A First Global Oceanic Compilation of Observational Dissolved Aluminum Data With Regional Statistical Data Treatment

Large national and international observational efforts over recent decades have provided extensive and invaluable datasets of a range of ocean variables. Compiled large datasets, structured, or unstructured, are a powerful tool that allow scientists to access and synthesize data collected over large spatial and temporal scales. The data treatment approaches for any element in the ocean could lead to new global perspectives of their distribution patterns and to a better understanding of large-scale oceanic processes and their impact on other biogeochemical cycles, which may not be evident otherwise. Ocean chemistry Big Data analysis may not just be limited to distribution patterns, but may be used to assess how sampling efforts and analytical methodologies can be improved. Furthermore, a systematic global scale assessment of data is important to evaluate the gaps in knowledge and to provide avenues for future research. In this context, here we provide an extensive compilation of oceanic aluminum (Al) concentration data from global ocean basins, including data available in the GEOTRACES Intermediate Data product (Schlitzer et al., 2018), but also thus far unpublished data

The Cd isotope composition of atmospheric aerosols from the Tropical Atlantic Ocean

Stable isotope compositions can potentially be used to trace atmospheric Cd inputs to the surface ocean and anthropogenic Cd emissions to the atmosphere. Both of these applications may provide valuable insights into the effects of anthropogenic activities on the cycling of Cd in the environment. However, a lack of constraints for the Cd isotope compositions of atmospheric aerosols is currently hindering such studies. Here we present stable Cd isotope data for aerosols collected over the Tropical Atlantic Ocean. The samples feature variable proportions of mineral dust-derived and anthropogenic Cd, yet exhibit similar isotope compositions, thus negating the distinction of these Cd sources by using isotopic signatures in this region. Isotopic variability between these two atmospheric Cd sources may be identified in other areas, and thus warrants further investigation. Regardless, these data provide important initial constraints on the isotope composition of atmospheric Cd inputs to the ocean

High-resolution variability of dissolved and suspended organic matter in the Cape Verde Frontal Zone

21 pages, 8 figures, 4 tables.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)Distributions of dissolved (DOM) and suspended (POM) organic matter, and their chromophoric (CDOM) and fluorescent (FDOM) fractions, are investigated at high resolution (< 10 km) in the Cape Verde Frontal Zone (CVFZ) during fall 2017. In the epipelagic layer (< 200 m), meso- and submesoscale structures (meanders, eddies) captured by the high resolution sampling dictate the tight coupling between physical and biogeochemical parameters at the front. Remarkably, fluorescent humic-like substances show relatively high fluorescence intensities between 50 and 150 m, apparently not related to local mineralization processes. We hypothesize that it is due to the input of Sahara dust, which transports highly re-worked DOM with distinctive optical properties. In the mesopelagic layer (200-1500 m), our results suggest that DOM and POM mineralization occurs mainly during the transit of the water masses from the formation sites to the CVFZ. Therefore, most of the local mineralization seems to be due to fast-sinking POM produced in situ or imported from the Mauritanian upwelling. These local mineralization processes lead to the production of refractory CDOM, an empirical evidence of the microbial carbon pump mechanism. DOM released from these fast-sinking POM is the likely reason behind the observed columns of relatively high DOC surrounded by areas of lower concentration. DOM and POM dynamics in the CVFZ has turned out to be very complex, in parallel to the complexity of meso- and submesoscale structures present in the area. On top of this high resolution variability, the input of Sahara dust or the release of DOM from sinking particles have been hypothesized to explain the observed distributionsThis work was funded by Spanish National Science Plan research grants FERMIO (CTM2014–57334–JIN) and FLUXES (CTM2015-69392-C3), co–financed with FEDER funds, and e-IMPACT (PID2019-109084RB-C21 and –C22). RC, SV and NB were supported by predoctoral fellowships from the Spanish Ministry of Science and Innovation (BES-2016-076462, BES- 2016-079216 and BES-2016-077949). BF-C was supported by a Juan de la Cierva Formación fellowship (FJCI-641-2015-25712) and by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 834330 (SO-CUP). JA was partly supported by the project SUMMER (AMD-817806-5) from the European Union’s Horizon 2020 research and innovation programPeer reviewe

Pump-underway ship intake: An unexploited opportunity for Marine Strategy Framework Directive (MSFD) microplastic monitoring needs on coastal and oceanic waters.

Broad scale sampling methods for microplastic monitoring in the open ocean waters remain a challenge in oceanography. A large number of samples is required to understand the distribution, abundance and fate of microplastic particles in the environment. Despite more than a decade of widespread study, there is currently no established time series of microplastic measurements and the research community is yet to establish a standardised set of methods that will allow data to be collected in a quick, affordable and interoperable way. We present a sampling technique involving the connection of a custom-built microplastic sampling device to the pump-underway ship intake system of a research vessel (RV) as an unexploited opportunity for oceanic monitoring needs concerning microplastic abundance and distribution. The method is cost effective, highly versatile and accurate, and is able to sample particles down to 50μm from opportunity platforms, thus contributing to an emerging area of study, and in particular helping to increase the monitoring reporting of data, and thereby serving as a valuable aid for the implementation of the Marine Strategy Framework Directive (MSFD). Sampling was performed during three consecutive oceanographic cruises in the subtropical NE Atlantic over a year, sampling subsurface waters (4 m depth) during navigation and while on coastal and oceanic stations. Microplastic particles were found in all stations and transects sampled. Fibres (64.42%) were predominant over fragments (35.58%), with the concentration values falling within the ranges of data reported for other areas of the Atlantic

Atmospheric fluxes of soluble nutrients and Fe: More than three years of wet and dry deposition measurements at Gran Canaria (Canary Islands)

Dust inputs to the oligotrophic waters of the subtropical North Atlantic are of significant importance to the biogeochemistry of the region. In this work, we present fluxes of particles, soluble elements (H+, major ions, Fe and organic ions) in dry deposition (DD) and wet deposition (WD) samples collected between September 2012 and April 2016. Positive Matrix Factorization Model (PMF) indicated four dominant factors influencing the elemental concentrations: marine, crustal and two anthropogenic. Soluble Fe fluxes appear to be affected predominantly by aerosol particle type, with higher values observed at lower dust loading. Although WD fluxes made up only a small fraction of total particle fluxes (12%), they represented an important input of soluble Fe and other nutrients such as nitrate (more than 50% of total amount deposited). This significant contribution to total deposition fluxes may have important consequences for primary production in the surface ocean. Mineral dust is the primary source of soluble atmospheric P to the north Atlantic, which is a region that is already P stressed. Our data show that DD dominates the total flux of soluble P to this area (∼87% of the total flux) and it may have a bigger impact in the diazotroph communities during the summer months when the water column is more stratified and nutrient inputs from deeper water are restricted

Fluxes of particles and soluble elements in dry and wet deposition samples collected between September 2012 and April 2016 at Gran Canaria, Canary Islands.

Steps to reproduce - Sampling sites and aerosol collection Tafira (TF) station (28º 06' N, 15º 24' W; 269 m a.s.l) is an urban background site subject to anthropogenic influence and situated within the marine boundary layer (<1800 m a.s.l). A Total Suspended particles (TSP) concentration Time-series has been recorded since 1 December 2003(see Gelado-Caballero et al., 2012; López-García et al., 2013). High volume (60 m3 h-1) aerosol collectors (MCV, model CAV-A/M) were used to collect aerosol samples for TSP in air on glass fibre filters (Whatman GF/A). TSP concentrations were measured following the procedure described in Gelado-Caballero et al. (2012). For deposition measurements, an automatic wet and dry sampler (ARS 1000, MTX Italy) with cubic containers having a surface area of 490 and 660 cm2, respectively was used. The instrument is equipped with a rain sensor. The aerosols collected in the deposition samples were quantified by gravimetry after filtering. Nucleopore filters were dried under a Class100 horizontal laminar flow bench and weighed with an accuracy of ±0.01 mg (Sartorius CP225D), before washing with 0.1 M hydrochloric acid (Suprapure, Merck) prior to use. Dry deposition (DD) samples were collected throughout the period from September 2012 to April 2016 at Tafira, in 92 samples representing average time periods ranging of 11 days but only since February 2013 soluble elements were analysed. Wet deposition (WD) samples were collected after each rainfall over the same period (n=125) representing average sampling periods of 2 days. - Chemical Analysis Soluble major ions, soluble Fe and pH were determined in the deposition samples. For DD samples, 150 mL was added to the bucket trying to wash all the particles deposited on the walls. The bucket was placed in an orbital shaker for 15 minutes to extract all the soluble elements, after that, the pH was measured and the sample was filtered using an acid clean Nucleopore filter (47 mm diameter and 0.2 µm pore size). WD samples were analysed just after the rain event and the same type of filter was used. pH in wet and dry deposition unfiltered samples were determined using a combined electrode (Aquatrode Plus, Metrohm). Soluble major ions were determined using two ion chromatographers (883 Basic IC Plus, Metrohm), a Metrosep ASupp 4 column for anion separation (fluoride, formate, chloride, bromide, nitrite, nitrate, phosphate, sulphate, and oxalate) and a Metrosep C4 column for cation separation (sodium, ammonium, potassium, calcium and magnesium) with a detection limit of 1 µg L-1. Because most of the phosphate concentrations in wet and dry deposition samples were below the detection limits of the IC, a nanomolar nutrient system was used (Patey et al., 2008). Soluble Fe was measured using a FiALab-3500 flow-injection analysis (FIA) system adapted to measure Fe using luminol chemiluminescence

Cape Verde Frontal Zone in summer 2017: lateral transports of mass, dissolved oxygen and inorganic nutrients

The circulation patterns in the confluence of the North Atlantic subtropical and tropical gyres delimited by the Cape Verde Front (CVF) were examined during a field cruise in summer 2017. We collected hydrographic data, dissolved oxygen (O2) and inorganic nutrients along the perimeter of a closed box embracing the Cape Verde Frontal Zone (CVFZ). The detailed spatial (horizontal and vertical) distribution of water masses, O2 and inorganic nutrients in the CVF was analyzed, allowing for the independent estimation of the transports of these properties in the subtropical and tropical domains down to 2000 m. Overall, at surface and central levels, a net westward transport of 3.76 Sv was observed, whereas at intermediate levels, a net 3 Sv transport northward was obtained. We observed O2 and inorganic nutrient imbalances in the domain consistent with O2 consumption and inorganic nutrient production by organic matter remineralization, resulting in a net transport of inorganic nutrients to the ocean interior by the circulation patterns