Udayana University Researchers Test Soil Samples from Benoa Mangrove, Discover Contamination from Fuel-Like Compounds
A research team from Udayana University’s Agricultural Hospital has tested soil samples from mangrove forests in Benoa, Denpasar, Bali, and identified 41 hydrocarbon compounds or petroleum-derived substances, most of which are found in petroleum fuel products (BBM).
“We can conclude that the mangrove soil samples are positively contaminated by petroleum waste, especially diesel,” said Dr Dewa Gede Wiryangga Selangga, Coordinator of the Research Team, in Denpasar on Friday.
Testing was conducted on 24–26 February using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. This method is used to identify and determine the composition of chemical compounds in samples, particularly volatile or semi-volatile compounds.
From soil samples in the affected area on the western side of the Bali Mandara Toll Gate entrance in Benoa, 45 volatile compounds were found, with 41 of these being hydrocarbon compounds. The hydrocarbons detected in the samples are largely those found in fuel products such as petrol, kerosene, and diesel.
Compounds detected with percentages above five per cent include n-Hexadecane at 5.79 per cent, n-Heptadecane (7.65 per cent), Pentadecane, 2,6,10-trimethyl (7.27 per cent), Pentadecane, 2,6,10,14-trimethyl (8.67 per cent), and n-Eicosane (5.42 per cent).
The hydrocarbon compounds detected in the mangrove soil samples are dominated by hydrocarbons with a carbon atom range of C15–C24, which strongly indicates diesel (solar) contamination.
In water samples, only one compound from the organic hydrocarbon group was found, namely squalene, which is typically found in shark liver, certain algae, and microorganisms such as Escherichia coli.
“Therefore, no hydrocarbon contaminant compounds were found in the water samples tested,” the researcher added.
The researchers noted that hydrocarbon compounds were not found in water samples because cleaning operations had been conducted, causing oil contamination to migrate to the marine area.
However, the dominant hydrocarbon compounds detected are those from fuel that has settled and accumulated in the soil, making it difficult for mangrove plants to absorb water and other minerals.
“As a result, over time, the oil will be absorbed by the plants and enter the cambium tissue, plant cells become damaged, leaves turn yellow and fall, plants dry out, and eventually die,” he said.
The affected mangrove plants are located across an area of 6–60 are (600–6,000 square metres), encompassing both the intensive area and dispersed zones impacted by hydrocarbon compounds.
The research team at Udayana University’s Agricultural Hospital included Dr Listihani, Ni Nyoman Sista Jayasanti, Restiana Maulinda, Wafa’ Nur Hanifah, and Yuli Evrianti Br Gukguk.