Riverine transport of iron (Fe) and arsenic (As) is affected by their associations with natural organic matter (NOM) and suspended iron (oxy)hydroxides. Speciation has a strong influence on element transport from the headwaters to the ocean because NOM may be transported over longer distances compared to iron (oxy)hydroxides. We show that Fe speciation changes along the flow path of a boreal watercourse, as water moves from NOM-rich, acidic first-order streams with pH as low as 3.9 to less acidic higher-order systems (up to pH 6.4). Analysis by Flow Field-Flow Fractionation and chemical equilibrium modeling revealed that Fe from wetland-dominated headwaters was mainly exported as Fe-NOM complexes; in catchments with a stream order >1 and with higher pH, Fe was present in Fe-NOM complexes and precipitated as nanoparticulate iron(oxy)hydroxides which aggregated as the pH increased, with their size eventually exceeding the membrane filters cutoff (0.2 μm). The measured NOM-bound Fe decreased with increasing pH, from 0.38 to 0.16 mmol Fe·g(NOM)(-1). The high concentrations of NOM-bound Fe emphasize the importance of boreal catchments to Fe export to the oceans. Concentrations of As in the <0.2 μm fraction but larger than what is usually considered "truly dissolved" (<1000 g·mol(-1)), decreased from 75% to 26% with increasing pH. The As in this size range was mainly associated with NOM but at pH >4.5 became associated with iron(oxy)hydroxides, and its transport thus became more coupled to that of the iron(oxy)hydroxides downstream in the circumneutral streams.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/es401193j | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Residual heavy metals and antibiotic pollution in abandoned breeding areas along the northeast coast of Hainan Island, China.
Mar Pollut Bull
January 2025
Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China; CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China. Electronic address:
To assess the environmental status of an abandoned aquaculture and breeding area in the northeast coast of the Hainan Island, surface and well water, sediment and surface soils were sampled and analyzed for conventional physicochemical properties, heavy metals and antibiotics. Metagenome tests were also conducted to determine the composition and diversity of the microbial community in typical habitats. Affected by the discharge of wastewater from higher-place pond aquaculture, coastal freshwater rivers have undergone significant salinization, Cl and Na were as high as 4.
View Article and Find Full Text PDFPopulation size, income and poor sanitation interact to explain widespread streamwater contamination by antidepressants in the Metropolitan Region of São Paulo.
Environ Pollut
January 2025
Faculdade de Ciências Farmacêuticas, Universidade Estadual de Campinas. Campinas, Brazil.
The expansion of urban settlements over native environments may expose biodiversity to a host of emerging contaminants, with unintended ecological effects. This study evaluated patterns of contamination of streamwater by antidepressants in the Upper Tietê River Basin, a watershed of high social, economic and environmental relevance for comprising both the largest urban settlement in South America (the Metropolitan Region of São Paulo) and remnants of a globally important biodiversity hotspot (the Atlantic Rainforest). We sampled 53 third-order streams draining catchments regularly distributed across a gradient in urban cover.
View Article and Find Full Text PDFA matter of complexity? The role of the dorsal posterior parietal cortex in processing changes in spatial information across time.
Behav Neurosci
January 2025
Department of Psychology and Program in Neuroscience, Providence College.
The posterior parietal cortex (PPC) is an associative neocortical region that integrates multiple streams of information and is implicated in spatial cognition and decision making. In some cases, however, the PPC is not required for these functions. One possibility is that the PPC is recruited when spatial complexity is high.
View Article and Find Full Text PDFSources and Pathways of PFAS Occurrence in Water Sources: Relative Contribution of Land-Applied Biosolids in an Agricultural Dominated Watershed.
Environ Sci Technol
January 2025
Department of Agronomy, Ecological Sciences & Engineering Interdisciplinary Graduate Program, Purdue University, 915 Mitch Daniels Blvd, West Lafayette, Indiana 47907, United States.
This study evaluated PFAS occurrence in rural well water and surface water relative to land application of biosolids in a tile-drained agriculture-dominated watershed. Spatial data were used to identify potentially vulnerable rural wells based on their proximity to biosolid-permitted land and location with respect to groundwater flow. Water was collected from 103 private wells in Greater Tippecanoe County Indiana and 168 surface water locations within the Region of the Great Bend of the Wabash River watershed.
View Article and Find Full Text PDFIntegrative use of DNA barcode and morphology reveal high level of diversity in the ornamental fish on the lower Amazon basin.
PLoS One
January 2025
Undergraduate Course in Aquaculture Engineering, Federal University of Western Pará, Monte Alegre, Pará, Brazil.
The Amazon basin is the world's largest hydrographic basin, in terms of both its total area and its species diversity, with more than 2,700 species of fish. Despite this diversity, the data available on the fish fauna of the Amazon basin are still relatively scant and incomplete, in particular from the streams and floodplain lakes of the lower Amazon, which may contain a large proportion of the still undescribed species of the basin. Many of these species are expected to be of interest to the ornamental fish market.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!