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Marine continental shelf sediments with high deposition rates may provide useful archives of rapid geomagnetic secular variation as long as the primary magnetization is not altered substantially by diagenesis. To quantify the effects of sulfate (SO42‐) reduction, which is a dominant early diagenetic process in such sediments, on paleomagnetic recording, we analyzed four 6‐m long sediment cores from the eastern Mediterranean shelf. Two cores did not reach the methanogenic zone and are characterized by continuous organoclastic sulfate reduction (OSR), while the other two have a distinctive shallow sulfate‐methane transition zone (SMTZ). Age models based on 28 radiocarbon ages indicate steady deposition rates with spatially varying age spans, which suggest that different parts of the shelf stopped accumulating sediments at different times during the Holocene. The upper sediment column in all cores is dominated by detrital titanomagnetite and biogenic magnetite. OSR‐affected sediments record continuous (titano) magnetite dissolution, which resulted in steady magnetic susceptibility and remanence decreases. For cores that reach the methanogenic zone, similar behavior is observed at or above the STMZ, but magnetic properties stabilize at greater depths. Paleomagnetic directions in these sediments are more coherent, with better agreement with geomagnetic models than sediments affected by OSR. We suggest that methane‐rich sediments with a shallow SMTZ and high sedimentation rates can better preserve primary paleomagnetic signals than OSR‐dominated sediments due to a lack of dissolved sulfide in the main methanogenic zone, and that a susceptibility decline with depth should be a warning sign for paleomagnetic studies. Plain Language Summary: It has long been recognized that seafloor sediments provide continuous records of variations of Earth's magnetic field. Marine sediments have, thus, been used to explore Earth's magnetic field behavior throughout geological history. The classical view on how sediments acquire a magnetization in aquatic environments involves physical forces that rotate magnetic particles toward the field direction as they sink. However, biochemical processes associated with microbial respiration may distort primary depositional magnetic information and even remagnetize it. We explore here how sulfate reduction, which is one of the most dominant biochemical processes in global continental shelf marine environments, affects sediment magnetic properties and the ability to accurately record magnetic information. We analyzed four sediment cores from the Southeastern Mediterranean shelf, which were deposited under different sulfate reduction regimes. We show that continuous sulfate reduction significantly changes the magnetic mineralogy and, therefore, hampers preservation of sedimentary paleomagnetic records. We also show that to obtain reliable high‐resolution sedimentary paleomagnetic data, sulfate should be consumed as early as possible after deposition. Such conditions occur when methane fluxes from below reach shallow sulfate‐rich sediments. Key Points: Correlation between early diagenetic zones and mineral magnetic properties in Holocene southeastern Mediterranean shelf sedimentsContinuous (titano) magnetite dissolution during organoclastic sulfate reduction (OSR) distorts the primary paleomagnetic signalSediments with a shallow SMTZ and high sedimentation rates can better preserve paleomagnetic signals than OSR‐dominated sediments [ABSTRACT FROM AUTHOR]

Iron emissions from human activities, such as oil combustion and smelting, affect the Earth's climate and marine ecosystems. These emissions are difficult to quantify accurately due to a lack of observations, particularly in remote ocean regions. In this study, we used long‐term, near‐source observations in areas with a dominance of anthropogenic iron emissions in various parts of the world to better estimate the total amount of anthropogenic iron emissions. We also used a statistical source apportionment method to identify the anthropogenic components and their sub‐sources from bulk aerosol observations in the United States. We find that the estimates of anthropogenic iron emissions are within a factor of 3 in most regions compared to previous inventory estimates. Under‐ or overestimation varied by region and depended on the number of sites, interannual variability, and the statistical filter choice. Smelting‐related iron emissions are overestimated by a factor of 1.5 in East Asia compared to previous estimates. More long‐term iron observations and the consideration of the influence of dust and wildfires could help reduce the uncertainty in anthropogenic iron emissions estimates. Plain Language Summary: Human activities, such as smelting and oil combustion, release smoke and particles into the atmosphere. These particles often contain iron, which not only absorbs sunlight, contributing to atmospheric warming, but also serves as a nutrient for phytoplankton in various ocean regions. However, the precise extent of human‐induced iron emissions remains uncertain due to a lack of comprehensive monitoring data. In this study, we leverage a global data set of iron observations to refine our estimates of iron emissions attributed to human activities. Additionally, we examine other co‐released substances, such as carbon and nickel, to identify specific emission sources of iron. We employ statistical techniques to distinguish human‐caused iron emissions from those originating from natural sources like dust and wildfires. Moreover, we utilize iron oxide observations to constrain emissions originating from East Asia and Norway, which are estimated to originate largely from smelting emissions. Through the analysis of long‐term data sets, we provide lower and upper bounds to human‐caused iron emissions. Furthermore, we investigate the impact of reduced observation numbers and a sparse network on the range of estimated iron emissions. Our findings highlight the critical role of observation quality in accurately assessing iron emissions from human activities. Key Points: Anthropogenic total iron emissions are constrained to a factor of 3 in most global regions using long‐term aerosol observationsThe number of sites, interannual variability, and site selection filter can affect the model‐observation comparison uncertainty by 15%–50%Smelting‐related emissions are constrained to a factor of 1.5 using iron oxide observations from East Asia [ABSTRACT FROM AUTHOR]

Sediment trap data set and 234Th profiles (deep water excesses and deficits) reveal that particulate organic carbon (POC) export at the highly oligotrophic Levantine Sea is dominated by lateral transport from the nearby margin. These intermediate nepheloid layers (INL) operate at multi‐depth, with the silt‐to‐clay size particulate matter (PM) fraction transported at water depths of about 100–500 m, while finer fraction arrives also at deeper depths. The shallow NIL is triggered by winter storms, manipulated by coastal flash floods and shelf resuspension and assisted by cross‐shore currents, which allow the arrival of PM at a distance of 50 km within about 10 days. The deeper INL could be related to sediments initially driven to depth by density currents. Our data show that inter‐annual differences in sediment trap fluxes were related to changes in both the intensity of coastal floods and current velocity. The frequent observation of deep‐water 234Th excesses during a (relatively) low export winter (2018) is related to lessened cleansing of the water column, that is, reduced removal of fine‐grained PM by sinking coarser‐grained material. These observations highlight the importance of winter storm intensity in the POC budget of marginal seas like the Levantine Basin (LB) even in areas with limited river discharge. This further suggests that the anticipated increase in extreme weather events due to the on‐going climate change should have an impact on this coastal‐deep sea conveyor and on POC export in the LB. Plain Language Summary: We present sediment traps and radioisotope results from the DeepLev marine station, the first deep water mooring to be deployed in the highly fragile ecosystem of the Levantine Basin (eastern Mediterranean Sea). Unlike the open ocean, particulate organic carbon export from surface to deep water is controlled by the transport of particulate matter from the nearby coast/continental shelf. We show that this land‐sea conveyor is nurtured by flash floods and shelf sediment resuspension, and is further manipulated by cross‐shore currents. The conveyor operates at multiple depths, with silt and clay transported sub‐horizontally from the shelf, arriving at DeepLev within ca. 10 days at 100–500 m depth (shallow intermediate nepheloid layer, INL), while colloids being carried through the whole water column (deep INL). The latter is probably related to particle‐laden density currents, which flow down submarine canyons, cutting into the nearby continental slope. Inter‐annual changes in winter events and cross‐shore current velocity result in significant changes of POC export intensity. This further implies that the predicted increase in the occurrence of extreme meteorological events could result in an enhanced transport of particular carbon, with important implications to the POC export in this and other marginal basins. Key Points: POC export in the Levantine Basin is controlled by lateral transport of multi‐depths intermediate nepheloid layers (INL)The shallow INL carries silt and clay from the coast and shelf, while the deep INL hauls colloids related to transport through submarine canyonsInter‐annual variability in winter event intensity results in lateral transport and vertical export variability [ABSTRACT FROM AUTHOR]

Processed and analyzed sea surface wave characteristics derived from an up-looking acoustic Doppler current profiler (ADCP) for the period 2016–2022 are presented as a dataset available from the public open-access repository of SEA scieNtific Open data Edition (SEANOE) at 10.17882/96904. The collected data include full two-dimensional wave fields, along with computed bulk parameters, such as wave heights, periods, and directions of propagation. The ADCP was mounted on the submerged Deep Levantine (DeepLev) mooring station located 50 km off the Israeli coast to the west of Haifa (bottom depth ∼1470 m). It meets the need for accurate and reliable in situ measurements in the eastern Mediterranean Sea as the area significantly lacks wave data compared to other Mediterranean sub-basins. The developed long-term time series of wave parameters contribute to the monitoring and analysis of the region's wave climate and the quality of wind–wave forecasting models. [ABSTRACT FROM AUTHOR]