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1.
The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water
for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level
of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest,
concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and
Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently,
irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements
in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol
accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were
observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in
contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0–20 and 30–50 cm). When the
same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0–20 cm; and Cr, Ni, Cu, Cd,
and Zn at 30–50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited
significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible
associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was
abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and
Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction. Generally,
a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced
lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol
and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution
of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively
elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health
threat through their introduction into the food chain in the wastewater irrigated soils. 相似文献
2.
Heavy metal content and distribution in surface sediments of the Seyhan River, Turkey 总被引:4,自引:0,他引:4
Davutluoglu OI Seckin G Ersu CB Yilmaz T Sari B 《Journal of environmental management》2011,92(9):2250-2259
Chemical fractionation of seven heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) was studied using a modified three-step sequential procedure to assess their impacts in the sediments of the Seyhan River, Turkey. Samples were collected from six representative stations in two campaigns in October 2009 and June 2010, which correspond to the wet and dry seasons, respectively. The total metal concentrations in the sediments demonstrated different distribution patterns at the various stations. Cadmium was the only metal that was below detection at all stations during both sampling periods. Metal fractionation showed that, except for Mn and Pb, the majority of metals were found in the residual fraction regardless of sampling time, indicating that these metals were strongly bound to the sediments. The potential mobility of the metals (non-residual fractions) is reflected in the following ranking: Pb > Mn > Zn > Cu > Ni > Cr in October 2009 and Mn > Pb > Zn > Cu > Ni > Cr in June 2010. The second highest proportion of metals was bound to organic matter/sulfides, originating primarily from anthropogenic activities. Non-residual metal fractions for all stations were highest in June 2010, which may be linked to higher organic matter concentrations in the sediment samples with 1.40% and 15.1% in October 2009 and June 2010, respectively. Potential sediment toxicity was evaluated using the Risk Assessment Code (RAC). Based on RAC classification, Cd and Cr pose no risk, Cu and Ni pose low risk, Pb and Zn were classified as medium risk metals, while the environmental risk from Mn was high. In addition, based on the sediment quality guidelines (SQG), the Seyhan River can be classified as a river with no, to moderate, toxicological risks, based on total metal concentrations. 相似文献
3.
This study investigated the degree to which human activities through urbanization influence heavy metal concentrations in a suburban landscape in Ankeny, IA. Residential areas from different years in nine time periods of development were identified from aerial photos. Soil cores were collected from the center of the front yard of 10 randomly selected homes. Cores were subdivided into 0- to 5-, 5- to 10-, and 10- to 20-cm increments from a composite of five cores. The soils were analyzed for organic C, pH, and total Cd, Co, Cr, Cu, Ni, Pb, and Zn. Results showed that organic C increased and pH decreased with time, and that there was a general decreasing trend in heavy metal concentrations from the pre-1939 period until 1983-1990, after which there was a sharp increase in the concentrations of most of the metals. The mean Cu concentration ranged from 21 mg kg(-1) for the pre-1939 time period of development to 14.9 mg kg(-1) for the recent period of development (2003-2005). Nickel concentrations increased significantly with depth with means of 21.3 mg kg(-1) at depth 0 to 5 cm, 22.5 mg kg(-1) at depth 5 to 10 cm, and 23.0 mg kg(-1) at depth 10 to 20 cm. The concentrations of heavy metals were significantly intercorrelated, except Zn, suggesting their coexistence as mineral constituents or common contamination source. The concentrations of Cu and Pb in some locations could be due to anthropogenic inputs or higher organic matter content in soils adjacent to older homes. There appears to have been a source that caused an increase in Cd, Cr, Co, Cu, Pb, and Ni concentrations in soil adjacent to homes built between 1983 and 1990. 相似文献
4.
柴窝堡湖表层底泥重金属污染评价 总被引:1,自引:0,他引:1
研究了乌鲁木齐市柴窝堡湖表层底泥的重金属含量,并采用Hakanson潜在生态危害指数法对底泥中的重金属潜在生态风险进行评价。结果表明:底泥中Cu、Zn、Pb、Cd含量均超出乌鲁木齐市土壤背景值。除湖心区外,Cd在5个监测区域中的潜在生态危害均为中等;其它重金属在5个采样点的潜在生态危害均为轻微。各重金属间的相关性分析表明,Zn与Cu,Pb与Cd、Cu呈显著正相关,说明这4种元素污染源可能相同。柴窝堡湖表层底泥受到Cu、Zn、Pb、Cd污染,需采取相应措施防止重金属由底泥进入水相。 相似文献
5.
Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring geochemical resources. However,
this has been enhanced by anthropogenic activities such as crude oil exploration and exploitation activities, resulting in
pollution in the Taylor Creek aquatic ecosystem. The catfish species Bagrus bayad and other environmental segments were collected from five selected sites along Taylor Creek, southern Nigeria, and total
metal concentration determined. The concentration levels of the metals in B. bayad were higher than the values reported in the literature for fresh fish and may lead to a higher risk of harmful effects. The
bivariate regression models relating metals in B. bayad and metals in the surface waters were significant (R
2 ≥ 0.9002). The log (bio-concentration factor; BCF) values of Cr and Zn in B. bayad were the highest, whereas the lowest was found for Ni. The ecological distribution of the log (BCF) values was, for all the
heavy metals, moderately stable over the creek. All log-transformed bio-magnification factors (BMF) in the creek were positive,
which indicates that the metal concentration was greater in B. bayad than in suspended particulate matter (SPM). The absolute log (BMF) values of heavy metals can, therefore, be ranked in order
of decreasing magnitude: Cr (3.26) > Zn (2.99) > Cd (2.93) > Fe (2.76) > Pb (2.66) > Mn (2.36) > Ni (2.24). This sequence
indicates that toxic metals such as Cd, Cr and Pb are undergoing significant bio-reduction from SPM to B. bayad. The degree of correlation between the metals was different in B. bayad, which suggests that the sources of the metals polluting Taylor Creek were diverse. 相似文献
6.
Characteristic levels of heavy metals in soil profiles of automobile mechanic waste dumps in Nigeria
The characteristic levels of heavy metals (Cd, Cr, Cu, Pb, Ni and Zn) of soil profiles of automobile mechanic waste dumps
were studied. The concentration of heavy metals decreased with the depth of the profile and lateral distance from the dumpsites.
The levels found in this study exceeded background concentrations and limits for agricultural and residential purposes. The
distribution pattern of heavy metals in the soil profiles were in the following order Pb > Zn > Cu > Cd > Ni > Cr. The mechanic
waste dumps represent potential sources of heavy metal pollution to environment. The elevated levels of heavy metals in these
soil profiles constitute a serious threat to both surface and groundwater. 相似文献
7.
8.
河流底泥重金属污染及潜在生态风险评价——以湘江株洲段为例 总被引:1,自引:0,他引:1
通过对湘江株洲段6个监测断面左右两岸共32个底泥样品重金属Pb,Zn,Cd,As,Hg和Cr质量比进行分析研究,并进行潜在生态风险评价。结果表明:霞湾断面是重金属富集最严重的断面;Cd,Hg和As的含量均超过GB15618—1995三级标准和长沙-湘潭-株洲3市土壤背景值;重金属含量大部分分布特征为右岸高于左岸;从重金属污染的潜在生态风险看,湘江株洲段各监测断面潜在生态风险都很高;各重金属元素对生态风险影响程度从大到小的顺序为:Hg〉Cd〉As〉Pb〉Zn〉Cr。 相似文献
9.
The distribution of some heavy metals, namely Cd, Pb, Zn, Fe, Cu, Cr and Mn in epipellic sediments of Igbede, Ojo and Ojora
rivers of Lagos was studied weekly in the early summer (November) of 2003. The levels of selected trace metals were determined
using Atomic Absorption Spectrophotometer (UNICAM 969 AAS SOLAR). Trends in heavy metal burdens in the sediments revealed
weekly variations in all the rivers assessed. Statistical analyses also showed different mean levels of trace metals in the
aquatic environments, the distribution of which followed the sequence Fe > Zn > Mn > Pb > Cu > Cr > Cd, Fe > Zn > Cu > Mn
> Pb > Cr > Cd and Fe > Zn > Mn > Cu > Cr > Pb > Cd in Igbede, Ojo and Ojora rivers respectively. Fe recorded the highest
concentration levels (1,582.95 ± 96.57 μ g/g–1,910.34 ± 723.19 μ g/g) in all the sediments investigated while the Cd levels
(0.06 ± 0.10 μ g/g–0.47 ± 0.36 μ g/g) were the lowest. Expectedly, trace metal concentrations in fine grain muddy sediments
of the Igbede and Ojo coastline were much higher than those of Ojora which consist of coarse and sandy deposits covering the
near shore area. Generally, the results obtained fell within tolerable limits stipulated by World Health Organization (WHO). 相似文献
10.
Wei Luo Yonglong Lu Yan Zhang Wenyou Fu Bin Wang Wentao Jiao Guang Wang Xiaojuan Tong John P. Giesy 《Journal of environmental management》2010,91(12):2599-2607
Concentrations of As and selected metals were determined in surface soils of the Miyun Reservoir watershed of Beijing, China. The degree to which concentrations of As and metals exceeded the corresponding background concentration of soils was: Cr > Cu > Zn > As > Ni with no apparent anthropogenic contamination with Cd and Pb. Based on the results of a combination of multivariate statistics and geostatistical analysis, greater concentrations of Cr and Ni in soils were determined to be primarily from iron ore mining near where the Chaohe River enters the northeast portion of the reservoir. Agricultural activities were responsible for the observed elevated concentrations of Cu and Zn in soils. Relatively great concentrations of As were found in soils near the upstream regions of the Baihe River in Chicheng County where small gold mining activities have taken place. The greatest potential for adverse effects of Cr and Cu occurred along the eastern shore of Miyun Reservoir. 相似文献
11.
在研究的8种重金属元素中,Cd、Cr、Cu、Pb、Zn、Ni的平均值都超过上海市土壤背景值,但均低于国家土壤环境二级标准。与上海优质农产地环境标准相比较,重金属含量平均值超过标准的有Cr、Pb、Zn,但研究区土壤中8种重金属含量的平均值均低于绿色食品产地环境技术条件和无公害食品产地环境技术条件。宝山区7个城镇农业土壤按多因子潜在生态危害指数评价,庙行镇的生态风险指数最高,月浦镇的生态风险指数最低。从宝山区农田土壤重金属含量的整体情况来看:多因子潜在生态评价值为119.08,宝山区农田土壤达到轻微生态危害。 相似文献
12.
Two pulp and paper industrial wastes, lime mud (LM) and recovery boiler ash (RB), have low moisture contents, low heavy metal contaminations and contain various carbonate compounds which contribute to a high pH. Metal finishing wastewater (MF-WW) has a low pH, high levels of TDS and high contaminations from Cr, Cu, Pb and Zn. The heavy metals from MF-WW were removed by sorption and precipitation mechanisms. LM gave better results in removing heavy metals from MF-WW than RB. At a reaction time of 45 min, the maximum removal efficiencies for Cr (93%) and Cu (99%) were obtained at 110 g L−1 of LM, but at 80 g L−1 for Pb (96%) and Zn (99%). Treatment with LM gives a higher sludge volume than with RB. However, the leachability of heavy metals from LM is lower. Leachability of heavy metals in the sediment for all selected treatment conditions is within government standards. 相似文献
13.
Environmental dredging is a primary remedial option for removal of the contaminated material from aquatic environment. Of
primary concern in environmental dredging is the effectiveness of the intended sediment removal. A 5-year field monitoring
study was conducted to assess the effectiveness of the environmental dredging in South Lake, China. The concentrations of
total nitrogen (TN), total phosphors, and heavy metals (Zn, Pb, Cd, Cu, Cr, Ni, Hg, and As) before and after dredging in sediment
were determined and compared. Multiple ecological risk indices were employed to assess the contamination of heavy metals before
and after dredging. Our results showed that the total phosphorus levels reduced 42% after dredging. Similar changes for Hg,
Zn, As Pb, Cd, Cu, Cr, and Ni were observed, with reduction percentages of 97.0, 93.1, 82.6, 63.9, 52.7, 50.1, 32.0, and 23.6,
respectively, and the quality of sediment improved based on the criterion of Sediment Quality Guidelines by USEPA and contamination
degree values (Cd) decreased significantly (paired t-test, p < 0.05). Unexpectedly, the TN increased 49% after dredging compared to before dredging. Findings from the study demonstrated
that the environmental dredging was an effective mechanism for removal of total phosphorus and heavy metals from South Lake.
Nevertheless, the dredging was ineffective to remove total nitrogen from sediment. We conclude that the reason for the observed
increase in TN after dredging was likely ammonia release from the sediment impairing the dredging effectiveness. 相似文献
14.
It has long been known that heavy metals, when in high enough concentration, have the potential to be both phytotoxic and zootoxic. Heavy metals are frequently found as contaminants in green waste. Any such waste that is subsequently segregated for composting theoretically has the potential to retain that possible contamination. To date, there have been a limited number of publications addressing this issue. Most reports have concentrated on the types of heavy metals found in compost and their acceptable levels, rather than the fate of heavy metal contaminants throughout the composting process. This investigation was aimed to identify the fate of cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb) and zinc (Zn) concentrations throughout a fourteen week composting cycle. The results of this study showed a general increase in the removal of Pb, Cu, Cr, and to a much smaller extent Zn, manifested by a decrease in their overall concentrations within the solid fraction of the final product, by 93, 49, 43, and 20 percent respectively. By contrast, there was no decrease in the overall concentration of Cd. 相似文献
15.
Inter-seasonal studies on the trace metal load of surface water, sediment and Tympanotonus fuscatus var. radula of Iko River were conducted between 2003 and 2004. The impact of anthropogenic activities especially industrial effluent,
petroleum related wastes, gas flare and episodic oil spills on the ecosystem are remarkable. Trace metals analyzed included
cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn). Sediment
particle size analysis revealed that they were characteristically psammitic and were predominantly of medium to fine grained
sand (>73%), less of silt (<15%) and clay (<10%). These results correlated with low levels of trace elements such as Pb (0.03 ± 0.02 mg kg−1), Cr (0.22 ± 0.12 mg kg−1), Cd (0.05 ± 0.03 mg kg−1), Cu (0.04 ± 0.02 mg kg−1) and Mn (0.23 ± 0.22 mg kg−1) in the sediment samples. This observation is consistent with the scarcity of clayey materials known to be good scavengers
for metallic and organic contaminants. Sediments indicated enhanced concentration of Fe, Ni and V, while other metal levels
were relatively low. The concentrations of all the metals except Pb in surface water were within the permissible levels, suggesting
that the petroleum contaminants had minimal effect on the state of pollution by trace metals in Iko River. Notably, the pollutant
concentrations in the sediments were markedly higher than the corresponding concentrations in surface water and T. fuscatus tissues, and decreased with distance from point sources of pollution. 相似文献
16.
Eichhornia crassipes was tested for its ability to bioconcentrate 8 toxic metals (Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) commonly found in wastewater
from industries. Young plants of equal size were grown hydroponically and amended with 0, 0.1, 0.3, 0.5, 1.0, 3.0, and 5.0
mM of each heavy metal individually for 21 days. The test plant had the lowest and the highest tolerance indices for Hg and
Zn, respectively. A significant (P ≤ .05) reduction in biomass production was observed in metal treated plants compared with the control. All strace elements
accumulated to higher concentrations in roots than in shoots. Trace element concentrations in tissues and the bioconcentration
factors (BCF) were proportional to the initial concentration of individual metal in the growth medium and the duration of
exposure. From a phytoremediation perspective, E. crassipes is a promising plant species for remediation of natural water bodies and/or wastewater polluted with low levels of Zn, Cr,
Cu, Cd, Pb, Ag and Ni. 相似文献
17.
Md. Saiful Islam Md. Kawser Ahmed Md. Habibullah-Al-Mamun Mohammad Raknuzzaman Mir Mohammad Ali Dennis Wayne Eaton 《The Environmentalist》2016,36(3):253-265
Contamination of heavy metals in fish and vegetables is regarded as a major crisis globally, with a large share in many developing countries. In Bogra District of Bangladesh, concentrations of six heavy metals, i.e., chromium (Cr), nickel (Ni), copper (Cu), arsenic (As), cadmium (Cd) and lead (Pb), were evaluated in the most consumed vegetables and fish species. The sampling was conducted during February–March 2012 and August–September 2013. The levels of metals varied between different fish and vegetable species. Elevated concentrations of As, Cd and Pb were observed in vegetable species (Solanum tuberosum, Allium cepa and Daucus carota), and fish species (Anabas testudineus and Heteropneustes fossilis) were higher than the FAO/WHO permissible limits, indicating these three metals might pose risk from the consumption of these vegetable and fish species. The higher concentration of heavy metals in these vegetable species might be due to the higher uptake from soil and sediment ingestion behavior in fish species. Multivariate principal component analysis (PCA) showed significant anthropogenic contributions of Cr, Ni, Cu and Pb in samples as the PCA axis scores were correlated with scores of anthropogenic activities. Target hazard quotients showed that the intakes of Cu, As and Pb through vegetables and fish were higher than the recommended health standards, indicated non-carcinogenic risk. Therefore, intakes of these elements via fish and vegetables for Bangladeshi people are a matter of concern. 相似文献
18.
19.
The optimized BCR sequential extraction procedure was applied to nine roadside soil samples for the determination of Cd, Cr,
Pb and Ni. The extractable metals were isolated into three operationally defined fractions viz: acid extractable, reducible
and oxidizable. The residue was treated with aqua regia solution. Metal analysis was done using flame atomic absorption spectrophotometry
with air–acetylene flame. Results obtained showed the concentrations of the metals as relative abundance in the mobile phases
of the samples (based on the sum of the first three fractions) are in the following order: Cd(91.9) > Pb(82.8) > Ni(49.5) > Cr(39.0).
The most non-mobilizable metals were Cr and Ni which are generally lithogenic, associated with the silicate matrix, and the
order is as follows: Cr(61.0) > Ni(50.5) > Pb(17.2) > Cd(8.1). The recovery of all the metals expressed as the ratio of total
metal concentration to fractional sum of the optimized BCR sequential extraction procedure was of the order: Cr(95.6) > Pb(95.0) > Ni(94.8) > Cd(92.4). 相似文献
20.
Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain 总被引:17,自引:0,他引:17
Rodríguez L Ruiz E Alonso-Azcárate J Rincón J 《Journal of environmental management》2009,90(2):1106-1116
Soil pollution by lead, zinc, cadmium and copper was characterized in the mine tailings and surrounding soils (arable and pasture lands) of an old Spanish Pb-Zn mine. Sixty soil samples were analyzed, determining the total metal concentration by acid digestion and the chemical fractionation of Pb and Zn by the modified BCR sequential extraction method. Samples belonging to mine waste areas showed the highest values, with mean concentrations of 28,453.50 mg kg(-1) for Pb, 7000.44 mg kg(-1) for Zn, 20.57 mg kg(-1) for Cd and 308.48 mg kg(-1) for Cu. High concentrations of Pb, Zn and Cd were found in many of the samples taken from surrounding arable and pasture lands, indicating a certain extent of spreading of heavy metal pollution. Acidic drainage and wind transport of dust were proposed as the main effects causing the dispersion of pollution. Sequential extraction showed that most of the Pb was associated with non-residual fractions, mainly in reducible form, in all the collected samples. Zn appeared mainly associated with the acid-extractable form in mine tailing samples, while the residual form was the predominant one in samples belonging to surrounding areas. Comparison of our results with several criteria reported in the literature for risk assessment in soils polluted by heavy metals showed the need to treat the mine tailings dumped in the mine area. 相似文献