Sedimentological and geochemical characterization of river suspended particulate matter (SPM) sampled by time-integrated mass flux sampler (TIMS) in the Sava River (Croatia)

Abstract

Purpose Suspended particulate matter (SPM) plays a crucial role in the transport of natural and anthropogenic substances. However, obtaining a representative sample and a substantial amount of SPM in rivers, where the flux and quantity of SPM are highly episodic, can be a challenging task. To collect a sufficient quantity of SPM for detailed sedimentological and geochemical analysis, a time-integrated mass flux sampler (TIMS) was used for the sampling in a medium size river (the Sava River, Croatia). Materials and methods Sampling was conducted in August and October 2014, and February and May 2015 under different discharge conditions. The SPM collected by TIMS was characterized with respect to its particle size distribution (PSD), mineral content, and geochemical composition. Results and discussion PSD analysis identified silt as a dominant size fraction in all samples except in May 2015 when sand prevailed; subsequent chemical dispersion of samples revealed flocculation as the main factor responsible for the resulting PSD. The mineralogical composition of the SPM was quite constant (quartz, calcite, dolomite, feldspar, illite/muscovite, kaolinite), but the contribution of particular mineral varied depending on the sampling period. In May 2015, unusually high calcite content was determined. Though the dominant source is still uncertain, a portion of calcite is likely detrital in origin. Geochemical analyses of collected material revealed significant anthropogenic input of ecotoxic elements (Ni, As, Cr, Pb, Bi, Cd, Zn, Sb) primarily associated with the fine fraction of the Sava River SPM. Conclusions A considerable amount of the SPM was collected by TIMS, both during high and low river discharge. Sedimentological analyses of the Sava River SPM suggested the input of material from various sources during different river regimes. Geochemical composition of the SPM followed its sedimentological characteristics-preferential adsorption of trace elements to fine-grained clay mineral particles was documented. Some processes inside TIMS were observed during this investigation-the suspended material captured inside the sampler underwent additional changes. The flocculation of the colloidal material instigated by algal bloom was observed.

Appraisal of geochemical composition and hydrodynamic sorting of the river suspended material: Application of time-integrated suspended sediment sampler in a medium-sized river (the Sava River catchment)

“…The upper course of river is 232 km long with drainage basin covering 12680 km 2 of surface area (Table 1). Other detailed geographical characteristics of the Sava River can be found in our previous work (Lučić et al, 2019). The Sava River has its origin as two branches, the Sava Dolinka and Sava Bohinjka rivers which flow mainly through carbonate terrain (limestone and dolostone) until their confluence at the city of Radovljica.…”

“…Nevertheless, the high content of calcite found in sediment (55%) and shallow positioned TIMS (69%) might be related to biologically mediated precipitation process (Olivier et al, 2011;Lučić et al, 2019) instigated in the summer period, which will be discussed in more later. The higher content of phyllosilicates in TIMS compared to sediments was observed in periods of lower water levels which suggests that phyllosilicates have preferential transport in surface load and have a good possibility to be retained in the sampler.…”

The impact of increased flooding occurrence on the mobility of potentially toxic elements in floodplain soil – A review

“…PTEs can be adsorbed to colloidal suspended particulate material, transported in the river water and accumulate in the floodplain soil during inundation (Du Laing et al, 2009;Frohne et al, 2011;Peijnenburg et al, 2007;Rinklebe et al, 2007). PTEs have been found to be primarily associated with fine-grained clay or silt minerals and can reside in the floodplain for longer when compared with river sediments, as they are less likely to be susceptible to erosion (Lučić et al, 2019;Malmon et al, 2002).…”

The assessment of metal contamination in water and sediments of the lowland Ilova River (Croatia) impacted by anthropogenic activities

“…TOC content was determined from lyophilised, well homogenised sediment samples using a Shimadzu SSM-5000A connected to a TOC-VCPH analyzer, by high-temperature (900 °C) catalytic (mixture of Pt/silica and CoO) oxidation method with IR detection of CO2 and calibrated with D (+) glucose (Merck, Germany) (Lučić et al 2019).…”

“…In order to gain a deeper insight in the sediment quality and possible contamination with metals, other approaches for environmental and pollution assessment should be considered besides SQGs. Therefore, contamination factors (CFs), pollution load index (PLI) and enrichment factors (EFs) were calculated to estimate and identify anomalous metal concentrations of natural origin or more commonly, to assess the anthropogenic influence on metal levels (Meybeck et al 2007;Chen et al 2014;Lučić et al 2019).…”