Previous studies report high and increasing iron (Fe) concentrations in boreal river mouths. This Fe has shown relatively high stability to salinity-induced aggregation in estuaries. The aim of this study was to understand how the speciation of Fe affects stability over salinity gradients. For Fe to remain in suspension interactions with organic matter (OM) are fundamental and these interactions can be divided in two dominant phases: organically complexed Fe, and colloidal Fe (oxy)hydroxides, stabilized by surface interactions with OM. The stability of these two Fe phases was tested using mixing experiments with river water and artificial seawater. Fe speciation of river waters and salinity-induced aggregates was determined by synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy. The relative contribution of the two Fe phases varied widely across the sampled rivers. Moreover, we found selective removal of Fe (oxy)hydroxides by aggregation at increasing salinity, while organically complexed Fe was less affected. However, Fe-OM complexes were also found in the aggregates, illustrating that the control of Fe stability is not explained by the prevalence of the respective Fe phases alone. Factors such as colloid size and the chemical composition of the OM may also impact the behavior of Fe species.
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http://dx.doi.org/10.1021/acs.est.7b02309 | DOI Listing |
Willows (genus ) are increasingly used in operational-scale ecosystem reclamation; however, different opinions exist regarding the optimal cutting size for planting under field conditions. We compared the survival of field-planted willow cuttings sourced from upland and lowland areas with varying diameters and lengths across two growing seasons. Cuttings were grouped into 15 size classes with different diameters (0.
View Article and Find Full Text PDFEcol Lett
December 2024
Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, California, USA.
Mast seeding, the synchronous and highly variable production of seed crops by perennial plants, is a population-level phenomenon and has cascading effects in ecosystems. Mast seeding studies are typically conducted at the population/species level. Much less is known about synchrony in mast seeding between species because the necessary long-term data are rarely available.
View Article and Find Full Text PDFThis study investigates the impact of surface temperature anomalies on the health of residents within the River Niger Basin Development Authority (RIBDA) enclave, which covers Nigeria, Niger, and Mali in West Africa, with a focus on the regional implications for public health. Historical climate data from 1985 to 2014, sourced from the Climatic Research Unit Time-Series, Version 3.22 (CRU TS 3.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Department of Biology, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
Climate warming can alleviate temperature and nutrient constraints on tree growth in boreal regions, potentially enhancing boreal productivity. However, in permafrost environments, warming also disrupts the physical foundation on which trees grow, leading to leaning trees or "drunken" forests. Tree leaning might reduce radial growth, undermining potential benefits of warming.
View Article and Find Full Text PDFSci Total Environ
December 2024
Department of Geography and Environmental Management, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
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