KHOA A L TRNG I HC KHOA HC T NHIN

M U1. Tnh cp thit ca tiVng ven bin c xem l khu vc c nhiu hot ng nng ng, c y cc hot ng kinh t, cng bin, cng nghip quan trng. y cng l khu vc c tc th ha nhanh chng vi gn 40% dn s th gii tp trung trong khong 100 km cch b bin, gp 2/3 ln vng ni a. Vit Nam, c tnh c 50% cc th ln nm tp trung khu vc ca sng ven bin nh H Long, Hi Phng, Nng, TP. H Ch Minh, B Ra Vng Tu cng vi khong 20% tng dn s c nc. Chnh s tp trung ny, m vng ca sng ven bin lun tim n nhiu nguy c nhim mi trng, tc ng n sc khe con ngi v cc h sinh thi ven bin. Nhiu cht thi c hi ca hot ng cng nghip, sn xut ca con ngi c thi vo mi trng m khng qua x l, gy nn tnh trng nhim gia tng.Hi Phng l mt thnh ph nm pha ng Bc Bc B, l mt trung tm kinh t ven bin ln nht c nc, l u mi giao thng quan trng pht trin kinh t - x hi cng nh an ninh quc phng ca khu vc Bc B. i ven bin Hi Phng c chiu di di trn 125 km vi 5 ca sng ln to ln cnh quan v h sinh thi a dng c nhiu tim nng v li th cho pht trin kinh t - x hi. Trong nhng nm gn y, vi mc ch pht trin kinh t, khu vc ven bin Hi Phng c khai thc ti a, dn n mi trng nc khu vc ven bin Hi Phng ang c xu hng b nhim nghim trng bi cc hot ng kinh t - x hi ca con ngi nh xy dng h cha trn thng ngun sng Hng, nui trng thy hi sn ven bin v c bit l sc p ca qu trnh th ha v s pht trin mnh m ca cng bin dn n vic x mt lng ln cht thi trc tip ra bin. Suy thoi mi trng nc khng ch nh hng ti i sng sinh hot ca ngi dn trong vng m cn lm gim gi tr du lch ca mt a im p trn t nc. Chnh v th, cn thit phi tin hnh cc nghin cu quan trc, nh gi nhanh v c hiu qu hin trng v bin ng cht lng mi trng nc khu vc ven bin thnh ph Hi Phng.Vin thm v GIS l mt trong cng c hu hiu quan trc v nh gi cht lng mi trng nc bi l t liu vin thm cung cp ci nhn tng quan trn mt vng rng ln, kh nng cp nht thng xuyn v gim bt chi ph trong nghin cu. T nhng nm 1970, hng lot nghin cu trn th gii c thc hin nhm pht trin phng php lp bn hin trng mi trng nc t t liu vin thm kt hp vi kho st thc a. Ngy nay, vi s h tr ca cc thit b o ph mt t v kho st thc a, cc thut ton x l nh vin thm lp bn hin trng mi trng nc ngy cng c ci tin v t chnh xc cao. Trn c s , ti s xem xt cc c im t nhin, a hnh, a mo ca khu vc ven bin thnh ph Hi Phng a ra nhng quy trnh tnh ton x l nh v tinh khc nhau gim st v nh gi cht lng mi trng nc ca khu vc trong giai on t 2000 - 2014. l l do sinh vin chn ti: ng dng vin thm v h thng tin a l nh gi s thay i cc thng s cht lng mi trng nc ven bin thnh ph Hi Phng giai on 2000-20142. Mc tiu nghin cung dng vin thm v h thng tin a l nhm xc nh v thnh lp bn cho mt s thng s cht lng nc, l c s quan trng cho vic nh gi cht lng mi trng nc cho khu vc Hi Phng giai on 2000 - 2014. T kt qu nghin cu, kt hp vi kin thc, s hiu bit ca sinh vin v khu vc, tnh ton, so snh v nh gi s bin ng mt s thng s cht lng mi trng nc khu vc nghin cu trong giai on ny.3. Nhim v ca ti- Tng quan tnh hnh ng dng Vin thm v GIS trong nghin cu cht lng mi trng nc trn th gii v Vit Nam.- X l nh vin thm tnh ton mt s thng s cht lng mi trng nc khu vc nghin cu nm 2000 v nm 2014.- nh gi s bin ng mt s thng s cht lng mi trng nc giai on nm 2000 -2014 lin quan n hot ng pht trin kinh t x hi ca thnh ph Hi Phng.4. i tng v phm vi nghin cu - i tng nghin cu ca kha lun: Cc thng s cht lng nc bao gm: Nhit , c, mn, clorophyll a vng ven bin thnh ph Hi Phng. nh gi s bin ng ca cc thng s s ny giai on 2000 - 2014 - Phm vi khng gian: Khu vc ven bin thnh ph Hi Phng,trong ranh gii vi t lin chnh l ni c mc chiu cao nht v ranh gii ngoi bin l khu vc c su 30m.- Phm vi thi gian: T nm 2000 n nm 2014, y l giai on m Hi Phng ang c s chuyn mnh mnh m trong pht trin cng nghip, cng bin v du lch.Ngoi ra, nhng hot ng khai thc t thng ngun cc con sng nh sng Hng, sng Thi Bnh, sng Cm din ra vi cng cao hn, iu ny dn n vic nh hng khng h nh ti Hi Phng, l h lu ca cc con sng ln ny.5. C s ti liu, d liuTrong kha lun, sinh vin s dng cc ti liu c lin quan nh sau:- nh v tinh Landsat nm 2000 v nm 2015. nh Landsat 7 c chp ngy 15 thng 8 nm 2000 v nh Landsat 8 c chp ngy 23 thng 7 nam 2014. Sinh vin chn nh c cng thi im vo ma h, c nhiu tng ng v c im iu kin t nhin cng nh cc hot ng kinh t so snh, nh gi nhm cho kt qu c chnh xc cao nht.- Cc ti liu v iu kin t nhin, ti nguyn thin nhin v kinh t x hi, cc s liu o c, tnh ton, bn lin quan n cht lng mi trng nc ven bin ti mt s c quan, ban nghnh nh:+ Vin Ti nguyn v Mi trng bin+ S Ti nguyn v Mi trng Hi Phng+ S Khoa hc v Cng ngh Hi Phng- Cc ti liu lin quan n cc thng s ca cht lng mi trng nc Hi Phng, cc cng trnh nghin cu v cc ch s cht lng mi trng nc c cng b trong nc v quc t nh:+ nh gi hin trng mi trng v xc nh cc vn u tin qun l tng hp vng bin Hi Phng.+ Hin trng cht lng mi trng nc vng ven b t Qung Ninh n Qung Bnh 2013 ( Khoa hc Cng ngh Bin, tp 14, s 3A, tr 76 )..6. Phng php nghin cu- Thu thp v phn tch s liu, d liu: Ti liu tham kho c thu thp t cc c quan ban nghnh ca Trung ng v a phng, cc vin nghin cu, cc trng i hc trong c nc c lin quan n vn nghin cu c phn tch v la chn phc v cho mc tiu nghin cu ca ti.- Phng php Vin thm: Phng php vin thm c s dng x l nh Landsat chp t cc thi gian khc nhau, t tnh ton cc ch s mi trng nc.- Phng php GIS: p dng kh nng phn tch khng gian ca GIS tch hp cc kt qu x l nh vin thm xc nh s bin ng cc thng s cht lng mi trng nc.7. ngha khoa hc v thc tinV mt khoa hc: gip sinh vin hiu bit v cc ch tiu ca mi trng nc v bn cht bin ng ca ca cc ch tiu khu vc ven bin. Bn cnh kt qu ca kha lun cn gp phn xy dng c s khoa hc v phng php lun, cho php nh gi kh nng ng dng Vin thm v GIS trong nghin cu khu vc ven bin. V mt thc tin: vic p dng cng ngh mi gp phn tit kim thi gian v chi ph cho vic theo di, nh gi bin ng. Kt qu ca kha lun l ti liu b ch cho cc nghin cu khc, ng thi cho php nghin cu cc bin php nhm bo v mi trng nc.8. B cc ca Lun vnNgoi phn m u v kt lun, lun vn bao gm 3 chng vi cc ni dung nh sau: Chng 1: Tng quan v iu kin t nhin v iu kin kinh t - x hi ca Hi Phng nh hng n cht lng mi trng nc ven bin Hi PhngChng 2: Phng php nghin cu cht lng mi trng nc ven bin Hi PhngChng 3: ng dng Vin thm v GIS nghin cu v nh gi s thay i cht lng mi trng nc khu vc ven bin Hi Phng

35

CHNG 1: TNG QUAN V IU KIN T NHIN KINH T X HI NH HNG N CHT LNG MI TRNG NC VEN BIN HI PHNG 1.1 Tng quan v cht lng mi trng nc v cc tiu chun cht lng nc ven bin1.1.1 Tng quan v cht lng mi trng ncNc l ti nguyn ht sc quan trng i vi s sng ca con ngi v thin nhin, tham gia thng xuyn vo cc qu trnh sinh ha trong c th sng. Phn ln ca cc phn ng ha hc lin quan n s trao i cht trong c th u c dung mi l nc. Nh c tnh cht ny m nc tr thnh tc nhn mang s sng n cho tri t. V vy, con ngi lun phi quan tm n cht lng mi trng nc.Ty vo tng loi nc vi mc ch s dng khc nhau, s c mt s tiu chun ng vi tng mc ch s dng. Tuy nhin, mt s thng s c bn c s dng trong nh gi cht lng mi trng nc nh sau:- Cc ch tiu vt l.+ Nhit Nhit ca nc t nhin ph thuc vo iu kin kh hu thi tit hay mi trng ca khu vc. Nhit nc thi cng nghip c bit l nc thi ca nh my nhit in, nh my ht nhn thng cao hn t 10 25oC so vi nc thng.Nc nng c th gy nhim hoc c li ty theo ma v v tr a l. Vng c kh hu n i nc nng c tc dng xc tin s pht trin ca vi sinh vt v cc qu trnh phn hy. Nhng nhng vng nhit i nhit cao ca nc sng h s lm thay i qu trnh sinh, ha, l hc bnh thng ca h sinh thi nc, lm gim lng xy ha tan vo nc v tng nhu cu xy ca c ln 2 ln. Mt s loi sinh vt khng chu c nhit cao s cht hoc di chuyn i ni khc, nhng c mt s loi khc li pht trin mnh nhit thch hp.+ Mu scNc c th c mu, c bit nc thi thng c mu nu en hoc nu. Mu ca nc thng c phn thnh hai dng; mu thc do cc cht ha tan hoc dng ht keo; mu biu kin l mu ca cc cht l lng trong nc to nn. Trong thc t ngi ta xc nh mu thc ca nc, ngha l sau khi lc b cc cht khng tan. C nhiu phng php xc nh mu ca nc, nhng thng dng l phng php so mu vi cc dung dch chun l clorophantinat coban.+ c c ca nc do cc ht l lng, cc cht hu c phn hy hoc do gii thy sinh gy ra. c lm gim kh nng truyn nh sng trong nc, nh hng kh nng quang hp ca cc sinh vt t dng trong nc, gy gim thm m v lm gim cht lng ca nc khi s dng. Vi sinh vt c th b hp ph bi cc ht rn l lng s gy kh khn khi kh khun. c cng cao nc nhim bn cng ln.+ Mi vNc sch l nc khng mi v. Khi bt u c mi th l biu hin ca hin tng nhim. Trong nc thi mi rt a dng ty thuc vo lng v c im ca cht gy nhim.- Cc ch tiu ha hc v sinh hc.+ pH.Gi tr pH ca nc thi c ngha quan trng trong qu trnh x l. Gi tr pH cho php ta la chn phng php thch hp, hoc iu chnh lng ha cht cn thit trong qu trnh x l nc. Cc cng trnh x l nc bng phng php sinh hc thng hot ng pH t 6,5 9,0. Mi trng ti u nht vi khun pht trin thng l 7 8. Cc nhm vi khun khc nhau c gii hn pH khc nhau.+ Ch s DO (Disolved Oxygen)DO l lng oxi ha tan duy tr s sng cho cc sinh vt di nc. Bnh thng oxi ha tan trong nc khong 8 10 mg/l, chim 70 80 % khi oxi bo ha. Mc oxi ha tan trong nc t nhin v nc thi ph thuc vo mc nhim cht hu c, cc hot ng ca th gii thy sinh, cc hot ng ha sinh, ha hc v vt l ca nc. Trong mi trng nc b nhim nng, oxi c dng nhiu cho cc qu trnh ha sinh v xut hin hin tng thiu oxi trm trng.+ Ch s BOD (Nhu cu oxy sinh ha - Biochemical Oxygen Denand).Nhu cu oxy sinh ha hay l nhu cu oxy sinh hc thng vit tt l BOD, l lng oxy cn thit oxy ha cc cht hu c trong nc bng vi sinh vt (ch yu l vi khun) hoi sinh, hiu kh. Qu trnh ny c gi l qu trnh oxy ha sinh hc.+ Ch s COD (Nhu cu oxy ha hc - Chemical oxygen Demand)Ch s COD l lng oxy cn thit cho qu trnh oxy ha ha hc cc cht hu c trong nc thnh CO2 v H2O bi mt tc nhn oxi ha mnh. COD biu th lng cht hu c c th oxy ha bng con ng ha hc. + Ch s v sinh (E - Coli).Trong nc thi c bit l nc thi sinh hot, nc thi bnh vin, nc thi vng du lch, dch v, khu chn nui v.v nhim nhiu vi sinh vt c sn trong phn ngi v phn xc vt. Trong c th c nhiu loi vi khun gy bnh c bit l bnh v ng tiu ha, nh t, l thng hn, cc vi khun gy ng c thc phm.E - coli l vi khun ph bin trong nc thi, n c th sng trong iu kin khc nhit ca mi trng ngoi cng nh trong phng th nghim. Chnh v vy ngi ta chn E - coli l ch tiu nh gi cht lng nc thi.1.1.2. Tiu chun cht lng nc bin ven bNm 2008, B Khoa hc, Cng ngh v Mi trng ban hnh tiu chun nc bi ven b: TCVN 10: 2008. Tiu chun ny gii hn cc thng s v nng cho php cc cht nhim trong nc bin ven b v dng nh gi cht lng nc ca cc vng nc bin ven b.Theo TCVN 10: 2008, nc bin ven b c phn thnh 3 loi s dng: nc bi tm, nc nui thy sn v nc cc ni khc. ng vi mi loi nc bin ven b s c tiu chun gi tr gii hn nng cc cht nhim khc nhau Di y cho mt s Bng 1.1: Mt s tr s ca tiu chun nc bin ven b (QCVN 10: 2008/BTNMT)TTThng sn vGi tr gii hn

Bi tm, th thao di ncNui thy sn, bo tn thy sinhCc ni khc

1xy ha tan (DO )mg/l 4 5-

2Nhit oC3030-

3 Tng cht rn l lng ( TSS)mg/l5050-

4Asen mg/l0,040,010,05

5Ch ( Pb)mg/l0,020,050,1

6 Thy Ngn (Hg)mg/l0,0020,0010,005

7pH6,5 8,56,5 8,56,5 8,5

Tiu chun nc nc thi chy vo nc bin ven bTheo Quyt nh s 22/2006/Q-BTNMT, ngy 18 thng 12 nm 2006 ca B Ti nguyn v Mi trng v vic bt buc p dng tiu chun Vit Nam v mi trng trong quy nh vic p dng tiu chun TCVN 5945:2005-Tiu chun nc thi cng nghip. i vi ngun tip nhn nc thi cng nghip l vng nc bin ven b th gi tr h s Kq=1,2. i vi ngun tip nhn nc thi cng nghip l vng nc bin ven b dng cho mc ch bo v thy sinh; th thao v gii tr di nc th gi tr h s Kq=1, vi Kq l h s lu lng/dung tch ngun tip nhn nc thi [12]. 1.2.Tng quan v cc iu kin t nhin kinh t x hi nh hng n cht lng mi trng nc ven bin Hi Phng1.2.1. iu kin t nhina. c im t nhinHi Phng l mt thnh ph ven bin, thuc vng ng Bng sng Hng v vng kinh t trng im Bc B, cch th H Ni 102 km. Lnh th chnh ca Hi Phng nm trong phm vi to a l t 20o3039 n 20o0115 v Bc v t 10602339 n 10700839 Kinh ng. Trung tm thnh ph to 106o40 kinh ng 20o50 v Bc; Pha Bc gip tnh Qung Ninh; Pha Nam gip tnh Thi Bnh; Pha Ty gip tnh Hi Dng; Pha ng gip Vnh Bc B [14] Din tch t nhin l 1.507,57 km2, Tnh n thng 12/2011, dn s Hi Phng l 1.907.705 ngi v 14 n v hnh chnh, 5 qun Hng Bng, L Chn, Ng Quyn, Kin An, Hi An; th x Sn v cc huyn [14]

Hnh 1.1 : Bn thnh ph Hi PhngVi v th nm trn nhiu trc ng giao thng quan trng ca c nc v quc t, Hi Phng hi t y cc li th v cng bin, giao thng ng bin, ng sng, ng st, ng b, hng khng, l ca ng ra bin quan trng ca min Bc v c nc, giao lu thun li vi cc tnh trong c nc v cc quc gia trn th gii. Cc quc l 5, 10, ng st, cc tuyn bin l nhng mch mu chnh gn kt quan h ton din ca Hi Phng vi cc tnh khc trong c nc.b. a hnh, a moc im a hnh rt a dng: sng ngi, i ni, ng bng, bin v vng ca sng... Mng li sng ngi ca Hi Phng dy c thuc mng li sng Thi Bnh, hng chy ch yu l Ty Bc-ng Nam, un khc ln, bi sng rng. Bin l yu t a l t nhin ni bt ca Hi Phng. Trong tng din tch hn 5.000km2 ch c 1.507km2 t ni, hi o chim trn 300km2. Vng nc bn ngoi ng b bin Hi Phng l mt di hp, rng khong 31km, su khng qu 40m, bao quanh h qun o ven b Ct B, Thng Mai, H Mai, Long Chu, Hn Du. Bin Hi Phng c ch nht triu: trong na thng c ti 11 ngy xut hin nht triu, mc nc triu ln nht t 4,0m Hn Du, khi c bo c th t ti 5-6m[14].Vng ca sng v ven bin: Hi Phng c b bin di 132km, c cc ca sng Vn c, ca Nam Triu, ca sng Thi Bnh; v cc h sinh thi rng ngp mn, h sinh thi ca sng, h sinh thi ven bina hnh Hi Phng c xu hng thp dn v pha Nam vi 4 kiu sau: a hnh caster ( vi), a hnh i ni thp, a hnh i ni v ng bng.[14]Do a hnh nhiu i ni, c hng thp dn v pha ng nam, kt hp vi cc hot ng t thng ngun lm mt lp ph thc vt, nn hng nm, nht l vo ma ma, lng t ra tri theo nc ma trn xung vng nc ven bin rt ln, lm gia tng ng k hm lng cht rn l lng v kim loi nng trong nc.c. Kh huKh hu ca thnh ph Hi Phng mang tnh cht c trng ca kh hu min Bc Vit Nam: nng m, ma nhiu, c 4 ma Xun, H, Thu, ng tng i r rt, nhng c th chia thng 2 ma ln xt v mt nhit v lng ma Mt ma ng lnh v kh t thng 11 ti thng 4 nm sau vi nhit trung bnh l 20,3oC; Ma h, nm mt v ma nhiu t thng 5 n thng 10 vi nhit trung bnh vo khong 32,5oC. Do nm st bin nn vo ma ng, Hi Phng m hn 1oC so vi H Ni. Nhit trung bnh trong nm t 23oC ti 26oC. Thng nng nht vo thng 6 v 7, nhit c th ln n 44oC v thng lnh nht vo thng 1 v 2, nhit c th xung di 5oC. m trung bnh nm vo khong 80-85%, cao nht vo thng 7,8,9 v thp nht l thng 1 v thng 12.[14]Lng ma trung bnh t 1600 1800 mm/nm. Lng ma ch yu tp trung vo cc thng trong ma h t thng 5 n thng 10. Thng c lng ma cao nht l thng 8 vi lng ma trung bnh xp x 350mm.Lng ma trong cc thng ma ng t thng 11 n thng 4 l kh nh. Thng c lng ma thp nht l thng 1 vi lng ma trunh bnh di 30mm.[14]Vi lng ma nhiu ti khu vc, ma mang theo nhiu bi thi do cc nh my thi ra, c bit l bi kh CO2, d gy ra hin tng ma axit, chy xung cc sng v em ra bin, l nguyn nhn gin tip lm nh hng n cht lng mi trng nc ven bin thnh ph Hi Phng.d. Ch thy vn, hi vn c im thy vn Hi phng c nhiu sng ln chy qua, cc sng ny u l phn h lu cui cng trc khi ra bin ca h thng sng Thi Bnh. Hng chy ca cc dng sng ch yu l ty bc ng nam, un khc ln, bi sng rng, ph sa bi p ngy cng nhiu, nht l vng ca sng, vi on hnh thnh cc doi bi hay cn ct. Cc sng ln c ca trc tip ra bin va chu nh hng ca ch dng chy thng ngun, va chu nh hng ca ch thy triu vnh Bc B; cng gn ca sng, long sng cng m rng, hai b c bi p nhiu. Tuy nhin, trong thi gian gn y, mt s vng ca sng lng ng ph sa c chiu hng b thu hp, gy kh khan cho giao thng thy v thay i cu trc dng.Bng 1.2: Cc c trng c bn mt s sng chnh Hi Phng[11]Tn sngChiu di (km)Chiu rng trung bnh (m) su trung bnh (m)Tc dng chy trung bnh (m/s)

Bch ng42100080.7

Cm3740070.7

Vn c3840081.2

Thi Bnh3015030.4

Luc1812040.8

Lch Chay4312040.7

c im hi vnThy triu: Vng ven bin v o Hi Phng l nht triu thun nht vi bin dao ng. Thng thng trong ngy cut hin 1 nh triu (nc ln) v mt chn triu ( nc rng ). Trung bnh trong mt thng c 2 k triu cng, mi chu k ko di 11-13 ngy vi bin dao ng mc nc t 1-4m. Trong k triu km tnh cht nht triu gim i r rt, tnh cht bn nht triu tng ln: trong ngy xut hin 2 nh triu (cao, thp). Hng nm thy triu c bin ln vo cc thng 5,6,7 v 10,11,12 bin nh vo cc thng 3,4 v 8, 9. Ma ng triu thp vo ban ngy, ma h triu thp vo ban m. [6]Sng bin: Trn vng bin khi Hi Phng, hng gi thnh hnh nht l hng gi ng bc, tn sut t thng 9 ti thng 4 l 33.5% ti 62.0%. Sng ven bin Hi Phng ch yu l sng truyn t ven bin ngoi khi b khc x v phn tn nng lng do ma st y. Ma h t thng 5 n thng 8, sng hng nam khng ch trn ton vng bin, tn xut ln ti 43%. Thng 7, tn xut sng hng ng chim ti 18%. T thng 10 nm trc ti thng 3 nm sau, hng sng thnh hnh trn vng bin pha bc o Ct B l ng bc, tn sut ln hn 40%, vng pha nam o Ct B Long Chu, sng chuyn dn sang hng ng, thng 3 sng hng ng thnh hnh nht.Hng ca sng bin c vai tr quan trng trong vic phn b hm lng cc cht trong nc, nu tc dng ca sng bin theo hng no thnh hnh th vng phn b ca cc cht s nhiu v ch yu theo hng y.[6]Dng chy ven binDng chy ven b Hi Phng l dng chy tng hp, gm cc thnh phndng chy triu, gi, sng, dng chy sng v c nhng tnh cht ca dng chyvnh Bc B. Dng chy cc khu vc ca sng thng chu nh hng mnhca sng, trong khi pha ngoi bin dng chy tng mt ch yu do gi gy ra. Cc sng ln chy qua Hi Phng u chy theo hng ty bc ng nm, un khc ln, l h lu cui cng trc khi ra va chu nh hng ca ch dng chy thng ngun, va chu nh hng ca ch thy triu, dng chy nen b nn cc ch s ca mi trng nc ven bin Hi Phng b nh hng v bin i rt khc so vi mi trng nc trong lc a cng nh mi trng nc ngoi bin.[6]1.2.1. iu kin kinh t- x hia. Dn s v lao ng Theo s liu thng k nm 2013, Hi Phng c s dn trung bnh l 1.925,2 nghn ngi, vi din tch l 1.527,4 km2 th mt dn s y l 1.260,0 ngi/km2, tng s lao ng ton thnh ph l 1.384.673 ngi.[16]Mt dn s cao dn n vic lm qu ti lng nc thi cha c x l ra cc con sng v ra bin. Ngoi ra, c nhiu h gia nh nui trng thy hi sn ven bin th cht thi v nc thi thng x trc tip xung nc. y l 1 trong cc nguyn nhn chnh gy ra nhim ngun nc ti vng ca sng ven bin. b. c im pht trin kinh tTc tng tng sn phm trong nc (GDP) bnh qun trong 5 nm 2001 - 2005 t 11,05%, gp gn 1,5 ln mc tng bnh qun ca c nc, GDP nm 2005 t 20.846,9 t ng (tng ng 14.071,9 t ng theo gi so snh 1994). C cu kinh t chuyn dch theo hng gim dn t trng nng- lm, tng t trng ca ngnh cng nghip - xy dng v dch v.[7] c im pht trin mt s nghnh c tc ng mnh ti mi trng bin Cng nghip - Pht trin cng nghip: Gi tr sn xut cng nghip c tc tng trng cao, t 1996 2000 tng bnh qun 23,65%, t nm 2001 2005 tng 19,91%, trong cng nghip Trung ng tng bnh qun l 27,26%, cng nghip a phng 26,75% v cng nghip c vn TNN l 16,88%. Gi tr sn xut cng nghip trn a bn thnh ph 9 thng u nm 2006 c t 17.998,8 t ng, tng 18,7% so vi cng k, t 70,5% k hoch nm.[14] Nng nghip- Mt s ch tiu chung: Trong giai on t nm 2001 2005 tc tng chung ton ngnh l 3,96 % trong : tc pht trin ca ngnh trng trt l 1,69%, ca chn nui l 8,81%; gi tr sn xut nng nghip ton ngnh nm 2005 t 2.267,7 t ng, tng 1,21 ln so vi nm 2000. Gi tr sn xut nng nghip tng lin tc qua cc nm; nm 2005 l 2.267,7 t ng, gp 1,035 ln nm 2004; tc pht trin nm sau so vi nm trc theo chiu hng tng dn t 3 -5%. C cu ngnh nng nghip nm 2005: t trng ngnh trng trt l 63,79%, chn nui l 33,77% v dch v nng nghip l 2,44%. Thu sn- Gi tr sn xut ngnh thu sn: lin tc tng trong giai on 2000 2005, nm 2000 gi tr sn xut ton ngnh l 326,0 t ng, tc tng sn lng khai thc thu sn khong 7,5%/nm; nm 2005 tng ln 699,4 t ng; trong nh bt v nui trng thu sn chim ch yu, dch v thu sn chim t l rt nh, 0,57% (nm 2005). - Din tch nui trng thu sn: Tnh n thng 10/2005 din tch nui trng thy sn mn l a vo sn xut l 8.259 ha chim 61,51%, din tch nc ngt a vo sn xut l 5.168 ha chim 38,49% tng din tch nui. Tiu th cng nghip v lng nghHin ti Hi Phng c cc loi hnh lng ngh truyn thng nh: Th cng m ngh, ch bin nng sn: bn, bnh a, bnh gai, ch bin g, sn xut kim khTrong , mt s lng ngh vi cc sn phm chnh cc a phng nh: ngh c kim loi M ng (Huyn Thu Nguyn); tc tng Vnh Bo, ch bin nc mm Ct Hi, dt vi tm C Am Vnh Bo, ngh lm mui Bng La - Sn,... Thng mi v dch v- Thng mi: Hot ng thng mi ngy cng thu ht nhiu lao ng, to ra gi tr sn xut ngy cng tng, gp phn gii quyt nhiu vic lm v nng cao i sng ca ngi dn. Tng kim ngch xut khu nm 2005 l 839.029 nghn USD, tng 2,68 ln so vi nm 2000, trong kinh t a phng chim t trng ln nht, 52,6% .[14]- Du lch: Doanh thu t hot ng du lch tng lin tc, v tng nhanh, nm 2000 l 276.464 triu ng, nm 2005 con s ny l 1.656.824 triu ng, thu ht nhiu lao ng v nng cao ng k i sng ngi dn. Nm 2005 s khch quc t n Hi Phng l 478.077 lt, tng 2,41 ln so vi nm 2000. Trong , o Ct B v Sn l cc trung tm du lch ca Hi Phng. 9 thng u nm 2006, du lch thnh ph Hi Phng c t trn 2,3 triu khch, tng 27,6% so vi cng k.[14] nh hng ca iu kin kinh t ti mi trng nc ven bin Hi PhngTheo n qun l tng hp ti nguyn bin o ca S Ti nguyn-Mi trng,mi nm, chng ta thi ra sng, bin hng nghn tn cht thi sinh hot, nhin liu, cn du, nc ra tu ln cht thi rn, mt kim loi, sn v cc cht ty ra trong qu trnh hot ng. Bin Hi Phng hng chu khong 657-820 nghn tn/ngy m, lng cht thi t cc vng ni a v ven b ng bng sng Hng; nc thi cng nghip t H Ni v cc tnh thng ngun, trong c tnh trong nc thi ca khu Vit Tr c khong 100 tn H2S04, 40 tn HCl, 300 tn Ben-zen lm nhim nng vng bin Hi Phng.[17]Ngun thi t lc a ra bin chim t 60% - 70% nhim bin. Ti vng b Hi Phng, ngun thi t lc a bao gm cc ngun ch yu sau: - Ngun thi sinh hot: Vi dn s trn 1 triu ngi, tp trung ch yu ti cc khu th ven bin v lng khch du lch t 3 - 4 triu lt/nm tp trung ch yu khu vc Hi Phng Ct B to ra ngun thi sinh hot rt ln. Bn cnh , c mt s bi rc ven sng, ven bin ( bi rc Trng Ct) cha c thit k ph hp, cha c h thng thu gom x l nc r rc cng l ngun b sung ng k cc cht nhim cho vng bin ven b Hi Phng. - Ngun thi cng nghip: Hi Phng v Qung Ninh l cc a phng c gi tr sn xut cng nghip rt ln. Tnh n thng 10/2009, Qung Ninh v Hi Phng c 9 khu cng nghip ven bin (Ci Ln v Ci Ln m rng, Hi Yn, Vit Hng, Nomura, nh V, An Dng, Sn, Nam Cu Kin, Trng Du). Ngoi ra, trong vng cn l ni tp trung rt nhiu cc c s sn xut cng nghip ri rc. Ngun nc thi cng nghip ch yu pht sinh t ngnh cng nghip ch bin lng thc, thc phm, sn xut ung vi hm lng cao cc cht hu c v dinh dng. Hi Phng c hng chc c s ng tu v sa cha ln, cc c s sn xut phn bn, ch bin thp, vt liu xy dng, cc kho, cng xng du, c bit l khu cng nghip nh V, nm st khu vc ca Cm ang ngy m hot ng. Bi vy, ti cc khu vc ny, nng du v cyanua trong t ngm ra sng bin kh cao. - Ngun thi t sn xut nng nghip: Bao gm d lng cc loi phn bn ho hc, ho cht bo v thc vt, lng cht thi t hot ng nui thu sn ven bin. Gn y, nh hng c nc ven b tng ln r rt khu bi tm Sn v nam Ct B. l kt qu ca nn ph rng ngp mn lm m nui thu sn gy ra xi l b vng ven binNgoi ra, nhim nc bin cn do cc hot ng hng hi ti cc cng bin Hi Phng. Theo Cng v Hi Phng, 3 nm tr li y, lng tu ra vo cng bin lun lun tng. Theo Quy chun k thut quc gia v cht lng nc mtdng trong giao thng ng thy v cc mc ch khc, yu cu nc mt ln du, m cho php ch l 0,3 mg/l.Va qua, bo co ca S TN&MT Hi Phng cho thy, hm lng du trong nc vng b Hi Phng hin kh cao, trung bnh 0,4 mg/l, dao ng trong khong t 0,1 - 1,1 mg/l.Cc khu vc c hm lng du cao lmt nc khu vc cng Hi Phng c nhim du t 0,3 - 0,6mg/l vt tiu chun cho php. Vng ven b qun Hi An, huyn Kin Thy, hm lng du trung bnh khong 0,6mg/l. Khu vc ca sng Bch ng, kt qu kho st trong nhiu nm cho thy nng du c xu hng tng cao, c bit khu vc trong sng, ni gn bn cng, nht l khu vc S Du.

Hnh 1.2 : Hot ng tu thuyn ti bn cng khu vc ven ca Bch ng.Ti khu vc Sn, giai on t nm 2009-2012, nng du m lun vt gii hn theo quy chun ASEAN (0,16mg/l), thm ch vt gii hn cho php (theo quy chun Vit Nam 08:2008/BTNMT)l 0,3 mg/l.Nguyn nhn dn n tnh trng trn l do hot ng ca cc loi tu nh bt hi sn, tu du lch, tu qun s thng xuyn ra tu, x thi du my, nc dn tu, ra lung tu.[15]1.3.Hin trng cht lng mi trng ven bin Hi PhngVng ca sng ven bin Hi Phng c s dng cho nui trng thu sn, giao thng, du lch, pht trin cng... Song hin nay, mi trng bin ti cc vng ca sng ven bin ang b nhim.- Nhit : dao ng t 13,60C - 17,50C, nhit thp nht o c ti ven bin Kin Thu v cao nht o c ti ven bin huyn o Bch Long V.[9]- Gi tr pH: dao ng t 7,27 - 8,11, pH thp nht o c ti ven bin Sn v cao nht o c ti ven bin huyn o Bch Long V. Gi tr pH ti cc khu vc ven bin Hi Phng khi so snh vi QCVN 10:2008/BTNMT u nm trong gii hn cho php.[16]- c: c trong khu vc ma l kh ln, c gim dn t sng ra bin. Nguyn nhn lm tng c ch yu do ngun bi tch trong sng a ra v do xi l. Khu bi tm Sn c c cao.[9]- Nng Oxy ho tan (DO): Vng bin Hi Phng c DO mc trung bnh khong 3,3 10,9 mg/l vo ma kit v khong 0,1 6,1 mg/l vo ma l. Ti ca sng DO cao hn pha trong sng khong 8,6 10,9 mg/l.[9]- COD: C gi tr dao ng t 0,2mg/l - 9,8mg/l, gi tr thp nht o c ti vng ven bin Ct B v cao nht o c ti vng ven bin Bch Long V (gn ca u tu). COD ti cc khu vc ven bin nh Hi An (khu vc Nam Hi), Kin Thy (x i Hp gip Bng La), Sn, Tin Lng (khu vc x Vinh Quang v Bch Long V vt QCVN 10:2008/BTNMT (NTTS).[9] - Nhu cu Oxy sinh ho (BOD): Vng bin Hi Phng nhn chung cha b nhim hu c, nng BOD5 khong t 1 3mg/l, vo thng 6 u ma l BOD5 c gi tr 13,6 31 mg/l, trung bnh khong 15 25 mg/l.[9]- Nitrit (NO2-): Nng nitrit trong nc vng b bin Hi Phng trong khong 11,4-52,2 g/L) v thp hn v ma ma (24-44).[1].So vi TCVN 5942-1995 quy nh cho nc mt (10g/L), nng nitrit trong nc vng b bin Hi Phng cao hn trung bnh 2-4 ln nhng thc t cha h xy ra hu qu sinh thi vc nc[9].- Cht rn l lng: Gi tr TSS thp nht o c ti ven bin huyn o Bch Long V (cch b 200m) v gi tr cao nht o c khu vc ven bin Sn (khu 1). TSS vng ven bin khu 1 Sn cng vt gii hn cho php ca QCVN 10:2008/BTNMT[9].Hm lng cht rn l lng (SS) trong nc vng b bin Hi Phng thay i trong khong rng, 33-212 mg/L tng mt v 37-222 mg/L tng y v thay i rt ng k theo ma.Bng 1.3: Nng cht rn l lng trong nc vng b bin Hi Phng nm 2006[18] n v: g/LTTKhu vcMa khMa maTrung bnh

MtyMtyMty

1Bc Sn Ca Lch Huyn337361634750

2Nam Sn Ca Vn c71131212222414176

3Nam Sn Ca Thi Bnh99157119153109155

- D lng ho cht bo v thc vt (BVTV): d lng ho cht BVTV trong nc vng Sn rt thp so vi gii hn cho php i vi nc bin ven b (10-50 g/L), ch t tng 0,566 g/L [1].- Kim loi nng: + Ch: hm lng ch trong nc vng b bin Hi Phng tng i thp, trong khong 1-21 g/l, trung bnh 2 g/l v ma ma, 4 g/l v ma kh v 3 g/L cho c nm.[9]+ Km: hm lng km trong nc vng b bin Hi Phng kh cao, trong khong 10-300 g/l, trung bnh 140 g/l, nhng cao hn cc khu vc xung quanh nh H Long v c th t cc i 800 g/l. Gi tr cc i vt 8 ln so vi TCVN 5943-1995 i vi bi tm v vt 800 ln i vi khu nui trng thu sn.[1] - Nhim bn du: Hin nay hm lng du trong nc vt gii hn cho php i vi nui trng thu sn (0,3mg/l), in hnh l Bn Bnh t 0,8 1,2 mg/l, bn My chai t 0,8 1,1 mg/l, bn ph Rng 0,6 1,0 mg/l v khu vc Sn 0,25 0,8 mg/l, khu ng nam Ct B khong 0,3 mg/l.[9]- Ch s Coliform: u vt tiu chun cho php do cc hot ng cng nghip, nc nc thi ni thnh, nc thi khu du lch Sn u ra sng, ra bin khng qua h thng x l.[9]- nhim do cht thi rn: rc thi t cc tu thuyn, nui trng hi sn, nhiu h dn c sng ven sng bin c thi quen rc xung sng, xung bin. - Cht lng nc bin ven o Ct B, Ct Hi, huyn Kin Thu, th x Sn bng Bng 1.4: Phn tch cht lng nc ven b nm 2006 [9]im thu muB1B2B3B4B5B6B7B8B9B10

pH8,17,98,18,18,18,08,18,27,97,8

TDS (mg/L)28300278001870022400217002120022500212001950019100

SS (mg/L)8111020125339350370250820750

mui ()29,0029,2019,5023,3022,6022,0021,521,219,218,70

c (NTU)111127421816335709578450415

NO3-N (mg/L)0,630,560,470,330,330,050,350,250,480,55

CL- (mg/L)1860018610116001440012000132001540145013151275

Tng P (mg/L)0,320,340,520,100,310,250,220,350,480,52

Fe (mg/L)0,110,100,160,370,320,280,150,180,220,17

DO (mg/L)5,96,08,07,77,66,86,56,85,15,2

BOD (mg/L)2249664577

Ghi ch: im B1: Bi tm Ct C Ct B (b ng).im B2: Bi tm Ct C Ct B (b Ty)im B3: Bi tm Vn Hng Th x Sn, khi triu xung thp.im B4: Bi tm khu I - Th x Sn, khi triu xung thp.im B5: Bi tm khu I - Th x Sn, khi triu xung thp.im B6: Bi tm khu I Th x Sn.im B7: Bi tm khu II Th x Sn.im B8: Bi tm khu II Th x Sn (b Ty bn o Sn).im B9: Bi tm khu III Th x Sn (b Ty bn o Sn).im B10: Bi tm khu III Th x Sn (b Ty bn o Sn).Cht lng mi trng ti cc bi tm u c hm lng cht rn l lng, hm lng vi sinh cao vt tiu chun cho php nhiu ln tr bi tm Ct C; cc ch tiu N-NH4+, NO3-, NO2, phospho tng, BOD5, DO u t tiu chun cho php; cha c du hiu nhim hu c, nhim do kim loi nng. Mi trng vng bin ngoi khi ( su trn 6 m nc)Cht lng nc vng bin trn 6 mt nc ti bin Ct B:- Nhit : trung bnh 19,50 C- c100 mg/l v gim dn ra ngoi khi trung bnh 80 mg/l- pH: kim yu khong 7,5-8,5- Nhim bn du: vng bin b nhim bn du, vng ven Ct Hi l 0,3 mg/l vo ma ma v 0,6 mg/l vo ma kh, vng Lch Huyn v Nam Ct B c nhim bn du t hn ma ma: 0,1 mg/l v vo ma kh 0,2 mg/l.- Tng Nit nh hn tiu chun cho php, cha b nhim hu c; NH4+ c gi tr t 0,001 -0,5 mg/l, ma l: 0,1 -0,2 mg/l, ma kit nh hn 0,05 mg/l; Nitrat: 0,01 2,35 mg/l, vo ma l: 0,1-0,3 mg/l v ma kit: < 0,1 mg/l; Nitrit c s thay i ngc vi NH4+ v NO3-, ma l: 0,01-0,05 mg/l v ma kit: 0,1-0,3 mg/l.- Nhm cc yu t kim loi nng: Fe, Zn, Cu, Al, As, Hg c nng thp, bin i theo khng gian v thi gian nh, c xu th gim dn t gn b ra bin v ma kit c nng ln hn ma l.Mi trng ca vng ven bin Hi Phng ang c nhng bo ng v nhim. Theo kt qu phn tch, iu tra kho st, khu vc nc bin ven b thuc vng bin Hi Phng, c bit l khu vc ca sng c cng, ang b nhim. S nhim trc tin phi k n l nhim du, hm lng du trong nc vng bin ven b Hi Phng c xu hng tng cao trong cc khu vc ca sng, gn khu vc cng, bn tu thuyn, c khu vc du lan vo cc khu m nui trng thu sn bm vo l s vt v ngm vo trm tch mt y. H s nhim du trong trm tch tng t 0,4 (nm 1995) ln 2,4 (nm 2000). nhim du ch yu do tnh trng pht trin giao thng thu, cng nghip v do cc phng tin ti thuyn nh c lc hu... v thiu trang thit b cng nh kh nng ng cu, x l nhanh khi c s c trn du. nhim c nc ng th hai sau nhim du. Gn y nh hng c ca nc ven b Hi Phng tng ln r khu vc bi tm Sn v ng Nam Ct B, lm bn nc, thit hi ti du lch v lm cht san h, gim nng sut s cp thc vt ni do hn ch quang hp. y l kt qu ca nn ph rng u ngun v xi l ven bin. Ch tnh ring sng Cm t 1960 n 1992, lu lng nc tng bnh qun hng nm t 1 km3/nm ln 12,9 km3/nm v hm lng ph sa tng t 20 g/m3 ln 340 g/m3. [4]CHNG 2: PHNG PHP NGHIN CU CHT LNG MI TRNG NC VEN BIN HI PHNG2.1 Cc phng php truyn thng2.1.1 Phng php ly mu v phn tch trong phng th nghimy l phng php c s dng t rt lu tnh ton cc ch s cht lng mi trng nc. Ly mu l khu u tin v quan trng ca qu trnh phn tch. Ly mu nc phi tun th cc nguyn tc chung ca phng php ly mu v tnh in hnh, tnh ngu nhin v tnh cht cng ca mu khng b thay i trc khi n c phng th nghim. Cn ly mu sao cho mu ly c ging vi nc c s dng trn thc t. V vy m bo cho cng vic ly mu phn tch c tt, nht thit phi thc hin cng tc QA(quality assurance-m bo cht lng)/QC(quality control-kim sot cht lng)+ Bao am cht lng (QA: Quality Assurance) trong quan trc mi trng la mt h thng tich hp cac hoat ng quan ly va ky thut trong mt t chc nhm bao am cho hoat ng quan trc mi trng at c cac tiu chun cht lng a quy inh.+ Kim soat cht lng (QC: Quality Control) trong quan trc mi trng la vic thc hin cac bin phap anh gia, theo doi va kip thi iu chinh at c chinh xac va tp trung cua cac phep o theo yu cu cua cac tiu chun cht lng nhm bao am cho hoat ng quan trc mi trng at cac tiu chun cht lng nay

Hnh 2.1: Quy trnh chung v QA/QC trong ly mu v phn tchPhng php ly mu v phn tch trong phng th nghim c u im l cho kt qu phn tch c chnh xc cao, nhng phng php ny thng yu cu rt cao v nghim ngt qu trnh ly mu cng nh vn chuyn mu v phng th nghim, iu kin bo qun v cht lng ng nghim, bo qun mu, mt khc, n cn b hn ch bi phm vi ly mu v thi tit. Quy trnh ly mu phc tp, nhiu cng on v mt nhiu thi gian, nhng ch cn sai mt bc hoc khng lm ng k thut th kt qu s lch rt nhiu v khng phn nh chnh xc c hin trng.2.1.2 Phng php quan trc ti hin trngQuan trc mi trng (QTMT) la mt qua trinh o ac thng xuyn mt hoc nhiu chi tiu v tinh cht vt ly, hoa hoc va sinh hoc cua cac thanh phn mi trng, theo mt k hoach lp sn v thi gian, khng gian, phng phap va quy trinh o lng, cung cp cac thng tin c ban co tin cy, chinh xac cao va co th anh gia c din bin cht lng mi trng[20]. em li kt qu quan trc c chnh xc cao nht cn phi m bo v cht lng (QA) v kim sot cht lng (QC).

Quan ly mi trng Phn tich trong PTNNhu cu thng tinS dung thng tinChng trinh quan trcThit k mang liBao caoPhn tich s liuLy mu va quan trc tai hin trngX ly s liu

Hinh 2.2 Cac bc chu yu trong quan trc va phn tich mi trngPhng php ny cho kt qu nhanh, thng xuyn hn phng php ly mu v phn tch trong phng th nghim nhng n vn b hn ch bi cc im quan trc nn khng th quan trc trn mt din rng, ngoi ra, chi ph cho vic quan trc ny thng u t rt ln v my mc, thit b v thng hay xy ra s c k thut.2.2 Phng php Vin thm v GIS2.2.1 Tng quan v vn nghin cu ng dng vin thm v GIS trong vn mi trng nc trn th gii, Vit Nam v khu vc nghin cua. Trn th giiNghin cu cht lng cc vng nc ven b v cc vng bin rng bng cng ngh Vin thm c ng dng tng i ph bin v rng ri trn th gii. B cm CZCS (Coastal Zone Color Scanner) trn v tinh Nimbus-7 c phng vo nm 1978 c xem nh l thit b c s u tin c kh nng gim st mu nc i dng thng qua s phn b ca cht dip lc lin quan n cc hot ng ca thc vt ph du. CZCS hot ng ti nm 1986 v ng gp ng k cho vic nghin cu mi trng bin v cc qu trnh sinh hc, sinh ho v vt l ca i dng (Myller-Karger, 1989; Abbott and Chelton, 1991; Mclain, 1993; Barale and Schlittenhardt, 1993; Mitchell, 1994; Tang et al., 1998). Sau mt thp k vic gim st mi trng nc i dng b lng qun, nm 1996, b cm OCTS (Ocean Color and Temperature Scanner) ca v tinh ADEOS l th h sau ca b cm CZCS ra i v cung cp ngun d liu v lng chlorophyll, cc cht ha tan trong nc v phn b nhit b mt trn bin v i dng ton cu vi phn gii khng gian cao (Kawamura et al., 1998). T , rt nhiu nghin cu c thc hin v kim tra, xc nh gi tr v chnh xc ca d liu mu nc i dng ca b cm OCTS (Kishino et al., 1998; Shimada et al., 1998, Yokouchi et al., 2000; Tang et al., 2002).B cm SeaWiFS (Sea-viewing Wide Field-of-view Sensor) ca v tinh SeaStar bt u hot ng t ngy 18 thng 9 nm 1997 cung cp d liu c nh chlorophyll-a trn cc i dng ton cu v cc quang sinh lng khc cho cng ng cc nh nghin cu quc t t n nay. V tinh AQUA mang b cm MODIS c phng thnh cng vo ngy 04 thng 5 nm 2002. D liu MODIS-Aqua vi 36 knh ph, phn gii khng gian 250m, tn sut lp li l 2 ngy cung cp ci nhn tng th ton cu v trng nhit v Chlorophyll-a mt bin t thng 7 nm 2002 n nay. Vo ngy 16 thng 12 nm 2002, Nht Bn phng v tinh ADEOS-II (Midori-2) mang b cm GLI vi mc tiu quan st i dng ton cu. n 16 thng 1 nm 2003, GLI thu nh u tin. n 27 thng 10 nm 2003 th v tinh b trc trc k thut v khng th tip tc thu nh.Ngoi h thng v tinh cc v tinh gim st mu nc i dng chnh trn y, mt s nc khc nh n , Trung Quc, Hn Quc, i Loan cng c nhng v tinh gim st mu nc i dng ring.i vi cc vng nc ven b nh cc khu vc vng, vnh v vng ca sng, vin thm gim st mu nc vn cn nhng bt cp nh phn gii khng gian ca cc d liu vin thm cn kh nh. iu ny khng p ng c yu cu lp cc bn cht lng nc t l ln phc v cng tc qun l mi trng a phng. Thm na, cc vng nc ven b l ni tng tc gia lc a v bin dn n ch hi vn rt phc tp, mi mt vng li c ch thy-hi vn ring, iu ny gy kh khn rt ln cho vic thit lp mt thut ton x l d liu vin thm xc nh cht lng nc m c th p dng chung cho cc vng a l khc nhau. Chnh v vy, ti mi vng a l khc nhau cn phi c nhng thng s hiu chnh cho ph hp vi cc thut ton. Vic tm ra cc thng s ny i hi phi c nhng nghin cu su v chi tit. c nhiu nghin cu trn th gii v xy dng cc thut ton x l d liu vin thm quan trc cht lng nc nh: Nghin cu ca cc tc gi Howard B. Glasgrow., JoAnn M. Burkhoder., Robert E. Reed., Alan J. Lewitus., Joseph E. kleinman., 2004 v xy dng thut ton x l nh v tinh Landsat TM quan trc cht lng nc ti khu vc vnh Miami; Nghin cu ca V. Volpe., S.Silvestri., M.Marani, 2011 v Xiaoling Chen., Yok Shueng Li., Zhiang Liu., Kedong Yin., Zhilin Li., Onyx WH., Wai., Bruce King., 2004 v quan trc cht lng nc ti cc vng ca sng Italia v Hng Kng s dng d liu vin thm... u cho cc kt qu c tin cy cao. Cc nghin cu trn u s dng kt qu kho st thc a thit lp mi quan h gia ph phn x ca nh sng vi thng s cht lng nc. Trn c s mi quan h ny, d liu vin thm c x l v nh gi kt qu v rt ra c thut ton x l. Tuy nhin, cc nghin cu trn nu em p dng cho vng a l khc th chnh xc s gim i ng k.b. Trong ncT liu vin thm c ng dng rng ri trong nc phc v pht trin kinh t x hi, bo v ti nguyn v mi trng. Tuy nhin cho n nay, cc nghin cu v ng dng vin thm trong nh gi cht lng nc mi ch dng li nhng bc u.Trong nhng nm qua, c mt s ti nghin cu ng dng vin thm RADAR v mu nc quan trc cht lng nc vng bin Vit Nam do cc vin nghin cu chuyn ngnh v bin thc hin:- ti cp nh nc nhim du trn bin Vit Nam v bin ng - KC.09.22/ 06-10 do Vin a l thc hin trong giai on 2008 2010, ti a ra c bn nguy c nhim du trn bin v rt ra c mt s kt lun u tin v quy lut phn b khng gian ca nhim du trn vng bin Vit Nam v Bin ng.- ti cp Vin Hn lm Khoa hc v Cng ngh Vit Nam ng dng d liu vin thm SeaWiFS nghin cu mi trng nc vnh Bc B do Vin a cht v a vt l bin thc hin nm 2007..Hin nay, Vin Nghin cu v s Pht trin Php (IRD), Phng th nghim nghin cu a vt l v Hi dng hc- LEGOS, i hc KH v Cng ngh H Ni kt hp vi Vin Ti nguyn v mi trng bin thc hin ti Vietnam TELdetection (VITEL) ti vng bin ca sng Hng v M Kng vi cc mc tiu chnh: o c v phn tch bin ng theo khng gian v thi gian cc c trng quang hc vn c vng ca sng v ven bin; thit lp cc thut ton x l nh v tinh xc nh hm lng trm tch l lng TSS, Chl-a da trn cc kt qu kho st v vt l, sinh hc ca c, thc vt ph du, carbon hu c ha tan CDOM.... Mt s cng b v kt qu ng dng vin thm mu nc xc nh hm lng phn b ca Chl-a, TSS v trng nhit trn vng bin Vit Nam. l cc cng b ca Tran Van Dien, Dan Ling Tang , Hiroshi Kawamura, 2002; DanLing Tang, H. Kawamura, M.A. Lee, Tran Van Dien, 2003; Trn Vn in, Trn nh Ln, Thu Hng, 2005; Tran Van Dien, 2005 v Trn Vn in, Phm Ngc Hi, 2006.. Cc s liu ca ti ny c th c s dng ging nh ngun ti liu tham kho rt hu ch khi tin hnh ti nghin cu ny2.2.2 Phng php Vin thm trong nghin cu cht lng mi trng ncPhng php vin thm l phng php s dng bc x in t ( nh sng nhit), vi sng ( radar) nh mt phng tin iu tra, o c thu thp, phn tch thng tin hoc v nhng c tnh ca i tng hoc ca cc hin tng m khng phi tip xc trc tip vi i tng hoc cc hin tng Th mnh ca phng php vin thm so vi cc phng php cn li l c im a phn gii ca d liu v d liu thu c trn din rng, c nhng khu vc con ngi kh c th tip cn.+ phn gii khng gian: L kch thc ca pixel trn mt t, hay kch thc ca cc i tng nh nht c kh nng phn bit trn nh. phn gii khng gian trn nh s c quyt nh bi gc nhn tc thi ca sensor. phn gii ca nh v tinh c th siu cao n 0,6m vi nh Quickbird, phn gii trung bnh vi 10m hoc 20m vi anh Spot, 30m vi nh Landsat n phn gii thp 1km ca nh NOAA.+ phn gii thi gian: Thi gian cc b cm thu nhn tn hiu mt t. V d: Landsat 7 v Landsat 8 u c phn gii thi gian l 16 ngy, nh Spot l 26 ngy. phn gii thi gian cho php theo di v nghin cu cc bin ng.+ phn gii ph: L s lng v kch thc ca cc khong ph m b cm ghi nhn v thu li d liu. V d: knh blue, green, red, cn hng ngoi, hng ngoi nhit, vi sng ( radar ), ngoi ra cn lin quan n c ch ghi thng tin ph.+ phn gii bc x th hin mc nhy ca b cm bin vi bc x in t n, ngha l c bao nhiu s thay i bc x trn b cm bin trc khi mt s thay i gi tr sng xy ra (Jensen, J. R, 2005). phn gii bc x thp s thu nhn nh s dng s lng t cp sng, ngha l, tng phn rt cao. Trong khi , phn gii bc x cao s thu nhn bc nh s dng nhiu cp sng. V d, nh Landsat 1 MSS thu nhn nng lng bc x trong 6 bits (gi tr thay i t 0 63) v sau ny tng ln 7 bits (gi tr thay i t 0 127). Trong khi , d liu Landsat TM v ETM+ thu nhn 8 bits, ngha l cp sng thay i t 0 255. Hin nay, Landsat 8 c phn gii bc x ln ti 12 bits. ng dng Vin thm trong nghin cu mi trng ncDo cc thng tin vin thm c lin quan trc tip n nng lng phn x t cc i tng t nhin, nn vic nghin cu cc tnh cht quang hc, ch yu l c trng ph phn x ca cc i tng t nhin ng vai tr ht sc quan trng i vi vic ng dng c hiu qu phng php vin thm. Phn ln cc phng php ng dng vin thm c s dng hin nay u c lin quan trc tip hoc gin tip vi vic nghin cu c trng phn x ph ca cc i tng hay nhm i tng t nhin.Trong lnh vc vin thm, kt qu gii on cc thng tin ph thuc rt nhiu vo s hiu bit mi tng quan gia phn x ph v bn cht, trng thi ca i tng t nhin. Nhng thng tin v c trng phn x ph s cho php cc nh chuyn mn chn knh ph ti u cha nhiu thng tin v i tng nghin cu nht, ng thi cng l c s phn tch cc tnh cht ca i tng a l, tin ti phn loi cc i tng .Chnh v vy, trong nghin cu v cht lng nc, cn hiu r v phn x ph ca i tng nc

Hnh 2.3: th ng cong ph phn x ca t nc thc vt[31]Kh nng phn x ph ca nc thay i theo bc x ca sng chiu ti v thnh phn vt cht c trong nc. Kh nng phn x y cn ph thuc vo b mt nc v trng thi ca nc. Trn knh hng ngoi v cn hng ngoi ng b nc c pht hin rt d dng, cn mt s c tnh ca nc cn phi s dng di sng nhn thy nhn bit Phn ln nng lng bc x mt tri chiu ti u b nc hp th cho qu trnh tng nhit nc. Phn nng lng phn x trn b mt kt hp vi nng lng sinh ra sau qu trnh tn x vi cc ht vt cht l lng trong nc phn x li, to thnh nng lng phn x ca nc. V vy, kh nng phn x ca cc loi nc thp dn v gim theo chiu tng ca bc sng. Bc x mt tri hu nh b nc hp th hon ton vng hng ngoi v cn hng ngoi. Da vo c trung ph phn x ca tng i tng nc m phng php vin thm c th gip tnh ton nhiu thng s cht lng mi trng nc nh : c, mn, chlorophyll, vt du loang, su, ha cht nng nghip. Trong khun kh kha lun tt nghip, sinh vin la chn s dng phng php vin thm tnh ton th nghim 4 thng s cht lng mi trng nc sau: c, mn, chlorophyll, nhit . y l 4 thng s c vai quan trng nh gi cht lng mi trng nc, c bit c ngha trong vic khoanh vng v bo tn cc h sinh thi vng ven bin thnh ph Hi Phng.a. c c l mt c tnh vt l ca nc. c c th do cc cht l lng chng hn nh: trm tch, bn, t st, cht hu c, v c v cc vi sinh vt gy ra. Nguyn nhn gy ra c vng ca sng ven bin ch yu do nc sng t u ngun a trm tch ra. c c th nh hng n h sinh thi thy sinh bng cch nh hng ti qu trnh quang hp, h hp v sinh sn ca sinh vt thy sinh, ngoi ra c cn nh hng n cht lng nc dng cho mt s nghnh cng nh trong i sng sinh hot ca con ngiVin thm nghin cu c ca nc c bt u trn th gii t nhng nm 1970. Ritchie v cng s, 1974 pht trin mt phng php tip cn thc nghim tnh trm tch trong nc vi phng trnh tng qut nh sau: Y = AX+BTrong : Y: l phn x o t cm binX : l cht lng nc nh ph xa l lng, c.A, B l h s thc nghim tnh ton c t mi quan h thng k gia c v ph phn x ti mt s im o ca khu vcT cc phn x quang ph n c th cung cp cho cc thng tin v cc knh nh hay bc sng thch hp cho tham s c ca nc.[21]Cc nghin cu cho thy nc c c kh nng phn x ph cao hn trong nc, nht l nhng di sng di. Ngi ta xc nh rng vi su ti thiu l 30m, nng gy c l 10mg/l, th kh nng phn x ph lc l hm s ca thnh phn nc ch khng phi cht y. ng dng phng trnh tnh ton hi quy gia c v phn x ca nc c, c nhiu tc gi nghin cu v a ra mt s cng thc tnh ton cho khu vc nghin cu ca mnh nh:+ Nghin cu ca Han v Jordan ( 2005)[19] ti mt ca sng thuc vnh Pensacol, l 1 trong 39 ca sng ca vnh Mexico, vi t liu l nh Landsat 7 ETM da vo ch s khc bit trm tch ( NDSSI) =( Blue NIR)/(Blue+NIR) tnh ton c cho khu vc ny l : SSC = 18,69 x NDSSI-3.399+ Nghin cu c vng ca sng ca vnh Tampa, Florida, Max J. Moreno-Madrinan v cng s thc hin ly mu ti khu vc nghin cu v da vo s tng quan gia nc c v phn x a ra cng thc sau.y = 165.93 x (Red) + 1.213 Cng thc cho h s tng quan kh cao R2= 0.7567[25]Vi khu vc Hi Phng c mt s nghin cu lin quan n c, c bit trong nghin cu S dng phng php thc nghim xy dng hm hi quy tuyn tnh gia ph phn x v c ca nc bin thnh ph Hi Phng ca PGS.Ts Nguyn Hiu v Ths. Phm Xun Cnh .Nghin cu ch ra s tng quan mnh gia c v ch s c ( NDTI = (Red Green)/( Red+Green)).[2] c ca khu vc tnh theo cng thc :

Hnh 2.4: Hm tng quan gia c v ch s NDTIVi R2= 0.9732 th hin s tng quan rt mnh. V vy sinh vin la chn cng thc ny tnh ton c cho khu vc.b. mn mnhay muic k hiu S (S vit tt t chsalinity- mn) l tng lng (tnh theo gram) cccht mui ha tan cha trong 1 kgnc. Trong hi dng hc, ngi ta s dng mui (salinity) c trng cho khong ca nc bin, n c hiu nh tng lng tnh bng gam ca tt c cc cht khong rn ho tan c trong 1 kg nc bin[27]. mn l mt thng s cn thit nh gi cht lng mi trng nc,c bit mn c ngha ht sc trong trong vic tnh ton cht lng mi trng nc nhm tm kim v nh gi s pht trin ca cc loi sinh vt bin, v nui trng thy hi sn ca ngi dnVic nghin cu mn nc bin pht trin t rt lu, trong ngun d liu c cung cp t c s d liu ca nh v tinh NOAA AVHRR t nm 2000 n nm 2009, c nhiu cng trnh nghin cu mn t nh v tinh ny cho vc ven bin nh: Lee v cng s (2005) a ra hm hi quy y = 0.075x 3.0, v nghin cu thy chnh xc ca c s d liu ny l 0.6oC.Da trn vic nh gi, tnh ton th cho khu vc nghin cu, sinh vin la chn cng thc ca Han ti khu vc ca sng[19] tnh ton cho khu vc Hi Phng.

Vi: TM1, TM2, TM3, TM4, TM5 ln lt l cc knh nh ca Landsat 7 v knh 2,knh 3, knh 4, knh 5, knh 6 ca Landsat 8c. Chlorphyll ( cht dip lc )Cht dip lc ( Clorophyll) l sc t quang tng hp mu xanh l cy c thc vt, to, vi khun lam. Chlorophyll a l mt thng s gin tip nh gi mc ph dng trong nc.Theo tiu chun cht lng nc Hng Kng hin tng ph dng ca nc c th gy ra bi s vt qu nng cht dip lc c trong to khi nng chlorophyll vt qu 10g/l[23]. Hm lng chlorophyll trong nc l mt yu t nh hng ti kh nng phn x ph. N lm gim kh nng phn x ph ca nc bc sng ngn v tng phn x ph ca nc bc sng c mu xanh l cy.Trong Chlorophyll-a concentration estimated by hyperspectral remote sensing in Liadong bay , Jingjing Wang da vo vic tnh ton hi quy tng quan gia phn x ca knh c bc sng 681 m vi nng cht dip lc trong nc v a ra cng thc tnh hm lng chlorophyll cho khu vc ca sng ven bin nh sau : y= 114443X+ 22.821 ( vi X l phn x ca nc ti bc sng 681 m).[3]Mt nghin cu khc cho khu vc ca sng ca Han v Jordan ( 2005)[19] ti khu vc Vnh Pensacol, thuc mt trong 39 vng ca sng ven bin ca vnh Mexico, vi t liu s dng l nh landsat 7 ETM+, bo co cho thy c s tng quan mnh m gi h s logarit ca chlorophyll vi logarit ca t s 2 knh nh l Blue/Red, sau khi tnh ton hm hi quy, cng thc tnh chlorophyll cho khu vc ny l:

Vi: TM 1 l gi tr phn x ca knh 1 i vi landsat 7 v knh 2 i vi Landsat 8TM 3 l gi tr phn x ca knh 4 i vi landsat 7 v knh 5 i vi Landsat 8So snh mt s tnh cht ca khu vc trn vi khu vc nghin cu c mt s nt tng ng nh : u chu tc ng ca sng bin, nh hng ca mt s dng t lc a chy ra, kt hp vi vic tnh ton v so snh kt qu vi mt s ti liu tham kho c v nng chlorophyll ca khu vc nghin cu, sinh vin nhn thy cng thc trn c th s dng tnh ton cho khu vc nghin cu, mt s sai s nh c th c hiu chnhd. Nhit Nhit l thng s ng vai tr quan trng i vi h sinh thi thy sinh ven bin v n nh hng ti mc oxi ha ha tan, qu trnh quang hp v ngun cung cp thc n. Cc vng nc qu nng hoc qu lnh cc tc ng nghim trng ti nhiu loi sinh vt, thc vt bin qu him nh san h, cc loi c cc loi thy sinh khc.Chnh v mc quan trng ny ca nhit m c nhiu v tinh c ring knh nh phc v cho vic tnh ton nhit b mt nh: V tinh NOAA-AVHRR, v tinh a tnh GEOS, v tinh kh tng phng th DMSP, MODIS, LANDSAT[21]Vin thm hng ngoi nhit, gi tt l Vin thm nhit lin quan n cc sng t vi bc sng gia 3,5 - 20. Hu ht cc ng dng vin thm nhit thng s dng dy bc sng t 8 13. Nhit b mt nc c tnh t knh nhit 6 ca Landsat 7 ETM+ vi bc sng t 10.44m 12.42m, phn gii 60m, v t 10.3m 12.5m i vi Landsat 8 vi b cm bin hng ngoi nhit (TIRS Thermal Infrared Sensor) s thu thp d liu hai knh hng ngoi nhit sng di ( knh 10 v knh 11 )Da trn php tnh chuyn i gi tr t xm trn cc knh hng ngoi nhit ca nh Landsat: qu trnh thc hin bt u t vic chuyn i gi tr s ( Digital Number DN) sang gi tr bc x ph, sau chuyn i tip gi tr bc x ny sang gi tr nhit .nh knh 6 ca Landsat ETM+ v knh 10 ca Landsat 8 c th chuyn i t gi tr bc x ph sang bin vt l hu ch hn. y l nhit hiu qu trn nh v tinh (nhit vt th en) ca h thng c nhin t Tri t - kh quyn di gi thit s pht x bng 1. Cng thc chuyn i theo cng thc Plack:T= [26]Trong :+ T = Nhit hiu qu trn v tinh ( n v Kelvin )+L: Gi tr bc x ph ( W/m2.sr.m).( Cc thng s c ly t file *MTL.txt ca nh v tinh nm 2000 v 2014). Chuyn nhit Kelvin v n v Celcius (oC)+ Gi tr nhit tnh theo oC: T (oC) = T (Kelvin) 273.16+ Chuyn gi tr nhit v dng s nguyn: Fix(T) = T (oC)2.2.3 Phng php GIS trong nghin cu cht lng mi trng nc.Nu ch c kt qu gii on hin trng t cc nh vin thm th khng gii quyt c cc bi ton tch hp thng tin hay tnh ton s bin ng ca cc i tng khng gian bng cc d liu vin thm a thi gian, c bit trong trng hp d liu khng ng b nu khng c s tr gip ca cng ngh GIS.. Hnh 2.5 : S mi quan h gia GIS v Vin Thm trong nghin cu mi trngGIS c th xem xt nh mt c s d liu s c lin kt trong mt h ta a l nht nh, cho php: Nhp d liu, lu tr d liu, truy cp v hi p: chuyn i d liu, phn tch v m hnh ha: hin th (biu bng, bn , bo co,v.v.). Chnh v vy, GIS l cng c mnh trong hin th trc quan nhng g m ngi s dng mong mun. ng thi chnh chc nng phn tch ca GIS gip cho ngi s dng d dng tnh ton, m hnh ha v d on trc kt qu.Trong nh gi cht lng mi trng nc th cn kt hp nhiu ch tiu, v d nh mun nh gi cht lng mi trng nc c ph hp cho s sinh trng v pht trin ca rn san h hay khng th cn thit pho nh gi tch hp trn nhiu thng s nh: c, mn, nhit V vy GIS gip ngi dng c th nh gi mt cch ton din v tng th, to nn mt h thng c s d liu nn hon thin. D liu GIS cung cp v tch hp a dng v ni dung, bao gm c d liu khng gian v d liu thuc tnh. Cc d liu lu trong GIS theo hai dng raster v vector lun c cp nht v sn sng tra cu thng tin hay thc hin cc bi ton phn tch, th hin dng bn trc quan.

CHNG 3: NG DNG VIN THM V GIS NGHIN CU V NH GI S THAY I CHT LNG MI TRNG NC KHU VC VEN BIN HI PHNG3.1. T liu s dng3.1.1 nh landsat Landsat l mt h thng v tinh khng ngi iu khin ca M, thu nh theo phng php qut c phng ln qu o t nm 1974. n nay c 8 v tinh Landsat c phng ln, nhng ch cn Landsat 7 v Landsat 8 hot ng, tuy nhin, Landsat 7 t nm 2003 b li gch sc trn nh [5]. V tinh Landsat cung cp nh c phn gii trung bnh, khong thi gian v tinh lp li 1 khu vc l 16 ngy ( i vi Landsat 7 v Landsat 8), vic ny gip theo di kp thi nhng bin ng mi trng c th xy ra, ngoi ra nh Landsat cn c cung cp cho ngi s dng. Chnh v vy, vic la chn nh Landsat cho nghin cu cht lng mi trng nc ven bin l hon ton hp l, c th trong kha lun sinh vin s dng Landsat 7 v Landsat 8. Landsat 7 nh Landsat 7 s dng trong nghin cu ny c thu ngy 15 thng 8 nm 2000 vi kt qu khi gii nn d liu c cc knh nh nh sau:

Hnh 3.1: Kt qu gii nn tp nh Landsat 7Landsat 7 l v tinh Landsat th h th 7 ca M, c b cm ETM+ nng cp t b cm TM. B cm bn chuyn TM l b qut a ph nng cao. B cm nghin cu ti nguyn tri t c thit k thu nhn nh c phn gii cao hn, tch cc ph c nt cao hn, ci thin c chnh xc hnh hc v chnh xc bc x kh quyn tt hn b cm MSS. B cm ny c rng di qut l 185 km, mi pixel mt t c kch c l 30 m x30 m, tr knh hng ngoi nhit (knh 7 c phn gii 120 mx120 m). B cm TM c 7 knh ghi ng thi s phn x hoc bc x pht ra t b mt tri t di dng mu lam-lc (knh 1), lc (knh 2), (knh 3), cn hng ngoi (knh 4), hng ngoi gia (knh 5 v 7), hng ngoi xa (knh 6) theo di ph sng in t. Knh 2 ca b cm TM pht hin phn x lc t thc vt sinh trng tt v knh 3 c thit k pht hin s hp th cht dip lc ca thc vt. Knh 4 TM dng nhn bit phn x cn hng ngoi i vi thc vt mu lc sinh trng tt, ranh gii gia t v nc. Knh 1 TM c th xuyn qua nc lp cc bn su dc theo vng ven b v c dng ph bin phn loi t v thc ph cng nh phn loi rng. Hai knh hng ngoi gia TM c dng nghin cu thc vt v t m, xt on gia v khong sn. Knh hng ngoi xa TM c thit k tr gip thnh lp bn nhit v nghin cu vng t m v thc vt.LANDSAT-7 c trang b thm vi b bn chuyn nng cp ETM+ c k tha t b TM. Cc knh quan trc ch yu tng t nh nh b TM, v knh mi c thm vo l knh en trng (knh 8) c phn gii l 15 m. Tuy nhin, ngy 31/5/2003 thit b gp s c k thut. Kt qu l tt c cc cnh Landsat 7 c thu nhn k t ngy 14/7/2003 n nay u ch "SLC-off" ngha l xut hin cc vt sc en cch u.Hin nay, nh v tinh Landsat hon ton c th khai thc min ph t trn mng Internet qua a chhttp://glovis.usgs.gov/. Landsat 8nh Landsat 8 s dng trong nghin cu ny c thu ngy 23 thng 7 nm 2014 vi kt qu gii nn c cc knh nh sau:

Hnh 3.2: Kt qu gii nn tp nh Landsat 8V tinh th h th 8 Landsat 8 c M phng thnh cng ln qu o ngy 11/02/2013 vi tn gi gc l Landsat Data Continuity Mission (LCDM). Landsat cng cp cc nh c phn gii trung bnh t 15 100m, ph kn vng cc cng nh. Nhim v ca Landsat 8 l cung cp nhng thng tin quan trng trong nhiu lnh vc nh qun l nng lng v nc, theo di rng, gim st ti nguyn mi trng [26]. Thng tin chi tit v v tinh Landsat 8 do c quan o c a cht M cung cp USGS. )Landsat 8 (LCDM) mang theo 2 b cm: b thu nhn nh mt t ( OLI Operational Land Imager) v b cm bin hng ngoi nhit (TIRS Thermal Infrared Sensor). Nhng b cm ny thit k ci thin hiu sut v tin cy cao hn so vi cc b cm Landsat th h trc. Landsat 8 thu nhn nh vi tng s 11 knh ph, bao gm 9 knh sng nhn v 2 knh nhit sng di. Hai b cm ny s cung cp chi tit b mt Tri t theo ma phn gii 30m ( cc knh nhn thy, cn hng ngoi v hng ngoi ngn); 100m knh nhit v 15m i vi knh ton sc. Di. cao v tinh t 705km so vi b mt Tri t.Bng 3.1 : c trng b cm ca nh v tinh Landsat 7 v Landsat 8 (LCDM) [26]V tinhBandsWavelength(micrometers)Resolution(meters)

Landsat7(B cm ETM+)Band 10.45-0.5230

Band 20.52-0.6030

Band 30.63-0.6930

Band 40.77-0.9030

Band 51.55-1.7530

Band 610.40-12.5060 (30)

Band 72.09-2.3530

Band 8.52-.9015

LDCM Landsat 8(B cm OLI v TIRs)Band 1 - Coastal aerosol0.433 - 0.45330

Band 2 Blue0.450 - 0.51530

Band 3 Green0.525 - 0.60030

Band 4 Red0.630 - 0.68030

Band 5 - Near Infrared (NIR)0.845 - 0.88530

Band 6 - SWIR 11.560 - 1.66030

Band 7 - SWIR 22.100 - 2.30030

Band 8 Panchromatic0.500 - 0.68015

Band 9 Cirrus1.360 - 1.39030

Band 10 - Thermal Infrared (TIR) 110.3 - 11.3100

Band 11 - Thermal Infrared (TIR) 211.5 - 12.5100

B cm OLI cung cp 2 knh ph mi, knh 1 dng quan trc bin ng nc vng ven b v knh 9 dng pht hin cc mt dy, mng ca m my ti ( c ngha i vi kh tng hc), trong khi b cm TIRS s thu thp s liu t hai knh hng ngoi nhit sng di ( knh 10 v 11 ) dng o tc bc hi nc, nhit b mt. B cm OLI v TIRS c thit k ci tin gim thiu ti a nhim kh quyn, cho php lng t ha d liu l 12 bt nn cht lng hnh nh tng ln so vi phin bn trc[26]

Hnh 3.3: th c trng ph ca nh v tinh Landsat v Landsat 8 [26]- nh t hp nh mu gi tiu chun cho khu vc nghin cu nm 2000 v nm 2014 a bHnh 3.4 nh t hp mu gi khu vc nghin cu vi a l nm 2000, b l nm 20143.1.2 D liu o thng s cht lng mi trng ncVi mc ch so snh, i chiu v nh gi v kt qu tnh ton ca nghin cu, ngoi ra cn phc v cho vic nghin cu lin quan n bin ng cc thng s sinh vin s dng mt s ti liu l cc thng s cht lng nc o ti mt s im ca khu v nghin cu. + Kt qu o c thng s nc Hi Phng nm 2005Bng 3.1: Kt qu o cht cc thng s nc ti Hi Phng nm 2005

+ Kt qu o c v phn x ti khu vc Hi Phng nm 2014[2]Bng 3.2: Kt qu o v ch s c (NDTI ) nm 2014 ti Hi Phng

3.2. Quy trnh nghin cu v nh gi s thay i cht lng mi trng ncQu trnh tnh ton, x l nh vin thm v cc ti liu tham kho a ra cc bn thng s cht lng mi trng c tin hnh da trn quy trnh sau.

Hnh 3.5. : Quy trnh nghin cu v nh gi cht lng mi trng nc ven bin Hi Phng3.3 Kt qu x l nh 3.3.1 Chun haTrong qu trnh x l pht hin s thay i, chng ta phi xem xt cc im nh c th b thay i bi cc yu t nh m, iu kin kh quyn, gc mt tri v cc thng s cm bin.Mc ch ca phng php ny l loi b nhng nh hng trn m bo rng cc thay i ch c th xy ra khi tnh nng b mt thay iCng vic chun ha c thc hin trn phn mm ENVI vi cng c Radiometric Calibration, Dark Subtraction v Histogram Matching.3.3.2 Nn chnh nhVi nh Landsat c ng k vi h ta chun l WGS 84, nhng t liu s dng tham kho nh bn a hnh li s dng h ta chun quc gia VN-2000, nn thun tin cho qu trnh tnh ton, tham kho, so snh v i chiu th cn thit phi chuyn i h ta ca 2 nh Landsat v h ta chun quc gia. y l qu trnh nn chnh hnh hc rt cn thit.Qu trnh nn chnh hnh hc c tin hnh nhm gim ti a sai s v tr, bin dng hnh hc trn nh v a nh v h ta quy nh (theo h ta VN 2000).Ngoi ra, i vi nh nhit ( nh knh 6 i vi Landsat 7 v knh 10, knh 11 ca Landsat 8) rt hay b mo do nh hng ca cc yu t mi trng nh: gi, ma, my, thc vt nn vic nn chnh nh l cn thit cho kt qu c chnh xc cao nhtVic x l ph v nn chnh hnh hc nh v tinh Landsat 7 d dng thc hin bng cc phn mm chuyn dng nh Envi, Erdas. Ci chnh sai s h thng (mc 1G) v x l vt k sc (SLC-off) bao gm ci chnh nhiu bc x, ci chnh hnh hc v b sung nhng pixel b thiu ch SLC-off. Vic tnh ton cc pixel thiu da vo so khp xm t mt hay nhiu cc cnh b c chp cc thi im khc nhau.i vi nh Landsat u c x l mc trc nh ngha l ci chnh bin dng bi chnh cao a hnh v c ng k trong h ta WGS-84. Khi s dng chnh l, hin chnh bn a hnh s khng cn phi nn nh m ch cn tnh chuyn i v h ta VN-2000Cng vic c thc hin trn cng c Convert Map Projection trn phn mm ENVI

Hnh: 3.6 Ca s chuyn i h ta trn phn mm ENVI3.3.4. Tch vng nc ven bin khu vc nghin cu t nhDo ch nghin cu khu vc nc ven bin ch khng phi ton b khu vc nn sinh vin tin hnh ct nh theo khu vc nghin cu c phn t lin v phn bin ( ti su 30 mt ), sau tnh ton phn chi ranh gii tch nc v t tm ra khu vc nghin cu Phng php chit sut ranh gii nc t nc trn c s thng k gi tr phn x ca cc i tng trn knh t l (Band 6 /Band 3 ) i vi Landsat 8 v t l ( Band 5/Band 2) i vi Landsat 7. Knh 6 ca Landsat 8 v knh 5 ca Landsat 7 l knh hng ngoi ngn s th hin mnh m s tng quan gia t nc, do nc hp th hu nh hon ton knh ny, o d dng phn chia c ranh gii gia t v nc [26]. Kt hp vi ranh gii thnh ph Hi Phng, ta c ranh gii khu vc ven bin thnh ph Hi PhngHnh 3.8 Ranh gii Hi PhngHnh 3.7: nh t s Band 6/Band 3

Sau khi phn tch khong gi tr ca t s, nhn thy gi tr Band6/Band 3 < 0.79 l gi tr thch hp phn chia ranh gii gia t v nc. Kt hp vi ranh gii khu vc Hi Phng d dng xc nh c khu vc nc ven bin thnh ph Hi Phng.Hnh 3.9: Khu vc nghin cu ven bin Hi Phng Phng

3.3.3. Chuyn i gi tr DN ca nh sang gi tr phn x v bc xD liu Landsat ETM+ v Landsat 8 c thu nhn di dng nh s-DN. Trong qu trnh tnh ton, cn phi s dng cc gi tr ca nh di dng radian v phn x. Do cn phi chuyn i gi tr ca d liu nh s ny sang gi tr bc x ph l gi tr phn nh nng lng pht ra t mi vt th thu nhn trn knh nhit. Vic chuyn i ny c c thc hin khc nhau i vi nh Landsat 7 v Landsat 8.- i vi nh Landsat 7: chuyn i gi tr DN v gi tr Reflectance th nht thit phi thng qua bc chuyn t gi tr DN sang gi tr Radian, sau chuyn t gi tr Radian sang gi tr Reflectance+ Chuyn gi tr DN sang gi tr Radiance.[31]Radiance = L = ML * Qcal + AL

chuyn gi tr DN v gi tr Radiance s dng cng thc: + Chuyn gi tr DN sang gi tr Reflectance [31]S dng cng thc sau:R =

i vi nh Landsat 8S chuyn i t gi tr DN sang gi tr Radiance v Reflectance hon ton c lp nhau theo cc cng thc sau:+ Chuyn t gi tr DN sang gi tr Radiance [30]L=MLQcal+AL

+ Chuyn t gi tr DN sang gi tr Reflectance[3]=(MQcal+A)/ sin(SE)

Trong : n v ca L l W/(m2.sr.m). ML: yu t chuyn i radian t cc siu d liuca knh nh QCAL : gi tr bc x c hiu chnh v tnh nh lng dng nguyn.AL : l gi tr hiu chnh bc x M : Yu t chuyn i phn x t cc d liu ca nhA: L gi tr hiu chnh phn x = 3.14d : khong cch gia mt tri v tri tE (sun,) : Lng bc x mt tri : L gc cao mt triCc gi tr ca cc thng s trn hon ton khai thc c t d liu nh c n dng *MTLKt qu gi tr nh khi chuyn v gi tr phn x Hnh 3.11: nh Landsat vi gi tr phn x

Hnh 3.10 nh Landsat vi gi tr DN

3.4 Bn thng s cht lng mi trng nc3.4.1 Bn ch s cKt qu tnh ton c ca 2 nm c th hin trn bn sau.

Hnh 3.12 Bn phn vng c ven bin thh ph Hi Phng thng 8-2000

Hnh 3.13: Bn phn vng c thng 7 2014 khu vc ven bin Hi PhngNhn vo bn phn vng c ca 2 nm c th thy, vo ma ma, c ca khu vc ven bin rt ln, do chu nh hng t ngun nc do cc ca sng chy ra. Theo kt qu tnh ton ti cc ca sng, c c ni ln ti gn 1000mg/l nh ca sng Bch ng, ca Vn c, Thi Bnh, c y vt gii hn cho php rt nhiu ln. Nguyn nhn l do, gn ca sng Bch ng c khu cng nghip v cng bin nh V pht trin mnh, kt hp vi c t sng a ra nn y c c cao nht, ln ti 996 mg/l. c ln ch yu phn b cc ca sng, gn ca sng v theo dng chy sng, do lc dng chy cn ln v thng th so vi dng bin, dng chy sng v cc m nui thy hi sn. Nguyn nhn l do trong nhng nm gn y, hot ng thng ngun cc con sng din ra mnh, cng vi o l vic pht trin mnh m cc nghnh cng nghip, khu vc ven bin c a vo khai thc nhiu hn. i vi nhng khu vc m nui, c ln do tch t lng thc n d tha qua nhiu nm m cha c bin php ci to, lm cho cht lng nc ca m nui vt quy chun gp nhiu ln, iu ny s nh hng rt ln n sn lng nui trng thy hi sn .Cng ra xa b th c cng gim v phn b u hn do tc dng ca dng chy sng gim i. Khu vc c c thp ch yu xung quanh khu vc Ct B, v khu vc qun o Long Chu, chnh v vy, y l 2 khu vc san h pht trin mnh. Ti mt s khu vc ngoi bin xa, c c phn b kh phc tp, khng tun theo quy lun chung l gim t b ra khi, nguyn nhn l do s vn chuyn trm tch vng ven bin kh phc tp, ngoi ngun do sng a ra cn chu nh hng ca ch triu, ch dng chy ca sng v cc ch thy ng lc khc [33]3.4.2 Bn thng s mnKt qu tnh ton mn t nh nm 2000 v nm 2014 cho thy:+ Ti khu vc ca sng, do c s trn ln ca nc sng v nc bin nn mn ti nhng khu vc ny khng cao, ch trong khong t 9.8 n 14.5 ppt+ Ti nhng m nui thy hi sn, nc mn c bm vo nhng ko chu nh hng ca dng chy nn mn tng i cao, cao hn hn so vi khu vc nc ca sng+ Pha ng o Ct B c mn kh cao,dao ng trong khong t 20 n 30 , y l khu vc c mn thun li cho s pht trin ca san h.Nhn thy, i vi vng bin xa b mn khng phn b theo quy lun tng dn t ngoi ca sng ra xa bin do ngoi chu tc ng ca yu t sng, mn cn ph thuc vo dng hi lu thnh hnh theo ma- thng, hng gi, nhit ca ngy thu nhn nh.

Hnh 3.14: Bn phn vng mn thng 8 nm 2000 khu vc ven bin Hi Phng Kt qu tnh ton mn khu vc vo thng 7 nm 2014

Hnh 3.15: Bn phn vng mn thng 7 nm 2014 ven bin Hi Phng3.4.3 Bn ch s chlorophyll Kt qu tnh ton thng s Chlorophyll cho khu vc vo thng 8 nm 2000

Thc hin: Sv H Th Bch Phng Hng dn: PGS.TS Nguyn Ngc Thch Ths Phm Xun CnhHnh 3.16: Bn phn vng chlorophyll a ven bin Hi Phng thng 8 nm 2000Nhn vo bn c th thy, nhng khu vc c hm lng Chlorophyll cao l khu vc ca sng Vn c v ca sng Thi Bnh , y l hai ca sng c hm lng ph sa v dng chy ln c em li t thng ngun ca cc con sng ny, hm lng ph sa gim dn t ca sng ra ngoi bin v ch yu cao hn nhng khu vc chu tc ng ca dng chy sng. Khi ra xa, tc ng ca dng chy sng gim hoc b trit tiu, thay vo l tc ng ca sng v dng bin nn lng ph sa phn b u trn mt din rng. Hm lng Chlorophyll cng tng i ln nhng khu vc l m nui thy hi sn, ra rng ngp mn v ven o Ct B, do lng chlorophyll y c b xung do thc vt ti nhng khu vc y trc tip ri, rng xung bin. Tuy nhin, hm lng chlorophyll t ngng cao t 5-7mg/m3 chim din tch nh, ch yu nm trong khong t 2-4 mg/m3. Kt qu tnh ton lng Chlorophyll vo thng 7 nm 2014.

Thc hin: Sv H Th Bch Phng Hng dn: PGS.TS Nguyn Ngc Thch Ths Phm Xun CnhHnh 3.17: Bn phn vng chlorophyll a ven bin Hi Phng thng 7 nm 2014Kt qu tnh tan hm lng Chlorophyll ca khu vc cho thy, khu vc c hm lng chlorophyll cao nht l ca sng Bch ng v ca sng Thi Bnh ln ti 7 mg/m3 do hm lng chlorophyll c mang ra t cc dng sng ny rt ln nht l vo ma ma. Kt hp vi hng gi thnh hnh vo ma ny l ty nam nn dng chy ph xa c hng chy xung theo hng ty nam.Nhn chung, hm lng chlorophyll c xu hng gim dn khi xa b, nhng ti mt s khu vc gn b khng chu nh hng nhiu ca dng chy sng m chu nh hng ca dng sng th hm lng chlorophyll ch mc trung bnh nh khu vc ven b gia ca sng Cm v ca sng Bch ng. Hm lng chlorophyll nh nht l khu vc pha ng ca o Ct B, nguyn nhn l do y s lng san h gim i rt nhiu

3.4.4 Bn nhit Kt qu tnh ton nhit cho khu vc vo thng 8 nm 2000 v thng 7 nm 2014 c th hin di hai bn sau

Hnh 3.18: Bn phn vng nhit thng 8 nm 2000 khu vc ven bin Hi PhngNm 2014

Hnh 3.19: Bn phn vng nhit thng 8 nm 2000 khu vc ven bin Hi PhngNhn vo bn phn vng nhit ca 2 nm, nhn thy: khu vc c nhit nc bin cao c khi ln ti 26- 27 l cc khu vc xung quanh ca Bch ng, ca Cm , nguyn nhn l do khu vc ny l ni din ra nhiu hot ng hng hi, trong qu trnh di chuyn ca tu, bc d hng ha mt lng ln du m s tri ra bin, du m c kh nng lm tng bc x dn n khu vc c nhit nc ven b cao hn rt nhiu so vi khu vc khc.Ti cc khu vc ca sng khc nh ca sng Vn c, ca sng Thi Bnh c c cao vi lc dng chy ln em ra ca sng dng di y c nhit thp nn nhit nc mt ti nhng vng ca sng c c ln li thp.

3.5 nh gi bin ng3.5.1 nh gi bin ng c.Vi mc ch cho thy s bin ng v din phn b ca c trong nc, vic xy dng bn din tch cc vng c nm 2000 v 2014 l ht sc cn thit.

Hnh 3.20: Biu din tch gi tr cc vng c nm 2000 v 2014Da vo th c th thy, nm 2000, din tch vng c c di 100 NTU l ln nht, nhng vo nm 2014, din tch ca vng ny gim i ng k, ch bng khong 1 phn 4 ca so vi nm 2000. Trong khi nhng vng c c cao trn 200 NTU ca nm 2014 tng ln ng k so vi nm 2000, tng mnh nht l nhng vng c c trong khong 100 200 NTU v nhng vng c c ln hn 400 NTU, vng c din tch tng t v khng ng k nm trong khong t 200 300 NTU, ch trong vng 14 nm din tch c c ln hn 100 NTU tng ln 3792265 ha, tng gp 1,15 ln. Nguyn nhn l do, vng thng ngun v bn cnh cc dng sng, hot ng kinh t ang ngy cng din ra si ng hn, dn n vic nh hng n cc cht thi, trm tch ca dng sng ra bin. Nguyn nhn khc l do, hin nay vng ca sng ven bin ca Hi Phng ang c a vo khai thc s dng ngy cng nhiu hn, cng l nguyn nhn gy ra vic tng ln ng k ca c ti khu vc ny.3.5.2 nh gi bin ng Chlorophyll thy r hn s thay i hm lng chloropyll ca khu vc nm 2000 vi nm 2014 cn xy dng lt ct ti khu vc ca sng Cm, ni c hm lng chlorophyll c s bin ng r rt nht.

Hnh 3.21: V tr lt ct chlorophyll nm 2000 Hnh 3.22: V tr lt ct chlorophyll nm 2014

Hnh 3.23 S lt ct Chlorophyll nm 2000 Hnh 3.24 S lt ct Chlorophyll nm 2014

th th hin gi tr chlorophyll ti lt ct nm 2000 cho thy, hm lng cao nht xut hin ti ngay vng ca con sng vi gi tr vo khong 4 mg/m3 v phn b trn mt din hp. Nhn chung, hm lng chlorophyll c xu hng gim dn ra ngoi bin. Nhng n nm 2014, hm lng chlorophyll cao nht ko ch nm ngay ca sng m c din phn b rt rng, gi tr cao c khi ln ti 5,5 mg/m3, t ca sng ra ngoi bin, hm lng chlorophyll gim t ngt, iu ny cho thy hm lng chlorophyll nm 2014 c s tng ln ng k so vi nm 2000 c v din phn b v hm lng ti khu vc ca sng v ven bin. i vi nhng vng bin ngoi xa,do nh hng ca dng chy sng khng cn ln, thay vo l nh hng t cc dng bin, hng gi i vi mi ma, mi thng l khc nhau nn kh xc nh c quy lun chung cng nh kh xc nh c s bin i .3.5.3 nh gi bin ng mnLt ct ti khu vc ca sng Cm s cho ci nhn trc quan v s bin i mn ca khu nm 2000 v nm 2014

Hnh 3.25: V tr lt ct mn nm 2000 Hnh 3.26: V tr lt ct mn nm 2014

Hnh 3.27 S lt ct mn nm 2014 Hnh 3.28 S lt ct c nm 2014Quy lut phn b mn tng i phc tp, nhng nhn chung khu vc ca sng c mn thp do nh hng ca dng chy sng. vng ca sng, nm 2014 c mn ln hn so vi nm 2000, nguyn nhn l do, nm 2014 c lng ph sa em ra t sng ln hn, km theo vi ph xa l cc mui khong ha tan lm cho mn tng ng k t 1-2 ppt.+ Cc m nui thy hi sn nm 2014 c mn cao hn nm 2000 do s tch t thc n d tha trong qu trnh nui thy hi sn+ mn ti khu vc quanh o ct b v Long chu tng i n nh mn cc m nui thy hi sn ca nm 2014 cng c xu th tng hn so vi nm 2000 do hm lng cc mui ha tan c thm vo t hm lng thc n d tha. nhng khu vc bin xa b, mn tng i cao v bin i phc tp do nh hng ca nhiu yu t khc nhau.

3.5.4 nh gi s thay i nhit Nhit l mt c trng vt l ca nc bin, ph thuc vo nhiu yu t khc nhau. Do vng ven bin Hi Phng nm trong vng hot ng ca gi ma, vo thng 7 v thng 8 vi nh hng ca h thng gi ma ty nam thng tr vi tnh cht nng m khng ch nh hng trc tip ti nhit b mt nc thng qua nhit khng kh c trng m cn to ra cc hon lu di chuyn cc khi nc c nhng tnh cht nhit mui c trng. Xu th phn b chung ca nhit nc mt ca vng bin mang tnh cht ma va mang tnh cht a i v khng n nh theo nm, theo ma v theo tng khu vc, c bit l vo cc thng gi ma ty nam. i vi vic ng dng vin thm vo nghin cu cht lng nc th kt qu tnh ton c tnh tng i v ph thuc vo iu kin thi tit theo ngy, theo thng s nh hng ti vic bc x ca nc v thu nhn bc x nhit ca v tinh. Chinh v vy, kh c th nh gi s bin i nhit trong 2 nm khc nhau.Nghin cu yu t nhit nh l mt yu t trong cht lng mi trng nc, v n c ngha c bit quan trng trong vic nghin cu mi trng sng, tm s phn b cho mt s loi c phc v cho nh bt, v s phn b cho san h cng vi nhiu loi thy sinh khc.

KT LUN1. Vi nhng u im ca phng php vin thm v phng php GIS kt hp vi kt qu c tnh ton trong khoa lun, nhn thy vic ng dng hai phng php ny vo nghin cu, tnh ton bin ng cc thng s cht lng mi trng nc cho kt qu tt, ph hp vi quy lut pht trin kinh t ca Hi Phng giai on 2000 2014 v quy lut t nhin2. Kha lun tnh ton v thnh lp c bn cc thng s cht lng nc nh : c, mn, chlorophyll, nhit , trong phn tch c s bin ng ca cc thng s ny t nm 2000 n nm 2014.Trong giai on 2000 2014 cc yu t u c s bin i t vng ca sng ra xa: + c vng ca sng nm 2014 tng ln ng k, so vi nm 2000 c ca nm 2014 tng gp 1,15 ln. Nguyn nhn ca s gia tng c ny l do s pht trin kinh t nhanh v mnh vng ca sng ven bin, cng vi l s tng v cng hot ng kinh t thng ngun cc con sng+ mn c xu hng tng t ca sng ra bin. Khu vc ca sng, mn khng vt qu 15 ppt , khu vc ngoi bin xa b c mn phn b kh phc tp, ni cao nht c th ln ti 35 ppt, trong khi ni thp nht c th xung di 15ppt. So vi nm 2000 th ti mt s ca sng vo nm 2014 cao hn do nh hng bi lng trm tch t sng ra.+ Khc vi s phn vng ca mn, nng chlorophyll c xu hng gim dn t ca sng ra bin, nm 2014 c din phn b nng chlorophyll cao rng hn nm 2000+ Nhit ca nm 2000 v 2014 do thu vo hai ngy khc nhau, khc nhau v iu kin thi tit, yu t dng chy nh hng n lng bc m v tinh thu nhn c t bc x mt nc. Mt khc, nhit ti thi im o l nhit tc thi, nn kh c th so snh s bin i v nhit ti khu vc.

KIN NGH1. Trong khun kh ca ti cha th tnh ton c ht cc thng s cht lng mi trng nc v phng php vin thm v phng php GIS c th lm c.2. Do qu trnh thc a, o c trc tip kim chng mt rt nhiu thi gian, cn cng ngh tu thuyn v my mc hin i nn sinh vin cha c c hi c n o c trc tip nh gi kt qu, m kt qu c kim chng thng qua s so snh, i chiu t cc kt qu o c, bo co c lin quan n khu vc.3. i vi khu vc ven bin Hi Phng, qua kt qu tnh ton c th thy, hm lng c rt cao, vt tiu chun cho php gp nhiu ln, c nhng khu vc gp hn 10 ln tiu chun, chnh v vy m cc c quan chc nng cn c gii php thch hp nhm gim thiu c cho khu vc, cng nh quan tm st sao n cc thng s cht lng khc nhm pht hin kp thi v c bin php x l thch hp

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