Abstract:

Mangrove, one of the most productive ecosystems, thrive along coastlines throughout most of the tropics and subtropics. Worldwide, major attention had been paid to the pristine mangroves with very limited focus on anthropogenically stressed mangroves due to complex interaction between mangroves and anthropogenic inputs, that makes them challenging for studying elemental biogeochemical studies. We have chosen Zhangjiang mangroves, Southeast China as our study site, a perfect blend of natural mangroves and anthropogenic inputs.

Two cruises were conducted during wet and dry seasons covering spatial and time series studies. Mixing together with effectiveness of other mechanisms (includes submarine groundwater discharge, biogeochemical processes, mangroves and anthropogenic inputs) were evident to control estuarine as well as mangrove creek DIC chemistry. The DIC-TAlk slopes identified sulfate reduction, denitrification as dominant biogeochemical processes controlling inorganic carbon biogeochemistry in this region with additional effects from carbonate dissolution in the estuary. The groundwater was significantly enriched in carbon than estuary and mangrove creek, but relationships between different carbon parameters with ²²²Rn highlighted signal for carbon removal from the estuary during wet season in contrast to mangrove creek, where groundwater impact was limited then. However, during dry season, groundwater played crucial role on mangrove creek carbon pool although removal of inorganic carbon in contrast to addition of organic carbon with adding groundwater were highlighted. Despite we have no wet season data, but during dry season flux quantification confirmed limited anthropogenic impacts on creek water carbon pool. Within the mangrove creek, excess CO₂ - AOU relationships confirmed organic matter respiration mediated CO₂ addition during both season. Additionally, relationships between ²²²Rn with pCO₂ and CH₄ proved significant groundwater impact during dry season. However, in estuary, addition via organic matter respiration for CO₂ and removal via aerobic oxidation for CH₄ were pronounced during dry season. Finally, mangrove-estuary interaction of dissolved carbon will also be discussed in the seminar.

Bio:

I received Ph.D. from Department of Marine Science, University of Calcutta, India in 2016. There my work included studying methane biogeochemistry in the Indian Sundarbans mangroves. The I moved to Geosciences Division, Physical Research Laboratory as postdoctoral fellow and worked on application of stables isotopes in studying different mechanisms involved in mangrove carbon biogeochemistry. In December, 2017, I joined at Ocean carbon group, State Key Laboratory of Marine Environmental Science, Xiamen University as postdoctoral fellow and still continuing my research here.