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ABSTRACT: We studied the mobility and transport of heavy metals such as Cu, Zn, As, Cd, Cr, Ni, and Pb, from soil and soil amended with
sewage sludge to sorghum plants. The total and ethylenediaminetetraacetic acid (EDTA) extractable heavy metals in agricultural
soil and untreated domestic sewage sludge (DWS) samples were determined. The correlation between the total and extractable
metals in soil and sewage sludge was investigated. The total and extractable heavy metals in soil, sewage sludge and sorghum
grain were analysed by flame and electro thermal atomic absorption spectrometer (FAAS/ETAAS), after digestion in microwave
oven. Statistically good correlations were obtained between the total contents of all heavy metals and their respective extractable
fractions in soil and domestic wastewater sludge. Transfer factors of all heavy metals from domestic sewage sludge to sorghum
grains were determined.
Environmental Chemistry Letters 04/2012; 5(4):209-218. · 1.88 Impact Factor
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ABSTRACT: The objective of this study was to evaluate the association between trace and toxic elements zinc (Zn), cadmium (Cd), nickel (Ni) and lead (Pb) in biological samples (scalp hair, blood and urine) of smoker and nonsmoker hypertensive patients (n=457), residents of Hyderabad, Pakistan. For the purpose of comparison, the biological samples of age-matched healthy controls were selected as referents. The concentrations of trace and toxic elements were measured by atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The validity and accuracy of the methodology were checked using certified reference materials and by the conventional wet acid digestion method on the same certified reference materials and real samples. The recovery of all the studied elements was found to be in the range of 97.8-99.3% in certified reference materials. The results of this study showed that the mean values of Cd, Ni and Pb were significantly higher in scalp hair, blood and urine samples of both smoker and nonsmoker patients than in referents (P<0.001), whereas the concentration of Zn was lower in the scalp hair and blood, but higher in the urine samples of hypertensive patients. The deficiency of Zn and the high exposure of toxic metals as a result of tobacco smoking may be synergistic with risk factors associated with hypertension.
Journal of human hypertension 01/2010; 24(1):34-43. · 2.80 Impact Factor
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ABSTRACT: It was extensively investigated that a significant flux of toxic metals, along with other toxins, reaches the lungs through smoking. In present study toxic metals (TMs) (Al, Cd, Ni and Pb) were determined in different components of Pakistani local branded and imported cigarettes, including filler tobacco (FT), filter (before and after normal smoking by a single volunteer) and ash by electrothermal atomic absorption spectrometer (ETAAS). Microwave-assisted digestion method was employed. The validity and accuracy of methodology were checked by using certified sample of Virginia tobacco leaves (ICHTJ-cta-VTL-2). The percentages (%) of TMs in different components of cigarette were calculated with respect to their total contents in FT of all branded cigarettes before smoking, while smoke concentration has been calculated by subtracting the filter and ash contents from the filler tobacco content of each branded cigarette. The highest percentage (%) of Al was observed in ash of all cigarettes, with range 97.3-99.0%, while in the case of Cd, a reverse behaviour was observed, as a range of 15.0-31.3% of total contents were left in the ash of all branded cigarettes understudy.
Journal of Hazardous Materials 04/2009; 163(1):302-7. · 4.17 Impact Factor
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ABSTRACT: The aim of present study was to develop a database of arsenic (As) in lake water, ground water, sediment, soil, vegetables, grain crops and fish to evaluate the potential human health risks posed by higher level of As, in south east part of Sindh, Pakistan during 2005-2007. The total concentration of As in various samples under study was determined by electrothermal atomic absorption spectrophotometry (ETAAS). The reliability and accuracy of technique was checked by different certified reference materials. The concentration of As in lake and ground water samples exceeded the WHO guideline values. The concentration of As in lake sediment and agricultural soil samples ranged between 11.3-55.8 and 8.7-46.2 mg/kg while acid soluble As (acetic acid 0.11 mol/L) was observed in the range of 1.48-3.54 and 0.34-3.78 mg/kg, respectively. It was observed that the leafy vegetables (spinach, coriander and peppermint) contain higher As levels (0.90-1.20 mg/kg) as compared to ground vegetables (0.048-0.25) and grain crops (0.248-0.367 mg/kg) on dried weight basis. The estimated daily intake of total As in the diet was 9.7-12.2 microg/kg body weight/day.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 12/2008; 47(1):242-8. · 2.99 Impact Factor
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ABSTRACT: Multivariate statistical techniques, cluster analysis (CA) and principal component analysis (PCA) were applied to the data on water quality of Manchar Lake (Pakistan), generated during 2005-06, with monitoring at five different sites for 36 parameters. This study evaluated and interpreted complex water quality data sets and apportioned of pollution sources to get better information about water quality and to design a monitoring network. The chemical correlations were observed by PCA, which were used to classify the samples by CA, based on the PCA scores. Three significant sampling locations--(sites 1 and 2), (site 4) and (sites 3 and 5)--were detected on the basis of similarity of their water quality. The results revealed that the major causes of water quality deterioration were related to inflow of effluent from industrial, domestic, agricultural and saline seeps into the lake at site 1 and also resulting from people living in boats and fishing at sites 2 and 3.
Ecotoxicology and Environmental Safety 05/2008; 72(2):301-9. · 2.29 Impact Factor
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ABSTRACT: The mobility, availability and persistence of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in contaminated lake sediment samples were evaluated by means of sequential extraction scheme, proposed by the Community Bureau of Reference protocol (BCR). The metal content in the extracts was measured by atomic absorption spectrometry. The precision and accuracy of the proposed procedure were evaluated by using a certified reference material BCR 701. The maximum recoveries for heavy metals (HMs) were observed for all three steps of BCR protocol at 32h total shaking period instead of previously reported 51h, with p>0.05. The lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of HMs from sediment samples and it was observed that levels of water extractable HMs were low as compared to those values obtained by acid-soluble fraction of the BCR protocol.
Journal of Hazardous Materials 04/2008; 160(1):235-9. · 4.17 Impact Factor
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ABSTRACT: The concentrations of 15 elements were determined in water, sediment and tissues of fish (Oreochromis mossambicus) collected from five sampling stations of Manchar Lake in 2005 for two successive seasons, winter (WS) and summer (SS). Elements analysis was performed by atomic absorption spectrometry with flame (FAAS) and electrothermal (ETAAS) modes, using multielement standard solution. The obtained results show that, the trace and toxic elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and macronutrients (Al, Ca, K, Mg and Na) concentrations in lake water were above the recommended drinking water standards by WHO. Concentrations of Na detected in lake water in WS and SS, were in the range of 445.5-562.7 and 420.6-643.5 mgl(-1), respectively. While among toxic elements As concentration in both seasons, have been found in the range of 60.4-88.9 and 64.9-101.8 microgl(-1) respectively, these values are 6-10 times higher than the permissible limit of WHO. The mean concentrations of elements understudy in muscles of fish were found as 2.35, 1.39, 0.46, 2.3, 1517.9, 2.2, 2.4 and 188.9 mgkg(-1) for As, Cd, Cr, Cu, Fe, Ni, Pb and Zn, respectively. High accumulation of toxic elements in fish tissues is indicating that some of the metal contaminants are entering the food chain. Correlations among the variables were identified by multivariate analysis. The extraction of elements from sediments with EDTA, to predict the bioavailability of trace and toxic elements, has shown that among them As, Cd and Zn were the most bioavailable elements in lake sediment.
Chemosphere 03/2008; 70(10):1845-56. · 3.21 Impact Factor
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ABSTRACT: A large number of epidemiologic studies have been undertaken to identify potential risk factors for cancer, amongst which the association with cadmium has received considerable attention. There is compelling evidence in support of positive associations between cadmium and risk of lung cancer. In present study we measured the concentration of Cd in whole blood and scalp hair samples of 120 male lung cancer patients (smokers) and 150 controls or referents (smokers and nonsmokers) from different cities of Pakistan. Both referents and patients were of same age group (ranged 40-70 years), socio-economic status, localities and dietary habits. The scalp hair and whole blood samples were oxidized by 65% nitric acid: 30% hydrogen peroxide (2:1) ratio in microwave oven. To check the validity of the proposed method, a conventional wet acid digestion method was used to obtain total Cd concentration in certified samples of human hair BCR 397 and Clincheck control-lyophilized human whole blood. All digests were analyzed for Cd concentration by electrothermal atomic absorption spectrometer (ETAAS). The results of this study showed that the average Cd concentration was higher in the blood and scalp hair of lung cancer patients at different stages as compared to controls (p<001). The smoker referents have high level of Cd in both biological samples as compared to nonsmoker subjects. These results illustrate that the patients who continued smoking after confirmed diagnosis of lung cancer have 34.2-67.26 and 22.4-57.3% more Cd in blood samples and scalp hair than lung cancer patients who cease smoking. This study is compelling evidence in support of positive associations between cadmium, cigarette smoking and lung cancer risk.
Science of The Total Environment 01/2008; 389(2-3):270-6. · 3.29 Impact Factor
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ABSTRACT: Total aluminum, arsenic, calcium, cadmium, iron, lead, potassium, magnesium, nickel and zinc were determined in black tea by electro thermal atomic absorption spectrometry after ultrasonic assisted pseudo-digestion with mixture of acid and oxidant. All the metals were also determined in the tea infusions in order to know the percentage of each element leached into the liquor. A conventional acid digestion on electric hot plate was used to obtain total metals under study for comparative purpose. Analytical results for (Al, As, Ca, Cd, Fe, K, Mg, Ni, Pb and Zn) obtained by ultrasound assisted pseudo-digestion, and conventional wet digestion methods showed a good agreement, thus indicating the possibility of using ultrasonic assisted digestion sample preparation instead of intensive treatments inherent with the acid digestion methods on electric hot plate. The validity and accuracy of both procedures were checked by using certified sample of NIES No. 7 (Tea Leaves). Non significant differences were observed for P> 0.05 when comparing the values obtained by both methods (paired t-test). Principal component analysis (PCA) was applied in order to determine the different amount of metals as main sources of variability in the data sets and to establish the relation between samples (branded and nonbranded tea samples) and micronutrient, trace and toxic metals (variables). Hierarchical cluster analysis (HCA) was used to explore the different branded and nonbranded tea samples grouping according to the essential and toxic metals as additional information to the out put obtained by PCA.
Chemical Speciation and Bioavailability 11/2007; 19(4):163-173. · 0.40 Impact Factor
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ABSTRACT: The success of risk assessment of metal-contaminated soils depends on how precisely one can predict the bio-availability of trace and toxic metals in soil and transfer to the human food chain. A field experiment was carried out from 2004 to 2005 to evaluate the long-term effect of sewage sludge application in agricultural lands where mostly vegetables are grown. The aim of this study was to predict the uptake of Cd, Cu, Cr, Ni, Pb and Zn by different vegetables grown on agricultural soil irrigated for long period with untreated domestic waste water and sewage sludge (SIDWS) as test samples and for comparative purposes, same vegetables grown on agricultural soil irrigated with fresh canal water (SIFW), collected as control samples. A sample preparation method based on ultrasound-assisted pseudo-digestion (UASD) of soil, sewage sludge and vegetable samples in ultrasonic bath was developed. A conventional wet acid digestion method was used for comparison purposes. The EDTA-extractable metal in SIFW and SIDWS was also studied. The extracts and digests were analysed by flame atomic absorption spectrometer/electrothermal atomic absorption spectrometer (FAAS/ETAAS). Analytical results for six metals and metalloid by UASD in bath and conventional wet digestion methods showed a good agreement, thus indicating the possibility of using low mass and minimum quantity of digesting acid mixture in less time when compared with the conventional digestion method (CDM). The validation of the proposed UASD method was assessed by using certified reference materials BCR 483 and (whole meal flour) BCR 189. Recoveries ranging from 95.5 % to 102.3 % for understudied metals were obtained for different samples (soils and vegetables). The average relative standard deviation of UASD method varied between 2.3 % and 7.9 % for N = 12, depending on the analyte. The vegetables grown in SIDWS showed high level of heavy metals when compared with control samples. This investigation highlights the increased danger of growing vegetables in the agricultural land, continuously irrigated and dressed with waste water and solid sewage sludge.
Journal of Agronomy and Crop Science 05/2007; 193(3):218 - 228. · 2.43 Impact Factor
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ABSTRACT: A sample preparation method based on ultrasound-assisted pseudo-digestion of Al from Juices and soft drink samples under ultrasonic effect has been described. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of varying several variables at once. The effects of five different variables preintensification time (without ultrasonic stirring), intensification time in ultrasonic bath (UB), temperature of UB, two acid mixtures (HNO(3)-H(2)SO(4)-H(2)O(2) and HNO(3)-H(2)O(2)), on the recovery of Al have been investigated. From these studies, certain variable showed up as significant, and they were optimized by a using 2(3)+star central composite design, which involved 16 experiments. The best conditions for pseudo-digestion were as follows: a preintensification time 10min, intensification time 20min, volume of acid mixtures 3.0ml and temperature of ultrasonic bath 80 degrees C. A conventional acid digestion on electric hot plate was used to obtain total Al for comparative purpose. Final solutions obtained from both methods, were analysed by electrothermal atomic absorption spectrometry. Analytical results for the Al by ultrasound-assisted pseudo-digestion, and conventional wet digestion methods showed a good agreement, thus indicating the possibility of using ultrasonic-assisted digestion sample preparation instead of intensive treatments inherent with the acid digestion methods on electric hot plate. The procedure proposed allowed the determination of Al with detection limit (3alpha/s) 10mugl(-1).
Talanta 10/2006; 70(2):307-14. · 3.79 Impact Factor
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ABSTRACT: A rapid ultrasound accelerated sequential extraction procedure has been used to develop sequential extraction proposed by BCR protocol (the community Bureau of Reference now the European Union "Measurement and Testing Programme"). The effects of the ultrasonic treatment on the extraction of Cu, Cd, Cr, Pb, Ni and Zn from untreated sewage sludge collected from industrial site of Hyderabad city (Pakistan) were compared with those obtained from conventional sequentional extraction procedure of modified BCR protocol. In BCR method, each extraction steps takes 10h, where as with the use of compromise sonication conditions in ultrasonic bath, steps 1-3 of the sequential extraction (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication) could be completed in 30, 30 and 30 min, respectively. Extractable Cd, Cr, Pb and Ni contents were obtained by both comparable methodologies were measured by electrothermal atomic absorption spectrometry (ETAAS), while for Cu and Zn Flame atomic absorption spectrometry (FAAS) was used. The validations of both methods were compared by the analysis of certified reference material of soil amended with sewage sludge (BCR 483). According to statistical evaluation of the results, the proposed accelerated extraction method is valid alternative to conventional shaking with much shorter extraction time with p value <0.05. The overall metal recoveries in steps 1-3 (excluding residual step) were 95-100% of those obtained with the conventional BCR protocol, except for Cu extracted (91.6%) as related to indicative values of Cu in BCR 483 obtained in 1-3 steps. The results of the partitioning study of untreated industrial waste water sewage sludge, indicate that more easily mobilized forms (acid exchangeable) were predominant for Cd and Zn, in contrast, the largest amount of Pb and Cr was associated with the iron/manganese oxide and organic matter/sulphide fractions.
Chemosphere 04/2006; 63(3):411-20. · 3.21 Impact Factor
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ABSTRACT: The distribution and speciation of toxic metals in industrial wastewater sludge (IWS) was investigated. In this work, the modified BCR three-stage sequential extraction procedure was applied to the fractionation of Cr Pb Ni, and Cd in untreated industrial wastewater sludge from industrial sites in Hyderabad (Pakistan). The extracts were analyzed using electrothermal atomic absorption spectrometry. The procedure was evaluated using a certified reference material for soil mixed with sewage sludge BCR 483. The results from the partitioning study indicate that more easily mobilized forms (acid exchangeable) of Cd were dominant. The oxidizable fraction was dominant for all four toxic metals. Metal recovery was good, with <4% difference between the total metal recovered through the extractant steps and the total metal determined after microwave digestion. Lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of toxic species from IWS, and it was observed that levels of leachable toxic metals were low compared to the amount of metal extracted in the exchangeable fraction of the BCR protocol.
Analytical and Bioanalytical Chemistry 09/2005; 383(2):297-304. · 3.78 Impact Factor
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ABSTRACT: Multivariate statistical techniques, cluster analysis (CA) and principal component analysis (PCA) were applied to the data on water quality of Manchar Lake (Pakistan), generated during 2005–06, with monitoring at five different sites for 36 parameters. This study evaluated and interpreted complex water quality data sets and apportioned of pollution sources to get better information about water quality and to design a monitoring network. The chemical correlations were observed by PCA, which were used to classify the samples by CA, based on the PCA scores. Three significant sampling locations—(sites 1 and 2), (site 4) and (sites 3 and 5)—were detected on the basis of similarity of their water quality. The results revealed that the major causes of water quality deterioration were related to inflow of effluent from industrial, domestic, agricultural and saline seeps into the lake at site 1 and also resulting from people living in boats and fishing at sites 2 and 3.
Ecotoxicology and Environmental Safety.
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[show abstract]
[hide abstract]
ABSTRACT: A large number of epidemiologic studies have been undertaken to identify potential risk factors for cancer, amongst which the association with cadmium has received considerable attention. There is compelling evidence in support of positive associations between cadmium and risk of lung cancer.In present study we measured the concentration of Cd in whole blood and scalp hair samples of 120 male lung cancer patients (smokers) and 150 controls or referents (smokers and nonsmokers) from different cities of Pakistan. Both referents and patients were of same age group (ranged 40–70 years), socio-economic status, localities and dietary habits. The scalp hair and whole blood samples were oxidized by 65% nitric acid: 30% hydrogen peroxide (2:1) ratio in microwave oven. To check the validity of the proposed method, a conventional wet acid digestion method was used to obtain total Cd concentration in certified samples of human hair BCR 397 and Clincheck control-lyophilized human whole blood. All digests were analyzed for Cd concentration by electrothermal atomic absorption spectrometer (ETAAS). The results of this study showed that the average Cd concentration was higher in the blood and scalp hair of lung cancer patients at different stages as compared to controls (p < 001). The smoker referents have high level of Cd in both biological samples as compared to nonsmoker subjects. These results illustrate that the patients who continued smoking after confirmed diagnosis of lung cancer have 34.2–67.26 and 22.4–57.3% more Cd in blood samples and scalp hair than lung cancer patients who cease smoking. This study is compelling evidence in support of positive associations between cadmium, cigarette smoking and lung cancer risk.
Science of The Total Environment.
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ABSTRACT: Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extraction methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15–30 min and 60– 150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%–102%, 88.9%–104% and 81.2%–96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%–9.4% for all metals (n = 6).
Pedosphere.
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ABSTRACT: A sample preparation method based on ultrasound-assisted pseudo-digestion of Al from Juices and soft drink samples under ultrasonic effect has been described. A Plackett–Burman experimental design was used as a multivariate strategy for the evaluation of the effects of varying several variables at once. The effects of five different variables preintensification time (without ultrasonic stirring), intensification time in ultrasonic bath (UB), temperature of UB, two acid mixtures (HNO3–H2SO4–H2O2 and HNO3–H2O2), on the recovery of Al have been investigated. From these studies, certain variable showed up as significant, and they were optimized by a using 23 + star central composite design, which involved 16 experiments. The best conditions for pseudo-digestion were as follows: a preintensification time 10 min, intensification time 20 min, volume of acid mixtures 3.0 ml and temperature of ultrasonic bath 80 °C. A conventional acid digestion on electric hot plate was used to obtain total Al for comparative purpose. Final solutions obtained from both methods, were analysed by electrothermal atomic absorption spectrometry. Analytical results for the Al by ultrasound-assisted pseudo-digestion, and conventional wet digestion methods showed a good agreement, thus indicating the possibility of using ultrasonic-assisted digestion sample preparation instead of intensive treatments inherent with the acid digestion methods on electric hot plate. The procedure proposed allowed the determination of Al with detection limit (3ά/s) 10 μg l−1.
Talanta.
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[hide abstract]
ABSTRACT: It was extensively investigated that a significant flux of toxic metals, along with other toxins, reaches the lungs through smoking. In present study toxic metals (TMs) (Al, Cd, Ni and Pb) were determined in different components of Pakistani local branded and imported cigarettes, including filler tobacco (FT), filter (before and after normal smoking by a single volunteer) and ash by electrothermal atomic absorption spectrometer (ETAAS). Microwave-assisted digestion method was employed. The validity and accuracy of methodology were checked by using certified sample of Virginia tobacco leaves (ICHTJ-cta-VTL-2). The percentages (%) of TMs in different components of cigarette were calculated with respect to their total contents in FT of all branded cigarettes before smoking, while smoke concentration has been calculated by subtracting the filter and ash contents from the filler tobacco content of each branded cigarette. The highest percentage (%) of Al was observed in ash of all cigarettes, with range 97.3–99.0%, while in the case of Cd, a reverse behaviour was observed, as a range of 15.0–31.3% of total contents were left in the ash of all branded cigarettes understudy.
Journal of Hazardous Materials.
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ABSTRACT: A rapid ultrasound accelerated sequential extraction procedure has been used to develop sequential extraction proposed by BCR protocol (the community Bureau of Reference now the European Union “Measurement and Testing Programme”). The effects of the ultrasonic treatment on the extraction of Cu, Cd, Cr, Pb, Ni and Zn from untreated sewage sludge collected from industrial site of Hyderabad city (Pakistan) were compared with those obtained from conventional sequentional extraction procedure of modified BCR protocol. In BCR method, each extraction steps takes 10 h, where as with the use of compromise sonication conditions in ultrasonic bath, steps 1–3 of the sequential extraction (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication) could be completed in 30, 30 and 30 min, respectively. Extractable Cd, Cr, Pb and Ni contents were obtained by both comparable methodologies were measured by electrothermal atomic absorption spectrometry (ETAAS), while for Cu and Zn Flame atomic absorption spectrometry (FAAS) was used.The validations of both methods were compared by the analysis of certified reference material of soil amended with sewage sludge (BCR 483). According to statistical evaluation of the results, the proposed accelerated extraction method is valid alternative to conventional shaking with much shorter extraction time with p value <0.05. The overall metal recoveries in steps 1–3 (excluding residual step) were 95–100% of those obtained with the conventional BCR protocol, except for Cu extracted (91.6%) as related to indicative values of Cu in BCR 483 obtained in 1–3 steps.The results of the partitioning study of untreated industrial waste water sewage sludge, indicate that more easily mobilized forms (acid exchangeable) were predominant for Cd and Zn, in contrast, the largest amount of Pb and Cr was associated with the iron/manganese oxide and organic matter/sulphide fractions.
Chemosphere.
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ABSTRACT: The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, as an agricultural fertilizer. The agricultural soil amended with 250 g kg−1 sewage sludge with or without lime treatment was used for the growth of the common local grain crop, maize (Zea maize). The mobility of the trace and toxic metals in the sludge samples was assessed by applying a modified BCR sequential extraction procedure. The single extraction procedure was comprised of the application of a mild extractant (CaCl2) and water, for the estimation of the proportion of easily soluble metal fractions. To check the precision of the analytical results, the concentrations of trace and toxic metals in every step of the sequential extraction procedure were summed up and compared with total metal concentrations. The plant-available metal contents, as indicated by the deionized water and 0.01 mol L−1 CaCl2 solution extraction fractions and the exchangeable fraction of the sequential extraction, decreased significantly (P< 0.05) with lime application because of the reduced metal availability at a higher pH, except in the cases of Cd and Cu, whose mobility was slightly increased. Sludge amendment enhanced the dry weight yield of maize and the increase was more obvious for the soil with lime treatment. Liming the sewage sludge reduced the trace and toxic metal contents in the grain tissues, except Cu and Cd, which were below the permissible limits of these metals. The present experiment demonstrates that liming was an important factor in facilitating the growth of maize in sludge-amended soil.
Pedosphere.
