Aqua Regia Extraction Research Articles

Copper and other heavy metals in specialized crops and their effects on soil coenosis

The background of the project are claims of the EU regulation to generate reliable data considering the extent of copper contamination in soils of specialized crops in order to decide about copper restrictions in organic farming.2522 single soil samples were collected on 85 vineyard and 13 hop areas with different management histories. Samples were taken from sites presently under cultivation, formerly cultivated, and sites without anthropogenic copper contamination as control, indicating natural background values. In addition to Aqua Regia extraction for determining total copper contents, available plant copper content was analyzed in NH~4~NO~3~ extraction. Soil parameters such as pH-value, C/N ratio, soil type etc. were also analyzed. The correlation between plant-available and total copper contents is not very high, probably due to the broad range of relevant values e.g. soil parameters or cultivation measurements. An ongoing biological survey about the present status of earthworm populations will give information about possible impairments of soil coenosis.

Investigation of the Effect of Mesh Size on the Effectiveness of Hotplate Aqua Regia Extractions

Aqua regia extractions with subsequent inductively coupled plasma determinations are a very common method of elemental analysis of soils and sediments. Before extraction, the material must be dried and sieved. Small variations in this early step can have a significant impact on the later outcomes, especially for unassisted (for example, without ultrasonic or microwave) extraction procedures. Therefore the impact of mesh size on the sieving process was investigated. A mesh size of 2.0 mm or greater yielded unacceptably high variations between the subsamples and a very poor recovery rate when compared to a 0.063-mm sieve. A mesh size of 0.3 mm resulted in the best outcomes, losing nearly no material in the fine sediment samples and about a tenth in the coarse samples. The precision was high for the 0.3-mm samples as well, only negligibly surpassed by the 0.1-mm samples for some materials.

Physical Composition, Nutrients and Contaminants of Typical Waste Dumping Sites

Problem statement: The composition of wastes is quite variable depending upon the generating source and mode of collection. Most of the material from the domestic activities will be organic in nature and contains essential plant nutrients, whereas the dumping material of commercial and industrial wastes usually contains appreciable amounts of heavy and potentially toxic metals and organic pollutants. Approach: Objective of the present study was to characterize the physico-chemical properties of the waste material and the distribution and extent of toxic pollutants in three selected typical dumping sites in the state of Haryana, India. Results: 62-65% of the waste fine material consisted of mineral particles and biodegradable organic waste, 20-25% consisted of construction and demolition waste and the remaining 10-15% were other materials such as study, plastic, metals, glass and timber, with an amount of polyethene of 3.4-5.7%. The ratio of the plant available concentrations of P, K and S and their total amounts were 3-7% for P and 1-4% for S, whereas the macronutrient potassium reached values of 29-39%. Metals As, Ba, Cd, Cr, Cu, Ni, Pb and Zn were present in all samples (total concentration in aqua regia extract). As, Ba, Ni and Pb did not show clear differences between the three investigates sites. Cd, Cr and Zn concentrations were high but different at the different sites (Cu maximum: 1,964 mg kg−1, Zn maximum: 2,200 mg kg−1). The mobility of the metals was calculated as the ratio of DTPA/aqua regia extraction. Cd showed the highest ratio (18-22%), while the other calculated metals showed much lower ratios (Cu 6.7, Pb 7.9 Ni 2.1, Zn 3.6 and Cr 0.5%). In general, PAH and benzo(a)pyrene concentrations fell below the detection limit. Also the phenol index did not exceed the detection limit of 1.2 mg kg−1 (with two exceptions). In 14 out of 36 samples a GC-MS screening was conducted in order to get an overview of the organic pollutants usually present in the dumpsites. In all cases there was no relevant amount of organic pollutants that would be capable of measurement. Conclusion: The dumping sites are plant nutrient deposits, particularly for K, which could be used in future in a line with ideas of urban mining. The use of the waste material for fertilizing purposes may be restricted due to the metal contaminant concentrations. The analyzed organic pollutants did not indicate problematical concentrations.

Determination of Mercury by Anodic Stripping Voltammetry in Aqua Regia Extracts

This work presents the optimization process of mercury determination by Anodic Stripping Voltammetry (ASV), using a glassy carbon modified with a gold film as working electrode, in samples extracted by aqua regia. The samples may contain Cu, Fe or Pb in high concentrations. In these conditions the usual Hg determination by ASV is almost impossible. The effects of the supporting electrolyte on the sensitivity of the method and chloride and nitrate ions concentration were studied. Supporting electrolyte was selected between: HCl, HNO 3, HClO 4 and CH 3COOH. Our results show that the best sensibility is obtained with HClO 4 0.10 M. High chloride concentration decreases the useful potential window and the peak current. However, small chloride additions are required to obtain high peak currents because chloride prevents Au film poisoning. Another interference studied was that of Cu and Fe. This kind of interference can be avoided if the sample in the electrochemical cell is exchanged for fresh electrolytic solution (HCl 0.01 M -HClO 4 0.10 M) before the stripping step.

INFLUENCE OF POLLUTION LEVEL ON HEAVY METALS MOBILITY IN SOIL FROM NW ROMANIA

To assess the influence of pollution degree on the heavy metals (Cu, Cd, Zn, Pb) mobility in soil, total metals content obtained by extraction in aqua regia and extractable contents in a buffered diethylenetriaminepentaacetic acid (DTPA) solution were measured using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Soil samples were collected from two areas from NW Romania with different pollution levels: a mining area (Baia Mare) and a rural area (Iclod). High pollution level with heavy metals was found in Baia Mare area, whereas contents of metals in Iclod did not exceed the alert limits established by Romanian legislation. The percentages of extractable metals were calculated, and correlations between soils pollution levels and heavy metals mobility were made. The results showed that despite the significant difference between the total metal content in soil from the two regions, estimated as the aqua regia extractable content, the percentages of DTPA extractable metals were comparable for Pb and Zn, while those for Cu and Cd were higher in the polluted region. However, significant correlation coefficients were found between total and mobilisable metals content in unpolluted site compared to the polluted site.

Soil monitoring of arsenic by methanol addition DRC ICP-MS after boiling aqua regia extraction

Trace levels of arsenic (As) in soil samples can be determined by conventional ICP-QMS with closed vessel digestion, but always suffer from interference of ions originating from the complicated matrix, mainly including 40Ca35Cl+, 40Ar35Cl+, 39K36Ar+, 150Nd2+, 150Eu2+ and 150Sm2+etc. In this study, 75As+, the mass for general detection, was effectively changed to 75As16O+ which could be detected at m/z 91 by reaction with oxygen in a Dynamic Reaction Cell (DRC). For the new interference of 91Zr+ on 75As16O+, boiling aqua regia extraction was used to remove most of the zirconium in the sample preparation procedure, and the residual 91Zr+ was oxidized to 91Zr16O+ by oxygen in the DRC. In addition, the signal intensity of 75As16O was improved 4-fold by addition of 4% methanol into the sample solution. The signal to background ratio (SBR) of As was obviously improved from 0.18 to 205 (the certified arsenic concentration is 1 μg L−1), and a limit of quantification (LOQ, 10σ) of 0.1 ng g−1 was obtained. The proposed method was successfully applied to analyze 20 soil samples collected from pig farms in livestock farming processes, and shows its great potential for trace As determination in environmental and geological samples.

Aqua regia extracted metals in sediments from the industrial area and surroundings of Pančevo, Serbia

Surface and buried sediments were analyzed for Ba, Ca, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and V, as well as for total carbon and hydrogen to assess the distribution of sediment pollution due to the vicinity of the petrochemical complex. The samples, collected from 20 locations within the petrochemical complex and from 16 locations outside the complex, were aqua regia extracted and analyzed by ICP/OES. Metals were determined with an acceptable accuracy for certified metals of 82–113%. The precision for the aqua regia extraction was satisfactory, less than 20%, except for Cd where it was 28%. Comparison of the data from the petrochemical with those from the non-petrochemical areas showed different distributions of the metals. Metals that exceeded the baseline range; Ba, Cd, Cu, Zn and Pb, were detected in higher concentrations in sediments that were under the influence of the chlor-alkali plant within the petrochemical complex. Comparison with data from the petrochemical complex and its surroundings and their distribution demonstrated that the metal compositions of the sediments were modified by anthropogenic activities.

Relative extraction ratio (RER) for arsenic and heavy metals in soils and tailings from various metal mines, Korea

This study focused on the evaluation of leaching behaviours for arsenic and heavy metals (Cd, Cu, Ni, Pb and Zn) in soils and tailings contaminated by mining activities. Ten representative mine soils were taken at four representative metal mines in Korea. To evaluate the leaching characteristics of the samples, eight extraction methods were adapted namely 0.1M HCl, 0.5M HCl, 1.0M HCl, 3.0M HCl, Korean Standard Leaching Procedure for waste materials (KSLP), Synthetic Precipitation Leaching Procedure (SPLP), Toxicity Characteristic Leaching Procedure (TCLP) and aqua regia extraction (AR) methods. In order to compare element concentrations as extraction methods, relative extraction ratios (RERs, %), defined as element concentration extracted by the individual leaching method divided by that extracted by aqua regia based on USEPA method 3050B, were calculated. Although the RER values can vary upon sample types and elements, they increase with increasing ionic strength of each extracting solution. Thus, the RER for arsenic and heavy metals in the samples increased in the order of KSLP<SPLP<TCLP<0.1M HCl<0.5M HCl<1.0M HCl<3.0M HCl. In the same extraction method, the RER values for Cd and Zn were relatively higher than those for As, Cu, Ni and Pb. This may be due to differences in geochemical behaviour of each element, namely high solubility of Cd and Zn and low solubility of As, Cu, Ni and Pb in surface environment. Thus, the extraction results can give important information on the degree and extent of arsenic and heavy metal dispersion in the surface environment.

Chemical characterization of PM10 fractions of urban aerosol

The goal of this investigation was to give an overview about the trace metal and total organic/inorganic carbon (TOC/TIC), water-soluble carbon (WSOC) and polyaromatic hydrocarbons (PAH) concentrations in the PM10 aerosol fraction in Budapest and to monitor monthly changes during the sampling period, whether there is a tendency in the seasonal change of the concentrations. The sampling took place in Budapest, Hungary between September 2004 and August 2007 in an area with high traffic density. For the sampling, a high-volume aerosol sampler equipped with a PM10 head was used. The samples were taken onto quartz fiber filters. Each month, one sample was collected. Sampling time was 96h, the air intake was 30m3/h, resulting in 2880m3 sampled air volume.To measure the metal concentrations two types of sample preparation were used: microwave assisted aqua regia extraction and water extraction by sonication. In both cases, the solutions were analyzed by using a sector field inductively coupled plasma mass spectrometer (SF–ICP–MS). The following 23 elements were investigated: V, Cd, Zn, Cu, Ni, Sb, Sn, Cr, Pt, Pb, Te, Tl, U, Mn, Fe, Co, Ga, Rb, Sr, Mo, Ag, Bi, Li. Comparing the data obtained from the aqua regia extraction to some other cities, the measured trace elements were found in moderate concentration. In the water extract, a significant part of zinc and thallium was found. During the sampling period, no proof of seasonal change in trace element concentrations was found. Trace metal and total organic/inorganic carbon concentrations in Budapest were similar to the concentration data measured in other cities with exception of Mn, Ga, Rb, Cd which are present in higher concentration in Budapest. The TOC content in the PM10 fraction amounted to 30–50%, and its value was the highest during the winter period due to the heating.The yearly average concentration of polyaromatic hydrocarbons was almost constant over the investigated period, but its seasonal change is more than one order of magnitude.

Assessment of metals contamination of soils in Ulaanbaatar, Mongolia

The purpose of this survey is to investigate the current status of metal pollution of the soil in Ulaanbaatar, the capital city of Mongolia. During the last decade, the city has been rapidly urbanized. Twenty-two soil samples were collected from different parts of the city and analyzed by aqua regia extraction. Generally, metal pollution was not a serious problem in the city and there was no significant evidence of infiltration of metal solutions into subsoil (at a depth of 30cm). However, it was recently found that the arsenic(As) concentration in the soil was higher than the guideline value and the lead(Pb) content in some samples was higher than normal. The source of As pollution appears to be the coal combustion in three power plants in the city. The sources of the increase in Pb pollution might be the remarkable increase in the number of used vehicles and the increase in the use of leaded fuel in the last few years. To evaluate the leaching potential of heavy metals, sequential extraction was conducted. The quantity of the easily extractable fraction of metals was lower than that of the hardly extractable (residual) fraction. As a result, the leaching potential of heavy metals in Ulaanbaatar was found to be quite low.

Geochemical processes controlling the spatial distribution of selenium in soil and water, west central South Dakota, USA

Selenium (Se) is essential in the human diet, but has a low threshold for toxic concentration. It is recommended that nutrients such as Se should be consumed through foods as part of a normal diet. Se concentrations in crops and meat depend on the amount of labile Se in the soil where crops and forage are grown. Therefore, managing agriculture for optimal Se in grain crops and forage requires an understanding of the distribution and mobility of Se. Elevated concentrations of Se occur in waters, soils, and forage 120 km west of Pierre in west central South Dakota, USA. The research site lies in an elevated, dissected plain where soils developed on gently dipping Pierre Shale. Soils were sampled along catena transects and waters collected from soil, ponds, and shallow borings in areas of known elevated forage and crop Se. Soil extracts from saturated-paste extraction and acid (aqua regia and hydrofluoric acid) extraction were analyzed. Selenate was the dominant Se species in both acid and saturated-paste extracts; selenite and organic Se were below detection (<0.2 ppb) in the same soil extracts. On average, 98% of soil Se was not water-soluble. The distribution of total Se shows much less spatial variation than water-soluble Se in the areas sampled. Se shows correlation with organic carbon in soils and waters, suggesting its association with organic carbon. Ca shows some correlation to Se in acid extracts, but not in saturated-paste extracts or in waters. Total Se shows no significant correlation to Na, Mg, and total S in the soils. Se in saturated-paste extracts and water samples shows good correlations with Na, Mg, and SO4, suggesting that evaporitic Na–Mg–sulfate minerals may temporarily concentrate water-soluble Se in shallow soils. The dissolution and precipitation of these Na–Mg–sulfate salts together with pH and oxidation–reduction conditions apparently control water-soluble Se distribution and mobilization in shallow subsurface environments.

Selenium and other trace element in phosphorites: A comparison between those of the Bayovar-Sechura and other provenances

Data of trace element composition of phosphorites are scarce and incomplete. Phosphorites of different origins can vary substantially in trace element contents. In this paper 20 trace element concentrations of 35 sample phosphorites are reported. The geographical provenance is: Bayovar-Sechura (Peru), Khouribga, Youssoufia and Boucraa (Morocco), Gafsa (Tunisia), Florida (USA), Idaho and Phosphoria Formation (USA), North Carolina (USA), Algeria, Israel, Senegal, Syria and Togo. Aqua regia extracts were used to estimate the “pseudototal” values, following standard procedures (ISO 11466, 2002) and measured by ICP-AES and ICP-MS. The ratio of medians of trace elements from Sechura versus other provenances, decreases in the following sequence: Co(9) > Mo (3.5) > Mn (2.75) > As (1.65) > Sn (1.21) > Sr (1.16) > Cr, Cu, Ni, Pb (1.02) > Tl (0.86) > Se (0.67) > U (0.53) > Cd, Th (0.5) > V (0.44) > Sb (0.38) > Zn (0.29) > Ag (0.25) > B (0.24). Using multivariate methods we have seen that there are three main clusters: a first group with Phosphoria Formation, Idaho, Youssoufia and Senegal samples; a second group with Sechura phosphorites, enriched in Co and Mo and the third consisting of the remaining samples. The highest trace element enrichment factors in decreasing order are: Cd, 386 (Idaho, USA) > Ag, 78.5 (Idaho, USA) > Se, 73.3 (Youssoufia, Morocco) > U, 46.5 (Israel) > Mo, 43 (Sechura II, Peru) > Cr, 41 (Tobene, Senegal) > B, 11.6 (Khouribga KIIC, Morocco) > Sr, 10.4 (Israel) > Zn, 10.2 (Idaho, USA). Mo enrichment is peculiar to Phosphorites of Sechura. The Permian phosphorites from Idaho and Phosphoria Formation, accumulate Cd, Ag, Se, Zn Sb, V, As, Tl and Cu. The depleted trace element assemblages of Sechura phosphorites are different from the other provenance phosphorites. Selenium and B normality is the main difference between Sechura phosphorites versus the other provenance. The whole of the normal, enriched and depleted trace element in phosphorites, both individually and in assemblages, can be a useful tool such as a discriminating fingerprint in the research of the origin of the phosphorites.

Tailings Mineralogy and Geochemistry at the Abandoned Haveri Au–Cu Mine, SW Finland

Fourteen samples from the Haveri Au–Cu mine tailings were studied by reflected-light microcopy, scanning electron microscopy, X-ray powder-diffraction, and sequential extraction methods, and 12 water samples were analyzed for total and dissolved elements to delineate the extent of sulfide oxidation and its impact on nearby surface waters. Water-soluble, adsorbed-exchangeable-carbonate (AEC), Fe (oxy)hydroxides, Fe oxide, and Fe sulfide fractions were extracted sequentially. The oxidation layer was found to vary from 50 to 140 cm: the upper part was nearly depleted in primary sulfides, especially pyrrhotite [Fe(1−x)S] and pyrite (FeS2); in the lower part, discontinuous cemented layers were detected. Secondary Fe (oxy)hydroxides and Fe oxyhydroxysulfates were abundant in the oxidation layer and were slightly enriched in trace elements, including As (up to 80 mg/kg), Cu (300 mg/kg), and Zn (150 mg/kg). Almost half of the As (average 25 mg/kg) were present as secondary minerals susceptible to redissolution. The pH of the vadose tailings varied from 2.46 to neutral, and the total sulfur content varied from 1 to 6.5% (average 2.9%). Aqua regia extraction showed that the Haveri tailings are characterized by low concentrations of the elements Cd, Cr, Pd, and slightly elevated concentrations of As, which are present at very low concentrations in the surface water (<6 μg/L). However, runoff that flows on top of the tailings and discharges into the nearby lake carries Co, Cu, Ni, and Zn (concentrations of each range from 500 to 1,800 μg/L). Additionally, dissolution of sulfides and Fe precipitates may mobilize trace metals in the ground water. Thus, overall, there is a small continuous release of AMD into Lake Kirkkojarvi, but the environmental impacts to the lake are presently small.

Application of portable X-ray fluorescence (pXRF) for heavy metal analysis of soils in crop fields near abandoned mine sites

To get representative soil samples, a sampling method was verified for crop fields in the vicinity of abandoned mine sites. Application of appropriate sampling or analytical methods is very important as it affects the costs, time, and accuracy of the refined investigation of soil contamination. Two-time sampling for each crop field was conducted to verify the reproducibility of a zigzag method for soil sampling. The soil analysis using a portable X-ray fluorescence (pXRF) device was conducted to measure concentrations of metal species in soils, and its results were compared to the extracted concentrations by the Korean Standard Test (KST) for soils. As a result, the determination coefficient (R (2)) of linear regression analysis for data obtained by ex situ precise measurement or in situ field screening using pXRF was closely related with the ratio of the extracted concentration by KST to interference-free detection limits (IFDL) of pXRF (designated as KST/IFDL). As the specific metal species had a higher ratio of KST/IFDL, its R (2) was even higher in the field screening tests. However, the slopes of linear regression analysis for most metal species extracted by aqua-regia were close to 1.0 so that extracted concentrations by aqua-regia were similar to the analytical values obtained by pXRF, whereas extraction using a weak acid (0.1 M HCl) had different slopes for soils contaminated with different ranges of concentrations of metal species. Especially Zn showed not only high ratios of KST/IFDL because of aqua regia extraction, but also high determination coefficients. Because of its simple, rapid, and accurate capacities for metal analysis, the pXRF analysis showed high applicability in ex situ precise measurements or in situ field screening of metal analysis. In terms of applicability for regulation, especially in situ pXRF field screening with the zigzag method could be effectively applied to achieve an economical survey by determining hot spots or non-contaminated areas if aqua-regia was applied as the extracting agent in the KST for soils.

Selenium and other trace elements in phosphate rock of Bayovar–Sechura (Peru)

Selenium is an essential trace element in regard to human and other animals' health, but it presents a narrow range of dietary deficiency and toxic excess. Some phosphate rocks are rich in selenium. Furthermore it is necessary to control selenium's and other trace elements’ compositions in the phosphate rocks, because phosphorite ores of different geographical sites are varied, and even ores from the same outcrop can vary substantially in trace element levels. Data of trace element composition of phosphorites from Bayovar–Sechura (Northern, Peru, 06°05'S and 80°50'W) is scarce and incomplete. In this paper 19 trace element concentrations are reported. Aqua regia extracts were used to estimate the “pseudototal” values of 19 elements, following standard procedures (ISO 11466, 2002) and measured by ICP-AES and ICP-MS. In decreasing order of mean abundance (mg kg − 1 ) are: Sr (1117) > Cr (134) > B (76.8) > Zn (65.4) > V (49.2) > U (44.9) > Mo (30.4) > Cd (17.3) > Cu (17.0) > Ni (16.8) > Co (15.4) > As (14.3) > Pb (5.8) > Se (2.4) > Th (2.2) > Sn (0.81) > Sb (0.63) > Tl (0.43) > Ag (0.22). The concentration (mg kg − 1 ) of Se in Bayovar–Sechura phosphorites is: mean 2.4 ± 1.2, median 2 and range 0.5–6. Selenium is enriched in the phosphorite (factor 4). Selenium shows significant positive correlations with As, B, Cr, Mo, Sr, Th and U, and negative with Ag, Sn and Tl. Cadmium concentration (mg kg − 1 ) is: 17.3 ± 10.9, median 8.5 and range 2–53. These levels are analogous to those of average phosphorites. Uranium and Th concentrations (mg kg − 1 ) are 44.9 and 2.2, respectively, versus 120 and 6.5 of the average phosphorites. Molybdenum level (mg kg − 1 ) is a high 30.4 versus 9 of average phosphorite. This concentration is very useful in Mo deficient soils application.

Evaluation of phosphorus mobility in soil using different extraction methods

Soil samples (from Czech and German long-term field experiments) were used to estimate different soil phosphorus (P) fractions. More than 200 topsoil (0–30 cm) samples from different fertilizing treatments were taken. These were analyzed for P in soil solution (P&lt;sub&gt;CaCl2&lt;/sub&gt;) [0.01M CaCl&lt;sub&gt;2&lt;/sub&gt; extract], exchangeable sorbed P (P&lt;sub&gt;ex&lt;/sub&gt;) [anion exchange (AE) membranes] and bioavailable P [Doppel-Lactat and Mehlich 3 (P&lt;sub&gt;DL&lt;/sub&gt; and P&lt;sub&gt;M3&lt;/sub&gt;)]. Other fractions analyzed were total inorganic (P&lt;sub&gt;in&lt;/sub&gt;), total (P&lt;sub&gt;M-tot&lt;/sub&gt;) and organic (P&lt;sub&gt;org&lt;/sub&gt;) P [fractionation after Marks], P sorbed on Fe and Al (P&lt;sub&gt;FeAl&lt;/sub&gt;) [fractionation after Schwertmann] and residual P (P&lt;sub&gt;ar&lt;/sub&gt;) [aqua regia extract]. Comparison of medians appeared to be better for evaluating extraction abilities. Phosphorus fractions were in the following order: (P&lt;sub&gt;ar&lt;/sub&gt; = 100%); P&lt;sub&gt;CaCl2&lt;/sub&gt; (0.2%) &lt; P&lt;sub&gt;ex&lt;/sub&gt; (9%) &lt; P&lt;sub&gt;DL&lt;/sub&gt; (10%) &lt; P&lt;sub&gt;M3 &lt;/sub&gt; (16%) &lt; P&lt;sub&gt;in&lt;/sub&gt; (24%) &lt; P&lt;sub&gt;org&lt;/sub&gt; (37%) &lt; P&lt;sub&gt;FeAl&lt;/sub&gt; (55%) &lt; P&lt;sub&gt;M-tot&lt;/sub&gt; (59%). Low amounts of P&lt;sub&gt;in&lt;/sub&gt;, P&lt;sub&gt;org&lt;/sub&gt; and P&lt;sub&gt;M-tot&lt;/sub&gt; did not verify the applicability of the Marks’ fractionation for the set of studied soils. Close correlations at &lt;I&gt;P&lt;/I&gt; ≤ 0.001 were found for all methods for estimating the fractions of bioavailable phosphates (P&lt;sub&gt;CaCl2&lt;/sub&gt;, P&lt;sub&gt;ex&lt;/sub&gt;, P&lt;sub&gt;DL&lt;/sub&gt; and P&lt;sub&gt;M3&lt;/sub&gt;). Statistically significant relations were observed between P&lt;sub&gt;in&lt;/sub&gt; with P&lt;sub&gt;ar&lt;/sub&gt;, P&lt;sub&gt;M-tot&lt;/sub&gt; and P&lt;sub&gt;FeAl&lt;/sub&gt;.

Partitioning and mobility behavior of metals in road dusts from national-scale industrial areas in Korea

In this study, we investigated the characteristics of heavy metal contamination in road dusts collected from industrial areas in Korea. A total of 12 sampling sites, including nine sites in three different industrial complexes (ICs), two IC vicinity areas and one background area, were selected for this study. The collected road dusts were divided into four categories. The heavy metals (Cd, Cu, Pb, Zn, and Ni) were extracted from the road dust by an aqua regia extraction method and analyzed by atomic absorption spectrometry. The highest concentrations of Cd, Cu, and Pb were identified in road dusts from areas near the non-ferrous metal IC, followed by those from the petrochemical IC. The petrochemical IC and the mechanical/shipbuilding IC showed the highest concentrations of Ni and Zn in their road dusts, respectively. The concentration of heavy metals in the road dusts collected from the IC vicinity areas, even those located in a rural environment, were very high. The concentration of heavy metals increased with decreasing particle size of the road dusts. This study also analyzed the mobility of the heavy metals in the road dusts using partial sequential extraction with the Tessier procedure. The order of mobility identified, based on exchangeable and carbonate fractions of the heavy metals, was Cd > Zn > Pb > Cu > Ni.

Monitoring the Variability of Nitrogen and Cadmium Concentrations in Soils and Irrigation Water in the Almyros Area of Central Greece

The main purpose of this investigation was the monitoring of nitrogen (N) and cadmium (Cd) levels in soils and irrigation water samples in an intensively cultivated area in central Greece. From 2005 to 2007, soil as well as irrigation water samples were collected two periods a year (March and October) at the same sampling sites in the Almyros area. Nitrogen was measured in three forms (as nitrate, nitrite, and ammonium) using the anion chromatography method. Available and total Cd concentrations were measured using atomic absorption spectroscopy, after extraction with diethylenetriaminepentaacetic acid (DTPA) and aqua regia extraction solutions, respectively. The nitrate, nitrite, ammonium, and Cd concentrations were always less than the corresponding water standards. Cadmium concentration (total and DTPA extractable) in soil samples was high in the sites where phosphate fertilizers had been intensively used for the crops. Seasonal variation was found in all parameters measured between the autumn and spring of each year. No temporal variation was found, as there was no statistical difference in nitrate, nitrite, and ammonium or in Cd concentration among the years of the study. A spatial variation was observed in all the parameters and was illustrated by the respective thematic maps. Thematic maps of predictions of the measured variables, as well as for pH and electrical conductivity, were generated using geostatistics as a helpful tool in sustainable soil management of the study area. The spatial variability of available Cd was found to follow the variability of soil pH, as highly available Cd concentration was observed in highly acid soils. Significant correlations among nitrate, nitrite, ammonium, available and total Cd, and soil physicochemical parameters were obtained and discussed.

Geochemical baselines in relation to analytical methods in the Itä-Uusimaa and Pirkanmaa regions, Finland

ABSTRACT Geochemical baselines of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, V and Zn concentrations were investigated for two Finnish regions (Ita-Uusimaa and Pirkanmaa) using different determinations based on separate analytical methods: (1) total concentrations based on X-ray fluorescence (XRF) spectrometry or strong acid leach; and (2) ‘near-total’ concentrations determined using aqua regia extraction (ISO 11466) and/or concentrated nitric acid leaching (US EPA 3051A). The geology of the Ita-Uusimaa region is dominated by late-orogenic plutonic rocks, while the bedrock in Pirkanmaa contains arc-type volcanic and sedimentary rocks and turbiditic greywackes. Topsoil (0–25 cm) and subsoil samples that were analysed represent the most common mineral soil parent material types of the study regions: sandy soils, glacial till and clayey soils. The normative mineral composition of the samples was estimated using the NORMA model. The regional baseline as an estimate of the upper limit of background variation was defined in two study areas from acid-leachable concentrations. Baselines concentrations of As, Co, V and Zn exceed the Finnish soil contamination trigger values in the study areas. Regional baselines defined for one region could not be applied in another test region. Statistical tests were carried out to indicate the significance of the differences between studied baseline concentrations determined using aqua regia extraction and concentrated nitric acid leaching. The differences were found to be highly significant for As, Pb and Sb while for Cd, Co, Cr, Ni and Zn the two analytical methods were comparable. The ratios between total and ‘near-total’ (aqua regia or nitric acid-extractable) concentrations reveal higher total concentrations determined by XRF spectrometry compared to acid-leachable contents for most inorganic elements. Lead and Cr show the lowest extractability using aqua regia, while Cu was most extractable using acid leaching. According to normative mineralogy, the levels of several trace elements determined by near-total, partial methods are controlled by the abundance of micas, goethite and hydrous Al silicates. In topsoil, organic carbon correlated with Hg, Pb and Cd concentrations.

Palladium–citric acid–ammonium fluoride as a matrix modifier for overcoming of interferences occurring during the direct determination of Sn in aqua regia extracts from environmental samples by D 2-ETAAS

When tin is to be determined in such a complex matrix like aqua regia extracts of environmental samples by electrothermal atomic absorption spectrometry (ETAAS), spectral interferences occur when deuterium-lamp (D 2) background correction is used, even using high pyrolysis temperature of 1400 °C achieved with palladium with citric acid chemical modifier. We have found that the further addition of NH 4F to palladium with citric acid chemical modifier is essential for overcoming the above-mentioned problems for which aluminium oxide is most probably responsible. It is supposed, that NH 4F enables volatilization of the alumina matrix formed by hydrolysis from the chloride salt and interfering in a gas phase via the formation of AlF 3 which could be, in contrast to aluminium oxide, removed from the graphite furnace during the pyrolysis stage. Using the proposed chemical modifier, the direct and accurate determination of Sn in aqua regia extracts from rocks, soils and sediments is possible even when using matrix free standard solutions. This presumption was confirmed by the analysis of certified reference samples and by the comparison with inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS) method. Characteristic mass and LOD value for the original sample (10-μL aliquots of sample) was 17 pg and 0.055 μg g −1, respectively.