Kriging-GIS model for the spatial distribution of seawater heavy metals

Abstract

Development in the seawater region of Bungus Bay - Padang City continues to develop rapidly, this can cause damage to the surrounding water environment due to seawater pollution and high sedimentation. Therefore, research is needed on the analysis of seawater’s heavy metal contents and the spatial distribution of contamination values based on the Decree of the Minister of Environment (KEPMEN LH) No. 51/2004. This study aims at elaborating the correlation between the distribution of heavy metals (Cd, Cr+6, Pb, and Cu) in the seawater region of Bungus Bay. The data processed is data on heavy metal content from the results of sample measurements using the AAS, where the points and values of the sample analysis that have been collected using GPS at 3 location points are then imported into GIS using GIS Kriging. The value of heavy metal index for seawater based on the quality standard of KEPMEN LH No/5/2004 shows that a category does not fit, where Cd (0.0013-0.0031 mg/l), Cr+6 (0.008-0.013 mg/l), Pb (0,009-0,017 mg/l), and Cu (0.010-0.014 mg/l). The value of concentrations of these heavy metals generally shows a spatial distribution pattern different in each direction of movement. On one hand, the highest concentrations of this heavy metal are generally located in the Northwest of the bay (Cd, Cr+6, Pb) except Cu which is in the Northern part of the bay, as it is close to the discharge locations and outlet of rainwater from the catchment area. Generally, heavy metal contamination in the seawater region of Bungus Bay comes from the household, industrial, and ship loading and unloading waste. The pollution occurs as the result of the oil from transferring tankers, oil spills from fishing boats that rinse at Bungus PPS, and debris resulted from the plywood industry activity.