Geochemistry of surface water of Wismar Bay (Germany), southern Baltic Sea@en

This investigation was carried out in order to evaluate diagenetic element fluxes and different fresh water sources, including submarine groundwater discharge, on the water column of the Wismar Bay (Germany), southern Baltic Sea. Surface and bottom water samples were collected on board of the RV Littorina (L19-06) and a rubber boat by using a submersible pump in May 2019. The water was pumped through a filter cartridge (1 µM pore size) into barrels. Water samples from the barrels were pumped through manganese-coated acrylic fibers to extract radium (Ra) isotopes (223Ra, 224Ra). The Ra isotopes were measured within 3 and 10 days using radium-delayed coincidence counters (RaDeCC). Subsamples were taken via syringe and filtered (0.45 µM, cellulose acetate disposable filters) for analysis of dissolved concentrations of major and trace elements and selected nutrients using ICP-OES (iCAP, 7400, Duo Thermo Fischer Scientific), dissolved inorganic carbon (DIC) and δ13CDIC using isotope gas mass spectrometry (MAT 253 coupled to a Gasbench II), and δ18OH2O, δ2HH2O using a CRDS system (laser cavity-ring-down-spectroscopy, PICARRO L2140- I).本研究旨在评估波罗的海南部德国维斯马湾（Wismar Bay）水柱的成岩元素通量及不同淡水来源（包括海底地下水排泄（submarine groundwater discharge））。2019年5月，研究团队搭乘"利托里纳号"科考船（RV Littorina，航次L19-06）与橡皮艇，采用潜水泵（submersible pump）采集表层与底层海水样品；采集的水体经孔径1 µm的滤筒（filter cartridge）注入储桶。随后将储桶内的水样通过涂锰丙烯酸纤维（manganese-coated acrylic fibers）以萃取镭（Ra）同位素（223Ra、224Ra），并采用镭延迟符合计数器（RaDeCC, radium-delayed coincidence counters）分别在采样后3天与10天内完成同位素检测。另通过注射器（syringe）采集分样，经0.45 µm醋酸纤维素一次性滤膜（cellulose acetate disposable filters）过滤后，开展以下分析：利用电感耦合等离子体发射光谱仪（ICP-OES，iCAP 7400 Duo，赛默飞世尔科技（Thermo Fischer Scientific））测定常量元素、微量元素与选定营养盐的溶解态浓度；采用与Gasbench II联用的MAT 253型同位素气体质谱仪（isotope gas mass spectrometry）测定溶解无机碳（DIC）与δ13CDIC；借助激光腔环衰荡光谱系统（CRDS，laser cavity-ring-down-spectroscopy，PICARRO L2140-I）测定δ18OH2O与δ2HH2O。