Removal of dyes from aqueous solutions using low-cost sorbents made of solid residues from olive-mill wastes (JEFT) and solid residues from refined Jordanian oil shale

The effectiveness of processed solid residue from olive-mill waste (JEFT) and solid residue of pyrolyzed oil shale in removing methylene blue as a cationic dye and methyl orange as an anionic dye from aqueous solutions has been investigated and compared with that of a commercial activated carbon, namely coconut-shell carbon. All three sorbents showed significant methylene-blue removal, but only the coconut granular-activated carbon showed notable methyl-orange removal. The oil-shale sorbent showed no removal and the olive carbon showed poor removal of methyl orange. The removal of both methylene blue and methyl orange increases with the lapse of time, and attains equilibrium in 100 min. Received: 12 May 1999 · Accepted: 1 November 1999     

Removal of selected heavy metals from MSW fly ash by the electrodialytic process

This paper aims to assess the applicability of the electrodialytic remediation technique for the removal of zinc, lead, copper and cadmium from municipal solid waste (MSW) incinerator fly ash. A broad range of experimental conditions were studied including current densities, remediation times, use of assisting agents and cell design.

Several operational problems were identified during the electrodialytic experiments, among which are formation of precipitates, dryness of sample and partial dissolution of sample creating preferential pathways for the electric current. These problems may explain the low remediation efficiencies obtained.

Comparison between experiments showed that generally the use of Na-gluconate as assisting agent leads to better results than distilled water. Increasing the concentration of the assisting agent also results in higher removals.     

Source of pollution as a factor controlling distribution of heavy metals in bottom sediments of Chechło River (south Poland)

 The influence of sources of effluents on pollution of bottom sediments of the small Chechło River (23 km long, mean discharge 1.5 m³ s^–1) in southern Poland was examined through analysis of heavy metals distribution in transverse and longitudinal cross sections. Underground waters from a Pb–Zn mine cause very high concentrations of Zn, Cd, and Pb in both fractions investigated (<1 mm and <0.063 mm) of sediments in the active channel zone, whereas sedimentation of huge amounts of suspended matter discharged from oil refinery cause concentrations of heavy metals in fine fractions rather uniform in cross sections. In the lowest reach, with relatively reduced contamination, the highest concentration both in fine and coarse fractions occurs close to the river banks and in the deepest points of the channel. The lowest concentrations have been found at the points of strongest reworking and accumulation of sandy material in the riverbed. Received: 25 April 1995 · Accepted: 11 September 1995     

Distribution of heavy metals in the Piscinas beach sediments (SW Sardinia, Italy)

We have studied sediments of the Piscinas beach (SW Sardinia, Italy), which is supplied by two streams that wash mine dumps of abandoned lead and zinc mines at Montevecchio and Ingurtosu, situated inland from the supply basin of the beach itself. A study of the texture, mineralogy and geochemistry of the sediments was conducted for the purpose of assessing the possible influence of the mine waste on the composition of the sediments, looking for any anomalous enrichments in heavy metals. Furthermore, to evaluate and quantify metal release into the sea, samples of Posidonia oceanica, a bioaccumulator marine plant, were also examined. The results indicate that the distribution of heavy metals in the foreshore sediments is particularly affected by the contribution of the streams, while in the shoreface the distribution is affected by the currents that disperse the sediments both out to sea and southwards. The metal contents of the Posidonia oceanica are correlated with the different stages of activity of the mines. Received: 28 January 1998 · Accepted: 22 April 1998     

Heavy metals in freshly deposited sediments of the Gomati River (a tributary of the Ganga River): effects of human activities

 The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river. Received: 16 February 1996 · Accepted: 29 February 1996     

Calcareous skeletons of sea urchins as indicators of heavy metals pollution. Portman Bay, Spain

 Portman Bay presents elevated quantities of metals and heavy metals in the sediments and rocky outcrops. The calcitic skeletons of the sea urchins that live there present elevated concentrations of Mn, Fe, Zn, and Pb (249, 273, 32, and 59 ppm) in comparison with control zones (beach of La Vila) where the concentrations for these elements are 5, 7, 8, and 2 ppm, respectively. Two species of sea urchins have been studied: Paracentrotus lividus and Arbacia lixula. The different compositions between the plates and the spines of their skeletons have also been studied. Received: 20 November 1995 · Accepted: 25 January 1996     

Mobilization and attenuation of heavy metals within a nickel mine tailings impoundment near Sudbury, Ontario, Canada

 The oxidation and the subsequent dissolution of sulfide minerals within the Copper Cliff tailings area have led to the release of heavy metals such as Fe, Ni, and Co to the tailings pore water. Dissolved concentrations in excess of 10 g/l Fe and 2.2 g/l Ni have been detected within the shallow pore water of the tailings, with increasing depth these concentrations decrease to or near analytical detection limits. Geochemical modelling of the pore-water chemistry suggests that pH-buffering reactions are occurring within the shallow oxidized zones, and that secondary phases are precipitating at or near the underlying hardpan and transition zones. Mineralogical study of the tailings confirmed the presence of goethite, jarosite, gypsum, native sulfur, and a vermiculite-type clay mineral. Goethite, jarosite, and native sulfur form alteration rims and pseudo-morphs of the sulfide minerals. Interstitial cements, composed of goethite, jarosite, and gypsum, locally bind the tailings particles, forming hardpan layers. Microprobe analyses of the goethite indicate that it contains up to 0.6 weight % Ni, suggesting that the goethite is a repository for Ni. Other sinks detected for heavy metals include jarosite and a vemiculite-type clay mineral which locally contains up to 1.6 weight % Ni. To estimate the mass and distribution of heavy metals associated with the secondary phases within the shallow tailings, a series of chemical extractions was completed. The experimental design permitted four fractions of the tailings to be evaluated independently. These four fractions consisted of a water-soluble, an acid-leachable, and a reducible fraction, as well as the whole-rock total. Twenty-five percent of the total mass of heavy metals was removed in the acid-leaching experiments, and 100% of the same components were removed in the reduction experiments. The data suggest that precipitation/coprecipitation reactions are providing an effective sink for most of the heavy metals released by sulfide mineral oxidation. In light of these results, potential decommissioning strategies should be evaluated with the recognition that changing the geochemical conditions may alter the stability of the secondary phases within the shallow tailings. Received: 9 April 1997 · Accepted: 21 July 1997     

Sorption behavior of heavy metal pollutants onto shales and correlation with shale geochemistry

The sorption of lead (II) and cadmium (II) on seven shales belonging to the Proterozoic Vindhyan basin, central India, and a black cotton soil, Mumbai, India, was studied and compared with sorbent geochemistry. The sorption equilibrium studies were conducted under completely mixed conditions in batch reactors (pH=5.0 and ionic strength= 0.01 M) at room temperature. The Freundlich model provided better fits to the experimental data compared to Langmuir model. High cadmium and lead sorption was observed for the calcareous shales with greater than 5% CaCO₃. The Freundlich isotherm parameter relating to sorption capacity, i.e., K_F, yielded a strong correlation with the calcium carbonate and calcium oxide content across the various geosorbents studied. The observed sorption pattern may be attributed to complex formation of CaCO₃ with Pb²⁺ and Cd²⁺ leading to surface precipitation. Moreover, the Ca²⁺ present in the sorbents may also involve in ion exchange reaction with lead and cadmium.     

Enrichment of heavy metals in paddy crops irrigated by paper mill effluents near Nanjangud, Mysore District, Karnatake, India

 Extensive irrigation by the effluents released from a paper mill near Nanjangud have led to the accumulation of heavy metals in the soil and different parts of the paddy crops. In this paper, the physicochemical characteristics of paper mill effluents and the accumulation of heavy metals (Cu, Zn, Pb, Co, Cd, Cr, and Ni) in the soil and different parts (root, leaf, and seed) of the paddy crops growing in the irrigated area are described and compared with the soil and paddy crops irrigated by natural waters (unpolluted). Chemical and biological oxygen demands of wastewater were found to be 437 and 1070 ppm respectively, which are beyond the tolerance limits set by Indian standards. The total dissolved and suspended solids are 1754 and 900 ppm respectively. The concentration of heavy metals (except Zn) in the seeds is remarkably less than that in the roots and leaves of the paddy crops. The heavy metal uptake by plants shows the greatest accumulation of Cu, Cr, Co, and Pb in the roots; Cd and Ni in the leaves; and Zn in the seeds of rice. The heavy metal content of the soil and their total uptake by paddy roots has the relation: Pb>Zn>Cu>Cd and Pb>Cu>Zn>Cd. Survival of paddy crops irrigated by polluted waters indicates tolerance to toxic heavy metals. In conclusion, since in many tropical countries the common diet of people is rice, the accumulation of toxic heavy metals in rice may lead to health disorders. Received: 18 July 1995 / Accepted: 24 February 1997     

Distribution and fractionation of heavy metals in the surface sediments of the Ganges- Brahmaputra-Meghna river system in the Bengal basin

 The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentation in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is ≤1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (I_geo) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals. The Bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution. Received: 21 July 1997 · Accepted: 13 October 1997     

Correlation between magnetic susceptibility and distribution of heavy metals in contaminated sea-floor sediments of Hong Kong Harbour

 Magnetic susceptibility measurements were conducted on 24 vibrocores obtained from an area located off the northeastern coast of Lantau Island in Hong Kong. High intensities of magnetic susceptibility were detected in the uppermost sections of the majority of the cores. Several magnetic parameters measured for one of the cores suggest that the variations in the magnetic characteristics over depth are mainly due to varying concentrations of the magnetic minerals. Since a strong correlation has been found between magnetic susceptibility and the heavy metals Pb, Cu, Zn and Cr, an anthropogenic contamination origin is thought to be the cause. The present study shows that magnetic susceptibility is a fast, inexpensive and non-destructive method for the detection and mapping of contaminated sediments. Received: 12 August 1997 · Accepted: 18 November 1997     

Testing the ability of bentonite-amended natural zeolite (clinoptinolite) to remove heavy metals from liquid waste

 The design of environmentally sound liquid waste containment structures has become a crucial task in engineering applications due to ever increasing groundwater contamination from such sites. Construction of such structures usually requires a bottom liner of low hydraulic conductivity as part of the design. In order to reduce the hazards associated with liquid wastes including landfill leachate, bentonite-amended natural zeolite is proposed as an alternative to conventional earthen liners. Among many contaminants associated with liquid wastes, heavy metals are the most dangerous ones. This paper deals with determining the ability of natural zeolite to remove heavy metals from aqueous waste. For this purpose, crushed natural zeolite (clinoptinolite) is amended with commercial powdered bentonite to yield a soil mixture low in permeability and high in ion-exchange capacity. Leachate from a conventional landfill is used as the percolation fluid. Concentrations of certain heavy metals in the effluent fluid percolated through the bentonite-zeolite mixture are compared with that of initial leachate. The conclusion is reached that certain metals are efficiently removed from the influent solution by the soil matrix whereas some ions do not show significant reduction in concentration. This is attributed to high hydraulic conductivity of the bentonite-zeolite mixture.     

Background concentrations of heavy metals in aquatic bryophytes used for biomonitoring in basaltic areas (a case study from central France)

 Studies were made of the aquatic bryophytes Fontinalis antipyretica Hedw., Platyhypnidium rusciforme (Neck.)Fleisch and Chiloscyphus sp. (Hoffm.)Dum. from streams embedded in basaltic rocks (Le Puy, central France). Water from these streams possessed elevated levels of Cu, Zn, Sr, V, Ba, Ni and Co, reflecting the geochemistry of the basalts, a basic type of igneous rocks containing elevated levels of these elements. The concentration of elements in bryophytes is correlated to the chemical composition of water of their sampling sites. Contents of trace elements in plants were higher than background values. The elevated levels of these elements possibly caused disturbances in the ionic equilibrium within the bryophytes. The molar ratio between contents of Ca and Mg in water (from 0.44 to 1) was different from that typical for natural water. Received: 16 September 1998 · Accepted: 17 December 1998     

Channel processes as a factor controlling accumulation of heavy metals in river bottom sediments: consequences for pollution monitoring (Upper Silesia, Poland)

 An evaluation of the influence of channel processes (erosion, accumulation, processing of channel sediments) on the dispersal of heavy metals in bottom sediments was carried out in the channels of the Sztoła and Biała Przemsza rivers in Upper Silesia, Poland. These rivers receive waters from a Zn and Pb mine. Mine waters transport a large amount of fine-grained sediments contaminated with heavy metals. The polluted material is accumulated in these stream courses and mixed with nearly homogeneous sandy sediment derived from erosion of the river banks and bed. Because these alluvia are easily set in motion, the distribution of heavy metal concentration in the channel in fraction <1 mm reflects differences in physical processes of sedimentation in its cross-section. The minimal values in active channel and maximal in the near-bank zone are typical for those channel sections where heavy metals, present in a solid state, are transported as a suspended load (normally the largest part of a polluted river course). In short sections heavy metals associated with the grains of a large mass which has accumulated in the active channel are transported as a bed load and the typical distribution pattern is reversed (in fractions both <1 mm and <0.063 mm). Such regularities can be disturbed in localities where strong, turbulent flow or frequent eddying occur and Mn oxides and hydrooxides and associated elements precipitate. The smallest variation in heavy metal concentration in the homogenous, fine-grained bank sediments which are trapped by plants below water level is a feature which recommends these localities as being the most suitable for monitoring of river pollution. Received: 11 November 1997 · Accepted: 12 March 1998     

The chemical and physical characteristics of heavy metals in humus and till in the vicinity of the base metal smelter at Flin Flon, Manitoba, Canada

 Trace element geochemistry of humus (<0.425 mm) and till (<0.002 mm) collected in the Flin Flon-Snow Lake area, northern Manitoba and Saskatchewan, provides a regional context for assessing smelter contamination in the environment. The area includes a Cu-Zn smelter known to discharge As, Cd, Cu, Fe, Hg, Pb, and Zn. In this study, sequential extraction analyses, scanning electron microscopy and x-ray diffraction analyses were used on a suite of samples to determine: (1) the chemical and physical characteristics of heavy metals in surficial sediments related to distance from the smelter, (2) criteria for assessing the relative contribution of these metals from natural and anthropogenic sources, and (3) the potential of these metals for remobilization in the environment. Humus geochemistry reflects the anthropogenic and natural component of heavy metal concentrations. Smelter-related elements show anomalously high values adjacent to the smelter, decreasing with distance until background values are reached at 70–104 km, depending on the element. In humus, Zn is associated primarily with labile phases; Hg with non-labile phases. Adjacent to the smelter, high proportions and concentrations of Zn and Hg in non-labile phases, indicative of smelter-derived particulates, are confirmed by SEM examination. The particles occur as spheres, irregular grains, and with organics. With increasing distance from the smelter, the geochemical response to bedrock composition is more obvious than the anthropogenic input. Till geochemistry reflects the natural variation imposed by bedrock composition. At highly contaminated sites (<3 km from the smelter), increased percentages of smelter-related elements in labile phases suggests heavy metals are leached from humus to the underlying sediment. Received: 5 November 1996 · Accepted: 31 March 1997     

Long-range atmospheric transport of trace metals: the need for geoscience perspectives

 The scientific literature of the past 25 years indicates a lack of consensus over the relative significance of anthropogenic and natural sources of metals in rural and remote ecosystems, meaning areas located several hundred to several thousand kilometers from industrial point sources. Geoscience perspectives are needed to address the critical information gaps associated with this issue, particularly where information on the significance and variability of naturally occurring metals is required. Uncertainties in source apportionment need to be addressed by improving methods of fingerprinting sources of airborne particles, and establishing identities of individual particles on the basis of characteristic morphologies and chemical composition. Further research is required to obtain robust estimates of total metal emissions to the atmosphere and to the oceans in order to determine the relative contribution from anthropogenic sources. Such research must involve a systematic attempt to obtain spatially and temporally representative data on the natural release of metals at the global scale. Moreover, a clear understanding of all local natural and anthropogenic loadings to an ecosystem is required before firm conclusions can be drawn about the relative importance of long-range atmospheric transport. Received: 31 October 1996 · Accepted: 27 May 1997     

Stable isotopes and heavy metal distribution in Dreissena polymorpha (Zebra Mussels) from western basin of Lake Erie, Canada

 Dreissena polymorpha is an exotic freshwater bivalve species which was introduced into the Great Lakes system in the fall of 1985 through the release of ballast water from European freighters. Utilizing individual growth rings of the shells, the stable isotope distribution (δ¹⁸O and δ¹³C) was determined for the life history of selected samples which were collected from the western basin of Lake Erie. These bivalves deposit their shell in near equilibrium with the ambient water and thus reflect any annual variation of the system in the isotopic records held within their shells. Observed values for δ¹⁸O range from -6.64 to –9.46‰ with an average value of –7.69‰ PDB, while carbon values ranged from –0.80 to –4.67‰ with an average value of –1.76‰ PDB. Dreissena polymorpha shells incorporate metals into their shells during growth. Individual shell growth increments were analyzed for Pb, Fe, Mg, Mn, Cd, Cu, and V concentrations. The shells show increased uptake of certain metals during periods of isotopic enrichment which correspond with warmer water temperatures. Since metals are incorporated into the shells, the organism may be useful as a biomonitor of metal pollution within aquatic environments. Received: 31 October 1996 · Accepted: 21 May 1997     

Accumulation of muds and metals in the Hudson River estuary turbidity maximum

 In the Hudson River estuary, fine mud and toxic metals are enriched in the upstream turbidity maximum. The mechanisms causing the enrichment were assessed through the analysis of suspended-sediment concentration (SSC) (bottom and surface), particle size, and trace metal distributions. Bottom SSCs varied across the study area by a factor of ten, and the turbidity maximum activity was observed in between kilometers 45 and 80. The particle-size analysis defined two accumulation modes: <4.65 and >22.1 μm. The ratio of the fine-to-coarse mode increased from 1.75 to 2.75 in the turbidity maximum. The fine mud concentration (55–60%) in the turbidity maximum was found to have a high correlation (r=0.98;p<0.005) with the concentration of <2-μm particles. A conceptual model was derived in order to understand the possible mechanisms by which fine mud (and specifically <2-μm particles) is concentrated. The two dominant size modes were analyzed for toxic metals. The upstream tributaries are major sources of metals compared to point sources at downstream locations. In the turbidity maximum, Cd, Cu, Zn, and Pb are significantly enriched compared to average shale metal values and ERM toxicity guidelines by 580, 42, 10, 16 and 12, 7, 2.4, 1.4 times, respectively. Decreasing metal concentrations downstream of the turbidity maximum imply that Haverstraw Bay acts as temporary storage for fine particles and enriched metals. It is demonstrated in this study that toxic metals are enriched in Haverstraw Bay due to the mud accumulation. The high levels of toxic metals in the sediments of the Hudson River estuary are a major concern because human activities (dredging and river traffic) cause resuspension of sediments and can change the mobility patterns of bioavailable contaminants. Received: 4 June 1997 · Accepted: 9 September 1997     

Natural and anthropogenic influences on the geochemistry of Quaternary lake sediments from Holzmaar, Germany

 The accumulation of heavy metals and trace elements has been investigated in a well laminated sequence of Holocene and late Pleistocene lake sediments composed of diatomaceous gyttja, tuff and silt and clay sediments. Varve chronology of the annually deposited gyttja yielded a continuous high-resolution time sequence and allowed the absolute age dating of the sediment. Fluxes of elements remained largely uniform from the late Pleistocene into the Holocene (12 867–2 364 VT years ago; VT: varve time, years before 1950). Higher trace element and heavy metal fluxes occur from 2 322 to 862 VT years ago and reached their maxima in the uppermost sediments (<845 VT years ago). These increasing element fluxes correlate with increasing inputs of clastic material. The changing accumulation rates are the result of elevated soil erosion in the lake catchment caused by human settlement, deforestation and agricultural activities. Thus disturbances of the natural geochemical cycles of the Holzmaar region have occurred since the beginning of the Iron Age and especially since the beginning of the Middle Ages. Received: 29 May 1996 · Accepted: 19 August 1996