Heavy Metals in Freshly Deposited Stream Sediments of Rivers Associated with Urbanisation of the Ganga Plain,India

Freshly deposited stream sediments from six urban centres of the Ganga Plain were collected and analysed for heavy metals to obtain a general scenery of sediment quality. The concentrations of heavy metals varied within a wide range for Cr (115–817), Mn (440–1 750), Fe (28 700–61 100), Co (11.7–29.0), Ni (35–538), Cu (33–1 204), Zn (90–1 974), Pb (14–856) and Cd (0.14–114.8) in mg kg^-1. Metal enrichment factors for the stream sediments were <1.5 for Mn, Fe and Co; 1.5–4.1 for Cr, Ni, Cu, Zn and Pb; and 34 for Cd. The anthropogenic source in metals concentrations contributes to 59% Cr, 49% Cu, 52% Zn, 51% Pb and 77% Cd. High positive correlation between concentrations of Cr/Ni, Cr/Cu, Cr/Zn, Ni/Zn, Ni/Cu, Cu/Zn, Cu/Cd, Cu/Pb, Fe/Co, Mn/Co, Zn/Cd, Zn/Pb and Cd/Pb indicate either their common urban origin or their common sink in the stream sediments. The binding capacity of selected metals to sediment carbon and sulphur decreases in order of Zn > Cu > Cr > Ni and Cu > Zn > Cr > Ni, respectively. Stream sediments from Lucknow, Kanpur, Delhi and Agra urban centres have been classified by the proposed Sediment Pollution Index as highly polluted to dangerous sediments. Heavy metal analysis in the <20-μm-fraction of stream sediments appears to be an adequate method for the environmental assessment of urbanisation activities on alluvial rivers. The present study reveals that urban centres act as sources of Cr, Ni, Cu, Zn, Pb and Cd and cause metallic sediment pollution in rivers of the Ganga Plain.     

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.     

Ferti-irrigation Effect of Paper Mill Effluent on Agronomical Practices of Phaseolus vulgaris (L.) in Two Seasons

The potential of agrobased paper mill effluent (PME) as ferti-irrigant was assessed. Ferti-irrigation responses to 5, 10, 25, 50, 75, and 100% of PME doses on Phaseolus vulgaris L., cv. Annapurna, in the rainy and summer seasons were investigated. The fertigant concentrations produced changes in electrical conductivity (EC), pH, organic carbon (OC), sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), total Kjeldahl nitrogen (TKN), phosphate (PO₄^3–), sulfate (SO₄^2–), iron (Fe²⁺), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn) of the soil in both seasons. The agronomic performances of P. vulgaris increased from 5 to 25% in both seasons compared to controls. The accumulation of metals increased in soil and P. vulgaris from 5 to 100% PME concentrations in both seasons. The contamination factor (Cf) of various metals was in order of Cr > Mn > Cu > Cd > Zn for soil and Mn > Zn > Cu > Cd > Cr for P. vulgaris in both seasons after fertigation with PME. Therefore, PME can be used to improve the soil fertility and yield of P. vulgaris after appropriate dilution.     

Retention of cobalt by an oxisol in relation to the content of iron and manganese oxides

Abstract

The study aims at determining the cobalt retention properties of various soil components. Therefore, cobalt (Co) sorptions and extractions were carried out using an Oxisol sample before (untreated) and after successive removal of organic matter and active manganese (Mn) oxides (H₂O₂‐treated) and iron (Fe) oxides (H₂O₂+CBD‐treated). A synthetic goethite was included for comparison. Sorption of the four sorbents was determined over a range of Co concentrations (initially 10^‐8 M to 10^‐4 M), pH values (3 to 8) and reaction times (2 hours to 504 hours). The Co species sorbed was Co(ll), since oxygen exclusion during sorption had no effect on the amount sorbed. The pH‐dependent sorption curve (sorption edge) was shifted to lower pH at decreasing initial Co concentration and increasing reaction time. The displacements, in particular of the sorption edges corresponding to the lowest initial Co concentrations, to successively higher pH following removal of Mn oxides, organic matter and Fe oxides could be attributed to sorption onto sites of decreasing Co affinity [Mn oxides (and organic matter) > Fe oxides > kaolinite]. Extractions of sorbed Co at pH 5.5–7.5 with 2 M HCI showed that the extractability decreased with increasing sorption time and decreasing initial Co concentration. The untreated and H₂O₂‐treated soil samples retained sorbed Co at least as firmly as the synthetic goethite, whereas the H₂O₂+CBD‐treated sample (kaolinite) was clearly less effective. The results emphasized the importance of the soil Mn and Fe oxides for Co retention in soils but also the necessity of taken interior sorption sites into consideration.     

Annual and Seasonal Variations of Trace Metals in Atmospheric Suspended Particulate Matter in Islamabad, Pakistan

Total Suspended particulate matter (TSP) in urban atmosphere of Islamabad was collected using a high volume sampling technique for a period of one year. The nitric acid–perchloric acid extraction method was used and the metal contents were estimated by atomic absorption spectrophotometer. The highest mean concentration was found for Ca at 4.531 µg/m³, followed by Na (3.905 µg/m³), Fe (2.464 µg/m³), Zn (2.311 µg/m³), K (2.086 µg/m³), Mg (0.962 µg/m³), Cu (0.306 µg/m³), Sb (0.157 µg/m³), Pb (0.144 µg/m³) and Sr (0.101 µg/m³). On an average basis, the decreasing metal concentration trend was: Ca > Na > Fe > Zn > K > Mg > Cu > Sb > Pb > Sr > Mn > Co > Ni > Cr > Li > Cd ≈ Ag. The TSP levels varied from a minimum of 41.8 to a maximum of 977 µg/m³, with a mean value of 164 µg/m³, which was found to be higher than WHO primary and secondary standards. The correlation study revealed very strong correlations (r?>?0.71) between Fe–Mn, Sb–Co, Na–K, Mn–Mg, Pb–Cd and Sb–Sr. Among the meteorological parameters, temperature, wind speed and pan evaporation were found to be positively correlated with TSP, Ca, Fe, K, Mg, Mn and Ag, whereas, they exhibited negative relationships with relative humidity. On the other hand, Pb, Sb, Zn, Co, Cd and Li revealed significant positive correlations with relative humidity and negative with temperature, wind speed and pan evaporation. The major sources of airborne trace metals identified with the help of principle component analysis and cluster analysis were industrial emissions, automobile exhaust, biomass burning, oil combustion, fugitive emissions, resuspended soil dust and earth crust. The TSP and selected metals were also studied for seasonal variations, which showed that Na, K, Zn, Cu, Pb, Sb, Sr, Co and Cd peaked during the winter and remained lowest during the summer, while Ca, Fe, Mg and Mn were recorded highest during the spring.     

Assessment of Heavy Metals in Spinach (Spinacia oleracea L.) Grown in Sewage Sludge–Amended Soil

The assessment of heavy metals in spinach (Spinacia oleracea) grown in sewage sludge–amended soil was investigated. The results revealed that sewage sludge significantly (P < 0.01) increased the nutrients and heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn) in the soil. The contents of metals were found to be below the maximum levels permitted for soils in India. The most agronomic performance and biochemical components of S. oleracea were found at 50% concentrations of sewage sludge in both seasons. The contents of Cd, Cr, Cu, Mn, and Zn in S. oleracea were increased from 5% to 100% concentrations of sewage sludge in both seasons. The order of contamination factor (Cf) of different heavy metals was Mn > Cd > Cr > Zn > Cu for soil and Cr > Cd > Mn > Zn > Cu for S. oleracea plants after application of sewage sludge. Therefore, use of sewage sludge increased concentrations of heavy metals in soil and S. oleracea.     

Modelling trace metal extractability and solubility in French forest soils by using soil properties

Soil/solution partitioning of trace metals (TM: Cd, Co, Cr, Cu, Ni, Sb, Pb and Zn) has been investigated in six French forest sites that have been subjected to TM atmospheric inputs. Soil profiles have been sampled and analysed for major soil properties, and CaCl₂‐extractable and total metal content. Metal concentrations (expressed on a molar basis) in soil (total), in CaCl₂ extracts and soil solution collected monthly from fresh soil by centrifugation, were in the order: Cr > Zn > Ni > Cu > Pb > Co > Sb > Cd , Zn > Cu > Pb = Ni > Co > Cd > Cr and Zn > Ni > Cu > Pb > Co > Cr > Cd > Sb , respectively. Metal extractability and solubility were predicted by using soil properties. Soil pH was the most significant property in predicting metal partitioning, but TM behaviour differed between acid and non‐acid soils. TM extractability was predicted significantly by soil pH for pH < 6, and by soil pH and Fe content for all soil conditions. Total metal concentration in soil solution was predicted well by soil pH and organic carbon content for Cd, Co, Cr, Ni and Zn, by Fe content for Cu, Cr, Ni, Pb and Sb and total soil metal content for Cu, Cr, Ni, Pb and Sb, with a better prediction for acidic conditions (pH < 6). At more alkaline pH conditions, solute concentrations of Cu, Cr, Sb and Pb were larger than predicted by the pH relationship, as a consequence of association with Fe colloids and complexing with dissolved organic carbon. Metal speciation in soil solutions determined by WHAM‐VI indicated that free metal ion (FMI) concentration was significantly related to soil pH for all pH conditions. The FMI concentrations of Cu and Zn were well predicted by pH alone, Pb by pH and Fe content and Cd, Co and Ni by soil pH and organic carbon content. Differences between soluble total metal and FMI concentrations were particularly large for pH < 6. This should be taken into account for risk and critical load assessment in the case of terrestrial ecosystems.     

Roadside Accumulation of Heavy Metals in Soils in Franklin County,Massachusetts, and Surrounding Towns

Abstract

Metals cycle through the environment, and although many metals are required by biota, several have no known biological function and can be toxic. Metal concentrations [cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), palladium (Pd), vanadium (V), and zinc (Zn)] are surveyed with an eye toward soil chemistry, environmental and anthropogenic conditions, and potential remediation in 15 locations in and adjacent to Franklin County, MA. Road‐condition information was gathered, soil pH determined, and soils analyzed for soil metal content via a five‐phase sequential extraction and ICP‐AES analyses. Results indicate the majority of similarities are linked to soil pH and soil geochemistry, with only a few metals (Cr, Pb, and Zn) showing clear anthropogenic trends.     

Single and competitive adsorption isotherms of some heavy metals onto a light textured calcareous soil amended with agricultural wastes-biochars

This study investigated the adsorption behavior of selected heavy metals (Pb, Cu, and Ni) under single and multi-metal conditions by a light textured calcareous soil amended with plant residue biochars (corn straw, wheat straw, rice husk and licorice root pulp each at 3% w/w). The Freundlich isotherm best described the heavy metal adsorption suggesting multilayer adsorption. For all treatments under both adsorption conditions, the heavy metal adsorption capacity followed the order of Pb > Cu > Ni, which was associated with the hydrolysis constant, ionic radius, and electronegativity of these metals. Simultaneous presence of multiple metals decreased the adsorption capacity for each metal and the sequence was in the order of Ni > Pb > Cu. The corn straw biochar (CSB) had the highest adsorption capacity (Freundlich K_f (mg g^?1) for Ni = 0.23, Cu = 1.41 and Pb = 2.73) and medium distribution coefficient (K_{d medium}(L kg^?1) for Ni = 59.30, Cu = 1961.00 and Pb = 2602.00), indicating the CSB is the best treatment for stabilization of heavy metals in the soil. This was associated with the chemical characteristics of the CSB (high amounts of CaCO₃ and P) and the greatest increase in soil pH value.     

Heavy metals in the soil–plant system of the Don River estuarine region and the Taganrog Bay coast

Purpose

The aim of this work was to study the level and degree of mobility of heavy metals in the soil–plant system and to perform bioindication observations in the Don River estuarine region and the Russian sector of the Taganrog Bay coast.

Materials and methods

The objects of the study included samples of zonal soils (chernozem) and intrazonal soils (alluvial meadow and alluvial-stratified soils, Solonchak, sandy primitive soil) from monitoring stations of the Don river estuarine region and the Taganrog Bay coast, as well as their higher plants: Phragmites australis Cav., Typha angustifolia L., Carex riparia Curtis, Cichorium intybus L., Bolboschoenus maritimus L. Palla, and Rumex confertus Willd. The total concentrations of Mn, Ni, Cd, Cu, Zn, Pb, and Cr in the soils were determined by X-ray fluorescent scanning spectrometer. The concentration of heavy metal mobile forms exchangeable, complex compounds, and acid-soluble metal were extracted using the following reagents: 1 N NH₄Ac, pH 4.8; 1 % EDTA in NH₄Ac, pH 4.8; 1 N HCl, respectively. Heavy metals in plants were prepared for analysis by dry combustion at 450 °C. The heavy metal concentration in extracts from plants and soils was determined by AAS.

Results and discussion

The total contents of heavy metals in the soil may be described with a successively decreasing series: Mn?>?Cr?>?Zn?>?Ni?>?Cu?>?Pb?>?As?>?Cd. The total concentrations of As, Cd, and Zn in the soil exceed the maximum permissible concentrations levels. Contamination of alluvial soils in the estuarine zone with mobile Сu, Zn, Pb, and Cd has been revealed, which is confirmed by the high bioavailability of Cu and Zn and, to a lesser degree, Cd and Pb accumulating in the tissues of macrophytic plants. Data on the translocation of elements to plant organs have showed their predominant accumulation in the roots. Bioindication by the morphofunctional parameters of macrophytic plants (with a Typha L. species as an example) can be used for revealing the existence of impact zones with elevated contents of metals in aquatic ecosystems.

Conclusions

The results revealed that increased content of Zn, Pb, Cu, Ni, and As in soil have anthropogenic sources. The high content of Cr in the soils is related to the lithogenic factor and, hence, has a natural source.

     

Distribution of Trace Metals in Channel Sediment: a Case Study in South Atlantic Coast of Spain

Recently, Sancti Petri channel on the southwestern (SW) part of Iberian Peninsula has been experiencing urban, industrial, and vehicular expansion. Until recently, there have been only few published reports documenting the pattern of metal accumulation in this estuarine sediment. In the present study, trace metals such as Cu, Zn, Ni, Mn, Pb, Co, Cd, As, and Hg concentrations were analyzed from 69 sediment samples collected from 23 sampling sites of the Santi Petri channel. The magnitude of trace metal accumulation found as the following trend: Mn > Zn > Cu > Pb > Ni > Co > As > Cd > Hg. Spatial distribution pattern demonstrated overall decreasing trend of trace metal from Cadiz Bay mouth to the open ocean mouth, clearly correlative to the presence of anthropogenic inputs. Results of the principle component analysis (PCA) revealed that sediment metal chemistry of Sancti Petri channel is mainly regulated by the concentrations of Pb, Cu, Zn, and Ni; possible sources of those were from vehicular-related emissions. Pollution load index (PLI) and geo-accumulation index (I _geo ) indicated overall low values. The study will stimulate improvement of our understanding regarding the pattern of accumulation of metals in the coastal sediments, and the recorded values of metals in the present study can be used as suitable reference for future studies.     

Verhalten von Schwermetallen in Böden 1. Untersuchungen zur Schwermetallmobilität

Behaviour of heavy metals in soils. 1. Heavy metal mobility 158 soil samples with widely varying composition were analysed for their total, EDTA, DTPA and CaCl₂ extractable contents of Cd, Zn, Mn, Cu and Pb. By means of single and multiple regressions the relations between the different heavy metal fractions and the pH, organic carbon and clay content were considered. The correlations between the total, EDTA and DTPA extractable contents are very close, whereas the CaCl₂ extractable contents are not or only weakly correlated with these fractions. According to these statistical results the former fractions are considered to be the total quantity (total content) and the reactive quantity (EDTA and DTPA extractable contents) of the heavy metals, whereas the CaCl₂ extractable fraction represents the mobile fraction of the heavy metals in soils. The multiple regressions show that the mobile content of heavy metals is closely correlated with each of the quantity fractions and with soil pH. In the same way the proportion of the mobile fraction (in %) of the total, EDTA and DTPA extractable heavy metal content of the soil samples is closely related to the soil pH. Hereby the proportion of the mobile content of the various elements increases in the pH range 6,5 - 3 below element-specific threshold pH values (in brackets) in the order Cd (6,5) > Mn (5,7) > Zn (5,3) > Cu (4,5) > Pb (3,5). In the pH range 6,5 - 7,5 mainly Cu and to a lesser degree also Pb show an increasing mobility due to the influence of soluble organic substances.     

Characterizing trace metal adsorption on kaolinite

Adsorption of Cu(II), Zn(II), Co(II) and Cd(II) on kaolinite has been investigated at 25°C as a function of pH, concentration of the substrate, and the nature and concentration of the supporting electrolyte. The adsorption edges for three metals (Zn(II), Co(II) and Cd(II)) showed clear evidence of two distinct adsorption processes. As the pH was increased adsorption began at pH 4.5 for all metals, but the fraction of metal adsorbed at the completion of the first stage differed, the order being Zn(II)>Co(II)～Cd(II). The second stage of adsorption had characteristics similar to those for adsorption of the metals on alumina and silica. Type 1 adsorption (the first stage) probably occurs on the permanent negatively charged kaolinite faces, while Type 2 (the second stage) is associated with the variable-charge surfaces. Increasing the concentration of supporting electrolyte (KNO₃ or NaCl) dramatically reduced the extent of Type 1 adsorption: at 0.1 m no evidence of this process existed. At intermediate concentrations electrolytes containing K⁺ suppressed Type 1 adsorption more than those containing Na⁺.     

Verhalten von Schwermetallen in Böden. 2. Extraktion mobiler Schwermetalle mittels CaCl2 und NH4NO3

Behaviour of heavy metals in soils. 2. Extraction of mobile heavy metals with CaCl₂ and NH₄NO₃ 156 soil samples from arable fields, grassland and forest stands were analysed for the CaCl₂^? and NH₄NO₃^? extractable contents of Cd, Zn, Mn, Cu and Pb. The average amounts of Cd, Zn, Cu and Pb extracted with CaCl₂ are higher compared with NH₄NO₃ whereas the relation for Mn is vice versa. The proportion of the NH₄NO₃^? extractable contents in percent of the CaCl₂^? extractable contents of Cd, Zn and Pb decrease with increasing pH, whereas the contents of Mn and Cu increase. Inspite of a differing extraction behaviour of the two salt solutions the CaCl₂^? and NH₄NO₃^? extractable amounts of Cd, Mn, Zn und Pb are highly correlated and can be converted one into another. The mobile (CaCl₂, NH₄NO₃) proportion of the corresponding total, EDTA and DTPA heavy metal contents is in close relation to the pH of the soils. Using CaCl₂ solution the threshold pH values for an increasing mobility decrease in the order Cd > Mn > Zn > Cu > Pb, using NH₄NO₃ as extractant the order is Mn > Cd > Zn > Cu > Pb. In the case of CaCl₂ as extractant soluble chloro-Cd-complexes will be formed so that the Cd mobility in soils will be overestimated in most cases.     

Distribution and availability of fungicide-derived copper in soil aggregates

Purpose

Soil consists of various sizes of aggregates, and different soil aggregates vary in their abilities to adsorb or transport metals. This study aimed to investigate the distribution behaviors of Cu from different fungicides in soil aggregates after a 15-month incubation.

Materials and methods

Bordeaux mixture (CuSO₄/Ca(OH)₂?=?1/1 by weight, BR), copper nitrate (Cu(NO₃)₂·4H₂O, CN), and copper oxychloride (3Cu(OH)₂·CuCl₂, CO) were applied to a representative Chinese Mollisol to reach the Cu content 200 mg kg^?1. Five soil aggregate fractions, i.e., >?2000 μm, 2000–1000 μm, 1000–500 μm, 500–250 μm, and <?250 μm, were obtained by the wet sieving method. The modified Bureau Communautaire de Références (BCR) sequential extraction was applied to assess the Cu distribution among the main soil fractions.

Results and discussion

The highest Cu mass loading was found for the >?2000-μm soil aggregate. The input Cu was mainly in stable fractions, and the highest proportion was found for the residual fraction. The bioavailability and mobility of Cu from different fungicides in soils varied from each other, and they presented an order of CO > CN > BR. High bioavailability and transferring coefficients were found in the <?250-μm and >?2000-μm soil aggregates.

Conclusions

This study indicated that the input Cu from fungicides mainly distributed in the >?2000-μm soil aggregates. Moreover, the CO-derived Cu presented a higher availability than the BR- and CN-derived Cu in the soil.

     

Extractability and plant uptake of heavy metals in alum shale soils

Abstract

Fifty soil samples (0–20 cm) with corresponding numbers of grain, potatoes, cabbage, and cauliflower crops were collected from soils developed on alum shale materials in Southeastern Norway to investigate the availability of [cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and manganese (Mn)] in the soil and the uptake of the metals by these crops. Both total (aqua regia soluble) and extractable [ammonium nitrate (NH₄NO₃) and DTPA] concentrations of metals in the soils were studied. The total concentration of all the heavy metals in the soils were higher compared to other soils found in this region. Forty‐four percent of the soil samples had higher Cd concentration than the limit for application of sewage sludge, whereas the corresponding values for Ni, Cu, and Zn were 60%, 38%, and 16%, respectively. About 70% the soil samples had a too high concentration of one or more of the heavy metals in relation to the limit for application of sewage sludge. Cadmium was the most soluble of the heavy metals, implying that it is more bioavailable than the other non‐essential metals, Pb and Ni. The total (aqua regia soluble) concentrations of Cd, Cu, Zn, and Ni and the concentrations of DTPA‐extractable Cd and Ni were significantly higher in the loam soils than in the sandy loam soils. The amount of NH₄NCyextractable metals did not differ between the texture classes. The concentrations of DTPA‐extractable metals were positively and significantly correlated with the total concentrations of the same metals. Ammonium nitrate‐extractable metals, on the other hand, were not related to their total concentrations, but they were negatively and significantly correlated to soil pH. The average concentration of Cd (0.1 mg kg^‐1 d.w.) in the plants was relatively high compared to the concentration previously found in plants grown on the other soils. The concentrations of the other heavy metals Cu, Zn, Mn, Ni, and Pb in the plants were considered to be within the normal range, except for some samples with relatively high concentrations of Ni and Mn (0–11.1 and 3.5 to 167 mg kg‘¹ d.w., respectively). The concentrations of Cd, Cu, Zn, Ni, and Mn in grain were positively correlated to the concentrations of these respective metals in the soil extracted by NH₄NO₃. The plant concentrations were negatively correlated to pH. The DTPA‐extractable levels were not correlated with plant concentration and hence DTPA would not be a good extractant for determining plant availability in these soils.     

Association of cadmium,zinc, copper,and nickel with components in naturally heavy metal‐rich soils studied by parallel and sequential extractions

Abstract

In this study, a new parallel and sequential extraction procedure was proposed to investigate the solubility of metals [cadmium (Cd), zinc (Zn), copper (Cu), and nickel (Ni)] and their association with soil components in naturally metal‐rich soils of Norway. Two different soils, alum shale (clay loam) and moraine (loam), developed on alum shale minerals were used. Each soil had two pH levels. For parallel and successive extractions, H₂O, 0.1M NH₄OAc (soil pH), 0.3M NH₄OAc (soil pH), 1M NH₄OAc (soil pH), and 1M NH₄OAc (pH 5.0) were used. A significant amount of Cd was extracted by NH₄O Ac related to concentration of NH₄OAc in the extracting solution. The amounts of Zn, Cu, and Ni extracted by these reagents were almost negligible except with 1M NH₄OAc (pH 5.0). Thus these metals were strongly bound to soil components. A seven step sequential extraction procedure was applied to evaluate the association of metals with soil constituents. The extractions were performed sequentially by extracting the soil with reagents having an increasing dissolution strength: 1M NH₄OAc (soil pH), 1M NH₄OAc (pH 5.0), 1M NH₂OH.HCl (in 25% HOAc), 1M NH₂OH.HCl (in 0.1M HNO₃), 30% H₂O₂ (in 0.1M HNO₃), 30% H₂O₂ (1M HNO₃), and aqua regia. In both soils at both pH levels investigated, appreciable percentages of total Cd (20–50%) were found associated with the NH₄OAc extractable fraction (mobile fraction). For Zn, Cu, and Ni, the percentage of total metal extracted with NH₄OAc was low (<4%), but it increased significantly by introducing a reducing agent (NH₂OH.HCl). The NH₂OH.HCl‐extractable fraction was the greatest fraction (>60%) for all four metals examined. These results suggest that among the metals studied, only Cd was easily desorbed from soil and should be considered mobile and potentially bioavailable. Other metals (Zn, Cu, and Ni) were strongly associated with the soil components and should be considered less available to plants. Using the sequential fractionation technique as a measure of availability, mobility and potential bioavailability of these four metals in the alum shale soils were: Cd>Zn>Ni>Cu.     

Investigation of Heavy Metals using Various Extraction Methods in Livestock Manures

The use of animal waste for a soil amendment is a viable option for waste management. For safe and sustainable management of waste, it is important to assess the concentrations of heavy metals (HM). An experiment was conducted to compare metals [copper (Cu), zinc (Zn), and manganese (Mn)] in cow manure (CM), duck litter (DL), poultry litter (PL), and poultry litter ash (PLA) using eight extraction solutions. Extractability of HM was highly dependent upon the type of waste as well as extracting agent. Manures differed for the release of HM in the order of PL > DL > CM. Marked decreases in extractable trace elements were observed after ashing of PL irrespective of extraction method. Except for water, extractions released HM in the order of Mn > Cu > Zn. For Zn and Mn, the amount extracted varied in the order 1 M nitric acid (HNO₃) > 0.1 M HNO₃ > 0.01 M HNO₃ ≈ ethylenediaminetetraacetic acid (EDTA) > ammonium nitrate (NH₄NO₃) > calcium chloride (CaCl₂) > ammonium acetate (NH₄OAc) > H₂O in PL and PLA. Peak concentration of Cu was achieved in 1 M HNO₃ solution and the lowest Cu was found in NH₄OAc solution. On the basis of these results, the low extractability of HM in ash could suggest that the use of burned PL would be less of a water-pollution problem in the fields.     

Partitioning of Trace Metals in Suspended Sediments from Huanghe and Changjiang Rivers in Eastern China

Assessing metal contamination of sediments requires knowledge of the geochemical partitioning of trace metals at the sediment-water interface. Under controlled laboratory conditions, sequential extraction was conducted to determine the associations of metals (Cd, Cr, and Zn) and radiotracers (¹⁰⁹Cd, ⁵¹Cr, and ⁶⁵Zn) with various geochemical phases and the different partitioning and mobility of metals for two types of surface sediments collected from the Huanghe and Changjiang Rivers in Eastern China. The residual phase was the major phase for stable metal binding, indicating that these sediments had little subjection to recent anthropogenic influences. Fe–Mn oxides were the next important binding phases for metals. The partitioning of metals in various geochemical phases as a function of the duration of the radiolabeling was also examined. Trace metals transferred among the different geochemical phases over the 30 days radiolabeling period, particularly between the carbonate and Fe–Mn oxides phases. The freshwater-sediment distribution coefficients (K _d) of three metals were investigated in batch experiments using the radiotracer technique. The decreasing K _d with increasing metal concentration(from 0.5 to 200 μg L^-1) may be explained by competitive adsorption. The metal K _d in sediments from the Changjiang River was greater than those from the Huanghe River, presumably because of the higher Fe/Mn and organic carbon contents in Changjiang River sediment. The K _d decreased with increasing total suspended solid load from 3 to 500 mg L^-1, and was Cr > Zn > Cd. For Cd and Zn, increasing the pH from 5 to 8 resulted in an increase in K _d due to the reduced H⁺ competition and increasing sorptionpotential. However, the K _d for Cr in the sediments from both rivers showed no relationship with pH, presumably becauseof the complexity of the Cr species and environmental behavior.     

Soil extractants used in Estonia and Finland,their extraction power,and suitability for testing Estonian soils

Abstract

The present work was undertaken to obtain information on the effectiveness of extractants used for soil testing in Estonia and in Finland and to evaluate the suitability of the Finnish methods for use with Estonian soils. The sample material involved 86 soils and winter wheat (Triticum aestxvum L.) shoots collected from farmers’ fields in Estonia. The extractants used in Estonia were double lactate (DL) for phosphorus (P) and potassium (K), ammonium lactate (AL) for calcium (Ca) and magnesium (Mg), 1N HCl for copper (Cu), manganese (Mn), and zinc (Zn), ammonium oxalate (AO) for molybdenum (Mo) and 1N HNO₃ for cadmium (Cd) and lead (Pb). In Finland, acid ammonium acetate (AAAc) was used for P, K, Ca, and Mg determination, and acid ammonium acetate‐EDTA (AAAc‐EDTA) for Cu, Mn, Mo, Zn, Cd, and Pb. The order of magnitude of extractable concentrations for these elements was: P_DL > P_AAAc, K_DL < K_AAAc, Ca_AL < Ca_AAAc, Mg_AL> Mg_AAAc, Cu_HCl > Cu_AAAc‐EDTA, Mn_HCl, > Mn_AAc‐EDTA, Zn_HCl < Zn_AAAc‐EDTA, Mo_AO > Mo_AAAc‐EDTA, Cd_HNO3 > Cd_AAAc‐EDTA, and Pb_HNO3 > Pb_AAAc‐EDTA. Correlations between results of respective methods for determining macronutrients were high (r ≥ 0.9). In the case of Cu, Mn, Mo, Zn, Cd, and Pb r values ranged from 0.5 to 0.8 due to difficulties in determining low concentrations. A statistically significant correlation between concentrations of elements in soil and in wheat shoots only existed for few elements. The DL extractable P and K correlated better than those for the AAAc method, and coefficients for the DL method were 0.29 and 0.31, respectively. This indicates that the DL method is better suited to Estonian soils than the AAAc method. In the case of Cu, Mn, Mo, and Zn, no method preference was found.