SEASONAL VARIATION OF GRAIN SIZE AND HEAVY METALS CONCENTRATION IN SEDIMENT OF SUNGAI PERLIS

Abstract Heavy metals concentration (As, Co, Cu, Pb, Zn, Cr) and grain size analysis were determined in sediment collected from Sungai Perlis during Southwest and Northeast monsoon. Ten sampling areas of the Sungai Perlis were selected based upon anthropogenic activities which resulted in elevated metals load into the river. Heavy metals concentration in the sediments show average decreasing trend of Zn>Cr>Pb>Cu>As>Co during Southwest monsoon and Cr>Zn>Pb>As>Cu>Co on Northeast monsoon which can be related by the impact of the anthropogenic activities. Most of the sampling areas were dominated by silt sediments while sand and clay sediment were poorly present. Result of grain size showed that the average mean size, sorting and skewness are 7.32 ± 0.44 phi, 1.55 ± 0.14 phi and -0.16 ± 0.19 phi for Southwest monsoon and 7.14 ± 0.27 phi, 1.56 ± 0.12 phi and -0.08 ± 0.17 phi during Northeast monsoon. The analysis of heavy metals and grain size fractions of sediments indicated that the distributions of metals and grain size in upstream and downstream river sediments were affected by monsoon seasons. Keywords: grain size, metals, sediment, Sungai Perlis, seasonal variation Abstrak Kepekatan logam berat (As, Co, Cu, Pb, Zn, Cr) dan saiz zarah telah ditentukan di dalam sedimen yang diperolehi daripada kuala Sungai Perlis ketika musim monsun barat daya dan timur laut. Sepuluh kawasan telah ditentukan di kuala Sungai Perlis berdasarkan aktiviti manusia yang akan menyumbang kepada kepekatan logam berat di dalam sungai. Kepekatan logam berat di dalam sungai menunjukkan gaya penurunan Zn>Cr>Pb>Cu>As>Co ketika musim monsun barat daya dan Cr>Zn>Pb>As>Cu>Co ketika musim monsun timur laut di mana ia mungkin dipengaruhi oleh aktiviti manusia. Kebanyakan kawasan sampel diambil menunjukkan dominasi lumpur yang halus tetapi pasir jarang sekali dijumpai. Keputusan saiz zarah menunjukkan purata nilai min, susunan dan skewness adalah 7.32 ± 0.44 pai, 1.55 ± 0.14 pai dan -0.16 ± 0.19 pai untuk monsun barat daya dan 7.14 ± 0.27 pai, 1.56 ± 0.12 pai dan -0.08 ± 0.17 pai ketika musim monsun timur laut. Keputusan analisis logam berat dan saiz zarah di dalam sedimen menunjukkan taburan logam dan saiz zarah di muara sungai adalah dipengaruhi oleh musim monsun. Kata kunci: saiz zarah, logam berat, sedimen, Sungai Perlis, variasi musim Introduction The increasing growth of human population has lead to the land development alongside of the river basin. Most of the rivers which were affected by the industrialization and urbanization become the end point where all of the effluents are discharge directly from the factories and municipal waste. This phenomenon gives stress to aquatic ecosystem which soon giving rise to water pollution and environmental deterioration. Pollutant such as heavy metals usually being carried by the runoff from the primary sources and spread to other part of the aquatic ecosyste