Iron concentrations are increasing in surface waters from forested headwater catchments in eastern Finland

Iron as a source of color in river waters

“…In the rivers of the present study, the TOC-to-Fe ratios were similar to those reported earlier in the boreal region (Neubauer et al, 2013;Sarkkola et al, 2013). In global rivers, the TOC flux is 4.62 × 10 14 g yr −1 and the Fe flux is 7.34 × 10 14 g yr −1 , resulting in a TOC-to-Fe ratio of 0.6 (Martin and Meybeck, 1979;Cai, 2011).…”

“…It is also a critical factor when natural water is purified to produce good-quality water for domestic and industrial purposes (Chow et al, 2007). During the past two decades over the northern hemisphere, color has increased along with the concentration of iron (Fe) and total organic carbon (TOC) (Roulet and Moore, 2006;Arvola et al, 2010;Haaland et al, 2010;Kritzberg and Ekström, 2012;Köhler et al, 2013;Sarkkola et al, 2013;Weyhenmeyer et al, 2014). The organic chromophores of TOC (referred to here as colored organic carbon, COC; see Table 1 for acronyms used; Coble, 2007;Fichot and Benner, 2011;Carter et al, 2012) and chromophores of Fe (Shapiro, 1964;Kritzberg and Ekström, 2012;Xiao et al, 2013) are important sources of color (Weyhenmeyer et al, 2014).…”

Importance of Boreal Rivers in Providing Iron to Marine Waters

“…In the Swedish systems Fe concentrations have on average doubled over four decades (1972–2010), but there is a large variation among the rivers with increases between 20 and 470%, or 1 and 28 µmol L −1 [12]. In the Finnish rivers studied by Sarkkola et al [13] Fe concentrations increased on average by 40% from 1995 to 2006. Neal et al [14] report similar trends in the Upper River Severn catchment of mid-Wales, with a doubling of Fe concentrations over 20 years.…”

Variations of total dissolved iron and its impacts during an extreme spring flooding event in the Songhua River

“…It ranked the second maximum water level and discharge ever recorded since 1960s, thus, the 2013 spring flooding event can be defined as an extreme spring flooding event (ESE) (Eisenbies et al, 2007). Various studies have reported an increase trend of dissolved iron flux during spring flooding in different boreal rivers (Pokrovsky and Schott, 2002;Andersson et al, 2006;Sarkkola et al, 2013). It was also revealed that TDFe output in the Songhua River increased significantly during the flooding events induced by the extreme rainfall events (Guan et al, 2015(Guan et al, , 2016.…”