The protective role of melatonin under heavy metal-induced stress in Melissa Officinalis L.

Heavy metals, due to their inability to degrade, pose a serious environmental and nutritional problem. The accumulation of essential and non-essential heavy metals in living organisms reduces normal growth and development, resulting in acute poisoning, disease and even death of organisms. Melatonin is a very important multifunctional molecule in protecting plants from oxidative stress due to its ability to directly neutralize reactive oxygen species (ROS). Also, melatonin has a chelating property, which may contribute in reducing metal-induced toxicity. In this paper, the protective role of melatonin in counteracting metal-induced free radical generation was highlighted. Using the HPLC-FLD technique melatonin was identified and quantified in the roots and leaves of lemon balm ( Melissa officinalis L.), grown under photoperiod conditions. Furthermore, the response of plants pre-treated with exogenous 0.1 mM melatonin to the increased zinc (Zn) and cadmium (Cd) concentrations was observed, with changes in mineral (Ca, Mg), physiological and antioxidant status of the plant during heavy metals stress. The obtained melatonin concentrations were the highest published for dry plants so far. Elevated Cd and Zn levels in soil caused alternation in biochemical and physiological parameters of lemon balm leaves and roots. However, melatonin pre-treatment increased plant tolerance to heavy metals stress. Increased Cd and Zn uptake and their translocation into the leaves were also improved, indicating the possible use of melatonin in phytoremediation.     

The Assessment of Phytoremediation Potential of Invasive Weed Amaranthus spinosus L.

Presently the environment is heavily polluted by various toxic metals, which creates danger for all living beings. Heavy metals are toxic above certain threshold levels. Phytoremediation is an emerging technology which is quite a novel technique of cleaning polluted sites through the use of plants. Phytoremediation methods are comparatively cheap and ecologically advantageous, compared to conventional and physicochemical methods like precipitation, evaporation and chemical reduction. In this respect, plants can be compared to solar-driven pumps capable of extracting and concentrating certain elements from their environment. Amaranthus spinosus, an invasive weed seen on road sides and bare land belonging to the family Amaranthaceae, was selected for the present study. A greenhouse experiment was conducted and consisted of a range-finding test and definitive test for various concentrations of heavy metals Cu, Zn, Cr, Pb and Cd. Plants were grown in soil treated with different concentration of metals depending upon the threshold level. The bio-organics of the plant such as soluble sugar, protein, lipid, phenol, amino acid and photosynthetic pigments were estimated after 30?days of treatment. The bio-organics showed profound variation in response to accumulation of heavy metals. Accumulation of Cu, Pb and Cd was high in the roots followed by stem and leaves and that of Zn and Cr remained high in aerial parts. A steady increase was noticed in the bioaccumulation of copper, zinc and cadmium on enhancing the concentration of the corresponding metal in the soil. The bioconcentration factor and translocation factor were above unity in most of the treatments and increased as the concentration of treatment increased which indicated that A. spinosus is a potential agent for heavy metal accumulation and translocation.     

Polycyclic aromatic hydrocarbons (PAHs) pollution recorded in annual rings of gingko (Gingko biloba L.): Regression analysis and comparison to other pollutants

Further interesting information about contamination recorded in gingko annual rings is revealed in this paper. The degradation degrees of varied PAHs in gingko trunk, range 2.4 to 3.4%, are evaluated by using regression analysis and confirmed to depend upon their molecular sizes and chemical properties. For other lipophilic compounds, the translocation and diffusion behaviors conform to our donut model of PAHs in previous work, while for hydrophilic contaminants, the translocation and diffusion are more complicated owing to the second uptake pathways by roots. Further, the gingko tree exhibits selective absorption to heavy metals, such as Cu, Cd, Zn, Cr, Pb, Ni, Fe, and Mn. The relative accumulation degrees of these heavy metals are estimated by comparing to Fe in the soil and the gingko tree, and the result suggests that the gingko accumulates Cr, Cd and Pb from the soil. However, the metals in annual rings might not reflect historical environment changes for their diffusive nature in water-sapwood.     

Phytochemical databases of Chinese herbal constituents and bioactive plant compounds with known target specificities

Two databases have been constructed to facilitate applications of cheminformatics and molecular modeling to medicinal plants. The first contains data on known chemical constituents of 240 commonly used Chinese herbs, the other contains information on target specificities of bioactive plant compounds. Structures are available for all compounds. In the case of the Chinese herbal constituents database, further details include trivial and systematic names, compound class and skeletal type, botanical and Chinese (pinyin) names of associated herb(s), CAS registry number, chirality, pharmacological and toxicological information, and chemical references. For the bioactive plant compounds database, details of molecular target(s), IC50 and related measures, and associated botanical species are given. For Chinese herbs, approximately 7000 unique compounds are listed, though some are found in more than one herb, the total number for all herbs being 8264. For bioactive plant compounds, 2597 compounds active against 78 molecular targets are covered. Statistical relationships within and between the two databases are explored.     

Study of a heavy metal biosorption onto raw and chemically modified Sargassum sp. via spectroscopic and modeling analysis

In this study, raw and formaldehyde-modified Sargassum sp. are used for heavy metal removal. A series of experiments shows that the chemical modification by formaldehyde improves biosorption capacity by approximately 20%. Solution pH plays an important role in the metal uptake. According to X-ray photoelectron spectroscopic and Fourier transform infrared spectroscopic analysis, the possible organic functional groups in the metal binding include carboxyl, ether, alcoholic, hydroxyl, and amino functional groups. A new model that includes a series of coordination reactions among a generalized functional group, alkaline earth metal ions and heavy metal ions, is developed for simulation of biosorption process. The model well describes the single- and multiple-species metal biosorption process under different conditions such as pH. The biosorption of heavy metals is due to the ion exchange between the heavy metals and alkaline earth metals and their adsorption onto the free sites of the seaweeds. Slightly more than half of the metal uptake is due to ion exchange. The metal affinity for the functional groups follows a descending order of lead > copper > alkaline earth metal.     

重金属有效态与土壤环境质量标准制订

制订合适的土壤环境质量标准是评价土壤健康质量及食品安全的核心问题,而土壤重金属有效态对制定土壤环境质量标准具有重要意义。土壤重金属有效态主要指植物有效态,它与重金属形态关系密切。影响土壤重金属有效态的因素很多,主要包括:土壤pH值、氧化还原电位、CEC、有机质含量、粒径组成(黏粒含量)、铁铝锰氧化物含量、植物种类、土壤微生物、土壤温度的高低、重金属来源等。化学试剂浸提法是测量重金属生物有效性的常用方法,所用化学试剂主要有三类:弱(稀)酸、络合剂和中性盐,中性盐由于对土壤pH值影响小而受到重视。我国现行土壤质量标准采用土壤重金属总量和pH两个因素为依据,但是不少学者认为,该标准仅适用于重金属有效态较高的土壤,而不能反映重金属有效态含量较低土壤的实际状况。     

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.     

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan,China

In order to fully understand the morphological characteristics and pollution status of heavy metals in the dewatered sludge of Huainan Municipal sewage treatment plant, the physical and chemical properties were analyzed, and the content and occurrence forms of heavy metals (As, Cu, Zn, Pb, Cd, Cr, and Ni) in the sludge were studied using the geological accumulation method (Igeo), risk assessment coding method (RAC), and potential ecological risk index method to evaluate the ecological risk. The results showed that the municipal sludge in Huainan was rich in nutrients, with good prospects for agricultural utilization. There were differences in the morphological distributions of different heavy metals. The Igeo values for Ni, As, Cr, and Pb were below 0. The results of RAC indicated that the risk level of Cr in sludge was a low risk, and those of other heavy metals were moderate risks. The potential ecological risk of Cd had the highest potential ecological risk, and the other six metals were of low ecological risk. This conclusion can provide basic data and a theoretical reference for the comprehensive utilization of sludge in sewage treatment plants.     

Uptake of Heavy Metals by Lupin Plants in Artificially Contaminated Sand: Preliminary Results

The aim of this study was to investigate the tolerance, uptake and accumulation of several metals of environmental interest by lupin plants. The effects of different metals on those parameters were evaluated individually as well as in groups, since the latter matches more closely real environmental conditions. The chemical form of some metals was also taken into consideration. Lupin plants were grown in different batches of sand artificially contaminated with Pb(II), Cd(II), Cr(III), Cr(VI), CH 3 Hg + and Hg(II) (each metal at the 50 mg L m 1 level) or their combinations. After 4 weeks of growth, the results indicated that lupins were quite tolerant to Cd(II), Pb(II), Cr(III) and Hg(II) since contamination with those metals did not cause significant weight differences between metal-treated and control plants. On the other hand, the presence of Cr(VI) and CH 3 Hg + induced severe signs of toxicity. Metal accumulation in lupins plants was influenced not only by the chemical form of the analyte but also by the co-presence of other metals. Metal concentration in the plants once harvested were found to be 4.9 g kg m 1 , 2.3 g kg m 1 , 0.4 g kg m 1 and 0.2 g kg m 1 for Cd(II), Hg(II), Pb(II) and Cr(III), respectively. Metals were preferentially accumulated in roots although a fast translocation to shoots was detected for Hg(II).     

Heavy metal concentrations in soil and wild plants growing around Pb-Zn sulfide terrain in the Kohistan region, northern Pakistan

This study investigates the soil and wild plants of the Pb-Zn sulfide bearing mineralized zone of Indian plate (IP) in the Pazang and Lahor sites, Kohistan region, northern Pakistan. Soil and plants were analyzed for major cations (Na, K, Ca, Mg, Fe, Mn) and heavy metals (Pb, Zn, Cd, Cu, Cr, Ni, Co) concentrations by using atomic absorption spectrometer. Metal concentrations were used to quantify pollution contamination factors such as pollution load index (PLI) and plant bioaccumulation in soil and plants developed in mineralized zones in the Lahor and Pazang sites and an unmineralized zone (reference sites) of the Besham area. Soil and plants of the mineralized zone and surrounding areas have higher heavy metal (HM) contamination (P < 0.01) as compared to the reference site, which can be attributed to the dispersion of metals due to mining. Furthermore, in mineralized zones, the Lahor site was more contaminated than the Pazang site. This high HM contamination may pose potential threats to local communities of Kohistan region. The results also showed that plant species (Plectranthus rugosus, Rumex hastatus, Fimbristylis dichotoma, Heteropogon conturtus and Myrsine Africana) were the best HM accumulators.     

Importance and difficulties of research on metal speciation in the aquatic ecosystem: an ecologist's viewpoint

Post-war research on the role of heavy metals in the environment was stimulated by a new sensitivity towards nature, the increasing impact of human activities on the environment, continuous progress in analytical chemistry and the development of radioecology. Nowadays, very low concentrations of total metal can be quantified in the various compartments of the ecosystem (e.g. water, sediment, suspended particles, plants and animals), and the physical and chemical forms of the metal identified. A current difficulty is how to evaluate the role of the various metal forms in the natural ecosystem. The major issues to be tackled are: variations over time of metal species in relation to the influence of environmental variables; the fact that the availability of the metal varies with the plant and animal species; the ability of the organism to select the metals and their forms; the influence of suspended particles and chelating substances on metal uptake, detoxification strategies and synergic and antagonistic effects. The advantages and disadvantages of monitoring using bioaccumulator organisms are discussed.     

The Design of Experiment as a Tool to Model Plant Trace-Metal Bioindication Abilities

Bioindicator plants are species that have the capacity to linearly uptake some elements (metal and metalloids) from the growing substrate, thus reflecting their concentration in the soil. Many factors can influence the uptake of these elements by plants, among which is the simultaneous presence of several metals, a common situation in contaminated or natural soils. A novel approach that can be used to validate the bioindication ability of a species growing on a polymetallic substrate is the design of experiment (DoE) approach. The aim of the present study was to apply the DoE in full factorial mode to model the Cu, Cd, Pb, Zn, and Cr bioindication capacity of Polygonum aviculare, used as the model plant. The results showed that P. aviculare has the ability to bioindicate Cd and Cr with a linear uptake (from 0.35 to 6.66, and 0.1 to 3.4 mg kg⁻¹, respectively) unaffected by the presence of other metals. Conversely, the uptake of Pb, Cu, and Zn is strongly influenced by the presence of all the studied metals, making their concentration in the plant shoot not proportional to that of the soil. In conclusion, these preliminary results confirmed that the DoE can be used to predict the bioindicator abilities of a plant for several elements at the same time and to evaluate the interactions that can be established between variables in the growing medium and in the plant itself. However, more studies including other plant species are needed to confirm the effectiveness of this method.     

Investigation of effects of cadmium,lead, nickel and vanadium contamination on the uptake and transport processes in cucumber plants by TXRF spectrometry

Uptake and transport processes of some essential nutrient elements (K, Ca, Fe, Mn and Zn) in cucumber plants grown in contamination-free or in contaminated (10⁻⁵ M Cd, Ni, Pb or V) nutrient solutions containing iron in the chemical form of Fe(III)-citrate, Fe(III)-EDTA or Fe-chloride were studied by total reflection X-ray fluorescence spectrometry (TXRF). The root samples were dissolved using a microwave assisted acidic digestion procedure, while the xylem sap samples were directly analysed after addition of internal standard. It was established that the accumulation in the roots and the transport rate of the four heavy metals investigated increase in order of V<Ni≪Cd<Pb and V≪Pb<Cd<Ni, respectively. Due to the relatively low accumulation and transport of V in the plant it has the smallest influence on the uptake and transport of the essential elements. Cd hampers the water uptake and thereby the amount of all transported essential elements, and in addition results in higher accumulation of Ca, Fe and Zn in the roots. Pb contamination leads to a drastic reduction of Ca accumulated in the roots and mostly a slight increment in the transport of the essential nutrient elements investigated. Ni contamination hinders the transport of K and Zn, and leads to a higher accumulation of Mn in the roots. The chemical form of iron and hereby the presence of complex forming agents play an important role first of all for the uptake and transport processes of Fe and K.     

The use of vetiver for remediation of heavy metal soil contamination

The use of Vetiveria zizanioides (vetiver) was studied to evaluate its efficiency for the remediation of soils contaminated by heavy metals. Vetiver plants were tested for Cr, Cu, Pb and Zn. Phytoextraction and bioremediation experiments were carried out by irrigating the vetiver plants and the dry plants with solutions containing suitable amounts of Cr, Cu, Pd and Zn. The concentrations of the heavy metals were determined in both experiments in shoot and root parts of vetiver plants using inductively coupled plasma atomic emission spectroscopy after a mineralization step. Phytoextraction experiments showed a poor efficiency of vetiver for Cr and Cu uptake (both less than 0.1% in shoots and roots after 30 days), but a quite high capability of Pb and Zn uptake (0.4% in shoots and 1% in roots for Pb and 1% both in shoots and in roots for Zn, after 30 days). For these reasons the vetiver plant can be considered a quite good “hyperaccumulator” only for Pb and Zn. As for bioremediation experiments, the vetiver plant showed heavy metal uptake values significantly lower than those obtained with other biological substrates. Figure Vetiver plant     

Determination of heavy metal concentrations in plants exposed to different degrees of pollution using ICP-AES

Plant samples (Plantago lanceolata - narrow leaf plantain and Cichorium endiviae - endive) were collected in the surroundings of heavy metal emission sources and in other less contaminated areas. After digestion in a closed microwave system using HNO(3), the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, and Zn were determined using ICP-AES. Detection limits for all the elements of interest are given. Differences in heavy metal uptake rate between both plant species were observed. The uptake is more intensive for endive than for narrow leaf plantain. High concentrations of some heavy metals were determined in the unwashed plant samples as a result of exposure to aerosols. Tukey's statistical test was used to confirm the discrepancy of Cr concentration in plant samples from various areas. Washing the leaves with water was found to remove a large amount of water-soluble aerosols.     

北部湾文蛤体内氧化逆境标志物对重金属积累的响应研究

研究目的是通过评价北部湾文蛤（Meretrix meretrix）体内7种氧化逆境标志物对重金属积累的响应, 筛选出能够灵敏指示海域现场重金属污染压力的生物标志物. 2011年秋季, 在北部湾沿海潮间带6个典型站位采集文蛤样品, 测定软组织中重金属含量及鳃、内脏中7种氧化逆境标志物水平, 分析其空间、组织分布特征, 然后对标志物水平与重金属含量进行相关性分析. 结果表明, 文蛤软组织中重金属积累量和氧化逆境标志物水平在站位间存在很大差异. 大多数氧化逆境标志物具有明显的组织差异性, 鳃中的超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPx）、谷胱甘肽转硫酶（GST）活性以及还原型谷胱甘肽（GSH）、氧化型谷胱甘肽（GSSG）含量均高于内脏, 过氧化氢酶（CAT）在内脏中的活性较高, 而硫代巴比妥酸反应物（TBARs）在两组织中无明显的分布差异. 多种重金属共存的情况下, 鳃的GSH/GSSG与软组织Cd含量有显著相关性; 4种抗氧化酶中, 鳃CAT对Pb具有显著正响应, 内脏CAT、GST对As具有显著负响应. 鳃TBARs分别与Hg、Cd含量呈显著正相关、负相关, 内脏TBARs则与Pb含量呈负相关, 表明这些标志物能够灵敏指示重金属对文蛤抗氧化防御机能的影响, 适于作为评价北部湾重金属污染压力的指标.     

Validation of the methods for heavy metal speciation in soils and sediments

The knowledge of the chemical forms of metals is used to assess their availability and uptake by plants, and in sediments the forms of metals determine their transport and mobility in the aquatic media. This information may be obtained by determining chemical forms of metals (speciation) or different phases in which the metals are bound, obtained by applying extraction schemes. The analytical methods used include different steps and all of them must be validated. We report here the recommendations to minimize the errors in this kind of analysis. For validation the use of Certified Reference Materials (CRMs) and the participation in interlaboratory exercises are highly recommended.     

PlantPIs--an interactive web resource on plant protease inhibitors

PlantPIs is a web querying system for a database collection of plant protease inhibitors data. Protease inhibitors in plants are naturally occurring proteins that inhibit the function of endogenous and exogenous proteases. In this paper the design and development of a web framework providing a clear and very flexible way of querying plant protease inhibitors data is reported. The web resource is based on a relational database, containing data of plants protease inhibitors publicly accessible, and a graphical user interface providing all the necessary browsing tools, including a data exporting function. PlantPIs contains information extracted principally from MEROPS database, filtered, annotated and compared with data stored in other protein and gene public databases, using both automated techniques and domain expert evaluations. The data are organized to allow a flexible and easy way to access stored information. The database is accessible at http://www.plantpis.ba.itb.cnr.it/.     

Complexation as the most important factor in the fate and transport of heavy metals in the Dnieper water bodies

The results of long-term investigations of the concentrations of dissolved forms of some heavy metals (Mn, Cu, Zn, Pb, Cr, Cd) and their species in the water of the Dnieper reservoirs and the Dnieper-Bug estuary are considered. Chemiluminescent methods, anodic stripping voltammetry, membrane filtration, ion-exchange, and gel-permeation chromatography were used for study of the speciation of the metals. It has been found that binding of heavy metals into complexes with dissolved organic matter (DOM) is the dominant factor of their stabilization in solution. The molecular weight distribution of organic metal complexes and their chemical nature, as well as the potential complexing ability of DOM were investigated. Humic substances, particularly fulvic acids, play a major role in the complexation. These ligands bind from 45 to 80% of metals in the form of organic complexes. Metal complex compounds of relatively low molecular weight (<5 kDa) predominated in the organic complexes.