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1.
Heavy metal pollution and their fractionations in the sediments of Changjiang River in Nanjing Reach was monitored for cadmium (Cd), lead (Pb), zinc (Zn), chromium (Cr), and copper (Cu). Moreover, the biological enrichment of metals by riverine plants was studied. The results demonstrated there were highly significant variations among different sampling stations for the concentrations of tested metals. The highest range was for Cu (38.8–120.4 mg kg−1), followed by Cr (74.4–120.0 mg kg−1), Zn (80.9–121.1 mg kg−1), Ni (26.0–55.5 mg kg−1), Pb (15.8–46.7 mg kg−1) and Cd (0.28–0.48 mg kg−1). Cd was the element with highest biological enrichment factor (BEF). The highest BEF of Cd in Erigeron bonariensis reached 3.0, indicating a significant Cd enrichment in this aquatic plant. In addition, 60% of Cd was found in reducible fraction and exchangeable and acid-soluble fraction, which was consistent with its high mobility. The consistency of Cd fraction in sediment and suspended particle indicated they came from the same source. Accumulated Cd concentration calculated according to the release curve showed significant relativity with the total Cd concentration in the sediment.  相似文献   

2.
The Sarcheshmeh copper mine smelter plant is one of the biggest copper producers in Iran. Long-time operation of about 25 years of the smelter plant causes release of potentially toxic heavy metals into the environment. In this paper, geochemical distribution of toxic heavy metals in 28 soil samples was evaluated around the Sarcheshmeh smelter plant. Soils developed over the nonmineralized and uncontaminated areas have an average background concentration of 41.25 mg kg−1 Cu, 26.6 mg kg−1 As, 12.7 mg kg−1 Pb, 0.9 mg kg−1 Sb, 1.9 mg kg−1 Mo, 1.7 mg kg−1 Sn, 0.2 mg kg−1 Cd, 0.15 mg kg−1 Bi, 235 mg kg−1 S and 73.4 mg kg−1 Zn, respectively. As a result of smelting process, the upper soil layers (0–5 cm) were polluted by Cu (>1,397 mg kg−1), Cd (>3.42 mg kg−1), S (>821 mg kg−1), Mo (>10.3 mg kg−1), Sb (>11.7 mg kg−1), As (>120.6 mg kg−1), Pb (>83.8 mg kg−1), Zn (>214.9 mg kg−1), and Sn (>3.7 mg kg−1), respectively. These values are much higher than the normal concentration of the elements in the uncontaminated soil layers. The elemental values decrease with distance travelled away of the smelter plant, especially at minimum wind direction. Furthermore, high contaminated values of Cu (8,430 mg kg−1), As (500 mg kg−1), Pb (331 mg kg−1), Mo (61 mg kg−1), Sb (56.2 mg kg−1), Zn (664 mg kg−1), Cd (17.2 mg kg−1), Bi (13.4 mg kg−1), and S (3,780 mg kg−1) were observed in the upper soil layers close to the smelting waste dumps. Sequential extraction analysis shows that about 270 mg kg−1 Cu, 28 mg kg−1 Pb, 50.33 mg kg−1 Zn, and 47.84 mg kg−1 As were adsorbed by Fe and Mn oxides. The carbonate phases include 151 mg kg−1 Cu, 28 mg kg−1 Pb, 25 mg kg−1 Zn, and 32.99 mg kg−1 As. Organic matter adsorbed 314.6 mg kg−1 Cu and 29.18 mg kg−1 Zn.  相似文献   

3.
Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg−1, Pb: 28.5–67.3 mg kg−1, Zn: 17.0-65.4 mg kg−1, Cu: 21.1–51.9 mg kg−1, Ni: 27.8–40.2 mg kg−1) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.  相似文献   

4.
Physiological responses and metal accumulation in Vallisneria spiralis L. exposed to copper and cadmium contaminated sediment were examined at different metal concentrations and the influence of humic acids on copper and cadmium accumulation was also studied. The plants of V. spiralis accumulated high amount of copper and cadmium. The maximum accumulation of 396 and 114 mg kg−1 DW copper were found in the roots and shoots, respectively, at 614 mg kg−1 DW after 21 days’ copper exposure; they were 63.8 and 48.0 mg kg−1 DW for cadmium at 88.69 mg kg−1 DW. The plants showed decrease in chlorophyll content with the increasing concentration of copper/cadmium in sediment. With addition of humic acids from 3.09 to 7.89 g kg−1 DW, both copper and cadmium accumulation in V. spiralis were significantly inhibited (p < 0.01). The cadmium concentrations of roots and shoots of plant decreased 26.4–50.3 and 14.3–33.0% under cadmium treatments, respectively; copper accumulation decreased much more with 44.0–77.0 and 35.0–62.7%, respectively. It was concluded that V. spiralis appeared to be an ideal candidate for the phytoremediation of copper and cadmium polluted sediments, and humic acids had an important role in regulating copper and cadmium bioavailability and toxicity in sediments.  相似文献   

5.
Drilling fluids are used for drilling natural gas, oil and water wells. These spill over into the surrounding soil at the point of drilling, which may impair soil health. A laboratory investigation was carried out to determine the effect of non aqueous drilling fluid (NADF) and synthetic base oil used with it on soil health as indicated by the dehydrogenase activity. A non-sterile sandy loam soil was treated with different amounts of NADF and base oil at a rate of 800, 8,000 and 16,000 mg kg−1. Initially, reduction in dehydrogenase activity was observed, but it increased with the incubation time. On the 60th day of incubation dehydrogenase activity in untreated control was 1.04 mg TPF g−1 h−1 whereas in the soil samples treated with NADF and the base oil (16,000 mg kg−1), the activity was 1.53 mg TPF h−1 and 1.90 mg TPF h−1, respectively, which was 72 and 82% more than in untreated control. Base oil-treated soil showed more dehydrogenase activity than that observed with NADF. Both NADF and base oil stimulated the soil dehydrogenase activity.  相似文献   

6.
A field survey was conducted to identify potential hyperaccumulators of Pb, Zn or Cd in the Beichang Pb/Zn mine outcrop in Yunnan Province, China. The average total concentrations of Pb, Zn, and Cd in the soils were up to 28,438, 5,109, and 52 mg kg−1, respectively. A total of 68 plant species belonging to 60 genera of 37 families naturally colonizing the outcrop were recorded. According to metal accumulation in the plants and translocation factor (TF), Silene viscidula was identified as potential hyperaccumulator of Pb, Zn, and Cd with mean shoot concentrations of 3,938 mg kg−1 of Pb (TF = 1.2), 11,155 mg kg−1 of Zn (TF = 1.8) and 236 mg kg−1 of Cd (TF = 1.1), respectively; S. gracilicanlis (Pb 3,617 mg kg−1, TF = 1.2) and Onosma paniculatum (Pb 1,837 mg kg−1, TF = 1.9) were potential Pb hyperaccumulators. Potentilla griffithii (Zn 8,748 mg kg−1, TF = 1.5) and Gentiana sp. (Zn 19,710 mg kg−1, TF = 2.7) were potential Zn hyperaccumulators. Lysimachia deltoides (Cd 212 mg kg−1, TF = 3.2) was a potential Cd hyperaccumulator. These new plant resources could be used to explore the mechanisms of Pb, Zn and/or Cd hyperaccumulation, and the findings could be applied for the phytoremediation of Pb, Zn and/or Cd-contaminated soils.  相似文献   

7.
The Cu–Co–Ni Texeo mine has been the most important source of Cu in NW Spain since Roman times and now, approximately 40,000 m3 of wastes from mine and metallurgical operations, containing average concentrations of 9,263 mg kg−1 Cu, 1,100 mg kg−1 As, 549 mg kg−1 Co, and 840 mg kg−1 Ni, remain on-site. Since the cessation of the activity, the abandoned works, facilities and waste piles have been posing a threat to the environment, derived from the release of toxic elements. In order to assess the potential environmental pollution caused by the mining operations, a sequential sampling strategy was undertaken in wastes, soil, surface and groundwater, and sediments. First, screening field tools were used to identify hotspots, before defining formal sampling strategies; so, in the areas where anomalies were detected in a first sampling stage, a second detailed sampling campaign was undertaken. Metal concentrations in the soils are highly above the local background, reaching up to 9,921 mg kg−1 Cu, 1,373 mg kg−1 As, 685 mg kg−1 Co, and 1,040 mg kg−1 Ni, among others. Copper concentrations downstream of the mine works reach values up to 1,869 μg l−1 and 240 mg kg−1 in surface water and stream sediments, respectively. Computer-based risk assessment for the site gives a carcinogenic risk associated with the presence of As in surface waters and soils, and a health risk for long exposures; so, trigger levels of these elements are high enough to warrant further investigation.  相似文献   

8.
We investigated the effects on phosphorus (P) release of the addition of potato, wheat, and sunflower residues and fruit compost to five calcareous soils. Residue was added at the rate of 20 g kg−1. After 2 months of incubation, P values in control and amended soils were used for kinetic studies and fractionated by a sequential extraction procedure. The relative contribution of available P fraction (KCl-P) increased from 1.4% in control soils to 1.8%, 1.9%, 2.2%, and 2.3% in soils amended by fruit, wheat, potato, and sunflower residue addition, respectively, indicating that organic residues increased P in this fraction. In soils amended with different residues, the percentage of Olsen-P released over 86-h successive extractions with 0.01 M CaCl2 ranged from 57.6% for fruit residue addition (average of five soils) to 60.5% for potato residue addition. The ability of residues to release P depended on the soil properties, with 21.9 mg kg−1 (average of all residues) released to soil 2 and 77.4 mg kg−1 released to soil 4. Also residues behaved differently, with 31.5 mg kg−1 (average of five soils) released by fruit residues and 40.0 mg kg−1 released by sunflower residues. Release of P was best described by a parabolic diffusion model. The corresponding rate constant (mg kg−1 h−1/2) for P release for amended soils, defined as the release rate averaged for five soils, was found to decrease in the order: potato (2.73) > sunflower (2.61) > wheat (2.56) > fruit (2.50). The present study demonstrates that addition of residues improves P availability of these calcareous soils by increasing extractable P and the release rate and could be an alternative, indigenous source of P. However, the increase in P availability and the release rate following organic residue application suggests high potential mobility to water sources.  相似文献   

9.
In a typical modern agricultural Zone of southeastern China, Haining City, 224 topsoil samples were collected from paddy fields to measure the total concentrations of copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), mercury (Hg), arsenic (As) and cobalt (Co). The total concentrations ranged from 15.30 to 78.40 mg kg−1 for Cu, 20.10 to 41.40 mg kg−1 for Pb, 54.98 to 224.4 mg kg−1 for Zn, 0.04 to 0.24 mg kg−1 for Cd, 54.90 to 197.1 mg kg−1 for Cr, 0.03 to 0.61 mg kg−1 for Hg, 3.44 to 15.28 mg kg−1 for As, and 7.17 to 19.00 mg kg−1 for Co. Chemometric techniques and geostatistics were utilized to quantify their spatial characteristics and define their possible sources. All eight metals had a moderate spatial dependency except that Pb had a strong spatial dependency. Both factor analysis and cluster analysis successfully classified the eight metals into three groups or subgroups, the first group included Cu, Zn and Cr, the second group included Cd, As and Co, and the last group included Pb and Hg. The Cu, Zn and Cr concentrations in majority samples were higher than their local background concentrations and they were highly correlated (r > 0.80), indicating that they had similar pollution source and anthropic factor controlled their spatial distribution; the Cd, As and Co concentrations in majority samples were lower than their local background concentrations, indicating that the source of these elements was mainly controlled by natural factors; the mean concentration of Pb exhibited generally low level, close to its local background concentration, the Hg concentration in about half of samples was higher than its local background concentration, and they were poor correlated with the other metals, indicating that the source of Pb and Hg was common controlled by natural factor and anthropic factor.  相似文献   

10.
Mercury (Hg) is one of the elements with increasing environmental significance. A total of 22 samples (soils, rocks and gels) were collected along a 6 km transect around the Valdeazogues River valley in the southwest of the Iberian Peninsula (Almadén, Spain). Samples were characterized by different soil types of depositional sequences associated with mining tailings, type and system tracts: 15 surface soil samples included in the transect; 3 of a Haploxerept soil profile developed on slates; 2 of quartzite and slates rocks (reference rocks in the area). Moreover, two of a gel substance (in the lower tract of the river). Soil samples were analyzed for Hg, Cu, Ni, Cr, V, Pb, Cd and As, as well as for organic matter, pH abrasion and calcium carbonate content. All samples were collected from the Almadén mining district. The level of occurrence of the elements (especially Hg) and the effect of some properties on its concentration distributions were investigated. The total mercury contents varied in the range 7,315–3.44 mg kg−1. The mean concentration of total mercury in soils and rocks was 477.03 mg kg−1dry mass. This value is very high compared to the regional background value of other areas. Only rarely is it higher than 1%: in one sample (7,315 mg kg−1) it was almost eight times in comparison with the affected zones, with a high value of 1,000 mg kg−1. Significant differences between samples were found in the total content of mercury. A large percentage of the samples registered detectable levels of V, Cr, Ni, Pb, As and Cu. Cd readings were below the detectable range for all samples tested. Cr mean concentration was 216.95 mg kg−1 (minimun concentration 86, maximun 358); V mean concentration was 119.09 mg kg−1 (minimun concentration 69, maximun 1,209); As mean concentration was 51.24 mg kg−1 (minimun 13.3 and maximun 319.4); Ni mean concentration was 45.64 mg kg−1 (minimun concentration 21.2 and maximun 125.6); Cu mean concentration was 33.25 mg kg−1 (minimun concentration 19.3 and maximun 135); Pb mean concentration was 15.19 mg kg−1 (minimun 1.12 and maximun 1013). Metal distribution generally showed spatial variability ascribed to significant anthropogenic perturbation by mining tailing type. Hg showed vertical profile characterized by surface enrichment, with concentrations in the upper layer (93.7–82.2 mg kg−1 in front of 3.4 of the rock value) exceeding, in several occasions, the background value. The results obtained denote a potential toxicity of some heavy metals in some of the studied samples. Water-soluble mercury could enter the aquatic system and accumulate in sediments. Mercury and other heavy metals contamination depended on the duration and intensity of mining activities.  相似文献   

11.
The rare earth elements (REEs) in the sediments of the Xianghai wetlands were measured by inductively coupled plasma spectrometry. The REEs accumulation rates in two sedimentation cores derived from the riparian and depressional marshes were determined by 210Pb method. The results showed that REEs concentrations in the Xianghai wetland sediments (∑REEs, 116 mg kg−1) were lower than the corresponding values in Chinese soils (181 mg kg−1) and river sediments (∑REEs, 158–191 mg kg−1). Under alkaline conditions (with pH, 8.2–10.3), the light REEs were more enriched than the heavy REEs. Cerium is the predominant element, and accounts for 30–33% of the total REEs. REEs in the depressional marsh sediments were relatively high (∑REEs, 127 vs. 104 mg kg−1), especially light REEs contents. A significantly positive correlation was found between the neighboring elements except Pr and Dy. The different types of vertical distribution of REEs between the riparian and the depressional marsh can partly result from long-term differing hydrological regimes. Generally, depressional marsh had accumulated much more REEs than riparian marsh (the mean accumulation rates of ∑REEs, 102.98 vs. 48.89 μg cm−2 year−1).  相似文献   

12.
An attempt was made to evaluate background concentrations of Cd, Cu, Pb and Zn by means of geochemical and statistical approach. As many as 753 samples taken from 51 profiles located in Eastern Poland were analysed. For the estimation of geochemical background values, direct geochemical methods and a statistical analysis for the whole population of samples were applied. Average values of heavy metal concentration in loess sediments (bedrock) as well as in profiles not affected by human activity were measured. The iterative 2σ technique and calculated distribution function were chosen as statistical methods. The resulting values (background concentrations range) were as follows: Cd 0.5–0.9 mg kg−1, Cu 5–16 mg kg−1, Pb 12–26 mg kg−1 and Zn 31–47 mg kg−1. All the methods applied gave similar results. The highest deviation of the background was noted for Cu and the lowest for Zn. The lowest values of background were obtained for loess sediments and the highest in the case of the multiple 2σ method.  相似文献   

13.
An investigation was carried out to survey the magnitude and spatial distribution of heavy metals, as well as their relation with soil series, in a valley plain in Southeastern China. Soil was sampled at 159 sites by combining a squared grid and nested sampling strategies along the transect perpendicular to the Qujiang River in Zhejiang Province, China. Total concentrations of six metals, namely Cu, Fe, Mn, Ni, Pb and Zn, were measured. Classical statistics and geostatistics were used to quantify their spatial characteristics. There was a considerable variation in many of these parameters. The total concentrations ranged from 6.8 to 29.3 mg kg−1 for Cu, 6,784 to 18,678 mg kg−1 for Fe, 94 to 385 mg kg−1 for Mn, 6.1 to 20.3 mg kg−1 for Ni, 25.0 to 49.5 mg kg−1 for Pb, and 12 to 160 mg kg−1 for Zn. Pearson correlation coefficients among total metal concentrations and selected soil properties showed a number of strong associations. By virtue of analysis of variance, a predominant influence of soil series on the spatial variability of metal concentrations was observed. All metals were spatially correlated. The semivariograms of Cu, Fe, Mn, Ni and Zn were dominated by short range correlation (600 or 700 m), and that of Pb by long range (1200 m). Block kriging maps of total metal concentrations and soil properties showed strip distributions, perpendicular to the river, in the manner similar to the soil series. Principal component analysis was run to identify common distribution patterns of heavy metals and soil properties. These results illustrate that soil series information of valley plain may be useful for developing management zones for site-specific agriculture.  相似文献   

14.
The aim of this study was to evaluate soil pollution by heavy metals in an irregular settlement built on a dumpsite. The soil samples were analyzed for Cd, Cr, Cu, Pb and Ni. None of the concentrations found for the heavy metals analyzed were higher than the established Mexican official standards for contaminated soils. The mean concentrations found for the analyzed metals were as follows: 1.4 mg kg−1 for Cd, 4.7 in mg kg−1 for Cr, 304 mg kg−1 for Cu, 74 mg kg−1 for Pb and 6 mg kg−1 for Ni. The results of the geoacummulation index values show that the site was very polluted with Cu and Pb (class 7), polluted to strongly polluted with Ni (class 4); moderately polluted to polluted with Cd (class 3), and moderately polluted with Cr (class 1). The correlation analysis shows a high correlation between Pb and Cu (r 2 = 0.98), which would be explained if the main source of the polluting heavy metals was the result of electrical wire burning to recover Copper. Principal component analysis shows three principal components. The first main component (PC1) encompasses Cr, Cd, Pb and Cu. These heavy metals most likely have their origins from the open burning of municipal solid waste, tires and wire. The other two components are encompassed by Cr (PC2) and Ni (PC3). The sources of these pollutants are more likely related to the corrosion of junk metal objects and automobile use.  相似文献   

15.
Variation of vegetation coverage and canopy height may reflect the complex spatial heterogeneity of nutrient storage and supply capacity, soil moisture, and surface hydrology in the karst terrains suffering from severe land degradation. To assess the patterns of nutrient limitation under different vegetation covers in the subtropical karst ecosystems from Guizhou province, southwestern China, topsoil and leaf samples of dominant tree species were collected in forest stand (FO), shrub stand (SH) and shrub-grass stand (SG), respectively. Nutrient concentrations of both soil and leaf were determined, and ratios of N to P and vegetation nutrient reuse capacity (VNR) calculated as well as vegetation coverage, vegetation canopy height and tree density measured across the three stands. Mean leaf N/P ratio was lowest (16.1 ± 1.4) in FO and highest (33.5 ± 3.2) in SG. Vegetation nutrient reuse increased with the decline in N and P availability in soils for these three stands. VNR of N and P ranged from 8.5 to 25.2 mg N g−1 and from 0.4 to 1.1 mg P g−1, respectively, and appeared lowest in SG (10.4 mg N g−1 and 0.5 P mg g−1 on average, respectively) and highest in FO (22.4 mg N g−1 and 0.9 mg P g−1 on average, respectively). Although there was no substantial difference in phosphorus reuse efficiencies between plant species and vegetation stands, concentrations of N and P of senesced leaves (SLs) were, respectively, found in positive correlation with the concentrations of mature leaves. The variation of VNR with elements indicated that P is cycled within vegetation much more efficiently than N across the stands. This study demonstrated that the karst vegetations were generally at P-limited or N- and P- co-limited stresses and that N/P ratio could be an effective indictor for nutrient limitation in the karst ecosystems at vegetation community level rather than at tree species level. It is proposed that phosphorus reuse by mature leaves could be an adaptation strategy by the dominant species to the low P availability in the karst soil.  相似文献   

16.
Xiamen Bay (XMB) has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1980s. To assess ecological risks and the current spatial changes of metal contaminants in bottom surface sediments, 12 samples were collected. Samples were subjected to a total digestion technique and analyzed by ICP–OES for Cu, Pb, Zn, Cr, and Cd, and by AFS for Hg and As. Among these metals, Zn had the highest values (68–268 mg kg−1), followed by Pb (27–71 mg kg−1), and lower concentrations were found for Cd (42–1,913 μg kg−1) and Hg (0–442 μg kg−1). In comparison with the average crustal abundance values, the results indicated that nearly half of the sediment samples of XMB and its adjacent areas were contaminated by Cd, Pb, Zn, and As. Furthermore, based on the modified BCR sequential extraction procedure, the chemical speciation of heavy metals (Cd, Cr, Cu, Pb, Zn, Hg, and As) in selected sediment samples were evaluated in this study. Data from BCR sequential extractions indicated that Cd posed a medium ecological risk, whereas, Cr posed low risk since its exchangeable and carbonate fractions were below 4%, and the mobility of heavy metals in XMB decreased in the order Cd > Pb > Cu > Zn > Hg > As > Cr. By applying mean effects range median quotients (mERMQ), the results showed that Yuandang Lagoon with mERMQ value >0.5 would be expected to have the greatest potential toxic risk in amphipod within XMB and its adjacent areas.  相似文献   

17.
The vertical variation of P forms in sediments of urban shallow lakes in China, Xuanwu Lake, Daming Lake and Mochou Lake, were sequentially extracted and measured with the method of SEDEX. The results indicated the TP content in the sediment profiles ranged from 371.94 to 777.25 mg kg−1 for Xuanwu Lake, 1,308.14 to 4,632.63 mg kg−1 for Daming Lake, and 995.49 to 1,860.71 mg kg−1 for Mochou Lake. The results of sequential extraction showed that Ca-P and Fe-P were the main fractions. Meanwhile, the proportions of Bio-P to TP were 35.24% for Xuanwu Lake, 29.57% Daming lake, and 25.26%, for Mochou Lake, indicating a high potential of P releasing. The content of Bio-P was significantly and positively correlated with TP (r = 0.978, P < 0.01). Lake hydrations conditions played an important role in the distribution and contents of Bio-P and TP. In the region with macrophytes, the contents of TP and Bio-P were relatively low. Physicochemical properties of sediments were significantly related to the fraction distribution and P contents, and might play an important role in controlling P activity and mobility. Moreover, Fe showed an evident influence on P fraction and the ratio Fe/P might be good indicator to the contents and composition of active P in sediments.  相似文献   

18.
Copper contamination in soils and vegetables in the vicinity of an abandoned copper mine in China was investigated. The Cu concentrations of 93 soil samples ranged from 30.4 to 3,191 mg kg−1 soil for a mean of 816.8 mg kg−1 soil. Among 15 samples from a 0 to 20-cm soil layer used for the toxicity characteristic leaching procedure (TCLP) test, the highest value of Cu-TCLP was 133.8 mg kg−1 soil and the TCLP values were positively correlated with the total Cu content of the soils. The sequential extraction of soils in the 0–20-, 20–40-, and 40–60-cm soil layers showed that Cu existed mainly in the Fe–Mn oxide fraction, sulfide/organic fraction, and residual fraction. The copper contamination of 21 species of vegetables from in situ sampling was also examined. Cu concentrations in the edible portions of Brassica chinensis and Solanum melongena were higher than the FAO/WHO standard (40 mg kg−1 DW). The health risk of copper for local inhabitants from consuming these vegetables was assessed on the basis of the target hazard quotient. Enriched concentrations of copper were also found in situ in eight cultivars of B. chinensis planted in the fields, with two levels of Cu concentration. The results showed that there is severe copper contamination in this mine area, and the pollutant in soils show a high risk of leaching into the groundwater and diffusing through the food chain.  相似文献   

19.
Simulated acidic precipitation (1:1 equivalent basis H2SO4:HNO3) at pH values of 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 7.0 were conducted using column leaching to determine impacts of simulated acid rain on phosphorus (P) leaching from a calcareous sandy loam soil over a 40-day period. Soil columns were irrigated every day to make a total of 1,061 mm, equivalent to 3.5 years of rainfall (based on average annual rainfall). Leachates were collected and analyzed for anions and cations. There was significant nonlinear correlation between the amount of P leached and the simulated acid rain (R 2 = 0.61). Losses of P from the pH 2.5 and 7.0 treatments were 1.23, and 1.32 mg kg−1, respectively. The results showed that the amount of P leached from pH 4 (1.46 mg kg−1) and 5 treatments (1.52 mg−1 kg−1) were significantly larger than other treatments. Linear equation adequately described leaching of P in different treatments. The slope (mg kg−1 day−1) in the linear equation was defined as the leaching rate and for the pH 2.5 was 0.0354, and 0.0382 and 0.0406 for pH 4.5 and 7.0, respectively. The geochemical code Visual MINTEQ was used to calculate saturation indices. Leaching of P in different treatments was controlled by rate-limited dissolution of hydroxyapatite, β-tricalcium phosphate and to some extent octacalcium phosphate. The results indicate that acid rain in calcareous sandy loam soils may pose a risk in terms of groundwater contamination with P.  相似文献   

20.
A sediment core from Guanabara Bay (Brazil) was analyzed for 210Pb dating, grain size, total organic carbon (TOC) and total nitrogen, carbon stable isotope ratio (δ13C), nitrogen stable isotope ratio (δ15N) and the metals Fe, Mn, Ni, Co, Cu, Pb, V and Zn, to assess the influence of land use changes on the aquatic system in a region for which large industrial and urban development is expected in the next few decades. To obtain baseline data for improving the monitoring of the expected increase in anthropogenic impacts from surrounding drainage basins, a multivariate analysis of data from different sediment layers was carried out to evaluate the dated sediment record. The geochemical data suggested three different sedimentary phases along the last 200 years. Before the 1880s, the highest clay and TOC contents were observed, where the C/N ratios and the δ13C values suggested a mixture of algal and terrestrial organic matter and the lowest concentrations of Co, Cu, Pb, V and Zn, for which background levels were estimated (4.6, 2.7, 14.9, 24.3 and 70.2 mg kg−1, respectively). From the 1880s to the 1950s, the metal concentrations and sand particles increased, but no change in organic matter quality was observed, reflecting a period of land use change, still without significant sewage input. After the 1950s, the sedimentation rate increased from 0.42 to 0.77 cm year−1 and increasing urban sewage input was evidenced by lower C/N ratios, higher δ15N, decrease of Fe and Mn concentrations and increased fluxes of metals and TOC, which showed a good relationship with population growth data.  相似文献   

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