Marcel van der Perk

We performed a series of tracer experiments in large outdoor flumes at the Quesnel River Research Centre, Likely, BC, Canada to quantify the hyporheic transit time distribution in gravel bed sediments. For this purpose, an 18.9 m x 2 m flume was filled with a 30 cm thick layer of well-sorted gravel with a d50 of 39.1 mm. The average longitudinal gradient of the gravel bed was 0.05% The flumes were filled with aerated local groundwater, so that a standing water layer of 20 cm depth over the gravel bed was established. Subsequently, dissolved common salt until the water reached an electrical conductivity (EC) between 450 and 550 µS/cm. The flumes were equilibrated overnight to ensure a uniform distribution of the salt concentration across the flume. At the start of each experiment local groundwater (EC = 150µS/cm) was discharged at a rate of approximately 16 l/s at the upper end of the flume. At 10 m downstream from the inlet the EC was monitored in the water layer until the EC remain...

Climate change is projected to significantly affect the concentrations and mobility of contaminants, such as metals and pathogens, in soil, groundwater and surface water. Climate- and land management-induced changes in soil organic carbon and dissolved organic carbon levels may promote the transport of toxic substances, such as copper and cadmium, and pathogenic microorganisms, ultimately affecting the exposure of humans and ecosystems to these contaminants. In this study, we adopted the Century model to simulate past (1900 - 2010), present, and future (2010 - 2100) SOC and DOC levels for a sandy and a loamy soil typical for Central and Western European conditions under three land use types (forest, grassland and arable land) and several future scenarios addressing climate change and land management change. The climate scenarios were based on the KNMI'06 G+ and W+ scenarios from the Royal Dutch Meteorological Institute. The simulated current SOC levels were compared to observed ...

Copper fungicides, for example Bordeaux mixture, are frequently used in vineyards to protect young grapes against mildew. The copper accumulates in the topsoil layer where it is absorbed to clay minerals and soil organic matter. Part of the copper may be transported across the vineyard by surface runoff and soil erosion, which could then enter the fluvial system. To investigate the transport and retention of copper in vineyards, detailed mapping of both the lateral and vertical spatial distribution of copper in vineyard soils was performed in two vineyards located in the Ouveze catchment in southeastern France. The vertical distributions of copper concentrations over the soil profile, and the spatial distribution patterns of copper deposition densities enabled us to identify and assess the redistribution mechanisms and transfer rates of sediment-associated copper within the vineyard fields.

... a coarser GSD at peak discharge lasts longer than the period in which the water level in the river channel overtops the minor dike. ... We also thank Yogesh Agrawal (Sequoia Scientific) for his help with the data analyses and the anonymous reviewer for his suggestions to improve ...

<p>To predict the transfer and fate of metal contaminants in river systems, a thorough understanding of the factors controlling metal concentrations is essential. This study examines the variability and covariability of dissolved and particulate metal concentrations in the Rhine River at the Lobith monitoring station in the Netherlands in the period 2009 -2017. The data analysis concentrated on copper and zinc as these metals were not affected by limits of detection. The total copper and zinc concentrations are significantly linearly related to the suspended sediment concentrations. The intercept of this relation represents the mean dissolved metal concentration and the gradient the mean particulate metal concentrations. The thus estimated mean dissolved and particulate concentrations of zinc and copper resemble mean measured concentrations. For both metals, the particulate concentrations are only weakly positively correlated to the dissolved concentrations. This correlation can be attributed to the fact that both the dissolved and the particulate concentrations of copper and zinc are negatively related to river discharge, where the decline of the particulate concentrations in response to increasing discharge is relatively larger than that of the dissolved concentrations. When the particulate metal concentrations are standardised for the diluting effect of discharge, the standardised particulate metal concentrations do not correlate significantly with the dissolved concentrations. This may indicate that the sediment solid/liquid partition coefficients (Kd-values) for the considered metals vary considerably in time, although this hypothesis requires further investigation.</p>

Purpose Information on the geochemical composition of suspended sediments in rivers is crucial to identify sediment source type or area. In large river basins, however, the relation between sediment composition and its controlling factors is often obscured. This study aims to assess and improve the conceptual understanding on the factors and mechanisms that control the composition of suspended sediments in the River Rhine, one of the large European rivers, and to identify the dominant source types of elements. Materials and methods We performed log-linear regression analysis and principal component analysis (PCA) on bi-weekly monitoring data of suspended sediment composition, supplemented with daily measurements of suspended sediment concentrations (SSC) and discharge at the Lobith monitoring station near the German-Dutch border for the period 2011–2016. Results and discussion The statistical analyses show a consistent grouping of elements that display contrasting temporal variation...

Many deltas are threatened by accelerated soil subsidence, sea level rise, increasing river discharge, and sediment starvation. Effective delta restoration and effective river management require a thorough understanding of the mechanisms of aggradation, erosion, and their controls. Sediment dynamics has been studied at floodplains and marshes, but little is known about the sediment dynamics and budget of newly created wetlands. Here we take advantage of a recently opened tidal freshwater system to study both the mechanisms and controls of aggradation and erosion in newly created wetlands. We quantified both the magnitude and spatial patterns of aggradation and erosion in a former polder area in which water and sediment have been reintroduced since 2008. Based on terrestrial and bathymetric elevation data, supplemented with field observations of the location and height of cut banks and the thickness of the newly deposited layer of sediment, we determined the sediment budget of the st...

This study investigates the impact of future climate change on heavy metal (i.e., Cd and Zn) transport from soils to surface waters in a contaminated lowland catchment. The WALRUS hydrological model is employed in a semi-distributed manner to simulate current and future hydrological fluxes in the Dommel catchment in the Netherlands. The model is forced with climate change projections and the simulated fluxes are used as input to a metal transport model that simulates heavy metal concentrations and loads in quickflow and baseflow pathways. Metal transport is simulated under baseline climate ("2000-2010") and future climate ("2090-2099") conditions including scenarios for no climate change and climate change. The outcomes show an increase in Cd and Zn loads and the mean flux-weighted Cd and Zn concentrations in the discharged runoff, which is attributed to breakthrough of heavy metals from the soil system. Due to climate change, runoff enhances and leaching is acce...

ABSTRACT Transient storage of fine sediments in the river bed determines the fine sediment residence time in gravel bed streams at intermediate time scales between days and a few years. We measured the sediment infiltration into the gravel bed at two locations in the Geul River, the Netherlands (mean discharge = 2 m3 s-1) using two methods: 1) a gravimetric method and 2) a metal concentration-based method. Both methods involved the placement of sediment traps, consisting of cylindrical mesh cages with a diameter of 15 cm and a height of 10 cm, in the gravel bed. In the first method, the cage was filled with clean gravel greater than 12.5 mm (the size of the mesh openings) collected from the local river bed (D50 ? 19 mm). In the second method, the sediment traps were filled with clean gravel and about 700 grams of fine sand. During the sampling period, this 'clean' sand was contaminated by deposition of metal-contaminated fine sediment from the Geul River. After four to eight days, the sediment traps were removed. A bag around the cage, which had been lowered during sampling, prevented the fine sediment to wash out from the sediment traps during removal. The fine sediment was washed from the sediment traps and subsequently dried and weighed. For the second method, the zinc concentrations of the fine sand and the fine sediment collected from the sediment traps were measured using a Thermo Fisher Scientific Niton® handheld XRF analyser. The sediment infiltration or deposition rates were then calculated from the differences between the zinc concentrations in the sediment samples and the 'clean' sand. The fine sediment deposition rates measured using the concentration-based method (0.49 ± 0.20 kg m-2 d-1 [mean ± 1 st. dev. ]) were consistent with those measured using the gravimetric method (0.54 ± 0.22 kg m-2 d-1). The mean and variation of the fine sediment deposition rates increased with stream discharge during the sampling period. The corresponding vertical mass fluxes in a 1 km long river reach are on the same order of magnitude as the longitudinal suspended sediment flux of the Geul River. This means that sediment infiltration into the gravel bed comprises a substantial portion of the sediment budget of the Geul River.

In 2002-2004 we undertook six sampling campaigns during representative hydrological stages in a 901 km 2 Estonian lowland catchment to quantify the spatial and seasonal variability of in-stream Dissolved Inorganic Nitrogen (DIN) and Dissolved Reactive Phosphorus (DRP) concentrations and to identify the influence of land cover and landscape structure. Using a synoptic approach we mapped concentrations in all stream orders.

... Drainage levels were taken from the data on winter drainage levels provided by the local water board. A good match between the minimum elevation minus 0.60 m and the drainage level was found which provided a check on the data obtained from the water board. ...

... MI Balanov, P. Strand and BJ Howard, Contribution of fungi to radiocaesium intake by ... 6. JP Absolom, SD Young and NMJ Crout, Radio-caesium fixation dynamics: measurement in six ... U. Sansone, O. Voitsekhovitch (Eds.), Modelling and Study of the Mechanisms of the Transfer ...