Description: Expansion (version 2.0) of the original Land2Sea database of exorheic rivers (Peucker-Ehrenbrink, 2009, doi:10.1029/2008GC002356) that contains information on 1519 rivers, with additional literature estimates of basin size, water discharge (runoff) under current conditions and prior to human intervention, suspended sediment discharge under current conditions and prior to human intervention, estimate of sediment bedload flux, dissolved strontium concentration and radiogenic isotope value as well as particulate (silt or clay) neodymium concentration, isotope composition and Nd model ages. A large addition to the original river database that contains a significant amount of data from the compilation of Meybeck and Ragu (1996) is from Milliman and Farnsworth (2011). The compilation is not yet geo-referenced. The 2156 rivers are sorted alphabetically within each large-scale drainage region (Graham et al., 1999, 2000). In addition, the compilation includes data on sizes of, and sediment discharge from 48 small islands in Oceania with very high sediment yields. Any errors in transcribing data or converting units from their primary sources into this compilation are entirely mine. Acknowledgements: BPE acknowledges financial support from NSR-EAR-0087697, -0125873, -1226818 and ICER-1639557, as well as from WHOI's Investment in Research and Development Fund.

Description: Wildfires and incomplete combustion of fossil fuel produce large amounts of black carbon. Black carbon production and transport are essential components of the carbon cycle. Constraining estimates of black carbon exported from land to ocean is critical, given ongoing changes in land use and climate, which affect fire occurrence and black carbon dynamics. Here, we present an inventory of the concentration and radiocarbon content (∆14C) of particulate black carbon for 18 rivers around the globe. We find that particulate black carbon accounts for about 15.8 ± 0.9% of river particulate organic carbon, and that fluxes of particulate black carbon co-vary with river-suspended sediment, indicating that particulate black carbon export is primarily controlled by erosion. River particulate black carbon is not exclusively from modern sources but is also aged in intermediate terrestrial carbon pools in several high-latitude rivers, with ages of up to 17,000 14C years. The flux-weighted 14C average age of particulate black carbon exported to oceans is 3,700 ± 400 14C years. We estimate that the annual global flux of particulate black carbon to the ocean is 0.017 to 0.037 Pg, accounting for 4 to 32% of the annually produced black carbon. When buried in marine sediments, particulate black carbon is sequestered to form a long-term sink for CO2.

Description: The SO-84 cruise from Las Palmas to Cape Town studied the underwater volcanism associated with the St Helena hotspot. Wide-spaced grid mapping of a region south and west of St Helena island identified three previously unknown hotspot volcanoes (which we named Josephine 16°27'S-9°W, Jade 16°13'S-7°46'W and Benjamin 16°12'S-8°31'W) and several older, probably near-ridge-generated seamounts. The newly discovered hotspot seamounts, and the previously-known seamounts of Bagration, Bonaparte and Kutuzov were mapped and sampled. Onboard geochemical studies confirm that they all show trace-element (Rb, Nb, Y, Zr, Sr) enriched, hotspot magma-type compositions. Morphological studies and the state of the samples collected from the seamounts (all have at least 1 mm-thick Mn crusts) suggest that none of the volcanoes is presently active, and that the St Helena hotspot is probably extinct at the present time. Josephine appears to be the youngest volcano, and one dredge here yielded fossil hydrothermal material (Fe-hydroxides). To test the hypothesis that the extinction of the hotspot is due to its magmas being channelled to the Mid-Atlantic Ridge, several dredges were taken on the ridge opposite St Helena. Furthermore, in the proposed influence zone of the St Helena plume head, Grattan seamount (9°44'S-12°48'W) was also sampled to examine whether its composition has been affected by the St Helena plume. During the transit from Las Palmas to St Helena, several sediment cores were taken in 3000 m water depth close to the ridge axis for palaeoclimatological work.

Description: This data set describes geochemical samples collected from 25 rivers and 11 lakes throughout the Canadian Arctic Archipelago (CAA). CAA rivers were sampled as part of the Canadian Arctic Archipelago Rivers Program (CAA-RP) and the Canadian Arctic GEOTRACES program with access via land, water, and air during the summer seasons of August 1-September 9, 2014, and August 11-19, 2015. Time series observations were also collected from the Coppermine River in Kugluktuk, Nunavut (NU) (year-round; August 5, 2014 to August 23, 2016), and from Freshwater Creek in Cambridge Bay, NU (open water only; June 19, 2014 to September 16, 2016). Lake samples were collected opportunistically during float plane air-surveys in 2014 and 2015 as part of the CAA-RP study in the southern CAA. Precipitation was collected during two significant rain events in Kugluktuk, NU (August 25, 2015) and Cambridge Bay, NU (August 20, 2016). River water samples were collected according to methods developed by the Arctic Great Rivers Observatory (Arctic-GRO; http://www.arcticgreatrivers.org/); lake sampling followed the same general methods, with collection carried out in deeper waters away from the shore; rain samples were collected using an HCl cleaned plastic box and processed immediately the morning following the rain event in order to limit the influences of evaporation. Sampling and analytical methods are described in detail in Brown et al., 2020. This data set includes the raw data supplied in Supplementary Tables S2 (Geochemical Data for the CAA-Rivers Project, collected from 2014 - 2016) and S3 (Geochemical Time Series Data for the Coppermine River and Freshwater Creek collected from 2014 - 2016) that accompany Brown et al., 2020. In addition to geochemical observations, the following calculated parameters can be found in Supplementary Table S2 of Brown et al., 2020: drainage basin area; predominant bedrock lithology; percent coverage of lakes; and surficial geology characteristics. These parameters were determined for each river drainage basin as described in the text and associated references found in Brown et al., 2020.