Enrichment potential of carbon and metals through biogeochemical pools of particulate matter and organisms of the coastal and continental margin

Loads of trace metals and organic materials on the coastal and shelf waters of the Sunda Shelf from vast terrestrial input will affect the flux dynamic, especially through biogeochemical pools. The Sunda Shelf's biogeochemical pools (i.e., the reservoirs or storage spaces for materials such as carbon and trace metals) vary from coastal to pelagic systems. In this context, such pools can represent suspended particulate matter, sediment, water column, and trophic levels or communities of organisms. We hypothesized that the enrichment of carbon and trace metals would follow the nitrogen stable isotope enrichment. Based on the hypothesis, this study has the following purposes: 1) to assess whether trace metals and 613C enrichment follows the increase in trophic level; 2) to assess the correlation between trace metals and carbon or nitrogen stable isotope (613C or 615N) enrichment; and 3) to elucidate the potential of carbon and metals flow through the biogeochemical pools. We analyzed the isotope and trace metals properties of the biogeochemical pool of seagrass, suspended particulate matter (SPM), mollusk, and fish. We compared the trophic level value of each pool, its carbon isotope, and metal concentration. The result shows that the sources of carbon for consumers (i.e., mollusks and fish) are seagrass, particulate organic matter (POM), and SPM. SPM presents a plausible reservoir of carbon and nitrogen that can be utilized by mollusks. In addition, the potential sources of carbon and nitrogen for fish could be seagrass, POM, epiphytes, SPM, or even mollusks. Carbon enrichment occurred from the primary producers to the higher trophic levels. Nonetheless, solely cadmium (Cd) and iron (Fe) demonstrated a notable adverse association with 613C and 615N, correspondingly. This result suggests that the dispersion of these trace metals likely aligns with the trophic level.