Monsoon effects on Variation of heavy metals in Gwatr mangrove forests of Iran

ABSTRACT: We conducted an investigation of heavy metals concentrations in Gulf of Gwatr during monsoon phenomenon. To estimate levels of the heavy metals in sediment and leaves of Avicenia marina in this area, the samples were collected periods of premonsoon, monsoon and post-monsoon (May, August and November 2010 covering three seasons). After preparation of samples the concentration of Cd, Ni, Cu and Zn were measured by the Konic model NOVAA 300 atomic absorption spectrophotometer. According to the results the high concentration of Ni, Cu and Zn in monsoon and post monsoon in compared to the premonsoon could be due to the monsoon effect and increase of Bahukallat river runoff from upstream. But the concentration of Cd is low in this area and seasonal variation could not be affected on this metal concentration in this area. The heavy metals concentrations in sediments in three seasons were consistent and ranked in decreasing order of Ni > Zn > Cu > Cd, while concentrations in leaves were ranked as Zn > Cu > Ni > Cd respectively. Only Bioconcentration factors of Cdhad obviously occurred in leaves of A. marina in three seasons. That indicating the leaves of A. marina can accumulate Cd to the same degree as the sediments. The concentration of Cd, Cu and Zn in sediment samples was thought to be of natural origin from the soil.