Effects of Municipal Sewage Sludge Doses on the Chlorophyll Contents and Heavy Metal Concentration of Sugar Beet (Beta vulgaris var. saccharifera)

The present study was conducted to assess the suitability of sewage sludge amendment (SSA) in soil for Beta vulgaris var. saccharifera (sugar beet) by evaluating the heavy metal accumulation and physiological responses of plants grown at a 10%, 25%, and 50% sewage sludge amendment rate. The sewage sludge amendment was modified by the physicochemical properties of soil, thus increasing the availability of heavy metals in the soil and consequently increasing accumulation in plant parts. Cd, Pb, Ni, and Cu concentrations in roots were significantly higher in plants grown at 25% as compared to 50% SSA; however, Cr and Zn concentration was higher at 50% than 25% SSA. The concentrations of heavy metal showed a trend of Zn > Ni > Cu > Cr > Pb > Cd in roots and Zn > Cu > Ni > Cr > Pb > Cd in leaves. The only instance in which the chlorophyll content did not increase after the sewage sludge treatments was 50%. There were approximately 1.12-fold differences between the control and 50% sewage sludge application for chlorophyll content. The sewage sludge amendment led to a significant increase in Pb, Cr, Cd, Cu, Zn, and Ni concentrations of the soil. The heavy metal accumulation in the soil after the treatments did not exceed the limits for the land application of sewage sludge recommended by the US Environmental Protection Agency (US EPA). The increased concentration of heavy metals in the soil due to the sewage sludge amendment led to increases in heavy metal uptake and the leaf and root concentrations of Ni, Zn, Cd, Cu, Cr, Pb, and Zn in plants as compared to those grown on unamended soil. More accumulation occurred in roots and leaves than in shoots for most of the heavy metals. The concentrations of Cd, Cr, and Pb were more than the permissible limits of national standards in the edible portion of sugar beet grown on different sewage sludge amendment ratios. The study concludes that the sewage sludge amendment in the soil for growing sugar beet may not be a good option due to risk of contamination of Cr, Pb, and Cd.     

EFFECTS OF INOCULATION WITH ARBUSCULAR MYCORRHIZAL FUNGI ON MAIZE GROWN IN MULTI-METAL CONTAMINATED SOILS

Pot culture experiments were established to determine the effects of colonization by arbuscular mycorrhizal fungi (AMF) (Glomus mosseae and G. sp) on maize (Zea mays L.) grown in Pb, Zn, and Cd complex contaminated soils. AMF and non-AMF inoculated maize were grown in sterilized substrates and subjected to different soil heavy metal (Pb, Zn, Cd) concentrations. The root and shoot biomasses of inoculated maize were significantly higher than those of non-inoculated maize. Pb, Zn, and Cd concentrations in roots were significantly higher than those in shoots in both the inoculated and non-inoculated maize, indicating the heavy metals mostly accumulated in the roots of maize. The translocation rates of Pb, Zn, and Cd from roots to shoots were not significantly difference between inoculated and non-inoculated maize. However, at high soil heavy metal concentrations, Pb, Zn, and Cd in the shoots and Pb in the roots of inoculated maize were significantly reduced by about 50% compared to the non-inoculated maize. These results indicated that AMF could promote maize growth and decrease the uptake of these heavy metals at higher soil concentrations, thus protecting their hosts from the toxicity of heavy metals in Pb, Zn, and Cd complex contaminated soils.     

The use of indigenous plant species and calcium phosphate for the stabilization of highly metal-polluted sites in southern Poland

Highly metal-polluted (Pb, Cd, Zn) soil from a non-ferrous mine and smelter site in southern Poland, further referred to as Waryski soil, was used to test indigenous plant species for stabilization effectiveness of heavy metals in soils. Results of pilot investigations with commercially available cultivars of plant species showed that these cultivars could not grow on this highly polluted soil even with the application of soil amendments to stabilize the heavy metals. Based on these results, mesocosm and field experiments with an indigenous, metal-tolerant ecotype of Deschampsia cespitosa from the Waryñski site were carried out. The mesocosm experiment showed that applications of calcium phosphate (3.8% w/w) as a heavy metal-stabilizing amendment decreased Cd and Zn concentrations 2 and 3-fold respectively in leachates, whereas lead content was not significantly changed. This decrease in the concentration of heavy metals in leachates was correlated with a lower accumulation of Pb, Cd and Zn in the roots and shoots of D. cespitosa, ecotype Waryñski. In the field experiment, lower accumulations of Cd in roots and shoots and Zn in shoots in the amendment added plot were observed during the second year of investigations. In the first growing season, D. cespitosa plant cover in the amendment enriched mesocosms ranged from 95 to 100%, compared to 10% in mesocosms without calcium phosphate. In the second year of the experiment, in non-amendment enriched mesocosms D. cespitosa was substituted with Cardaminopsis arenosa(95% cover). C. arenosa is an undesirable species for phytostabilization, as it accumulates high amounts of zinc and cadmium in its shoots, even thought it provided better growth cover in not amended soils. However, in amended mesocosms, soil surface cover by D. cespitosa was still very high (90%). Similar results were obtained in field experiments. Addition of calcium phosphate to the soil also resulted in excellent D. cespitosa root system development when compared to soils without amendment. In amended mesocosms, high plant cover and root system development significantly decreased the volume of leachates and improved water retention. These results indicate that the use of D. cespitosa, ecotype Waryski in combination with calcium phosphate as a heavy metals immobilizing agent is sufficient to restore a dense vegetative cover to highly heavy metal-polluted soil.     

Effect of Compost and Biochar on Heavy Metals Phytostabilization by the Halophytic Plant Old Man Saltbush [Atriplex Nummularia Lindl]

Remediation of soils is vital to mitigate the negative effects of heavy metals in ecosystems. There is little information available about the metals’ phytostabilization potential of old man saltbush plants [Atriplex nummularia]. A pot experiment in a randomized complete block design was conducted to study the accumulation of heavy metals by old man saltbush plants, as affected by the application of compost and biochar. The cultivation of A. nummularia is an effective tool in immobilizing metals in the contaminated soils. The cultivation of metal-contaminated soil with A. nummularia reduced the availability of Zn, Cu, Cd, and Pb by 20%, 4%, 21%, and 28%, respectively, in comparison to the non-cultivated soil. Zn, Cu, Cd, and Pb concentrations in the aboveground parts of old man saltbush plants were 70–100, 50–80, 4–5, and 50–90 mg/kg of dry biomass. The higher Zn, Cu, Cd, and Pb concentrations were accumulated in the roots, and the lower concentrations were transferred to the shoots of old man saltbush plants. Compost reduced the concentration of Zn, Cu, Cd, and Pb in the shoots by 10%, 19%, 20%, and 6%, respectively, compared to the control soil. Biochar reduced the concentrations of Zn, Cu, and Pb in the shoots by 30%, 38%, and 44%, respectively, compared to the control. Compost had a lower effect in reducing the metals uptake as biochar. Biochar reduced the uptake of Zn, Cu, and Pb in the shoots of the tested plant by 22%, 23%, and 41%, respectively, in comparison to compost. Based on the obtained results, old man saltbush has good characteristics to be a promising candidate for phytostabilization strategies of metal-contaminated soils. Moreover, biochar is a good tool to enhance metals’ phytostablization.     

Risk Element (As,Cd, Cu,Pb, and Zn) Contamination of Soils and Edible Vegetables in the Vicinity of Guixi Smelter,South China

Risk element (As, Cd, Cu, Pb, and Zn) contamination in soils and in two edible vegetables (Solanum melongena L. and Capsicum annum L.) was investigated in the vicinity of Guixi Smelter, South China. Soil As concentrations averaged 23.9 mg/kg. Sites near the smelter tailings recorded the highest levels of As and heavy metals in soils. The concentration order of heavy metals in soils was Cd < Pb < Zn < Cu. Cu and Cd in soils were abundant in the exchangeable and bound to carbonate fraction, while Pb and Zn were in the residual fraction, limiting their potential toxicity as pollutants. The proportions of the metals in the mobile fraction followed the order Pb < Zn < Cu < Cd. In Solanum melongena L. and Capsicum annum L., Zn concentration was the highest, followed by Cu, Cd, and Pb, different from that in soils and in the mobile fraction. Concentrations of heavy metals in the labile fractions in soils and in vegetables presented significant correlation (p < 0.05). Both of the two vegetables are not the Cu and Zn accumulators. As for Cd and As, Capsicum annum L. poses a higher risk to animal and human health than Solanum melongena L., with soil-plant transfer coefficients more than three. Root-stem is the main barrier for most of the heavy metals and As in the two vegetables, resulting in higher metal concentrations in roots relative to other plant tissues. The low stem-fruit transfer coefficients for Zn in Solanum melongena L. and for Pb in Capsicum annum L. suggested that very few of them could reach the fruits.     

菰和菖蒲对重金属的胁迫反应及其富集能力

通过盆栽实验研究了Cu—Zn—Ph-Cd复合污染条件下,菰和菖蒲的生长状况、生理特性及吸收和富集重金属的能力。结果表明,高浓度污染下菰和菖蒲不能存活;低、中浓度中菖蒲的生长受到抑制,菰各生长指标与对照相比差异不显著,表明菰对低、中浓度重金属的耐性强于菖蒲。随着污染浓度的增加,菰和菖蒲叶片叶绿索含量显著降低;菰叶绿素a／b值略有降低,菖蒲叶绿素a／b值显著降低;菰和菖蒲叶片脯氨酸含量、相对电导率显著升高,超氧化物歧化酶（SOD）、过氧化物酶（POD）活性在低浓度时升高,中浓度时降低。菰体内重金属含量为Zn〉Cu〉Pb〉Cd,菖蒲体内的含量为Cu〉Zn〉Pb〉Cd,且二者体内的重金属含量都随着污染浓度的增加而升高。菰和菖蒲对Cd的富集系数较大,地上部分（茎与叶）和地下部分（根与根状茎）均大于1;对Pb的富集系数较小,地上部分和地下部分均小于1。菰和菖蒲地下部分重金属含量均高于地上部分含量,二者根系对4种重金属都有较强的滞留效应,平均滞留率均大于50％。各处理中菰对重金属的吸收量均高于菖蒲。综合分析菰和菖蒲的生长、生理及富集重金属的能力,菰比菖蒲更适用于低、中浓度重金属污染水体的生态修复。     

Spatial Distribution of Heavy Metals in Soil and Flora Associated with the Glass Industry in North Central India: Implications for Phytoremediation

The effect of the glass industry on soil metal characterization was assessed at five test sites at five successive distances in a semi-arid area. A comprehensive profile of Zn, Cd, Pb, Ni, Cu, and As levels in soils was obtained. The spatial distribution patterns of integrated contamination indices for these metals show a similar decreasing trend in distribution as we move further from the industrial cluster. There was significant correlation among individual heavy metal concentrations in the soil samples. Integrated contamination indices indicate that 64% of the sites were in the high contamination range and 28% were in the moderate contamination range. A statistically significant difference (P ≤ 0.001) was obtained for each metal on comparing mean metal content among soil samples. Phytoremedial potential of 12 native plant species was also evaluated. Individual elements displayed remarkably different patterns of accumulation in soils as well as plants. Plants established limited capabilities in mobilizing Zn, Pb, Ni, and Cu in the root zone. While Cd, Cu, As, Zn and Pb were predominantly partitioned in shoots, Ni was equally partitioned between shoots and roots. Interestingly, some plants showed a different partitioning trend at higher concentrations of different metals compared to lower concentrations. Potential species for phytoremediation include Calotropis procera (Milk weed), Chenopodium murale (Goosefoot),Poa annua (Annual bluegrass) and Datura stramonium (Thorn apple). None of the species showed phytoremedial potential for Ni and Cu.     

Accumulation and subcellular distribution of heavy metal in Paulownia fortunei cultivated in lead-zinc slag amended with peat

Abstract

The contamination of toxic heavy metals was a major issue of concern in the last century. A fast-growing metal-accumulating woody plant is a promising approach for the remediation of toxic heavy metal. In this study, the transportation of heavy metals (Pb, Zn, Cu, and Cd) in Paulownia fortunei cultivated in lead-zinc slag amended with different mass ratios of peat (CK: 0; T1: 10%; T2: 20%; T3: 30%) was investigated, as well as the subcellular distribution of Pb, Zn, Cu, and Cd in Paulownia fortunei. The results showed that the accumulation content of Pb, Zn, Cu, and Cd in Paulownia fortunei were increased with peat amendment, which was in the range of 4.216?～?6.853, 20.905?～?23.017, 1.898?～?2.572, and 0.530?～?0.616?mg/pot, respectivly. The experimental group with 30% dose of peat showed the best performance on the accumulation content of Pb, Zn, Cu, and Cd, with increase rates (compared to control) of 4.088, 10.573, 1.360, and 0.294?mg/pot, respectively. The bioconcentration, translocation and transfer quantity factor of Pb, Zn, Cu, and Cd were less than 1. Fixation of cell wall and compartmentalization of vacuolar appeared to play an important role in reducing the toxicity of Pb, Zn, Cu, and Cd.     

Impact of Compost on Metals Phytostabilization Potential of Two Halophytes Species

Phytostabilization of heavy metals in contaminated soils should be subject to two conditions, the first is the choice plant must be able to stabilize heavy metals in soil, the second is the plant material which produced from the phytostabilization process must be safe and useful to avoid overload on environmental system. A field experiment was conducted out to evaluate the phytostabilization potential of two halophytes species (Atriplex lentiformis and Atriplex undulata). Compost at rates of 0, 15 and 30 ton ha^?1 was used to examine its role in plant growth and heavy metals uptake. The high rate of compost (30 ton ha^?1) decreased zinc (Zn) concentrations in the leaves of A. lentiformis and A. undulata by 15.8 and 13.0%, while lead (Pb) in the leaves decreased by 37.6 and 35.2% respectively. Despite the extremely high total heavy metals concentrations in the studied soil, plants of Atriplex were able to grow and maintain shoots metals content below the toxic level and the produced plant materials had a high nutritive value compared to the conventional forage crops. Phosphorus (P) and chloride (Cl) in the roots of Atriplex plants play important function in heavy metals phytostabilization mechanism by the two halophytes plants.     

添加污泥对尾矿砂理化性质及香樟生理特性的影响

以香樟作为指示植物,选取黄岩、临海和路桥地区污水处理厂污泥,将污泥与尾矿砂按(污泥质量比例为0%对照、25%、50%和75%)配比进行栽培试验。测定添加污泥对尾矿砂理化性质以及香樟生理特性的影响。结果表明:随着污泥比例的增加,混合基质中的有机质、全氮、全磷明显增加,pH值明显降低,离子交换量明显减少,Cu和Cd总量明显增加,而Pb总量明显减少,Zn总量没有明显变化,Cu、Cd和Zn的DTPA提取量明显增加,而Pb的DTPA提取量明显减少。黄岩和临海污泥在25%和50%比例时,香樟叶和茎的生物量和叶绿素含量明显增加,而根的生物量没有明显变化,在75%比例时,生物量和叶绿素含量均明显减少;而添加路桥污泥使香樟叶、茎和根的生物量和叶绿素含量明显减少。丙二醛含量则与生物量和叶绿素含量呈现相反的变化特征。黄岩和临海污泥在25%和50%比例时,根和叶的Cu、Cd、Pb和Zn含量明显减少,在75%比例时,Cu、Cd和Zn含量则明显增加;而添加路桥污泥使叶和根的Cu、Cd和Zn含量明显增加,Pb含量明显减少。研究表明添加污泥提高了尾矿砂的养分含量,同时改变了其重金属组成,对污泥重金属含量和有机质组成的监控可以准确地预测污泥改良后尾矿砂对植物毒性的变化。     

Phytostabilization of polymetallic contaminated soil using Medicago sativa L. in combination with powdered marble: Sustainable rehabilitation

This study uses an ecotoxicology approach to evaluate the effectiveness of combining powdered marble as an amendment, with phytostabilization by Medicago sativa L. on the neutralization of acidic mine tailings, and the stabilization of heavy metals. The mine tailings were collected from an abandoned polymetallic mine in Southern Morocco, and mixed with powdered marble as the following proportions, 25%, 50%, and 75%. Laboratory immobilization/stabilization tests showed that the application of powdered marble in the treatments led to a significant increase in pH, and significant reductions of Cu, Zn (99%), Pb (98%), and Fe (45%). Greenhouse experiments showed that plant growth in all treatments was significantly (p ≤ 0.05) less than growth in agricultural soil. Plant growth significantly (p ≤ 0.05) decreased as the proportion of powdered marble increased. The concentration of metals in plant roots were significantly (p ≤ 0.05) higher than those of shoots. Combining immobilization by powdered marble with phytostabilization by M. sativa L. could represent a viable method of rehabilitating acidic polymetallic mine tailings.     

Factors affecting the distribution of cadmium,copper and lead and their effect upon yield and zinc content in bush beans (Phaseolus vulgaris L.)

Summary Concentrations of Cd, Pb and Cu in the roots, stems and leaves of bulgarian bush beans (Phaseolus vulgaris L.) were determined for plants grown in various soils of increasing levels of contamination of these metals. Most of each heavy metal absorbed by plants was retained in roots. Concentrations of Cd, Pb and Cu in roots increased in response to soil concentrations, whereas, in stems, only Cd and Pb concentrations increased and Cu concentration was relatively constant. It is thought that Cu transport to the stele was metabolically controlled, whereas Cd and Pb reached the stem by leakage across non suberised areas of the endodermis. Uptake of heavy metals was associated with a decrease in zinc content in plants and a decrease in yield. By regression analysis decrease in both zinc content and plant yield could be best related to Cd content in stems. Possible reasons for these effects are discussed.     

Heavy metal localisation in mycorrhizas ofEpipactis atrorubens (Hoffm.) Besser (Orchidaceae) from zinc mine tailings

Summary The metal distribution within mycorrhizal and nonmycorrhizal roots ofEpipactis atrorubens collected from zinc mine tailings and an area rich in heavy metal ores (both located in southern Poland) was investigated. The tailings, consisting of postflotation material, were characterised by high levels of toxic elements such as Zn, Pb, and Cd, while soil outside the tailings was also strongly enriched in heavy metals. Atomic absorption spectrometry and proton-induced X-ray emission analysis revealed that heavy metals were mostly accumulated within orchid roots. Elemental maps from proton-induced X-ray emission showed that plant root epidermis and fungal coils which had developed within cortical cells of roots collected from the zinc mine tailings were the main places of Zn and Pb accumulation, associated with increased concentrations of Fe, Cd, Ti, Mn, Si, Ca, and S. The mean content of Pb and Zn in the coils was 4 to 5 times higher than in the root epidermis. In mycorrhizal roots from the tailings a statistically significant decrease in Pb and Zn content towards the inside of the root was observed. The mean content of Pb in coils from roots of plants growing outside the tailings was about 1% of the concentration in root coils from the tailings. Coils selected from orchid roots originating from a site outside the tailings contained comparatively high concentrations of Zn, Cd, and Cu, which was probably due to the high content of these elements in the soil. The results presented suggest a biofiltering effect against heavy metals by orchid mycorrhizal fungi.     

Aquatic and terrestrial plant species with potential to remove heavy metals from storm-water

Remediation of storm-water polluted with heavy metals should be possible in percolation systems, ponds, or wetlands. The aim of this work was to find plant species for such systems that are efficient in the uptake of Zn, Cu, Cd, and Pb. Plants were collected from percolation and wetland areas and analyzed for heavy metal concentrations. Results showed that submersed and free-floating plants had the capacity to take up high levels of Cu, Zn, and Pb into their shoots. With roots having a concentration factor above 1, the terrestrial plants show efficient stabilization of Cd and Zn and emergent plants show corresponding stabilisation of Zn. In addition, Potamogeton natans, Alisma plantago-aquatica, and Filipendula ulmaria were used in a controlled experiment. The shoots of P. natans and the roots of A. plantago-aquatica were found to accumulate even higher concentrations of Zn, Cu, and Pb than found in the field-harvested plants. Similar results were found for Cd in shoots and Pb in roots of F. ulmaria. Our conclusion is that submersed plant species seem to be the most efficient for removal of heavy metals from storm-water.     

刺楸年轮中重金属含量动态变化及富集特性

为探索刺楸对受污染土壤重金属的富集和修复效应, 以南京栖霞山的乡土树种刺楸及其根际周边土壤为研究对象, 截取其根基部年轮盘及根际土壤样本, 采用ICP-AES法测定年轮及土壤样本中重金属(Cu、Cd、Cr、Mn、Ni、Pb、Zn)元素含量。结果表明: 栖霞山样地中的土壤受Mn、Pb和Zn污染最为严重, 存在Cu、Cd、Mn、Pb、Zn元素的高度复合污染, Cd、Cr、Cu、Ni、Zn在土壤和年轮中存在相关性, Mn和Pb则没有表现出明显的相关性; 刺楸修复受Cd、Mn、Pb、Zn污染的土壤效果并不显著, 更适用于Cr、Cu、Ni污染的土壤修复; 鉴于Cu元素含量变化特征, 刺楸也可以作为反映当地污染历史的记录载体; 刺楸年轮中的重金属元素之间存在交互作用, 其中Cd与Zn元素含量高度相关(r=0.984, p<0.01), 在刺楸年轮吸收重金属元素的过程中, Cu与Cd、Cr、Mn、Zn元素具有协同作用, Mn元素对其他元素有一定的拮抗作用。     

黄河口盐地碱蓬湿地土壤-植物系统重金属污染评价

以黄河口盐地碱蓬湿地为例,评价了淹水和非淹水区湿地表层土壤As、Cd、Cu、Cr、Pb和Zn 6种重金属的污染程度及其在土壤-植物系统中的迁移、富集特征,分析了不同积水深度和土壤理化性质对研究区土壤重金属含量的影响.研究结果表明,与土壤或沉积物质量标准相比,黄河口盐地碱蓬湿地土壤受As和Cd污染最严重,而其它重金属污染较轻;非淹水土壤Cd、Cr和Zn含量高于淹水湿地,而As、Cu和Pb则较低;而且淹水土壤As含量随积水深度增加而呈下降趋势,但积水深度对其他重金属含量的影响不明显.相关性分析结果表明,按照受土壤关键影响因子的不同重金属(除As外)可以分为两类:第一类为Cd、Cr和Zn,这些重金属含量受土壤pH值和盐分影响较大,且相互间存在显著正相关关系,表明它们可能有相同的来源;第二类为Pb和Cu,它们受土壤pH值、盐分和有机质的影响,且Pb和Cu之间存在显著正相关关系.除Cr、Cu和Zn外,重金属在盐地碱蓬的根系内一般不发生显著富集,但绝大多数重金属都表现出地上部分的含量比根系更高的现象.     

Bioaccumulation and translocation of heavy metals by Plantago major L. grown in contaminated soils under the effect of traffic pollution

The present study was performed at a heavy-traffic affected soil to examine the efficacy of bioaccumulation and translocation potentials of heavy metals by the naturally growing weed Plantago major. Heavy metals were analyzed in soil as well as in plant below- and above-ground parts along different distances from a heavy-traffic highway. All the investigated soil heavy metals, except Cd, varied significantly, while pH and E.C had no significant difference, with increasing distance from the highway. Likewise, there was a significant decrease of heavy metals in plant below- and aboveground parts. In addition, no significant difference between most soil and root heavy metals at 20 and 100 m as well as those at 500 and 750 m distance from the highway. The bioaccumulation factor (BF) of all heavy metals, except Cd and Sr, were less than unity at most distances. However, Cd showed relative BF decline with the distance in contrast to Sr, which increases as distance from the highway increases. On the other hand, the translocation factors (TF) of Cd, Co, Cu, Pb and Zn were higher at the distances far from the highway, while that of Fe, Cr and Sr were higher near the highway. Furthermore, the enrichment factor (EF) showed small variations, among the investigated heavy metals, with varying distances from the pollution source. It was found that soil Fe, Al, Cr, Ni, Sr, V and Zn had significant positive correlation with all investigated heavy metals in P. major roots. The higher TFs of Cd, Fe and Pb in P. major shoots makes it suitable for phytoextraction from soil, while the lower ratios of Al, Mn, V, Co, Ni, Cr, Zn, Cu and Sr make it suitable for their phytostabilization. Therefore, this plant can be used as a bioindicator and biomonitor for traffic related heavy metals.     

Preliminary study on heavy metals contamination of soil using solid phase speciation and the influence on groundwater in Bozanta–Baia Mare Area,Romania

Abstract

A preliminary study on soil contamination with heavy metals and As based on solid phase speciation according to the Tessier scheme and the influence on groundwater in an area under anthropogenic influence (Bozanta-Baia Mare, Romania) was conducted. The partitioning of Al, As, Cd, Cu, Fe, Mn, Pb and Zn in five fractions is discussed in relation to soil characteristics, pH, organic matter content, mineralogical composition and distribution of the same elements in airborne particulate matter. The airborne particulate matter contains high quantities of As, Cd, Cu, Pb and Zn as exchangeable fraction. The sequential extraction carried out on soil samples revealed the main role of Fe-Mn oxides surface in the immobilization of metals. Organic matter has a specific role in complexation of Cu, Pb, As and Al, since high contents of these metals were recovered in the oxidizable fraction. Cadmium has a high selectivity for carbonate minerals. The amendment of soil with natural fertilizer increases the exchangeable fraction of metals with the highest toxicity. The available fraction for plants (exchangeable + carbonate-bound species) exceeded the alert values in soil, therefore the continuous monitoring of the area is necessary. The soil is unsuitable for agricultural use due to high contamination on surface with toxic elements resulted from anthropogenic activities. Groundwater is contaminated with very toxic elements (As, Cd and Pb) but also with Cu, Mn and Zn and is unsuitable as supply for drinking water.     

Bioavailability and Concentration of Heavy Metals in the Sediments and Leaves of Grey Mangrove, <Emphasis Type="BoldItalic">Avicennia marina</Emphasis> (Forsk.) Vierh,in Sirik Azini Creek,Iran

The concentration and bioavailability of Ni, Cu, Cd, Zn, and Pb in the sediments and leaves of grey mangrove, Avicennia marina, were studied throughout Sirik Azini creek (Iran) with a view to determine heavy metals bioavailability, and two methods were used. Results show that Zn and Ni had the highest concentrations in the sediments, while Cd and Cu were found to have the lowest concentrations in the sediments. Compared to the mean concentrations of heavy metals in sedimentary rock (shales), Zn and Cu showed lower concentration, possibly indicating that the origin of these heavy metals is natural. A geo-accumulation index (I _geo) was used to determine the degree of contamination in the sediments. I _geo values for Zn, Cu, Pb, and Ni showed that there is no pollution from these metals in the study area. As heavy metal concentrations in leaves were higher than the bioavailable fraction of metals in sediments, it follows that bioconcentration factors (leaf/bioavailable sediment) for some metals were higher than 1.     

不同土壤生境下斑茅对重金属的富集特征

为了筛选Cu、Zn、Pb、Cd多重金属离子的富集植物,对不同土壤生境(铜铁矿、钨矿、铅锌矿和无矿场污染)的优势种斑茅(Saccharum arundinaceum(Retz.)Jeswiet)对Cu、Zn、Pb、Cd离子富集情况进行了调查。结果表明,斑茅对Cu、Zn、Pb、Cd离子有富集优势并以Cu富集显著,斑茅根系土壤与斑茅地上部Cu含量存在相关性(P<0.05),斑茅对Pb和Cd的富集与转运存在极显相关性(P<0.01);在强酸、多金属污染弃耕农田土壤中,斑茅不仅符合Cu超富集植物的特征,而且其对Zn、Pb和Cd3种重金属的富集系数和转运系数均>1。在Cd、Cu、Pb和Zn均低于国家土壤环境质量二级标准(GB15618-1995)的弃耕农田中,斑茅对Cu、Zn和Cd的富集系数均>1。研究表明,斑茅可以作为Cu、Zn、Pb、Cd多金属污染土壤的富集植物进行人工修复。