| dc.description.abstract | Industry and the community have carried out tin mineral exploration on Bangka Island for a long time. Industrial mining has been going on for 200 years, while community mining has been carried out illegally (Unconventional Mining/UM). UM has increased since the period of regional autonomy in 2008. UM is carried out using the land opening method. It has a significant impact on the damage to the tailing’s expanse. The land becomes nutrient-poor, and many basins are formed (kolong). Tailings (fine grain) are suspected of containing heavy metals because, naturally, heavy metals are contained in soil minerals. Several studies have indicated the contamination of heavy metals in marine waters and their accumulation in aquatic resources. One of the commercial resources is the gonggong conch (Laevistrombus canarium). This study reveals the level of heavy metal contamination and the biological aspects of the gonggong conch resource related to the presence of tin mining exploration.
The study was conducted by purposive sampling: areas affected by mining and far from mining activities. The samples used were sediment, seagrass and L. canarium. Sediment samples were taken at twelve points around Bangka Island. This sample describes the distribution of heavy metals on Bangka Island. L. canarium and seagrass data were collected using a quadratic transect (1 x 1m) in six L. canarium habitats. The research variables included measurements of heavy metal concentrations (Zn, Cu, Pb, Cd, Sn) in sediments and L. canarium (gills and meat), methionine and cystine in L. canarium (gills, meat) and hepatopancreas histology of L. canarium. The total heavy metals were measured according to APHA (2012) by Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-EOS). Amino acid preparation and measurement with modified AOAC (2005) method using Liquid chromatography-mass spectrometry (LC-MS). Statistical approach (Kruskal – Wallis and Pairwise Comparison test) was used to explain the effect of heavy metals due to mining activities on the habitat of L. canarium, the relationship between environmental conditions and the growth/health of L. canarium (population and structure/age group, amino acid content of methionine, cystine, and histology).
The analysis reveals that almost all sediment samples are contaminated with heavy metals (Zn, Cu, Pb, Cd, and Sn). Concentrations of Zn, Cu, and Pb consistently show relatively high values in the environs of Teluk Kelabat and Tanah Merah Beach, as locations around mining activities. Based on the Enrichment Factor (EF) category, Zn and Cu contamination in the research area was still relatively small (EF < 2), except for Pb, which had undergone high enrichment (EF 5-20). The high Pb still requires further research to find the cause. Is it related to the soil geology of the Bangka area as an indication of tailings waste or anthropogenic impact?. The presence of heavy metals in these sediments can still be classified as relatively safe when referring to quality standards such as CCME or ANZECC/ARMCANZ.
L. canarium is relatively low, with a density range of 6-8 ind/m2. The organism's condition also showed poor growth as indicated by the negative allometric growth form (b<3), and the body condition was classified as thin. A negative allometric is a growth characteristic where the length gain is faster than the weight. The growth and density of L. canarium at locations with high heavy metal content were relatively the same as in locations with low metal content. It indicates that environmental conditions, especially the impact of heavy metals, have not had a real impact on L. canarium life. Environmental conditions were generally good for L. canarium growth, although some areas had high turbidity (79 – 233 mg/liter). However, this variation was not thought to cause the growth of L. canarium, which was generally thin. The existence of relatively high exploitation is suspected to be one of the factors affecting the condition of L. canarium. It is reinforced by the determination of an imbalance in the recruitment process. The structure of cohort 2 (middle/intergenerational) is more dominant than cohort 1 (younger) and less than cohort 3 (adults), which is expected to create much regeneration.
Environmental conditions affect not only morphological conditions but also physiology. It is indicated by the content of methionine and cystine, which are toxic when interacting with heavy metals. The methionine and cystine in L. canarium showed significant variation between generations. However, there is no tendency to increase or decrease in the younger or older generation. It differs from heavy metals (Zn, Cu, and Pb), which tend to increase accumulation between generations. The content of methionine is relatively lower than cystine, especially in the gills. The flesh of L. canarium contains lower cystine than the gills. In this study, there were no differences in the concentration of amino acids and heavy metal accumulations based on different locations. The correlation between amino acids (methionine and cystine) and heavy metals does not always reveal a positive correlation, except for Pb, which is relatively consistent and quite strong positive. However, this study found an impairment in the hepatopancreas tissue structure of L. canarium. Damage characteristics include a dilated lumen, resorptive cells, and more vacuolation. Vacuolation is caused by the accumulation of toxic substances and fats in the hepatopancreas tubules and can interfere with the cellular metabolic processes. Damage occurred in all generations of L. canarium (cohorts 1,2, and 3) at the study site. The level of impairment varies from new to intensive. New or relatively early damage is characterized by inflammation of the plasma membrane or cell wall, while severe damage is characterized by thinning the tubules to cell lysis. Hepatopancreas tissue damage was extreme in L. canarium, which has a habitat in the Teluk Kelabat area compared to the South Bangka region.
Heavy metal contamination on Bangka Island occurred with mild to moderate contamination levels. However, it is still in the category of being relatively safe for the growth of L. canarium. Heavy metals have been accumulated in the body of L. canarium, which stimulate the content of amino acids (methionine and cystine). Hepatopancreas of L. canarium is indicated to have mild to extreme tissue damage and still needs further study of the mechanism of the damage process. | id |
