| Dimethylsulfoxide(DMSO),the main oxidation product of DMS,manifests so closely related to DMS that can indirectly affect the global sulfur cycle,climate and environment through the mutual transformation with DMS.Polar Seas are high-value production areas of DMS in the global ocean,which act highly sensitivity to global climate change,playing an important role in regulating and indicating global climate change.Studies on DMSO distributions and related influencing factors in polar regions are of vital importance in deepening the understanding of the importance of marine biogenic sulfur compounds to global sulfur cycle and climate environment.In this study,we determined the spatial distributions of dissolved DMSO(DMSOd)and particulate DMSO(DMSOp)in the northern Antarctic Peninsula during Chinese34th Antarctic expedition from January 1 to February 3,2018 and in the Pacific sector of Arctic during Chinese 10th Arctic expedition from August 24 to September 9,2019.Potential controlling factors of DMSO and the production capacity of DMSO in the waters of the two investigated areas were discussed.The main results are as follows:1.The concentrations of DMSOd and DMSOp in surface water of the northern Antarctic Peninsula during summer ranged from 1.03 to 22.20 nmol·L-1(5.35±4.16nmol·L-1)and from 0.03 to 13.28 nmol·L-1(4.72±3.84 nmol·L-1),respectively.Surface DMSOd gradually increased from west to east on accunt of surface salinity,and tendency that DMSOp first increased,then decreased and then increased from west to east derived from surface temperature(R=?0.601,P=0.039).DMSOp and Chl? were significantly correlated(R=0.715,P?0.01)in the eastern part of south Orkney Platform,area between the northern part of Powell Basin and the Scotia Sea,the Central Basin and Drake Passage,which were mainly related to the distribution of dinoflagellates and diatoms.The vertical distribution of DMSOd and DMSOp behaved basically consistent,decreasing with the depth in general.The high concentrations of DMSO in deep waters of Drake Passage and Bransfield Strait were mainly due to the presence of heterotrophic bacteria and copepod zooplankton there.And DMSO increased with water depth in Drake Passage,Bransfield Strait,area between northern part of the Powell Basin and the southern part of the Scotia Sea,the northeastern part of the South Orkney Platform,probably because of the transport of DMSO from the upper water and the production of DMSO by the re-suspension of sediments.2.The concentrations of DMSOd and DMSOp in summer surface sea water in the sector of Arctic Pacific Ocean were not detected to 5.91 nmol·L-1(1.34±1.34 nmol·L-1)and not detected to 13.08 nmol·L-1(3.26±3.43 nmol·L-1).DMSOd and DMSOp in surface water were in the roughly same distributions,and there were high concentrations of DMSO in the northwest part of Bering Basin,continental slope area,southeast part of Bering Strait,Herald Shoal and northern end of Chukchi Sea.DMSO concentration decreased with depth in the Bering Basin,Bering Sea east shelf,Bering Sea west shelf and Chukchi Sea shelf,but also increased with depth in the northern continental slope of Chukchi Sea and Bering Strait.High concentration of DMSO near the Yukon Estuary was due to the photooxidation of DMS to DMSO promoted by CDOM input from the river.DMSO around the southwest of St.Lawrence Island was higher than surrounding water,which was caused by the upwelling supplementing nutrients that promoted the growth of phytoplankton and release of DMSO.The higher concentration of DMSO in the northern continental slope of Chukchi Sea above 200 m mainly came from the photochemical oxidation and biological consumption of higher DMS concentration in this region.3.According to the correlation analysis,comparison of DMSO concentration and environmental parameters in the polar areas,it was found that the DMSO concentrations was in the order of northern Antarctic Peninsula>Chukchi Sea>Bering shelf>Bering Basin,which was mainly related to the co-determination of phytoplankton abundance and phytoplankton DMSO production capacity.Temperature was the main factor affecting the surface DMSO distribution in the northern Antarctic Peninsula(R=?0.601,P=0.039).The rich nutrients brought by the upwelling promoted the growth of phytoplankton,and the melting ice water could input nutrients and ice algae seeds to increase the abundance of phytoplankton in the affected area.The low temperature environment in the cold water mass was conducive to the large number of dinoflagellates with high DMSO production capacity.The releasing process of seafloor sediments was conducive to the increasement of DMSO in bottom water.These important marine processes mentioned above have an important impact on the synthesis and release of DMSO,resulting in the presence of high concentrations of DMSO in the affected areas. |
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