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

  • Exposure to respirable and fine dust particle over North-Central India: chemical characterization, source interpretation, and health risk analysis 2019-12-10

    Abstract

    This study enhances the understanding of the particulate matters (PM2.5 and PM10) and their physical and chemical behavior over the Taj Mahal, Agra, in North-Central India. The mass concentration was determined, and the shape and size of the particles and chemical characterizations have been carried out using SEM–EDX. The high level and significant variation of PM10 (162.2 µg m−3) and PM2.5 (83.9 µg m−3) were observed. The exceedance factor of the present study region is in critical and moderate condition. Morphological characterization reveals the particles of different shapes and sizes, while elemental analysis shows the presence of Si, Al, Fe, Ca, K, Cl, Mg, Na, Cu, and Zn. The dominance of Si indicated the contribution of natural sources, i.e., soil over this region. Three significant sources, viz. soil/road paved dust/vegetative emissions, vehicular/industrial emissions, and intermingling of dust and combustion particles, have been identified using principal component analysis over North-Central India. Health risk analysis of particulate matter identified carcinogenic and non-carcinogenic metals in the present study, which comes in contact with human beings during inhalation. The non-carcinogenic risk was much higher than the acceptable level. The high carcinogenic risks were found in Zn in PM10 and Cu in PM2.5 for both children and adults.

  • Integration of remote sensing data and in situ measurements to monitor the water quality of the Ismailia Canal, Nile Delta, Egypt 2019-12-10

    Abstract

    The Ismailia Canal is one of the most important tributaries of the River Nile in Egypt. It is threatened by extinction from several sources of pollution, in addition to the intersection and nearness of the canal path with the Bilbayes drain and the effluent from the two largest conventional wastewater treatment plants in Greater Cairo. In this study, the integration of remote sensing and geospatial information system techniques is carried out to enhance the contribution of satellite data in water quality management in the Ismailia Canal. A Landsat-8 operational land imager image dated 2018 was used to detect the land use and land cover changes in the area of study, in addition to retrieving various spectral band ratios. Statistical correlations were applied among the extracted band ratios and the measured in situ water quality parameters. The most appropriate spectral band ratios were extracted from the NIR band (near infrared/blue), which showed a significant correlation with eight water quality metrics (CO3, BOD5, COD, TSS, TDS, Cl, NH4, and fecal coliform bacteria). A linear regression model was then established to predict information about these important water quality parameters along Ismailia Canal. The developed models, using linear regression equations for this study, give a set of powerful decision support frameworks with statistical tools to provide comprehensive, integrated views of surface water quality information under similar circumstances.

  • Geophagy among East African Chimpanzees: consumed soils provide protection from plant secondary compounds and bioavailable iron 2019-12-01

    Abstract

    Geophagy, the intentional consumption of earth materials, has been recorded in humans and other animals. It has been hypothesized that geophagy is an adaptive behavior, and that clay minerals commonly found in eaten soil can provide protection from toxins and/or supplement micronutrients. To test these hypotheses, we monitored chimpanzee geophagy using camera traps in four permanent sites at the Budongo Forest Reserve, Uganda, from October 2015–October 2016. We also collected plants, and soil chimpanzees were observed eating. We analyzed 10 plant and 45 soil samples to characterize geophagic behavior and geophagic soil and determine (1) whether micronutrients are available from the soil under physiological conditions and if iron is bioavailable, (2) the concentration of phenolic compounds in plants, and (3) if consumed soils are able to adsorb these phenolics. Chimpanzees ate soil and drank clay-infused water containing 1:1 and 2:1 clay minerals and > 30% sand. Under physiological conditions, the soils released calcium, iron, and magnesium. In vitro Caco-2 experiments found that five times more iron was bioavailable from three of four soil samples found at the base of trees. Plant samples contained approximately 60 μg/mg gallic acid equivalent. Soil from one site contained 10 times more 2:1 clay minerals, which were better at removing phenolics present in their diet. We suggest that geophagy may provide bioavailable iron and protection from phenolics, which have increased in plants over the last 20 years. In summary, geophagy within the Sonso community is multifunctional and may be an important self-medicative behavior.