Cu and Zn adsorption onto non-residual and residual components in the natural surface coatings samples (NSCSs) in the Songhua River, China

Natural surface coatings samples (NSCSs) from the surface of river shingles were employed to investigate the roles of non-residual and residual components of the NSCSs in controlling Cu and Zn adsorption via the selective extraction techniques and statistical analysis. The results indicate that the greatest contribution to metals adsorption on a molar basis was from Mn oxides in the non-residual fraction. Metals adsorption capacities of Mn oxides exceeded those of Fe oxides by one order of magnitude, fewer roles were found attributing to adsorption by organic materials (OM), and the estimated contribution of the residual fraction to metals adsorption was insignificant. These results implied that Mn oxides were the most important component in controlling heavy metals in aquatic environments. Experiments with Cu and Zn adsorption measured together showed that Cu severely interfered with Zn adsorption to the NSCSs and vice versa under the conditions of the two coexisted ions adsorption.     

Agricultural solid waste for sorption of metal ions,part II: competitive assessment in multielemental solution and lake water

Sugarcane bagasse and hydroponic lettuce roots were used as biosorbents for the removal of Cu(II), Fe(II), Mn(II), and Zn(II) from multielemental solutions and lake water, in batch processes. These biomasses were studied in natura (lettuce roots, NLR, and sugarcane bagasse, NSB) and chemically modified with HNO₃ (lettuce roots, MLR, and sugarcane bagasse, MSB). The results showed higher adsorption efficiency for MSB and either NLR or MLR. The maximum adsorption capacities (q_max) in multielemental solution for Cu(II), Fe(II), Mn(II), and Zn(II) were 35.86, 31.42, 3.33, and 24.07 mg/g for NLR; 25.36, 27.95, 14.06, and 6.43 mg/g for MLR; 0.92, 3.94, 0.03, and 0.18 mg/g for NSB; and 54.11, 6.52, 16.7, and 1.26 mg/g for MSB, respectively. The kinetic studies with chemically modified biomasses indicated that sorption was achieved in the first 5 min and reached equilibrium around 30 min. Sorption of Cu(II), Fe(II), Mn(II), and Zn(II) in lake water by chemically modified biomasses was 24.31, 14.50, 8.03, and 8.21 mg/g by MLR, and 13.15, 10.50, 6.10, and 5.14 mg/g by MSB, respectively. These biosorbents are promising and low costs agricultural residues, and as for lettuce roots, these showed great potential even with no chemical modification.     

Agricultural solid waste for sorption of metal ions: part I—characterization and use of lettuce roots and sugarcane bagasse for Cu(II), Fe(II), Zn(II), and Mn(II) sorption from aqueous medium

Sugarcane bagasse and hydroponic lettuce roots were used as biosorbents for Cu(II), Fe(II), Zn(II), and Mn(II) removal from monoelemental solutions in aqueous medium, at pH 5.5, using batch procedures. These biomasses were studied in natura (lettuce roots, NLR, and sugarcane bagasse, NSB) and modified with HNO₃ (lettuce roots, MLR, and sugarcane bagasse, MSB). Langmuir, Freundlich, and Dubinin-Radushkevich non-linear isotherm models were used to evaluate the data from the metal ion adsorption assessment. The maximum adsorption capacities (q_max) in monoelemental solution, calculated using the Langmuir isothermal model for Cu(II), Fe(II), Zn(II), and Mn(II), were respectively 24.61, 2.64, 23.04, and 5.92 mg/g for NLR; 2.29, 16.89, 1.97, and 2.88 mg/g for MLR; 0.81, 0.06, 0.83, and 0.46 mg/g for NSB; and 1.35, 2.89, 20.76, and 1.56 mg/g for MSB. The Freundlich n parameter indicated that the adsorption process was favorable for Cu(II) uptake by NLR; Fe(II) retention by MLR and MSB; and Zn(II) sorption by NSB, MLR, and NSB and favorable for all biomasses in the accumulation of Mn(II). The Dubinin-Radushkevich isotherm was applied to estimate the energy (E) and type of adsorption process involved, which was found to be a physical one between analytes and adsorbents. Organic groups such as O–H, C–O–C, CH, and C=O were found in the characterization of the biomass by FTIR. In the determination of the biomass surface charges by using blue methylene and red amaranth dyes, there was a predominance of negative charges.     

Mobility of heavy metals from polluted sediments of a semi-enclosed basin: in situ benthic chamber experiments in Taranto’s Mar Piccolo (Ionian Sea,Southern Italy)

In situ benthic flux experiments were conducted at two stations in the Mar Piccolo of Taranto (Italy), one of the most industrialised and contaminated coastal areas of the Mediterranean. Sediments of the two stations are notably different in their trace metal content, with a station closer to a Navy harbour showing higher mean concentrations of almost all investigated metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn). Conversely, both stations are characterised by significant Hg contamination, compared to the local baseline. Results of a sequential extraction scheme on surface sediments suggest a relatively scarce mobility of the examined metals (Zn > Ni > Cr > As > Cu > Pb). A Hg-specific extraction procedure showed that most of the element (93.1 %) occurs in a fraction comprising Hg bound to Fe/Mn oxi-hydroxides. Reduction of these oxides may affect Hg remobilisation and redistribution. Porewater profiles of dissolved trace metals were quite similar in the two sites, although significant differences could be observed for Al, Cu, Fe and Hg. The highest diffusive fluxes were observed for As, Fe and Mn. Mobility rates of several trace elements (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn) were directly measured at the sediment–water interface. Results from benthic in situ incubation experiments showed increasing dissolved metal concentrations with time, resulting in higher fluxes for Cu, Fe, Hg, V and Zn in the most contaminated site. Conversely, fluxes of Mn, Ni and Pb were comparable between the two stations. The estimated flux of Hg (97 μg m^?2 day^?1) was the highest observed among similar experiments conducted in other highly contaminated Mediterranean coastal environments. Benthic fluxes could be partially explained by considering rates of organic matter remineralisation, dissolution of Fe/Mn oxy-hydroxides and metal speciation in sediments. Seasonal and spatial variation of biogeochemical parameters can influence metal remobilisation in the Mar Piccolo area. In particular, metals could be promptly remobilised as a consequence of oxygen depletion, posing a serious concern for the widespread fishing and mussel farming activities in the area.     

Trace metals in Ganges soft-shell turtle (Aspideretes gangeticus) from two barrage: Baloki and Rasul, Pakistan

The concentration of nine metals was measured in liver, kidney, heart, muscle, plastron, and carapace of Aspideretes gangeticus from Rasul and Baloki barrages, Pakistan. The results indicated that metal concentration were significant different among tissues of Ganges soft-shell turtles. However, higher concentrations of Co (5.12 μg/g) and Ni (1.67 μg/g) in liver, Cd (0.41 μg/g) in heart, Fe (267.45 μg/g), Cd (2.12 μg/g) and Mn (2.47 μg/g) in kidney, Cd (0.23 μg/g), Cu (2.57 μg/g), Fe (370.25 μg/g), Mn (5.56 μg/g), and Pb (8.23 μg/g) in muscle of A. gangeticus were recorded at Baloki barrage than Rasul barrage. Whereas mean concentrations of Pb (3.33 μg/g) in liver, Co (1.63 μg/g), Cu (11.32 μg/g), Pb (4.8 μg/g) and Zn (144.69 μg/g) in heart, Co (4.12 μg/g) in muscle, Ni (1.31 μg/g), Pb (2.18 μg/g), and Zn (9.78 μg/g) in carapace were recorded higher at Rasul barrage than Baloki barrage. The metals followed the trend Fe > Zn > Ni > Cu > Mn > Pb > Cr > Co > Cd. Metals of toxicological concern such as Cr, Pb, and Cd were at that level which can cause harmful effects to turtles. The results provide baseline data of heavy metals on freshwater turtle species of Pakistan.     

Accumulation and fractionation of copper, iron, manganese, and zinc in calcareous soils amended with composts.

Amending soils with compost may lead to accumulation of metals and their fractions at various concentrations in the soil profile. The objectives of this study were to determine 1) the accumulation of Cu, Fe, Mn, and Zn with depth and 2) the distribution of water soluble, exchangeable, carbonate, Fe-Mn oxides, organic and residual forms of each metal in soils amended with MSW compost, co-compost, biosolids compost and inorganic fertilizer (as control). Total concentrations of Cu, Fe, Mn and Zn were concentrated in the 0-22 cm soil layer and scant in the rock layer. These metals were in the decreasing order of Fe > Mn > Zn > or = Cu. Copper, Fe, and Zn were predominantly in the residual form followed by fractions associated with Fe-Mn oxides, carbonate, organic, exchangeable and water soluble in all treatments except MSW compost amended soil where the organic fraction was higher than the carbonate fraction. In fertilizer, co-compost and biosolids compost treated soils Mn concentrated mainly in the Fe-Mn oxides form followed by residual, carbonate, and organic forms whereas, in MSW compost treated soil the same pattern occurred except that Mn organic fraction was higher than that in the carbonate form. The MSW compost has a greater potential to be used as a soil amendment to supply plants with Cu, Mn and Zn than other treatments in calcareous soils of south Florida.     

Distribution of potentially toxic elements (PTEs) in tailings,soils, and plants around Gol-E-Gohar iron mine,a case study in Iran

This study investigated the concentration of potentially toxic elements (PTEs) including Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, V, and Zn in 102 soils (in the Near and Far areas of the mine), 7 tailings, and 60 plant samples (shoots and roots of Artemisia sieberi and Zygophylum species) collected at the Gol-E-Gohar iron ore mine in Iran. The elemental concentrations in tailings and soil samples (in Near and Far areas) varied between 7.4 and 35.8 mg kg^?1 for As (with a mean of 25.39 mg kg^?1 for tailings), 7.9 and 261.5 mg kg^?1 (mean 189.83 mg kg^?1 for tailings) for Co, 17.7 and 885.03 mg kg^?1 (mean 472.77 mg kg^?1 for tailings) for Cu, 12,500 and 400,000 mg kg^?1 (mean 120,642.86 mg kg^?1 for tailings) for Fe, and 28.1 and 278.1 mg kg^?1 (mean 150.29 mg kg^?1 for tailings) for Ni. A number of physicochemical parameters and pollution index for soils were determined around the mine. Sequential extractions of tailings and soil samples indicated that Fe, Cr, and Co were the least mobile and that Mn, Zn, Cu, and As were potentially available for plants uptake. Similar to soil, the concentration of Al, As, Co, Cr, Cu, Fe, Mn, Mo, Ni, and Zn in plant samples decreased with the distance from the mining/processing areas. Data on plants showed that metal concentrations in shoots usually exceeded those in roots and varied significantly between the two investigated species (Artemisia sieberi > Zygophylum). All the reported results suggest that the soil and plants near the iron ore mine are contaminated with PTEs and that they can be potentially dispersed in the environment via aerosol transport and deposition.     

Removal of Pb(II), Cd(II), Cu(II), and Zn(II) by hematite nanoparticles: effect of sorbent concentration, pH, temperature, and exhaustion

Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions (Pb(II), Cd(II), Cu(II), Zn(II)) to nanohematite was examined as a function of sorbent concentration, pH, temperature, and exhaustion. Adsorption experiments were conducted with 0.05, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water. The adsorption data showed the ability of nanohematite to remove Pb, Cd, Cu, and Zn species from solution with adsorption increasing as the nanoparticle concentration increased. At 0.5 g/L nanohematite, 100 % Pb species adsorbed, 94 % Cd species adsorbed, 89 % Cu species adsorbed and 100 % Zn species adsorbed. Adsorption kinetics for all metals tested was described by a pseudo second-order rate equation with lead having the fastest rate of adsorption. The effect of temperature on adsorption showed that Pb(II), Cu(II), and Cd(II) underwent an endothermic reaction, while Zn(II) underwent an exothermic reaction. The nanoparticles were able to simultaneously remove multiple metals species (Zn, Cd, Pb, and Cu) from both a pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that at pH 8, exhaustion did not occur for the nanoparticles but adsorption does decrease for Cd, Cu, and Zn species but not Pb species. The strong adsorption coupled with the ability to simultaneously remove multiple metal ions offers a potential remediation method for the removal of metals from water.     

Concentration and health risk evaluation of heavy metals in market-sold vegetables and fishes based on questionnaires in Beijing,China

Concentrations of heavy metals (As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn) in market vegetables and fishes in Beijing, China, are investigated, and their health risk to local consumers is evaluated by calculating the target hazard quotient (THQ). The heavy metal concentrations in vegetables and fishes ranged from not detectable (ND) to 0.21 mg/kg fresh weight (f.w.) (As), ND to 0.10 mg/kg f.w. (Cd), and n.d to 0.57 mg/kg f.w. (Pb), with average concentrations of 0.17, 0.04, and 0.24 mg/kg f.w., respectively. The measured concentrations of As, Cd, Pb, Cu, Ni, Fe, Mn, and Zn are generally lower than the safety limits given by the Chinese regulation safety and quality standards of agriculture products (GB2762-2012). As, Cd, and Pb contaminations are found in vegetables and fishes. The exceeding standard rates are 19 % for As, 3 % for Cd, and 25 % for Pb. Pb contaminations are found quite focused on the fish samples from traditional agri-product markets. The paper further analyzed the health risk of heavy metals in vegetables and fishes respectively from supermarkets and traditional agri-product markets; the results showed that the fishes of traditional agri-product markets have higher health risk, while the supermarkets have vegetables of higher heavy metal risk, and the supervision should be strengthened in the fish supply channels in traditional agri-product markets.     

Evaluation of heavy metal concentrations of edible wild-grown mushrooms from China

ABSTRACT

The heavy metal contents (Co, Cu, Fe, Mn, Ni, and Zn) of eight species of wild edible mushrooms from China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrophotometry after microwave digestion. The contents of Co, Cu, Fe, Mn, Ni, and Zn in caps of mushroom samples were 0.7–7.2, 16.2–70.4, 371–1315, 12.5–29.8, 7.1–58.5, and 77.8–187.4 mg kg^?1 dry matter (dm), respectively, while considerable differences were found to be 1.8–25.9, 9.8–36.3, 288–6762, 13.3–103.9, 5.9–78.7, and 38.7–118 mg kg^?1 dm for stipes. The results indicated that higher levels of Co, Fe, and Ni were found in the mushrooms samples analyzed. Zinc and manganese levels were similar to previous reports, whereas Cu was lower than literature values. Correlation analysis suggested that significant correlations were found between the minerals determined and the greatest amount of contamination is associated with Co, Mn, Ni, and Fe. The results of this study indicate that heavy metal contents in mushroom species are mainly related to the mineral resources of sampling sites.     

Adsorption properties of kaolinite-based nanocomposites for Fe and Mn pollutants from aqueous solutions and raw ground water: kinetics and equilibrium studies

Raw kaolinite was used in the synthesis of metakaolinite/carbon nanotubes (K/CNTs) and kaolinite/starch (K/starch) nanocomposites. Raw kaolinite and the synthetic composites were characterized using XRD, SEM, and TEM techniques. The synthetic composites were used as adsorbents for Fe and Mn ions from aqueous solutions and natural underground water. The adsorption by the both composites is highly pH dependent and achieves high efficiency within the neutral pH range. The experimental adsorption data for the uptake of Fe and Mn ions by K/CNTs were found to be well represented by the pseudo-second-order kinetic model rather than the intra-particle diffusion model or Elovich model. For the adsorption using K/starch, the uptake results of Fe ions was well fitted by the second-order model, whereas the uptake of Mn ions fitted well to the Elovich model rather than pseudo-second-order and intra-particle diffusion models The equilibrium studies revealed the excellent fitting of the removal of Fe and Mn ions by K/CNTs and Fe using K/starch with the Langmuir isotherm model rather than with Freundlich and Temkin models. But the adsorption of Mn ions by K/starch is well fitted with Freundlich rather than Temkin and Langmuir isotherm models. The thermodynamic studies reflected the endothermic nature and the exothermic nature for the adsorption by K/CNTs and K/starch nanocomposites, respectively. Natural ground water contaminated by 0.4 mg/L Fe and 0.5 mg/L Mn was treated at the optimum conditions of pH 6 and 120 min contact time. Under these conditions, 92.5 and 72.5% Fe removal efficiencies were achieved using 20 mg of K/CNTs and K/starch nanocomposites, respectively. Also, K/CNTs nanocomposite shows higher efficiency in the removal of Mn ions as compared to K/starch nanocomposite.     

Relevance of biotic parameters in the assessment of the spatial distribution of gastrointestinal metal and protein levels during spawning period of European chub (Squalius cephalus L.)

The present field study, conducted during the spawning period (April/May) of European chub (Squalius cephalus L.) from the Sava River in Croatia, indicates that seasonal changes of fish physiological state might cause variability in gastrointestinal metal (Cd, Cu, Fe, Mn and Zn), total cytosolic protein and metallothionein (MT) levels. During the period of fish spawning and increased metabolic activity, a significant relationship with chub hepatosomatic index was evident for Fe and Mn in gastrointestinal tissue (r?=?0.35 and 0.26, respectively) and in cytosolic fraction (r?=?0.32 and 0.41, respectively) and for Zn and Fe in the gut content (r?=?0.36 and 0.31, respectively). Total cytosolic protein and MT concentrations followed the same spatial distribution as Fe and Mn in all gastrointestinal fractions and as Zn in the sub-cellular fractions, with higher levels at upstream locations. Due to the role of essential metals in metabolic processes and gonad development, increased feeding and spawning activity in April/May resulted in higher gastrointestinal essential metal (Fe, Mn and Zn) and MT concentrations, which probably follow an increase in Zn concentrations, known as the primary MT inducer. Therefore, biotic factors should be considered as important confounding factors in metal exposure assessment, while their influence on gastrointestinal metal and protein levels should be interpreted depending on the season studied.     

Co-treatment of acid mine drainage with municipal wastewater: performance evaluation

Co-treatment of acid mine drainage (AMD) with municipal wastewater (MWW) using the activated sludge process is a novel treatment technology offering potential savings over alternative systems in materials, proprietary chemicals and energy inputs. The impacts of AMD on laboratory-scale activated sludge units (plug-flow and sequencing batch reactors) treating synthetic MWW were investigated. Synthetic AMD containing Al, Cu, Fe, Mn, Pb, Zn and SO₄ at a range of concentrations and pH values was formulated to simulate three possible co-treatment processes, i.e., (1) adding raw AMD to the activated sludge aeration tank, (2) pre-treating AMD prior to adding to the aeration tank by mixing with digested sludge and (3) pre-treating AMD by mixing with screened MWW. Continuous AMD loading to the activated sludge reactors during co-treatment did not cause a significant decrease in chemical oxygen demand (COD), 5-day biochemical oxygen demand, or total organic carbon removal; average COD removal rates ranged from 87–93 %. Enhanced phosphate removal was observed in reactors loaded with Fe- and Al-rich AMD, with final effluent TP concentrations <2 mg/L. Removal rates for dissolved Al, Cu, Fe and Pb were 52–84 %, 47–61 %, 74–86 % and 100 %, respectively, in both systems. Manganese and Zn removal were strongly linked to acidity; removal from net-acidic AMD was <10 % for both metals, whereas removal from circum-neutral AMD averaged 93–95 % for Mn and 58–90 % for Zn. Pre-mixing with screened MWW was the best process option in terms of AMD neutralization and metal removal. However, significant MWW alkalinity was consumed, suggesting an alkali supplement may be necessary.     

Copper amendments and soil ph affect distribution of different chemical forms of metals and their uptake by Swingle citrumelo seedlings

Abstract

This study was conducted to evaluate the effects of various rates of Copper (Cu) amendments (as CuSO₄.5H₂O at either 0, 25, 50, 100, 200, or 400 mg Cu kg^‐1) to soils with different pH values on the distribution of various chemical forms of Zinc (Zn), Iron (Fe), Manganese (Mn), and Aluminum (Al) in soils and their uptake by Swingle citrumelo citrus rootstock seedlings. The soils included Myakka fine sand (pH 5.70), Candler fine sand (pH 6.45), and Oldsmar fine sand (pH 8.16). The chemical forms of metals evaluated in this study included exchangeable, sorbed, organically bound, precipitated, and residual forms. An increase in Cu rates, lowered the pH in the Myakka and Candler fine sands, but not in the Oldsmar fine sand. This, in turn, resulted in an increase in the proportion of the readily soluble forms (the exchangeable + sorbed forms) of Zn and Mn, and decreased that of Fe in the Myakka and Candler fine sands. In those two soils, the organically bound forms of Zn, Fe, and Mn decreased with an increase in Cu rates. However, the proportion of readily soluble forms was not significantly influenced by increasing Cu rates in the Oldsmar fine sand. The total content of Zn, Fe, and Mn in citrus roots and that of Zn and Fe in the leaves, significantly decreased with an increase in Cu rates in the Myakka and Candler fine sands. In the Oldsmar fine sand, Cu rates through the entire range had no significant effects on the total contents of Zn, Fe, and Mn in the leaves or in the roots of Swingle citrumelo rootstock seedlings.     

Contamination of the River Ganga and its toxic implication in the blood parameters of the major carp Labeo rohita (Ham)

A field study was conducted to examine different physicochemical properties of water and various haematological and biochemical parametres of the fish Labeo rohita collected from the Ganga River (National river of India) at Varanasi district, India. The water was found to be greatly contaminated with a number of dissolved metals (Fe, Cr, Zn, Cu, Mn, Ni and Pb) whose concentrations were above the safe limits suggested by Bureau of Indian Standard (BIS 1991) for drinking water (Fe, 1,353.33 %; Cr, 456 %; Mn, 553.33 %; Ni, 4,490 % and Pb, 1,410 %). The metal accumulation in the fish blood was very high (Fe, 2,408 %; Cr, 956.57 %; Zn, 464.90 %; Cu, 310.57 %; Mn, 1,115.48 %) in comparison to the control fish maintained under strict quality control. Lower values of the various haematological parameters (total erythrocytes count, haemoglobin, haematocrit, mean corpuscular volume and O₂-carrying capacity) in the river fish in comparison to the control indicate toxic manifestation exerted by the contaminated river water on the fish. The higher level of total leucocytes count further illustrates stressed condition of the river fish. The toxic impact of the Ganga water is also expressed in the fish by the presence of higher levels of cholesterol, glucose, elevated activities of the enzymes aspartate amino transferase and alanine amino transferase, and lowered protein concentration.     

Trace elements in size-segregated urban aerosol in relation to the anthropogenic emission sources and the resuspension

Size segregated particulate samples of atmospheric aerosols in urban site of continental part of Balkans were collected during 6 months in 2008. Six stages impactor in the size ranges: Dp?≤?0.49 μm, 0.49?2?≈?30 %) followed by traffic (PC2, σ²?≈?20 %) that are together contributing around 50 % of elements in the investigated urban aerosol. The EF model shows that major origin of Cd, K, V, Ni, Cu, Pb, Zn, and As in the fine mode is from the anthropogenic sources while increase of their contents in the coarse particles indicates their deposition from the atmosphere and soil contamination. This approach is useful for the assessment of the local resuspension influence on element’s contents in the aerosol and also for the evaluation of the historical pollution of soil caused by deposition of metals from the atmosphere.     

Distribution of lead, copper and zinc in size-fractionated river bed sediment in two agricultural catchments of southern Ontario, Canada

Metal (Pb, Cu and Zn) partitioning in six separated sediment size fractions (<8, 8-12, 12-19, 19-31, 31-42, 42-60 microm) of river bed sediment have been analyzed by sequential extraction. The concentrations of some major elements (Si, Al, Ca, Mg, K, Na, Fe, Mn and P), and organic and inorganic C were determined to correlate the elemental composition of the sediment with metal speciation and grain size. Results show that Zn and Pb concentrations increase with decreasing grain size. For Big Creek and Big Otter Creek, respectively, the highest concentrations of Zn (326 and 230 mg kg(-1)) and Pb (158 and 67 mg kg(-1)) were found in the smallest (<8 microm) fraction, whereas the Cu levels (619 and 1281 mg kg(-1)) were most abundant in the second smallest (8-12 microm) fraction. The major accumulative phases for Cu, Zn and Pb were carbonates, Fe/Mn oxides and organic matter, but the relative importance of each phase varied for individual metals and grain sizes. The extraction data show increasing potential bioavailability of metals with decreasing grain size. Estimates of metal yields in the study catchments suggest that over 80% of the metal yield in sediment smaller than 63 microm is associated with solids smaller than 31 microm.     

Trace element contaminants in mineral fertilizers used in Iran

The application of mineral fertilizers which have contaminants of trace elements may impose concern regarding the entry and toxic accumulation of these elements in agro-ecosystems. In this study, 57 mineral fertilizers (nitrogen, potassium, phosphate, and compound fertilizers) distributed in Iran were analyzed for their contents of Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Fe. The results revealed that the contents of these trace elements varied considerably depending on the type of the element and the fertilizer. Among these elements, Fe displayed the highest average content, whereas Cd showed the lowest. Generally, the trace element contents in P-containing fertilizers were higher than those in nitrogen and potassium fertilizers. The mean values of trace elements (mg kg^?1) in P-containing fertilizers were 4.0 (Cd), 5.5 (Co), 35.7 (Cr), 24.4 (Cu), 272 (Mn), 14.3 (Ni), 6.0 (Pb), 226 (Zn), and 2532 (Fe). Comparing trace element contents to limit values set by the German Fertilizer Ordinance showed that the mean contents of potentially toxic trace elements, such as Cd and Pb, were lower than their limit values in all groups of fertilizers. On the other hand, while a number of fertilizers contained a high content of some essential trace elements, particularly Fe, they were not labeled as such.     

Deposition of Mn from Automotive Combustion of Methylcyclopentadienyl Manganese Tricarbonyl beside the Major Highways in the Greater Toronto Area,Canada

ABSTRACT

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Canada since 1976 as an antiknock agent in gasoline, completely replacing Pb in 1990. An early study of much higher Mn concentrations in gasoline showed that the combustion of MMT leads to the formation of inorganic manganese oxides, especially Mn₃O₄. Recent emission testing by Lawrence Livermore National Laboratory for Ethyl Corp. has shown that Mn is primarily emitted as a phosphate or sulfate along with minor amounts of oxides. The main objective of this research was to analyze the deposition of Mn from MMT to the terrestrial environment beside the major highways in the greater Toronto area (GTA), Canada. The results were compared with Pb and other trace elements such as Al, Ca, Fe, Mg, Cu, Zn, Na, and the Cl^- ion (water extractable) to study the behavior of Mn in soil. The study area was located near major Toronto highways 401 (urban) and 400 (rural), at 43° 67′ N and 79° 37′ W (latitude and longitude) (278,560 and 47,835 cars/day), respectively. Surface soil samples (0–5 cm depth) were collected at distances up to 40 m from the roadside. Parameters evaluated included total and available Mn and other trace elements, particle size, pH, organic content, and cation exchange capacity.     

Accumulation of Al, Mn, Fe, Cu, Zn, Cd and Pb by the bryophyte Scapania undulata in three upland waters of different pH.

Measurements were made of the contents of Al, Mn, Fe, Cu, Zn, Cd and Pb in Scapania undulata in three streams (D2, D5, D11) in the English Lake District. The stream waters had average pH values of 5.35 (D2), 5.81 (D5) and 7.26 (D11), the main differences in other major chemical components being in Mg, Al, Ca and alkalinity. There was generally more metal accumulation in the older parts of the plants, but this was not significant in all cases. Extents of accumulation varied with stream pH and dissolved metal concentration. For Al, accumulation was greatest in streams D2 and D5. Mn accumulated most in D5 and Fe was without preference. Cu, Zn and Cd accumulated mostly in the plants in stream D11 and Pb accumulated more in D5 and D11. In terms of enrichment factors (amount of metal in the plants divided by stream water concentration) the sequence was Zn < Cd < Cu < Mn < Pb < Al < Fe. Laboratory experiments supported the findings of the field data, providing evidence that uptake increases with pH at constant total metal concentration. The results are interpreted qualitatively in terms of the chemical speciation of the metals in the stream water and competition between metal ions and protons at the plant-water interface. It is suggested that Al, Cu, Zn, Cd and Pb behave according to chemical complexation, whereas redox processes and/or colloidal interactions may be significant for Mn and Fe.