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1.
This article discusses the mineralogy and geochemical characteristics of the fresh copper-flotation waste samples. The mobility of As, Cd, Cr, Cu, Ni, Pb, Tl, Zn was investigated by leaching tests. The main mineral phases identified concerned dolomite, quartz, clay minerals, feldspars, and copper-bearing minerals. Chemically, CaO and silica were dominating, along with a significant concentration of precious (Cu), refractory (Cr, Ti, V, Zr), and toxic (As, Cd, Pb) metals. Elements were bound mainly to the residual fraction and sulphides in the following order: Pb > Cu ≈ Tl > As ≈ Zn > Ni ≈ Cr > Cd. The metal mobility patterns expressed as a percentage of total concentrations, were as follows: Cd (42%) > Cr (26%)> Ni (24%) > Zn (23%) > As (22%) > Tl (20%) > Cu (18%) > Pb (2%). Those constituents were released earlier in lower pH values, although Cu, Cr, and Pb were also released in higher alkaline pH values. However, Zn release was not dependent on pH. When L/S values decreased, elements like As, Cr, Cu, Pb, and Tl were released. That process caused decrease of Cd, Ni, and Zn release.  相似文献   

2.
The Issyk-Kul Lake region is well known for its magnificent scenery and unique scientific significance. With multivariable statistical methods, the contents of several geochemical elements (Fe, Mn, V, Zn, Cr, Co, Ni, Cu, As, Mo, Cd, Sb, Tl, Pb, and Hg) and total organic matter of 61 topsoil samples were analyzed, and then, the results were used to assess the environmental factors controlling the concentrations of potentially toxic elements (PTE) in the region. The results showed that most of the elements including Fe, Mn, V, Cr, Co, Ni, Cu, As, and Sb reflected the natural state, but several PTE (Zn, Mo, Hg, Cd, Pb, and Tl) had been influenced by anthropogenic factors. Among these, Zn, Mo, Hg, and Cd were significantly correlated with the organic matter content, which suggests that agricultural soils will accumulate more PTE. From the calculations for the human risk assessment of anthropogenically derived PTE (Zn, Mo, Hg, Cd, Pb, and Tl), the risks for ingestion in this region were found to be higher than those for inhalation and dermal absorption; however, the results also suggested there are no non-carcinogenic risks for all anthropogenically influenced PTE in the current state.  相似文献   

3.
Despite several studies on metal exposure in the general population, the knowledge on the background burden of distinct metals is still sparse (e.g. Cu, In, Mn, Pb, Sn, Sr, Ta, Te). While up to date reference values exist for 16 distinct metals as Biological Reference Value (BAR) or the 95th percentile for Al, As, Ba, Be, Cd, Co, Cr, Hg, Li, Mo, Ni, Pt, Sb, Se, Tl and U respectively, the background burden of the general population for the remaining elements is unknown or yet no matter of scientific counselling. We established and validated an inductively coupled plasma triple quadrupole mass spectrometry (ICP-MSMS) human biomonitoring method (HBM), that enabled us to determine 26 metals in urine. Al, As, Ba, Be, Cd, Co, Cu, Ga, Gd, Hg, In, Li, Mo, Ni, Pb, Sb, Se, Sn, Sr, Ta, Te, Tl, V and Zn were analyzed. The method was applied to 88 urine samples collected in the ambulance of the Institute for Occupational, Social and Environmental Medicine (IASU) Aachen, Germany. Patients from two major metal processing companies (steel and copper) and a more heterogenous group of occupational exposed and non-exposed persons were defined and distinguished. HBM data from about 88, in general occupationally unexposed persons against certain metals served as a collective representing the general population in first approximation. For these the 95th percentiles are reported. Significant differences of urinary metal concentrations of the employees of the two metal processing companies compared to the third group were observed among others for Cu, Cr, Ni, Mn and are discussed, thus demonstrating the usefulness of the method for both environmental and occupational purposes.  相似文献   

4.
The fractionation and distribution with depth of Cd, Cr, Cu, Ni, Pb, and Zn in 26 soils of Northern Kentucky were determined through a sequential extraction procedure in response to environmental concerns about increasing anthropogenic inputs in a fast-paced, urbanizing area. The selected sites have not received any biosolid- or industrial-waste applications. Average total concentrations per metal in soil profiles derived from alluvial, glacial till, and residual materials ranged from 0.43 to 56.00 mg kg?1 in the sequence Zn > Ni > Pb > Cr > Cu > Cd, suggesting relatively small anthropogenic inputs. The distribution of Cu, Cr, Ni, and Zn increased with soil depth, whereas Cd and Pb remained stable, indicating a strong geological or pedogenic influence. Residual forms were most important for the retention of Cu, Zn, and Ni. Cadmium and Pb exhibited a strong affinity for the Fe-Mn oxide fraction, while Cr showed the strongest association with the organic fraction. In terms of metal mobility and toxicity potential inferred from metal concentrations in labile fractions, Cd posed the greatest risk, followed by Cr ~ Pb > Ni > Zn > Cu. Soil pH, OM, and clay content were the most important parameters explaining the partitioning of metals in labile and residual fractions, emphasizing the importance of metal fractionation in soil management decisions. Alluvial soils generally contained the highest total and labile metal concentrations, suggesting potential metal enrichment through anthropogenic additions and depositional processes. These environments exhibit the highest risk for metal mobilization due to drastic changes in redox conditions, which can destabilize existing metal retention pools.  相似文献   

5.
To ascertain the potential role of chemical elements (namely, Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr) as markers in the Parkinson's disease (PD), the elemental concentration of cerebrospinal fluid (CSF) of 42 patients with PD and 20 age-matched controls was assessed. Analyses were performed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). Significantly lower levels of Co, Cr, Fe, Pb, Si and Sn were observed in the CSF of PD patients compared with those in controls, with a percentage of depletion up to 50% for Cr and Pb. No such variations were detected for all the other elements. Results suggested that Pb, Cr, Fe were the most suitable elements to distinguish between normality and PD. Different cut-off concentrations for these elements could be tentatively proposed as a predictive tool for the PD condition.  相似文献   

6.
《Fungal biology》2020,124(3-4):174-182
There is growing evidence that mushrooms (fruiting bodies) can be suitable for biogeochemical prospecting for minerals and as indicators of heavy metal and radioactive contaminants in the terrestrial environment. Apart from the nutritional aspect, knowledge of accumulation dynamics and distribution of elements in fruiting bodies, from emergence to senescence, is essential as is standardization when choosing mushroom species as potential bioindicators and for monitoring purposes. We studied the effect of fruitbody developmental stage on the contents of the elements (Li, K, V, Cr, Mn, Mg, Co, Ni, Cu, Zn, As, Rb, Sr, Ag, Al, Cd, Sb, Cs, Ba, Pb, Tl and U) in the individual parts of the Amanita muscaria fruiting body. Elements such as K, Mg, Mn, Ni, Co, Cu, Zn and Se remained similar throughout all developmental stages studied, however for K, differences occurred in the values of caps and stipes, as expressed by the cap to stipe concentration quotient (index QC/S). The other elements quantified, i.e., Li, V, Cr, As, Rb, Sr, Ag, Al, Cd, Sb, Cs, Ba, Pb, Tl and U are considered as nonessential or toxic (with the exception of V in A. muscaria). Their accumulation in the fruiting bodies and their distribution between cap and stipe did not show a uniform pattern. Pb, Sb, Tl, Ba, Sr, Li, Rb and Cs decreased with increasing maturity of the fruitbodies, implying that translocation, distribution and accumulation in stipes and caps was not a continuous process, while V, Cr, As, Ag, Cd, and U remained at the same concentration, similarly to the essential elements. Our results for A. muscaria confirm that elemental distribution in different parts of fruiting bodies is variable for each element and may change during maturation. Soil properties, species specificity and the pattern of fruitbody development may all contribute to the various types of elemental distribution and suggest that the results for one species in one location may have only limited potential for generalization.  相似文献   

7.
Microbial mats from two ponds with different salinities from the saltern of Guerrero Negro (Mexico) points toward millimeter‐scale coherent variations in trace metal (Me) concentrations (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn). Total, HCl‐leachable and pyrite‐associated Me showed a trend of increasing concentrations with increasing depth suggesting gradual addition of reactive Me probably as a result of metal sulfide precipitation at depth. The trends in Me profiles can be ascribed to the establishment and maintenance of microzones that promote geochemical processes, bacterial population distributions, and differential mass transport within the mats. Degrees of trace metal pyritization (1 ± 1% for Zn to 24 ± 7% for Cd) as well as metals associated with the pyrite fraction (<1.4–36 ± 18 nmol g?1 for Zn and Mn, respectively) were low, as expected from a reactive Fe‐limited system like Guerrero Negro. Calculated enrichment factors showed that Ni (2.6 ± 2.1), Co (5.5 ± 4.0), Pb (9.4 ± 7.4), and Cd (57 ± 39) were, on average, enriched in the microbial mats of Guerrero Negro. Natural enrichments of Cd, Pb, and Co in sediments along the coast of Baja California and metabolical requirements of Co and Ni by the predominant cyanobacteria in the Guerrero Negro mats may explain these enrichments. Metal characteristics in microbial mats could be advantageously used as biosignatures to identify their presence in the geological record or in other planetary systems.  相似文献   

8.
Concentrations of the 18 elements, barium (Ba), beryllium (Be), bismuth (Bi), calcium (Ca), cadmium (Cd), cesium (Cs), copper (Cu), lanthanum (La), lithium (Li), magnesium (Mg), molybdenum (Mo), lead (Pb), rubidium (Rb), antimony (Sb), tin (Sn), strontium (Sr), thallium (Tl), and zinc (Zn), were determined in the synovial fluids of osteoarthritic knee joints and in the corresponding sera of 16 patients by inductively coupled plasma-mass spectrometry. Knee-joint effusions have lower elemental concentrations than their corresponding sera. For the essential elements Ca, Cu, Mg, and Zn and for the nonessential and toxic elements Ba, Be, Bi, La, and Sb, this difference was highly significant. Strong positive correlations between concentrations in effusions and sera for the essential elements Cu and Mg and for the nonessential elements Cs, Li, Rb, and Sr could be established. The grade of localized hyperperfusion of the knee region in the blood pool phase of 99mTc HDP bone scan indicating inflammation did not correlate with any elemental concentration determined. Deceased.  相似文献   

9.
Abstract

Sequential extraction or fractionation of heavy metals in the solid phase and their speciation in soil solution are important tools for assessing changes resulting from land use and/or pollution. The distribution of the various forms of Ba, Cu, Ni, Pb and Zn was evaluated in soil samples taken from a polluted area, and the speciation of cations and anions in a soil solution contaminated with automotive industry waste. We evaluated the sequential extraction and speciation of Ba, Cu, Ni, Pb and Zn in a Leptosol associated with a Cambisol and contaminated with automotive industry waste. Soil samples were collected at 0-0.2 m (a mix of soil and waste); 0.2-0.4 m (waste only), and 0.4-0.6 m (soil only) both in the polluted area and in two contiguous unpolluted areas: a sugarcane plantation and a forest fragment. Total concentrations of metals in the polluted area were above limits for intervention established by European Community regulations. Cu was mostly distributed in the residual and in the oxide-bonded fractions, except for the waste-only sample, in which the carbonate-bonded fraction was significant. Zn was concentrated in the residual and carbonate-bonded fractions, while Ba, Ni and Pb predominated in the residual fraction of the contaminated samples. Metals in the soil solution were predominantly in the hydroxyl forms, except for Ba, which was mostly in the ionic form (Ba2+).  相似文献   

10.
Høiland, K. 1995. Reaction of some decomposer basidiomycetes to toxic elements. -Nord. J. Bot. 15: 305–318. Copenhagen. ISSN 0107–055X.
Cultures of 15 decomposer basidiomycete samples were examined for resistance to Al. As, Be, Cd, Co, Cr, Cu, H, Hg2(I), Hg(II), Ni, Pb, Sn, and Zn using a micro-well technique. Aluminium was found to be slightly toxic; Be, Zn, and As moderately toxic; Cr, Cu, Sn, Co, Hg(II), Ni, Hg2(I), and Pb toxic: and Cd very toxic. Generally, the fungitoxicity rises with increasing electronegativity of the element, if we exclude As and Cd. According to the fungal reactions, the elements can be arranged into several groups with similar toxicity: The Cu-Hg2(I)-Hg(II)-Ni group, the Al-Cr-H group, and the As-Pb-Zn group. Tin is related both to the first and the second group. Beryllium, Cd, and Co occupy more isolated positions. Resistance to Hg, Ni, and Cu generally increases with the ability of the fungus to produce phenoloxidases, especially the intracellular tyrosinase. One explanation may be that these fungi decompose the substances that actually bind Hg, Ni, and Cu and hence protect them from the toxic action. Resistance to A1 and H (expressed as pH) may be higher in fungi from poor soils. The physiological effect of soluble A1 on fungi seems to depend more on its ability to release H3O+ in the medium than on the toxic action of the metal itself. On the other hand, resistance to Cd is possibly higher in fungi from rich soils, probably because toxicity of Cd usually increase with pH.  相似文献   

11.
To investigate the impact of water impoundment on the metal contamination in sediments cores from the three tributaries of Three Gorges Reservoir (TGR), the concentrations, distribution, bioavailability, and potential risk of eight trace metals between summer and winter were analyzed using sequential analysis. The mean contents of all studied metals were higher than the geochemical background value, and were higher in summer than in winter. The results of the partitioning study indicated that Cr and Ni prevailed in the residual fraction, while a small proportion was found in the easily soluble fractions. Cu and Zn were distributed mainly in the residual and reducible fraction, while Cd and Pb were predominantly associated with non-residual fractions. These observations suggested that the most easily mobilized metals in the study area were Cd and Pb. The mean enrichment factors (EF) of Cu, Zn, Cd and Hg were higher than 1.5, revealing the potential anthropogenic inputs, whilst the EF of other metals remained within the range of natural variability. The positive correlation between non-residual Cu, Zn and Cd and their EF values further indicated that anthropogenic inputs were the potentially major contributor for the enrichment of Cu, Zn and Cd in TGR sediments. The results evaluated by both potential ecological risk index and modified risk assessment code (mRAC) of all sampling sites demonstrated the relatively high potential risk of sediment contamination effect in TGR.  相似文献   

12.
BackgroundSome raw materials applied in Fe foundry industries may contain potentially toxic elements. Thus, foundry worker’s occupational exposure is a constant health concern.MethodIn this study, 194 urine samples from foundry workers were analyzed by inductively coupled plasma mass spectrometry for biomonitoring of Al, As, Ba, Cd, Co, Cr, Cs, Cu, Fe, I, Mn, Ni, Pb, Sb, Sn, Se, U and Zn. Moreover, arsenic speciation was performed in representative samples of production sector workers (group A) and administration sector workers (group B).ResultsConcentrations of As, Pb, Cd, Cu, Cs, I, Sb in urines from group A were higher than those found for group B. Samples of group A presented Cs, Ni, Mn, Pb, U and Zn concentrations higher than values reported for exposed workers assessed by other studies. Forty-four samples from group A exceed As-reference limits. Group A had approximately seven times more inorganic As (as arsenite) and 14 times more organic As (as dimethyl As) than group B. A statistically significant difference was observed in the elemental concentration in the workers' urine by the time in the function. Moreover, alcohol consumption is probably influencing the urine concentration of As, Ba, Cd, Co, Cu, Fe, I, Se and Zn.ConclusionThe monitored foundry workers are exposed to potentially toxic elements and more attention must be given to their health. Therefore, workplace safety conditions must be improved, and constant biomonitoring is necessary to ensure workers' health.  相似文献   

13.
Iron- and sulfur-oxidizing bacteria identified as Thiobacillus ferrooxidans and T. thiooxidans were successfully enriched from various soil samples contaminated with heavy metals and organic compounds. Depending on the growth medium, the soil sample, and the type of contaminant, the indigenous isolates solubilized &gt; 50% of most of the heavy metals present in the solid sample (As, Cd, Co, Cr, Cu, Ni, V, Zn, B, Be). Leaching with T. ferrooxidans strains resulted in total extraction of Cd, Co, Cu, and Ni. With sulfur-oxidizing bacteria &gt; 80% of Cd, Co, Cu, and Zn was mobilized from rainwater sludge. Pb and Ba were not detected in the leachate, given the insolubility of their sulfate compounds. An increase in pulp density up to 20%, indicating 6.6% total organic carbon in the soil and rubble leach experiment (sample 557), did not inhibit the growth of the indigenous T. ferrooxidans strain. In view of these results, bioleaching appears to have some potential for remediation of heavy metal contaminated soils.  相似文献   

14.
Concentrations of Pb, Zn, Cd, Ni, Cu, Cr, and Mn were determined to assess the impact of automobiles on heavy metal contamination of roadside soil. Soil samples at four polluted sites and a control site were collected at a depth of 0, 2, 5, 10, 15, 20, 30?cm. A comparison of elemental levels between polluted and control sites exhibited exceptionally higher concentrations at the former sites. The Pb levels in polluted sites varied from 70 to 280.5?µgg?1and it rapidly decreased with depth. Similarly, mean concentrations of Zn, Cd, Ni, Cu, Cr, and Mn were significantly higher at polluted sites and followed a decreasing trend with the increase in depth. Correlation coefficients between heavy metals and traffic density were positively significant except for nickel. Profile samples showed that Pb, Zn, Cd, Cu, and Mn were largely concentrated in the top 5?cm confirming airborne contamination. The vertical movement and partitioning of metals, except Ni and Cr, exhibited predominant association with soil pH and organic carbon. The results have been presented using Heavy Metal Index.  相似文献   

15.
Abstract

Multielement (48) analysis was carried out of various fish species collected from river Buriganga, the most polluted river in Bangladesh to assess human health risk by toxic elements. Sixteen elements that is, Be, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Hg, Pb, Bi, and U, were taken into account due to their toxicities on human health. Results show that concentrations of elements in various fish species were higher in winter than those in monsoon. Among 16 elements, Mn, Cu, Zn, Cd, Ba, Pb were above Food Safety Guideline in some fishes in winter. THQ and TTHQ/HI values were less than 1 for all fishes in monsoon while THQ and TTHW/HI values were more than 1 for most of fishes in winter. These results suggesting non-carcinogenic health hazard through consumption of contaminated fishes. Only As showed low cancer risk while no cancer risk was observed for other toxic elements in monsoon. In winter, Pb showed only moderate cancer risk for Mystus vittatus (site-7) while for other fishes low cancer risk was found by Pb. It can therefore be concluded that there is human health risk in consuming of fishes collected from river Buriganga especially in winter.  相似文献   

16.
There have been few investigations of trace elements in the urine and hair of populations exposed to high levels of arsenic (As) in drinking water. Therefore, concentrations of selected metals in urine and hair samples from a population in a study area where arsenism was endemic and a control area were determined. It was found that the median concentrations of barium (Ba), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), zinc (Zn), and As in the urine samples from the population in the study area were 3.87, 0.47, 0.50, 61.84, 26.82, 1.33, 128.45, 7.05, 1.10, 233.75, and 339.63 μg/L, respectively. The corresponding values in the urine samples from a population in the control area were 29.08, 0.19, 0.21, 27.77, 10.32, 4.61, 14.01, 2.19, 3.90, 113.92, and 20.28 μg/L, respectively. In the study area, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn excreted in the urine were likely to be mainly derived from drinking water with high levels of arsenic. The median concentrations of Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Zn, and As in the hair samples from the study area were 4.16, 0.03, 0.09, 1.09, 6.54, 1.97, 0.06, 0.53, 1.64, 144.28, and 1.67 mg/kg, respectively. The corresponding values from the control area were 4.76, 0.03, 0.02, 1.41, 8.31, 1.34, 0.07, 0.39, 0.86, 154.58, and 0.29 mg/kg, respectively. Significant positive correlations were observed between As and Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn in the urine in the study area. However, As was not positively associated with these metals in the hair samples. Exposure to high levels of As in drinking water increased the accumulation of Ba and Mn in the hair and the excretion of Cd, Cu, and Mo in the urine in the study area. The population in the study area might experience Cu and Mo deficiencies for an increasing excretion of Cu and Mo.  相似文献   

17.
The geochemical partitioning of trace metals in sediments is of great importance in risk assessment and remedial investigation. Selected factors that may control the partitioning behavior of Cu, Pb and Zn in non-sulfidic, estuarine sediments were examined with the use of combined sorption curve—sequential extraction analysis. This approach, which has not been previously used to examine estuarine sediments, allowed determination of sorption parameters for Cu, Pb and Zn partitioning to individual geochemical fractions. Partitioning behavior in sulfidic sediments was also determined by sequentially extracting Cu, Pb, and Zn from synthetic sulfide minerals and from natural sediment and pure quartz sand after spiking with acid-volatile sulfide (AVS). Trace metal sorption to the “carbonate” fraction (pH 5, NaOAc extraction) increased with metal loading due to saturation of sorption sites associated with the “Fe-oxide” (NH2OH·HCl extraction) and “organic” (H2O2 extraction) fractions in non-sulfidic sediments. Freundlich parameters describing sorption to the “Fe-oxide” and “organic” fractions were controlled by the sediment Fe-oxide and organic carbon content, respectively. Sequential extraction of Cu from pure CuS, AVS-spiked sediment and AVS-spiked quartz sand showed that AVS-bound Cu was quantitatively recovered in association with the “organic” fraction. However, some AVS-bound Pb and Zn were recovered by the NH2OH·HCl step (which has been previously interpreted as “Fe-oxide” bound metals) in the sequential extraction procedure used in this study. This indicates that the sequential extraction of Pb and Zn in sulfidic sediments may lead to AVS-bound metals being mistaken as Fe-oxide bound species. Caution should therefore be exercised when interpreting sequential extraction results for Pb and Zn in anoxic sediments.  相似文献   

18.
A study was made of general ecology and metal accumulation in the widespread aquatic moss Rhynchostegium riparioides, (Hedw.) C. Jens. with a view to developing the use of this species as a monitor of heavy metal pollution. In order to establish a data bank for statistical analysis, samples of water and moss were taken within a 6-week period from 105 sites (10-m reaches) in Northern England from streams and rivers of diverse physical and chemical types. Analyses were made of 14 metals (Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb) in both 2-cm tips and whole plants. The same 14 metals were also measured in both total and filtrable water, together with 12 other variables. Samples of tips were easier to prepare for analysis, but had significantly (p < 0.001) lower concentrations of all metals except Na and K. Significant correlations (p < 0.001) between metal in moss and aqueous metal were found for ten metals (Na, K, Mg, Ca, Mn, Cu, Zn, Cd, Ba, Pb). Correlations between metals in moss and in water were in general similar for tips and whole plants, but much higher for tips with Na, Zn and Cd; the relationship was quite similar whether total or filtrable water was considered, with the exception of Ba where the correlation was much higher with the latter. A multiple regression was used to suggest which variables in water and/ or moss may influence accumulation of Co, Ni, Cu, Zn, Cd, Ba and Pb in the moss. For instance, the variables which had a very highly significant effect on Pb in tips were Pb, filtrable reactive phosphate and Zn in the water. A discussion is included of how the data may be used for monitoring purposes.  相似文献   

19.
鸡冠花植株内无机元素的分析研究   总被引:3,自引:1,他引:2  
用电感耦合等离子体发射光谱法(ICP-AES)测定了鸡冠花3个栽培品种的23种无机元素,即Al、Ba、Be、Ca、Cd、Co、Cr、Cu、Fe、K、Li、Mg、Mn、Mo、Na、Ni、P、Pb、Si、Sr、Ti、V、Zn。结果表明,不同品种及不同器官,其无机元素含量存在显著差异。总体上看,该种植物无机元素含量丰富,不同器官中以种子尤为突出,3个品种中以园绒鸡冠突出。  相似文献   

20.
Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.  相似文献   

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