The dynamics of sediment-associated contaminants over a transition from drought to multiple flood events in a lowland UK catchment

Abstract

ArticleTitle: The dynamics of sedimentassociated contaminants over a transition from drought to multiple flood events in a lowland UK catchment It is advisable to refer to the publisher's version if you intend to cite from this work. Version: Accepted version Abstract:Fine sediment in suspended form, recently deposited overbank and in temporary storage on or in channel beds was collected in the Nene basin during a period of drought through to a period of four high flows. The sediment was analysed for arsenic, copper, lead, phosphorus and zinc concentrations with the aim of investigating their sources, movement, temporary storage and potential for environmental harm.Copper, lead and zinc probably originated from urban street dusts, phosphorus (originally in dissolved form) from sewage effluent and arsenic from natural soils developed over ironstone. There was little difference in the metal or arsenic concentrations in the sediment under different flow conditions; instead proximity to pollutant sources appeared to control their concentrations. Phosphorus in tributary sub-catchments probably adsorbed to sediment during periods of low flow but these sediments were flushed away during high flows and replaced by sediment with lower concentrations. However, concentrations of all pollutants in overbank sediments along the Nene's main channel were not reduced in successive flood events, suggesting no first flush effect. Only phosphorus accumulated on sediment at concentrations exceeding those of its catchment -based sources (e.g. street dusts, channel banks, catchment soils). This scavenging of aqueous phosphate by sediment explained the difference in behaviour between phosphorus, arsenic and heavy metals. The surface area and organic matter content were shown to have a small effect on contaminant concentrations.Street dust contaminants only exceeded predicted effect levels (PELs) in close proximity to urban areas, suggesting a small potential for harm to the aquatic environment. Arsenic concentrations exceeded PELs in most sediment samples. However, it has been shown to be largely non-bioavailable in previously published research on the Nene, limiting its potential for significant environmental harm. Phosphorus concentrations in river sediments are high in comparison to the soils in the catchment and in comparison with sediment-P concentrations in other published lowland catchment studies, indicating a large potential for eutrophication should the Phosphorus be, or become, bioavailable.2

Use of spatially distributed time-integrated sediment sampling networks and distributed fine sediment modelling to inform catchment management

“…Lamba et al, 2015;Sherriff et al, 2015). However uptake for the explicit role of detecting temporal and spatial variation in exposure to particulate pollutants is not yet widespread, despite increasing popularity (Ankers et al, 2003;Pulley et al, 2016).…”

Are source groups always appropriate when sediment fingerprinting? The direct comparison of source and sediment samples as a methodological step

“…It may therefore be optimal to use the method presented in this paper in combination with the separate examination of robust tracers with a physical basis for source discrimination, such as 137 Cs, to identify both the spatial location of sediment inputs and to confirm if inputs are from surface or subsurface sources. Pulley, Foster, and Antunes () also identified inputs of urban sediments from the town of Northampton and their subsequent downstream dilution using Pb, Cu, and Zn, as well as a lack of sediment inputs from soils over the catchment ironstone geology using arsenic, which is found in high concentrations in this geology. There is, therefore, considerable potential for the identification of contributions from easily discriminated sources using robust tracers with low associated uncertainties and a more general identification of source areas using the method presented here.…”

Developments in water quality monitoring and management in large river catchments using the Danube River as an example

“…The ICPDR Strategy for Adaptation to Climate Change (ICPDR, 2013a) predicts an increase in mean winter discharge and a decrease in mean summer discharge for the entire DRB, although there will be seasonally local variations as predicted for the Mures River (Sandu et al, 2009). The predicted increase, especially in winter floods and run-off, may increase particle transport and particle-associated water pollution, depending on the contaminants stored in the sediments and the grain sizes of the bed sediments (Pulley et al, 2016;Vignati et al, 2003). Water temperatures are also expected to increase with associated decreases in water quality (e.g.…”