Distribution of nitrate (NO3−) and posphate (PO43-) in water, sediment and seaweed of Morowali distric marine waters

Abstract

Abstract The seaweed market opportunity is very promising, this condition is in line with the national plan which positions Indonesia as the largest seaweed producer in the world. Seaweed production in Central Sulawesi, especially in Morowali district, has continued to decline since 2012-2021. The aim of the research was to examine the distribution of nitrates and phosphates in sea water, sediment and seaweed at seaweed cultivation sites around mining sites in Morowali District which is suspected to be the cause of this situation. Observation stations include South Bungku Waters, Bahodopi Waters, Witaponda Waters and Bumi Raya Waters. The results showed different nitrate and phosphate contents in sea water, sediment and seaweed. The nitrate content in waters throughout Morowali district ranged from 0.071 to 0.202 ppm, and phosphate from 0.001 to 0.013 ppm. The nitrate content in the sediment was in the range of 2.67-8.15 ppm and phosphate was in the range of 0.001-3.03 ppm. Meanwhile, the nitrate and phosphate content in seaweed was from 20.36 to 40.68 ppm and 1.39 to 8.37 ppm respectively. The data showed that the highest nitrate and phosphate content was in seaweed tallus, followed by sediment and the lowest nitrate and phosphate content in sea water. This indicates that the nitrate content of seawater, sediment and seaweed has exceeded the tolerance threshold for seaweed growth. However, the phosphate content in seawater was still relatively low, while in sediment and seaweed tallus has exceeded the threshold.