Zinc complexing ligands in rivers in pristine peatland areas in Borneo, and rivers with agricultural and industrial anthropogenic influence in Tropical South East Asia: Elucidating the connection to oceanic regional and global distributions of Zinc ligands and bioavailable Zinc

Organic complexing ligands dominate the chemical speciation of Zn in seawater globally, affecting its bioavailability and regulating its micronutrient role. We have shown that intermediate water masses in the West Pacific indicate a connection between point sources related to marginal seas, riverine matter, benthic fluxes, and continental shelves, with ligand concentrations and binding strengths evolving along water mass trajectories.

Here we will present results from recent studies in tropical South East Asia that explore rivers in pristine peatland areas in Borneo, and rivers near and around agricultural and industrial anthropogenic influence in Borneo, Singapore and Malaysia, with the aim of elucidating the importance of relatively fresh natural and agricultural land-based plant material and industrial anthropogenic material in the organic matter mix that the ligands are a part of. These results track the ligand concentration and binding strength of different sources of Zn complexing ligands obtained using ASV and modern comprehensive mathematical methods We will compare records of humic substances from coral cores near the mouth of these rivers, with the goal of ascertaining a possible link of humic substance concentrations and metal complexing ligands in the region. We will compare the results from these large sources of organic matter with the ligands observed in continental shelves, where the organic matter has suffered biochemical processes, with ligands observed in the West Pacific, after decades of bacterial respiration while travelling along water masses. We aim to compare these ligand in order to assess the relevance of these sources of complexing ligands to regulate regional and global distribution of Zn ligands and its bioavailable concentrations.