Nghiên cứu và dánh giá hàm lượng một số kim loại nặng trong trầm tích đáy vùng cửa sông mê kông

TAP CHi KHOA HOC OHSP TPHCM Phung Thdi Duffng vd tgk NGHIEN c t r u VA DANH GIA HAM LlTONG MQT SO KIM LOAI NANG TRONG TRAM TICH P A Y VUNG CU'A SONG ME KONG PHUNG THAI DUONG*, HU^NH THj Kl£U T R A M " Di tdi dugc thuc hiin nhdm xdc dinh hdm lugng kim logi ngng trdm tich day viing cua sdng Me Kdng Ngoai trie Pb thi hdm lugng cdc kim logi Igi tai hdu hit cdc diim nghien cicu gdn bdng quy chudn qudc gia Viet Nam (diing di ddnh gid mice dd dnh hu&ng bdt Igi den cdc ddng vdt thuy sinh vd hi sinh thdi ven sdng) So v&i quy chudn cua mot sd nu&c tren the gi&i thi hdm lugng kim logi ngng tgi khu v^cc nghiin ciru a mire cao Cdc nhdnh sdng nhd vdo sdng chinh ciing cd hdm lugng tuang ddi cao diiu ndy chicng td ben canh ngudn gdy d nhiim tic phia thuong ngudn thi hogt dgng kinh ti - xd hdi cua nguai ddn nai ddy eUng cd vai trd to l&n ddi v&i viic tich tu cdc kim loai ndng trdm tich day sdng Tu khda: ham lugng kim loai nang, tram tich day, cua sdng Me Kong ABSTRACT Research and evaluate contents of heavy metal in river sediment in the estuary of the Mekong river The study was carried out to determine the content of heavy metals in the estuary of the Mekong river Except for Pb, the contents of other metals at most research points are close to the standards prescribed by Vietnam (used to assess the level of adverse effects to the aquatic and riparian ecosystems) Compared with the regulations of some countries in the world, heavy metal content at research point is al high level In small tributaries that flow into the main river, the content is also relatively high This proves that besides polluting sources from the upstream, economic - socio activities of the local people also play an important role in the accumulation of heavy metals in the river sediments Keywords: the content of heavy metals, sediments, estuaries of the Mekong river I Md dau Sdng Me Kdng dai khoang 4880 km, vdi luu lugng la 475 trieu mVnam Bat ngudn tir Trung Qudc, chay qua Lao, Myanmar, Thai Lan, Campuchia va Bien Ddng Tai Viet Nam song Me Kong dugc ggi la sdng Ciiu Long Song Cim Long chay hai nhanh song song: song Tiln va song Hau, dai khoang 230 km tir bien gidi Viet Nam - Campuchia den Bien Ddng Trudc dd biln song tao ddng bing chau thd rdng Idn vdi ciia: sdng Hau; cira (hien mpt cira da bi bli lip), sdng Tiln: ciia (trong dd cd Ham Ludng) [13] ' TS, Trudng Dgi hpc D6ng ThSp; Email: phungthaiduongdhdt@gmail " GV, Trirdng €)ai hpc Dong Th^p com 119 TAP CHi KHOA HOC OHSP TPHCM s6 9(75) ndm 2015 \'img cira sdng, ven Men thudi^ la noi tich tu cac chit d nhilm, kim loai nang c6 ngudn gdc tir ndi dia \'di dien tich luu vyc rdng Idn 795.000km^ [12], sdng Me Kong chay qua nhieu viing ndng nghiep cong nghiep va dan cu; dd hang nam lugng kim loai nang dugc ddng nudc mang tir phia thugng ngudn va tich tu tram tich day tai viing cua sdng la tucmg ddi cao, kha nang xam nhiem vao he sinh thai la rat Idn NTian thurc dugc nhimg hiem hga ma kim loai nang mang lai ddi vdi ngudi dan luu vuc nhilu cdng trinh nghien ciiu dugc lien hanh cd the ke den: T.P Murphy (2008), Xiang Huang (2010), A Sakultanlimelha (2010), Gassert.F (2012) Nghien ciiu trim tich tai Viet Nam cd the ke den: Ngm en Van Tho (2007), Doan Thj Thanh Thuy (2007) Pham Viet NO (2011) Le Thi V u i (2012) Pham Thi Nga (2012) [2] Nhin chimg nghien cihi phan kim loai nang tdn tai nudc, trim tich dugc cac nha khoa bgc va ngoai nudc bat diu quan tam, nhien cdng trinh nghien cihi trim tich day sdng Me Kdng cdn it, chi thyc hien mdt vai chi tieu va linh hinh hien dii lieu da cu Dong bing sdng Cuu Long vdi hau nhiet ddi gid miia, lugng mua hang nam cao, ciing vdi dd la su cudn trdi ting dit mat; de khac phuc hien tugng dd, ngudi dan noi da> thudng sir dung trim tich ^ y de bdi dip tryc tiep vao gdc cac vudn cay an trai Viec lam trudc mang lai hieu qua, nang suit ca> trdng cao nhung gan day da xa> linh trang mgt sd vudn ca\ nhan, ca cao, budi la nga vang, chet hang loat Hien tugng dugc li giai la ngudi dan da sir dung trim tich day d nhiem kim lorn nang bdn tryc tiep vao cay trdng, cac loai ca> chi cd kha nang chdng chiu vdi ham lugng kim loai nang rat thap Do dd, viec nghien ciiu ham lugng kim loai nang tdn tai mdi trudng dac biet la trim tich day sdng noi da>" la het siic can thiet Vdi viec nghien cuu tdng sd cua cua sdng Me Kdng, bai bao se lap trung phan tich ham lugng kim loai nang trim tich day ciia vimg nghien ciiu Ngoai ra, tac gia cdn lien hanh so sanh vdi chuan quy dinh ciia Viet Nam va mgt so nudc tren the gidi lam co sd cho viec dinh hudng sii hgp li ndng nghiep va phat trien ben \\mg Phinmg phap n^ien cuu Zl Vl tn, thcri gian vd so luang mdu Vi tri lay mau: vung cua sdng Me Kdng, bao gdm: ciia Ham Ludng, Cua Dai, Cua Co Chien va cac sdng nhanh cua sdng Ham Ludng (ggi chung la vimg ciia song Me Kdng) (hinh I) Thdi gian va so lugng mau: nam 2013 (20 mlu), nam 2014 (3 mau tai cac vi tri 1, 7,11), dugc bd tri nhu hinh L TAP CHi KHOA HOC DHSP TPHCM Phung Thdi Duang vd tgk Hinh Vi tri cdc diem lay mdu trdm tich day vimg cira sdng Me Kdng Chung toi bd iri cac diem lay mau tren cac nhanh song chinh, thudng tranh khu vyc dau cu lao, nhimg noi ddng nudc chay xiet se anh hudng din chit lugng miu; phan ho cac diem lay mau tuong ddi deu nhau, tir xem xet sy thay doi ham lugng cua cac nguyen td tir phia thugng nguon hudng ve phia ciia song Ddi vdi cac diem tren cac song nhd chay vao Ham Ludng, chung tdi bd trf tai cac nhanh sdng chay tir cac vung nong nghiep, cong nghiep quan trgng tren dia ban, de xem xet miic dp dong gdp ciia chiing ddi vdi d nhiem kim loai nang tram tich day tai viing nghien ciiu 2.2 Phuang phdp lay mau - bdo quan mdu Phirong phap lay mau Dung cu Idy mdu Dung cu liy miu dugc thilt ke tir cac vat lieu: Ong nhya dai khoang 50cm, nip day dng nhya, mieng cao su, dc vit dimg de tao van tu ddng, cay dai khoang 12m, day cot vao diu sao, day deo dimg quan thiet bi lay mau vao cay sao, cay gd khoang 70cm dl diii miu (dugc tac gia tham khao va thilt kl theo dung cu liy mlu trim tich day song dugc sir dung tai Bd mdn Dia sinh thai - Dia chit cdng trinh, Khoa Tai nguyen thien nhien, Trudng Dai hgc Bach khoa Tomsk, Lien Bang Nga) Phuang phdp Idy mdu Sau da xac dinh tren ban dd dia dilm liy mau, tdi hien trudng, lay each mep bd khoang 15 - 25m vi nlu liy gin bd bj anh hudng bdi xac thyc vat, la cay, tac dung cua anh sang mat trdi trilu xudng Liy xa bd thudng dong chay qua manh, phin liy len chu ygu la cat, khdng theo yeu ciu ban dau la biin Miu dugc liy tir bl mat xudng sau khoang 20cm [9] Mdi dia dilm xac dinh liy miu, ta tiln hanh liy miu Idn (mdi miu Idn bao gdm ba miu nhd liy each 5m, trdn vao mgt miu dai dien) Miu Idn each 20m xung quanh vj tri liy diu tien cua dilm Liy mlu theo quy tic tam giac can (hinh 2) Mlu dai dien dugc liy sau da Iron tii ba mau Idn 121 TAP CHi KHOA HOC DHSP TPHCM sa 9(75) ndm 2015 ' •/ / \ \ ^ / —\ ^ -\ 1-143M / ' \ *• IRnh Z Sa dd mo td dia diim Idy mdu Trong dd: la, lb, 3b, 3c: mau nhd; ,2, 3: mau Idn (bao gdm mau nhd); I, II, III: mau dai dien cho diem lay mau (bao gdm mau Idn) Phuong phap bao quan mau Mau dai dien dugc bao quan tiii nilong, tranh tiep xuc vdi anh sang Ben ngoai tiii sii dung giay dan khdng tham nudc, ben de ki hieu, ghi day dii cac chi tiet ve dia diem, vj tri lay mlu each bd bao nhieu met, gid thu mau, sau noi lay mau Mau dugc phoi khd tu nhien d noi sach se, kin gid vdi nhiet phdng (khoang 25*'C) [10] Khi kho, dugc nghien va sang qua ray cd mat ludi 0,5mm [10] Phuong phap pha mau vi song Cac kim loai nang ton tai mau tram tich day d dang vd co va huu co Muon dugc tren may hap thu nguyen tu chung ta can chuyen cac mau ve dang vd co (dung dich) De thyc hien cong viec nay, chiing toi su dung thiet bi pha mau vi song (Model: MW 680 _ San xuat: Aurora - Canada) vdi sach hudng dan, cac cdng doan thyc hien ciing vdi chuong trinh TRANSFORM680 kem theo may Phuong phap phan tich cac chi tieu Cac chi lieu kim loai nang dugc phan tich bang may quang phd hap thu nguyen tir (Model: ZEEnit 700_San xuit: Analylik-Jena - Diic) cimg vdi sach hudng dan va chuong trinh WinAAS Ver kem theo may Cac chi lieu cdn lai dugc phan tich theo Savichev O.G, 2012 [10] Muc phat hien thip nhit cua phuong phap khoang 0,2^g (trung binh cho tat ca cac chi tieu do) Cdng viec ihuc dia dugc sy tham gia cua cac ddng nghiep Trudng Dai hgc Dong Thap va Dai hgc Cin Tho Cdng viec thi nghiem, phan tich dugc tien hanh tai Trudng Dai hgc An Giang (nam 2013) va Dai hpc Bach khoa Tomsk, phd Tomsk, Lien Bang Nga (nam 2014) 122 TAP CHi KHOA HOC OHSP TPHCM Phung Thdi Duang vd tgk Ket qua nghien cihi va thao luan Ham lugng trung binh kim loai nang tram tich day cua 20 dilm liy mlu dugc thuc hien n5m 2013 tai vimg cua sdng Me Kdng dugc thi hien theo thii tu lir thip din cao: Hg>Cd>Pb>As>Cu>Zn (hinh 3) Hinh Hdm luang trung binh cua kim logi ndng viing cira sdng Me Kong [mg/kg trgng hcang trdm tich kho] Khai thac quang md, luyen kim, biin thai cong ranh, bui than [3] la mpt nhihig nguyen nhan dan den lam lugng Zn gia tang tai viing cira song Me Kong Dgc luu vyc sdng Me Kong vdi nhiing vimg nong nghiep trii phu (Thai Lan, Viet Nam la hai nudc cd san lugng liia gao nhat nhi the gidi, dong bang song Ciiu Long dugc menh danh la "vuong quoc trai cay" ), cung vdi dd la viec sir dung phan bdn, thudc trir sau eang nhieu, day la mgt nhan td chinh gop phan dan tdi ham lugng Zn tram tich cao nhit Nen dia chat lim vuc sdng Me Kong dac tnmg vdi da cd ngudn goc nham thach (cao nguyen Khorat, cao nguyen Kon Tum ) loai da vdi ham lugng Cu tucmg ddi cao Luu vyc song Me Kdng cd lugng mua Idn, am cao, qua trinh phong hoa dien manh me dan din lugng Cu theo dong nudc va tich tu tram tich day tai vimg ciia sdng Ben c£inh cac boat dpng san xuat cua ngudi dan luu vyc da gop phan lam cho Cu co ham lugng tich tu dung hang thii hai tram tich day tai viing nghien ciiu As tram tich day cd nguon gdc ty nhien (cac khoang chua asen) hoac ngudn nhan t^o (luyen kim, khai khoang) As cd nhilu xdi mon va hoat dgng khai thac cac vimg da giau As nam dgc bien gidi Viet Nam va Campuchia Hg cd nhieu cac boat ddng cua nui lira xua Ciing vdi dd la qua trinh san xuit cdng nghiep, khai thac mo, luyen kim 123 TAP CHI KHOA HOC DHSP TPHCM Sd 9(75) nam 2015 Trong ty nhien, Cd cd nhieu cac da cd nguin gdc nui lira phan bo phia thugng ngudn Me Kdng Pb la nguyen to tao hgp chit luu huynh, cd nhilu da mac ma Ben canh Cd, Pb cdn dugc phat hien vdi ham lugng cao cac da tram tich va bien chat tai viing Bac Lao [2] Hien d ddng bang sdng COai Long, cac khu cdng nghiep ciing tuong ddi phat trien, lang nghe, nha may phan bd dpc hai ben bd sdng: thudc nhugm, son men gdm, tranh son mai, san xuat xi mang Cac thi mpc len, cung vdi cac nha may xir li nudc thai va viec sir dung phan bdn, thudc hda hpc cho cac loai cay trdng, vat nudi la nhung nguyen nhan quan trpng gdp phan lam cho ham lugng Cd, Pb tai vimg nghien cim cao va vupt miic so vdi chuan quy dinh ciia Viet Nam Bdng Hdm lugng mdt sd chi tieu kim logi ngng trdm tich day tgi cdc diim Idy mdu tgi viing cira sdng Me Kdng [mg/kg trgng lugng trdm tkh khd] ^ ^ " \ C h I tilu 124 Zn Cu Pb Cd As Hg 96,1 31,3 0,9 0,1 4,7 80,7 30,3 2,2 1,0 3,9 0,11 75,1 28,4 1,3 0,2 4,2 0,07 123,0 33,8 6.1 2,4 6,2 0,06 101,2 34,8 2,3 1,2 6,4 0,09 77,6 34,4 4,9 1,4 5,9 0,09 92,1 34,9 4,4 0,9 7,6 0.12 91,3 34,9 3,0 1,0 6,6 0,12 91,2 35,7 4,6 1,5 7,5 0.13 10 106,4 35,2 4,9 1,0 7,7 0,13 11 97,2 31,2 6.6 1,4 8,2 0,14 12 107,3 38,5 5,7 2,4 8,0 0,13 13 105,4 32.4 1,1 0,6 6.3 0,09 14 99,8 33,6 6,0 03 4,1 0,07 15 90,5 34.6 31 1.1 4,0 0,08 16 100,2 35.0 3,7 1.1 4,0 0,04 17 87,7 28.5 1,1 1.1 4,6 0,07 18 102,6 33,5 6,3 1,6 7,7 0,12 0.10 0,09 19 100,1 331 2,8 0,2 4.1 20 105,7 33,4 4,3 1.9 6,2 014 A 96,6 33,4 3,8 1.1 5,9 0,10 8» 2,5 0,5 0,4 0,1 0,4 0,01 TAP CHi KHOA HOC DHSP TPHCM Phung Thdi Duffng va tgk Theo ket qua phan tich 20 mlu tram tich day dugc thuc hien nam 2013 (bang 1), co 12 miu doc song Ham Luong, co the nhan thSy: Ham lugng kim loai nang cua hau het c^c chi tieu co xu huong tang diin theo hucmg v8 phia bien DiSu chimg to eang vi phia luu, vimg ciia song thi su tuong tac qua lai giOa song va bifa dien eang manh me, dan dSn su tich tu phii sa va kem theo la cac kim loai nang co ngu6n g6c tir noi dia Trong moi truang thuy sinh, trSm tich CO vai tro quan trong su hip thu cac chit gay nhiem sir ling dpng cua cac hat lo lirng va cac qua trinh co lien quan den hk mat cac vat chit v6 co va hiru co Rieng d6i voi cac mlu thu tai cac nhanh song nho chay vao song Ham Luong (mau 13-16) co ham lugng tuong d6i Ion hon song chinh Digu chimg to ben canh dirge mang tii phia thugng nguon, thi hoat dgng san xuit cua ngudi dan dia phuong ciing gop phan khong nho dSn vice tich tu va nhiem ham lugng kim loai nang tram tich day nai day Bdng Chi so pH vd EC ciia trdm tich day tai viing cira song Me Kong Diem lay mau Khoang each tir bien pH DO dan dien, EC (ms/cm) Ham Luong, 75 KM 6,59 309,0 Ham Luong, 70 KM 6,87 1106,5 2865,0 Ham Luong, 64,5 KM 7,44 Ham Luong, 57,2 KM 7,04 921,5 Ham Luong, 44,5 KM 7,23 2215,0 Ham Luong, 41,6 KM 7.34 4305,0 Ham Luong, 35 KM 7,57 4355,0 Ham Luong, 28 KM 7,63 4347,0 Ham Luong, 20,5 KM 7,62 4699,5 10 Ham Luong, 15,2 KM 7,80 4956,0 11 Ham Luong, 9,2 KM 7,88 4940,0 12 Ham Luong, 4,2 KM 7,98 5573,0 13 Nhdnh sdng Hdm Luong: Sdng Ben Tre 44 KM 6,25 357,0 14 Nhdnh song Hdm Luong: Song BaTrl 10,6 tcM 7,17 4330,0 15 Nhdnh song Hdm Luong: Song Vdm Nudc Trong, 49,4 KM 6,66 6905 16 Nhdnh song Hdm Luong- Song RachSdu, 16 KM 7,09 3290,0 So 9(75) nam 2015 TAP CHI KHOA HOC BHSP TPHCM Diem lay mau Khoang each tir bien 17 Co Chien 685 KM Co Chien 5,5 KM 18 19 20 pH 6,77 Do din dien, EC (ms/cm) 484,5 8,08 6,37 7,93 5447,5 A 7,26 3042,9 8A 0,12 444,1 Cira Dal, 59,4 KM Cda Dai t:M 572,5 5092,5 Ghi chu' A, 8A - Chi so trung binh va sai so ( ^^ -al 4N , O - Dp lech chuan; A' - tong lugng mau) pH thap cd tinh axit, pH cao cd tinh kiem Sy hda tan cua mpt so anion S04^", NO3" va cac hgp chat kiem eang tang gan bien cac hoat dgng sinh hoat san xual ciia ngudi dan viing luu Ben canh pH ciing ti le thuan vdi dan dien EC va dp cua sy trdn lan nudc bien (nudc ngpl vdi dp axit cao hon) Qua ket qua phan tich chiing ta thay rang pH cd gia tri tang dan tien ve phia bien, tuong ty nhu ham lugng cac kim loai nang (bang va hinh 4) [2] Chi sd thay ddi dieu kien thuy hoa d ddng bang la pH, cac gia tri cd the dugc su dung cho mot udc tinh gan diing cua cac dy bao thuc le va cac nguyen to vi lugng tram tich dgc theo chieu dai cua song Me Kdng nam ciing nhu viec lap ke hoach hoat dgng ndng nghiep, quan li nudc va dam bao cho viec phat trien ben virng tai vimg ddng bang 6,5 6,0 O 20 40 60 K h o i m g cAck O ^ b i ^ k m 80 Hinh Su thay ddi ndng pH trdm tich doc song Hdm Luong (ndm 2013, y = -0,016lx+8,0402; R' = 0.8529) 126 TAP CHi KHOA HQC DHSP TPHCM Phung Thdi Duang vd tgk pH la mdt chi sd quan trgng cua cac tuong tac he thdng tdng hgp "mdi trudng" [12] Dac biet, sy gia tang pH lam tang mire d6 bao hoa cua nudc trim lich vdi cac hgp ch§t kim loai tuong ddi it tan: axit humic, cacbonat va khoang chit d4t set (bang 3) Ket qua viec loai bd ciia mpt sd chat, diln ddng thdi vdi viec ket liia va hap phu tren cac hat bun dat va tram tich Bdng Hdm lugng trung binh mgt sd ion vd kim logi ndng trim trich ddy vi4ng cira sdng Me Kdng (ndm 2013 vd 2014) so v&i chudn quy dinh tgi Viet Nam vd mdt s qudc gia tren thi gi&i Viing cira song Me Kong, niim 2013, iV=20 Song chinh Ham Luong, i dA I s Quy chuan ctia Hoa Ki [111 pH 7,26 0,12 7,43 0,17 - Dp dan die- EC (ms/cm) 3042,9 444,1 1280,2 951,1 - - - 102,3 12,4 96.0 41,2 761,8 675,9 58,0 35,7 - ^ - _ - Chi tieu nam 2014, JV=3 Quy ehuan eiia Canada [4] Quy chuan Viet Nam [1] - - mg/kg (trgng lugng tram tich kho) SO4'" _ - - NO3" 31,6 2.1 NH,* 47,3 Ca^* Mg'* Na* K* 30,3 ^ ^ - - 1,8 110,0 123,0 271 0,3 16,0 35,7 108 31,0 35,0 112 207,3 42,8 1024,6 980,2 584,8 193,7 4,2 2,1 2,9 3,1 118,7 1,1 9,9 ^ - 32403,3 1872,5 38393,3 6226,6 Mn - 713,9 Zn 96,6 2,5 84,0 Cu 33,4 17,5 Pb 3,8 0,5 0,4 22,7 1,3 HCO3" cr Si Fe Al 127 TAP CHI KHOA HOC BHSP TPHCM Chi tieu Vung cira song Me Kong, nam 2013, A'=20 Sd 9(75) nam 2015 Song chinh Ham Luong, nam 2014, A'=3 SA A SA Cd 1.1 5,9 0,1 0,4