Relevant Information From Microflocs

In addition to TEP and to conventional flocs, there exist discrete freshwater microflocs consisting of aggregated nanoparticles, which are likely to contribute to the growth of conventional flocs. Recently, Kerner et al.62 described the self-organization of dissolved organic matter (DOM) into micelle-like microparticles (0.4 to 0.8 ¡m) in river water (Elbe River, Germany). This abiotic transfer of dissolved organic carbon to microparticles has great ecological significance because it occurs without carbon loss, while depending only on temperature and the aggregation capacity of the DOM molecules involved. For the characterization of DOM molecules, the analytical chemical technology continues to evolve well.63

In earlier work on heterogeneous microparticles in river water samples (Rhine River, near Basle, Switzerland), Filella et al.64 demonstrated the capture of nano-scale mineral particles at the surfaces of suspended meshworks of long organic fibrils whose diameters were in the lowest part of the nanoscale range. This discovery led to a focus on colloidal organic fibrils30 as bridging structures and as accumulators of nanoscale mineral coatings; these flocculation events provided an impetus for the development of analytical electron microscopy (AEM) for addressing the need to characterize the nanoscale components of microflocs initially,65-67 and then of large flocs.14 The research on microfloc nanocomponents and their biogeochemical roles were done in the following natural ecosystems: Lake Lugano, Switzerland;66 Paul Lake, MI, USA;66,67 and the peatlands of the Bied River, Switzerland.65,66 The research thrust on fibril/mineral colloid aggregation accompanied an earlier, ongoing, microbiology-based thrust which focused on biomineralization initiated at the nanoscale on biological surfaces.68 Such nanoscale studies have great relevance to the transformations of metals within flocs10 and within consolidated sediments.69

0 0

Post a comment