FRAKSINASI UEOKIMIAWI LOGAM BERAT PADA SEDIMEN PERAIRAN PANTAI SEMARANG

Abstract

badmen herperan penning dalarn monitoring kualilas air disebabkan karenti sediemn %%anal nenampung bahan pencemar dan berpotensi membebaskan kontaminan ke kolom air dengan Inerubah kaolin fisika lammed tSalomints and Forstacr. 1984) Small mengenai kontammasi logam berat pada sedimen untuk memonaor pencemaran industri seringkali tergantun pada analisa kandungan logan herat total, rctapi informasi pada konsennasi total tidak cukup untuk mengetahut tingkah laku trace logans di Imgkungan karena hanya fraksi tertenlit said dad logain total yang yang tursedia untuk proses bicnogi dan diaganctik (Groot er.al.,1982; Martin el at, 1987; Tack and Verloo. 1995) . Uji koutaminasi logam herat di lingkungan perairan pantai yang berdasarkan kandungan logam total tidak dapat membedakan trace logam "lithogenic" yang kurang terscdia (not-available") bagi biota bat, iika dibandingban ..anthropogenic effects" dalam fraksi labil ("non-hlhogenie") yang "broavatlable" bagi biota. Stu% it meincelajari kontaminas: logam beral dalam sedimen yang dikoleksi dari perairan pantai Semarang dengan menggunakan prosedur ekstraksi bottahap (-sequential extraction"). Iltuuan stuch ini adalah untuk mengetahui kandungan total dan persentase trap Inaksi geolstmlawi ("exeltangeable","Easily Reducible Fractton". "Fe-Mn Fraction", ''Organically Bound Fraction", dan "Residual Fraction") dart logam berat Cu, Cd, Cr, Pb, dan Zn. Sembilan subsample sedum diambil Juni 2001. Sampel diambil dan 2 stasiun dan Sulam pelabuhan Lagting Mas dan satu dari lepara . Dalam 24 jam sampel dikdlingkan pada suhu 105 ° C dan disimpan dalam botol sampel yang sudah %nu% dengan larutan asam. Setelah itu sampel siap dianalisis kandungan total dan fraksi geokimiawinya. Basil penelitian menumukkan bahwa kandungan logam tertinggi Cu, Cr, Pb. dan Zn ditemukan di stasiun Dermaga (DNIG). Konsentrasi di kedua stamen Irtinnya Hatt f tinngi d:111 kesemuanya melebitu ambang bates untuk sedimen. kecuali %gam Cd yang masih di bewail ambang baths. Sedungkan garb tkaksi geokitniawi logarn-logam menunjukkan bahwa fraksi labil (F(-F3) dan fraksi organik (F4) mendominasi logam Cd di ketiga stasiun (PLB, DMG, dan JEP) musing-musing 80 °A. 78 %; dan 80 %, fraksi tersebnt juga mendominasi logarn Pb yaitu masiaBmasing 60 %; 83 %, dan 53 °A UnIuk logam Cu dan Zn di lokasi DNAG, fraksi Inbil mendominasi pub yaitu masing-masing 100 % dan 90 38 Adapun Mon Cr didortunasi oleh fraksi "Ighogenic". Berdasarkan basil fraksinasi yang tclah dilakukan terhhat bahwa adanya aktivitas tnanusia Eanthropogenic effects") ke lingkungan yang &Bridal uleh besamya fraksi Sediment plays a crucial role in water quality due to its role as a sink for pollutants and the potential later release of these contaminants to the water coloumn with changes in physicochemical conditions (Salomons and Forstner. 1984). Studies of the trace metal contamination of sediments to monitor industrial pollution often rely on lie analysis of total metal content, but information on total concentration is not sufficient For an understanding of the environmental behaviour of trace metals as only fraction of the total metal is bioavailable for biological ur diagenetic processes (Groot act, 1982, Martin ecat,1987, Tack and Vcrloo, 1995). Assesment of heavy metal contamination of the coastal environment based solely on total metal content also poses the difficult problems to regulators of distinguishing between background lithogenic trace metal which relatively unavailable to marine biota, versus anthropogenic increases in labile trace metals of greater availability to biota. This study examines heavy metal contamination in sediment collected from area of coastal waters of Semarang using a sequential extraction procedure, The purpose of the study was to know the content of total metals (Cu, Cd, Cr, Pb, and.Zn) concentration and to know the percentage of each fraction of those heavy monis in sediment which are "Exchangeable Fraction", "Easily Reducible fraction", "Fe-Mn Oxides", "Organically Hound Fraction", and 'Residual Fraction". A total of 3 sediment samples were collected in June 2001. 2 Samples were collected from Tanjung Mas Harbour (PLB), Port (DMG) and one from Jepar (,IEP) Within 24 hours collection, samples were dried at 105 C and stored in acid washed samples bottles. The result,' showed that the total trace metal concentrations were found hihgest at Poo station which for Cu : 106 ppm; Cr': 99,8 ppm; Pb . 74,2 ppm; Zn 236 ppm. The geochemical fractionation showed that labile fraction (FI-F3) and organ e fraction t Ihti dominate Cd in three station (PLB, DMG, JEP) which are 80 we, 78 and 80 %, respectively. These fraction also dominate Pb which are 60 %, 83 % and 53 % While for Cu and Zn at DMG station , labile fraction also dominant, which are 100% and 90 respectively. Cr was dominated by Orithogenic fraction" Based on fractionation resuts, it seems that there were anthropogenic factor (human activities) to the environment, marked by the big portion of labile fraction