Spatial variability in residence time of Beryllium in the Indian Ocean

Abstract

Residence time of an element in the ocean is a consequence of its chemical behaviour and the various biogeochemical processes governing its distribution, sources, and sinks. Precise estimation of the residence time of beryllium(Be) is necessary for its application as a tracer for understanding present and paleo-environmental processes. We utilise cosmogenic ¹⁰Be and terrestrially derived ⁹Be measurements from surface sediments to estimate the residence time of Be in the Indian Ocean. Significant variation in Be residence time is observed, which ranges between 370 and 620 years in the central Indian Ocean, 64–205 years in the Bay of Bengal, 41–117 years in the Andaman Sea, and 179–443 years in the Arabian Sea. Large heterogeneity in the residence time of Be can be attributed to its variable scavenging efficiency in different regions. Active scavenging of Be by sediment particles contributed through various major rivers draining into the northern Indian Ocean results in short residence time of Be. The results of this study have significant implications for the selection of sample sites and the use of Be as a tracer in paleo reconstructions.