scholarly journals The distribution of Cd and Cu in sediments covered with algal mat

2013 ◽  
Vol 9 (3) ◽  
pp. 243-250
Keyword(s):  
Organic Compounds ◽  
Sediment Cores ◽  
Seasonal Fluctuation ◽  
Bcr Sequential Extraction ◽  
Algal Mats ◽  
Fe Oxides ◽  
Coastal Marine ◽  
Sequential Extraction Method ◽  
Seasonal Basis ◽  
Algal Mat

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible to observe the presence of organosedimentary structures that are commonly flat and laminar in shape. These structures are called algal mats or recent stromatolites due to their remarkable similarities to fossil stromatolites. The aim of this work was the study of the distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a closed bay at Anavissos, on the coast of Saronikos Gulf. Small sediment cores were collected from one point inside the cove on a seasonal basis and the trace metals extracted according to the BCR sequential extraction method. The main results of the study were: Most of the labile Cd was associated with small inorganic grains or lime particles. The contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to organic compounds and sulfides. The high contribution of the labile Cd to the total element (over 85%) was a strong indication of anthropogenic origin. On the other hand, most of the Cu in the sediment was associated with the crystal lattice (74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated with organic compounds and sulfides whereas the less abundant form was that associated with Mn and Fe oxides. On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu were normal for the region.

Current Velocity in Streams and the Composition of Benthic Algal Mats

1986 ◽  
Vol 43 (6) ◽  
pp. 1156-1162 ◽  
Author(s):  
Michael A. Reiter ◽  
Robert E. Carlson
Keyword(s):  
Current Velocity ◽  
Free Water ◽  
Open Water ◽  
Dry Weight ◽  
Taxonomic Diversity ◽  
Taxonomic Composition ◽  
Water Velocity ◽  
Algal Mats ◽  
Laboratory Flume ◽  
Algal Mat

Water velocity is commonly accepted as a factor in the development of benthic algal mats in streams. Within a stream, two different zones of velocity are observed: the free-water velocity of the open water and the local velocity near the stream substrate. A closed laboratory flume system was used to observe the taxonomic composition of benthic algal mats and corresponding changes in the local velocities under different free-water velocities. As the algal mat developed under each experimental velocity, local velocities diminished and eventually became equal in all sections, while free-water velocities remained different. After a period of maximum taxonomic diversity during the first 2 wk of mat development, taxonomic composition, relative abundance of the taxa, and dry weight biomass became increasingly similar in the three velocity regimes, although the mats appeared different upon casual observation. Differences in composition and morphology in natural algal mats may not result from differences in current velocity, and the idea of a "closed monolayer" algal mat may not be appropriate in all situations.

Speciation Analysis of Harmful Elements in the Scheelite Tailings

2014 ◽  
Vol 1065-1069 ◽  
pp. 3096-3099
Author(s):  
Zi Qiang Gu ◽  
Xu Qing Liu ◽  
Ke Xiang ◽  
Xuan Qin ◽  
Ya Yun Li
Keyword(s):  
European Union ◽  
Extraction Method ◽  
Speciation Analysis ◽  
Bcr Sequential Extraction ◽  
Comprehensive Utilization ◽  
Extraction Fraction ◽  
Lead And Zinc ◽  
Normal Environment ◽  
Sequential Extraction Method ◽  
Lead Zinc

The speciations of lead, zinc, arsenic from the skarn type scheelite flotation tailings of a Hubei Mining Co., Ltd were analysized on the ICP-AES spectroscopy, while the samples were prepared with the BCR three step extraction method proposed by the Standard Bureau of European Union and the improved BCR sequential extraction method proposed by Rauret.The results showed that: (1) The contents of arsenic, lead and zinc existing in Stable residual state, are 66.23%、41.44% and 36.34%, respectively, and the harmful elements in the tailings are basically stable under the normal environment conditions; (2)Lead in the exchangeable speciation with better activity occupies 24.61%,and the exchangeable speciation would be released out through the purification treatment of mineral processing wastewater and the placement clarification of the tailings to improve the rate of the residue state and to ensure the safety of comprehensive utilization of tailings; (3)Zinc in the oxidizable extraction fraction amounts to 40.30%, and the comprehensive utilization of tailings should prevent the release of zinc under the strong oxidizing conditions.

The role of wetlands as environmental buffers: comparison of phosphorus retention capacity between hydrosedimentary environments

2020 ◽  
Author(s):  
Jaume Company ◽  
Raquel Vaquer-Sunyer ◽  
Julián García-Comendador ◽  
Josep Fortesa ◽  
Aleix Calsamiglia ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Marine Ecosystems ◽  
Organic P ◽  
Retention Capacity ◽  
Inorganic P ◽  
Depositional Processes ◽  
Coastal Marine ◽  
Accretion Rates ◽  
Coastal Marine Ecosystems ◽  
Artificial Channel

<p>Since the middle of the twentieth century, human societies has quadrupled the environmental flow of phosphorus –P, dramatically impairing freshwater and coastal marine ecosystems (1). Wetlands act as environmental buffers retaining nutrients and pollutants delivered from upstream parts of river systems. This buffer effect also avoids the conveyance of these pollutants to the marine environment preventing eutrophication of coastal marine ecosystems.</p><p>The aim of this research is to assessing P concentrations within the S’Albufera (1,708 ha), the main wetland of Mallorca (Spain) and protected by the Ramsar list of wetlands of international importance. Since the middle of the ninetieth century, it is an artificial system, in which waters are forced to take the shortest route to the sea (2). The study of accretion rates by using <sup>137</sup>Cs measurements will be combined with the nutrient retention capacity analysing phosphorus concentrations in fine-grained sediments. Accordingly, 5 integrated sediment cores, composed by two replicas, sectioned at 5-cm intervals were collected in February 2016 in three representative hydrosedimentary environments of S’Albufera: two at the centre of the main artificial channel, one at the bank of this main channel and two within the lagoon areas. Total, inorganic and organic P were quantified in 532 samples in order to assess the nutrient dynamics into these representative hydrosedimentary environments and depths.</p><p>The <sup>137</sup>Cs measurements depicted how the sediment cores collected in the middle of the artificial channel as well into its banks were mainly characterized by erosional processes due to the lack of <sup>137</sup>Cs at any depth. On the other side, cores sampled at lagoon areas illustrated depositional processes with mean accretion rates since 1963 between ca. 0.139 g m<sup>-2 </sup>yr<sup>-1 </sup>to 0.169 g m<sup>-2</sup> yr<sup>-1</sup>.</p><p>Total P concentrations were significantly higher in lagoon areas (0.082 mg P g<sup>-1</sup> sediment) than in the sediment from banks of the main artificial channel (0.037 mg P g<sup>-1</sup> sediment) or into the middle of this channel (0.03 mg P g<sup>-1</sup> sediment). The same pattern was observed for organic and inorganic P with concentrations within lagoon areas of 0.039 mg P g<sup>-1</sup> sediment and 0.043 mg P g<sup>-1</sup> sediment, respectively. Concentrations for the banks of the main artificial channel were 0.018 mg P g<sup>-1</sup> sediment for inorganic P and 0.019 mg P g<sup>-1</sup> sediment for organic P. At the middle of the artificial channel, concentrations were even lower, with 0.014 mg P g<sup>-1</sup> sediment for inorganic P and 0.016 mg P g<sup>-1</sup> sediment for organic P.</p><p>These results elucidate that the natural maintenance of wetlands is crucial to ensure their optimal functioning as environmental buffers.</p><p> </p><p>References</p><p>(1) Lane and Autrey, 2017. MFR. DOI: 10.1071/MF16372</p><p>(2) Lopez et al., 1996. ECSS. DOI: 10.1006/ecss.1996.0014</p><p>This work was supported by the research project CGL2017-88200-R “Functional hydrological and sediment connectivity at Mediterranean catchments: global change scenarios –MEDhyCON2” funded by the Spanish Ministry of Science, Innovation and Universities, the Spanish Agency of Research (AEI) and the European Regional Development Funds (ERDF).</p><p> </p><p> </p>

Sequential Extraction of Vanadium in Different Soil Samples Using Conventional and Ultrasonic Devices

2013 ◽  
Vol 96 (3) ◽  
pp. 650-656 ◽  
Author(s):  
Sumaira Khan ◽  
Tasneem Gul Kazi ◽  
Nida Fatima Kolachi ◽  
Imran Afridi ◽  
Naeem Ullah
Keyword(s):  
Sequential Extraction ◽  
Thermal Power ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Total Content ◽  
Standard Addition ◽  
Absorption Spectrometry ◽  
Soil Samples ◽  
Bcr Sequential Extraction ◽  
Sequential Extraction Method ◽  
Agricultural Areas

Abstract A rapid ultrasound accelerated sequential extraction (USE) procedure was used to develop chemical partitioning of vanadium (V), proposed by the Community Bureau of Reference/European Union Measurement and Testing Programme (BCR). The effects of ultrasonic treatment on the extraction of V in different soil samples collected from the vicinity of a thermal power plant and agricultural areas of Sindh, Pakistan, were evaluated. In the conventional BCR-sequential extraction method, each extraction step takes 16 h. With the use of ultrasound energy, Steps 1–3 of the USE procedure (excluding the hydrogen peroxide digestion in Step 3, which was performed conventionally) could be completed in 45, 40, and 45 min, respectively. Analysis of the extracts was performed by electrothermal atomic absorption spectrometry. The total contents of V were obtained by digestion with two acid mixtures: H2O2–HF–HNO3–H2SO4 and HClO4–HF–HNO3–H2SO4. Validation was performed by the standard addition technique. Results obtained for each fraction by both methods were statistically compared; no significant differences were found (P < 0.05). The accuracy of the USE procedure was checked by comparing the sum of the V contents in the three fractions and residue with the total content of V. The results of this work provide information on the chemical composition, distribution, and potential mobility of the V in different soils.

scholarly journals Marine sediment cores database for the Mediterranean Basin: a tool for past climatic and environmental studies

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
I. Alberico ◽  
I. Giliberti ◽  
D.D. Insinga ◽  
P. Petrosino ◽  
M. Vallefuoco ◽  
...  
Keyword(s):  
Marine Sediment ◽  
Mediterranean Basin ◽  
Sediment Cores ◽  
National Research Council ◽  
Past Research ◽  
Calcareous Nannoplankton ◽  
Coastal Marine ◽  
Scientific Papers ◽  
The Mediterranean ◽  
The Mediterranean Basin

AbstractPaleoclimatic data are essential for fingerprinting the climate of the earth before the advent of modern recording instruments. They enable us to recognize past climatic events and predict future trends. Within this framework, a conceptual and logical model was drawn to physically implement a paleoclimatic database named WDB-Paleo that includes the paleoclimatic proxies data of marine sediment cores of the Mediterranean Basin. Twenty entities were defined to record four main categories of data: a) the features of oceanographic cruises and cores (metadata); b) the presence/absence of paleoclimatic proxies pulled from about 200 scientific papers; c) the quantitative analysis of planktonic and benthonic foraminifera, pollen, calcareous nannoplankton, magnetic susceptibility, stable isotopes, radionuclides values of about 14 cores recovered by Institute for Coastal Marine Environment (IAMC) of Italian National Research Council (CNR) in the framework of several past research projects; d) specific entities recording quantitative data on

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