Heavy metal contamination in surface sediments of Gökçekaya Dam Lake,Eskişehir,Turkey

The present study to find seasonal (September 2010–June 2011) heavy metal (Cd, Pb, Cr, Co, Ni, Zn, Cu, Fe, As) contamination and the origins thereof in surface sediments of Gökçekaya Dam Lake, as constructed on Sakarya River, the third-longest river in Turkey and the largest river of the Northwestern Anatolia. Upon analyses for the purpose thereof, heavy metal contamination in annual average concentrations in the lake sediment varied, respectively, as Fe > Zn > Cr > Ni > Cu > Pb > Co > As > Cd. Statistical assessments performed in order to see whether the average values of the heavy metal contamination as measured at stations placed in the lake changed by seasonal periods. There found statistically significant differences especially in Cd, Zn, and Pb between seasonal periods. In accordance with the Sediment Quality Index, Gökçekaya Dam Lake sediment was classified as “highly polluted” in terms of the amount of anthropogenic contaminants of As, Cr, Cu, Ni, Pb, and Zn. Enrichment factor and geoaccumulation index values (I _geo) were calculated in order to geochemically interpret the source of contamination due to heavy metal concentration in the lake sediment and the level of pollution. The As, Co, Cr, Cu, Ni Pb, and Zn values demonstrated that the sediment was rich for anthropogenic contaminants. The lake was found especially rich for arsenic (14.97–34.70 mg/kg) and lead (68.75–98.65 mg/kg) in accordance with annual average values. In general the lake was geochemically characterized as “moderately contaminated” in terms of As, Co, Cr, Cu, Ni, Pb, and Zn content.     

Nitrate contamination in groundwater in the Sidi Aïch–Gafsa oases region, Southern Tunisia

Groundwater pumped from the semi-confined Complex Terminal (CT) aquifer is an important production factor in irrigated oases agriculture in southern Tunisia. A rise in the groundwater salinity has been observed as a consequence of increasing abstraction from the aquifer during the last few decades. All sources of contamination were investigated using hydrochemical data available from the 1990s. Water samples were taken from wells tapping both the CT and the shallow aquifers and analyzed with regard to chemistry tracers. Hydrochemical and water quality data obtained through a sampling period (December 2010) and analysis program indicate that nitrate pollution can be a serious problem affecting groundwater due to the use of nitrogen (N) fertilizers–pesticides in agriculture. The concentration of nitrate in an groundwater-irrigated area in Gafsa oases basin was studied, where abstraction from an unconfined CT aquifer has increased threefold over 25 years to 34 million m³/year; groundwater levels are falling at up to 0.7 m/year; and groundwater is increasingly mineralised (TDS increase from 500 to 4,000 mg/L), with nitrate concentrations ranging from 16 to 320 mg/L.     

Biostratigraphic Study of the Paleocene–Eocene Boundary in Northern Tunisia, North Africa

A new section at Jebel Gorraa,in northern Tunisia,contains the Paleocene-Eocene transition interval.Sample analysis of the section delivers abundant and diverse microfauna of planktonic and benthic foraminifera.Biostratigraphically,the Acarinina sibaiyaensis index-species is identified for the first time in this region,which allows us to specify the location of the Paleocene-Eocene boundary as well as the first E1 biozone of the lower Eocene.Samples from this biozone contain calcitic tests poorly preserved with an enrichment of iron oxide signifying a period of upheaval in local marine environments linked to the global warming of the Paleocene-Eocene Thermal Maximum （PETM）,the marker for the P/E boundary.     

Assessment of cadmium contamination in the sediments of Changjiang （Yangtze） River by reflectance spectroscopy

The Takab area in NW of Iran is an important gold mineralized region with a long history of gold mining. In this study ASTER data is used to evaluate environmental effects of gold mining. The results show that mining activities have resulted in release of potentially toxic metals （PTMs） in the area. Principal component analysis （PCA） of ASTER data is used to map sources of PTMs and their secondary hosts （iron oxides） through alteration mapping. The results show that selective PCA is a robust yet time consuming technique for alteration mapping. A color composite is created for finding common hydrothermally altered rocks. The created color composite successfully mapped the known deposits and anomalous areas identified by geological survey of Iran. Because of the low spatial resolution of ASTER sensor, the iron oxide mapping is restricted to the wider portions of the streams. Spectral analyses confirm the presence of hematite and goethite in stream sediments. This is in accordance with measured pH values.     

Analysis of the degree of contamination and evolution in the last 100 years of the composition of the bed sediments of the Anllóns Basin

In this study, five cores of the Anllóns River bed sediments were analyzed in order to evaluate the downcore and downstream variations in their chemical composition. The first step was the evaluation of the metal distribution in the bulk (<2 mm) and fine fractions (<63 μm). The analysis revealed that most of the metals followed the same trend in both fractions, although the fine fraction presented usually higher concentrations. However, the concentration of both fractions tended to equalize with increasing contamination. No general increase was observed in the metal concentrations toward the surface which could be attributed to recent anthropogenic contributions. Instead, the distributions were homogeneous or peaked at various depths downcore. The most important historical feature was observed at the mouth of the river, at 96-cm depth, corresponding to the end of the eighteenth century. Upcore increased metal concentrations in parallel with increased fine fraction occurred from this depth, which were attributed to a bridge construction and consequent changes in sediment dynamics. As the metal concentrations can be influenced by variations in texture or other sediment characteristics, the second step was to evaluate the efficiency of several normalized indexes in the assessment of the degree of contamination, by calculating the enrichment factor (EF), the geoaccumulation index (I _GEO) and the pollution load index (PLI). The EFs obtained were <10, thus revealing little anthropogenic inputs to the basin. The I _GEO produced higher values when compared with the EFs. Instead of absolute EF or I _GEO absolute values, the use of cumulative probability plots allowed identifying more accurately potential outliers indicating contamination. Only one population was identified for Zn and Pb, with a reduced number of outliers at the highest concentrations for Pb. As shown, a more complex plot with the outliers identified at C4 and C5. Finally, the PLI allowed determining the absence of a significant contamination in the bed sediments. The bioavailable and non-geogenic fractions contribute up to a 90% of the total concentrations in the case of As and Cu, and showed similar (dissimilar) profiles in comparison with total metals. Also, the quality guidelines were surpassed, so the high solubility of As, Zn, Pb and Ni in the sediments revealed the need to monitor the bed sediment quality of the Anllóns River.     

Sedimentary dynamics and ecological state of Nakta tidal flat (littoral), South of Sfax, Gulf of Gabès, Tunisia

The tidal flat of Nakta is located in the northern part of the gulf of Gabes and in the southern coast of Sfax. It corresponds to a flat reef protected from less topography, with a slope ranging between 2° and 4°, which borders the Gargour Wadi. The study sector is renowned to have moderate hydrodynamics which lasts almost for two millenary (14C isotopic dating). The sedimentological study of the Nakta tidal flat revealed different facies: fine-grained sand in the intertidal zone and carbonated muddy sand in the infratidal zone. Equilibrium state of the Nakta ecosystem depends entirely on tide currents, which mainly inhibit drift currents. The Nakta tidal flat is characterized by a variety of faunal species (Cerastoderma glaucum, Arca noe, Cardita antiquatus, Chlamys varied, Ruditapes deccussatus, Tapes rhomboids, Pinctada radiate, etc.) and floristic diversities (Halocnemum strobilacum, Halimione portulacoides, Enteromorpha linza, Ulva rigida, Cymodocea nodosa, Posidonia oceanica). The species are abundant in the infratidal zone, while in its intertidal zone, faunal species remain little diversified and are dominated by limivorous diggering. The paleogeographic study of the Nakta tidal flat showed the alternation of regression and transgression periods.     

Spatial and temporal variation of heavy metal contamination in sediments of Dexing region, Jiangxi Province, China

Mining is one of the most important contamination sources of heavy metals in sediments. Mining and mineral processing in the Dexing region of China have been carried out for over forty years. The aim of this study was to assess the spatial and temporal va…     

Influence of the halokinesis on the clay mineral repartition of upper Maastrichtian–Ypresian in the Meknassy-Mezzouna basin,centerwestern Tunisia

The Meknassy-Mezzouna basin is affected by a fault system, assembling two main directions, northsouth and eastwest. The Triassic outcrops are widely noticeable at Jebel Jebbes El Meheri and the Mezzouna link. During the late Maastrichtian–Ypresian, the sedimentation in the basin is influenced by halokinetic events, which are clearly manifested either by the thickness of El Haria formation along the Triassic outcrops (rim syncline) or by an alteration surface at the top of the Abiod formation. Such events also confirm the emersion of the basin from the late Maastrichtian to the early Lutetian. However, the present work tries to highlight the effects of halokinetic uplift on the clay mineralogical variations at that area. In harmony with this halokinetic activity, the clay minerals of this time interval (during the late Maastrichtian–Ypresian) show a trend of variation which corresponds to the evolution from illite and kaolinite, indicating a strongly hydrolytic marine environment, to smectite, sepiolite, and palygorskite, reflecting a very rapid evolution from this marine environment to a lagoon environment, then to a more confined continental environment. In fact, the appearance of sepiolite and palygorskite on the top of El Haria formation and the Paleocene–Eocene transition can be explained by a transformation or neoformation mechanism in an alkaline environment, rich in silica and magnesium, under arid to semi-arid climatic conditions. Moreover, the palygorskite can be formed in continental deposits as well as in close marine environment, which displays a limited communication with the open sea. Under these conditions, the evaporation leads to high ionic concentration of alkaline pH, which is favorable to the formation and stability of this mineral.     

Climatic control on the composition of Carboniferous–Permian Gondwana sediments,Khalaspir basin,Bangladesh

Late Paleozoic or Permo-Carboniferous Gondwana successions world-wide are marked by widespread and lengthy glaciation (~ 67 Ma), and multiple transitions from Icehouse to Greenhouse state. Mineralogical and compositional changes in sandstones and mudstones of the Gondwana succession in drill hole GDH-45 from the Khalaspir basin of Bangladesh are interpreted in a climatic framework, using the proxies of the Mineralogical Index of Alteration (MIA) and the Chemical Index of Alteration (CIA). Low MIA (< 75) and CIA (< 70) values in the lowermost unit (Unit 1) of the Khalaspir Gondwana sequence indicates minimal chemical weathering of the source and imply cold and dry glacial climatic conditions. Values increase progressively in the overlying Unit 2, suggesting warming and deglaciation. Very high MIA (80–100) and CIA (90–100) values in Unit 3 indicate intense chemical weathering associated with warm and humid climatic conditions in a post-glacial setting. These changes are recorded in both sandstones and mudstones, illustrating the value of acquiring data for a variety of size grades. The stratigraphic changes are also well recorded by progressively decreasing K₂O/Al₂O₃ and increasing Ga/Rb ratios, the combination of which may comprise a new geochemical proxy of climate and weathering. Upward increase in the modal Q / (F + L) and Qp / (F + L) ratios are also consistent with change from cool to warm and humid climate in the source region. The change in climatic conditions within the Khalaspir sequence is also well correlated with the Gondwana successions of other continental blocks, and records the climatic fluctuations and extent of climatic impact in Gondwanaland during the Permo-Carboniferous.     

Sedimentary dynamics and ecological state of Nakta tidal flat （littoral）, South of Sfax, Gulf of Gabès, Tunisia）

The tidal flat of Nakta is located in the northern part of the gulf of Gabes and in the southern coast of Sfax. It corresponds to a flat reef protected from less topography, with a slope ranging between 2° and 4°, which borders the Gargour Wadi. The study sector is renowned to have moderate hydrodynamics which lasts almost for two millenary （14C isotopic dating）. The sedimentological study of the Nakta tidal flat revealed different facies： fine-grained sand in the intertidal zone and carbonated muddy sand in the infratidal zone. Equilibrium state of the Nakta ecosystem depends entirely on tide currents, which mainly inhibit drift currents. The Nakta tidal flat is characterized by a variety of faunal species （Cerastoderma glaucum, Arca hoe, Cardita antiquatus, Chlamys varied, Ruditapes deccussatus, Tapes rhomboids, Pinctada radiate, etc.） and floristic diversities （Halocnemum strobilacum, Halimione portulacoides, Enteromorpha linza, Ulva rigida, Cymodocea nodosa, Posidonia oceanica）. The species are abundant in the infratidal zone, while in its intertidal zone, faunal species remain little diversified and are dominated by limivorous diggering. The paleogeographic study of the Nakta tidal flat showed the alternation of regression and transgression periods.     

Heavy metal concentrations in water and surface sediments of Maharlou Lake, SE of Shiraz, Iran

The main objective of this study is to evaluate trace metal distribution and identify their sources in the Maharlou Lake. Trace metals （Cr, Co, Ni, Cu, Zn, Cd, Pb） and major elements （A1, Ca, Fe, K, Mg, Mn, Na, P） were investigated in water and surface sediments. There was a negative relationship between the depth of water and heavy metal concentration. Metal concentrations in water and sediment samples show a high variability and decrease in this order： Al〉Fe〉Ni〉Co〉Pb〉Zn〉Cu〉Mn〉Cd. In the northern parts of the lake, especially at the inflow of drains and the Khoshk River of Shiraz City, metal concentrations are higher in both water and sediment samples. In order to assess the heavy metal enrichment in sediment samples, trace metal concentrations were normalized for Al. Except for Mn, all metals are enriched relative to average crust and average sedimentary rocks. Also, the results showed that stations located at the northern coast of the lake, have higher enrichment factors （EF） than the other stations. The results of this study showed that the Khoshk River and other drains are the main pollutant sources of the Maharluo Lake.     

Mineralogy of Precious Metals in Ores of the Biksizak Base–Metal Deposit,South Urals,Russia

Geology of Ore Deposits - Gold and silver mineralogy is studied in ores of the Biksizak base-metal deposit (South Urals, Russia). This is a skarn-related carbonate replacement mineralization...     

Elemental and organic geochemistry of Gondwana sediments from the Krishna–Godavari Basin,India

Elemental and organic geochemical studies have been carried out on the Gondwana sediments, collected from the outcrops of Permian and Jurassic–Cretaceous rocks in the Krishna–Godavari basin on the eastern coast of India, to understand their paleo and depositional environment and its implications for hydrocarbon generation in the basin. Amongst the studied formations, the Raghavapuram, Gollapalli and Tirupati form a dominant Cretaceous Petroleum System in the west of the basin. Raghavapuram shales and its stratigraphic equivalents are the source rock and Gollapalli and Tirupati sandstones form the reservoirs, along with basaltic Razole formation as the caprock. Major element systematics and X-ray diffraction study of the sandstones indicate them to be variably enriched with SiO₂ relative to Al₂O₃ and CaO, which is associated, inherently with the deposition and diagenesis of the Gondwana sediments. Post-Archean Average Shale normalized rare earth elements in shales show enrichment in most of the samples due to the increasing clay mineral and organic matter assemblage. A negative europium and cerium anomaly is exhibited by the REE's in majority of rocks. Composed primarily of quartz grains and silica cement, the Gollapalli and Tirupati sandstones have characteristics of high quality reservoirs. The shales show a significant increase in the concentration of redox sensitive trace elements, Ni, V, Cr, Ba and Zn. The total organic carbon content of the shales ranges between 0.1 and 0.5 wt%. Programmed pyrolysis of selected samples show the Tmax values to range between 352–497 °C and that of hydrogen index to be between 57–460 mgHC/gTOC. The organic matter is characterized by, mainly, gas prone Type III kerogen. The n-alkane composition is dominated by n-C₁₁–C₁₈ and acyclic isoprenoid, phytane. The aromatic fraction shows the presence of naphthalene, anthracene, phenanthrene, chrysene and their derivatives, resulting largely from the diagenetic alteration of precursor terpenoids. The organic geochemical proxies indicate the input of organic matter from near-shore terrestrial sources and its deposition in strongly reducing, low oxygen conditions. The organic matter richness and maturity derived from a favorable depositional setting has its bearing upon the Gondwana sediments globally, and also provides promising exploration opportunities, particularly in the Raghavapuram sequence of the KG basin.     

High-resolution aquifer analog of fluvial–aeolian sediments of the Guarani aquifer system

The Guarani aquifer system (GAS) represents one of the biggest aquifers in the world and is the most relevant groundwater resource in South America. For the first time, by combining field and laboratory measurements, a high-resolution aquifer analog model of fluvial–aeolian sediments of the GAS in São Paulo State (Brazil) is constructed. Three parallel sections of frontal outcrops, 28 m × 5.8 m, and two parallel sections of lateral outcrops, 7 m × 5.8 m, are recorded during open-pit mining of sandy sediments and describe in detail the three-dimensional distribution of the local lithofacies and hydrofacies. Variations of hydraulic conductivity, K, and porosity, n, are resolved on the centimeter scale, and the most permeable units of the fluvial–aeolian facies association are identified. The constructed aquifer analog model shows moderate hydraulic heterogeneity and a mean K value of 1.36 × 10^?4 m/s, which is greater than the reported range of K values for the entire GAS in São Paulo State. The results suggest that the examined sedimentary unit constitutes a relevant portion of the GAS in São Paulo State in the context of groundwater extraction and pollution. Moreover, the constructed aquifer analog is considered an ideal basis for future numerical model experiments, aiming at in-depth understanding of the groundwater flow and contaminant transport patterns at this GAS portion or at comparable fluvial–aeolian facies associations.     

Upper Miocene–Eopleistocene terrestrial sediments of the northwestern Ciscaucasia region

On the basis of their stratigraphic, lithological, and genetic features, the Upper Miocene–Eopleistocene terrestrial sediments of the northwestern Ciscaucasia region are subdivided into the following local stratigraphic units (formations): Azov–Kuban, Srednyaya Kuban, Novoaleksandrovsk, Temizhbekskaya. The paleontological and paleomagnetic data are used for determining or specifying their age and correlating the formations between each other and with the regional stratigraphic scale. The obtained data make it possible to improve the Upper Miocene–Eopleistocene stratigraphic scale of the northwestern Ciscaucasia region.     

Metal and metalloid leaching from tailings into streamwater and sediments in the old Ag–Pb–Zn Terramonte mine,northern Portugal

Tailings deposited over the Castanheira, a stream which flows through the old Ag–Pb–Zn Terramonte mine area, showed a great potential environmental risk due to sulphide weathering, facilitated by the tailings–water interaction. The high concentrations of Al, Fe, Pb and Zn in the tailings are associated with the exchangeable, reducible and sulphide fractions and suggest sphalerite and pyrite occurrences. Oxidation of pyrite is responsible for the low pH values (3.38–4.89) of the tailings. The water from the Castanheira stream is not suitable for human consumption due to high concentrations of SO₄ ^2?, Mn, Al, Cd, Ni, and Pb. The lowest concentrations of metals and metalloids were detected in downstream stretches of the Castanheira. However, As, Fe and Zn in deeper sediments tend to increase downstream. Significant concentrations of trivalent forms of arsenic were detected in water samples. In downstream stretches of the Castanheira, some free ions (Fe²⁺, Mn²⁺ and Zn²⁺) also predominate and the water is saturated with ferrihydrite, goethite, hematite, lepidocrosite and magnetite.     

Genesis,Features of Mineral Composition,and Problems of the Development of Rare Metal–Titanium Placers in the West Siberian Megaprovince

Lithology and Mineral Resources - The coastal-marine rare metal–titanium placers of the West Siberian megaprovince were formed in a relatively short Eocene–Late Oligocene interval. A...     

Environmental assessment of heavy metal contamination in bottom sediments of Al-Kharrar lagoon,Rabigh, Red Sea,Saudi Arabia

In order to assess the pollution levels of selected heavy metals, 45 bottom sediment samples were collected from Al-Kharrar lagoon in central western Saudi Arabia. The concentrations of the heavy metals were recorded using inductively coupled plasma-mass spectrometer (ICP-MS). The results showed that the concentrations of Pb and Cd exceeded the environmental background values. However, the heavy metal contents were less than the threshold effect level (TEL) limit. The concentrations of heavy metals in lagoon bottom sediments varied spatially, but their variations showed similar trends. Elevated levels of metals were observed in the northern and southern parts of the lagoon. Evaluation of contamination levels by the sediment quality guidelines (SQG) of the US-EPA revealed that sediments were non-polluted-moderately to heavily polluted with Pb; non-polluted to moderately polluted with Cu; and non-polluted with Mn, Zn, Cd, and Cr. The geoaccumulation index showed that lagoon sediments were unpolluted with Cd, Mn, Fe, Hg, Mo, and Se; unpolluted to moderately polluted with Zn and Co; and moderately polluted with Pb, Cr, Cu, and As. The high enrichment factor values for Pb, As, Cu, Cr, Co, and Zn (>2) indicate their anthropogenic sources, whereas the remaining elements were of natural origins consistent with their low enrichment levels. The values of CF indicate that the bottom sediments of Al-Kharrar lagoon are moderately contaminated with Mn and Pb.     

Zinc contamination in river water and sediments at Taisyu Zn–Pb mine area,Tsushima Island,Japan

Tsushima Island is one of the oldest zinc-lead mining areas in Japan. River water and sediment samples were collected mainly from Taishu area to determine the contamination level of Zn and to clarify its behaviour in the natural system. Among the water samples analysed, 64% exceeded the standard environmental limit of 0.03 µg ml^− 1 for Zn. In most cases, Zn concentration in sediment samples also exceeded the standard value, and the concentration varied from 86.75–7490.07 µg g^− 1. The mineralogical constituents in sediments were almost similar and quartz had the strongest peak, but the interior part of the ores had many minerals, with galena having the highest proportion. Considering the enrichment factor values (EFc), 12 samples have values of more than 50, indicating a high pollution load for Zn. This study revealed that the sulphide ores, and contaminated sediments, are the possible contamination sources of Shiine River, and Zn dissolution occurred by reactions, such as desorption and ion exchange.