Physical, Bio-Optical State and Correlations in North–Western European Shelf Seas

Garaba, Shungudzemwoyo P.; Voß, Daniela; Zielinski, Oliver

doi:10.3390/rs6065042

Cited by 29 publications

(28 citation statements)

References 53 publications

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“…The distribution of DOM in the water column is driven by several processes and, while upwelling can bring DOM to the surface, riverine input of DOM, and therefore CDOM and FDOM, leads to an increase in near coastal areas. Open waters are typically characterized by lower concentrations of DOM than coastal and estuarine waters (Garaba et al, 2014b). Our SML example from the offshore North Sea, with its lower content of humic-like fractions compared to coastal Jade Bay (Figure 3), is consistent with this generality.…”

Section: Eemssupporting

confidence: 74%

Influence of solar radiation on biogeochemical parameters and fluorescent dissolved organic matter (FDOM) in the sea surface microlayer of the southern coastal North Sea

Miranda

Mustaffa²,

Robinson³

et al. 2018

Elem Sci Anth

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Miranda, ML, 2018 Influence of solar radiation on biogeochemical parameters and fluorescent dissolved organic matter (FDOM) in the sea surface microlayer of the southern coastal North Sea. Elem Sci Anth, 6: 15. DOI: https://doi.org/10.1525/elementa.278 IntroductionThe sea surface microlayer (SML), defined here as the upper 50-100 µm of the water column, is an important habitat of the ocean where air-sea exchange and transformation processes take place (Wurl et al., 2016). Compounds from natural and anthropogenic sources accumulate within the SML enhancing their concentrations in comparison with the water column. The relative abundance of organic matter within the SML provides a diverse range of substrates for the growth of surface-dwelling heterotrophic microorganisms (Reinthaler et al., 2008).Among the sources of organic substrates in the SML is the dissolved organic matter (DOM; (Cunliffe et al., 2013). DOM is a large mix of organic compounds, mainly the products of biodegradation processes, and is comprised of carbohydrates, proteins, lignin, organic acids, and humic substances (Zhi et al., 2015). Two optically active components of DOM are known: the colored dissolved organic matter (CDOM) and the fluorescent dissolved organic matter (FDOM). CDOM includes materials that are capable of absorbing light, while FDOM refers to the mix of compounds that can absorb light, emitting fluorescence at certain wavelengths according to the presence of diverse chemical functional groups (Coble, 1996;Stedmon and Nelson, 2015). The SML is a highly dynamic and complex habitat in which several processes transform the DOM. These transformations are triggered by the environmental factors of wind, solar radiation, and light availability, as well as by microbial activity (Cunliffe et al., 2013).Light availability in the water column is controlled by two physical processes, absorption and scattering (Kirk, We investigated the influence of solar radiation on biogeochemical parameters of the sea surface microlayer (SML), including the spectroscopic composition of FDOM, and biotic and abiotic parameters. We calculated the humification index, biological index, and recently produced material index from the ultraviolet spectra to characterize the dynamic environment of the SML. The humification index ranged from 4 to 14 in the SML and 14 to 22 in underlying water (ULW). An inverse relation for this index as a function of solar radiation was observed, indicating photochemical decomposition of complex molecules present in fluorescent dissolved organic matter (FDOM). The biological index (along Leg 2) ranged from 1.0 to 2.0 for the SML and 1.0 to 1.5 for ULW. The index for recently produced material ranged from 0.25 to 0.8 for the SML and 0.5 to 1.0 for ULW. The FDOM enrichment process of the SML was influenced by the photochemical decomposition of highly aromatic-like fluorophores, as indicated by the calculated indices. Fluorescence intensity increased for humic C peaks (>0.5 Raman units) in the North Sea samples and for humic M peaks (>1....

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Section: Eemssupporting

confidence: 74%

Influence of solar radiation on biogeochemical parameters and fluorescent dissolved organic matter (FDOM) in the sea surface microlayer of the southern coastal North Sea

Miranda

Mustaffa²,

Robinson³

et al. 2018

Elem Sci Anth

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“…Absorbance values A(λ) were baseline corrected and then converted to the absorption coefficient a CDOM (λ) according to a CDOM (λ) = 2.303 × A(λ)/l, where λ is the wavelength and l is the path length of the cuvette in meters (Kirk, 2011). Based on this spectral information the CDOM absorption coefficient at 275 nm and 440 nm as well as the spectral slope (S CDOM ) in the spectral range of 275-295 nm were deduced (Garaba et al, 2014). Additionally the slope ratio (S R ) defined by Helms et al (2008) as the ratio S CDOM(275-295 nm) /S CDOM(350-400 nm) was derived.…”

Section: Quantitative and Qualitative Analysis Of Dissolved And Partimentioning

confidence: 99%

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

et al. 2017

Self Cite

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This study addresses key processes in high-energy beach systems using an interdisciplinary approach. We assess spatial variations in subsurface pore water residence times, salinity, organic matter (OM) availability, and redox conditions and their effects on nutrient cycles as well as on microbial community patterns and microphytobenthos growth. At the study site on Spiekeroog Island, southern North Sea, beach hydrology is characterized by the classical zonation with an upper saline plume (USP), a saltwater wedge, and a freshwater discharge tube in between. Sediment and pore water samples were taken along a cross-shore transect from the dunes to the low-water line reaching sediment depths down to 5 m below sediment surface. Spatial variations in pore water residence time, salinity, and organic matter availability lead to steep redox and nutrient gradients. Vertical and horizontal differences in the microbial community indicate the influence of these gradients and salinity on the community structure. shoreline. We propose that this nutrient efflux triggers growth of microphytobenthos on sediment surfaces of the discharge zone. A first comparison of nutrient discharge rates of the beach site with a nearby sandy backbarrier tidal flat margin indicates that the beach system might be of less importance in supplying recycled nutrients to nearshore waters than the backbarrier tidal flat area.

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“…Although more sophisticated instruments are commercially available, Secchi disks are still being widely and regularly utilized to measure water transparency for oceanography and limnology. Secchi disk depth (SDD) is a relative indicator of the vertical visual clarity of light and also an indicator of trophic level [8][9][10][11]. …”

Section: Introductionmentioning

confidence: 99%

MODIS-Based Mapping of Secchi Disk Depth Using a Qualitative Algorithm in the Shallow Arabian Gulf

Kaabi¹,

Zhao²,

Ghedira³

2016

Remote Sensing

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Abstract:Regionally calibrated algorithms for water quality are strongly needed, especially for optically complex waters such as coastal areas in the Arabian Gulf. In this study, a regional qualitative algorithm was proposed to retrieve seawater transparency, with Secchi disk depth (SDD) as a surrogate, in the Arabian Gulf. A two-step process was carried out, first estimating the diffuse attenuation coefficient of downwelling irradiance at 490 nm (K d _490) from MODIS/Aqua imagery and then SDD based on empirical correlations with K d _490. Three satellite derived K d products were tested and assessed against a set of in situ measurements, and one from a semi-analytical algorithm based on inherent optical properties gave the best performance with a R 2 of 0.62. Comparisons between the performances of SDD models developed in this study and those established in other regions indicated higher accuracy of our proposed model for the Gulf region. The potential factors causing uncertainties of the proposed algorithm were also discussed. Seasonal and inter-annual variations of SDD over the entire Gulf were demonstrated using a 14-year time series of MODIS/Aqua data from 2002 to 2015. High SDD values were generally observed in summer while low values were found in winter. Inter-annual variations of SDD did not shown any significant trend with exceptions during algal bloom outbreaks that resulted in low SDD.

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Physical, Bio-Optical State and Correlations in North–Western European Shelf Seas

Cited by 29 publications

References 53 publications

Influence of solar radiation on biogeochemical parameters and fluorescent dissolved organic matter (FDOM) in the sea surface microlayer of the southern coastal North Sea

Influence of solar radiation on biogeochemical parameters and fluorescent dissolved organic matter (FDOM) in the sea surface microlayer of the southern coastal North Sea

The drivers of biogeochemistry in beach ecosystems: A cross-shore transect from the dunes to the low-water line

MODIS-Based Mapping of Secchi Disk Depth Using a Qualitative Algorithm in the Shallow Arabian Gulf

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