Documentation of IFE-TIMES-Norway v2

publishedVersio

Documentation of IFE-TIMES-Norway v1

publishedVersio

Documentation of IFE-TIMES-Norway v2

publishedVersio

Data from: Widespread increases in iron concentration in European and North American freshwaters

Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends, or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28% of sites, and decreased in 4%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with organic carbon (OC) increases. Hence, Fe and OC increases may not be directly mechanistically linked, but may nevertheless be responding to common regional-scale drivers such as declining sulfur deposition or hydrological changes. A role of hydrological factors was supported by covarying trends in Fe and dissolved silica, as these elements tend to stem from similar soil depths. A positive relationship between Fe increases and conifer cover suggests that changing land-use and expanded forestry could have contributed to enhanced Fe export, although increases were also observed in non-forested areas. We conclude that the phenomenon of increasing Fe concentrations is widespread, especially in northern Europe, with potentially significant implications for wider ecosystem biogeochemistry, and for the current browning of freshwaters

Fe Trends

The data file (FeTrends.xlxs) contains data for the 340 water bodies (headwater streams, higher-order streams, lakes and river mouths) included in the Fe trends study (Björnerås et al. 2017). The data has been collected from various monitoring programs and initiatives in 10 countries and include time series of iron (Fe), organic carbon (OC), silica (Si) and sulfate (SO4) concentrations in surface waters spanning from 1990 to 2013. Catchment variables, such as catchment size and land-use, are also included in the dataset, as well as climate data (precipitation and air temperature)