POSTER Session 3

VARIABILITY OF BIOGEOCHEMICAL AND ABSORPTION PROPERTIES OF DIFFERENT SIZE FRACTIONS OF SUSPENSIONS IN THE WESTERN FJORDS OF SPITSBERGEN (SVALBARD) IN SUMMER IN 2022-2023

We investigated the variability of biogeochemical properties and light absorption coefficients of different-sized suspended particulate fractions in the western fjords of Spitsbergen (Horsund, Kongsfjorden and Isfjorden) during the summer seasons of 2022 and 2023. The study encompassed measurements of suspended particulate matter (SPM), including organic (POM) and inorganic (PIM) fractions, chlorophyll a (Tchla) concentration, and light absorption coefficients by particles (ap(l)), phytoplankton (aph(l)) and detritus (ad(l)). Samples were analyzed both unfiltered and fractionated by size of the suspended particles using cascading filtration (by nylon meshes and membrane filters with pores of 20, 5 and 2 microns). We quantified the contributions of four size fractions: pico-particles (0.2-2 microns), ultra-particles (2-5 microns), nano-particles (5-20 microns) and micro-particles (20-200 microns) to the total SPM, POM, PIM, Tchla and light absorption coefficients. The largest contribution to total SPM, POM, PIM and Tchla were found in the ultra-particles, averaging 51%, 39%, 56% and 47%, respectively. Pico-particles also made significant contribution (19%, 25%, 16% and 29%, respectively). The proportion of micro- and nano-particles changed from 12% to 17%. Notably, ultra-particles also dominated the light absorption coefficients at 443 nm (ap(443) – 59%, ad(443) – 62% and aph(443) – 44%, indicating their significant role in light attenuation in these fjords systems. The contribution to the total absorption of pico-particles was on average: 26%, 24% and 28% and nano-particles: 11%, 10% and 19%, respectively. The smallest proportion had micro-particles: 5%, 4% and 9%. This study underscores the critical influence of particle size on biogeochemical processes and light dynamics in Arctic marine environment.

Justyna Meler, Institute of Oceanology of Polish Academy of Sciences, Poland, [email protected], https://orcid.org/0000-0002-7112-5041

Joanna Stoń-Egiert, Institute of Oceanology Polish Academy of Sciences, Poland, [email protected]

Monika Zabłocka, Institute of Oceanology Polish Academy of Sciences, Poland, [email protected]

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