Heavy metals in the surficial sediments of Fontana Lake, North Carolina

Concern about the possible contamination by heavy metals of Fontana Lake (reservoir) and potential sources of such materials led to a study of surficial sediments. Samples of sediment were collected in the main body of the lake and near the mouths of its major tributaries and analayzed for magnesium, iron, aluminum, manganese, zinc, copper and mercury. Although the drainage area of the reservoir is primarily forested and rural without major industrial developments, the results indicated that manganese, copper and zinc were present in concentrations similar to areas receiving industrial pollution. Chemical analyses of pyritic materials in the watershed (e.g. schists or Anakeesta formation) showed relatively high concentrations of many of the same metals present in Fontana sediments. It appears, therefore, that the metals in the lake sediments represent materials derived from geological sources, although airborne contributions of certain metals cannot be ruled out.     

Short-term variations in the occurrence of heavy metals in Antarctic snow from Coats Land since the 1920s

Short-term variations in heavy metals concentrations in Antarctic snow have been investigated by analysing 13 metals (Al, V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi and U) in a series of ultraclean samples collected from two snow pits in Coats Land in the Atlantic sector of Antarctica. The samples covered a approximately 70 years time period from the 1920s to 1990. They were analysed by inductively coupled plasma sector field mass spectrometry and graphite furnace atomic absorption spectrometry. The results conclusively show that there is a pronounced short-term (intra- and inter-annual) variability of heavy metal in Antarctic snow, with the highest concentrations being up to 100 times higher than the lowest ones for metal such as Cr, Mn, Pb and U. Contributions from the different possible natural and anthropogenic sources are found to be extremely variable. This is especially due to the large variability in the transport patterns of heavy metals from Southern America, Southern Africa and Australia to the Antarctic continent. Inputs from several volcanic events were identified in our samples from non-seasalt sulfate concentrations profiles. The only ones that gave clear signals for heavy metals were eruptions at Deception Island the proximity of which allowed for tropospheric transport to Coats Land.     

Environmental modelling in the Gulf of Cadiz: Heavy metal distributions in water and sediments

The Gulf of Cadiz (GoC) connects the Atlantic Ocean and the Mediterranean Sea. An environmental study of the GoC is carried out through numerical modelling. First, a 3D baroclinic model is used to obtain the residual circulation and a 2D barotropic model is applied to calculate tides. The results of these models are used by a 3D sediment transport model which provides suspended matter concentrations and sedimentation rates in the GoC. Then heavy metal dispersion patterns are investigated using a 3D model which includes water-sediment metal interactions and uses the outputs of the hydrodynamic and sediment transport models. The metal transport model has been applied to simulate the dispersion of Zn, Cu and Ni introduced into the GoC from three rivers draining the Iberian Pyrite Belt, in the southern Iberian Peninsula. Results from the hydrodynamic, sediment and metal transport models have been compared with measurements in the GoC. In particular, the contamination of sediments collected along the southern coast of Spain is well reproduced by the model. Metal plumes reach the Strait of Gibraltar, thus the three rivers constitute a source of pollutants into the Mediterranean Sea.     

Heavy metals in urban soils: a case study from the city of Palermo (Sicily), Italy

Concentrations of V, Mn, Cd, Zn, Ni, Cr, Co, Cu, Pb, Hg and Sb were measured on 70 topsoil samples collected from green areas and parks in the city of Palermo (Sicily) in order to: (1) assess the distribution of these heavy metals in the urban environment; (2) discriminate natural and anthropic contributions; and (3) identify possible sources of pollution. Mineralogy, physico-chemical parameters, and major element contents of the topsoils were determined to highlight the influence of 'natural' features on the heavy metal concentrations and their distribution. Medians of Pb, Zn, Cu and Hg concentrations of the investigated urban soils are 202, 138, 63 and 0.68 mgkg(-1), respectively. These values are higher, in some case by different orders of size, than those of unpolluted soils in Sicily that average 44, 122, 34 and 0.07 mg kg(-1). An ensemble of basic and multivariate statistical analyses (cluster analysis and principal component analysis) was performed to reduce the multidimensional space of variables and samples, thus defining two sets of heavy metals as tracers of natural and anthropic influences. Results demonstrate that Pb, Zn, Cu, Sb and Hg can be inferred to be tracers of anthropic pollution, whereas Mn, Ni, Co, Cr, V and Cd were interpreted to be mainly inherited from parent materials. Maps of pollutant distribution were constructed for the whole urban area pointing to vehicle traffic as the main source of diffuse pollution and also showing the contribution of point sources of pollution to urban topsoils.     

Heavy metal mobility in intertidal sediments of the Scheldt estuary: Field monitoring

The current paper aims to check whether the factors affecting metal mobility in intertidal sediments and floodplain soils of the river Scheldt, as identified under controlled greenhouse conditions in previous studies, also play a similar role under variable field conditions. Moreover, we aimed to assess the importance of these factors as a function of sampling time and depth, with respect to the natural variations in water table levels. This field monitoring revealed that the mobility of metals in intertidal sediments of the Scheldt estuary indeed are affected by factors which were identified to affect the metal fate in the upper sediment layer in previous greenhouse experiments. However, the effects were often less pronounced under field conditions. This can be attributed to the lower sampling resolution, the occurrence of interactions between factors, the disturbance of microbial communities during setup of greenhouse experiments and the more moderate environmental conditions in the field, affecting microbial and enzymatic activities. At most of the sampled wetlands, the level of the water table fluctuated only slightly during fall, winter and spring, whereas it decreased substantially during summer, especially at the sites with more sandy sediments. The highest sulphide concentrations were found at the sites where the water table level never decreased considerably. These sulphides primarily suppress the availability of Cd, Cu, Ni and Zn. Organic complexation resulted in the mobilisation of Cu, Ni and Cr. The concentrations of Cd, Ni and Zn in the pore water were affected by Fe/Mn oxide reduction, whereas Cd and Zn concentrations appeared to be also affected by the salinity.     

Heavy metals in domestic wastewater with respect to urban population in Ostrava,Czech Republic

During dry weather periods, domestic wastewater is a major component of urban wastewater influent to a wastewater treatment plant (WWTP). For this reason, the quantity and quality of domestic wastewater have a considerable effect on the resultant contamination of urban wastewater and on the subsequent selection of appropriate WWTP technology. The aim of this study was to quantify the amount of hazardous elements in domestic wastewater to determine the average daily production of domestic wastewater and risk elements per inhabitant and quantify the proportion of households in the total load of urban wastewater. Wastewater samples were collected from nine local sewer systems in Ostrava, the Kravare WWTP and the Central Wastewater Treatment Plant of Ostrava (Czech Republic). We found that the average production of wastewater from households is approximately 135 L per person per day. The results also show that the share of households in urban wastewater is approximately 60% in the case of Cd, 35–21% in the case of Zn, Cu, As and less than 15% for Pb, Cr, Fe, Ni and Mn.     

Heavy metals extraction by microemulsions

The objective of this study is the heavy metal extraction by microemulsion, using regional vegetable oils as surfactants. Firstly, the main parameters, which have influence in the microemulsion region, such as: nature of cosurfactant, influence of cosurfactant (C)/surfactant (S) ratio and salinity were studied, with the objective of choosing the best extraction system. The extraction/reextraction process by microemulsion consists of two stages. In the first one, the heavy metal ion present in the aqueous phase is extracted by the microemulsion. In a second step, the reextraction process occurs: the microemulsion phase, rich in metal, is acidified and the metal is recovered in a new aqueous phase, with higher concentration. The used system had the following parameters: surfactant-saponified coconut oil; cosurfactant-n-butanol; oil phase-kerosene; C/S ratio=4; salinity-2% (NaCl); temperature of 27+/-1 degrees C; water phase-aqueous solution that varied according to the heavy metal in study (Cr, Cu, Fe, Mn, Ni and Pb). A methodology of experimental planning was used (Scheffé Net) to study the behavior of the extraction in a chosen domain. The extraction was accomplished in one step and yielded extraction percentage higher than 98% for all metals. In the reextraction HCl-8M was used as reextraction agent and the influence of the pH and time were verified. This work showed the great efficiency of the microemulsion, indicating that it is possible to extract selectively the heavy metals from the aqueous phase.     

Mobile and bound forms of trace metals in sediments of the lower ganges

Mobile and bound trace metals associated with sediment components (viz. exchangeable, carbonate, organic, Fe/Mn oxide and residual fractions) were determined at five locations on the River Ganges in the lower reaches. In the exchangeable phase, 5–22% of Pb, 5–14.4% of Cr, 3–16.4% of Cd, 3–16% of Zn and 1–13.5% of Cu were found, and in the carbonate phase 73–87% of Zn, 38–41% of Cd, 13–27% of Ni and 3–10.1% of Pb were found. The Fe/Mn oxide phase retained about 79–83% of Mn, 30–40% of Cr and Fe, 22–25% of Cu, 14–16% of Ni and 9–11% of Pb. In the organic phase about 36–47% of Cd, 22–28% of Cu and 10–15% of Pb were found. The order of release of metals was Cd > Cr > Pb > Cu > Zn > Ni > Mn > Fe, and the order of adsorption characteristics of most of the mobile metal fractions was Fe/Mn oxide > organic > clay. Correlations of the physico-chemical parameters with adsorption characteristics were also determined and a good correlation (r = 0.7) of cation exchange capacity with the clay fraction was found. I_geo (geoaccumulation indices) of metals in the sediments were also evaluated. Results showed a considerable enrichment of trace metals in the sediment phase at almost all the sites.     

Metal content of charcoal in mining-impacted wetland sediments

Charcoal is well known to accumulate contaminants, but its association with metals and other toxic elements in natural settings has not been well studied. Association of contaminants with charcoal in soil and sediment may affect their mobility, bioavailability, and fate in the environment. In this paper, natural wildfire charcoal samples collected from a wetland site that has been heavily contaminated by mine waste were analyzed for elemental contents and compared to the surrounding soil. Results showed that the charcoal particles were enriched over the host soils by factors of two to 40 times in all contaminant elements analyzed. Principal component analysis was carried out on the data to determine whether element enrichment patterns in the soil profile charcoal are related to those in the soils. The results suggest that manganese and zinc concentrations in charcoal are controlled by geochemical processes in the surrounding soil, whereas the concentrations of arsenic, lead, zinc, iron, phosphorus, and sulfur in charcoal are unrelated to those in the surrounding soil. This study shows evidence that charcoal in soils can have a distinct and important role in controlling contaminant speciation and fate in the environment.     

The influence of spent household batteries to the organic fraction of municipal solid wastes during composting

The objective of this work was to investigate the potential transfer of 9 heavy metals from spent household batteries (zinc-carbon and alkaline-manganese batteries) to the organic fraction of municipal solid wastes during active composting. Six runs were performed including one control and 2 replications. Eleven types of alkaline and non-alkaline batteries were added at 3 different levels to the organic fraction of municipal solid wastes, namely at percentages equal to 0.98% w/w (low), 5.2% w/w (medium) and 10.6% w/w (high). Experiments were performed in 230 l insulated plastic aerobic bioreactors under a dynamic air flow regime for up to 60 days. Iron, copper and nickel masses contained in the organic fraction of the wastes were found significantly higher in the high level runs compared to the corresponding masses in the control. No metal transfer was obtained in the low and medium level runs. Metal mass balance closures ranged from 51% to 176%. Metals' concentrations in the leachates were below 10 mg l⁻¹ for most metals, except iron, while an increasing concentration trend versus time was measured in the leachates of the high level runs. In all cases, the contents of 5 regulated heavy metals in all end products were below the Hellenic limits.     

Heavy metals in drilling‐waste leachates from East Java,Indonesia

This study examined the leaching toxicity characteristics of heavy metals in drilling‐waste mud by the toxicity characteristic leaching procedure (TCLP). Ten heavy metal elements As, Ba, Cd, Cr, Cu, Pb, Se, Ag, Zn and Hg were investigated. Test drilling‐waste mud samples were collected from eight active exploration wells. The TCLP results showed that the concentrations of the metals were below the Indonesian Regulatory Standards Nos. 18 and 85 (1999) regarding hazardous waste management. Barium was detected in all the leachates, and ranged from 0.40 to 6.59 mg/l. Mercury was below detectable levels at only two stations. Values of the other metals varied significantly from one station to another.     

Size charge fractionation of metals in municipal solid waste landfill leachate

Municipal solid waste landfill leachates from 9 Norwegian sites were size charge fractionated in the field, to obtain three fractions: particulate and colloidal matter >0.45microm, free anions/non-labile complexes <0.45microm and free cations/labile complexes <0.45microm. The fractionation showed that Cd and Zn, and especially Cu and Pb, were present to a large degree (63-98%) as particulate and colloidal matter >0.45microm. Cr, Co and Ni were on the contrary present mostly as non-labile complexes (69-79%) <0.45microm. The major cations Ca, Mg, K, and Mn were present mainly as free cations/labile complexes <0.45microm, while As and Mo were present to a large degree (70-90%) as free anions/non-labile complexes <0.45microm. Aluminium was present mainly as particulate and colloidal matter >0.45microm. The particulate and colloidal matter >0.45microm was mainly inorganic; indicating that the metals present in this fraction were bound as inorganic compounds. The fractionation gives important information on the mobility and potential bioavailability of the metals investigated, in contrast to the total metal concentrations usually reported. To study possible changes in respective metal species in leachate in aerated sedimentation tanks, freshly sampled leachate was stored for 48h, and subsequently fractionated. This showed that the free heavy metals are partly immobilized during storage of leachate with oxygen available. The largest effects were found for Cd and Zn. The proportion of As and Cr present as particulate matter or colloids >0.45microm also increased.     

Carbon and nitrogen stable isotopes and metal concentration in food webs from a mining-impacted coastal lagoon

Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher delta(15)N values and lower delta(13)C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by delta(15)N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the "handle strategy" of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but also from adsorption over the body surfaces and seawater ingestion.     

Heavy metals in maternal and cord blood

Heavy metal concentrations have been determined in maternal and cord blood samples collected from mothers in the age group 20-25 years with full-term neonates (37-40 weeks). The concentrations of Pb, Cd, Cu and Zn were found to be low in cord blood as compared to mother's blood and the ratio between cord blood and maternal blood for the respective elements was found to be approximately 0.80, 0.86, 0.47 and 0.40. On the other hand, the concentrations of Fe and Mg in the mother's blood were found to be lower than those in the cord blood. Prenatal exposure to lead in Mumbai, though low (5.1 microg/dl), is approximately 2-3 times higher than that observed in Canada or Italy. A strong correlation (r = 0.79) between the maternal and cord blood lead levels has been observed during the present study.     

Heavy metal pollution status in surface sediments of the coastal Bohai Bay

Bohai Bay, the second largest bay of Bohai Sea, largely due to the huge amount of pollutants discharged into it annually and its geohydrologic condition, is considered to be one of the most polluted marine areas in China. To slow down, halt and finally reverse the environmental deterioration of Bohai Sea, some researchers have proposed to connect it with Jiaozhou Bay in the western coast of Southern Yellow Sea by digging an interbasin canal through Shandong Peninsula. In order to assess the heavy metal pollution and provide background information for such a large geoengineering scheme, surface sediments from 42 stations covering both riverine and marine regions of the northwestern coast of Bohai Bay were analyzed for heavy metal content and fractionation (Cd, Cr, Cu, Ni, Pb and Zn). Three empirically derived sediment quality guidelines were used to assess the pollution extent of these metals. The studied metals had low mobility except for Cd at all stations and Zn at some riverine stations. Although a high mobility of Cd was observed, it could hardly cause a bad effect on the environment owing to its low total concentrations. Anthropogenic influence on the accumulation of studied heavy metals in sediments of Bohai Bay was obvious, but their contents were relatively lower to date comparing with some other marine coastal areas that receive important anthropogenic inputs. Taking as a whole, surface sediments of northwestern Bohai Bay had a 21% probability of toxicity based on the mean effects range-median quotient.     

The effect of tidal heights on the distribution and abundance of coliform bacteria in the sediments of two sites in the Mersey Estuary

An investigation of the tidal factors controlling the abundance and distribution of coliform bacteria in the sediments of two intertidal sites in the River Mersey (U.K.) was made during 1976. Samples were collected, at approximately weekly intervals, from September to December. Counts of the total coliform, faecal coliform and E. coli type I, were made in order to relate the numbers of bacteria to the salinity conditions of the tidal waters covering the sites. Correlations were observed between coliform counts, chloride content and tidal heights.     

碳化对水泥制品中重金属元素溶出性能的影响研究

采用3种工业废弃物,配制水泥净浆试件,对比研究了标准养护和碳化作用条件下,水泥制品中重金属元素的溶出性能经时变化规律,分析了碳化作用对重金属溶出的影响机理。结果表明,重金属的溶出符合Fick扩散第二定律;溶出主要发生在前14 d,而后趋于平缓,21 d后溶出量极少;工业废弃物的重金属含量会显著影响其平均扩散系数和总溶出量。水泥基材料的高碱性环境、致密的孔隙结构以及稳定的水化产物形态是重金属元素稳定固化的重要保障,碳化由表及里地降低了材料的碱度和密实度,引起大部分水化产物分解,使得碳化作用后水泥试件的重金属溶出量和平均扩散系数增加。     

Heavy metal behaviour in peat - A mineralogical perspective

The mineralogical composition of a 40 cm subsurface layer of transitional mire ‘Bagno Bruch’ (southern Poland) polluted with atmospheric dust was studied using scanning electron microscopy. The mire is located 9 km to the east of a zinc smelter on the northern limit of industrial Upper Silesia in southern Poland. Concentrations of zinc, lead and cadmium reach values of 494, 238 and 16 mg kg⁻¹, respectively, in the peat layer.Inorganic particles in the peat were grouped into two main categories based on their origin: air dust particles of anthropogenic- and natural sources, and authigenic minerals that originated within the mire. Anthropogenic particles comprise an important part of the inorganic particles in the peat. As they are typically enriched in heavy metals, their stability is critical to controlling metal mobilities. Spheroidal aluminosilicate fly-ash particles are the most common- and most stable anthropogenic pollutants. Partially dissolved Pb-bearing particles (sulphides, chlorides and oxides) and ZnS occur as trace components throughout the peat profile. The prolonged existence of the particles made them susceptible to gravitational relocation in the peat and limits the biogeochemical cycling of the constituent elements. The least resistant Fe (hydro)oxides release Zn and minor amounts of Mn, Mg and Sn due to reductive dissolution. The released Zn is immobilized in the form of ZnS spherules, 1-3 μm in diameter, approximately 10 cm further down in the profile.The investigation shows that the behaviour of trace elements in polluted peatland is controlled by mineral dissolution/precipitation processes. The formation of authigenic minerals (ZnS, barite, gypsum) indicates complex redox conditions and element redistribution in the transitional mire.     

The vertical distribution of some heavy metals in three recent sediment cores from the Western Nigerian continental shelf

Results of trace metal analyses of three shallow sediment cores from the Nigerian continental shelf show homogeneities with respect to the vertical distributions of Pb, Ni, Cr and Cu. However, surface enrichment of heavy metals which results from human activities particularly, from Lagos city, is recognised in the uppermost few centimeters in core 12 nearest to the entrance of Lagos harbour. Sediments below this surface enrichment zone, and in the entire lengths of the other two cores which are situated farther east of Lagos port, show heavy metal contents that are more or less constant in vertical distribution with depth.     

The behaviour of pharmaceuticals and heavy metals during struvite precipitation in urine

Separating urine from wastewater at the source reduces the costs of extensive wastewater treatment. Recovering the nutrients from urine and reusing them for agricultural purposes adds resource saving to the benefits. Phosphate can be recovered in the form of struvite (magnesium ammonium phosphate). In this paper, the behaviour of pharmaceuticals and heavy metals during the precipitation of struvite in urine is studied.When precipitating struvite in urine spiked with hormones and non-ionic, acidic and basic pharmaceuticals, the hormones and pharmaceuticals remain in solution for more than 98%.For heavy metals, initial experiments were performed to study metal solubility in urine. Solubility is shown to be affected by the chemical conditions of stored and therefore hydrolysed urine. Thermodynamic modelling reveals low or very low equilibrium solute concentrations for cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb). Experiments confirmed Cd, Cu and Pb carbonate and hydroxide precipitation upon metal addition in stored urine with a reaction half-life of ca. 7 days.For all metals considered, the maximum specific metal concentrations per gram phosphate or nitrogen showed to be typically several orders of magnitudes lower in urine than in commercially available fertilizers and manure. Heavy metals in struvite precipitated from normal stored urine could not be detected.Phosphate recovery from urine over struvite precipitation is shown to render a product free from most organic micropollutants and containing only a fraction of the already low amounts of heavy metals in urine.