KHOA HOC C 6 N G N G H |
MOI LIEIV HE GILTA CHAT LUOIVG IVUO€ M A T V A THAIXIH PHAIXI PHIEU 5IIVH THUC VAT TAI
B A C V A M I \ 1 A 0 , AIM GIAIXIG
Nguyen Thanh Giao^
TOMTAT
De tai duoc thuc hien nham tim hieu moi lien he giiia thanh phan phieu sinh thuc vat va chat luong nuoc o khu vuc kiem soat lu Bdc Vam Nao, An Giang. Ba mlu phieu sinh thuc vat (VNl, VN3, va YN5) duoc thu vdto thang 3 va thang 9 nam 2018. Cac miu nude (VNl, VN2, VN3, VN4, va VN5) cung dupc thu trong thing 3 va thang 9 tir nam 2015 den nam 2018 de danh gia chat luong nude va lam ca s6 danh gia mdi ben he giiia phieu sinh thuc vilt va chat luong moi trudng nude tai cac vi tri VNl, VN3 va VN5. Ket qua phan tich cho thay, chat lirong nuoc tai khu virc nghien cmi bi 6 nhiem hiru ca do DO thap va TSS, COD, BOD5 cao hon so voi Quy chuan ky thuat Qudc gia ve chat luong nude mat (QCVN 08-MT:2015/BTNMT, cpt Al). Ben canh do coliffom trong nude d khu vuc cung vupt quy chuan. Ket qua phan tich phieu sinh thuc vat cho thay nganh Eugienophyta, Chlorophyta. Cyanophyta, chiem ti le cao lin lugt la 23,9%; 22.8%; 22,8%. Day la cac nginh tao chi thi cho moi trudng nude bi 6 nhiem hiiu ca phii hap vdi k^t qua phan tich ly hoa. Chi sd da dang smh hoc Shannon-Weiner (HO tai cac vi tri khao sat dao dong tir 0.569-2,580 cho biet mdi trudng nuoc dang d tinh trang o nhiem nhe (trong miia mua) den 6 nhiem nflng (trong miia kho). Tai cung vi tri thu miu chi sd WQI (4-37) cho thay chat luong nuac tir 6 nhiem vira den 6 nhiem nang, khong the hien ducw: su bi^n d6ng theo miia ciia chiit luong nuac. K^t qua nghien ciiu cho thay chi so sinh hoc H' va chi sd WQI c6 su khac nhau trong chi thi chat lupng nude ciia thuy vuc nguyen nhan la do phieu sinh thuc vat con chiu tac dong cua thdi tiet, sinh vat tieu thu. Do do, quan trdc chat luong nude can duac tien hanh tren co sd ket hgp giiia ly, hoa vdi quan trac phieu sinh thuc vat.
Tir khda: Bdc Vam Nao, chdt luong nuoc, chl sd chdt luong nude, chisdda dang sinh hoc, dnhiimhuuco;
phiBu sinh thuc vit
1. BAT VAN BE Chinh phii Viet Nam (GoV) ddn Chinh phu Uc (Go^
, _. , , . , . * ^ , . T.. XT - "iiTfi 1992, du in tien kha thi dau tien va nhiem vu An Giang la tmh dau nguon phia Tay Nam cua ^. ...^, =• . '. ^i . r.^ ,,. x, ^-.-.z ,_i t • _ _, ^ ,^ ^_ ,_ _.__ R*= Tr=__ j=_. Ii „=. thiet ke cho cac de an Bac Vam Nao da hen hinh vao nam 1993 va 1994. Tir nim 2002 d^n 2007, du in kiem soat nude Bic Vam Nao (NVNWCP) da dupc trien khai 6 cac huyen Tan Chau va Phu Tan, tinh An Giang. Bic Vim Nao trdng giong nhu mOt hon dao dupc bao hoc boi song Tien vi song Haiu, ndi vdi nhau bing he thdng kenh muong phan chia cic phan lan can cua dao. Muc tieu cua du in li hd tro tinh An Giang thiet lap va van hanh mdt he thdng quan ly dat nuoc va la ha luu song Me Kong, day la mpt
trong bdn tinh thuoc vimg kinh te trong diem dong bing sdng Ciiu Long. An Giang con duoc xem la dia phuong hpi tu rat nhieu tiem nang phat trien nong nghiep, thuong mai, dich vu, du hch. Su phat trien hien nay dang gay siic ep len mdi truong, lam niy sinh cac van de ve 6 nhiem, dac biet la 6 nhiem ngudn nuoc va nhieu van de ve moi truong cap bach
da va dang dien ra, anh hudng d^n chat luong cudc , . . . ', ' D i ' T r . _ M Li ' - a « - , , , \ , - , . , , ... nuoc hieu qua o Bac Vam Nao ben vung ve mit xa song va su phat tnen ben vumg, nhat la trong dieu . . . . '.. . . . . . , „ „^ 1 • L ^.- .. , , . ' , ^ 1 1 . , ' f , - . hoi va moi tirrong, co Ipi cho nen kinh te dia phuang kita bita m khi hau toan cau dang dien ra phuc tap. ^^^ ^j j^a xoa doi giam ngheo. Han nOa, du an nham Du an Kiem soat nuoc B8c Vam Nao bat nguon t^ y _,^^ ^^ ^.^^ .^ ,.^^ kinh t^ va xa hoi cho cOng d6ng tuong phat trien trong Quy hoach tong the dong ^ ^ ^^^ _j,.( [j bj„ ^^ ^^, ^^^ ^^ ^^^^ ^^^
bang song Ciiu Long do Cong ty Tu van Ky thuat Ha ^^^ ^ ^ ^i .^ p^ .j ^^ ly nuoc va dat (Nghif n Lan (NEDECO, 1993) hoan thanh. Theo d^ xuat cua ^^ ^^ ^^ ^^„ j „ ^ ^^^ ^ ^ ^ ^^ ^^^ ^ .^^ ^,__^
CWMPs, 2015). Phita sinh thuc val thupc nh6m ' Khoa Moi truong vil Tai nguyen Thien nhien, Tmimg Bai Phieu sinh vat, la mat xich d4u tien trong chu6i thlK hpc Can Tho
Email: [email protected]
an tir nhien cua tiiiiy vuc. Day la ngudn tiiuc in ti;
KHOA HOC C d N G NGHE
nhien rat quan trpng cua cic loai phieu sinh dpng v^t, c i hot, giap xie va au trimg torn, cua, ca, nhuyen th^ hai manh vo,...Phieu sinh thuc vit con cung cap phan Ion lupng oxy trong nuoc t^o mdi truong giau oxy cho ca sdng vi phat tnen (Lam My Lan, 2010).
Ngoai ra, phieu sinh thuc vat con c6 vai tro quan trpng la chi thi moi truong niroc. Khi moi truong nuoc thay doi se inh huong den su phan bd cua phieu smh thuc vat. Theo Heisler et al (2008), co moi tuong quan chit che giiia phu duong hoa ctia moi truong nuoc ngpt va nguon dinh duong do su tac dong cua con nguoi nhu nuoc thai sinh boat, nuoi trong thiiy san, ndng nghiep, cdng nghiep va cdng thai, dieu nay se tic ddng den phieu sinh thuc vat.
Nghien ciiu nay dupc thuc hien nhim danh gia mdi quan he cua chat lupng nude va phieu sinh thuc vat phuc vu quan trie moi trudng nuoc mat tai Bic Vam Nao.
2.PHUDN6PHAPIUGiniCUU 2.1. Thu v i phin tich m i u nu6c
Cac miu nuoc dupc thu thing 3. 6 va 9 trong giai doan tir nim 2015 - 2018 t ^ 7 dia diem ky hieu VNl- VN7 nhu trong hinh 1.
(WQL Water Quality Index) dugc linh toan dua tren cong thiic (1) (long cue Moi truong, 2011)
Hinh L So dd vi tri thu miu Cac miu dupc Iim tru trong chai nhtra co the tich 2000 mL v i dupc van chuyen trong mpt thimg da d^n Phdng thi nghiem Phan tich Moi trudng, Khoa Mdi tiiiong va Tai nguyen Thien nhien, Truong Dai hpc Can Tho. Chi sd pH, tong chat rin lo lung (TSS, nig/L), nhu cau oxy smh hoa (BOD, mg/L), nhu cau oxy hda hda hpc (COD, mg/L), chat dinh duong (NH4*_N, NOs.N, P04^_P, mg/L) da duoc phan tich tiieo phuong phap tieu chuan d^ kiem tra nuoc va nuoc thai (APHA, 1998). Chi sd chat lupng nuoc
WQI = '^^V^_Z^._^^\VQ!^ WQI,\ (1) Trong do WQI, la WQI tinh cho BOD. COD, NH4*-N, P O / -P; WQI, la WQI tinh cho TSS; WQI, la WQI tinh cho pH. WQI nam ti-ong khoang tir 0 den 100 phan chia chat lupng nude thanh nam cap. Cap 1 (100> WQ1> 91) la chit luong nuoc tdt c6 the dupc su dung cho muc dich cap nuoc. Cap 2 (90> WQI> 76) cung dupc sir dung de cap nude cho smh boat nhung can cd bien phap xii ly phii hpp. Cap 3 dinh cho tudi tieu va cac muc dich tuong tu khac (75> WQI> 51).
Cap 4 (50> WQI> 26) la nude phii hpp cho van chuyen va cac muc dich tiJong dtrong trong khi Cap 5 (25> WQ1> 0) dupc coi la nuoc bi d nhiem nang ma cin CO bien phap xu ly thich hpp.
2.2. Thu v i phin thich mSu phieu smh thi^ v^t Cac miu thuc vat phii du dupc thu vio thing 3 va thing 9 tai ba vi tri thu mau nude (VNl, VN3 v i VN5) nam 2018 bing each loc 200L nude qua ludi kich thude 25 pm. Cac miu co die dupe dat trong Ip 110 mL va cd dinh vdi formaldehyd 24%. Phan tich dinh tinh duoc thuc hien bing kinh hien vi trong vat kinh 10X-40X va hinh anh cua thuc vat phii du dupe thuc hien de xac dinh cac dac diem hinh thai va cau tnic va phan loai theo Tien va Hanh (1997); Ho (1969); Tuyen (2003); Fernando (2002); Reynold (2006). Cac miu phan tich dmh lupng dupc thuc hien bing each dem timg thuc vat phii du theo phuong phap cua Boyd vi Tucker (1992). Mat dp cua thuc vat phii du dupc tinh theo cdng thiic (2):
„ _ y-Vj.-iooo .V->l-*/r
Trong do: Y l i mat dp thuc vat phii d u / (ca the/ht); X la so lupng ca the thuc vat phu du trong cac td bao dupe dem; V^ la the tich miu cd die (mL);
N la sd lupng te bao duoc dem; A l i the tich cua cac te bao dupc dem (1 mm^ va Vj la the tich nuoe duoc thu thap (mL).
Su da dang cua sinh vat da dupc kiem ti-a bing cich tinh toan chi sd da dang Shannon-Wiener (H") theo cong thtrc (3):
H=-I.p,.ln{p.^
Trong do: pi = ni/N; in la sd cua ca nhan thii i; N la tong so luong ca the trong cac mau. Chat Iuong
KHOA HOC CONO NGHt nuoc Alloc phan chia theo ba miic do 6 nhiim Aaa
tren cac gia tri H'. H'>3 cho thay chat luong nuoc tot hoac nuoc khong hi 6 nhijm. 1<H'<3 cho thay 6 nhi^m nuoc vira phai, H'<1 cho thay nuoc hi 6 nhi^m nang (Wilhm and Dorris, 1968).
8.1ft QUA THAO UliiN
3.1. Ch^t lupng nude mat Bac Vam Nao giai doan 2015-2018 qua cac chi tita \f, h6a hpc
3.1.1. Nhiet do
Nhiet dp nuoc mat a Bac Vam Nao trong giai doan 2015-2018 khong co su bien dpng nhita giua cac vi tri khao sat qua cac nam vol khoang dao dong tit 27,4±0,91-31,3±0,98°C va trung binh 29,4±0,73"C (Hinh 2). Nhiet do tmng binh giira cac nam chenh lenh tuong doi thap voi nhiet dp cao nhat vao nam 2018 (29,3°C) va thip nhat vao nam 2017 (28,6''C).
Nhin chung nhiet dp trung binh tai khu vuc nghien ciju tuoTig ddi cao gop phan anh huong den kha nang hoa tan cua cac khi trong nuoc dac biet la oxi, tao moi truong thuan Ipi cho nhieu loai tao phat trien boi cac loai thuy sinh vat thuong phat tri^n tot a nhiet dp tir 25-32°C (Bp Thiiy san, 2004). Tuy nhien khi nhiet dp cang cap qua trinh phan giai chat huu co cang manh, toe do dong hoa ddc to tang va ngudng gay chet ciia cac loai sinh vat co th^ dat dupc nhanh hon (Canning etal., 2019).
Hinh 2. Di6n bi^n nhiet dO o Bdc Vdm Nao giai do^in 2015-2018
Ghi chu: Cac ky ta a, b, c chi sir khac biet co y nghia thong ke gitra cac nam a miic y nghia 5%: x, y, z str Idiac biet CO y nghia giira cacdiSin tiongnam.
3.1.2. pH
pH trong nude tai cac vi hi khao sat qua cac nam dao dpng tii 6,96+0,31-7,43+0,21, trung binh la 7,13±0,06 (trung tinh) va deu nam trong gioi han cho phep cua QCVN 08-MT:2015/BTNMT (Cpt Al)
(Hinh 3). Gia tri pH kha on dinh qua cac nam va cic vi tri trong cimg thdi gian thu mSu da gop phan tjo dieu ki^n va mdi truong thuan Ipi cho cac loai sinh vat va thiiy smh thuc vat dS dang thich nghi va phit hien. D6ng thoi ket qua phan tich cung phii hpp voi nghien ciiu ciia Le Van Cat va ctv. (2006) khi gia tri pH cua nupc m$t thutmg nam trong khoang 5-9.
Hinh 3. Dien bi^n pH 6 B ^ Vam Nao giai do^n 2015-2018
Ghi chu: Cac ky tii a, b, c chi sir khac bi^t cd y nghia thong ke giira cac nam amtrcy nghia 596; x, y, zstr kh^c biet co y nghia gitra cac diSm tiong nSm.
3.1.3. Tdng ch^t r^ lo Idng
La khu vuc dupc he theng thiiy Ipi ki^m sodt, dong chay nho, tinh chat biin day it xao hOn nen thanh phan chiit r ^ la liing p Bac Vam Nao chu ye'u la cac sinh vat phii du vdd ham lupng TSS dao dOng ttr 44±22,11-94,3±15,97 mg/L va hung binh la 65,8+3,88 mg/L (Hinh 4), cao ban k^t qua quan trac vao thang 3/2015 tai khu vuc sdng Hau la 53 mg/L (Bao cao hien trang mdi h-u6ng tinh An Giang giai doan 2011-2015, 2015).
Hinh 4. DiSn b i & TSS & Bac Vam Nao giai dosn 201M018
Ghi chii: Cac ky tir a, b, c chi sir khac bi(t co y nghia thdng ki giua cac nam a mucy nghia 5%:x,y.
z su khac biet CO y nghia giua cac di^m tiong nam.
Ham luong TSS cd su suy giam theo thdi gian vdi ham lupng trung binh cao nhit la 'I4.3+19,6 mg/L NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 9/2020
KHOA HOC CONG N G H £
(nam 2015) va thap nhat la 45,3+9,5 mg/L (nam 2018). Mac dil nim 2017 him lupng niy tuong doi cao hon nim 2016 (67,5>62,5 mg/L) nhung su khac biet nay khong cd y nghia ve mat thong ke (p<0,05).
Giua cic vi tri trong cung thdi diem khao sat gia tri TSS bi^n dpng khong ding k^. T ^ vi tri VN4 ham lupng TSS CO gia tri trung binh thap nhat (61,2+20,5 mg/L) qua 4 nam va cao nhat la 70,8+15 mg/L (VN6). TSS cd lien quan rat mat thiet den kich cohat va tdc dp ling ciia cac hat lo lung ti-ong nude (Boyd, 1998) vi tiiy thudc vao dac diem ciia timg khu vuc khao sit da tao nen su chenh lech v^ ham lupng TSS tai timg vi tri. Tuy nhien tai t^t ca cac diem khao sat ham lupng TSS deu vugt qui gidi han cho phep cua QCVN 08-MT:2015/BTNMT (cot Al) tii 3,06 - 3,54 Ian da chiing to chat lupng nude tai day dang 6 nhiem.
3.1.4. Oxy hda tan
(D0>6 mg/L) va su bien dong nay hoan loan phii hpp voi dien bien chung ciia chat lupng nuoe tai vimg nghien ciru, noi co nong do BOD va COD cao, vupt nguong cho phep.
3.1.5. Nhu cau oxy hoa hgc
Ham luong COD tai cac vi tri thu mau co su bmn dpng qua cac nam (dac biet la nam 2015 va 2016) vdi khoang dao dong tii 10,7+2,52-26+12,1 mg/L, tiling binh la 17,1+2,18 mg/L (Hinh 6). Vi hi VN2 co him lupng COD thap nhat 6 hau bet cac nim vdi gii tri trung binh la 13,8+2,41 mg/L va cao nhat tai vi tri VN7 (20,3+2 mg/L). So vm QCVN 08-MT:
2015/BTNMT (Cot Al) tiii ham lupng COD tai tat ca cac diem khao sat deu vupt gidi ban cho phep (>10 mg/1). Tir day cho thay nguy co 6 nhilm hiiu co tai khu vuc Bic Vam Nao ciing nhu xu hudng gia tang dan miic dp d nhiem khi ham lupng COD trung binh tir 2015-2018 Uen Iuc gia tang vdi gia tri lan lupt la 13,7; 15; 18,2; 21 mg/L. Su bien dpng niy chii yeu xuiit phat tir sir trao doi nuoc theo chu ky, boi ling cic chat huu co trong nuoc ciia he thdng thiiy Ipi Bic Vam Nao khi lu ve.
Hinh 5. Dien bien DO a Bic Vim Nao giai doan 201S-2018
Ghi chii: Cac ky tua, b. c chi su khic biet cd y nghia thdng kegida cic nam dmiicy nghia 5%:x, y 2 Sir khac biet coy nghia giua cic didm tiongnam.
Ham lupng DO trong nuoc 6 Bic Vam Nao cd nhi^u bien dong voi gia hi trung binh cao nhat vao nim 2015 (5,32+0,495 mg/L) va tiiap nhat vio nam 2016 (3,56±0,575 mg/L). Nam 2018 h i m Iuong DO hrong ddi thap hon nam 2017 (4<4,13 mg/L) va cao hon nam 2016 nhung su bi^n dpng niy la khong ding ke (Hinh 5). O hau h^t cac nam (hir nam 2015) su bi^n dpng DO giiia cac vi ti-i khio sat khong cd nhi^u khic biet vdi ham lugng hung bmh cao nhat t9i vi til VN4 (4,79+0,607 mg/L) va thap nhat la VN7 (3,88±0,802 mg/L). Tai cic vi tii VN2, VN4, VN5 him lupng DO vac nam 2015 cao ding ke so voi VNl. Vdi khoang dao dong tir 2,73+1,36-5,74+0,5 mg/L (tiimg binh: 4,25+0,8 mg/L) da cho thay h i m lupng DO tai day vin chua dat quy chuan cho phep
Hinh 6. Di^n bi^n COD o Bic Vam Nao giai dogn 201S-2018
Ghi chii: Cac kytua,b,c chi su khic biet cd y nghia thdng ke gida cac nam a muc y nghia 5%; x, y, z su khac biet cd y nghia giua cac diem tiong nam.
3.1.6. Nhu cau oxy sinh hda
Bidn dong him lupng BOD va COD d' Bic Vim Nao giai doan 2015-2018 co nhieu net tuong ddng khi him Iuong BOD trung binh deu co xu hudng tang lien tiic (8,90+1,58-13,7+1,86 mg/L) qua cac nim v i tiiap nhat tai VN2 (9±1,63 mg/L), cao nhat t ^ VN7 (13,1+1,37 mg/L) cung nhu khong co sir bi^n dpng Idn giiia cac vi tri khio sat vao nam 2017 va 2018 (Hinh 7).
KHOA HOC CdNG NGHE
Hinh 7. Dien bi^n BOD o Bic Vim Nao giai doan 2015-2018
Ghi chu: Cac ky tua, b, c chi sir khic bidt cd y nghia thdng kd gida cic nam a mucy nghia 5%;x, y, z sukhic biet cd y nghia giim cac didm tiongnam.
Ham lupng BOD trong vimg nghien cuu tuong ddi cao (do nude thii hiiu co tir hoat dgng sin xuat nong nghiep, smh hoat) vdi gii tri trung binh:
11,11+1,41 mg/L va dao dong tii 6,67+1.53-16,7+7,51 mg/L. Su vupt nguong gioi ban cho phep cua QCVN 08-MT: 2015/BTNMT (Cot Al) ve h i m lupng BOD tai tat c i cic dia diem thu miu cung gdp phan phan anh miic dp 6 nhiem hiiu co tai day ciing nhu kha ning tu lim sach cua nguon nuoc kem, dieu nay phii hpp vdi ti le BOD/COD= 0,65 tai khu vuc, tuy nhien ty sd niy ludn thay ddi v i tiiy thudc vio tinh chat ciia nguon 6 nhiem (Pham Van Thuong va Ding Dinh Bach, 1999). Mat khac h i m luong BOD cang Idn se cang lam giam lupng DO trong nude, gay anh hudng ddn cac loai sinh vat (Boyd, 1998).
3.1.7. Ham lugng amoni
Him lupng N_NH4'^ trong nuoc a Bac Vam Nao giai doan 2016-2018 kha cao (trung binh 0,48+0,14 mg/L) dao dpng tir 0,02+0,02-0,76+0,50 mg/L (Hinh 8). Tai h^u het cic vi tri khao sit ham Iuong N_NH4*
cd xu hudng gia tang vao nira 2017 (die biet la tai cac Vl tri VNl, VN2 v i VN4) v i khdng cd nhieu bien doi vao nam 2018 do su trao ddi nude cua he thong thiiy Ipi Bac Vim Nao vol ben ngoai diln ra khong lien tuc. So voi QCVN 08-MT:2015/BTMNT (Cot Al) hau het h i m lugng N_NH4'' tai cac vi tri nghien ciiu deu vugt gioi han cho phep (ngoai trir cac diem VTl, VT2 va VT4 vao nam 2016). Dieu nay chiing td nude trong khu vuc Bic Vim Nao da hi 6 nhiem amoni din d^n thieu oxy gay dpc tinh cho cic loai thuy sinh vat (Le Vin Cat va ctv, 2006). Mdi nguy hiem amoni cing cao khi gia tii pH >8 (Pham Qudc Nguyen vi ctv., 2014) phii hop vdi xu huong ting pH tai cic vi hi khao sit qua cic nam (Hinh 3).
Hinh 8. Dien bien amoni b Bic Vim Nao giai do^n 2015-2018
Ghi chu: Cac ky tii a. b, c chi su khac bidt cd y nghia thdng kd gida cic nam dmiicy nghia 5%;x, y, z su khic bidt cd y nghia giira cic diem trongnSm.
3.1.8. Ham limng nitrate
Him lupng nitrate tai khu vuc Bic Vim Nao tuong doi thap (trung bmh: 0,084+0,056 mg/L) va co xu hirong giam dan trong giai doan 2015-2018 vdi gia tri trung binh qua cic nam dao dpng tir 0,036+0,01- 0,113+0,04 mg/L. Tai cac vi tri khao sit ham lupng nitrate cd nhieu bien dgng vi cao nhat tai vi tri VN3 nam 2016 (0,30+0,32 mg/L), tiiap nhat Ii 0,03±0,02 mg/L tai cac vi tii VNl, VN2 va VN4 vio nim 2018 (Hmh 9). Ket qui phin tich cung cho thay su suy giam ve him lugng nitrat tai viing nghien ciiu khi ham lupng niy tai song Hau vio nim 2015 li 0,16 mg/L (Bio cio hien trang moi truong tinh An Giang giai doan 2011-2015, 2015). Tuy nhien su bien doi niy hoan toan phti hpp vdi ket qua phan tich DO thip, COD vi BOD cao trong nude (moi truang thich hpp thiic d^y qua trinh khii nitrate). Nhin chung, him lupng nitrate tai tat ca cic vi tri khio sat deu nhd hon 3 mg/L va n i m trong gioi ban cho phep ciia QCVN 08-MT:2015/BTNMT (Cot Al).
Hinh 9. DiSn bi^n nitrate b Bic Vim Nao giai do^n 2015-2018
Ghi chii: Cac ky tu a. b, c chi sukhac bidtcdy nghia thdng kd gida cic nim a muc y nghia 5%; x. y, z su khac bidt cd y nghia gida cicdtdm tivngnim.
KHOA HOC CONG N G H £
3.1.9. Him limng orthophosphate
Him Iuong P_P04^ trong viing nghien ciiu co nhi^u bi^n dpng (dao ddng tir 0,05+0,04-0,27+0,2 mg/L) voi h i m lupng hung binh la 0,1+0,03 mg/L, tti^p hon ket qua quan trie fren sdng Hau (0,32 mg/L) vio thing 3/2015 (Bio cio hien trang moi tru6ng tinh An Giang giai doan 2011-2015, 2015). Tuy nhien, tai hau het cic vi tri khao sit vio nam 2015 (tiir VTl) v i cac vi hi VN2 (nim 2017) va VN3 (nam 2018) h i m lupng niy vin vupt nguong gioi ban cho phep cua QCVN 08-MT:2015/BTNMT (Cot Al) (Hinh 10). Trong giai doan 2015-2018 ham \uang P-POi* tiling binh c6 xu hudng giim, tuy nhien den nim 2018 him lupng P_P04^" tai hiu het cic vi tri deu ting cao do qua trinh nia troi cic chat tir canh tac ndng nghiep tren cic mong liia quanh khu vuc cung nhu anh budng cua cac cong trinh thuy den su trao doi nude lien tuc vdi ben ngoii din den nguy co 6 nhiem cao.
trong duong nipt ciia dong val man nong: nhdm chun v i dgng vat co vii (Dang Van T'y va ctv 2018)
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Hinh 10. Dien bidn orthophosphate 6 Bic Vam Nao giai dogn 2015-2018
Ghi chii: Cac ky tu a, b, c chi su khic bidt cd y nghia thdng ke giira cic nam a muc y nghia 5%; x, y, z sukhac bidtcdy nghia giua cic diem trong nam.
3.1.10. Coliform
Mit do coliform tai khu vuc Bic Vim Nao tuong ddi cao (hung binh 47306+20739MPN/100 mL) va dao dpng tir 3.633±1.154-313.933+53.3531MPN/100 mL, vuot gioi han cho phep cua QCVN 08-MT:
2015/BTNMT - cot Al (Hinh 11). Giai doan 2015- 2018, mat dp cohform cung co nhieu bien dpng voi xu hudng giam dan vao nam 2016 va gia tang dang k^ vio cac n i m tiep theo. Sy gia ting hien dien vol mit dp cao cic vi khuan nay da cho thay ngudn nuoc dang hi 6 nhiem hiiu co v i tiem an nhieu nguy co giy benh cho ngudi do cic boat dpng san xuit, sinh hoat ciia nguoi d i n sdng ven song die biet l i cic hoat dpng chin nuoi boi cohform thuong xuat hien
Hmh 11. Dien bi^n coliform a Bic Vim Nao giai doan201&-2018
Ghi chu: Cic ky tua, b, c chl su khac biet cd y nghia thdng ke giira cic nam d muc y nghia 5%; x, y, z su khic bidt cd y nghia giira cac diem trong nam.
3.2. Die diem phieu sinh thuc vit 6 Bic Vim Nao
3.2.1. Thinh phan loai va ti'nh da dangcuaphidu sinh thuc vat
Thanh phan loii phieu smh thuc vat qua hai dot khao sat tuong ddi da dang khi ghi nhan dupc 92 loai thupc 7 nginh tao. Trong do chiem uu the li nganh tao mit (Eugienophyta) voi 22 loii (chiem 23,9%), tao lam (Cyanophyta) va tao Iuc (Chlorophyta) cung xuat hien voi 21 loii (chiem 22,8%), tao siUc (Bacillariophyta) 16 loai (chiem 17,4%), tao vong (Charopida) 10 loai (chiem 10,9%), hai nginh tao inh kim (Chrysophyta) va nganh tao giip (Dinophyta) co sd loai hien dien thap nhat voi 1 loai chiem ti le 1,1%
(Hinh 12). Ket qua phan tich da cho thay su gia tang dang ke ve sd lupng v i thinh phan loai tao d khu vuc Bic Vim Nao khi vao dpt quan trie thing 3/2018 chi phat hien dupe 6 nginh tao vdi 57 loai cung nhu chua CO su xuat hien cua nginh Chrysophyta (Bao cio ket q u i quan trie moi tnrong An Giang - dpt thing 3 nam 2018).
DCyanojAMa IChnsophla Hinh 12. Ciu tnic thinh phan loii phieu sinh thi^c
v%t
KHOA HOC CdNG NGHt Ket qua phin tich d i chi ra su khic biet ve thanh
phan loai giiia hai dot khao sat vao dot 1 (mua kho) chi ghi nhan dupc 5 nganh tao vdi 48 loii kem da dang hon dot 2 (miia mua) voi 64 loai thupc 7 nginh tao (Hinh 13). Su bidn dpng niy hoin toin phii hpp voi nghien ciiu cua Pham Thi Nggc Bich (2013), khi tai khu vuc sdng Vim Nao vao miia mua thanh phan loai tao phong phu bon mua khd (62>56 loii). Tuy nhien tiiy thugc vao su thay ddi die tinh ciia nude, thuy vin, hoic do 6 nhiem cue bd bdi die trung cua cic vi tri tai thdi diem khio sit m i su bien dpng ve thanh phan loii tao l i khong gidng nhau.
nCX'aiiophyta 0Clii>'sophyta iBaciUanophyla
iC> -^^ 'C^ <^ 'O ^"^
Hinh 13. Bi^n ddng thinh phin loai phieu sinh thip:
vat t^i cic vi tri khio s i t
Tai cac diem khao sat deu co su xuat hien cic nganh tao mdi o' dot 2 do dong nuoc mang vio (Hmh 13). Die biet la tai vi tri VNl voi su xuat hien cua hai nganh tio Chrysophyta v i Dinophyta tuong ling voi hai loii la Dlnobryon sertulana, Peridinium cmctiun cung vol su gia tang cua h i u het cic nganh tio (ngoai trir Bacillariophyta) da din den su phong phu ve thanh phan loai tao vio dpt 2 so vdi dpt 1 (44 >27 loai). Su bi^n dpng nay ciing xay ra tiJong tir tai vi tri VN5 (trir nganh Cyanophyta giam). Mac dii chi xuat hien tiiem mpt nganh Chrysophyta (loai Dinobryon sertiilari^ nhung tai day c6 sd lupng loii tao cao nhat qua hai dot khao sit (63 loai) va dpt 2 (43 loai) phong phu hon dpt 1 (34 loai). Hien dien vdi so loii it nhat qua 2 dot khao sat (41 loii), vi tri VN3 co so lupng loai tao vao dot 2 (21 loai) lai kem phong phu hon dpt 1 (29 loii) do su suy giam dang ke cua cac loii tao thupc nganh Bacillariophyta - sdng trong cic viing nuoc khong qua bi 6 nhi6m (Tnrong Hoang D a n v i eft', 2017).
Qua khio sat cau tnic vi su phin bd thanh phan loii tao o Bic Vam Nao d i cho tiiay hiu het cic nginh tao vong, tao inh kim va tao giip (phit tiien 6
ngudn nuoc nhiem man) deu xuit hien voi tan suit rat thap hau nhu d mpt diem tiiu miu. Dong thoi cic gidng loai tao cd k h i ning chiu dyng di^u kien d nhiem tiiupc cic nginh tao Iuc, tao lam v i tao mit (Pahner, 1969 hich boi Pham Manh Toan, 2012) lai chiem uu flie. Cic loii pho bien tiiudng xuat hien vdi tan suit cao h-ong hai dpt khio sit l i Euglena acus, Euglena splrogyra, Lepocinchs ovum, Phacus longlcauda, Strombomonas gibberosa, Trachelomonas hispida. Artivospira platensis, Planktothrix mbescens, Planktotiirix sp, Diatoma elongatum, Melosira granulata. Die biet la loai Euglena acus xuat hien o tat ca cac vi tri khao sat va cic loai die tnmg chi xuat hien 6 tat ca cac vi tri vao mdi dpt khio sat nhm Phormidlum sp., Quadrigula chodati (dpt 1) va Osclllatoria peromata (dpt 2). Ket q u i phan tich d i gop phan phan inh nguy co nhiem ban moi trudng nuoc tai day khi co sy phit hien manh cua cic gidng Euglena. Osclllatoria, Phacus - thuong xuyen xuat hien a thuy vyc 6 nhiem (Lfe Hiing Anh, 2008). Tren thyc te ket qua phin tich thdng sd li hoa d i cho thay nuoe tgi khu vuc nay da hi 6 nhiem do gia hi COD, BOD5 va TSS deu vupt quy chuan.
3.2.2. Matdgphidu smh thuc vat
Qua hai dpt khao sat cd the nhan thiy mat dg phieu smh thyc vat o Bic Vara Nao vio dpt 1 (miia khd) cao hon dot 2 (miia mua) v i dao dpng khi Idn vdi gii tii lan lupt la 35.949-91.094 ct/1 vi 21.672- 47.210 ct/I (Bing 1). So vdi nghien ciiu cua Phgm Thi Ngpc Bich (2013) tai khu vuc sdng Vim Nao (tii 6/2011-7/2012) vdi mat do tio la 11.196 ct/1 (miia mua) vi 21.707 ct/I (raua kho) da cho thay su phong phii ve mat do tao tai khu vyc nghien oiu cung nhu khuynh hudng sd lupng tao giim thap vao miia Iii vi tang cao vao miia khd ff)ing Ngpc Thanh vi ctv, 2002). Tuy nhien tiiy thugc vao dieu kien moi trudng, mdi quan he trong chudi tiiiic i n vi chat lupng nuoc a cic thoi diem din den sy phin bd khic nhau ve mat do cic loii tao qua cic dpt khao siL
Sy bien dgng ve mat dp tao qua hai dgt khao sat duge the hien ro nhat qua su suy giim ding kl mat dp cua cic loai Planktothrix sp., Osclllatoria tenuis, Osclllatoria thupc nginh tao lam va su gia tang hau hdt ciia cic nginh tio tai cic vi tri khao sit (tiir tie mit tai VN3) cung nhu sy tuong quan nghich giua s6 lupng vi mat do ciia nhdm tao khue va tao lam. ^\^^
dil tai cic vi tri thu miu (tni VN5) deu co su gia ting
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 9/2020
KHOA HOC CdNG NGHt ve so lupng loai tao lam (Hinh 13) nhung mat dp lai
giim manh. Trong khi do nhom tao khue lai co xu huong di ngupc lai do vao dpt 2 cac chat 6 nhiem dupc pha loang dan h-ong miia mua tao dieu kien cho cac loii Melosira granulata phat tiien manh. Sy bien dOng ve mit dp cua cic nhom tao niy din den su
khic biet Idn ve mit dp tao tai cac vi tri khao sat. Dac biet la tai VI tri VN3 voi mat do tao cao nhit vio dot 1 (94.160 ct/1) va tiiap nhat vac dot 2 (10.647 ct/I). Tai vi tri VN5 mat do tao vin cao hon so voi VNl qua c i hai dgt (Bang 1).
Bing 1. M i t dp phieu sinh thuc vit o Bic Vara Nao Nganh
Cyanophyta Chrysophyta Bacillaiiophyta Chlorophyta Charopida Eugienophyta Dinophyta Tong
Mat do (ct/1) VNl T3
35.702
-
5 232
3 7 35.949
VN3 T3 93.902
65 184
-
9 94.160
VN5_T3 90.578
212 290 2 12 91.094
VNl T9 12.350
44 1.108 8.076 10 74 10 21.672
VN3 T9 6.369
772 3.389
114 3
-
10.647
VN5T9 23.420
105 4.830 18.220 20 615 47.210 Nhin chung mat dp cac loai Cyanophyta (tio
lam) vin chi^m uu the qua hai dpt khio sit. Ddng th6i cic nginh Chlorophyta (tao Iuc) va Bacillariophyta (tio khue) cung chiem rait dp tuong doi cao. K^t qua phan tich da dit ra nhieu mdi quan tim cho chit lupng nude d- Bic Vim Nao boi sy hien dien voi mat dp cao cua cac nginh tao chi thi cho mdi tiirong nhiem ban. Cung nhu su bien dpng khdng ddng deu ve mat dp tao qua hai dpt khao sit.
3.3. Dinh g i i ch^t lugng nuoc su dyng phieu sinh thyc v$t v i chi sd ch^t Iirgng nude
K^t qua phan tich chi sd da dang H' dao dgng hi 0,569-2,58 da cho thay su da dang thap 6- khu vyc
nghien ciru vi nguon nude dang o miic tir 6 nhiem nhe den rat 6 nhiem (Bang 2). Chi so H' cho thay tic ddng cua miia den mdi truong nude rat ro ret miia mua chat luong nude tot hon miia kho. Tai cung vi tri thu miu chi sd WQI cho thay chat lupng nude tii 6 nhiem vira den 6 nhiem nang (WQI = 4-37). Chi sd WQI it cho thay su bien dpng theo miia cua chat lupng nuoe. Ket qua nghien ciiu cho thay khong co su tuong dong cao giiia danh gia chat lupng nuoc su dung chi sd H' vi WQI. Viec chi sii dung phieu sinh thuc vit dinh gii chat lupng nude cd the chua phan anh day du tinh trang 6 nhiem moi truong ciia thiiy vuc.
Diem thu mau VNl T3 VNl T9 VN3 T3 VN3 T9 VN5 T3 VN5 T9
Bang 2. Chi s6 da dang H'v4 WQ Phieu sinh thuc vat Chi sd H'
0,699 2,58 0,569 2,35 0,662 2,37
Chat luong nuoc 0 nhi&m nang
0 nhifem nhe 0 nhi6m nang
6 nhiem nhe 0 nhiSm nang 0 nhifem nhe
dia cac di^m thu m i u Thong so hoa li Chi so
WQI 4 17 12 18 37 19
Chat lirong nuoc 0 nhi^m nang 0 nhiem nang 0 nhilm nang 0 nhiem nang 0 nhilm vira Q nhilm nang 4. KETLUAN
Chat lupng nude khu vyc ki^m soat lu Bic Vim Nao di bi 0 nhiem hiiu co va cd xu huong gia tang dan mirc dp 6 nhiem do h i m lupng DO thap va BOD5, COD, TSS, NH4*_N v i Cohirom deu vuot
QCVN 0a-MT:2015/BTNMT (Cpt Al) vi co ham lupng cao vao nim 2018. Ket qua nghien cuu ve phieu sinh thuc vit da phit bien 92 loii thupc 7 nganh tio vdi s6 loai cao nhat la nganh tao mit (Eugienophyta) hep theo Ii tao lam (Cyanophyta),
KHOA HOC CdNG NGHE tao lyc (Chlorophyta), tao sihc (Bacillariophyta), tao
vong (Chargpida), tao inh kim (Chrysophyta), tao giap (Dinophyta). Vio dpt 2 co su gia tang ve sd lupng tio (48 <64 loai) va suy giim ve mat dg (35.949-91.094 ct/I > 21.67247.210 ct/I), hiy nhien cic nganh tao Iuc vi tio lam luon chiem uu the. Chi sd H' va WQI vin chua co su tuong ddng cao trong viec chi thi chat lugng nuoc vi chi sd H' cho thay chat lupng nude tii 6 nhiem nhe ddn 6 nhiem nang trong khi chi so WQI cho thay chat lupng nude tii 6 nhiem vira den 6 nhiem nang. Do do can ket hpp quan trie phieu sinh thyc vit vi cic chi tieu danh gii chat lugng mdi truong nu6c de phin inh day du ban ve tinh chat nguon nuoc.
TAI UBITHAM KHAO
1. Adam D. Canning, Russell G. Death, in Canning, Russell G. Death, 2019. Ecosystem Health Indicators-Freshwater Environments in Encyclopedia of Ecology (Second Edition).
2. American Pubhc Health Association, 1998.
Standard methods for the examination of water and wastewater, 20th edition, Washington DC, USA
3. Bg Tai nguydn vi Moi tiirong, 2015. QCVN 08- MT:2015/BTNMT Quy chuan ky tiiuat ve chat lupng nude m i t
4. Bg TTiuy sin, 2004. Quan ly chat lupng nude trcng nudi trong thuy sin. 17 trang.
5. Boyd, C. E., 1998. Water quality for pond Aquaculture. Deparment of Fisheries and Allied Aquacultures. Auburn University, Alabama 36849 USA, 37 pp.
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Alabama Agricultural. Experiment Station, Auburn University.
7. Ding Nggc Thanh, H6 Thanh Hai, Duong Due Tien vi Mai Dinh Yen, 2002. Thiiy sinh hpc cic thuy vyc nude ngpt npi dia Viet Nam. H i Npi: NXB Khoa hoc vi Ky thuat.
8. Dang Van Ty, Nguyen Hoang Huy, Chau Thi Da, Vu Ngpc Ut va Tran Vin Viet, 2018. Dinh gia sy bien dpng nuoc tai Bung Bmh Thien, tinh An Giang.
Tap chi Khoa hoc - Truong Dai hpc Can Tho. Tap 54, S63B (2018): 125-131.
9. Le Himg Anh, 2008. De xuit cac chi tiii sinh hoc cu tiie cho loai binh he sinh thii tiniy vuc nude chay cua Viet Nam; phin tich, danh gia tinh kha tfii vi tinh sin cd cua du lieu. Hi Noi: Tong cue Mdi truong, Trung tim Quan trie Moi truong.
10. Le Van Cit, D6 Thi Hong Nhung vi Ngo Ngpc Cit, 2006. Nuoc nuoi tiiuy san chat lupng va giai phap cai thien chat lupng. Nhi xuat bin Khoa hgc v i Ky thuat, H i Npi, 424 trang.
11. Pham Manh Toan, 2012. Thinh phan phieu sinh vat trong cic sinh canh o tinh Sdc Tring. Luan van cao hgc. Tnrdng Dai hgc Cin Tho. Thinh pho Can Tho.
12. Pham Qudc Nguyen, Le Hong Y, Nguyen Van Cdng v i Truong Qudc Phu, 2014. Dien bien mot sd chi tieu chat lupng nude trong ao nuoi ci tra (Pangaslanodon hypophthalmu^ tham canh. T^p chi Khoa hoc - Trudng Dai hoc Can Tho. Thanh phd Can Tho.
14. Pham Van Thuong v i Dang Dinh Bach, 1999.
Giio trinh co so hoa hpc mdi trudng, Nhi xuat ban Khoa hoc va Ky thuat Ha Ngi, 231 trang.
15. So Tii nguyen va Mdi truong tinh An Giang, 2018. Bao cao ket qua quan trie moi trudng tinh An Giang - dot thing 3 nam 2018,136 trang.
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17. Tdng cue Moi trudng, 2011. Quyet dinh sd 879 /QD-TCMT, ngiy 01/07/2011 ve viec "Ban hinh sd tay huong din tinh toan chi sd chat lugng nuoc".
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NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 9/2020
KHOA HOC CONG NGHE
PHVTOPLANKTON-SURFACE WATER QUALITY RELATIONSHIP AT BAC VAM NAO, AN GIANG Nguyen Thanh Giao^
^College of Environment and Natural Resources, Can Tha University Email [email protected] Summary
This study was conducted to examine the relationship between phyLoplankton composition and water quality in Bac Vam Nao flood control area. An Giang. Three phytoplankton samples (VNl, VN3 and VN5) were collected in march and September 2018. Water samples (VNl, VN2, VN3, VN4 and VN5) were also collected in march and September from 2015 to 2018 to assess water quality and examme the relationship between phytoplankton and water quality at the sampluig sites VNl, VN3 and VN5. The findings revealed that the water quality in the study area was polluted by organic matters due to low of DO and high of TSS, COD, BODS comparmg to surface national technical regulation on surface water (QCVN 08-MT:
2015/BTNMT, column Al). In addition, water environment was also contaminated by coliform. For phytoplankton, Eugienophyta, Chlorophyta, Cyanophyta were the major phyla accountmg for 23.9%, 22.8%, and 22.8%, respectively. These phyla indicate water environment was polluted by organic matters which was in accordance with the results of chemical and physical water quality parameters analysis. Shannon Weiner diversity index (H") at the observed sites ranged from 0.569 to 2.580 indicated seasonal vanation of water quabty from light pollution On wet season) to severe pollution On dry season). At the same sampling sites, the water quabty mdex (WQI) ranged from 4 to 37 mdicating water quality from moderate to severe pollution, which did not show the seasonal fluctuations of water quality as H'. Tlie present study pointed out that H' and WQI did not show the same status of water quality since phytoplankton be also affected by weather and phytoplankton predators. Therefore, water quality momtoring should be conducted on the basis of combining physical, chemical charactenstics and phytoplankton composition.
Keywords: Bac Vam Nao, organic pollution, phytoplankton, Shannon-Weiner diversity index (H), water Quahty index (WQI), water quality.
Ngudi phan bien: PGS.TS. Nguyen Xuin Ljr Ngiy nhin bii: 28/11/2019
Ngiy thong qua phan hiem 30/12/2019 Ngiy duyet ding: 6/01/2020
