Trace metal deposition and mobility in the sediments of two lakes near Sudbury,Ontario

The accumulation and mobility of Fe, Mn, Al, Cu, Ni and Pb in the sediments of two lakes (Clearwater, pH 4.5; and McFarlane, pH 7.5) near Sudbury, Ontario have been investigated. The Al, Cu and Ni concentrations are expectedly relatively high in the overlying waters of Clearwater Lake and much lower for Al and Cu in McFarlane Lake. The low trace metal concentrations found in the anoxic porewaters of Clearwater Lake could be explained by a sharp increase in porewater pH concomitant with SO₄² reduction and H₂S production within the first 1–2 cm of the sediments, which has conceivably led to the precipitation of mineral phases such as AL(OH)₃, NiS, and CuS. In both lakes, Fe concentrations in anoxic porewaters appear to be controlled by FeS and/or FeCO₃ formation. Solubility calculations also indicate MnCO₃ precipitation in McFarlane Lake. In Clearwater Lake, however, both porewater and total Mn were relatively low, a possible result of the continuous loss of Mn(II) through the acidic interface. It is suggested that upwardly decreasing total Mn profiles resulting from the removal of Mn from the top sediment layers under acidic conditions may constitute a reliable symptom of recent lake acidification.The downward diffusion of AI, Cu and Ni from the overlying water to the sediments has been estimated from their concentration gradients at the interface and compared to their total accumulation rates in the sediments. In both lakes the diffusion of Al is negligible compared to its accumulation rate. However, diffusion accounts for 24–52% of the accumulation of Cu in the sediments of Clearwater Lake, but appears negligible in McFarlane Lake. The downward diffusive flux of Ni is important and may explain 76–161% of the estimated Ni accumulation rate in Clearwater Lake, and 59% in McFarlane Lake. The porewater Cu and Ni profiles suggest that the subsurface sedimentary trace metal peaks observed in Clearwater Lake (as in other acid lakes) may not be caused by sediment leaching or by a recent reduction in sedimentation but may have a diagenetic origin instead. Diffusion to the sediments thus appears to be an important and previously overlooked trace metal deposition mechanism, particularly in acid lakes.     

Geochemical characteristics of water and sediment from the Dal Lake, Kashmir Himalaya: constraints on weathering and anthropogenic activity

Two hundred and forty water samples (in four seasons) and seventeen sediment samples have been analyzed to monitor the natural and anthropogenic influences on the water and sediment chemistry of the Dal Lake, Kashmir Himalaya. The scatter diagrams [(Ca+Mg)/total cations (TZ⁺), (Ca+Mg)/HCO₃, (Ca+Mg)/(HCO₃₊SO₄), (Na+K)/TZ⁺; (Ca+Mg)/(Na+K)] and the geological map of the study area suggest predominance of carbonate and silicate weathering. Lower pH and high total dissolved solids, electrical conductivity and values in the Gagribal basin and in some patches of other basins reflect anthropogenic inputs in the form of sewage from surrounding population, houseboats, hotels, etc. The Dal Lake is characterized by high chemical index of alteration (CIA: 87–95), reflecting extreme weathering of the catchment area. Relative to the average carbonates, the lakebed sediments are enriched in Al, Ti, Zn, Cu and Co and depleted in Ni and Mn. Compared to the post-Archean Shale the sediments have higher Al, Zn and Cu contents and lower Ni and Co. There are distinct positive anomalies of Al, Mn, Zn and Cu and negative anomalies of Ni and Pb with respect to the upper continental crust. Geoaccumulation index (I _geo) and the US Environmental Protection Agency sediment quality standards indicate that the Gagribal basin and some patches of the Nagin basin are polluted with respect to Zn, Cu and Pb. These data suggest that the Dal Lake is characterized by differential natural and anthropogenic influences.     

近50年来抚仙湖重金属污染的沉积记录*

文章以抚仙湖污染严重的北部和基本未受人类活动影响的中部为研究对象,分别采集了沉积岩芯FB和FZ,通过对岩芯的¹³⁷ Cs测年和重金属元素(Cu,Ni,Ti,Cr,V,Pb,Cd和Zn)的含量分析,研究了湖泊重金属来源和污染历史,并利用地质累积指数法评价了湖泊重金属污染程度。结果表明:抚仙湖北部的平均沉积速率约为2.0~2.8mm/a;20世纪80年代以前,湖泊北部和中部的重金属元素(Cu,Ni,Ti,V,Pb,Cd,Zn)以自然来源为主;80年代以后,抚仙湖受到人类活动的影响,但湖泊中部Cu,Ni,Ti,V,Pb,Zn以及湖泊北部Cu,Ni,Ti,V仍以自然来源为主;湖泊北部Pb和Zn地质累积指数值小于1,属无污染到中度污染;北部Cd地质累积指数为3~4,达强度污染;中部Cd地质累积指数为2~3,属中强度污染;且Pb,Zn和Cd污染程度有加速增大的趋势。     

Weathering and anthropogenic influences on the water and sediment chemistry of Wular Lake,Kashmir Himalaya

This paper presents a study on the Wular Lake which is the largest fresh water tectonic lake of Kashmir Valley, India. One hundred and ninety-six (196) water samples and hundred (100) sediment samples (n = 296) have been collected to assess the weathering and Anthropogenic impact on water and sediment chemistry of the lake. The results showed a significant seasonal variability in average concentration of major ions being highest in summer and spring and lower in winter and autumn seasons. The study revealed that lake water is alkaline in nature characterised by medium total dissolved solids and electrical conductivity. The concentration of the major ion towards the lake central showed a decreasing trend from the shore line. The order of major cations and anions was Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and HCO₃ ^? > SO₄ ^2? > Cl^?, respectively. The geochemical processes suggested that the chemical composition lake water is mostly influenced by the lithology of the basin (carbonates, silicates and sulphates) which had played a significant role in modifying the hydrogeochemical facies in the form of Ca–HCO₃, Mg–HCO₃ and hybrid type. Chemical index of alteration values of Wular Lake sediments reflect moderate weathering of the catchment area. Compared to upper continental crust and the post-Archean Shale, the sediments have higher Si, Ti, Mg and Ca contents and lower Al, Fe, Na, K, P, Zn, Pb, Ni, Cu content. Geoaccumulation index (Igeo) and US Environmental Protection Agency sediment quality standards indicated that there is no pollution effect of heavy metals (Zn, Mn, Pb, Ni and Co).The study also suggested that Wular Lake is characterised by both natural and anthropogenic influences.     

The variability of δ34S and sulfur speciation in sediments of the Sulejów dam reservoir (Central Poland)

The study was carried out on the Sulejów dam reservoir (Central Poland). Water and sediment samples were collected between February and October 2006. Sulfur compounds in the sediment were chemically extracted and subjected to isotopic analysis.Large variability of SO₄²⁻ concentration in the water column (from 10.3 to 36.2 mg/dm³) and the isotopic composition of sulfur (δ³⁴S from 2.1 to 5.4‰) was observed. The main identified sources of SO₄²⁻ were watercourses, surface runoff, and phosphorus fertilizers.Both oxidized sulfur species (SO₄²⁻) and its reduced forms were found in sediments. Particular sulfur forms were characterized by large variations in both, concentrations and the isotopic composition of sulfur. SO₄²⁻ in the sediment and in the water column had different genesis. Bacterial oxidation of organic sulfur and its binding in SO₄²⁻ were observed in the sediment. Under reducing conditions, oxidized and organic sulfur is converted to H₂S which reacted with Fe or other metallic ions leading to metal sulfide precipitation. Monosulfides were shown to have a very low concentration, ranging up to 0.07 mg/g of sediment. The transformation of elemental sulfur from sulfides through their chemical oxidation occurred in the sediment.     

Biogeochemistry of trace metals (Mn, Sr, Rb, Ba, Cu, Zn, Pb and Cd) in a river-wetland-lake system (Balaton Region, Hungary)

Mn, Sr, Ba, Rb, Cu, Zn, Pb and Cd concentrations have been measured seasonally in the water and deposited sediments of the system comprising: Zala river (main input) — Lakes Kis-Balaton 1 and 2 (small artificial lakes created in a former bay of Lake Balaton) — Keszthely bay (hypertrophic part of Lake Balaton). The concentrations of the trace elements together with pH, alkalinity, dissolved cations (Ca²⁺, Mg²⁺, Na⁺, and K⁺), dissolved inorganic ligands (Cl^–, SO₄ ^2–), particulate Al, Ca, inorganic and organic carbon are used to assess the contamination of the study area and biogeochemical processes controlling trace element concentrations. Thermodynamic speciation calculations have also been utilized to enhance our understanding of the system. In the sediments Rb, Ba, Cu and Zn concentrations were mainly controlled by the abundance of the aluminosilicate fraction. Strontium was mainly associated with the calcium carbonate fraction. The aluminosilicate fraction constitutes a major sink for Mn and Cd but the concentration of these elements are also strongly related to calcite precipitation. The main processes that control the dissolved distribution of trace elements in the Balaton system were: solid phase formation (carbonate) for Mn; coprecipitation with calcite for Sr, Ba, Rb and possibly Mn and Cd; adsorption/desorption processes (pH dependent) for Zn and Pb; solubilization of Mn and precipitation of Cd and Cu in reed covered wetland areas where anoxic conditions were probably existing during the warm season. A preliminary budget of atmospheric and river input to Lake Balaton has also been outlined. Although Lake Balaton, is subjected to anthropogenic inputs mainly from agricultural and domestic activities, their impact on trace element concentrations in the Balaton system is very limited due to the efficiency of removal processes (i.e. adsorption and co-precipitation) and to high sedimentation rates and strong sediment re-suspension. Anthropogenic inputs are only detected for Pb.     

Environmental pollution impact on water and sediments of Kumaun lakes, Lesser Himalaya, India: a comparative study

A study of the water and sediment chemistry of the Nainital, Bhimtal, Naukuchiyatal and Sattal Lakes of Kumaun, has shown that the water of these lakes are alkaline and that electrical conductivity, total dissolved solid and bicarbonate HCO ₃ ⁻ are much higher in Nainital than in the other three lakes. The weathering of limestone lithology and anthropogenic pollution, the latter due to the very high density of population in the Nainital valley, are the primary sources of enhanced parameters. The low pH of Nainital Lake water is due to low photosynthesis and enhanced respiration, increasing CO₂ in the water and the consequent enhancement of Ca²⁺ and HCO ₃ ⁻ . The dissolved oxygen in Nainital Lake is less compared to other lakes, indicating anoxic conditions developing at the mud–water interface at depth. The PO ₄ ³⁻ content in Nainital is higher (124 μg/l), showing an increasing trend over time leading to eutrophic conditions. The trace metals (Cu, Co, Zn, Ni, Mn, and Sr) are present in greater amounts in the water of Nainital Lake than in the other three lakes, though Fe and Cr are high in Bhimtal and Fe in Naukuchiyatal. The higher abundance is derived from the leaching of Fe–Mg from metavolcanic and metabasic rocks. Most of the heavy metals (Cr, Ni, Cu, Mn, Fe, Sr, and Zn) significantly enrich the suspended sediments of the lakes compared to the bed sediments which due to their adsorption on finer particles and owing to multiple hydroxide coating and organic content, except for Fe, which is enriched in the bed sediments. The high rate of sedimentation, 11.5 mm/year in Nainital, compared to Bhimtal with 4.70 mm/year, Naukuchiyatal with 3.72 mm/year, and Sattal with 2.99 mm/year, has resulted in shorter residence time, poor sorting of grains, and lesser adsorption of heavy metals, leading consequently, their depletion in the bed sediments of Nainital Lake.     

Mobility and impact of trace metals in Barapukuria coal mining area, Northwest Bangladesh

Trace metals were analyzed in water and sediment samples from Barapukuria coal mine area of Bangladesh in order to evaluate their mobility and possible environment consequences. Cadmium is the most mobile element with an average partition coefficient (log K _d ) of 2.95 L/kg, while V is the least mobile element with a mean log K _d of 5.50 L/kg, and their order of increasing mobility is: V < As < Pb < Fe < Cr < Se < Mn < Ni < Zn < Cu < Ba < Sr < Cd. Contents of organic carbon in sediment samples shows strong positive correlations with most trace metals as revealed by the multivariate geostatistical analysis. The overall variation in concentration is mainly attributed to the discharge of effluents originating from the coal mining activities around the study area. Compared to their background, Ni and Cu are the most enriched while significant enrichment of As, Mn, Ba, Sr, Cr, and Pb is also observed in the sediments. Geoaccumulation indices (I _geo ) suggest sediments are moderately to heavily polluted with respect to Ni and Cu. The metal pollution index (MPI) varied from 91.91 to 212.01 and the highest value is found at site CM03 that is close to discharge point. The sediment quality guideline index (SQG-I _Intervention ) values (0.56–1.52) suggest that the sediments at the study area have moderate to high ecotoxicological risk.     

Heavy metal history from cores in Wellington Harbour,New Zealand

Analysis of ten heavy metals (Ag, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Zn) in six sediment cores from Wellington Harbour show both anthropogenic enrichments and diagenetic modifications. Absolute concentrations determined by two methods, x-ray fluorescence and acid leaching for bioavailability, are not comparable. However, vertical trends in concentrations of the cored sediment are comparable. To assess levels of anthropogenic pollution, enrichment factors (enriched concentrations in upper core divided by background levels in lower core) are preferred over index of accumulation (I _geo) values because preindustrial or background levels of heavy metals are well constrained. The ten metals are placed into three groups: (1) Cu, Pb, and Zn, which show the most anthropogenic enrichment; (2) As, Cd, Cr, Ni, and Sb, which are often associated with anthropogenic pollution but show only minor enrichment; and (3) Fe and Mn, which are diagenetically enriched. Assuming harbor waters are well mixed, anthropogenic enrichments of Cu, Pb, and Zn, are time correlative, but the degree of enrichment depends on the method of analysis and core location. Levels of As, Cd, Pb, and Zn show small variations in preindustrial sediments that are not related to changes in grain size and probably result from changes in the oxidation-reduction potential of the sediments and salinity of the pore waters.     

Preparation and solubility of northupite from brine and its adsorption properties for Cu(II) and Cd(II) in seawater

The mineral northupite Na₃Mg(CO₃)₂Cl was synthesized from a solar Adriatic seawater brine pond to which Na₂CO₃ was added at 373°K. The precipitated northupite had a surface area (P) of 6.0 ± 0.4 m²g⁻¹, and the thermodynamic solubility product was estimated to be log K Na₃Mg(CO₃)₂Cl = −4.8 ± 0.3 at 25°C. This value was used to calculate the interfacial energy (σ = 50 erg cm⁻²) for the homogeneous nucleation of northupite. The solubility constant determined in this study has been used to examine the saturation state of Mahega Lake and Lake Katwe (Uganda). The waters from Lake Katwe were found to be supersaturated with respect to northupite.The adsorption of Cu and Cd onto northupite particles was studied in seawater. Both metals are strongly adsorbed. Adsorption constants and the specific area of northupite occupied by Cd and Cu using Langmuir adsorption isotherms and equilibrium constants for surface complex formation have been determined.     

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Metals in lacustrine sediment have both anthropogenic and natural sources. Because of intensified human activities, the anthropogenic input of metal elements has exceeded the natural variability. How to distinguish the anthropogenic sources in lake sediments is one of the tasks in environmental management. The authors present a case study, which combined the geochemical and statistical methods to distinguish the anthropogenic sources from the natural background. A 56 cm core (core DJ-5) was collected from Dongjiu Lake, Taihu Lake catchment, China. The concentration distributions of Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, Ti, V and Zn in core DJ-5 indicated that Dongjiu Lake had serious Cd pollution, and the concentrations of Cr, Cu, Pb, Mn and Zn had also exceeded the Chinese State Standards of Soil Environmental Quality in the upper layer of the core. Using Al as a reference element, the other metals were normalized and compared with their baselines to calculate the enrichment factors (EFs). The principal component analysis (PCA) of metal concentrations was performed using ViSta6.4. The results of EFs and PCA indicated that the concentration variations of Cd, Cu, Pb, Mn and Zn were mainly caused by the anthropogenic sources, and the concentration variations of Cr and Ni were influenced by both the anthropogenic and natural factors, while the other metals were mainly derived from the natural sources. Intensified human activities within the lake catchment area resulted in the increase of heavy metal inputs directly and the acceleration of erosion which caused other metal elements to deposit in the aquatic environment. The results of this work will be useful in probing changes forced by humans in the lake environment and in adjusting human activity in restoring the lake environment.

Geochemistry and anthropogenic inputs of metals in a tropical lake in Venezuela

Lake Valencia is a tropical lowland lake in north-central Venezuela. Lake bottom sediments were collected from 25 locations in April, 1988. At 2 locations water pH, conductivity, dissolved O₂ and temperature were measured at successive depths. After drying, 5 sediment samples were sieved into 5 mechanical fractions. Each was extracted with 1 M HNO₃ and analysed for AI, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn. The <63 μm fraction of all samples was similarly analysed. Water temperatures declined with depth (1°C/25 m) from approximately 26°C. Conductivity varied little with depth but dissolved O₂ contents indicated anoxic conditions < 25 m. Water pH (8.8–9.4) was consistent with high dissolved carbonates. There was little consistent relationship between grain size and sediment metal contents. Approximate baseline metal contents were calculated from 21 of 25 samples. The average composition of the sediments corresponded to an ideal mixture of shales/carbonate rocks as 0.5–0.7/0.5-0.3. Five samples from alluvial fans near the mouths of rivers traversing urban-industrial zones had compositions different from the other sediments. Generally, Ph, Zn, Ni, Cd and Cu were anthropogenically enriched by factors of 2–16. The major sources of pollutants were identified as domestic and industrial activities affecting the rivers that traverse the lakeside cities of Maracay and Valencia. Sodium, Mg, Ca, Mn and CO₃⁻ showed natural enrichment arising from carbonate precipitation following a physical mixing of 2 sedimentary components (biogenic carbonate and terrigenous material). Low geochemical mobility of metallic elements in neutral-basic and reducing waters, a processes of bury and mixture of sediments and precipitation of carbonate result in only 10% of the lake area being affected by contamination. Isoline plots of elements in the bottom sediments supported a hypothesis that material mixing, physical transport and carbonate precipitation are the main controls of spatial distribution patterns.     

Heavy metals pollution on the sediments in lakes Dianchi, Erhai and Poyanghu and historical records

In this paper²¹⁰ Pb and ¹³⁷Cs dating methods were used to determine sedimentation rates of lakes Dianchi, Erhai and Poyanghu, and to establish the time scale of the sediments. Also based on geochemical records in the sediment column, the historical variation in heavy metal content over the past one hundred years was determined. Some element concentration increased rapidly after the 1970s, such as Cu, Zn and Mn in the sediments of northern Lake Dianchi, Cd and Mn in southern Lake Erhai and in the west central parts of Lake Poyanghu, Our investigations indicate that the increase in element concentration is caused by human activities. In order to understand the extent of the effect caused by human activities, we have calculated the flux of Zn, Cd and Mn. Results show that the flux caused by human activities is seven times greater than the natural one and the ratio is about 2 times in Lake Erhai and Lake Poyanghu.     

Accumulation rates of Th-230, Pa-231, and some transition metals on the Bermuda Rise

Measurements of ²³⁸U, ²³⁴U, ²³⁰Th, ²³²Th, ²³¹Pa, Mn, Fe, Co, Ni, Cu, and Zn were made on 23 samples from core GPC-5, a 29-m giant piston core from a water depth of 4583 m on the northeastern Bermuda Rise (33°41.2′N, 57°36.9′W). This area is characterized by rapid deposition of sediment transported by abyssal currents. Unsupported ²³⁰Th and ²³¹Pa are present throughout the core but, because of large variations in the sedimentation rate, show marked departures from exponential decay with depth. The trend with depth of the ${}^{231}\text{Pa}{}_{\mathrm{ex}}{}^{230}\text{Th}{}_{\mathrm{ex}}$ ratio is consistent with the average accumulation rate of 36 cm/1000 y reported earlier on the basis of radiocarbon dating and CaCO₃ stratigraphy. When expressed on a carbonate-free basis, concentrations of Mn, Co, Ni, Cu, Zn, ²³⁰Th_ex, and ²³¹Pa_ex all show cyclic variations positively correlated with those of CaCO₃. The correlations can be explained by a model in which all of these constituents, including CaCO₃, are supplied to the sediments from the water column at a constant rate. Concentration variations are controlled mainly by varying inputs of terrigenous detritus, with low inputs occurring during interglacials and high inputs during glacials. Relationships between the metal and ²³⁰Th_ex concentrations permit estimates of the rates at which the metals are removed to the sediment by scavenging from the water column. The results, in μg/cm²-1000 y, are: 4300 ± 1100 for Mn, 46 ± 16 for Ni and 76 ± 26 for Cu. These rates are somewhat larger than ocean-wide averages estimated by other methods, and the absolute rate of ²³⁰Th accumulation in GPC-5 averages about nine times higher than production in the overlying water column. This part of the Bermuda Rise and similar bottom-current deposits may act as important accumulators of elements scavenged from seawater.     

Geochemical data as indicators of environmental change and human impact in sediments derived from downstream marshes of an ephemeral river,Northeast China

Recent sedimentary history of natural environmental change and anthropogenic influence in an ephemeral river catchment has been reconstructed using selected major and trace elements, element ratios, and their different geochemical phases (Tessier sequential extraction methods), pollen, and grain size combined with ²¹⁰Pb- and ¹³⁷Cs-dating method in marsh sedimentary cores. Attempts were made to use selected element ratios with different geochemical phases—residual phase of Ti, Al, V, Cr, Ni, Rb, K, Sr, and Ba; mobile Sr and Ba—combined with ²¹⁰Pb- and ¹³⁷Cs-chronology to interpret certain time information of environmental changes saved within the marsh sediments. Results indicate that there were two marked humid periods during 1850–1860 ad and 1890–1920 ad, and sand storm activities prevailed during 1920–1930 ad. After about 1900 ad, soil erosion has increased with the extensive agricultural activities in the Huolin River catchments, and further intensified after 1950s. After 1980, soil erosion has become even more intense, which is consistent with the reinforcement of human activities, the drastic loss of vegetation cover in the upstream lands, especially, the exploitation of the open cast coalmine in the upstream of Huolin River at that time. Influenced by the inundation of the Huolin River, the heavy metal pollution historical trends in Xianghai marsh wetland could be roughly divided into three periods by analysis of sediment enrichment factor (K_SEF) and the index of geoaccumulation (I _geo):1760–1880 ad, 1880–1980 ad, and 1980–now. Human activities accelerate the inputs of heavy metal, which leads to degradation of the marsh. This study also investigated on source of marsh sediments (by Ti/Al), redox condition [by V/Cr and V/(V + Ni)], and salinization indicators (by Sr/Ba and Rb/K). The results demonstrate that sources of sediments and redox conditions were partly similar for both riparian and depressional marshes. Besides, some differences in degree of salinization between two types of marsh were also identified, especially after 1880.     

Temporal and spatial distribution of trace metals in sediments from the northern Yellow Sea coast,China: implications for regional anthropogenic processes

Surface sediment samples from 17 sites in the Yantai coastal area, the northern Yellow Sea, China, combined with a sediment core were employed for geochemical and chronological analyses for the purpose of characterizing the temporal and spatial distribution of trace metals in sediments and their implications for anthropogenic processes. The results indicated that the spatial distribution of trace metals (Cr, Ni, Ti, Pb, As, Zn, Mn and Cu) in surface sediments was significantly contributed by the sewage discharges along the Yantai coast, and the coastal currents played a major role for transporting the pollutants to offshore. The temporal concentrations of trace metals in the sediment core based on the chronology determined by a combination of radionuclide ¹³⁷Cs and ²¹⁰Pb activity demonstrated that trace metal concentrations increased step-wisely over the last ca. 100 years, corresponding to the intensity of anthropogenic processes in the Yantai area. The high levels of Cu and As before the late 1970s indicated the agricultural emission from the application of pesticides. While, all the high-trace metal concentrations since the early 1980s could be seen as diagnostic indictors of increasing industrialization, urbanization and sewage discharge in the Yantai area. Although the potential ecological risk evaluation of trace metals in the coastal area suggests low-potential ecological risk at present, some trace metals, such as As and Pb need particular attention due to their slight contamination.     

Assessment of heavy metals in sediments near Hazira industrial zone at Tapti River estuary, Surat, India

Heavy metal accumulation due to industrial activities has become a very sensitive issue for the survival of the aquatic life. Therefore, distributions of several heavy metals have been studied in the surface sediments of Tapti–Hazira estuary, Surat, to assess the impact of anthropogenic and industrial activities near estuary. Totally 60 sediment samples were collected from four different sites at Tapti–Hazira estuary, Surat from January 2011 to May 2011 and examined for metal contents. The average heavy metal load in the study area are found to be 43.28–77.74 mg/kg for Pb, 48.26–72.40 mg/kg for Cr, 117.47–178.80 mg/kg for Zn, 71.13–107.82 mg/kg for Ni, 123.17–170.52 mg/kg for Cu, 0.74–1.25 mg/kg for Cd, 14.73–21.69 mg/kg for Co. Calculated enrichment factors (EF) reveal that enrichment of Pb and Cd is moderate at all sites, whereas other metals Cr, Ni, Zn, Co, and Cu show significant to very high enrichment. Geo-accumulation index (I _geo) results revealed that the study area is nil to moderately contaminated with respect to Cd, moderately to highly polluted with respect to Pb, Zn, and Cu and high to very highly polluted with respect to Co and Cr.     

Review of water and soil contamination in and around Salihli geothermal field (Manisa,Turkey)

The town of Salihli is situated in Gediz Graben in the western Anatolia. This region is important in terms of industry, mining, geothermal energy, water sources, and agricultural production. Geothermal flow and anthropogenic activities in Salihli threaten the surrounding environment due to the contamination of cold groundwater, surface water, and soil. The goal of the present study is to determine the environmental effects of the geothermal and anthropogenic activities in Salihli on soil, stream sediments, and water. Stream sediments and farm soil have been contaminated by substances derived from geothermal and industrial effluents. To this end, the quality review of the water was completed and the heavy metal levels in stream sediment samples were measured to determine the extent of contamination. The elements As, B, Br, Fe, and Ni are the major contaminants present in surface water and groundwater in the study area. The concentrations of these elements excess tolerance limits of international water standards. Gibbsite, K-mica, kaolinite, sepiolite, halite, sulfur, willemite, and Pb(OH)₂ might be precipitated as scales at low temperatures on the soil; this could be interpreted as a resultant from soil contamination. The concentrations of 17 elements (As, Ba, B, Cd, Co, Cr, Cu, Fe, Hg, Li, Mo, Mn, Ni, Pb, Sb, Sr, and Zn) were measured in samples from stream sediments and surface soils. In the study area, especially geothermal and anthropogenic activities give rise to environmental pollution.     

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.     

Molecular and stable carbon isotopic compositions of saturated fatty acids within one sedimentary profile in the Shenhu,northern South China Sea: Source implications

This study examined the distributions and stable carbon isotopic compositions of saturated fatty acids (SaFAs) in one 300 cm long sedimentary profile, which was named as Site4B in Shenhu, northern South China Sea. The concentrations of total SaFAs in sediments ranged from 1.80 to 10.16 μg/g (μg FA/g dry sediment) and showed an even-over-odd predominance in the carbon chain of C₁₂ to C₃₂, mostly with n-C₁₆ and n-C₁₈ being the two major components. The short-chain fatty acids (ScFAs; n-C₁₂ to n-C₁₈) mainly from marine microorganisms had average δ¹³C values of −26.7‰ to −28.2‰, whereas some terrigenous-sourced long-chain fatty acids (LcFAs; n-C₂₁ to n-C₃₂) had average δ¹³C values of −29.6‰ to −34.1‰. The other LcFAs (n-C₂₄ & n-C₂₆ ∼ n-C₂₈; average δ¹³C values are −26.1‰ to −28.0‰) as well as n-C₁₉ and n-C₂₀ SaFAs (average δ¹³C values are −29.1‰ and −29.3‰, respectively) showed a mixed signal of carbon isotope compositions.The relative bioproductivity calculation (marine vs. terrigenous) demonstrated that most of organic carbon accumulation throughout the sedimentary profile was contributed by marine organism. The high marine productivity in Shenhu, South China Sea may be related to the hydrocarbon seepage which evidenced by diapiric structures. Interestingly, there is a sever fluctuation of terrigenous inputs around the depth of 97 cm below the seafloor (bsf), probably resulting from the influence of the Dansgaard–Oeschger events and the Younger Dryas event as revealed by ¹⁴C age measurements.