Dissolved inorganic nutrients in the western Mediterranean Sea (2004–2017)

Malek Belgacem,Francesco Acri,Mireno Borghini,Alberto Ribotti,Bruno Pavoni,Katrin Schroeder,Jacopo Chiggiato,Gabriella Cerrati,Siv K Lauvset,Stefano Cozzi,Marta Álvarez

doi:10.5194/essd-12-1985-2020

Abstract

Abstract. Long-term time series are a fundamental prerequisite to understanding and detecting climate shifts and trends. Understanding the complex interplay of changing ocean variables and the biological implication for marine ecosystems requires extensive data collection for monitoring, hypothesis testing, and validation of modelling products. In marginal seas, such as the Mediterranean Sea, there are still monitoring gaps, both in time and in space. To contribute to filling these gaps, an extensive dataset of dissolved inorganic nutrient observations (nitrate, phosphate, and silicate) was collected between 2004 and 2017 in the western Mediterranean Sea and subjected to rigorous quality control techniques to provide to the scientific community a publicly available, long-term, quality-controlled, internally consistent biogeochemical data product. The data product includes 870 stations of dissolved inorganic nutrients, including temperature and salinity, sampled during 24 cruises. Details of the quality control (primary and secondary quality control) applied are reported. The data are available in PANGAEA (https://doi.org/10.1594/PANGAEA.904172, Belgacem et al., 2019).

Highlights

Dissolved inorganic nutrients play a crucial role in marine ecosystem functioning
The median and median absolute deviation (MAD) were computed by classes of pressure: we considered outliers to be any atypical observation and any value that departs from the median by more than three MADs in the different pressure ranges for each cruise
Four cruises were not considered in the crossover analysis: cruises no. 7 and no. 11 do not have enough stations > 1000 db, while cruises no. 19 and no. 21 were outside the spatial coverage of the reference cruises

Summary

Introduction

Dissolved inorganic nutrients play a crucial role in marine ecosystem functioning. They serve as regulators of ocean biological productivity and are trace elements for biogeochemical cycling as well as for natural and anthropogenic sources and transport processes (Béthoux, 1989; Béthoux et al, 1992). They are non-conservative tracers, since their distribution varies according to both biological (such as primary production and respiration) and physical (such as convection, advection, mixing, and diffusion) processes. Dissolved inorganic nutrients may be used as tracers of water masses like salinity and temperature to assess mixing processes and to understand the biogeochemical circumstances of their formation regions. Monitoring gaps still remain in both time and space, especially for marginal seas such as the Arctic Ocean or the Mediterranean Sea

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Conclusion