Alkaline phosphatase (ALP) is a hydrolase that releases phosphate, a crucial nutrient supporting formation of many macromolecules. The oligotrophic sediments of Central Indian Basin (CIB) were examined for the extent of ALP activity in 20 cores up to 20cm depth along with other biogeochemical parameters. Northern and southern stations distinctly clustered based on pore water phosphorus (P) concentrations. ALP appeared more active in south due to more P and organic carbon (C) limitation. Central transition profiles revealed interesting mixed diagenetic and geothermal influence. Inter- and intrazonal differences suggest that broadly established paradigms applicable to water columns may deviate in space and time in sedimentary systems. Gross differences in redox status could govern differential response in ALP activity under similar hydrostatic pressure. Hydrothermal scavenging reactions striping soluble P from pore water might be widespread in CIB albeit at extreme low intensities. ALP might redissolve the precipitated P and make it reavailable to microbes.
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