Phytoaccumulation of heavy metals by aquatic plants

Three aquatic plants were examined for their ability to remove heavy metals from contaminated water: parrot feather (Myriophylhum aquaticum), creeping primrose (Ludwigina palustris), and water mint (Mentha aquatic). The plants were obtained from a Solar Aquatic System treating municipal wastewater. All the three plants were able to remove Fe, Zn, Cu, and Hg from the contaminated water. The average removal efficiency for the three plant species was 99.8%, 76.7%, 41.62%, and 33.9% of Hg, Fe, Cu, and Zn, respectively. The removal rates of zinc and copper were constant (0.48 mg/l/day for Zn and 0.11 mg/l/day for Cu), whereas those of iron and mercury were dependent on the concentration of these elements in the contaminated water and ranged from 7.00 to 0.41 mg/l/day for Fe and 0.0787 to 0.0002 mg/l/day for Hg. Parrot feather showed greater tolerance to toxicity followed by water mint and creeping primrose. The growth of creeping primrose was significantly affected by heavy metal toxicity. The selectivity of heavy metals for the three plant species was the same (Hg>Fe>Cu>Zn). The mass balance preformed on the system showed that about 60.45-82.61% of the zinc and 38.96-60.75% of the copper were removed by precipitation as zinc phosphate and copper phosphate, respectively.     

铜绿微囊藻对有机毒物菲的生理生态响应研究

选取富营养化湖泊蓝藻水华常见优势种铜绿微囊藻（Microcystis aeruginosa,M. aeruginosa）为研究对象,采用室内暴露培养实验考察多环芳烃（Polycyclic aromatic hydrocarbons,PAHs）化合物菲（Phenanthrene,Phe）对铜绿微囊藻生长及生理特性的影响效应和作用机制。研究结果表明,低浓度Phe（0.05~0.2 mg/L）对铜绿微囊藻细胞生长有不同程度的促进作用,0.2 mg/LPhe促进作用最为显著（P＜0.05）;高浓度Phe（0.5~1.0 mg/L）显著抑制铜绿微囊藻生长（P＜0.05）。铜绿微囊藻典型生理指标细胞光合作用率（Fv/Fm）、超氧化物歧化酶（SOD）、谷氨酰胺还原酶（GR）酶活性以及丙二醛（MDA）含量同步分析结果显示,低浓度Phe通过增强SOD、GR酶活性,降低铜绿微囊藻细胞内MDA含量,提高藻细胞光合作用率,进而促进细胞增殖;高浓度Phe则通过降低SOD、GR酶活性,增加藻细胞内MDA产量,减弱细胞光合作用,从而抑制细胞生长。对不同暴露时刻藻细胞的生长抑制率进行回归分析可得EC50（半抑制浓度）随着污染暴露时间增加而减低,1day EC50为1.27 mg/L,12day EC50降至0.65 mg/L,即高剂量Phe（0.5~1.0 mg/L）对微囊藻细胞生长的抑制作用随时间延长逐渐增强。结合低剂量浓度下Phe对铜〖JP+2〗绿微囊藻生长的促进作用分析,湖泊生态系统Phe污染长期暴露对铜绿微囊藻生长生理特性及优势种的形成和维持具有不可忽视的作用。其中,铜绿微囊藻细胞主要生理指标SOD与GR对Phe污染胁迫反应灵敏,可用作评价PAHs等有机毒物对浮游藻类生理生态影响的生物标记物     

The Response of Hydrophytes to Environmental Pollution with Heavy Metals

The effects of Cu²⁺, Cd²⁺, and Ni²⁺ at low and high concentrations (0.025 and 0.25 mg/ml) on the accumulation capacity, the state of the pigment complex, and photosynthesis rate have been studied in model experiments with three floating hydrophytes (Hydrocharis morsus-ranae L., Lemna gibba L., and Potamogeton natans L.) and four submerged hydrophytes (Elodea canadensis Michx., Lemna trisulka L., Ceratophyllum demersum L., and Potamogeton lucens L.). Copper and cadmium are especially toxic at the concentrations studied. The effect of Cu²⁺ was the strongest in hydatophytes, and the effect of Cd²⁺, in pleustophytes. It is hypothesized that the differences between hydrophytes with respect to accumulation of metals and decrease in photosynthesis rate may cause predominant elimination of submerged species. Therefore, changes in the species structure of hydrophyte communities may be expected in waters polluted with metals.     

Effect of boric acid on the ability of plants to accumulate heavy metals

The effect of boric acid on the ability of herbaceous plants to absorb heavy metals has been studied. The results show that at a low content of boron in sandy loam soil (0.0007 mg/kg dry matter), boric acid at doses of 0.1–3.0 kg/ha stimulates the accumulation of certain heavy metals in the aboveground part of plants from the families Asteraceae (Taraxacum officinale Wigg.), Poaceae (Phleum pratense L.), and Fabaceae (Trifolium pratense L.). The most active accumulation is characteristic of dandelion (T. officinale) plants, which allows this species to be considered promising for phytoremediation of soils with a low boron content given that boron is applied at specified doses.     

Features of Prooxidant and Antioxidant Systems of Greater Plantain <Emphasis Type="Italic">Plantago major</Emphasis> Growing for a Long Time under Conditions of Radioactive Contamination

The viability and state of the prooxidant and antioxidant systems of Plantago major seed progeny from cenopopulations growing for a long time at the East-Ural Radioactive Trace (EURT) has been estimated. Radiation doses of maternal plants have been calculated using our empirical data in ERICA Tool. The absorbed dose rates for plantain in the EURT zone varied from 19 to 157 μGy/h, which is 178–1455 times higher than the background values. These relatively low levels of chronic irradiation did not cause a significant decrease in the survival rate of P. major seed progeny; the rate of root and leaf growth decreased only in seedlings from the most polluted cenopopulation. A prooxidant shift was revealed in seedlings from the EURT zone. Given the same regime of enzyme protection (SOD, CAT, and POX) against active oxygen forms, the average rate of accumulation of secondary products of lipid peroxidation (MDA) was 3.3 times higher in impact samples than in background samples. The level of prooxidant shift in impact samples is not linearly related to dose rates that are classified as low doses.     

Effects of natural and chemical stressors on Enchytraeus albidus: Can oxidative stress parameters be used as fast screening tools for the assessment of different stress impacts in soils?

Enchytraeids are important organisms of the soil biocenosis. They improve the soil pore structure and the degradation of organic matter. These organisms are used in standardized testing, using survival and reproduction (6 weeks) as endpoints. The use of biomarkers, linked to ecologically relevant alterations at higher levels of biological organization, is a promising tool for Environmental Risk Assessment. Here, enchytraeids were exposed for different time periods (two days and three weeks) to different soils (OECD artificial soil, different compositions in its organic matter, clay or pH value, and LUFA 2.2 natural soil) and different chemicals (Phenmedipham and copper). The main question addressed in the present study was if the effects of chemicals and different soil properties are preceded by alterations at the sub-cellular level, and if these endpoints may be used reliantly as faster screening tools for the assessment of different stress conditions in soils. The parameters measured in E. albidus whole body were: lipid peroxidation (LPO), total glutathione (TG), as well as the enzymatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione S-transferase (GST). The results showed that biomarker responses in E. albidus were significantly affected by the soil type (GST, CAT, GPx, GR and LPO) and the duration of exposure in OECD artificial soil (GST, GPx, GR, CAT and LPO) but not in LUFA 2.2 natural soil. For the abiotic factors studied, after 2 days, low pH decreased significantly the TG levels and the activities of CAT and GR,and low OM also significantly decreased CAT and GR activities. After 3 weeks, differences in soil properties caused a decrease in GR and GPx activities, whereas increased GST activity was observed due to low organic matter and pH. Copper significantly increased the activities of CAT, GPx and GR, and decreased the activity of GST after 2 days as well as inscreasing LPO levels after 3 weeks. Phenmedipham increased LPO levels, associated with increased levels of TG as well as increased activities of CAT and GPx and decreased GST activity after 3 weeks exposure. This study shows that both abiotic and chemical stresses could be followed through biomarker analysis and that some of these determinations are potential endpoints in a quick soil contamination assessment procedure.     

Assessment of biological effects in <Emphasis Type="Italic">Plantago major</Emphasis> L. Seed progeny in the zone of impact from a Copper Smelter

The quality of seed progeny was studied in Plantago major from populations growing for a long time in the gradient of chemical pollution around the Karabash Copper Smelter (KCS). The results showed that the range of variation in seed germination and seedling survival rates was wider in background than in impact populations. The lowest values of growth parameters (the number of seedlings with a true leaf and root length) were recorded in the sample from the most polluted plot. Challenging exposure to toxic elements (seed germination in soils from polluted plots) was found to stimulate, to different extents, the rate of leaf formation and suppress root growth in the seedlings. It cannot be stated from these results that the adaptive potential of plants grown in the zone of impact from the KCS is altered, compared to that in other samples. Evaluation of the prooxidant and antioxidant status of seedlings from this zone revealed a decrease in superoxide dismutase and catalase activities (to 60 and 33% of background values, respectively) and an increase in peroxidase activity (to 122%). The prooxidant status of seedlings in samples from the KCS zone was found to be increased, except for the sample from the most polluted plot.     

The role of arsenate reductase and superoxide dismutase in As accumulation in four Pteris species

Using arsenic (As) hyperaccumulators to extract As from contaminated soils is an effective and low-cost technology. Most of the known As hyperaccumulators belong to Pteris species. The present study aims to explore the responses and role of arsenate reductase (AR) and superoxide dismutase (SOD) in As hyperaccumulating fern species (Pteris vittata, and P. multifida) and non-As hyperaccumulating species (P. ensiformis, and P. semipinnata) when grown in soils added with 0 (control), 100, and 200 mg/kg (dry weight) of arsenic as Na(2)HAsO(4).7H(2)O. The results show that AR activities of roots, SOD activities and As concentrations in both roots and fronds of the four Pteris plants increased when exposed to As-contaminated soils. AR activities of roots were much higher, but SOD activities and As concentrations of roots were lower than those of fronds. It is concluded that AR of roots and SOD of both roots and fronds may play important roles to accumulate and detoxify As in the four Pteris species.     

Seasonal variation in photosynthesis in relation to differing environmental factors of dominant plant species in three successional communities in Hangzhou Bay Wetlands,East China

We investigated the ecophysiology (physiological ecology) of plant succession within a coastal wetland community. The photosynthetic characteristics of six plants were studied; Scirpus mariqueter and Carex scabrifolia in early successional communities, Phragmites communis and Tamarix chinensis in mid successional communities, and Salix matsudana and Imperata cylindrica in later successional communities. Environmental factors were concurrently determined for each community. Relationships between photosynthetic and environmental factors were analyzed by path analysis, and the dependence of photosynthesis on particular environmental factors was shown to vary between plants in the differing successional communities. Ability to cope with irradiation appears to be one of the most important factors influencing plant succession. The increasing stratification of plant communities following colonization of new coastal land necessitates differing physiological strategies and photosynthetic dynamics in the later colonizing plants.     

Toxicity of copper in sewage sludge

Sewage sludge is a source of organic matter and nutrients, but a major obstacle for its recycling is that the municipal wastewater sludge has low but significant levels of contaminants. This investigation, on the acute toxicity of copper in sewage sludge, was conducted with three organisms, Daphnia magna, Lemna minor and Raphanus sativus (seeds). The toxicity of the leakage water from sewage sludge spiked with CuSO(4) was studied for 64 days. The toxicity increased during the first 8-16 days and then started to decrease. The first increase in toxicity was due to ammonia, but after 32 days, a dose-related effect of copper was found. After 64 days, L. minor had an EC50 of 3800 mg Cu/kg dw for 7 days growth inhibition, a LOEC of 3200 mg Cu/kg dw and a NOEC of 1600 mg Cu/kg dw. D. magna had an EC50 of 18100 mg Cu/kg dw (24-h immobility) and a NOEC of 12800 mg Cu/kg dw. Root elongation of R. sativus was reduced at 25600 mg Cu/kg dw. Both for Daphnia and Lemna, the pH of the leakage water had an effect of the toxicity. This means that chemical speciation and bioavailability is very important for the hazard assessment of copper in sludge and soil.     

Growth response of Scenedesmus to different concentrations of copper, cadmium, nickel, zinc, and lead

The fresh water alga Scenedesmus was cultured in graded concentration of Cu, Cd, Ni, Zn, and Pb to evaluate the effect of these cations on the growth response of Scenedesmus. The effective concentration of metal which depressed the Scenedesmus growth for Cu was 0.5 mg l⁻¹, for Cd 0.5 mg l⁻¹, for Ni 2 mg l⁻¹, and for Zn 2 mg l⁻¹. The alga exhibited tolerance for high Pb concentrations up to 30 mg l⁻¹. Exposure of a Scenedesmus cell to each metal revealed anatomical changes and chloroplast disruption especially at high metal concentrations.     

Complex toxic effects of Cd2+, Zn2+, and acid rain on growth of kidney bean (Phaseolus vulgaris L)

Complex toxic effects of Cd2+, Zn2+, and acid rain on growth of kidney bean (Phaseolus vulgaris L) were studied in a pot experiment by measurement of fresh weights of the plants, determination of surperoxide dismutase (SOD), peroxidase (POD), and lipid peroxidation (MDA) in the plant organs, and observation of injury symptoms. The experimental results demonstrated that all treatments of Cd2+, Zn2+, and/or acid rain significantly decreased fresh weights of kidney bean and caused toxic effects on growth of the plants, especially higher amounts of Cd2+ and Zn2+ and higher acidity of acid rain. Combination of these three pollutant factors resulted in more serious toxic effects than any single pollutant and than combinations of any two pollutants. SOD, POD, and MDA in the plant organs changed with different pollution levels, but MDA content in the leaves showed the best relationship between the pollution levels and toxic effects.     

Effect of copper-tolerant rhizosphere bacteria on mobility of copper in soil and copper accumulation by Elsholtzia splendens

The role of rhizosphere bacteria in facilitating the solubility of copper (Cu) in contaminated soil and Cu accumulation in plant were studied. The bacteria strains were isolated from the rhizosphere of Elsholtzia splendens, a Cu accumulator growing on Tonglu Mountain copper mines. After the sandy soils containing 237 mg kg(-1) were incubated with the bacteria strains, it was indicated that rhizosphere microbes played an important role in influencing the availability of water-soluble Cu in soils. Soils had greater concentrations of water-extractable Cu compared with axenic soils inoculated with different bacterial strains. Further evidence for bacterial facilitation of increased solubility of Cu in the soil was obtained using the antibiotic ampicillin (0.1 mg g(-1)). There were 36% decreases in Cu concentration in the presence of bacterial strain MS12 and ampicillin together compared with bacterial inoculation alone. Different bacterial strains had different abilities on soil water-soluble Cu. To achieve the highest rates of plant Cu accumulation, it was necessary for bacteria to be present in the rhizosphere of E. splendens. Inoculated plants supplied with 20 micromol L(-1) CuSO4 had significantly greater concentrations of Cu in shoots and roots than uninoculated plants and bacterial strain MS2 was the most effective strain in promoting plant Cu uptake. There were 2.2-fold and 2.5-fold increases in Cu accumulation in the shoots and roots of plants inoculated with strain MS2 compared to axenic controls. Furthermore, when ampicillin and the bacterial strains were added together to the nutrient solution, the Cu concentrations in roots and shoots of ampicillin-treated plants were lower than those in inoculated plants. When ampicillin was added to the nutrient solution, Cu accumulation was inhibited by about 24-44% in shoots and 20-44% in roots. The above results provided a new insight into the phytoremediation of Cu-contaminated soil.     

Strategies of adaptation to heavy metal pollution in Deschampsia caespitosa and Lychnis flos-cuculi: Analysis based on dose-response relationship

The response to copper pollution was studied in the vegetative progeny of tufted hair grass (Deschampsia caespitosa (L.) Beauv.) and ragged robin (Lychnis flos-cuculi L.) plants growing together in chronically polluted areas around the Middle Ural Copper Smelter or in background areas. The root elongation test was used, with copper sulfate (0.006–0.51 mg Cu/L) being added directly to the nutrient medium. Using multimodel inference, dose-response curves were plotted for each of 85 maternal plants, and their parameters (effective Cu concentrations and curve slope in the linear segment) were evaluated. The pattern of transformation in dose dependence of root increment upon transition from background to impact populations proved to be basically different in the two species. The curves for L. flos-cuculi showed a parallel shift, with their shape remaining generally unchanged. In D. caespitosa, this transition was accompanied by a decrease in sensitivity to Cu, but tolerance to this metal was found to increase only at the highest concentration range. These results provide evidence for different strategies of adaptation to heavy metal pollution, which are discussed by comparing the physiological and ecological properties of the two species.     

Halotolerant bacteria of the genus <Emphasis Type="Italic">Arthrobacter</Emphasis> degrading polycyclic aromatic hydrocarbons

Eight strains of bacteria capable of degrading polycyclic aromatic hydrocarbons have been isolated from soils and bottom sediments sampled in the region of Verkhnekamskoe potash deposit (Berezniki, Perm krai) and classified with the genus Arthrobacter on the basis of phylogenetic analysis (16S rRNA genes) and morphological and chemotaxonomic characters. According to the results of 16S rDNA sequence alignment, strains B905, SMB11, SMB145, SF27, and DF14 show the highest sequence homology to the type strain of A. crystallopoietes (99.7%), and strain SN17, to the type strain of A. arilaitensis (99.8%). The isolated strains are capable of growing on naphthalene and phenanthrene (as the sole sources of carbon and energy) in the presence of 60 mg/l NaCl. Their cells contain large plasmids ranging in size from 85 to 130 kb. Plasmid elimination from Arthrobacter sp. SF27 has proved to result in the loss of capacity for growing on naphthalene and phenanthrene, suggesting a plasmid localization of genes responsible for degradation of these compounds.     

Fly ash leachate induces oxidative stress in freshwater fish Channa punctata (Bloch)

Oxidative stress inducing potential of fly ash leachate (FAL) was studied in a freshwater fish, Channa punctata (Bloch). Fish were exposed to fly ash leachate for 24 h and lipid peroxidation (LPO) was studied as a marker of oxidative stress. Catalase (CAT), glutathione S-transferase (GST) activities and levels of reduced glutathione (GSH) were also estimated in the exposed fish. FAL (1 ml/l) induced LPO in all the organs and most prominent response was in the gill. It also caused induction of enzymes and glutathione. Liver showed highest level of induction of enzyme activities. The results of this study demonstrate that fly ash constituents have potential to induce oxidative stress in fish and gills are the most vulnerable organs. It is also suggested that in case of exposure to FAL, along with LPO antioxidant defense is also activated to counteract the reactive oxygen species (ROS) at least partly in the initial stages of exposure.     

Lipid peroxidation rates in <Emphasis Type="Italic">Taraxacum officinale</Emphasis> Wigg. and <Emphasis Type="Italic">Vicia cracca</Emphasis> L. from biotopes with different levels of soil pollution with heavy metals

The rates of lipid peroxidation (LPO) have been studied in Taraxacum officinale Wigg. (Asteraceae) and Vicia cracca L. (Fabaceae) from urban ecosystems with different levels of soil pollution with heavy metals (HMs), including Pb, Zn, Cu, and Cr. The former species responds to the increased HM contents by intensification of LPO processes, with their parameters correlating with the concentrations of Pb, Zn, and Cu in the soil. In the latter species from the same biotopes, conversely, LPO homeostasis remains actually undisturbed.     

Characterization of natural organic matter from eight Norwegian surface waters: Proton and copper binding

As a part of the International NOM-Typing Project, proton and copper binding studies were conducted on ultrafiltered (>1000 dal.) and dialysed (>100 dal.) natural organic matter (NOM) samples from eight Norwegian Lakes. The NOM samples were similar with respect to proton and copper binding, although minor differences were observed among the samples of different origin. Slight variations occurred for seasonal changes and lime additions. The proton binding pK_a values grouped in three distinct classes: pK_a1 = 4.20–4.28; pK_a2 = 6.61–6.87; and pK_a3 = 9.27–9.8. The average total proton binding site concentration of the NOM samples was: 12.7 meq/g total organic carbon (TOC). Two binding sites were established for copper with average log K1 = 4.84 and log K2 = 7.17. The average site concentration for samples isolated by reverse osmosis (RO) was 0.56 μmol/mg C. Copper binding characteristics appear to be influenced by the method of sample isolation. For NOM isolated by low pressure evaporation (evap), binding site concentrations are smaller, conditional stability constants are higher, variability of the copper complexation capacity is smaller, and correlation with elemental composition (C, N, H) is better than in the case of NOM isolated by RO.     

Distribution of herbaceous plants around nests of <Emphasis Type="Italic">Formica aquilonia</Emphasis> Yarr. in a fragmented forest area

Topical connections between F. aquilonia ants and herbaceous plants in a fragmented forest area have been analyzed. The species composition of the group of herbaceous plants changing their occurrence frequency in response to the presence of F. aquilonia nests has been determined. Ecological and phytocenotic parameters of herbaceous plants contributing to the development of the myrmecotopic assemblage are described. Signs of meadowfication and synanthropization of the herbaceous layer around ant nests have been observed.     

Biotopic Variation and Phenogeography of Dreissena polymorpha (Pallas)

The phenetic structure of Dreissena polymorpha populations in different water bodies is considered. The phenotypes of shell pattern and sculpture are identified and described using a scheme based on elementary characters, or pattern elements. It is shown that the frequencies of phenes in mollusks from different biotopes of the cooling system of two thermal power plants differ significantly. The data on species phenogeography are reviewed.