm lc a. y l ni tp trung ti nguyn tnhin, dn s v cc c s kinh t quan trng nht ca nhn loi. Hng nm, mt lnc ngt khng l t lc a ra di ven b, mang theo 13,5 x 109 tn vt cht rlng, 1,5 x109 tn vt liu di y v 4 x109 tn vt cht tan. Qu trnh tng tc v ti vt cht gia lc a v i dng di ven b to nn mt th cn bng ng trng, sinh thi v c cu ti nguyn thin nhin. Qu trnh ny xy ra hng trm


7/18

triu nm trong nhng hon cnh c a l khc nhau v trng thi hin ti c bn thit lp trong 6-8 nghn nm qua. Ch vo na sau th k 20, cc p, bn cha ni v nc ti lm gim 60% nc sng v km theo l mt lng rt ln cht rn

ho tan b lu gi li lc a. Phn b ca phn cn li khi a ra bin cng b thay su sc. S mt i t ngt mt lng rt ln nc ngt, trm tch v dinh dng di ven b gy ra nhng hu qu nghim trng nh xi l b bin, xm nhp mn, i ch thy vn, mt ni c tr v bi ging, bi ca sinh vt, suy kit dinh v gim sc sn xut ca vng bin ven b, dn n thit hi ln v a dng sinh ngun li thy sn nh bt, nui trng.

V d r rt nht l vng ca sng Hong H, mt trong nhng con sng ln nht

gii. Lu lng nc v trm tch ca sng ny gim mnh t nhng nm 1950 do h thng nc ti v 8 p ln nc ti v thu in dc sng. Ti Trm thu Lijin cch ca sng 105km, ti lng nc 49,1km3/nm vo nhng nm 50 ch cn15,4km3/nm vo nhng nm 90. Ti lng trm tch 1,3 x 109 tn/nm vo nhng n50 gim xung ch cn 0,287 x 109 tn/nm vo nhng nm 90. Nc trn lu vc sHong H dng cho cng nghip, nng nghip v sinh hot 12,2 km3 vo nhng nm tng ln 30 km3 vo nhng nm 90. S suy gim nc v trm tch ca sng mnh vu nhng nm 70 ch yu do xy p cha Sanmenxia, mnh nht vo nhng nmkhi p cha Xiaolangdi ln nht trn sng c xy dng vi dung tch cha 12,7 m3 nc v chng gi li h 9,75 t tn bn ct. Hong H tr thnh sng chy theo mv khng cn dng chy h lu. Ti Trm Lijin, vo 1972 c 19 ngy trong nm,nhng n nm 1997 c ti 226 ngy trong nm khng c dng chy, d rng lng trung v thng lu vo nhng nm 90 gp 1,7 ln nhng nm 50.

Nhiu p khc cng lm gim ng k nc v bn ct l lng xung h lu sng vven b. p Farakka trn sng Hng n lm gim 75% dng chy xungBangladesh. S bi t chm ca chu th sng Nin vn c duy tr sau khi p pnc Delta vo nm 1868. Hin nay, p Aswan lm gim mt lng nh nc snnhng li gi li lng trm tch rt ln. p ny cng cc p khc gy xi l 5


8/18

8m/nm, c ch t 240m/nm trn phn ln b chu th. B bin Togo v Benin anxi l 10-15m/nm do p Akosombo trn sng Volta Ghana by gi trm tch a bin. Trn sng Rhone Php, cc p nc lm gim bi tch a ra a Trung

t 12 triu tn/ nm vo th k XIX, nay ch cn 4-5 triu tn/nm, gy xi l 5m/ncho bi bin vng Camargue v Longuedoc, gy tn ph rt ln cho bo v b bin.

C nhiu dn liu v mi lin h gia p v s suy gim lng c ca sng ven p Aswan lm gim ng k c mi v mt s loi c khc ven b a Trung Hi.Hng nm Senegal b mt 11250 tn c do p p Niger. S suy gim ny do thng ngun gy ra nhng thay i v iu kin sinh thi ven b, gim ngun dindng, mt ni c tr v bi ging, bi , mt ng di c sinh sn ca c. p

ng di c ca c ln thng ngun hoc xung h lu. Trn sng Columbia, lnhi b git khong 5-14% mi khi vt qua 1 trong 8 p ln khi ngc sng. C mhn ch cu vt cho c c thit k khi xy p, v d nh 16 cu vt trn 450 Nam Phi v 9,5% trong s 1825 p M. p Pak Mun trn sng Mekong Thi Lcng c thit k cu cho c vt. Tuy nhin, hiu qu ca cc cu vt thp. Ntrong s 34 cu vt cho c trn 40 p, 26% hot ng tt, 41% khng tt v 32%khng hot ng c. Ni chung, 36% cc d n p khng p ng c vn dca c. Khng ch gim ti lng nc, ch dng chy thay i cng to nn btcho mi trng sng ca cc loi thu sn. chu th Zambezi, dng chy ma thaydo p lm mt 10 triu USD tin tm ven b.

Dng nc ngt lm tng sn phm c bin do lm tng dinh dng v c nhiu trc, c con ca sng, ven b chu th. Gn y, khi nh gi tc ng ca mt p ba bc c tn l Three Gorges chun b xy dng trn sng Trng Giang, gio s C

T. A. C. (2000) i Loan, pht hin ra mi quan h ng bin gia lng ncdo sng ti ra v lng c bin ng Trung Hoa. Theo ng, dinh dng photpho tsng a ra bin rt nh v s gim phot pho do p p trn lu vc khng ln. Tlng photpho v nit ca cc sng Trung Hoa v Hn Quc, k c Trng Giang vHong H, vo bin ng Trung Hoa tng ng l 9 t v 100 t moles v t s N/P


9/18

111, ln hn nhiu t s Redfield N/P l 16, thch ng vi qu trnh to nng sut s ca thc vt ni. Do vy, ngun photpho ngho kit, trong khi nit tha d trong nngun gc sng. Lp trm tch mt y bin ven b vn kh giu phot pho ngun g

sinh vt. Ngun photpho quan trng trong nc tng mt thc vt ni pht trincung cp nh hot ng ca nc tri thng ng t y ln, lin quan n c ch c bng nc-mui do c ngun nc ngt t sng a ra. Ngun nc ngt ra bin sgim nhiu khi p Three Gorges trn sng Trng Giang c hon thnh. Nu dchy sng gim 10% th s lm gim trao i nc theo mt ct ngang thm lc khong 9%, da trn cn bng nc- mui nu trn. Do vy, ngun dinh dng, cl mui photpho gim mnh trong nc tng mt, nng sut s cp v sn lng c

gim tng ng. Tnh hnh ny tng t vi s kin El Nino kh nng v ma t lmdng nc ngt t sng ra gim hn v lng c nh bt cng gim theo. V d, ng Trung Hoa, sau El- Nino 1982-1983, sn lng loi c thng phm quan trn Navodon sepient gim trn 60%, tng ng lng ma ven b gim 50%.

1. Th no l instream use v offstream use ? Phng hng v cch thc trong qul nc?

Tr li:

Nc dng trong vic ti tiu, chn nui, nhit in, cc qu trnh cng nghip, v

trong cp nc cng cng vic s dng nc trong sinh hot l mt hnh thc caoffstream use. Trong trng hp nc khng quay li dng chy ngay lp tc sau s dng. l lng nc bay hi, lng nc c hp th vo cc sn phm hov ma, v lng nc tiu th bi ng vt v con ngi.


10/18

Instream use lin quan n nc c s dng din ra trc tip t ngun. V d nhdng nc sng trong hng hi, thy in, nc dng lm ch cho c,ng vt hoad, gii tr.

Phng hng v cch thc trong qun l nc:

a) Gia tng s cung ng nc s dng xy p, h cha nc nhn to v knh o b) Khai thc nc ngmc) S kh muid) Ma nhn to

Bo tn nc:

Mt s phng n nhm bo tn nc

a) Gim s tiu hao nc do thy lib)Gim hao ph nc trong hot ng cng nghipc) Gim hoang ph nc gia dng

2. Nu nhng tnh cht ca nc? Ti sao nc l dung mi qu nht?

Tr li:

hiu nc di dng s cung cp, s dng, s nhim v qun l, chng ta trcn hiu bit v mt t nhng c trng c bn ca nc. Nc l mt cht lngth thay th, khng c n, chng ta khng th tn ti c. Mi phn t nc chnguyn t hydro v mt nguyn t oxi. Mi lin kt ho hc m gi cc phn t linhau l lin kt ho tr, c ngha rng mi nguyn t hydro chia s n in t ca nnguyn t oxi v nhng nguyn t ny chia s nhng in t ngoi cng ca nnguyn t hydro.


11/18

S thc nc l mt cht phn cc lin quan n nhiu c tnh quan trng ccng nh cch thc n phn ng trong mi trng. Chng hn, nhng phn t nkh nng thu ht ln nhau, v vy chng sn sinh ra nhng lp mn mng hoc nh

tng phn t nc gia v xung quanh nhng ht quan trng trong s chuyn nnc trong i khng bo ha pha trn mc nc ngm. Qu trnh ny l trong s s dnh kt . Nhng phn t nc c th b ht li ,u m ca phn t nc (oxynhng ion dng nh natri, canxi, magi v kali. Bi v nhng ht st c khuynh htch np cc ion m, chng thu ht nhiu ion dng hn (hydro) v nhng phn t ns c hydrat ho. Cui cng s phn cc ca nc l nguyn nhn sinh ra sc cmt ngoi : nhng phn t nc thu ht ln nhau cng nhiu hn so vi nhng ph

ca khng kh. Sc cng mt ngoi v cng quan trng trong nhiu qu trnh sinh havt l ko theo nhng chuyn ng nc xuyn qua nhng khe h.

Nc thng c coi l dung mi c bn. N c kh nng ha tan nhu chkhin n tr thnh mt b phn c bn v quan trng ca cu thnh s sng. V nnhin c tnh acid yu, chng ho tan mt lng ln hn hp t mui n gin cht khong v . Nc c bit quan trng trong s phong ho ho hc ca v

cht khong, cng vi nhng qu trnh l ha v sinh ha, bt u s to thnh t. Nc l cht duy nht m th rn nh hn th lng, iu gii thch hin

bng tan. Nu nc th rn nng hn th lng th n s chm xung. Mc d ci nan ton hn cho nhng con tu i du lch gn nhng ni bng tri, nhng thuc tnh sinh quyn nhiu khi khc nhau: dng sng, i dng ng bng t y ln trn.

c tnh quan trng khc ca nc l tnh b ba ca n, nhit , p sut v ba

ca n: rn (nc ), lng (nc), kh (hi nc) c th tn ti cng nhau. Bi bnc xut hin t nhin trn hay gn b mt tri t.

iu c mi lin h quan trng trong vic chuyn nc t cc i dng vquyn v sinh quyn theo vng tun hon nc. Th gii s tr thnh mt ni khc


12/18

ton nu nh nc khng th bc hi t i dung vo kh quyn ngay ti iu ki b mt (chu trnh nc dng li).

Nc tri t cho php lm du hiu ng v mi trng bi v nhit dung ringca n. Nhit dung ring l bch phn tng mt gam cht lng ln mt .ndung ring ca 1 calo/gam c so snh vi nhng dung mi c nhit dung ring kho0.5 calo/gam. Nc c kh nng ln nht ht v gi nhit.

3. Ti sao bng li ni trn nc?

Tr li:

Nc c mt c tnh kh c bit.Khi nhit trn 4 C vn c c tnhging mi vt khc l nng n lnh co; nhng khi nc di 4 C th c tnhca nc s ngc li, tc l lnh n nng co. 4 v khi t khi ca n s lnnht. Cng mt lng nc , sau khi kt thnh bng th tch ca n s gin n/

Nhng lp bng trn sng h hay trn chum nc vo ma ng u ng trn b mnc, cha bao gi xy ra trng hp lp bng ng di y nc. Nu t mt t bng trong nc, n s lun ni trn b mt nc. iu ny chng t bng nh hn

V nc khi ng bng n ra, nn bng nh hn nc v ni ln trn mt n

nh th m lp bng ni trn mt nc bo v lp nc di n khng b ng Do , khng bao gi c hin tng nc sng, bin, h b ng bng ton b xuny. Nu khng nh vy cc sinh vt di bin lm sao c th tn ti c.

4. Bin php bo v ti nguyn nc ngm. Nu cc c ch gy nhim ngun ngm.

Tr li:

a) C ch nhim nc ngm :

- Tc nhn t nhin nh nhim mn, nhim phn, hm lng Fe,Mn, v mt s loi cao hay cc tc nhn nhn to nh nng kim loi nng cao, hm lng NO- ,NO2-

,NH4+ ,PO43- ,vt tiu chun cho php cng vi s phn hu cc cht hu c, cc h


13/18

cht ho hc c cha trong a tng a cht sinh ra cc cht theo nc b mt nxung v ho tan vo trong nc ngm.

- Do k thut khoan, lp t ng nc khng khoa hc lm xut hn cc ca s

cht nhn to.

+ a nc nhim t b mt xung

+ a nc nhim tng nc trn xung tng di

b) Bin php bo v ti nguyn nc ngm:

Cn tng cng cng tc qun l ngun nc

Lut ti nguyn nc, c quan qun l Nh nc cn tng cng qun l ngun ny li cc hin tng xm hi ngun nc nh: khai thc ba bi, thm d v khaikhng php, thi cng cc cng trnh khng ng quy trnh gy h hi ngun nc...

y mnh cng tc truyn thng

Thc t cho thy a s ngi dn cn t bit v nguy c nhim ngun nc, v tca nhng vic lm v thc dn ti ph hng ngun nc v nhng bin php ptrnh nhim ngun nc...

Cc phng tin truyn thng i chng cn tng cng cc ni dung lin quan tv ngun nc, trang b kin thc cho qun chng mi ngi c th gim st cng lin quan ti ngun nc nhm pht hin cc hot ng sai tri gip cho c chc nng. Ch khi no ton dn quan tm ti bo v ngun nc th mi c th gi

s trong sch ca ngun nc cho mun i sau.

Cn c cc ch ti thch hp

Thi hnh lut ti nguyn nc cn phi y mnh v tht nghim tc.


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Ap dung khoa hc k thut cng ngh hng ti cc ngun nc sch hn

a) B sung nhn to nc ngm :

iu tit ngun nc gia ma ma v ma kh (tch tr nc tha trong mama s dng trong thi k cn kit v ma kh). Ngn chn hoc y li s xm nhp ca nc mn t bin vo cc tng chanc ngt di t vng duyn hi hay s xm nhp ca nc thi c hi t ctrung tm dn c, cng nghip. Trong trng hp tng nc ngm b nhim bn trc th sau khi c np nnc sch t ngoi vo, cht lng nc ngm s c ci thin. To cn bng p lc trong lng t, chng li s st ln b mt do khai thc nngm hay do tho kh m. Nh tr lng nc c b sung, mc nc ngm dng cao, lm tng mt, to iu kin cho thc vt pht trin, chng nn sa mc ha.

Vic b sung nhn to nc ngm thng c thc hin bng cc phng php cyu sau y:

Xy dng cc cng trnh tch tr nc ma, nc mt, nc l di dng h cknh o... t nc thm vo lng t, b sung cho cc tng cha nc ngm nnng (phng php thm thng ng). Trong trng hp tng cha nc nm su hoc b ph bi lp cch nc dylm cc cng trnh hp thu nc di dng l khoan, ging o, l ng... c chiu ln cho nc t trn mt xm nhp t nhin hoc c nn p vo tng cha n

(phng php chn vi). Sau khi c np, lng t bin thnh "kho cha nc ngm", c dung tch lnkhng chim nhiu din tch t ai trn mt, li hn ch c s tn tht do bc hKhi cn ly nc ngi ta mi "m kho" bng cch khoan ging bt c ni no t


15/18

phm vi phn b ca tng cha nc v bm ht ln dng ngay ti ch, khng c phi lm ng dn di nh cc cng trnh khai thc nc mt.

b) Mt s qu trnh c bn x l ngun nc ngm

- Lm thong s b: mc ch s dng ngun oxy trong khng kh oxy ha chp cht II ca St (Fe) v Mangan (Mn) to kt ta. Ngoi ra cn loi tr CO2 tronnc nhm nng cao pH y nhanh qu trnh oxy ha v thy phn kim loi.- Clo ha s b: nhm oxy ha Fe v Mn ha tan dng phc hu c, trung halng Amoniac (NH3) d v dit khun to nhy trn b mt lp lc.- Khuy trn ha cht: nhm phn tn u ha cht phn vo nc khi x l.

- Keo t v to bng cn: thc hin vic kt dnh cc ht cn keo phn tn thnh bng cn c kh nng lng v lc.- Qu trnh lng lc: nhm loi tr cc cn v bng cn, tch cc cn nh khnglng c nhng c kh nng bm dnh trn b mt ht lc. Ngoi ra cn gim lnkhun c trong nc.- Hp th v hp ph than hot tnh: kh mu mi v cho nc. y cng l cchl tng cng nu phng php x l thng thng khng p ng.- Flo ha nc: nng cao hm lng Flo trong nc ln 0,6 -0,9 mg/l nhm bo vmen rng v xng cho ngi s dng nc.- n nh nc: kh tnh xm thc v to mng bo v cch ly khng cho nc xc trc tip vi vt liu mt trong thnh ng dn.- Gim cng nc: loi tr cc ion Ca2+, Mg2+ khi nc n nng yu- Kh trng v kh mui: dit vi sinh gy bnh, tch bt mui ha tan di dncation v anion trong nc.- i vi vic x l nc p dng trong iu kin sinh hot gia nh chng ta c b qua mt s quy trnh m cht lng ngun nc s dng vn m bo.

c) Bin php kh st trong nc ngm


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Trong nc ngm St thng tn ti Fe (II) di dng mui tan Fe(HCO3)2, FeS,FeSO4... Vi hm lng st cao nc c mu vng, mi tanh, gy nh hng khngn cht lng nc sinh hot v sn xut. Ngun nc ngm c phn loi theo

lng st nh sau:

- Nc ngm c hm lng st thp: nng t 0,4 - 10 mg/l

- Nc ngm c hm lng st trung bnh: t trn 10 n 20 mg/l.

- Nc ngm c hm lng st cao: nng trn 20 mg/l

Khi ngun nc c nng vt tiu chun cho php th chng ta phi tm cch khloi tr st.

Phng php oxy ha st:

Chuyn Fe (II) v Fe (III) v tch khi nc di dng kt ta Fe(OH)3.

Fe(HCO3)2 + 2H2O Fe(OH)2 + 2CO2 + 2H2O

4Fe(OH)2 + O2 + 2H2O 4Fe(OH)3

St (III) trong nc kt ta thnh bng cn mu vng, qua vic lng lc d dng tckhi nc.

Trong nc ngm nng oxy ha tan (DO) khng c hoc mc rt thp. Do tng DO trong nc ngm, bin php n gin nht l lm thong b mt. Hiu qulm thong c xc nh theo nhu cu oxy qu trnh kh st.

Kh st bng qu trnh oxy ha:


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-Lm thong n gin b mt lc: s dng gin ma ngay trn b mt lc. Chiu cgin phun 0,7m, l phun ng knh 5mm, lu lng ti 10 m3/h. Hm lng DOtrong nc sau lm thong khong 40% lng DO bo ha 25 C.

-Lm thong bng gin ma t nhin: s dng gin lm thong 1 hay nhiu bc vi sri x hay tre g, lu lng ti v chiu cao tng t nh trn. Hm lng DO tronc tng i cao, lng CO2 sau lm thong gim 50%.

-Lm thong cng bc: quy m hn dng thp ti, lu lng ti 30 -40 m3/h.Lng khng kh tip xc t 4 -6 m3/m3 nc. Hm lng DO sau lm thong t 7lng DO bo ha, lng CO2 gim n 75% so vi ban u.

i vi nc ngm c hm lng st thp th ch cn s dng cch lm thong n b mt lc l t yu cu. Sau qu trnh cung cp oxy cho nc, hn hp kh -ncqua lp vt liu lc. Thnh phn Fe (II), DO v 1 phn Fe(III) to thnh c tch r bm trn b mt vt liu to mng xc tc, qu trnh hp th cng nh oxy ha Fe tcht keo t v c gi li trn b mt vt liu lc. trnh hin tng tt lc t phn ny, nh k cn phi ra lc b mt hoc thay mi lp lc. i vi nc ng

hm lng st cao th cn b sung mt lng ha cht tng hiu qu qu trnh to bkeo t trc khi qua b mt lc.

Cui cng nc sch sau x l i ra ngoi v c thu gom s dng.

5. th ho nh hng nh th no n nhim nc?

Tr li:

- Nu th ho i km vi chnh sch bo v mi trng mt cch ng nth s khng nh hng ti mi trng nc, nc s khng b nhim.- Nu nh TH khng i km vi chnh sch bo v mi trng hp l th sgy nhim ngun nc. Tc TH cng nhanh th nhim mi trng nccng nng. c th :

+ nhim nc mt: TH s lm gia tng mt dn s, t lng rcthi thi vo mi trng s tng ln theo tc TH. TH s ko theo


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nhiu ngnh ngh pht trin, mi ngnh ngh s c mi loi cht thi ctrng, nh vy thnh phn cht nhim trong nc s tr nn phong ph v phc tp hn. Nc thi t sinh hot, cc c quan, bnh vin, khu cngnghip, khu ch xut khi khng c x l hoc x l khng trit s lm

cho nc b nhim, hm lng cc cht nhim, cc kim loi nng,BOD, COD v vi sinh vt gy bnh trong nc s tng cao lm nhimngun nc mt.

+ nhim nc ngm: Vic khai thc nc ngm qu mc phc v choqu trnh TH s khin cho mc nc ngm b h thp. Vic khoan, lpging khng ng k thut s khin nc nhim trn b mt ngm xunglm nhim nc ngm.

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