Assessment of Polycyclic Aromatic Hydrocarbons (PAH) and Heavy Metals in the Vicinity of an Oil Refinery in India

Petroleum products are one of the major sources of energy for industry and daily life. Growth of the petroleum industry and shipping of petroleum products has resulted in the pollution. Populations living in the vicinity of oil refinery waste sites may be at greater risk of potential exposure to polycyclic aromatic hydrocarbons (PAH) through inhalation, ingestion, and direct contact with contaminated media. PAH have often been found to coexist with environmental pollutants including heavy metals due to similar pollution sources. The levels and distribution patterns of Σ16 PAH (sum of the 16 PAH) and heavy metals (lead, copper, nickel, cobalt, and chromium) were determined in soil and sediment in the vicinity (5 km radius) of an oil refinery in India. Concentrations of Σ16 PAH in the soils and sediments were found to be 60.36 and 241.23 ppm, respectively. Higher amount of PAH in sediments as compared to soil is due to low water solubility of PAH, settled in the bottom of aquatic bodies. The levels of lead, copper, nickel, cobalt, and chromium (total) in soil were 12.52, 13.52, 18.78, 4.84, and 8.29 ppm, while the concentrations of these metals in sediments were 16.38, 47.88, 50.15, 7.07, and 13.25 ppm, respectively. Molecular diagnostics indices of PAH (Ratio of Phenanthrene/Anthracene, Fluranthene/Pyrene) calculated for soil and sediment samples indicate that the oil refinery environment is contaminated with PAH from petrogenic as well as pyrolytic origin and heavy vehicular traffic on the Agra- Delhi National highway. Sixteen PAH priority pollutants were detected in the United States in entire samples collected near oil refinery areas and concentrations of Σ16 PAH in soil was found to be 1.20 times higher than the threshold value for PAH in soil by ICRCL (Inter-Departmental Committee on the Redevelopment of Contaminated Land). This concentration could lead to disastrous consequences for the biotic and abiotic components of the ecosystem and may affect the soil quality, thus impairing plant growth and its bioaccumulation in food chain.     

生物淋滤技术在去除污泥中重金属的应用

利用微生物方法去除污泥中重金属（生物淋滤法）具有成本低,去除效率高,脱毒后污泥脱水性能好等优点,近年来在国际上备受关注,生物淋滤法采用的主要细菌为氧化亚铁硫杆菌（Thiobacillus ferrooxidans)和氧化硫硫杆菌（Thiobacillus thiooxidans),在其作用下,污泥中以难溶性金属硫化物被氧化成金属硫酸盐而溶出,通过固液分离即可达到去除重金属的目的,污泥的生物淋滤效果受温度、O2和CO2浓度,起始pH、污泥种类与浓度、底物种类与浓度、抑制因子、Fe^3 浓度等的影响,较为详细地介绍了生物淋滤法的作用机理及高效去除污泥中重金属的操作程序,并对其在环境污染治理方面的应用前景作了分析。     

底物种类和浓度对污泥重金属生物淋滤效果的影响

以生污泥为材料,研究单质硫(浓度分别为5、10、20 g/L)、FeSO4?7H2O (浓度分别为10、20 g/L）和硫代硫酸钠（浓度分别为10、20 g/L）三种底物的不同浓度对污泥中Zn、Cu、Pb、Cd、Cr和Ni六种重金属生物淋滤效果的影响。结果表明：单质硫的致酸性最好,第4天pH值就达到2.0左右,Zn、Cu、Pb、Cr和Ni的滤出量最大（原污泥Cd未检出）,并以底物投放浓度在10～20 g/L为佳。FeSO4?7H2O的致酸性和重金属滤出量较单质硫弱。硫代硫酸钠在浓度10 g/L时,致酸性和重金属的滤出量介于单质硫和FeSO4?7H2O之间,但浓度20 g/L时滤液呈碱性,重金属难于滤出甚至不滤出。     

城市污泥复合肥的肥效及其对小麦重金属吸收的影响

通过盆栽和大田试验,初步探讨了污泥复合肥种植小麦的肥效及其对小麦重金属吸收的影响。试验结果表明,污泥复合肥对小麦的增产效果和土壤的增肥效果明显优于化肥,等同于市售复合肥,它能促进植株生长发育,提高小麦产量,对土壤速效养分的积累有明显的促进作用;污泥复合肥处理的小麦籽粒中重金属Cu、Zn、Pb、Cd的含量均在国家食品卫生标准范围内。     

Evaluation of Heavy Metals and Associated Health Risks in a Metropolitan Wastewater Treatment Plant's Sludge for Its Land Application

The objectives of this study are to monitor the heavy metal concentrations in sludge samples collected from the Ankara Central Wastewater Treatment Plant (ACWWTP) in Turkey, check if these concentrations comply with the Turkish Regulation (Regulation Regarding the Use of Domestic and Urban Sludges on Soil), and evaluate possible health risks of heavy metals in sludge due to ingestion of sludge by a child. Monthly sludge samples were collected from the ACWWTP during 2012 and analyzed for seven heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn). According to the results from the study, heavy metal concentrations showed no common seasonal trend. All heavy metal concentrations, except for one sample in which Zn was found to be at the limit value, are below the Turkish Regulation limits. In addition, health risks calculations for the “child ingesting biosolids” pathway, which is one of the most critical pathways identified by the U.S. Environmental Protection Agency (USEPA) for land application, were carried out. Among the seven heavy metals, Pb contributed the most to the cumulative non-cancer health risks throughout 2012. Nevertheless, the results showed that cumulative non-cancer health risks associated with this pathway are within the acceptable non-cancer health risk level suggested by USEPA.     

Phytotreatment of Sewage Sludge Contaminated by Heavy Metals and Pahs by Co-Planting Sedum Alfredii and Alocasia Marorrhiza

High concentrations of heavy metals and organic pollutants in municipal sewage sludge are key factors limiting its use in agriculture. The objectives of this study were to decrease the heavy metal and polycyclic aromatic hydrocarbon concentrations in sewage sludge by phytotreatment and to determine, in a field experiment, whether co-planting is more effective than using a mono-crop of Sedum alfredii. Four treatments were used in the plot experiment: no sludge, no plants, S. alfredii and co-planting S. alfredii and Alocasia marorrhiza. The results showed that co-planting produced tubers and shoots of A. marorrhiza that were suitable as a safe animal feed and good organic K fertilizer, respectively. Co-planting was more effective than mono-planting at reducing concentrations of total Zn and diethylenetriaminepentaacetic acid (DTPA)-extractable Zn, Cd, and Cu in the sludge. Co-planting decreased the concentrations of DTPA-extractable heavy metals and benzo[a]pyrene (B[a]P) in the sludge significantly compared with the unplanted sludge. Decreases of 87, 75, 85, 31, and 64% were obtained for B[a]P and DTPA-extractable Zn, Cd, Cu, and Pb, respectively, compared with the fresh sludge. These results indicate that co-planting can reduce significantly the environmental risks associated with heavy metals and B[a]P in sewage sludge for further disposal.     

Role of Iron-Oxidizing Microorganism in Bioleaching of Heavy Metals From Sewage Sludge Contaminated with Textile Dyes

This article reports the role of indigenous iron-oxidizing microorganisms in bioleaching of heavy metals from anaerobically digested sewage sludge in presence of toxic dyes namely, methylene blue (MB), Remazol black B (RBB) and mixture of both the dyes (DM). To achieve this goal, different concentrations of dyes (0, 500, 10,000, 15,000 and 25,000 mg/L) were added to the sewage sludge (initial pH ～ 7) and subsequently, the solubilization of heavy metals (Cu, Ni, Zn and Cr) was measured at time intervals of 48 h for 16 days. The results showed that an increase in dye concentration adversely affected the population of indigenous iron-oxidizing microorganisms, thereby decreased the bioleaching of metals. The metal solubilization from sludge is more adversely affected in presence of RBB and DM than MB. In majority of cases, the maximum metal solubilization was recorded at dye concentration of 5,000 mg/L. Two factor analyses (ANOVA) suggests the impact of both factors: dye concentration and dye type on metal leaching rate in sludge system.     

Chemical Fractionation and Heavy Metal Distribution in Agricultural Soils,North of Jordan Valley

Thirty-nine soil samples were collected on a grid pattern from the north of the Jordan Valley. These samples were subjected to geochemical, mineralogical and textural analyses. The investigated soil is characterized by medium texture and to a less extent moderately coarse and coarse texture. The value of TDS shows a slight increase in the southern part of the study area toward the Dead Sea due to the increase in temperature and decrease of the amount of precipitation. The organic matter content and P ₂ O ₅ values show significant variations that coincide with agricultural activity and application of fertilizers and pesticides in the investigated area. In the samples collected, CEC values are slightly decreased from north to south parts of the study area where the abundance of organic matter and clay minerals are low. The study found that the enrichment factors of the measured heavy metals Pb, Cd, As and Hg are 2.8, 11.9, 20 and 17 respectively. Accordingly, the soil of the study area can be considered moderately contaminated with respect to As and Hg and uncontaminated to moderately contaminated with respect to Pb and Cd. The distribution of the measured heavy metals are affected by various geochemical factors including pH, clay content, cation exchange capacity, organic matter content and total phosphate content. Sequential extraction procedure was used in order to determine the percentage of the Pb, Cd and As present in five geochemical fractions of the examined soil samples. It was found that Pb and As are mainly associated with the residual phases and are relatively immobile. On the other hand Cd is enriched in the carbonate phase of the analyzed soil samples. Based on the sequential extraction procedure it is possible to suggest the sequence of metal mobility as: Cd > Pb > As.     

Chemical Fractionation and Soil-to-Plant Transfer Characteristics of Heavy Metals in a Sludge Deposit Field of the River Ruhr,Germany

The presented study assessed the heavy metal contamination risk in a former sludge deposit field of the River Ruhr in Essen, Germany. Therefore, the temporal and spatial distribution in soils and plants, chemical fractionation, mobilization potential, and transfer characteristics have been investigated. Soil samples, roots and shoots of rushes (Juncus sp.), and stem wood disks of willows (Salix sp.) were analyzed for Zn, Cu, Pb, Ni, Cr, and Cd. Plant available and mobile heavy metal portions have been determined using a sequential extraction procedure. The results show that the soils and the rushes are highly contaminated, although there is a considerable decrease compared to initial concentrations some 20 years ago. The willows show only small heavy metal enrichment. pH induced mobilization potential in soil is high for Cd, Zn and Ni. Additionally, these elements contain high portions of plant-available fractions. High transfer rates from soil to roots and very high rates from roots to shoots of rushes have been determined for Cd and Zn, indicating an accumulation of these elements in shoots of rushes. The rushes reflect the temporal and spatial heavy metal distribution in soil and might thus be used as a bioindicator or for phytoremediation.     

污泥的农林处置与利用

1　污泥处置与农林利用现状污泥处置与利用 ,乃当前环境科学中的重要课题。一些污水处理的专家认为 ,污泥处置是污水处理厂当前迫切要解决的难度最大的问题。污泥的处置主要包括农用、填埋、焚烧、排海等。据1 996年资料报道 ,世界上 1 2个发达国家对污泥的处置方式 (表 1 ) ,45.3%为农用 ,38%为填埋 ,1 0 .5%为焚烧 ,6.0 %为排海。西欧、美国和英国的污泥处置 ,西欧以填埋为主 ,美国和英国以农用为主 ,加拿大以焚烧为主 (占 40 % ) [1 ] 。 1 991年和1 998年 ,美国和欧盟已规定禁止向海洋倾倒污泥[1 1 ] ,并且一些发达国家已经明令禁止焚烧…     

Environmental Evaluation of Different Treatment Processes for Sludge from Urban Wastewater Treatments: Anaerobic Digestion versus Thermal Processes (10 pp)

Background, Aims and Scope Huge amounts of sewage sludge, that need to be handled, are generated all around the world from wastewater treatment plants and its management in an economically and environmentally acceptable way has become a matter of increasing importance during the last few years. In this paper, we make use of Life Cycle Assessment (LCA) to compare biological and thermal processes, that is to say, anaerobic digestion versus pyrolysis and incineration. This paper will complete the analysis performed in a wastewater treatment plant, where sludge post-treatment was identified as one of the main contributors to the environmental impact on the global system. Methods LCA is a tool for evaluating the environmental performance of goods as well as processes or services (collectively termed products). ISO 14040 defines LCA as a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a system throughout its life cycle: from the production of raw materials to the disposal of the waste generated. In this study, data relating to the actual scenario from an existent wastewater treatment plant were considered. Both bibliographical and real data from existing facilities were used for the thermal processes proposed. The Centre of Environmental Science (CML) of Leiden University's methodology was chosen to quantify the potential environmental impacts associated with the different scenarios under study. The software SimaPro 5.1 was used and CML factors (updated in 2002) were chosen for characterisation and normalisation stages. Results and Discussion In a previous study, sewage sludge was found to be a critical point in the environmental performance of a wastewater treatment plant, so different alternatives have been tackled here. Anaerobic digestion followed by land application of pasty sludge comprises both energy recovery and nutrient recovery. Other thermal processes, such as incineration or pyrolysis, allow energy recovery (both electrical and thermal) and, although nutrients are lost, new co-products are produced (tar and char at pyrolysis). Here, the most adverse case (that is to say, the total amount of heavy metals is supposed to be released from the sludge and reach the environment) was applied to consider the most negative impact due to sludge spreading in agricultural soils; so more research is required in order to establish the precise amount of heavy metals that is effectively uptaken by the plants and crops as well as the amount that is transferred to another phase as a leachate. Thermal processes are presented here as a good option to recover energy from the sludge; although the value of nutrients is lost. Tar and char, co-products from pyrolysis, are good examples that were evaluated here, recycling of bottom ashes from sludge incineration or manufacture of ceramic materials from sludge are other options to be studied in the near future. Conclusion During the last few years, several opinions have been declared in favour of land application, incineration or pyrolysis, but many voices have also spoken out against each one. To obtain general conclusions for an overall comparison of different post-treatment of urban wastewater sludge is not easy as there are many contradictory aspects. The most effective utilisation of sewage sludge implies both energy and material re-use, but this is not always possible. Nevertheless, we think that land application of digested sludge is an acceptable option, probably not the best but at least a good one, for sludge treatment as long as efforts are focused on the minimisation of heavy metal content in the final cake.     

Bio-Acidification and Leaching of Metals,Nitrogen, and Phosphorus from Soil and Sludge Mixtures

Soil and wastewater treatment sludge are commonly brought together in mixtures for a variety of beneficial purposes. The mixtures contain bioacidifying (i.e., sulfur-oxidizing) microorganisms that can easily be activated through providing the appropriate substrate and environmental conditions. In this study, contaminated soil and sludge mixtures were subjected to controlled bio-acidification and the impacts of the process on the partitioning of heavy metals, nitrogen, and phosphorus were examined. Three successive bio-acidification cycles resulted in significant leaching of metals from sludge. The leaching results, expressed as fraction of total mass of metals in the sludge, averaged 67% for Cr, 96% for Ni, 24% for Zn; 16% for Cu; 23% for Cd; and 96% for Pb. Bio-acidification of the sludge also converted 28 to 45% of the organic nitrogen into ammonia and increased the soluble orthophosphates fraction of total phosphorus by approximately 18 to 20%. Bio-acidification also resulted in significant metals leaching from the contaminated soils in the soil/sludge mixtures. Soil/sludge mixtures were prepared using six soil particle sizes (less than 0.075?mm to 2.38?mm) contaminated with 22,500?mg/kg Zn, 14,000?mg/kg Pb, 1500?mg/kg Cr, 9500?mg/kg Cu, 1000?mg/kg Ni, and 1000?mg/kg Cd. The addition of metals to the soil inhibited the sulfur-oxidizing microorganisms, preventing bio-acidification in the mixtures containing 4 to 50?g soil in 130?ml sludge, and considerably slowing bio-acidification in the mixtures containing 1 to 3?g soil. Using a mixture that contained 2-g soil samples, three successive bio-acidification cycles resulted in significant cumulative metals leaching results. The leaching results, expressed as percentage of the mass of metals added to the soil, were in the range of 56 to 98% for Cr, 77 to 95% for Zn, 33 to 66% for Ni, 64 to 82% for Cu, and 10 to 33% for Pb, with the higher results in each range belonging to the larger size soil particles. On the other hand, only Cr was leached in neutralized soil samples. The results confirmed the potential for inhibition of the sulfur-oxidizing microorganisms and bio-acidification in contaminated soil/sludge mixtures, and the significant impacts of bio-acidification on the mobility of metals, nitrogen, and phosphorus. In addition, the results confirmed the potential for using controlled bioacidification for removing heavy metals from contaminated soil using the indigenous sulfur oxidizing microorganisms in sludge.     

Organochlorine,Organophosphoric and Organotin Contaminants,Aromatic and Aliphatic Hydrocarbons and Heavy Metals in Sediments of the Ports from the Polish Part of the Vistula Lagoon (Baltic Sea)

The concentrations of polycyclic aromatic and petroleum hydrocarbons, polychlorinated biphenyls, dioxins, organochlorine and organophosphoric pesticides, tributyltin and metals were determined in sediments of the approach fairways to the main ports in the Polish part of the Vistula Lagoon and of the Elbl?g River. Analyzed sediments contained low concentrations of all contaminants, except petroleum hydrocarbons. The average petroleum hydrocarbons’ (PHCs) concentration was 630 mg kg^?1, indicating significant pollution with petroleum hydrocarbons. The highest concentrations of analyzed contaminants were identified in the vicinity of Elbl?g, part of the Vistula Lagoon under the most anthropogenic pressure.     

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.     

Distribution of Heavy Metals and Arsenic in Soils of Belgrade (Serbia and Montenegro) 1

Soils of the urban and suburban area of Belgrade have been hardly studied, especially concerning their concentrations of potentially toxic metals. The present paper is aimed at determining the possible pollution in soils. The total acid soluble concentrations of heavy metals and As in the samples were determined. It was found that they were arranged in the order Zn > Ni > Pb > Cr > Cu > As > Hg > Cd in samples collected in the examined area (the order of the elements is based on their arithmetic mean concentrations). In all the samples collected at 0–10 and 40–50 cm depths from 46 selected sites, the contents of Pb and Zn were lower at the depth 40-50 cm. Using target values given by the Dutch Ministry of Housing, Spatial Planning and Environment, it may be concluded that Belgrade soil can, for the most part, be regarded as unpolluted. Traffic seems to be one of the main sources of these metals, but the influence of other factors cannot be excluded.     

Phytoaccumulation of Heavy Metals in Natural Plants Thriving on Wastewater Effluent at Hattar Industrial Estate,Pakistan

The objective of this research was to compare the potential of native plants for the phytoaccumulation of heavy metals (HM). Thirteen predominant plant species (including trees, bushes and grasses) namely Ricinus communis, Ipomoea carnea, Cannabis sativa, Parthenium hysterophorus, Acacia nilotica, Dalbergia sissoo, Acacia modesta, Solanum nigrum, Xanthium stromarium, Chenopodium album, Cynodon dactylon, Eleusine indica, and Dactyloctenium aegyptium were collected from the wastewater originated from Hattar industrial estate of Pakistan, Plants shoots and roots were analyzed for heavy metals / metalloid: Pb, Cr, Cd, Zn, Fe, Ni, and As. Among plant species, the accumulation potential for HM varied depending on the type of element. Regardless of the plant species, HM concentrations varied in the order of Fe > Zn > Cr > Pb > Ni > Cd > As. Tree species of R. communis, A. nilotica, A. modesta, and D. sissoo exhibited an enhanced concentrations of metals. Accumulation pattern of Fe, Pb, Cd, and As in plants could be related to the HM composition of soil and wastewater. Most of the species exhibited higher HM composition in the root as compared to shoot. The species that found with greater ability to absorb HM in the root, got higher HM concentrations in its shoot. Shoot tissue concentrations of HM were attained by the species as D. sissoo > A. modesta > A. nilotica > R. communis > I. carnea > C. album > E. indica > P. hysterophorus > S. nigrum > C. sativa > D. aegyptium > X. strumarium > C. dactylon. Based on results, tree plants were noticed as higher accumulators of HM in polluted soils.     

Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea Coast of Yemen

A detailed analytical study using combined normal phase high pressure liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) of Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea was undertaken. This investigation involves a preliminary assessment of the sixteen parent compounds issued by the U.S. Environmental Protection Agency(EPA). The study revealed measurable levels of Σ PAHs (the sum of three to five or six ring parent compounds) (49.2 ng g⁻¹ dry weight) and total PAHs (all PAH detected) (422.1 ng g⁻¹ dry weight) in edible muscle of fishes collected from the Red Sea. These concentrations are within the range of values reported for other comparable regions of the world. Mean concentrations for individual parent PAH in fish muscles were; naphthalene 19.5, biphenyl 4.6, acenaphthylene 1.0, acenaphthene 1.2, fluorene 5.5, phenanthrene 14.0, anthracene 0.8, fluoranthene 1.5, pyrene 1.8, benz(a)anthracene 0.4, chrysene 1.9, benzo(b)fluoranthene 0.5, benzo(k)fluoranthene 0.5, benzo(e)pyrene 0.9, benzo(a)pyrene 0.5, perylene 0.2, and indeno(1,2,3-cd)pyrene 0.1 ng g⁻¹ dry weight respectively. The Red Sea fish extracts exhibit the low molecular weight aromatics as well as the discernible alkyl-substituted species of naphthalene, fluorene, phenanthrene and dibenzothiophene. Thus, it was suggested that the most probable source of PAHs is oil contamination originating from spillages and/or heavy ship traffic. It was concluded that the presence of PAHs in the fish muscles is not responsible for the reported fish kill phenomenon. However, the high concentrations of carcinogenic chrysene encountered in these fishes should be considered seriously as it is hazardous to human health. Based on fish consumption by Yemeni‘s population it was calculated that the daily intake of total carcinogens were 0.15 μg/person/day. This revised version was published online in August 2006 with corrections to the Cover Date.     

Accumulation of Heavy Metals in Water,Sediments and Wetland Plants of Kizilirmak Delta (Samsun,Turkey)

In this study, concentrations of heavy metals (Fe, Mn, Ni, Co, Zn, Cu, and Pb) were measured in water bodies including streams, bottom sediments and various wetland plants of K?z?l?rmak Delta. K?z?l?rmak Delta is one of the largest and the most important natural wetlands in Turkey and has been protected by Ramsar convention since 1993. The heavy metal concentrations in water were found lower than that of national standards for protected lakes and reserves. In bottom sediments and wetland plants, however, the accumulated amounts of different heavy metals varied in the following order: Fe>Mn>Zn>Ni>Co>Cu>Pb, and Fe>Mn>Zn>Ni>Co respectively. Heavy metal uptake of Hydrocharis morsus-ranae and Myriophyllum verticillatum plants among others were found far above the toxic levels and they might be used as bio-indicators and heavy metal accumulators in polluted natural areas.     

Effect of Heavy Metals (Cd, Cu) on the Gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminariajaponica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal (Cd) distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu up to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning (the first day) of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd- and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods.All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.     

Phytoaccumulation of Heavy Metals in Natural Vegetation at the Municipal Wastewater Site in Abbottabad,Pakistan

Heavy metal accumulation in crops and soils from wastewater irrigation poses a significant threat to the human health. A study was carried out to investigate the removal potential of heavy metals (HM) by native plant species, namely Cannabis sativa L., Chenopodium album L., Datura stramonium L., Sonchus asper L., Amaranthus viridus L., Oenothera rosea (LHer), Xanthium stramonium L., Polygonum macalosa L., Nasturtium officinale L. and Conyza canadensis L. growing at the municipal wastewater site in Abbottabad city, Pakistan. The HM concentrations varied among plants depending on the species. Metal concentrations across species varied in the order iron (Fe) > zinc (Zn) > chromium (Cr) > nickel (Ni) > cadmium (Cd). Majority of the species accumulated more HM in roots than shoots. Among species, the concentrations (both in roots and shoots) were in the order C. sativa > C. album > X. stramonium > C. canadensis > A. viridus > N. officinale > P. macalosa > D. stramonium > S. asper > O. rosea. No species was identified as a hyperaccumulator. All species exhibited a translocation factor (TF) less than 1. Species like C. sativa, C. album and X. stramonium gave higher (> 1) biological concentration factor (BCF) and biological accumulation coefficient (BAC) especially for Fe, Cr and Cd than other species. Higher accumulation of heavy metals in these plant species signifies the general application of these species for phytostabilization and phytoextraction of HM from polluted soils.