Động học muối dinh dưỡng vực nước ven bờ vịnh Cam Ranh - Bình Ba (Khánh Hòa) - Nguyễn Hữu Huân

422 Tuyen tip HQi nghi KHOA HQC TOAN QUOC V£ SINH HQC BifeN VA PHAT T R | £ N BfeN WJntR<br /> <br /> <br /> <br /> <br /> DQNG HQC MUOI DINH D I / O N G V ^ C N I T O C VEN B 6 VINH<br /> I<br /> CAM RANH - BINH BA (KHANH HOA)<br /> <br /> Nguyen Hiiru Huan I<br /> Vien Hai duang hpc, Vi^n Khoa hpc vd Cong ngh^ Vi^t Nam<br /> <br /> <br /> I. M d DAU<br /> Hpi ty nhilu ylu to thuan Igi (la vjnh tuong d6i kin, nude sau, dieu kipn moi trudng tuong<br /> d6i 6n djnh,...), vjnh Cam Ranh - Binh Ba dang dugc sii dyng cho nhilu boat dgng kinh te - xS<br /> hpi ma chu ylu nhit la khai thac, nu6i fr6ng hai san va cang bien. Them vao dd, do bd phia tay<br /> vjnh trai dai vdi mat dp dan cu d6ng diic frong khi cira vjnh kha hpp nen lugng chat thai tir cac<br /> boat dpng noi fren ciing nhu tir ngudn nude thai sinh boat ciia cu dan noi chung, ngu6n dinh<br /> dudng noi rieng dua vao vyc nude dang va se ngay cang gia tang va dieu nay se cd anh hudng<br /> nhit djnh din m6i trudng sinh thai, den tiem nang nang suat thuy vyc. Do vay, quan trac va<br /> nghien curu dpng hpc ngudn dinh dudng vyc nude Cam Ranh - Binh Ba la rat can thiet, nham<br /> cung cip CO sd khoa hoc de xay dyng giai phap khai thac, quan ly, su dyng vyc nude ben vinig.<br /> Tren ca sd ngu6n dir lipu thu thap dugc frong khu6n kh6 dy an hgp tac Viet Nam - Dan<br /> Mach: Hamrful Algae Bloom in Vietnam (HAB - VIET), bao cao nay the hipn dac trung dpng<br /> hpc mu6i dinh dudng vyc nude ven bd vjnh Cam Ranh - Binh Ba ciing nhu mgt so yeu to chi<br /> ph6i qua trinh.<br /> <br /> n. pinroNG PHAP NGHIEN cuti<br /> <br /> L Thdi gian va dja diem nghien curu<br /> Virng nghien cuu thupc vyc nude ven bd vjnh Cam Ranh - Binh Ba, vdi hp thdngframthu<br /> mau dugc the hipn fren hinh 1.<br /> <br /> Bang 1. Dfic tru'ng cac tram thu m l u<br /> TT Tram Vidp Kinh dp Op sau (m) Ghi chu<br /> 1 1 11°52'200 109°09'000 11.0 vjnh Cam Ranh<br /> 2 2 11°54'000 109° 11'400 14.0 vjnh Cam Ranh<br /> 3 3 11°52'500 109°12'000 25.0 vjnh Binh Ba<br /> 4 4 11°48'000 109°14'100 33.0 vjnh Binh Ba<br /> <br /> Thdi gian khao sat g6m 2 dgt:<br /> - Dgt 1: Tir 01/06 - 30/6/2006, la thdi ky thupc miia kh6 cua tinh Khanh Hoa (khao sat<br /> mat rpng vao cac ngay: 1, 2, 3, 5, 10, 15, 20 va 30/6/2006).<br /> - Dgt 2: Tir 20/10 - 18/11/2006, la thdi ky thupc miia mua cua tinh Khanh Hoa (khao sat<br /> mat rpng vao cac ngay: 20, 21, 22, 24/10; 08 va 18/11; khao sat fram lien tyc ngay dem vao ngay<br /> 18/11/2006 tai fram 3).<br /> Tieu ban: CONG NGHE SINH HOC BI^N VA MOI TRLTONG 423<br /> <br /> <br /> 109.15 109.20 109.25 M<br /> <br /> <br /> <br /> <br /> 109.15 109.20 109.25<br /> iHinh 1. Ban do trfim thu mdu<br /> <br /> <br /> <br /> 2. Phuong phap thu, phan tich mau v^ xir ly so lifu<br /> Miu nude phan tich mu6i dinh dudng dugc thu tir binh thu mau plastic (dung tich 5 lit). Tai<br /> mdi fram, cac tang nude thu mau phy thupc vao dac trung phan bo thing dung ciia chl-a ghi<br /> nhan dugc tir dir lieu CTD ngay trudc khi thu mau. Mau nude sau khi thu dugc xir ly va phan<br /> tich theo dung quy trinh chuan d6i vdi mau dinh dudng trong nude biln /3, II:<br /> - Nifrit: Phuang phap Bendschneider and Robinson.<br /> - Nifrat: Phuang phap Morric and Riley.<br /> - Am6n (bao gom ca am6n va am6niac): Phuang phap Riley.<br /> - Ph6tphat: Phuang phap Murphy and Riley.<br /> - Silicat: Phuang phap Mullin and Riley.<br /> Toan bg so lieu dugc xir ly tren phan mem Excel for Windows.<br /> 424 Tuy^n tap H$i nghj KHOA HQC TOAN QUOC V£ SINH HQC BI^N VA PHAT TRifeN B^N V&Ng<br /> <br /> <br /> <br /> m . K E T Q U A NGHIEN CUtJ VA T H A O LUAN<br /> <br /> 1. Trang thai dinh dudng<br /> Nhin chung, nong dg muoi dinh dudng d vyc nude Cam Ranh - Binh Ba bien thien m ^ h<br /> theo thdi gian va kh6ng gian (bang 2, 3, hinh 2a, 2b, 3, 4a, 4b, 5a va 5b).<br /> Kit qua th6ng ke cho thiy, n6ng dp mu6i dinh dudng dao dgng trong pham vi cho phep /I/.<br /> Tuy nhien, ty so [N]/[P] biln thien frong pham vi rat rong va gia frj trung binh ciia nd thip hon<br /> nhieu so vdi ty Ip Redfield ([N]/[P] ~ 16/1) 12, 61. Dilu nay chiing td vyc nude dang d trong tinh<br /> fr^ng thilu hyt nita. Ty Ip [Si]/[P] cung dao dpng trong pham vi rong va gia frj trung binh Idn<br /> hon nhilu so vdi ty le Redfield ([Si]/[P] = 15/1) /2/. Dae diem nay phii hgp cho sy phat trien cua<br /> tao silic - mgt frong 2 nhdm tao uu thi nhat frong mdi trudng bien.<br /> Khac vdi tit ca cac muoi dinh dudng con lai, nifrit co nong dg rat thap va vi the cung kh6ng<br /> cd sy biln thien dang kl vl thdi gian va ca khdng gian. Nhieu nghien ciiu fren the gidi cho thay,<br /> trong nude biln, nifrit thuong cd ndng dg rat thip (trung binh khoang l,5pg/l) nhung trong<br /> nhimg virng chuyen tiep giira Idp oxy hoa va Idp thieu oxy, ndng dg nifrit cd the cao mpt each<br /> bit thuong bdi nitrit la san pham trung gian ciia qua trinh khir nifrat bdi vi sinh vat frong dieu<br /> kipn oxy thip (Martin, 1968; Grasshoff, 1967) /3, 51. Nhu vay, ndng dp nitrit va bien thien cua<br /> chiing chimg td vyc nude nghien ciiu d frong dieu kien oxy boa.<br /> <br /> Bang 2: Thdng ke ndng dp mu6i dinh du>vng trong nu'O'c<br /> Mua khd Mua mu'a QCVN-<br /> TT Y4ut6 Thdng ke 2008 IM<br /> (n = 97) (n = 90)<br /> Amon (iJgN/l): Dao dpng 2,63-31,40 0,02 - 77,83<br /> 1 100 (*)<br /> NHs. NH/ Trung binh 12,12 ±7,89 13,30 ±14,99<br /> Nitrit: Dao dpng 0,03-6,53 KPH - 6,95<br /> 2 20 (**)<br /> NO2 (iJgN/l) Trung binh 2.08 ±1,66 1,67 ±1,68<br /> Nitrat: Dao dOng 2,05 - 50,73 KPH-13,27<br /> 3 5000 (**)<br /> N03-(ugN/l) Trung binh 8,76 ±6,62 1,50 ±1,99<br /> DIN Dao dpng 9,54 - 83,44 0,24 - 83,43<br /> 4<br /> (ijgN/i) Trung binh 22,96 ±11,20 16,47 ±15,65<br /> Photphat: Dao dpng 1,56-15,92 0,79-21,55<br /> 5 200 (")<br /> P04'-(ugP/l) Trung binh 6,28 ± 3,27 10,24 ±5,49<br /> Silicat: Dao dpng 80,93 - 989,44 86,12-1968,34<br /> 6<br /> SiOi'-(ugSi/l) Trung binh 295.28 ±159,74 500,09 ±414,17<br /> Dao dpng 2,74 - 48,56 0,11 -46,70<br /> 7 Ty so [N]/[P]<br /> Trung binh 10,59 ±7,73 4,08 ± 5,29<br /> Ty so Dao dpng 0,18-4.03 0,01 - 50,37<br /> 8<br /> Am6n/(nitrit+nitr^t) Trung binh 1,29 ±0,89 8,49 ± 9,82<br /> Dao dpng 9,60-134,08 5,25-135,78<br /> 9 Ty so [Si]/[P]<br /> Trung binh 54,18 ±32,31 52,27 ± 37,86<br /> Ghi chii:<br /> - (*): QCVN-lO/2008/BTNMT: Quy chudn ky thuat quSc gia vi chdt luang nude biin ven bd (Tieu<br /> chuan dung cho nuoi trong thuy san va bao ton thuy sinh).<br /> - (**): QCVN-08/2008/BTNMT: Quy chudn ky thuat quia gia vi chdt luang nude mat (Tieu chudn<br /> diing cho bao ton thuy sinh).<br /> Tieu ban: CONG NG'HE SINH HOC Bl£N VA MOI TRU'CNG 425<br /> <br /> <br /> Bang 3. Biln thien ndng do mudi dinh du-d-ng theo chu ky ngay dem<br /> <br /> <br /> TT Y^utd i j i o c p n g (n = 30) Trung binh<br /> 1 NHs, NH4* (iJgN/l) w,81 -5,92 3,21 ±1,26<br /> 2 NO2 (ijgN/i) 0,05 - 7,54 2,28 ±1,82<br /> 3 N03'(ijgN/l) 4,44-77,83 8,26 ±4,79<br /> 4 P04'-(iJgP.1) 0,79-19,00 13,21 ±4,93<br /> 5 SIO3'' (ijgSi/i) 8 6 , 1 2 - 1554,20 385,40 ± 387,76<br /> 6 Ty so [N]/[P] 1,33-46,70 5,46 ±8,37<br /> 7 Ty so [am6n]/[(nitrit+nitrat)] 0,61 - 13,91 3,16 ±2,72<br /> 8 Ty so [Si]/[P] 5,25 - 57,62 21,53 ±13,29<br /> <br /> <br /> 2. Bien thien nong do muoi dinh dudng theo khong gian v^ thdi gian<br /> Ngoai trir nitrit, n6ng dp cac mu6i dinh dudng: nitrat, ph6tphat, am6n va silicat dao dpng<br /> manh giiia cac tram mat rpng nhung khong the hien xu the ro rang d tat ca cac thdi diem khao<br /> sat (hinh 2a, 2b). Do khu vyc nghien ciru khong co nguon thai tap trung dang ke (kh6ng co s6ng<br /> nao chay vao) va vat chat thai vao vyc nude chii yeu la nhung boat dgng ven bd (cang, dan cu<br /> dpc bd) va fryc tiep frong vyc nude (khai thac va nudi hai san) dugc b6 fri gan nhu frai rpng<br /> Ichip viing nen phan b6 cac yeu t6 dinh dudng theo phuang ngang khong the hipn dac trung ro<br /> net. Trao d6i nude d day phu thupc che dp trieu nen che dp trieu la yeu t6 thuy dpng lye duy<br /> nhat chi phoi birc tranh phan bd dinh duong.<br /> Biln dgng n6ng dp cac chat dinh dudng theo phuong thang dimg cung kh6ng cd xu hudng<br /> ro ret (hinh 3). Trong dieu kien vyc nude nghien ciru, do nguon dinh dudng cung cap chii yeu la<br /> ngu6n npi tai, khong co dong luc dja dang ke va dp sau khoi nude con nam trong tang quang hgp<br /> uu the (dp sau kh6i nude trong khoang 35m) nen phan bo thang dirng cung khdng co dac trung<br /> ro net.<br /> <br /> <br /> <br /> <br /> Hinh 2a. Phan b6 va biln thien ndng dp mudi dinh du'ang trong mtia khd<br /> 426 Tuyln t^p HQi nghj KHOA HOC TOAN QUOC V£ SINH HQC B | £ N VA P H A T T R | £ N B £ N V & N G<br /> <br /> <br /> <br /> 35 -1<br /> 30 • Nitrat<br /> 25 • .•Viiiou<br /> - S? DPh6tph.it<br /> • Sihc-it<br /> 1"C 20<br /> 15<br /> 6-a.<br /> <br /> <br /> MJi<br /> 10<br /> .1^<br /> 0<br /> AlldilJiAAAJlAllii LI LMil I J LI l j I I I<br /> 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4<br /> <br /> 20.102006 2M0.2lX)6 22 102006 24.10.2006 08 11.2006 1811.2006<br /> Ti^m va u^T tltu uinii<br /> <br /> Hinh 2b. Phan bd vd biln thien ndng dp mudi dinh du'd'ng trong mua mu'a<br /> <br /> Ham Ii/c'ng dinh di/ang (ugN/l) Ham Icrcrng dinh di/&ng (ugSi/l)<br /> Ham li/grng dinii dir&ng (ugN. P/l)<br /> 0.00 500.00 1000.00 1500.00 2000.00<br /> 0.00 20.00 40.00 60.00 0.00 1000 2000 30.00 40.00<br /> <br /> <br /> - Ph6t phat<br /> - Ni trat 10 •<br /> (m)<br /> <br /> <br /> <br /> <br /> S-<br /> Ol<br /> c<br /> 1-<br /> 30-<br /> "•/^<br /> 40 40- |—•—Silicj<br /> <br /> <br /> <br /> Hinh 3. Biln thien ndng dp mudi dinh du'ang theo dp sau<br /> <br /> <br /> Biic franh dao dpng ngay dem ciia nong dp muoi dinh dudng (bang 3, hinh 4) cho thiy: dao<br /> dpng cua cac yeu t6: ph6tphat, silicat, am6n va nitrat co xu hudng tuong ty nhau va cac dinh cao<br /> n6ng dp ciia chiing deu roi vao ban dem - thdi gian ma qua trinh quang hgp da dimg lai (tir 18h<br /> den 6h sang h6m sau). Xem xet dao dpng eua n6ng dp muoi dinh dudng va thuy trilu theo chu<br /> ky ngay dem, co the nhan thay rang, khi thuy frilu dat eye dai, nong dp muoi dinh dudng trong<br /> vyc nude CO xu hudng giam, mac dii khoang thdi gian dd qua trinh quang tdng hgp da dimg l?ii<br /> (tir 18h din 24h).-Dilu nay chimg td, ngoai boat dpng quang hgp, bien thien dinh dudng d vyc<br /> nude ven bd Cam Ranh - Binh Ba con chju sy chi phoi dang kl cua thuy frieu. Khi frilu len,<br /> kh6i nude bien ngoai khoi vdi n6ng dg dinh dudng thip di chuyen vao vjnh pha loang vdi khoi<br /> nude frong vjnh vdi n6ng dp dinh dudng cao da lam cho n6ng dp dinh duong frong vyc nude<br /> giam. Biic franh dinh dudng theo chu ky ngay dem la kit qua chi phoi tong hgp cua qua trinh<br /> quang hgp va che dp frieu eiia vyc nude.<br /> Tieu ban: C O N G NGHE SINH HQC BI^N VA M 6 I TRLCONG 427<br /> <br /> <br /> <br /> 25 -<br /> <br /> ^ - " ^<br /> w. 20 •<br /> <br /> • B •' f^l UHt<br /> ^ M.^ 1?<br /> — A — .A. lllOU<br /> <br /> Ill 10^ " "rllOipU;!!<br /> <br /> • « o • *. ~ oi u cat<br /> --•—Trial<br /> S U'C^ 1<br /> <br /> <br /> ] 2 3 4 .\ , 6 7 8 9<br /> Tlio1glaii(0bs 3h. biM dm hi 12h)<br /> <br /> <br /> Hinh 4. Bl§n thien ndng dp mudi dinh du^ng toan cpt nu>6c theo chu ky ngay dem<br /> t^i tram 3<br /> <br /> d quy md thdi gian Idn hon (frong khoang 30 ngay), tap hgp dii' lipu bien thien n6ng dp<br /> muoi dinh dudng (bang 2, hinh 5a va 5b) the hipn sy uu the ciia amdni so vdi cac thanh phan<br /> mudi dinh duong khac frong su6t tien trinh khao sat. Am6ni la thanh phan chiem ty Ip Idn nhat<br /> frong s6 3 muoi dinh dudng chiira nita (am6ni, nitrit, nifrat) trong ca 2 miia (bang 2, hinh 5a va<br /> 5b). Mpt mat, do am6ni khong phai la thanh phan toi uu cua thyc vat n6i trong chpn lya nen khi<br /> thuy vyc cd mat nifrat thi thyc vat phii du chii yeu hap thu nitrat frong qua trinh quang hgp 14, SI.<br /> Mat khac, thiiy vyc nghien cim chii yeu nhan ngu6n nude thai tai ch6 nen nude thai mdi chi frai<br /> qua thdi gian dau tien cua qua trinh khoang boa va do vay, amdni se la thanh phan uu the frong<br /> cac muoi dinh dudng nito v6 co trong nude. Ngoai ra, biic tranh dao dpng trong 30 ngay edn<br /> xuit hipn nhung thdi diem n6ng dp am6ni kha cao so vdi nitrit va nifrat va cung la thdi diem dp<br /> cao myc nude thuy trieu kha thap: nhiing thdi diem trieu nit, bat dau len hoac la trieu yeu. Do<br /> ngudn thai xuat phat tir dat lien nen khi nude rong, ngu6n thai dugc dua tir vimg ven bd ra khoi<br /> lam cho nong do eiia chiing trong nude gia tang va ngugc lai, khi frieu cao do sy pha loang ciia<br /> khoi nude ngoai khoi nen lam n6ng dp ciia chiing frong nude giam. Ngoai ra, dao dpng ciia n6ng<br /> dp am6ni con phy thupc vao thdi diem nhan cac ngu6n thai chinh cua thiiy vyc frong ngay, thdi<br /> gian vat chit thai di vao vyc nude va frang thai oxy hoa-khir ciia thuy vyc.<br /> Cd thi noi, ndng dp nifrat d vyc nude nghien cim kha thip trong ca hai miia. Theo nhieu tac<br /> gia, mac dii trong dieu kipn pE vugt qua 12 va pH frong khoang 7 thi nifrat la dang 6n djnh nhat<br /> ciia nito vo co hoa tan frong nude nhung nong dp ciia chiing se rat thap ngay sau qua trinh quang<br /> hgp manh frong vyc nude vi qua trinh nay freu thu phan Idn photphat va nifrat c6 frong thiiy vyc<br /> 14, 5, 8/. Vi gia frj mudi dinh dudng d day dugc khao sat tai nhimg ting nude co nong dg<br /> chlorophyll-a eye dai nen phan Idn lugng nifrat da dugc sir dyng cho qua trinh t6ng hgp hihi co<br /> bdi thyc vat quang hgp cd frong m6i trudng trudc do.<br /> 428 Tuyfen tgp Hpi nghi KHOA HOC TOAN QUQC Vfe SINH HQC BI^N VA P H A T TRifeN BfeN \J\JHR<br /> <br /> <br /> <br /> <br /> i£.<br /> o<br /> <br /> <br /> if<br /> o *<<br /> <br /> I'I<br /> i tio<br /> a.i<br /> t<br /> £ l.o .<br /> <br /> lie •2 £ 2 0 •<br /> -• o<br /> .3 2<br /> l.t S .o.<br /> a 10 •<br /> .a<br /> Q<br /> £<br /> s .3<br /> .3 ^ = 0 •<br /> * 0<br /> ' 1 122 I 2 4'1 0 11 8 20'10 21/10' I 2 2 1' 0 l 2 4 , 1l 0 8 11 1 18/11<br /> 20 10 21 10 10 8 11 11 1 1 1 1<br /> 1 .<br /> Tl fljll 2<br /> Tr?m 1<br /> Tr^lln vii ii;cci^y rliu inMn<br /> T1i'»ia vii u e ^ y rbn msta<br /> <br /> i<br /> .