SEGH Articles

Sedimentary geochemistry of platinum in intertidal salt marsh sediments of the Tagus River Estuary, Lisbon, Portugal

03 December 2012
Studies of platinum in intertidal sediments have highlighted a number of features of Pt dynamics in saltmarsh environments.

 

Clara Almécija-Pereda was joint oral presentation winner at the 9th ISEG meeting held in Aveiro Portugal in July 2012. Her studies of platinum in intertidal sediments have highlighted a number of features of Pt dynamics in saltmarsh environments, an element which has rarely been studied in the estuarine environment. In December 2010 she started a PhD in Marine Biogeochemistry Group in Marine Research Institute IIM-CSIC (Spanish Research Council) in Vigo, under the supervision of Dr. Antonio Cobelo-García and Dr. Juan Santos-Echeandía and in collaboration with IPMA (Portuguese Institute of Sea and Atmosphere).

In order to better understand the role of salt mash plants in the cycle of this element, sediment cores from vegetated and non-vegetated intertidal sediments of the Tagus Estuary (Lisbon, Portugal, SW Europe), which are subject to strong anthropogenic inputs, were studied. Sediments cores, leaves, stems and roots of Sarcocornia fruticosa were collected in two salt marsh areas and analysed for their Pt concentration. Pore-water was separated from the sediments and analysed for dissolved Pt. Auxiliary parameters – dissolved oxygen, redox potential, total dissolved Mn and Fe – were also determined. Depth profiles of Pt in non-vegetated sediments showed low concentrations ranging from 0.5 to 1.0 ng g-1. Since oxygen penetration depth in these sediments is restricted to a few millimetres the observed slight enhancement with depth suggests its retention as sulphides or associated with sulphide phases. In vegetated sediments, higher levels of Pt were found in the uppermost layers (up to 3ng.g-1). This increase was found in sediment layers containing higher root biomass, suggesting that Pt retention may derived from plant activity. The atmospheric – traffic-borne – input of Pt may also contribute to the higher values in the topmost sediment layer.

Plant roots exhibited lower Pt concentrations (0.2-0.9 ng g-1) than sediments indicating that Pt is not significantly sequestered in root tissues. The oxic condition of vegetated sediments due to the plant activity may stabilize Pt in the dissolved fraction, aided by its association with dissolved organic matter derived from root exudates. Levels in the leaves and stems (0.015-0.12ng.g-1) were up to one order of magnitude lower than in roots, indicating that small amounts of Pt was translocated upward and not retained in the above ground tissues. Our results point that either S. fruticosa has low Pt phytoextraction capacity of and/or Pt is mostly present as non-bioavailable forms.

The results presented in this study were discussed in Aveiro in terms of their implications on (i) the status of Pt contamination in the Tagus Estuarine/Salt Marsh sediments due to traffic-borne emissions; (ii) the influence of redox conditions and vegetation on the geochemical sedimentary behaviour of Pt; and (iii) the uptake of Pt by vegetation.

Carla is currently (Autumn 2012) working at Dartmouth College (Hanover NH USA) as a visiting researcher and hopes to complete her PhD in Autumn 2014.

Clara Almécija-Pereda

Marine Research Institute IIM-CSIC, Vigo, Spain

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Ecological impact of the antibiotic ciprofloxacin on microbial community of aerobic activated sludge 2019-08-16

    Abstract

    This study investigated the effects and fate of the antibiotic ciprofloxacin (CIP) at environmentally relevant levels (50–500 µg/L) in activated sludge (AS) microbial communities under aerobic conditions. Exposure to 500 µg/L of CIP decreased species diversity by about 20% and significantly altered the phylogenetic structure of AS communities compared to those of control communities (no CIP exposure), while there were no significant changes upon exposure to 50 µg/L of CIP. Analysis of community composition revealed that exposure to 500 µg/L of CIP significantly reduced the relative abundance of Rhodobacteraceae and Nakamurellaceae by more than tenfold. These species frequently occur in AS communities across many full-scale wastewater treatment plants and are involved in key ecosystem functions (i.e., organic matter and nitrogen removal). Our analyses showed that 50–500 µg/L CIP was poorly removed in AS (about 20% removal), implying that the majority of CIP from AS processes may be released with either their effluents or waste sludge. We therefore strongly recommend further research on CIP residuals and/or post-treatment processes (e.g., anaerobic digestion) for waste streams that may cause ecological risks in receiving water bodies.

  • Source and background threshold values of potentially toxic elements in soils by multivariate statistics and GIS-based mapping: a high density sampling survey in the Parauapebas basin, Brazilian Amazon 2019-08-10

    Abstract

    A high-density regional-scale soil geochemical survey comprising 727 samples (one sample per each 5 × 5 km grid) was carried out in the Parauapebas sub-basin of the Brazilian Amazonia, under the Itacaiúnas Basin Geochemical Mapping and Background Project. Samples were taken from two depths at each site: surface soil, 0–20 cm and deep soil, 30–50 cm. The ground and sieved (< 75 µm) fraction was digested using aqua regia and analyzed for 51 elements by inductively coupled plasma mass spectrometry (ICPMS). All data were used here, but the principal focus was on the potential toxic elements (PTEs) and Fe and Mn to evaluate the spatial distribution patterns and to establish their geochemical background concentrations in soils. Geochemical maps as well as principal component analysis (PCA) show that the distribution patterns of the elements are very similar between surface and deep soils. The PCA, applied on clr-transformed data, identified four major associations: Fe–Ti–V–Sc–Cu–Cr–Ni (Gp-1); Zr–Hf–U–Nb–Th–Al–P–Mo–Ga (Gp-2); K–Na–Ca–Mg–Ba–Rb–Sr (Gp-3); and La–Ce–Co–Mn–Y–Zn–Cd (Gp-4). Moreover, the distribution patterns of elements varied significantly among the three major geological domains. The whole data indicate a strong imprint of local geological setting in the geochemical associations and point to a dominant geogenic origin for the analyzed elements. Copper and Fe in Gp-1 were enriched in the Carajás basin and are associated with metavolcanic rocks and banded-iron formations, respectively. However, the spatial distribution of Cu is also highly influenced by two hydrothermal mineralized copper belts. Ni–Cr in Gp-1 are highly correlated and spatially associated with mafic and ultramafic units. The Gp-2 is partially composed of high field strength elements (Zr, Hf, Nb, U, Th) that could be linked to occurrences of A-type Neoarchean granites. The Gp-3 elements are mobile elements which are commonly found in feldspars and other rock-forming minerals being liberated by chemical weathering. The background threshold values (BTV) were estimated separately for surface and deep soils using different methods. The ‘75th percentile’, which commonly used for the estimation of the quality reference values (QRVs) following the Brazilian regulation, gave more restrictive or conservative (low) BTVs, while the ‘MMAD’ was more realistic to define high BTVs that can better represent the so-called mineralized/normal background. Compared with CONAMA Resolution (No. 420/2009), the conservative BTVs of most of the toxic elements were below the prevention limits (PV), except Cu, but when the high BTVs are considered, Cu, Co, Cr and Ni exceeded the PV limits. The degree of contamination (Cdeg), based on the conservative BTVs, indicates low contamination, except in the Carajás basin, which shows many anomalies and had high contamination mainly from Cu, Cr and Ni, but this is similar between surface and deep soils indicating that the observed high anomalies are strictly related to geogenic control. This is supported when the Cdeg is calculated using the high BTVs, which indicates low contamination. This suggests that the use of only conservative BTVs for the entire region might overestimate the significance of anthropogenic contamination; thus, we suggest the use of high BTVs for effective assessment of soil contamination in this region. The methodology and results of this study may help developing strategies for geochemical mapping in other Carajás soils or in other Amazonian soils with similar characteristics.

  • Uptake of Cd, Pb, and Ni by Origanum syriacum produced in Lebanon 2019-08-06

    Abstract

    Trace metals are found naturally in soil. However, the increase in industrial and agricultural polluting activities has increased trace metal contamination and raised high concerns in the public health sector. The study was conducted on Origanum syriacum, one of the most consumed herbs in the Middle East, and was divided into three parts. (1) Pot experiment: to study the effect of Cd, Pb, or Ni levels in soil on their uptake by O. syriacum. (2) Field samples: collected from major agricultural regions in Lebanon to analyze Cd, Pb, and Ni concentrations in soil and leaves. (3) Sale outlets samples: to measure the levels of Cd, Pb, and Ni in O. syriacum tissues in the market. Results showed that there was a positive correlation between levels of Cd, Pb, and Ni in soil and those in O. syriacum tissues. None of the field samples contained Pb or Ni that exceeded the maximum allowable limits (MAL). Three samples collected from heavily poultry-manured soil contained Cd higher than the MAL. Samples collected from sale outlets did not exceed the MAL for Ni but two exceeded the MAL for Cd and one for Pb. Trace metal contamination is not a major concern in O. syriacum produced in Lebanon. Only one mixture sample from a sale outlet was higher in Pb than the MAL and three samples from heavily manured fields exceeded the MAL for Cd.