Pore water alkalinity below the permanent halocline in the Gdańsk Deep (Baltic Sea) - Concentration variability and benthic fluxes

Łukawska‐Matuszewska, Katarzyna; Graca, Bożena

doi:10.1016/j.marchem.2018.05.011

Cited by 25 publications

(10 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concentration of nutrients in pore water indicated 6.7 and 14 mg L −1 of phosphorus and nitrogen, respectively. These results are in agreement with that of Łukawska-Matuszewska et al (2018) concerning the sediments from the Baltic Sea, while the surface water showed concentrations of phosphorus and nitrogen to be around 13 and 50 times lower than that in pore water, respectively. The high concentration of nutrients in pore water is potentially related to the high concentrations of nitrogen and phosphorus in the sediments.…”

Section: Pore Watersupporting

confidence: 91%

“…Table 5 illustrates the concentration of trace elements, nutrients, organic pollutants and other parameters in the pore water extracted from Malmfjärden sediments. The pH was acidic (pH = 2.03), which may be due to the oxidation of iron sulfide, forming sulfuric acid when the sediments encounter atmospheric oxygen (Łukawska-Matuszewska et al, 2018). The trace element concentrations were in the order of Zn (70 µg L −1 ) > Pb (21 µg L −1 ) > As (15 µg L −1 ) -Cu (15 µg L −1 ) > Ni (8.7 µg L −1 ) -Cr (8.7 µg L −1 ) > Cd (0.64 µg L −1 ).…”

Section: Pore Watermentioning

confidence: 99%

“…Defining the composition as well as characterizing the physicochemical properties of the dredged sediments is therefore regarded as an essential step towards identifying the future route of sediments (Couvidat et al, 2018). Analysing the trace elements and organic-matter contents, nutrients and organic compounds is essential to identify potential end users and whether any prior treatment is needed (Mattei et al, 2016). High organic-matter content, nitrogen and phosphorus are essential for using the sediments in agriculture (Dang et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Characterization of dredged sediments: a first guide to define potentially valuable compounds – the case of Malmfjärden Bay, Sweden

et al. 2019

View full text Add to dashboard Cite

Abstract. Millions of tons of bottom sediments are dredged annually all over the world. Ports and bays need to extract the sediments to guarantee the navigation levels or remediate the aquatic ecosystem. The removed material is commonly disposed of in open oceans or landfills. These disposal methods are not in line with circular-economy goals and additionally are unsuitable due to their legal and environmental compatibility. Recovery of valuables represents a way to eliminate dumping and contributes towards the sustainable extraction of secondary raw materials. Nevertheless, the recovery varies on a case-by-case basis and depends on the sediment components. Therefore, the first step is to analyse and identify the sediment composition and properties. Malmfjärden is a shallow semi-enclosed bay located in Kalmar, Sweden. Dredging of sediments is required to recuperate the water level. This study focuses on characterizing the sediments, pore water and surface water from the bay to uncover possible sediment recovery paths and define the baseline of contamination in the water body. The results showed that the bay had high amounts of nitrogen (170–450 µg L−1), leading to eutrophication problems. The sediments mainly comprised small size particle material (silt, clay and sand proportions of 62 %–79 %, 14 %–20 %, 7 %–17 %, respectively) and had a medium–high level of nitrogen (7400–11 000 mg kg−1). Additionally, the sediments had little presence of organic pollutants and low–medium concentration of metals or metalloids. The characterization of the sediments displays a potential use in less sensitive lands such as in industrial and commercial areas where the sediments can be employed as construction material or as plant-growing substrate (for ornamental gardens or vegetation beside roads).

show abstract

Section: Pore Watersupporting

confidence: 91%

Section: Pore Watermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of dredged sediments: a first guide to define potentially valuable compounds – the case of Malmfjärden Bay, Sweden

et al. 2019

View full text Add to dashboard Cite

show abstract

“…This would then represent a fraction of the SO 2− 4 reduction that is not readily reversed through H 2 S oxidation upon reoxygenation of the water column. Due to incomplete descriptions of benthic processes in the model that was used, this hypothesis could not be tested (Gustafsson et al, 2014b), but the process has recently been identified as an important TA source in the Gdańsk Deep (Łukawska-Matuszewska and Graca, 2018).…”

mentioning

confidence: 99%

Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea

et al. 2019

View full text Add to dashboard Cite

Abstract. Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these concurrent changes has not yet been investigated in detail. A recent system-wide TA budget constructed for the past 50 years using BALTSEM, a coupled physical–biogeochemical model for the whole Baltic Sea area revealed an unknown TA source. Here we use BALTSEM in combination with observational data and one-dimensional reactive-transport modeling of sedimentary processes in the Fårö Deep, a deep Baltic Sea basin, to test whether sulfate (SO42-) reduction coupled to iron (Fe) sulfide burial can explain the missing TA source in the Baltic Proper. We calculated that this burial can account for up to 26 % of the missing source in this basin, with the remaining TA possibly originating from unknown river inputs or submarine groundwater discharge. We also show that temporal variability in the input of Fe to the sediments since the 1970s drives changes in sulfur (S) burial in the Fårö Deep, suggesting that Fe availability is the ultimate limiting factor for TA generation under anoxic conditions. The implementation of projected climate change and two nutrient load scenarios for the 21st century in BALTSEM shows that reducing nutrient loads will improve deep water oxygen conditions, but at the expense of lower surface water TA concentrations, CO2 buffering capacities and faster acidification. When these changes additionally lead to a decrease in Fe inputs to the sediment of the deep basins, anaerobic TA generation will be reduced even further, thus exacerbating acidification. This work highlights that Fe dynamics plays a key role in the release of TA from sediments where Fe sulfide formation is limited by Fe availability, as exemplified by the Baltic Sea. Moreover, it demonstrates that burial of Fe sulfides should be included in TA budgets of low-oxygen basins.

show abstract

“…Thus, the net TA flux across the SWI depends on the type and intensity of anerobic respiration, on carbonate precipitation/dissolution and whether reduced species are reoxidized by dissolved oxygen after diffusion upwards or trapped in anaerobic sediment layers by precipitation (Hu and Cai, 2011a;Krumins et al, 2013;Łukawska-Matuszewska et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Benthic alkalinity and DIC fluxes in the Rhône River prodelta generated by decoupled aerobic and anaerobic processes

Rassmann

Eitel

Cathalot

et al. 2019

Preprint

View full text Add to dashboard Cite

Abstract. Estuarine regions are generally considered a net source of atmospheric CO2 as a result of the high organic carbon (OC) mineralization rates in the water column and their sediments. Yet, the intensity of anaerobic respiration processes in the sediments tempered by the reoxidation of reduced metabolites controls the net production of alkalinity from sediments that may partially buffer the metabolic CO2 generated by OC respiration. In this study, a benthic chamber was deployed in the Rh&#244;ne River prodelta and the adjacent continental shelf (Gulf of Lions, NW Mediterranean) to assess the fluxes of total alkalinity (TA) and dissolved inorganic carbon (DIC) from the sediment. Concurrently, in situ O2 and pH microprofiles, electrochemical profiles, pore water and solid composition were measured in surface sediments to identify the main biogeochemical processes controlling the net production of alkalinity in these sediments. The benthic fluxes of TA and DIC, ranging between 14 and 74&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 and 18 and 78&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, respectively, were up to 8 times higher than the DOU fluxes (10.4&#8201;&#177;&#8201;0.9&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1) close to the river mouth, but their intensity decreased offshore, as a result of the decline in OC inputs. Low nitrate concentrations and strong pore water sulfate gradients indicated that the majority of the TA and DIC was produced by sulfate and iron reduction. Despite the complete removal of sulfate from the pore waters, dissolved sulfide concentrations were low due to the precipitation and burial of iron sulfide minerals (12.5&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1 near the river mouth), while soluble organic-Fe(III) complexes were concurrently found throughout the sediment column. The presence of organic-Fe(III) complexes together with low sulfide concentrations and high sulfate consumption suggests a dynamic system driven by the variability of the organic and inorganic particulate input originating from the river. By preventing reduced substances from being reoxidized, the precipitation and burial of iron sulfide decouples the iron and sulfur cycles from oxygen, therefore allowing a flux of alkalinity out of the sediments. In these conditions, the sediment provides a source of alkalinity to the bottom waters which mitigates the effect of the benthic DIC flux on the carbonate chemistry of coastal waters.

show abstract

Pore water alkalinity below the permanent halocline in the Gdańsk Deep (Baltic Sea) - Concentration variability and benthic fluxes

Cited by 25 publications

References 67 publications

Characterization of dredged sediments: a first guide to define potentially valuable compounds – the case of Malmfjärden Bay, Sweden

Characterization of dredged sediments: a first guide to define potentially valuable compounds – the case of Malmfjärden Bay, Sweden

Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea

Benthic alkalinity and DIC fluxes in the Rhône River prodelta generated by decoupled aerobic and anaerobic processes

Contact Info

Product

Resources

About