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@ARTICLE{Krause:887799,
      author       = {Krause, Lars and Klumpp, Erwin and Nofz, Ines and Missong,
                      Anna and Amelung, Wulf and Siebers, Nina},
      title        = {{C}olloidal iron and organic carbon control soil aggregate
                      formation and stability in arable {L}uvisols},
      journal      = {Geoderma},
      volume       = {374},
      issn         = {0016-7061},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2020-04429},
      pages        = {114421 -},
      year         = {2020},
      abstract     = {Several beneficial soil functions are linked to aggregates,
                      but how the formation and stability depend on the presence
                      of colloidal- and nanosized (1000–1 nm) bulding blocks is
                      still understood poorly. Here, we sampled subsites from an
                      arable toposequence with 190 and 340 g kg−1 clay, and
                      isolated small soil microaggregates (SMA; <20 µm) from
                      larger macroaggregate units (>250 µm) using an ultrasonic
                      dispersion energy of 60, 250, and 440 J mL−1,
                      respectively. We then allowed these small SMA to
                      reaggregated after chemical removal of organic carbon (OC)
                      as well as of Fe- and Al (hydr)oxides, respectively. The
                      size distribution of the reaggregated small SMA and fine
                      colloids (<0.45 µm) was analyzed via laser diffraction and
                      asymmetric flow field-flow fractionation coupled to
                      inductively coupled plasma mass spectrometry and organic
                      carbon detection, respectively. We found elevated amounts of
                      both finer colloids and stable SMA at subsites with higher
                      clay contents. The size distribution of small SMA was
                      composed of two distinctive fractions including colloids and
                      larger microaggregates with an average size of 5 µm. The
                      removal of Fe with Dithionite-Citrate-Bicarbonate (DCB)
                      shifted the size of the small SMA to a larger equivalent
                      diameter, while removal of OC with NaOCl reduced it. After
                      three wetting and drying cycles, the concentration of
                      colloids declined, whereas the small SMA without chemical
                      pre-treatments reaggregated to particles with larger average
                      diameters up to 10 µm, with the size depending on the clay
                      content. Intriguingly, this gain in size was more pronounced
                      after Fe removal, but it was not affected by OC removal. We
                      suggest that Fe (hydr)oxides impacts the stability of small
                      SMA primarily by being present in small-sized pores and thus
                      cementing the aggregates to smaller size. In contrast, the
                      effect of OC was restricted to the size of colloids, gluing
                      them together to small SMAs within defined size ranges when
                      OC was present but releasing these colloids when OC was
                      absent.},
      cin          = {IBG-3},
      ddc          = {910},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255)},
      pid          = {G:(DE-HGF)POF3-255},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000540257900005},
      doi          = {10.1016/j.geoderma.2020.114421},
      url          = {https://juser.fz-juelich.de/record/887799},
}