Temperature-programmable furnace for ashing of foods in trace metal analysis

The use of programmable furnace in preparing samples for determining cadmium, lead, copper, and zinc by differential pulse anodic stripping voltammetry or atomic absorption spectrophotometry is convenient and time-saving. Recovery data for these 4 metals in various foods (tuna, sardines, and milk) were 93-96% for 0.01-1 ppm cadmium, 96-114% for 0.05-5 ppm lead, 100-108% for 2-10 ppm copper, and 97% for 10 ppm zinc.     

Die Wirkung der Schwermetalle Chrom,Nickel, Kupfer,Zink, Cadmium,Quecksilber und Blei auf die Aufnahme und Verlagerung von Kalium und Phosphat bei jungen Gerstenpflanzen

Effect of the heavy metals chromium, nickel, copper, zinc, cadmium, mercury and lead on uptake and translocation of K and P by young barley plants The uptake of potassium and phosphate into the roots and shoots of 7 days old barley plants from double-labelled (⁴²K, ³²P) nutrient solutions containing chromium, nickel, copper, zinc, cadmium, mercury or lead (10^?6 - 10^?4 moles/1) was measured in a constant environment after 5 hours, in order to compare early stages of toxicity. K and P uptake and translocation were inhibited by the 7 heavy metals to a different extent; K was more affected than P, and translocation of both nutrients into the shoots was more inhibited than uptake into the roots. Plants showed no visible injuries. Mercury had by far the greatest effect, zinc was almost ineffective: K uptake e.g. was reduced to 21% of the control by 10^?4 moles Hg/l, but only to 97% by the same amount of Zn, and P translocation was reduced to 8% by Hg, but was not affected by Zn. The least significant effect of Hg was detectable at a concentration of 4.10^?7 moles Hg/l ( = 0,08 ppm) in the nutrient solution, the effect of Zn only above 10^?4 moles Zn/l ( = 6,5 ppm). Arranging the tested heavy metals according to their effects leads to the sequence Hg > Pb > Cu > Cd > Cr > Ni > Zn which corresponds – apart from two deviations – to the electrochemical series of the elements.     

The effect of sewage‐sludge on the heavy metal content of soils and plant tissue

Abstract

Domestic sewage sludge applied to farm fields at a rate of 44.9 kg/ha in a mixture with lime and sawdust was found to increase the soil levels of cadmium, chromium, copper, lead, mercury, nickel and zinc. The average levels in sludge treated soil were: 0.11, 0.56, 3.59, 2.72, 0.068, 1.49 and 2.57 ppm, respectively. The increases were small and the overall loading factors were well below recommended maximums. The uptake of these heavy metals by grass and legume plants was variable with cadmium, copper and zinc levels being higher in those plants growing in the sludge treated soils but only copper was significantly higher. The heavy metal contents found were all within the levels normally found in grass and legume plants. The higher mean concentration in plants growing on the sludge treated soils were cadmium 0.495; chromium 1.22; copper 12.3; lead 1.54; mercury 0.022; nickel 4.08 and zinc 28.4 ppm.     

Atmospheric background levels and transport of heavy metals in the Balearic islands

Calcium and seven minor inorganic components (iron, manganese, nickel, chromium, copper, cadmium and lead) were determined in aerosols collected at the Alfabia and Sóller stations (Majorca, Spain), 1100 and 100 m above sea level, respectively. The results obtained reveal a marked influence of long-distance transport of natural and anthropogenic materials. A statistical study allowed the metals to be grouped according to their origin.     

Removal of Heavy Metals in Storm Water Runoff Using Porous Vermiculite Expanded by Microwave Preparation

The main objective of this study was to examine the effectiveness of vermiculite for removing heavy metals from water. Vermiculite components were analyzed by X-ray fluorescence, and the concentrations of metal ions were measured by inductively coupled plasma spectrometry. Serial batch kinetic tests and batch sorption tests were conducted to determine the removal characteristics for heavy metals in aqueous solutions. Solution pH values of tests with the inflated vermiculites generally increased and then stabilized. Equilibrium pH was generally established within 5?h. Removal rates of inflated vermiculite were tested at the initial concentration of 3?mg/L. At equilibrium concentrations, except for chromium (36.23%), most heavy metals were effectively removed (96.08?C98.54%). Finally, sorption data were correlated with both Langmuir and Freundlich isotherms. For each metal, the Q _max obtained using the Langmuir isotherm was as follows: lead, 725.4?mg?kg^?1; cadmium, 568.8?mg?kg^?1; zinc, 540.2?mg?kg^?1; copper, 457.2?mg?kg^?1; and chromium, 0.9?mg?kg^?1. The study results indicate that inflated vermiculite has outstanding removal rates and therefore can be used as an adsorbent for various heavy metals.     

Adsorption of Toxic Metals on Modified Polyacrylonitrile Nanofibres: A Review

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.     

Schwermetalle in Oberböden des Warthetals unter städtischem Einfluß

Heavy metals in surface soils of the Warta river valley in an urban area In the urban area of the city of Poznan the contamination with heavy metals was investigated. From the top soil layers of five cross-sections of the valley of the Warta river 87 samples were collected. Beside common soil characteristics the contents of arsenic, barium, cadmium, chromium, copper, iron, lead, manganese, phosphorus and zinc were analyzed. Predominantly the level of contamination with heavy metals is low in the valley soils. A higher level was found in the area of the old city centre. Especially the contents of lead, copper and zinc were raised. Downstream of the sewage plant discharge into the river Warta increased contents of lead and cadmium were found. The distribution of heavy metals in the river Warta sediments indicates that the reason of the local increase of heavy metal contents is the sewage water discharge, Correlations between the content of different heavy metals and other soil properties (pH, clay and P-content, C/N-ratio) were calculated.     

Gas chromatographic determination of formaldehyde in coffee via thiazolidine derivative

Thiazolidine formed from trace quantities of formaldehyde in an aqueous solution containing cysteamine at pH 8 was extracted with chloroform and subsequently analyzed by a gas chromatograph equipped with a fused silica capillary column and a thermionic nitrogen-phosphorus specific detector. Recoveries of formaldehyde from the aqueous solutions at levels lower than 1 ppm were slightly over 100%. Quantitative analysis of formaldehyde in commercial brewed and instant coffees showed 3.4-4.5 ppm in the brewed and 10-16.3 ppm in the instant coffee.     

Mercury content of soils in Western Britain with special reference to contamination from base metal mining

Mercury was determined in 51 soil samples from historic base metal mining areas of England and Wales, together with cadmium, copper, lead, zinc, pH and organic content. Background mercury was calculated as 0.093 ppm whence 51% of the samples were judged to be contaminated. A very strong statistical correlation between mercury and lead and weaker but significant correlations between mercury and copper and zinc were found. Highest levels of mercury (maximum, 1.78 ppm Hg) and other metals occurred in soils derived from the floodplain of a river which was at one time badly polluted by mine waste. In a profile pit near a lead mine in the west of England both mercury and lead were enriched in surface horizons. It is concluded that land contaminated by heavy metals, especially lead, in the historic metal mining areas of England and Wales is also likely to be contaminated by mercury.     

Screening method for determination of high levels of cadmium, lead, and copper in foods by polarized Zeeman atomic absorption spectrometry using discrete nebulization technique

A screening method for determination of cadmium, lead, and copper in foods was developed. The sample (1-3 g) is digested with HNO3-H2SO4-HClO4 in a centrifuge tube attached to a straight glass tube that prevents loss of HNO3 by volatilization. After digestion, potassium iodide, H2SO4, and MIBK (4-methyl 2-pentanone) are added, and the metals are extracted with MIBK as metal iodides. The MIBK solution is injected and the metals are determined by flame polarized Zeeman atomic absorption spectrometry using a discrete nebulization technique. Recoveries of metals from fortified milk powder, unpolished rice, fish, beef, peanut butter, apple, and cabbage were satisfactory. The analytical results for NBS Oyster Tissue and NIES Pepperbush, Chlorella, and Mussel agreed with certified or reference values except lead in Pepperbush. The limits of quantitation for cadmium, lead, and copper were 0.01, 0.09, and 0.02 ppm, respectively. This method is simple and safe for routine analysis of high levels of cadmium, lead, and copper in foods.     

Heavy Metal Pollution and Eutrophication in the Lower Salado River Basin (Argentina)

Levels of heavy metals (chromium, copper, lead and cadmium) in water and sediments of the lower Salado River (Argentina) are presented and compared to Canadian and Argentinian environmental standards. Measurement of metal levels was performed using atomic absorption spectroscopy. In order to interpret analytical results, one way ANOVA, hierarchical cluster analysis and correlations were used. Geoaccumulation Index was used as a measure of metal pollution in sediments. There were differences between the accumulation of metals in sediments and water and the control sampling site. Heavy metals, especially chromium, copper and lead, appear to be an important problem to these freshwater environments.     

Metals in Main Rivers of Azerbaijan: Influence of Transboundary Pollution

Silver, arsenic, cadmium, chromium, cobalt, copper, mercury, lead, and zinc were determined monthly during 2004–2008 at 11 sites in the Kura–Araks river system, Azerbaijan. Suspended fractions of the elements were studied at the five sites experiencing the highest load. Metal concentrations varied moderately at each site but differed substantially between sites. Sites near the borders with Armenia and Georgia were most polluted, both with respect to soluble concentrations and percentage transported in suspended form. Lower parts of the Kura river were shielded from metal contamination by an upstream reservoir acting as a metal trap. Corresponding removal was not evident in Araks, its main tributary, where particularly high concentrations of arsenic were observed. At the most contaminated sites, more than 60% of cadmium, cobalt, chromium, copper, manganese, nickel, lead, and zinc was transported in suspended form whereas arsenic and molybdenum occurred mainly in soluble form. Dynamics of metals in the Kura–Araks water/sediment system should be further studied to meet future problems.     

Evaluation of Green Waste and Popular Twigs Biochar Produced at Low and High Pyrolytic Temperature for Efficient Removal of Metals from Water

Biomass-derived biochar is considered as a promising heavy metal adsorbent, due to its favorable physicochemical properties, from aqueous solution as compared with other adsorbents. However, there is a limited number of studies on the effects of biochar produced from different feedstocks and pyrolytic temperatures on metal removal from metal-contaminated water. So in this study, the removal of the most prevalent heavy metals [(lead (Pb(II)), cadmium (Cd), and chromium (Cr)] by green waste biochar (GWB) and popular twigs biochar (PTB), produced at different pyrolytic temperatures, i.e., low 350 and high 650 °C, has been investigated, following the determination of physical and chemical properties of biochar. The efficiency of heavy metals removal of biochar was studied at different concentrations of heavy metals (10 and 100 μg mL^?1), biochar types and treatment duration (3, 6, 9, and 12 h) at isothermic condition of aqueous solution. Results revealed that both feedstock type and pyrolytic temperature to produce biochar significantly affected its metal sorption capacity. The maximum sorption capacities of all three metals, i.e., Pb (II), Cd, and Cr were determined in the GWB produced at low pyrolytic temperature 350 °C after 9 h of treatment duration at both high and low metal concentrations. This highest sorption capacity of all metals by low pyrolytic temperature produced GWB was due to its better physicochemical properties especially high surface area, cation exchange capacity, and oxygen-containing functional groups as compared with woody feedstock based high pyrolytic temperature produced PTB. Conclusively, low pyrolytic temperature produced GWB was evaluated as a potential adsorbent to efficiently reduced heavy metal concentration in metal-contaminated water.     

Comparison of Heavy Metal Adsorptions by Thai Kaolin and Ballclay

The adsorption characteristics of heavy metals: cadmium(II), chromium(III), copper(II), nickel(II), lead(II), and zinc(II) ions by kaolin (kaolinite) and ballclay (illite) from Thailand were studied. This research was focussed on the pH, adsorption isotherms of single-metal solutions at 30–60 °C by batch experiments, and on ion selectivityin mixed and binary combination solutions. It was found that, except Ni, metal adsorption increased with increased pH of the solutions and their adsorption followed both Langmuir and Freundlich isotherms. Adsorption of metals in the mixture solutions by kaolin was: Cr > Zn > Cu ≈ Cd ≈ Ni > Pb, and for ballclay was: Cr > Zn > Cu > Cd ≈ Pb > Ni. The adsorption of metals was endothermic, with the exception of Cd, Pb and Zn for kaolin, Cu and Zn for ballclay. Kaolin and ballclay exhibited relatively hard Lewis base adsorption site. The presence of other metals may reduce or promote the adsorption of heavy metals. The presence of Cr³⁺ induced the greatest reduction of metal adsorptiononto kaolin, as did the presence of Cu²⁺ for ballclay.     

Assessment of heavy metal uptake and translocation in Dyera costulata for phytoremediation of cadmium contaminated soil

Abstract

Heavy metal pollution is a widespread global problem causing serious environmental concern. Cadmium, one of the heavy metals, is water soluble and can be transferred from soil to plants and enter into the food chain. It is detrimental to human health because it accumulates in the body and can cause renal tubular dysfunction, pulmonary emphysema and osteoporosis. This heavy metal needs to be cleaned up for a clean and safe environment. An experiment was conducted to evaluate the potential of Dyera costulata as a phytoremediator to absorb cadmium from contaminated soils. Dyera costulata seedlings were planted on six different growth media (soil + different levels of cadmium): Control, 25 ppm Cd, 50 ppm Cd, 75 ppm Cd, 100 ppm Cd and 150 ppm Cd. The highest growth performance mainly height, basal diameter and number of leaves were in the control, 50 ppm Cd and 25 ppm Cd treatments, respectively. The highest accumulation of cadmium (52.9 ppm) was in the 75 ppm Cd treatment. Among the plant parts, leaves showed the highest concentration of cadmium. Dyera costulata showed high translocation factor and low bioconcentration factor values in soil at high cadmium concentrations and was also able to tolerate and accumulate high concentrations of cadmium. The roots of Dyera costulata were found to be suitable for the absorption of cadmium in contaminated soils. This species can be an efficient phytoremediator for soils contaminated with cadmium.     

Levels of 3,3',4,4'-tetrachloroazobenzene in diuron and linuron herbicide formulations

Levels of 3,3',4,4'-tetrachloroazobenzene (TCAB) were determined by capillary gas chromatography (GC) with electron-capture detection (ECD) in 25 samples of diuron and linuron formulations obtained from the Canadian market. Acidic aqueous methanol was used to retain urea herbicide and the neutral TCAB was allowed to partition into hexane. Silica gel was used for cleanup of the hexane extract, followed by GC/ECD determination. Recovery data obtained at 4 different spiking levels (i.e., 0.3, 0.1, 1.0, and 5.0 ppm) in linuron averaged 93, 86, 85, and 97%, respectively. For diuron, spiking was done at 0.5, 1.0, and 5.0 ppm levels and the corresponding average percent recoveries were 95, 101, and 104. The TCAB contamination level observed in diuron on a 100% active ingredient basis ranged from 0.15 to 3.38 ppm, whereas in linuron, it varied from 0.91 to 10.28 ppm.     

应用相平衡分配法建立滇池沉积物金属环境质量基准

For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equilibrium-partitioning- based numerical SQGs have been developed or are currently available because of the confounding factors mediating the bioavailability of metals. A study was conducted at Dianchi Lake, which is a heavily eutrophicated lake on the Yunnan- Guizhou Plateau, China with the focus on the measurement of partitioning coefficient （Kp） and SQGs derivation and normalization to acid volatile sulfide （AVS）, fine material, and organic carbon. Using new normalization methods, SQGs were formulated for seven metals including copper, zinc, lead, cadmium, chromium, mercury, and arsenic in Dianchi Lake. In Dianchi Lake sediments, the fine material contributed 25.4%-36.0% to the SQG values, with the largest contribution to the SQG value of mercury; AVS contributed 2.9%-75.0% to the SQG values, with the largest contribution to the SQG value of cadmium. This indicated that the fine material and the AVS were the most important controlling factors to the bioavailability of mercury and caximium, respectively. The contribution of total organic carbon （TOC） to the SQG values of copper and leaxi was 3.8% and 7.1%, respectively, indicating that at relatively lower concentrations, the contribution of TOC was not significant. In addition to normalization methods, appropriate procedures for the application of EqPA including sample collection, storage, and analysis are also essential to improve the reliability of SQGs. The normalized Dianchi Lake SQGs were higher than most of the empirically based SQGs developed in North America, but lower than Hong Kong interim SQGs except for cadmium and arsenic. The differences could be attributed to the approaches used for derivation of SQGs and the water quality criteria adopted and the differences in the physical and chemical characteristics of the sediments.     

Gas chromatographic determination of maleic hydrazide residues in potato tubers

A gas chromatographic (GC) method is described for the determination of maleic hydrazide residues in potato tubers by oxidation of maleic hydrazide with aqueous lead dioxide to 3,6-pyridazinedione in the presence of cyclopentadiene. The reaction product, a volatile Diels-Alder adduct, could be detected in potatoes at levels in excess of 0.05 ppm with an electron capture detector. Recoveries of maleic hydrazide (as the Diels-Alder adduct) from potatoes at fortification levels of 0.1 to 10 ppm averaged 91.7%.     

Sorption Removal of Anions and Cations in Single Batch Systems by Uncalcined and Calcined Mg-Al-CO3 Hydrotalcite

In this study, the sorption removal of two anions (phosphates, thiocyanates) and three cations (cadmium, lead, nickel), in single batch systems, was investigated from aqueous solutions. The process involves the sorption of the ions by hydrotalcite, which is a double-layered mixed-metal hydroxide and belongs to the family of anionic clays. The sorbent used was Mg-Al-CO₃ hydrotalcite in two forms: uncalcined and calcined at 500 °C. The calcined material showed the higher sorption capacity, for all the ions, than the uncalcined. The approximate sorption capacity of calcined material was: phosphates 250 mg g^-1, thiocyanates 80 mg g^-1, nickel/lead 100 mg g^-1 and cadmium 70 mg g^-1. The kinetic results of the anions were fitted satisfactory with the Lagergren equation. Since the sorption capacity is relatively high, hydrotalcite can be considered as a potential material for sorption of both anions and cations in wastewater treatment systems.     

Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide.

The use of chlorine dioxide (ClO(2)) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO(2)(-)) and chlorate (ClO(3)(-)) as well as possible mutagenic/carcinogenic reaction products. Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO(2) solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay. No mutagenic activity was detected in the treated fish samples or test solutions with ClO(2). Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S. typhimurium TA 100. No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO(2) at 3.9-34.9 ppm. However, low levels of chlorate residues were detected in some of the treated samples. In most cases, the increase in chlorate in treated seafood was time- and dose-related.