Study of Metals Flocculation during Estuarine Mixing in South of Iran
Subject Areas : River Basin EnvironmentAyda Baiati 1 , Abdorreza Karbasi 2
1 - استادیار گروه تخصصی مهندسی منابع طبیعی- محیط زیست، دانشکده محیط زیست و انرژی، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات
تهران
2 - استادیار دانشکده محیط زیست دانشگاه تهران
Keywords: estuary, Flocculation, Heavy Metals, Dissolved Organic Carbon,
Abstract :
Estuaries are considered as important zones for the occurrence of environmental، biological and geochemical processes. Elements are carried to the sea through rivers and estuaries are pathways for this transmission. In estuaries dissolved elements of river water ooze out of dissolved phase due to several estuarine processes such as flocculation. In the present investigation، for the first time of flocculation Zn، Cu، Pb، Ni and Mn during mixing of a filtered sample (0.45µm) from Persian Gulf water with a filtered water sample taken from the Minab river in 9 different salinity proportions is studied. For the first time flocculation of elements in relation to redox potential (Eh) is investigated and the results indicated that elemental flocculation during estuarine mixing is not controlled by (Eh). The flocculation trend of studied metals is Cu (83.3%)> Ni (82.9)> Zn (75.2%)> Mn (69.4%) > Pb (38%). Flocculation rate varies considerably from one metal to another. Highest flocculation of metals occurs between salinities of 3.3‰ to 11.4‰. Statistical analysis indicate that flocculation of metals (except for Pb) is governed by dissolved organic carbon whose source is teri-genous in the area of study. The amount of metal flocculation is about 30.5، 6.6، 25.3، 10.4 and 36.5 ton/yr for Zn، Pb، Ni، Cu and Mn، respectively، as a result of mixing of Minab river water with the Persian Gulf water. Therefore estuarine processes can be considered as effective mechanisms in clean up of colloidal metals that are anthrop pogenically entered into the fresh water ecosystem.