The accumulation of heavy metals in Typha latifolia L. grown in a stream carrying secondary effluent

Typha latifolia L. from aquatic plants is widely found throughout Kehli Stream (Elazig, Turkey). This study examined the uptake of some metals by T. latifolia and the transfer from roots to other plant parts. The accumulation of Mn in T. latifolia L. can be suggested as a tolerance strategy due to its transfer factor higher than 1.0. The enrichment coefficients in the leaves of T. latifolia L. were higher than 1.0 for Zn and Mn and often lower than 1.0 for other metals. Similarly, the enrichment coefficients of all metals, except for Cr, in roots of T. latifolia L. were higher than 1.0. This study demonstrated that T. latifolia L. could be considered as either a bio-indicator or a bio-accumulator for sediments and water polluted by metals.     

Copper exposure reduces production of red carotenoids in a marine copepod

Sub-lethal exposure to copper has been shown to modulate both mitochondrial function and antioxidant gene expression in zooplankton. To date, however, researchers have not identified a quantifiable phenotypic trait that reliably indicates such physiological responses to copper exposure. Red ketocarotenoids are abundant in marine zooplankton serving both physiological and coloration roles, and their production is sensitive to environmental stress. In this study the expression of mitochondrial gene cytochrome c oxidase I (COI) and antioxidant gene glutathione reductase (GR), and the production of red ketocarotenoid, astaxanthin, was measured in response to sub-lethal copper exposure. We found that mRNA of COI and GR was more abundant in copper-exposed copepods than controls, suggesting there was a physiological response to copper exposure. At the same time, copper-exposed copepods produced less astaxanthin than controls. We suggest that ketocarotenoid content of zooplankton has the potential to be a sensitive bioindicator of marine environmental pollution. Understanding how cellular responses to environmental stressors manifest in the phenotypes of marine animals will greatly increase our capacity to monitor marine ecosystem health.     

Heavy metal pollution in surface water and sediment: A preliminary assessment of an urban river in a developing country

The concentration and chemical fractionation of globally alarming six heavy metals (Cr, Ni, Cu, As, Cd and Pb) were measured in surface water and sediment of an urban river in Bangladesh. The decreasing trend of metals were observed in water as Cr > Cu > As > Ni > Pb > Cd and in sediment as Cr > Ni > Cu > Pb > As > Cd. The level of studied metals exceeded the safe limits of drinking water, indicated that water from this river is not safe for drinking and/or cooking purposes. However, the investigated metals showed low mobility except for Cd and Pb which could pose a severe threat to the aquatic environment. Contamination factor (CF) and geoaccumulation index (I_geo) demonstrated that most of the sediment samples were moderately to heavily contaminated by Cr, As, Cd and Pb. The pollution load index (PLI) values were above one (>1) indicates progressive deterioration of the sediment quality. The extent of pollution by heavy metals in the river Korotoa implies that the condition is much frightening to the biota and inhabitants in the vicinity of the river as well.     

Effects of heavy metals on growth and ultrastructure ofChara vulgaris

Summary The toxicity of some heavy metals to the common macrophytic freshwater algaChara vulgaris was studied under laboratory conditions. For experiments, apical tips of algae containing two internodes were cultivated for fourteen days in the presence of various concentrations of cadmium, mercury or lead (as triethyl lead or lead nitrate). Fifty percent growth inhibition occurred with concentrations of 8.5×10^–8 M (9.5 ppb) cadmium, 7.5×10^–7M (150ppb) mercury, 1.6×10^–6 M (330ppb) organic lead or 4× 10^–5 M (8000 ppb) inorganic lead. Sublethal concentrations of these metals caused alterations in the fine structure of internodal cells which turned out to be at least partly metal-specific or in the case of lead, the effects depended on whether the lead was ionic or organically bound. Cadmium and inorganic lead induced disorders of cell wall microfibrils which resulted in local wall protuberances. Mercury affected the chloroplasts which mostly showed considerably increased grana stacks. In addition, mercury caused a dilation of the endoplasmic reticulum and of the mitochondrial tubuli. Organic lead damaged the membrane system of chloroplasts; sheet- or tubule-like thylakoids were disarranged and showed whorl-like structures. At higher concentrations of organic lead, tubular invaginations of the plasmalemma (charasomes) disappeared. The fine structure of nuclei was not altered by any of the metals.     

Optimum utilization of sewage sludge of low and high metal content for grain production on arid lands

Summary Two municipal sludges, one from a highly industrialized city, Chicago, Il, and another from a little industrialized, highly agricultural area, Tucson, AZ are compared for winter barley production on Pima c 1 (Typic torrifluvent). Both sludges were responsible for highly significant additions of Zn, Cu, Ni, Cd and P to the soil each year when applied at the rates of 100 mt/ha singly and 20 mt/ha each year for 4 years. Nitrogen responses for barley straw and grain were observed from both sludges. Tucson sludge appears to be attractive as a potential fertilizer, not only as an NPK source, but also for its organic matter and minimal amounts of heavy metals. The Chicago sludge with relatively high levels of heavy metals, particularly Cd, appears poorly suited as a fertilizer, if used for an extended period of time, because of the plant's tendency to take up elevated levels of certain heavy metals. Some parts of barley plants proved to be a better indicator of heavy metal uptake and concentration than others. The diagnostic-tissue test promises to be a useful tool to warn against undesirable accumulation of heavy metals. Fortunately, when compared with other plant parts, the heavy metal in grain was the least altered as a result of continued sewage sludge use on arid land. The soil's neutral to slightly alkaline pH and the presence of lime throughout the soil profile appeared to be critical factors in keeping plant uptake of heavy metals relatively low as compared with soils of other climates.     

Methylmercury-Induced Elevations in Intrasynaptosomal Zinc Concentrations: An 19F-NMR Study

Abstract: Methylmercury (MeHg) increases the concentration of intracellular Ca²⁺ ([Ca²⁺]_i) and another endogenous polyvalent cation in both synaptosomes and NG108-15 cells. In synaptosomes, the elevation in [Ca²⁺]_i was strictly dependent on extracellular Ca²⁺ (Ca²⁺_e); similarly, in NG108-15 cells, a component of the elevations in [Ca²⁺]_i was Ca²⁺_e dependent. The MeHg-induced elevations in endogenous polyvalent cation concentration were independent of Ca²⁺_e in synaptosomes and NG108-15 cells. The pattern of alterations in fura-2 fluorescence suggested the endogenous polyvalent cation may be Zn²⁺. Using ¹⁹F-NMR spectroscopy of rat cortical synaptosomes loaded with the fluorinated chelator 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N′,N′-tetraacetic acid (5F-BAPTA), we have determined unambiguously that MeHg increases the free intrasynaptosomal Zn²⁺ concentration ([Zn²⁺]_i). In buffer containing 200 µM EGTA to prevent the Ca²⁺_e-dependent elevations in [Ca²⁺]_i, the [Zn²⁺]_i was 1.37 ± 0.20 nM; following a 40-min exposure to MeHg-free buffer [Zn²⁺]_i was 1.88 ± 0.53 nM. Treatment of synaptosomes for 40 min with 125 µM MeHg yielded [Zn²⁺]_i of 2.69 ± 0.55 nM, whereas 250 µM MeHg significantly elevated [Zn²⁺]_i to 3.99 ± 0.68 nM. No Zn²⁺ peak was observed in synaptosomes treated with the cell-permeant heavy metal chelator N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN, 100 µM) following 250 µM MeHg exposure. [Ca²⁺]_i in buffer containing 200 µM EGTA was 338 ± 26 nM and was 370 ± 64 nM following an additional 40-min exposure to MeHg-free buffer. [Ca²⁺]_i was 498 ± 28 or 492 ± 53 nM during a 40-min exposure to 125 or 250 µM MeHg, respectively. None of the values of [Ca²⁺]_i differed significantly from either pretreatment levels or buffer-treated controls.     

The ecological significance of nickel hyperaccumulation: a plant chemical defense

Nickel hyperaccumulating plants have more than 1000 mg Ni kg^–1 dry weight when grown on nickel-bearing soils. We hypothesized that Ni hyperaccumulation could serve as a chemical defense against herbivores In feeding experiments with potential insect herbivores and Ni hyperaccumulating plants, only those inseets fed leaves from plants grown on non-nickel-bearing soil survived or showed a weight gain. Among chemical parameters measured, only Ni content of plants was sufficient to explain this result. When subjected to herbivory by lepidopteran larvae, plants grown on Ni-amended soil showed greater survival and yield than plants on unamended soil. Ni hyperaccumulation may be an effective plant chemical defense against herbivores because of its high lethality, apparent low cost, and broad spectrum of toxicity.     

Soil factors affecting patchiness in community composition of heavy metal-contaminated areas of Western Europe

The vegetation at various sites within two separate areas (Mechernich and Aachen) of the Eifel Mountains, Germany/Belgium, both characterized by elevated concentrations of heavy metals in their soils, was surveyed in order to investigate the relationships between soil chemical attributes and floristic composition. In both areas, the typical heavy metal communities can form distinct zones, clearly separated from the surrounding heavy metal-sensitive vegetation. However, an intergrading of heavy metal-tolerant and-sensitive vegetation types is not uncommon and such overlaps can occupy large areas. In Mechernich, soil toxicity is primarily determined by the effects of lead, which is best expressed in terms of the Pb/Ca ratio rather than the absolute levels of this metal in the soil. Soils of heavy metal-sensitive vegetation types have a low Pb/Ca ratio, whereas it is considerably higher in areas supporting heavy metal vegetation. Zinc appears to exert little influence on the floristic composition of the investigated vegetation types. In Aachen, zinc is the predominant heavy metal determining vegetation development. Absolute zinc levels of soils do not accurately reflect zinc toxicity. Analogous to the role of the Pb/Ca ratio in the Mechernich area, the Zn/Ca ratio not only separates heavy metal-sensitive and highly tolerant vegetation units, but also gives a good indication of the gradient operating between the two vegetation types. Lead is probably only of local importance in influencing species composition.     

应用重离子束苏制核微孔滤膜除菌除支原体的研究

本文采用苏制核微孔滤膜进行了除菌、除支原体实验研究,核孔膜孔径分别为０．０７、０．１、０．５、０．７及１．５微米,采用的菌种为白色葡萄球菌、链球菌和大肠杆菌,支原体为解脲脲原体,实验结果表明：０．０７及０．１微米的核孔膜可完全滤除细菌及支原体,０．５微米的核孔膜可滤除绝大部分细菌,不能滤除支原体,１．５微米的核孔膜只能滤除少量细菌。     

Incidence of heavy metals in the mangrove flora and sediments in Kerala, India

The mangroves of Kerala on the south-west coast of India are fast disappearing due to land reclamation and other anthropogenic disturbances. There are very few ecosystem level studies made in these much threatened biotopes in Kerala. The present study involves the measurement of heavy metals in the mangrove flora and sediments of three mangrove habitats along the Kerala coast. Sampling was carried out for a period of one year at bi-monthly intervals, with concentrations of Fe, Mn, Cu,Zn,Pb and Co analysed using atomic absorption spectrophotometry. An appreciable variation was observed in metal concentrations indifferent mangrove species. Cu, Zn and Pb were found to be in higher concentrations in Avicennia officinalis whereas higher levels of Fe, Mn and Co were observed in the species Barringtonia racemosa. The analysis of heavy metals indicated a high level of metal pollutants such as Fe, Cu, Zn and Pb in the mangrove habitats of Quilon and Veli compared to the relatively uncontaminated areas of Kumarakom. This revised version was published online in August 2006 with corrections to the Cover Date.