Environmental Geochemistry (Environmental Studies)
Download (.pdf) The effect of adsorbed lipid on pyrite oxidation under biotic conditions
Jun Hao, Curtis Cleveland, Eelin Lim, Daniel R Strongin, Martin AA Schoonen Geochemical Transactions 2006, 7:8 (25 July 2006)
doi:10.1186/1467-4866-7-8
The chemolithoautotrophic bacterium, Acidithiobacillus ferrooxidans, commonly occurs in acid mine drainage (AMD)... more The chemolithoautotrophic bacterium, Acidithiobacillus ferrooxidans, commonly occurs in acid mine drainage (AMD) environments where it is responsible for catalyzing the oxidation of pyrite and concomitant development of acidic conditions. This investigation reports on the growth of this bacterial species on the pyrite surface and in the aqueous phase at a pH close to 2 as well as the role of adsorbed lipid in preventing pyrite dissolution. Both acid washed pyrite and acid-washed pyrite coated with lipids were used as substrates in the studies. The choice of lipid, 1,2-bis(10,12-tricosadiynoyl)-sn-Glycero-3-Phosphocholine lipid (23:2 Diyne PC), a phosphocholine lipid, was based on earlier work that showed that this lipid inhibits the abiotic oxidation rate of pyrite. Atomic force microscopy showed that under the experimental conditions used in this study, the lipid formed ~4–20 nm layers on the mineral surface. Surface-bound lipid greatly suppresses the oxidation process catalyzed by A. ferrooxidans. This suppression continued for the duration of the experiments (25 days maximum). Analysis of the bacterial population on the pyrite surface and in solution over the course of the experiments suggested that the pyrite oxidation was dependent in large part on the fraction of bacteria bound to the pyrite surface.
Enregistrement des variations climatiques au cours des interglaciaires d'après l'étude des isotopes stables de la calcite de tufs pléistocène du nord de la France : exemple des séquences de Caours (SIM 5e; Somme) et La-Celle-sur-Seine (MIS 11 ; Seine-et-Marne)
Co-authored with N. Limondin-Lozouet, P. Antoine, A. Marca-Bell and J. Andrews.
Published in Quaternaire, 22 (4), 2011
RECORD OF CLIMATIC CHANGES DURING INTERGLACIALS FROM STABLE ISOTOPES IN NORTHERN FRANCE PLEISTOCENE TUFA CALCITE:... more
RECORD OF CLIMATIC CHANGES DURING INTERGLACIALS FROM STABLE ISOTOPES IN NORTHERN FRANCE PLEISTOCENE TUFA CALCITE: EXAMPLES OF CAOURS (MIS 5e; SOMME) AND LA CELLE (MIS 11; SEINE ET MARNE).
Tufas are mainly composed of calcite (CaCO3) which makes them suitable for geochemical investigation, especially oxygen and carbon stable isotopes (δ18O and δ13C). These isotopic parameters have already been shown to record temperature and humidity variations in the Holocene tufas, proving their suitability as climatic proxies. This study focuses on two French Pleistocene sites, Caours and La Celle. Results are compared to palaeoenvironmental, especially malacological, data. This comparison shows that δ18O and δ13C in tufas are important proxies of palaeoclimatic variation during Pleistocene interglacials, just as they are during the Holocene.
La composition minéralogique des tufs calcaires, essentiellement constitués de CaCO3, permet l’utilisation d’indicateurs climatiques géochimiques et en particulier l’étude des isotopes stables de l’oxygène et du carbone (δ18O et δ13C). Ces derniers sont déjà bien connus dans les tufs holocènes comme marqueurs des variations de température et d’humidité. L’analyse des isotopes stables a été réalisée ici sur les séquences de tuf pléistocènes de Caours (SIM 5e, Somme) et de La Celle (SIM 11, Seine et Marne). Les résultats de cette étude géochimique ont été comparés aux données paléoenvironnementales, notamment malacologiques. Ces premières analyses montrent que, comme dans le cas des tufs holocènes, les variations des isotopes stables du carbone et de l’oxygène dans les tufs pléistocènes constituent des indicateurs fiables des variations climatiques au cours des interglaciaires pléistocènes.
Evaluation of the CR(VI) and other toxic element contamination and their potential sources: The case of the Thiva basin (Greece)
M. Economou-Eliopoulos*, D. Antivachi, Ch. Vasilatos and Megremi, I., 2011. in Geoscience Frontiers, Elsevier, DOI: 10.1016/j.gsf.2011.11.010
Αn integrated approach was performed on the soil, plant-crops and groundwater system at the Thiva basin, to evaluate... more
Αn integrated approach was performed on the soil, plant-crops and groundwater system at the Thiva basin, to evaluate the extent and intensity of the heavy metal contamination, the percentage of metals transferred into plants/crops (bio-accumulation) and the potential sources of contamination.
Heavy metal contents (230 to 310 Cr, 1200 to 2200 Ni, 50 to 80 Co, 880 to 1150 Mn and 44500 to 66200 Fe (all in ppm) in the Thiva soils are higher than those in the Assopos basin. An increasing trend in the heavy metal contents, from the Assopos to the Thiva basin (Mouriki), indicates that the metal source are probably the Ni-laterites and ophiolites, located towards north. On the other hand, groundwater samples from domestic and irrigation wells throughout the Thiva basin exhibit relatively low (8 to 37 ppb) concentrations in Cr compared to the Assopos (up to 150ppb). The plots of Cr versus Mg/Ca, Mg/Na versus Ca/Na, B versus Si/(Si+Na) and Mg/Si versus Ca/Si ratios revealed a low degree of salinization in the Thiva compared to that the Assopos (Avlida) basin. Such diversity between the soil and groundwater distribution of chromium, coupled with the lack of any systematic relationship between Mg and Cr concentration in water point to a major contribution to the Cr contamination of the aquifer from anthropogenic activities and to a lesser extent by natural processes. The average Cr contents (dry weight) ranges from 1.7 to 4.6 ppm (average 2.2) in carrots, potatoes and onions. The percentage of soil metals Crtotal, Cr(VI), Ni, Mn and Fe ranges between 0.06 and 3.2 (average 0.53±0.4), whilst that for Cu and Zn ranges from 16 to 81 (average 36±24). The Cr transfer to plants is low, due to the high resistance of chromite (main host of Cr), but the determined Cr contents in plant crops in the Thiva basin are higher than normal or sufficient values. Although minimal uptake for growth and production for Cr, Ni, Zn and Cu is still lacking, furthermore research is required in order to restrict heavy metal accumulation and ensure sustainability.
On the speciation and the sources of chromium in groundwater in eastern Sterea Hellas, Greece: Natural versus anthropogenic origin.
MEGREMI. I., VASILATOS CH., ECONOMOU-ELIOPOULOS M. & MITSIS I.(2012). Accepted for presentation at the PRE.ORG, Protection and Restoration of the Environment XI, 2012-07-03, Thessaloniki.
Investigation of the water composition in Eastern Sterea Hellas, central Greece, has revealed high concentrations of... more Investigation of the water composition in Eastern Sterea Hellas, central Greece, has revealed high concentrations of Cr(total) in groundwater systems exceeding, sometimes, the Greek and the EU drinking water maximum acceptable level. Chemical analyses of the water samples were performed by using the GFAAS and ICP-MS for total chromium, diphenylcarbazide-Cr(VI) complex colorimetric method for hexavalent chromium, and flame-AAS and ICP-MS for other elements. The concentrations of Cr(VI) detected in several groundwater samples, range from < 1 (below detection limit) to 360g.L-1 in central Euboea and from < 1 to 153g.L-1 in Thiva–Tanagra–Malakasa basin, Eastern Sterea Hellas, Greece. The excellent correlation between Cr(VI) and Cr(total), indicates that hexavalent chromium is the predominant form of dissolved chromium in groundwater, with a pH near to neutral, regardless of its natural or industrial origin. Water samples from the Thiva–Tanagra–Malakasa basin are characterized by lower Fe and Mg contents compared to those from central Euboea. Based on Na, Fe, Ca, Mg, Si and Cr(VI) content of the water samples, several discrimination diagrams, have been proposed for the identification of their origin. According to their Na, Ca, Mg, Si and Cr contents, the water samples from central Euboea can be distinguished to a) those influenced by the sea water, having high Na very low Cr(total), b) those from the inner part of the island with lower Na and an average of 19g.L-1 Cr(total) and c) those with very high Cr(total) values, up to 390 g.L-1. The hydrochemical differences of the water samples from Euboea, suggest that in a) and b) cases, the ultramafic rocks of the area may be the source of the chromium, whilst in case c) the chromium content of the samples is probably associated with human activities, In Thiva–Tanagra–Malakasa basin the hexavalent chromium content of the water is associated with anthropogenic activities as well (industrial wastes).
Boron content of Lake Ulubat sediment: A key to interpret the morphological history of NW Anatolia, Turkey
Journal Article (2006). N. Kazanci, Ö. Toprak, S. A. G. Leroy, S. Öncel, Ö. Ileri, Ö. Emre, P. Costa, K. Erturaç and... more Journal Article (2006). N. Kazanci, Ö. Toprak, S. A. G. Leroy, S. Öncel, Ö. Ileri, Ö. Emre, P. Costa, K. Erturaç and E. McGee, Boron content of Lake Ulubat sediment: A key to interpret the morphological history of NW Anatolia, Turkey. Applied Geochemistry. 21. (134-151).
Arsenic Contamination of Groundwater in Dadu District, Sindh Province, Southern Pakistan
by Wajid Ali
Published in Journal of Science and Technology (2010)
In this study Arsenic concentration of groundwater samples collected from Dadu District, Sindh Province, Southern... more In this study Arsenic concentration of groundwater samples collected from Dadu District, Sindh Province, Southern Pakistan presented. About 30 water samples were collected for analysis of As Fe and other physico chemical parameters. Arsenic in the study area varies form 0-500 µg/l (mean 114 µg/l) while Fe ranges from 1.2 to 22 µg/l (mean 10.6 µg/l), TDS in 50 % of the samples are higher than the permissible limits set forth by World Health Organisation for drinking water. While As in 23 out of 30 samples shows concentration above the 10 µg/l limit, set forth internationally for drinking water. Groundwater in the study area is characterized as slightly alkaline, slightly-moderately saline and anoxic. Such chemical properties in addition to higher concentration of Fe in the groundwater of the study area may be responsible for the higher concentration of As in groundwater. All these conditions favor higher mobility and solubility of As in groundwater.
Assessment of NO 3− Contamination In a Karstic Aquifer, With the Use of Geochemical Data and Spatial Analysis
Kopaida plain is a cultivated region of Eastern Greece, with specific characteristic related with the paleogeographic... more Kopaida plain is a cultivated region of Eastern Greece, with specific characteristic related with the paleogeographic evolution and the changes in land use. The present article examines the contamination that derives from nitrates, in terms of contaminant levels, definition of sources and spatial distribution of contaminant plume. For this purpose, 50 water samples were collected from the karstic aquifer and analyzed for 15 parameters including major ions, trace elements, physicochemical parameters, and stable isotopes. The assessment of the above parameter values along with the notes derived by the statistical process revealed the existence of nitrate contamination which has been spatial defined with the aid of spatial interpolation techniques. The correlation of NO3 − concentrations with the stable isotope values, defined the infiltration conditions and showed contaminant transport. Nitrate values revealed the potential environmental threat for local people, as 10% of the samples exceeded the parametric value of 50 ppm and 54% of them are above 25 ppm, indicating no optimal quality conditions. The origin of nitrate contamination seems to derive exclusively from the application of N-fertilizers, since the rest of potential sources were not verified by analytical data and field works.
The Geochemistry of Boron-Rich Groundwater of the Karlovassi Basin, Samos Island, Greece
The upper Miocene of Karlovassi Basin, Samos Island, Greece, contain continental evaporites such as colemanite,... more The upper Miocene of Karlovassi Basin, Samos Island, Greece, contain continental evaporites such as colemanite, ulexite, celestite, gypsum and thenardite. These evaporites are related with volcanic tuffs, diagenetically altered in a saline-alkaline lake environment. The aim of the present paper is to: a) define the impact of the already known and possible buried borates and other evaporites to the geochemistry of the hydrogeological system of Karlovassi Basin, and; b) to assess the correlation between surface and underground evaporite deposits considering the spatial changes in the concentrations of the examined physicochemical parameters. Fieldwork, laboratory measurements and literature data revealed elevated boron values (2136-33012 μg/L) in the central part of Karlovassi Basin. In the same area, high amounts of strontium, sodium, lithium and sulfates also occur. It is proposed that these ions originate from the leaching of evaporites and authigenic minerals such as the Sr-rich clinoptilolite and the boron-bearing potassium feldspar. Boron values are abnormally high for freshwater aquifers, and are indicative of the presence of buried evaporites in the basin with unknown significance.
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Groundwater and Soil Geochemistry of the Eastern Kopaida Region (Beotia, Central Greece)
The upper Miocene of Karlovassi Basin, Samos Island, Greece, contain continental evaporites such as colemanite,... more The upper Miocene of Karlovassi Basin, Samos Island, Greece, contain continental evaporites such as colemanite, ulexite, celestite, gypsum and thenardite. These evaporites are related with volcanic tuffs, diagenetically altered in a saline-alkaline lake environment. The aim of the present paper is to: a) define the impact of the already known and possible buried borates and other evaporites to the geochemistry of the hydrogeological system of Karlovassi Basin, and; b) to assess the correlation between surface and underground evaporite deposits considering the spatial changes in the concentrations of the examined physicochemical parameters. Fieldwork, laboratory measurements and literature data revealed elevated boron values (2136-33012 μg/L) in the central part of Karlovassi Basin. In the same area, high amounts of strontium, sodium, lithium and sulfates also occur. It is proposed that these ions originate from the leaching of evaporites and authigenic minerals such as the Sr-rich clinoptilolite and the boron-bearing potassium feldspar. Boron values are abnormally high for freshwater aquifers, and are indicative of the presence of buried evaporites in the basin with unknown significance.
Pb, Cr, Ni and Cd contamination in Hand pump and Tap water of Mardan District
by Wajid Ali
principal author, published in The Environ Monitor, 2009 vol. IX (11-12)
This study was conducted in order to ascertain the present status of heavy metals in Hand pumps and tap water of
Mardan District. A total of eight heavy metals (Fe, Zn, Cu, Mn, Pb, Cr, Cd, and Ni) were investigated in hand pump
and tap water samples collected in the study area. Atomic Absorption Spectrometry was used to determine the heavy
metals. Fe, Zn and Cu levels were within the permissible limits, while Pb, Cr, Cd and Ni levels in the study area
exceeded the WHO permissible limits. The high concentration of heavy metals in the drinking water can be
attributed to the corrosiveness and aggressiveness of the water in the study area.Keywords: Mardan City, Drinking Water, Contamination, Stability Index, Plumbosolvency.