| The Southern Ocean is not only the confluence area of the world oceans,but also the sea area where the upper and deep oceans exchange fiercely.Trace elements were essential nutrients for organisms life activities in marine biogeochemical cycles and tracers of various dynamic processes.It involved physical,chemical and biological processes such as the atmosphere,sediments,melting snow and ice,plankton and water mass mixing.Studying the concentration and distribution of trace elements in the surface waters of the Southern Ocean in different years is of great significance for exploring the contribution of various life activities to trace elements and the marine biogeochemical cycle of trace elements in order to deepen Understanding the role of trace elements in the marine biogeochemical cycle at a high level will provide more data for future development of Antarctic marine biological resources and marine environment research.In this paper,copper,lead,cadmium,and arsenic are selected as the research objects.In the Southern Ocean,the Shetland Islands(60°-65°S,55°-65°W),the South Orkney Islands(58°-62°S,40°-50°E),and the waters around the west side of the Prydz Bay(62°-68°S,50°-72°E)were set up with multiple sampling sections to collect surface layers.For seawater samples,the content of copper,lead,cadmium,and arsenic in seawater samples were measured by atomic fluorescence spectrophotometry and graphite furnace atomic absorption spectrophotometry.At the same time,high-performance liquid chromatography-inductively coupled plasma mass spectrometry(HPLC-ICP-MS)was used.Combined techniques to establish four arsenic species [As(?)],arsenate [As(?)],monomethylarsenate(MMA),and dimethylarsenate(DMA)in the surface waters of the Southern Ocean The method of determination andanalysis was used to analyze the concentration levels,regional distribution characteristics and seasonal changes of these trace elements and arsenic species in different sea areas.The main results and conclusions were:(1)In the summer of 2018/19,the average concentrations of Cu,Pb,Cd,and As in the surface waters of the South Sea Shetland Islands,South Orkney Islands,and the western waters around the Prydz Bay were 1.09 ?g / L and 1.16 ?g / L,0.3 ?g / L and 0.31 ?g / L,0.062 ?g / L and 0.06 ?g / L,2.83 ?g / L and 2.72 ?g / L,1.2 ?g / L and 1.58 ?g / L,0.39 ?g / L and 0.32 ?g / L,0.064 ?g / L and 0.07 ?g / L,2.82 ?g / L and 2.61 ?g / L,1.44 ?g / L and 1.19 ?g / L,0.25 ?g / L and 0.34 ?g / L,0.06 ?g / L and 0.07 ?g / L,3.52?g / L and 3.27?g / L.Compared with previous studies,the concentration of copper and lead is higher in this study.The concentrations of cadmium and arsenic are similar to other studies.The reasons for the differences are the sampling year,sampling method,measurement method,and area.Location matters a lot.(2)Compared with 2018,the average concentrations of copper,lead,and cadmium in the surrounding areas of the South Shetland Islands,South Orkney Islands,and the western side of the Prydz Bay have shown an overall upward trend in 2019.Compared with the other two seas,the overall concentration is higher.This study believes that this has a lot to do with the lower latitude of the South Orkney Islands.However,in the three seas,the concentration in 2019 shows a downward trend compared to 2018.Moreover,Prydz Bay has the highest overall concentration.(3)In terms of changes in latitude and longitude,the concentrations of trace elements are higher in the middle and high latitudes on the west side of the South Shetland Islands and the Prydz Bay,and the element concentrations in different years on the east and west sides are significantly different.The low latitudes of the South Orkney Islands Concentrations are higher,with copper and lead west than east,and cadmium and arsenic the opposite.In terms of offshore distance,the concentration in the waters near the South Shetland Islands is higher,and the concentration in the waters near the South Orkney Islands is higher.The concentrations of lead and arsenic are opposite.The west side of the Prydz Bay is near the edge of the continental shelf.Cadmium concentration is low,arsenic is the opposite.(4)Trace elements in Marine organisms play a crucial role in geochemistry,especially the nutrient elements such as copper and cadmium,a small amount of intakecan promote a variety of life activities of planktonic animals and plants,and the enrichment of arsenic and lead in organism can also produce negative effect,this study by discussing the source of the trace elements and factors that influence the concentration change think planktonic life activities of animals and plants,seasonal change and human activities result in ntu is main cause of the change of the concentration of trace elements in sea water.(5)The arsenic species in the three different sea areas of the South Shetland Islands,the South Orkney Islands,and the west side of the Prydz Bay exist as DMA with lower toxicity,followed by As(?),and As(?),which is the most toxic It is low in content and not detected by MMA,which indicates that the arsenic species in seawater is at a low level of toxicity during the biogeochemical cycle of the Southern Ocean,and it will hardly affect the marine ecosystem of the Southern Ocean.The experimental results and conclusions in this article have important theoretical and practical significance for understanding the concentration levels of these trace elements in the Southern Ocean,and studying the distribution characteristics of trace element concentrations,and to protect the Antarctic marine environment and prevent the Antarctic climate.Changes in the environment and endangering the survival of Antarctic organisms and humans,as well as predicting the trend of concentration changes of trace elements in the Southern Ocean,revealing in depth the role of trace elements in the structure and function of marine biological communities,and the role of biogeochemical cycles Important theoretical significance. |
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