Fractionation of organic C, nutrients, metals and bacteria in peat porewater and ice after freezing and thawing

Morgalev, Sergey; Lim, Artem G.; Morgaleva, Tamara; Morgalev, Yuri N.; Manasypov, Rinat M.; Kuzmina, Daria; Shirokova, Liudmila S.; Orgogozo, Laurent; Loiko, Sergey V.; Pokrovsky, Oleg S.

doi:10.1007/s11356-022-22219-1

Cited by 5 publications

(3 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Contrasting to these soluble and labile solutes were divalent metals and insoluble TE 3+ and TE 4+ trace elements, which are known to be carried in the form of organic and organo-mineral (Fe, Al) colloids in the peat porewater (i.e., [15]) and dispersed ice of the peat cores [10]. Therefore, in agreement with previous studies of experimental bi-directional freezing of the entire peat cores (i.e., [44,45]), we hypothesize that, during freezing front propagation, large size organic-Fe-Al colloids are subjected to preferential exclusion relative to truly dissolved (inorganic) solutes from the ice. As a result, they could form precipitates either in the bulk of the remaining fluid or at the actual interface between the forming ice and the remaining aqueous solution.…”

Section: Discussionsupporting

confidence: 90%

“…Some decrease in DOM between the initial leachate and final fluid, after full freezing and thawing, is most likely linked to coagulation, precipitation, and removal (on filters) in the form of amorphous organic-rich solid phases. The detailed molecular mechanisms of this freeze-induced coagulation of ionic solutes and colloids are not known [35,45,46]. The chemical nature of coagulated material has not been investigated in the present study, but most likely includes, in addition to organic humic particles (e.g., [67]), organo-mineral composites of Fe and Al (hydr)oxides tightly linked to organic matter (OM).…”

Section: Discussionmentioning

confidence: 96%

“…Although laboratory experiments allow for the identification of governing factors during freezing/thawing effects [36][37][38][39][40][41][42][43], their applications to naturally relevant aquatic settings of high latitude permafrost peatlands remain very restricted. Previous works in permafrost peatlands reported translocation of microorganisms and changes in porewater chemistry (pH, UV absorbance, DOC, major and trace element concentrations) after the thawing and bidirectional freezing of peat cores [44,45]. Another recent study examined the impact of freezing/thawing cycles (FTC) on the surface waters from Northeast European permafrost peatland [46].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Partitioning of Dissolved Organic Carbon, Major Elements, and Trace Metals during Laboratory Freezing of Organic Leachates from Permafrost Peatlands

et al. 2023

Self Cite

View full text Add to dashboard Cite

Climate change is likely to modify the freezing–thawing cycles in soils and surface waters of permafrost-affected and subarctic regions. However, the change of solution chemical composition during ice formation and the evolution of the remaining fluids remain very poorly known. Towards a better understanding of dissolved (<0.45 µm) organic carbon, as well as major and trace element behavior in permafrost peatland environments, here we performed laboratory freezing of peat leachates, from complete freezing to complete thawing, in order to quantify the partitioning of solutes between the aqueous solution and the remaining ice. Freezing experiments were conducted, with and without polyurethane insulation. Two main types of experiments involved (i) progressive freezing, when we started from liquid leachates (filtered <0.45 µm) and allowed them to freeze at −18 °C, and (ii) progressive thawing, where first, we froze solid a series of <0.45 µm filtered leachates and then monitored their thawing at room temperature, 20 °C. We hypothesized the existence of two main groups of solutes, behaving conservatively or non-conservatively during freezing, depending on their incorporation into the ice or their ability to coagulate in the form of insoluble minerals or amorphous materials in the fluid phase. An unexpected result of this work was that, despite a sizable degree of element concentration in the remaining fluid and possible coagulation of organic, organo-mineral, and inorganic compounds, the freezing and subsequent thawing produced final concentrations of most solutes which were not drastically different from the initial concentrations in the original leachates prior to freezing. This demonstrates the high stability of dissolved (<0.45 µm) organic carbon, iron, aluminum, and some trace metals to the repetitive freezing and thawing of surface waters in permafrost peatlands.

show abstract