Monitoring of Cr, Cu, Pb, V and Zn in polluted soils by laser induced breakdown spectroscopy (LIBS)

Laser Induced Breakdown Spectroscopy (LIBS) is a fast and multi-elemental analytical technique particularly suitable for the qualitative and quantitative analysis of heavy metals in solid samples, including environmental ones. Although LIBS is often recognised in the literature as a well-established analytical technique, results about quantitative analysis of elements in chemically complex matrices such as soils are quite contrasting. In this work, soil samples of various origins have been analyzed by LIBS and data compared to those obtained by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The emission intensities of one selected line for each of the five analytes (i.e., Cr, Cu, Pb, V, and Zn) were normalized to the background signal, and plotted as a function of the concentration values previously determined by ICP-OES. Data showed a good linearity for all calibration lines drawn, and the correlation between ICP-OES and LIBS was confirmed by the satisfactory agreement obtained between the corresponding values. Consequently, LIBS method can be used at least for metal monitoring in soils. In this respect, a simple method for the estimation of the soil pollution degree by heavy metals, based on the determination of an anthropogenic index, was proposed and determined for Cr and Zn.     

Accumulation of heavy metals in leaf vegetables from agricultural soils and associated potential health risks in the Pearl River Delta,South China

This study investigated the extent of heavy metal accumulation in leaf vegetables and associated potential health risks in agricultural areas of the Pearl River Delta (PRD), South China. Total concentrations of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr) and arsenic (As) were determined in 92 pairs of soil and leaf vegetable (flowering Chinese cabbage, lettuce, pakchoi, Chinese cabbage, loose-leaf lettuce, and Chinese leaf mustard) samples collected from seven agricultural areas (cities). The bioconcentration factors (BCF) of heavy metals from soil to vegetables were estimated, and the potential health risks of heavy metal exposure to the PRD residents through consumption of local leaf vegetables were assessed. Results showed that among the six leaf vegetables, pakchoi had the lowest capacity for heavy metal enrichment, whereas among the five heavy metals, Cd had the highest capacity for transferring from soil into vegetables, with BCF values 30-fold those of Hg and 50-fold those of Cr, Pb and As. Sewage irrigation and fertilization were likely the main sources of heavy metals accumulated in leaf vegetables grown in agricultural areas of the PRD region. Different from previous findings, soil pH had no clear effect on metal accumulation in leaf vegetables. Despite a certain degree of metal enrichment from soil to leaf vegetables, the PRD residents were not exposed to significant health risks associated with consumption of local leaf vegetables. Nevertheless, more attention should be paid to children due to their sensitivity to metal pollutants.     

Accumulation of heavy metals in dietary vegetables and cultivated soil horizon in organic farming system in relation to atmospheric deposition in a seasonally dry tropical region of India

Increasing consciousness about future sustainable agriculture and hazard free food production has lead organic farming to be a globally emerging alternative farm practice. We investigated the accumulation of air-borne heavy metals in edible parts of vegetables and in cultivated soil horizon in organic farming system in a low rain fall tropical region of India. The factorial design of whole experiment consisted of six vegetable crops (tomato, egg plant, spinach, amaranthus, carrot and radish) x two treatments (organic farming in open field and organic farming in glasshouse (OFG)) x seven independent harvest of each crop. The results indicated that except for Pb, atmospheric deposition of heavy metals increased consistently on time scale. Concentrations of heavy metals in cultivated soil horizon and in edible parts of open field grown vegetables increased over time and were significantly higher than those recorded in OFG plots. Increased contents of heavy metals in open field altered soil porosity, bulk density, water holding capacity, microbial biomass carbon, substrate-induced respiration, alkaline phosphatase and fluorescein diacetate hydrolytic activities. Vegetable concentrations of heavy metal appeared in the order Zn > Pb > Cu > Ni > Cd and were maximum in leaves (spinach and amaranths) followed by fruits (tomato and egg plant) and minimum in roots (carrot and radish). Multiple regression analysis indicated that the major contribution of most heavy metals to vegetable leaves was from atmosphere. For roots however, soil appeared to be equally important. The study suggests that if the present trend of atmospheric deposition is continued, it will lead to a destabilizing effect on this sustainable agricultural practice and will increase the dietary intake of toxic metals.     

贵州农业非点源污染土壤重金属含量特征及区域差异性研究

贵州农用地土壤在长期的耕作过程中,承载大量的重金属污染物,影响土壤质量。采集了贵州东部、南部、中部、北部主要农业非点源重金属污染区土壤样品进行检测。结果表明,贵州农业非点源重金属污染物主要是Hg、Pb,贵州省农业非点源污染土壤中重金属累积污染程度Hg＞Pb＞Cd＞As＞Cr。各地区污染物种类和程度不同,重金属As污染为中部地区较高,农业土壤Hg、Pb污染主要集中在中部和东部地区,Cd污染主要发生在南部区域。     

Spatial Characterization and Prioritization of Heavy Metal Contaminated Soil-Water Resources in Peri-Urban Areas of National Capital Territory (NCT), Delhi

Due to rapid industrialization and urbanization during last two decades, contamination of soils by heavy metals is on an increase globally. Lands under peri-urban agriculture are the worst affected. In NCT, Delhi about 14.4% of land area is chemically degraded. In order to take care of this problem, recently the Supreme Court of India ordered to shift various non-confirming (about 39,000 units) industries to regions outside NCT, Delhi. However in spite of this, there have been several reports and parliamentary debates on the phyto-toxicity and extensive accumulation of heavy metals in the region. Literature review revealed that the basis of these debates is a few studies on some point locations in/around Delhi. It was further observed that information on the distribution and extent of heavy metal pollution problem in the region was completely missing. The present study was thus basically aimed at assessing the spatial distribution/extent and type of heavy metal pollution in the study area, for enabling future designing of appropriate site-specific management measures by the decision makers.For this, detailed spatial information on bio-available heavy metal concentrations in the soils and surface/sub-surface waters of NCT (Delhi) was generated through actual soil/water surveys, standard laboratory methods and GIS techniques. The study showed that concentration of all micronutrients (viz. Zn: 0.05–0.18 ppm; Cu: in traces; Fe: 0–0.5 ppm; and Mn: 0–1.2 ppm) and most heavy metals (viz. Ni: 0–0.7 ppm; Pb: 0–0.15 ppm and Cd: in traces) in the surface/sub-surface irrigation waters were well within permissible limits. However Cr concentrations in irrigation waters of Alipur and Shahdara blocks were far above their maximum permissible limit of 1 ppm. It was further observed that Ni and Cr concentrations in the drinking waters of almost entire test area were far above maximum permissible levels of 0.02 and 0.01 ppm, respectively. Bio-available concentrations of several heavy metals (viz. Pb: 0.1–2 ppm; Cd: traces; Ni: 0.05–2 ppm and Cr: 0–0.4 ppm) in the study area soils were also observed to be well within the maximum permissible limits. However there were point Cu contaminations (5–10 ppm) in the sewage-sludge amended soils of vegetable growing areas near south Shahdara block. This was attributed to increased Cu availability due to oxidized acidic conditions generated by over-irrigation of agricultural lands. Available Mn concentrations in Kanjhawala, western Najafgarh and Alipur soils were also observed to be above maximum permissible limit of 10 ppm. This was observed to be mainly due to the geology (i.e. presence of Mn rich sedimentary rocks) and prevalence of reduced acidic conditions, due to paddy cultivation, in these areas. It was further observed that there is acute zinc (Zn) deficiency (< 0.6 ppm) in paddy growing soils of north Kanjhawala, Alipur and some parts of Najafgarh and Shahdara blocks due to extensive leaching of available Zn fractions to lower soil horizons. Similar available Zn deficiencies in high pH (8.5) soils of areas around Bamnoli village in E-Najafgarh block were also observed.     

Distribution of heavy metals in agricultural soils near a petrochemical complex in Guangzhou, China

The aim of the study was to investigate influence of an industrialized environment on the accumulation of heavy metals in agricultural soils. Seventy soil samples collected from surface layers (0-20 cm) and horizons of five selected pedons in the vicinity area of petrochemical complex in Guangzhou, China were analyzed for Zn, Cu, Pb, Cd, Hg and As concentrations, the horizontal and vertical variation of these metals were studied and geographic information system (GIS)-based mapping techniques were applied to generate spatial distribution maps. The mean concentrations of these heavy metals in the topsoils did not exceed the maximum allowable concentrations in agricultural soil of China with the exception of Hg. Significant differences between land-use types showed that Cu, Pb, Cd, Hg and As concentrations in topsoils were strongly influenced by agricultural practices and soil management. Within a radius of 1,300 m there were no marked decreasing trends for these element concentrations (except for Zn) with the increase of distance from the complex boundary, which reflected little influence of petroleum air emission on soil heavy metal accumulation. Concentrations of Zn, Cu, Pb, Cd, Hg and As in the five pedons, particularly in cultivated vegetable field and orchard, decreased with soil depth, indicating these elements mainly originated from anthropogenic sources. GIS mapping was a useful tool for evaluating spatial variability of heavy metals in the affected soil. The spatial distribution maps allowed the identification of hot-spot areas with high metal concentration. Effective measures should be taken to avoid or minimize heavy metal further contamination of soils and to remediate the contaminated areas in order to prevent pollutants affecting human health through agricultural products.     

Heavy metal uptake and its effect on macronutrients, chlorophyll, protein, and peroxidase activity of Paspalum distichum grown on sludge-dosed soils

This study assessed the heavy metal (Cr, Mn, Ni, Cu, Zn, and Pb) uptake and its effect on biochemical parameters in Paspalum distichum, a wetland plant. Sludge collected from Bhalswa waste dump, New Delhi, was used as heavy metal source and dosed in different proportions viz. 20%, 40%, 60%, and 80% to the garden soil. The plants accumulated metals mostly in belowground organs. The metal accumulation followed the order: Cr>Mn>Cu>Zn>Ni>Pb. The range of heavy metal concentration in tissue of belowground organs after 180 days of growth was 1,778.65–4,288.01 ppm Cr, 828.11–1,360 ppm Mn, 236.52–330.07 ppm Ni, 155.79–282.35 ppm Cu, 27.05–91.16 ppm Zn, and 27.09–50.87 ppm Pb. The biochemical parameters viz. chlorophyll and protein contents and peroxidase (POD) activity exhibited no considerable adverse effect indicating the plants’ tolerance towards heavy metals. The high POD activity and synthesis of new protein bands at high sludge-dosed plants were also in support of this fact.     

乌鲁木齐市米东污灌区农田土壤重金属污染评价

对米东污灌区农田土壤重金属含量进行监测分析,利用不同的评价方法和标准对土壤重金属的环境质量进行评价。结果表明:米东污灌区农田土壤重金属含量分别为Cd(0.12±0.06)mg/kg,Cu(40.43±5.30)mg/kg,Zn(78.38±11.04)mg/kg,Pb(11.66±11.79)mg/kg,Ni(20.24±8.05)mg/kg,Cr(75.81±8.05)mg/kg。以国家土壤环境质量标准(二级)为标准评价,各元素的污染指数排序为Cu>Ni>Cr>Zn>Cd>Pb,综合污染指数为0.337,污染程度为安全。以食用农产品产地土壤环境质量要求为标准评价,各元素的污染指数排序为Cu>Ni>Cr>Zn>Cd>Pb,综合污染指数为0.343,污染程度为安全。表明米东污灌区农田土壤重金属含量尚能达到食用农产品产地土壤环境质量要求。Pb、Cu、Zn的平均含量超过乌鲁木齐市土壤背景值,这说明污灌区土壤重金属Pb、Cu、Zn近年来已有所累积,存在一定的污染风险。     

Roadside Rhododendron pulchrum leaves as bioindicators of heavy metal pollution in traffic areas of Okayama, Japan

The leaves of roadside Rhododendron pulchrum Sweet were examined as a bioindicator of traffic-related heavy metal pollution in Okayama. Total contents of heavy metals in roadside soil and the R. pulchrum leaves were determined. Results of correlation analyses showed significant correlations among Pb, Ni, and Zn contents of roadside soil and leaf samples. These results suggest that R. pulchrum is a useful bioindicator of heavy metal pollution in traffic areas. To identify traffic-related heavy metal pollution sources, traffic-related materials such as tires, asphalt pavement, and road paint were collected and analyzed. The results of analyses of our data show that Zn is emitted mainly from the abrasion of tires; Cr is emitted mainly from wear of the asphalt pavement. Furthermore, the respective lead isotope ratios in R. pulchrum leaves, soil, roadside dust, and traffic-related materials were measured using inductively coupled plasma mass spectrometry. The isotopic compositions of lead in R. pulchrum leaves were 207Pb/206Pb = 0.861-0.871 and 208Pb/206Pb = 2.093-2.127, which agrees well with ratios in automobile wheel balance weights, suggesting that lead-containing products associated with automobiles, such as wheel balance weights, contribute to traffic-related lead pollution.     

Effect of fertilizer application on soil heavy metal concentration

A large amount of chemicals is annually applied at the agricultural soils as fertilizers and pesticides. Such applications may result in the increase of heavy metals particularly Cd, Pb, and As. The objective of this study was to investigate the variability of chemical applications on Cd, Pb, and As concentrations of wheat-cultivated soils. Consequently, a study area was designed and was divided into four subareas (A, B, C, and D). The soil sampling was carried out in 40 points of cultivated durum wheat during the 2006–2007 periods. The samples were taken to the laboratory to measure their heavy metal concentration, soil texture, pH, electrical conductivity, cationic exchange capacity, organic matter, and carbonate contents. The result indicated that Cd, Pb, and As concentrations were increased in the cultivated soils due to fertilizer application. Although the statistical analysis indicates that these heavy metals increased significantly (P value < 0.05), the lead and arsenic concentrations were increased dramatically compared to Cd concentration. This can be related to overapplication of fertilizers as well as the pesticides that are used to replant plant pests, herbs, and rats.     

杭州地区农业土壤中重金属的分布特征及其环境意义

为了分析杭州地区农业土壤重金属的分布特征及其环境意义,通过现场采样和室内分析检测的方法,对杭州市各区县不同作物农业土壤表层土中的Hg、As、Cu、Pb、Cr、Cd 6种重金属元素进行检测,并对其分布特征进行了分析。结果表明,杭州地区农业土壤中除As外,其他5种重金属的平均含量均低于且接近浙江省土壤背景值,个别采样点的重金属含量超过了土壤环境质量国家二级标准。总体上,杭州地区农业土壤处于安全水平。通过重金属的区域分布特征分析表明,余杭区和富阳市农业土壤中重金属平均含量普遍高于其他区域。萧山区和建德市部分农业土壤则存在Cu和Hg含量较高的情况,而淳安县农业土壤中重金属含量差异较大,土壤中出现了As、Cr和Cd含量最大值。不同作物的农业土壤重金属含量存在一定的差异,但不明显。水稻田和蔬菜地的土壤中,重金属含量较其他作物种植类型的土壤中含量高;叶菜类(蔬菜、茶叶)作物土壤中的Cd含量要比根茎类(水稻)、茄果类(水果)及其他作物种植类型的土壤中的含量低。目前杭州地区土壤中6种重金属含量均对作物的直接危害不大,但由于萧山区个别采样点Cu含量严重超标,淳安县土壤中Cd受外源性来源影响也已较明显,需要相关部门加大监管力度,防止污染事件发生。同时,为防止农业土壤中重金属含量进一步升高,需要加大大气降尘监测与治理、废气污染监管与控制治理。     

云南个旧土壤农作物重金属污染特征及潜在风险

在实地调查和实验室分析的基础上,对云南省个旧市大屯镇土壤农作物重金属污染状况进行了评价。结果显示:个旧市大屯镇调查区域土壤中Pb、Zn、Cd、As平均质量分数分别为943. 5、454. 8、3. 4、302. 1 mg/kg,分别为国家农用地土壤污染风险管控标准筛选值的7. 8、1. 8、11. 2、10. 1倍,土壤污染严重。土壤Cd的生态危害最强,As、Pb的生态危害次之,Zn表现为轻微的生态危害。从潜在生态危险指数来看,所采集的土壤样品皆表现为极强的生态危害。所采集农作物与食品安全国家标准对比,结果显示,大米中Pb、Cd和As的超标率分别为35%、55%和100%;玉米中Pb、Cd和As的超标率分别为13%、0%和0%;小苦菜Pb、Cd和As的超标率分别为100%、60%、100%;小米菜中Pb、Cd和As的超标率均为100%,蔬菜类的重金属超标情况相对于谷物类较为严重。研究区域土壤样品总量Pb、Zn与有效态皆呈极显著正相关关系,总量Cd与有效态呈弱正相关关系,总量As与有效态表现为相关性不显著。     

燃煤电厂周边大气重金属污染特征及来源解析

为探究燃煤电厂周边大气环境中重金属的污染特征与来源,对广东某山区燃煤电厂周边地区环境和污染源的重金属进行测定,分析其污染特征,采用因子分析法和Pb同位素示踪法对环境中的重金属进行来源解析。结果表明,研究区域室内积尘中重金属浓度水平明显高于土壤重金属,污染空间分布与当地气象条件相关。环境空气TSP中重金属主要来自2个污染源,Cd、Pb、As主要来自电厂燃煤,Ca、Mn、Al、Mg主要来自土壤扬尘。TSP、降尘、积尘样品所含的Pb均与电厂采集的煤、炉渣、粉煤灰样品所含的Pb具有同源性,与其他污染源同源性不明显,说明研究区域大气中Pb污染主要来自电厂燃烧所排放的烟尘,其他污染源影响不大。     

Occurrence of heavy metals in fish: a study for impact assessment in industry prone aquatic environment around Kolkata in India

A study was conducted during November 2005-October 2006 for determining the heavy metal contamination in surface water and sediments and giving prime thrust to determine the heavy metal concentrations fish samples collected from various points of the river Ganga at different time interval. Fish samples (viz., Channa marulius and Aorichthys seengala) were analyzed for heavy metals using standard laboratory procedures by AAS method. In impact points the annual average values for Cu, Cr, Cd, Pb and Zn were 0.15, 0.04, 0.03, 0.02 and 0.29 ppm, respectively. The concentrations of heavy metals in the riverine water collected from middle point had the order Zn > Cu > Cr > Cd > Pb. The data indicated that copper was maximally accumulated in the riverine sediments whereas least annual average concentration was obtained for lead. The trend of accumulation suggested deposition was maximum for zinc and minimum for cadmium in the muscles of both fish species. Only zinc has shown some significant seasonal variation in relation to metal deposition in fish muscles (minimum in monsoon and maximum in summer). The heavy metal contamination to fish may be due to indiscriminate discharge of polluted and untreated sewage sludge to the river. The heavy metal contents in fish at some places are alarming.     

物元分析法在土壤重金属污染评价中的应用

针对实际中的土壤重金属污染状况是渐变的、模糊的,采用物元分析模型法通过建立物元矩阵,引用毒性响应系数对模型中权重的计算方法进行改进,并将改进的物元分析模型对广西环江某受铅锌矿影响的土壤重金属污染状况进行评价分析。结果表明,该区域土壤受重金属污染严重,尤其受Pb、Cd的影响更为严重,此评价结果符合当地的实际情况,同时与潜在生态危害指数评价结果一致,说明物元分析法在土壤重金属污染评价中的应用是合理的,其评价结果具有可靠性。     

某钢丝绳典型产业区土壤重金属含量现状调查

以钢丝绳产业集聚区内的土壤为研究对象,采集和分析产业区中心河两边淹水环境下的水稻田、少用受污染河水灌溉的棉花田及不用受污染河水灌溉的蔬菜地样本,结果表明,产业区内土壤中铅和锌的含量明显高于产业区外。产业区内除水稻田土壤中铅的质量比超过评价参比值外,其他灌溉方式下土壤中铅和锌的质量比均未超过《土壤环境质量标准》（GB 15618-1995）中的二级标准（pH值＞7）。统计分析表明,土壤中的重金属含量与废水灌溉方式有关,该产业区内土壤外源重金属来自钢丝绳产业的可能性很大。在不同的灌溉方式下,土壤剖面样品中的重金属含量随着土壤深度增加呈现降低的趋势,2010年和2011年的测定结果无显著差异。     

Monitoring of toxic elements present in sludge of industrial waste using CF-LIBS

Industrial waste is one of the main causes of environmental pollution. Laser-induced breakdown spectroscopy (LIBS) was applied to detect the toxic metals in the sludge of industrial waste water. Sludge on filter paper was obtained after filtering the collected waste water samples from different sections of a water treatment plant situated in an industrial area of Kanpur City. The LIBS spectra of the sludge samples were recorded in the spectral range of 200 to 500 nm by focusing the laser light on sludge. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique was used for the quantitative measurement of toxic elements such as Cr and Pb present in the sample. We also used the traditional calibration curve approach to quantify these elements. The results obtained from CF-LIBS are in good agreement with the results from the calibration curve approach. Thus, our results demonstrate that CF-LIBS is an appropriate technique for quantitative analysis where reference/standard samples are not available to make the calibration curve. The results of the present experiment are alarming to the people living nearby areas of industrial activities, as the concentrations of toxic elements are quite high compared to the admissible limits of these substances.     

Spatial distribution of heavy metals content in soils of Amik Plain (Hatay, Turkey)

The purpose of the study was to investigate the total and bio-available contents of heavy metals (Cd, Co, Ni, and Pb) and to determine their spatial variability in the Amik Plain, Turkey. Samples of surface and subsurface soil were collected at 132 sites in the research area. All of the total metal concentrations except Ni were considerably lower than their maximum allowable concentrations. Mean available Pb concentrations at both depths were above the permissible limits, while the other metal concentrations were within the proposed limits. Semivariograms of all the total metal contents, pH, and available Ni and Pb content were best fitted to spherical models, while available Cd and Co contents were best fitted to exponential models. Block kriging was used to interpolate values at unmeasured locations, generating maps of spatial variation for each heavy metal and pH.     

EFFECTS OF AN OIL SPILL ON SOIL PHYSICO-CHEMICAL PROPERTIES OF A SPILL SITE IN A TYPIC PALEUDULT OF MIDWESTERN NIGERIA

Physico-chemical analysis of soil samples at an oil spill sitein a Typic Paleudult of midwestern Nigeria showed that thetotal hydrocarbon content of top soil layers ranged from 0.6to 12.6 ppm in the heavy impact zone and the oil hadpenetrated to a depth of 9.2 m. Hydrocarbon concentration inthe medium impact zone ranged from 0.36 ppm while hydrocarbonswere not detected in 80% of samples from the unimpactedreference zone. Measurement of heavy metal concentrations inthe soil revealed a significant build-up (p< 0.05) of lead,iron and zinc in the heavy impact zone. Other parametersincluding electrical conductivity, exchangeable cations,available phosphorus and total nitrogen in impacted soils werecomparatively low while the total organic carbon was high,compared with the reference site. Textural class of soil fromthe different depths showed a predominantly brown sand at thetopsoil, loamy sand and grey fine sand at medium depths andred sandy clay at greater depths.     

Levels of some toxic elements and frequency of bacterial heavy metal resistance in sediment and sea water

The Golden Horn Estuary located in the Istanbul region of Turkey has been thought to be a heavily polluted area since the 1950s: the concentration of the elements, which include heavy metals such as Cu2+, Mn2+, Ni2+, Zn2+, Pb2+, Cd2+, and Fe2+, was therefore investigated in sediment and water samples of the area. The resistance of Enterobacteriaceae members to some heavy metal salts was investigated to determine levels of metal-resistant bacteria in the Golden Horn Estuary after the environmental restoration project in 1998. The sediment samples were collected with an Ekman-Grab in the period from November 2002 to February 2004 from depths of 4-15 m and analyzed by means of an atomic absorption spectrophotometer. Analyses of average heavy metals of sediment samples yielded the following results: 131.5 ppm Cu, 405.5 ppm Mn, 46.5 ppm Ni, 191.2 ppm Zn, 81.5 ppm Pb and 27668 ppm Fe. As with water, Ni concentrations in sediment were found lower than that in limit values. Frequency of heavy metals resistance to Cu, Zn, Fe, Ni, Mn, Pb and Cd was detected as an average of 65.0%, 64.4%, 62.5%, 38.4%, 37.3%, 36.2% and 28.4%, respectively in a total of 192 strains isolated from sediment samples. It was observed that there was no statistically significant difference among the results of analyses with respect to sampling dates. Despite the environmental restoration project in 1998, our study results showed that heavy metal levels were still high in the sediment and this situation induced the tolerance of bacteria to some heavy metals.