Mahmood Hossain*
Forestry and Wood Technology Discipline, Khulna University, Khulna 9208, Bangladesh
Heavy metal; Micronutrient; Organic waste; Pollution; Zinc
Sepang mangrove reserve forest in Selangor, Malaysia
Crop-Soil-Water Management
Fertilizer, Mangrove
Site Description: This study was conducted at the Sepang mangrove reserve forest in Selangor, Malaysia. Sepang mangrove reserve is situated on both the sides of the Sepang Besar river which is the stat e boundary of Selangor and Negri Semblilan. This mangrove forest is located in between latitudes 20 36' - 20 41' N and longitudes 1010 42' - 1010 46' E. A limited number of plant species is found of which Rhizophora mucronata, Rhizophora apiculata, Avicennia alba, Sonneratia alba, Bruguiera gymnorrhiz, Ceriops tagal and Xylocarpus granatum are most available. Of these species, Rhizophora mucronata has a wide distribution and the highest density (350 trees per ha).
Sampling Procedure: Six stations, each every 2 km from waste discharge points of pig farms towards the sea, were chosen. Two plots (each of 3 m X 3 m) were taken from each station and each was divided into three sub plots of 3 m X 1 m size. Total and available soil zinc and zinc concentration in infiltration water were measured for each station. Rhizophora mucronata seedlings were not found at Station 1, 2 and 3 hence zinc concentration was also measured in river water adjacent to each station. Zinc concentration in leaves, stems and roots of Rhizophora mucronata seedlings were measured in the last three stations toward the sea.
Soil analysis: Topsoil was collected by digging a hole of 10 X 10 X 10 cm sized in 3 sub plots of each main plot. One soil sample was taken from each sub plot. Samples were air-dried at room temperature and thoroughly mixed before crushing and sieving. Total soil zinc was extracted by using concentrated HNO3 and 60% HClO4 in the proportion 2:1 (Hesse 1971) and 0.1M HCl was used for determining the available soil zinc.
Water Analysis: After taking a soil sample, accumulation of infiltration water can usually be observed at the bottom of the hole. Once the column reached equilibrium, the water in the hole was rapidly displaced with suction bulb and transferred to the bottle. Infiltration water samples were collected from all sub plots of all stations. River surface water was collected at mid width of the river adjacent to the plots of each station. Two river water samples were collected from each station. Total (dissolved and suspended) substances of river and infiltration water were brought into solution by using concentrated H2SO4, 60% HClO4 and HNO3 in the proportions 1:2:10 (Allen, 1974).
Plant Analysis: Three seedlings of Rhizophora mucronata having 4 leaves were collected from sub plots of Stations 4, 5 and 6. Samples were separated into different parts (i.e. leaves, stems and roots) and then oven-dried at 800C. The dried material was then ground and sieved. Concentrated HNO3 and 60% HClO4 in the proportions 1:1 were used for plant sample ext raction. Atomic Absorption Spectrophotometer (AAS) PERKIN ELMER 4100, Germany was used for measuring zinc ion concentration in the extract.
Soil and Water Parameters other than Zinc: Texture of soil samples was measured with the pipette method. Fresh moisture content was measured by weight loss method and cation exchange capacity of soil was measured by distillation and titration method. Soil organic matter content was determined by the ignition method where oven dried (at 1050C) soil sample was ignited at 4500C for burning out the organic matter. A pH meter with an automatic temperature compensator (CibaCorning Diagnostic Ltd. France) with accuracy of ± 0.05 was used to measure soil pH in situ from slurries of the samples in water (Peech, 1964). The pH of river water samples was measured in the field by following the same principle as described for soil samples. A conductivity and TDS cell (Ciba-Corning Diagnostic Ltd. France) were used for determining the conductivity and the total dissolved solid of river water in the field. River water salinity was measured directly in the field using a salinity meter (YSI model 33 manufactured by Yellow Springs Instrument Co. USA). Dissolved oxygen (mg/l) was measured by HI 9142 oxygen meter (HANNA Instrument, USA).
Khulna University Studies, 2(1): 149-157
Journal