Geochemical partitioning and bioavailability of copper to aquatic plants in an artificial oxide-organic sediment

This study investigated the effects of competition between binding substrates (organic matter and iron oxide) and between metals (cadmium and copper), on the partitioning of sedimentary copper and its subsequent bioavailability to an aquatic plant. Organic matter and a synthesized iron oxide, ferrihydrite, were added singly and in combination to a series of sand sediments, which were then dosed with environmentally realistic concentrations of cadmium and copper and planted with rice,Oryza sativa. Organic matter controlled copper partitioning and bioavailability, whereas the synthetic ferrihydrite bound negligible amounts of either metal, even in the absence of organic matter. As organic matter concentrations increased, operationally-defined leachable copper decreased, organic-associated copper increased and the survival of rice plants improved in an approximately linear fashion. At a nominal starting copper concentration of 5.8 μg g dry wt⁻¹, plant survival after four weeks averaged 0–8% in sediments without organic matter, 25% in a sediment containing 0.18% organic matter and 58% in a sediment containing 0.36% organic matter. These results suggest that organic-associated forms of copper are unavailable to plants, and that the operational definition of ‘leachable’ copper (extracted with dilute ammonium acetate) adequately represents the species of copper that is (are) available to plants. Our study using a well-characterized artificial sediment supports the copper fractionation patterns and correlations between copper partitioning and bioavailability reported from the heterogeneous, poorly characterized sediments of natural lake and river sediments.     

植物铜转运相关蛋白研究进展

环境中过量的铜会损害植物细胞的功能、降低酶的活性并且破坏蛋白质的结构。植物中有一个复杂的金属转运网络,对维持植物体内铜的动态平衡发挥着重要作用。综述了重金属铜对植物的毒害,详细介绍了铜转运相关蛋白及其对铜的转运和调控机制。     

Genes involved in copper resistance influence survival of Pseudomonas aeruginosa on copper surfaces

Aims:  To evaluate the killing of Pseudomonas aeruginosa PAO1 on copper cast alloys and the influence of genes on survival on copper containing medium and surfaces.
Methods and Results:  Different strains of P. aeruginosa were inoculated on copper containing medium or different copper cast alloys and the survival rate determined. The survival rates were compared with rates on copper-free medium and stainless steel as control. In addition, the effect of temperature on survival was examined.
Conclusions:  Copper cast alloys had been previously shown to be bactericidal to various bacteria, but the mechanism of copper-mediated killing is still not known. In this report, we demonstrate that P. aeruginosa PAO1 is rapidly killed on different copper cast alloys and that genes involved in conferring copper resistance in copper-containing medium also influenced survival on copper cast alloys. We also show that the rate of killing is influenced by temperature.
Significance and Impact of the Study:  To use copper surfaces more widely as bactericidal agents in various settings, it is important to understand how genes influence survival on these surfaces. Here we show that genes shown to be involved in copper resistance in P. aeruginosa PAO1 can have an impact on the length of survival time on copper cast alloys under certain conditions. This is an important first step for evaluation of future use of copper surfaces as bactericidal agents.     

Accumulation of copper and zinc from liquid manure in agricultural soils and crop plants

In Northern Italy it is a common practice to utilise slurries and other manure from intensive animal farming to fertilise agricultural soils. Due to the relatively high copper and zinc contents of these materials, this practice could lead to contamination of soils and the crops grown on them. In this study we have evaluated the extent of copper and zinc contamination of soils subjected to different levels of fertilisation with liquid manure and the copper and zinc concentrations in the edible tissues of three crops (maize, sugar beet and lucerne) grown on the same soils. There was a direct correlation between soil copper and zinc contents and the levels of application of animal wastes and copper concentrations were high enough to represent a risk, according to current European legislation. The metal contents in the edible tissues of the three crops were relatively low and variable, but showed no clear correlations with the intensity of liquid manure applications. Overall, there was no risk of contamination of the food chain, as all concentrations were well below levels considered to be toxic to animals.     

Reevaluating the free-ion activity model of trace metal availability to higher plants

The plant uptake and toxicity of many metals show a marked dependence on the aqueous speciation of the metal, and these responses often correlate best with the activity of the free metal ion. Exceptions to this generalization have been observed, however, and we sought to critically reexamine the theoretical foundation of the free-ion activity model (FIAM) of metal bioavailability to higher plants. Binding by an apoplastic functional group is often envisioned as a requisite step in the absorption or toxicity of a metal, and can be modeled in a variety of ways. Typically, however, speciation of the bulk solution is calculated without regard to such surface binding, even though it could influence the pertinent mass balance expressions. A more thorough treatment considers simultaneous formation of both the metal-ligand complex in solution (ML) and the metal-cell surface complex (M-X). Here, empirical conformity to the FIAM can be expected, but only under pivotal assumptions about the relative sizes of the test solution and the root biomass, and about the relative binding strength of L and -X. Moreover, empirical conformity to the FIAM does not preclude cell-surface binding of the complexed metal followed by ligand exchange (ML + -X M-X + L), so that correlations between biological response and free metal-ion activity imply nothing about the molecular species that actually interacts with the cell surface. Computer simulations of Cu (II) binding by a model apoplastic ligand are used to illustrate these and other key features of the FIAM. Departures from the FIAM seem most likely when (i) the quantity of the metal-complexing ligand is limited (as may be the case in soil solution or in the rhizosphere), and/or (ii) the solution ligand is very weak.     

An assessment of the early stages of microfouling and corrosion of 70:30 copper nickel alloy in the presence of two marine bacteria

The early stages of bacterial settlement on 70:30 copper nickel alloy was followed by scanning electron microsocopy. Two strains of marine bacteria (Pseudomonas sp and Vibrio alginolyticus) isolated from polluted harbour sea water were used. The corrosion behaviour of the alloy was studied through corrosion potential measurements made in sterile and contaminated sea water. According to our results microbial colonisation of the metal surface occurs within the first 24 h for the two bacteria used. Well defined microbial colonies with localised corrosion underneath were seen by SEM after short periods of exposure. Corrosion attack seems to be closely related to passive film modification by the bacterial settlement.     

The complexation of aqueous metal ions relevant to biological applications. 2. Reactions of copper(II) citrate and copper(II) succinate with selected amino acids

Abstract

Addition of amino acids, glycine, alanine, and serine, to poorly soluble copper(II) salts [copper(II) citrate and copper(II) succinate] all increase solubility of the copper(II) salts. Relative increases in solubility follow the polarity trend in the selected amino acids, with serine creating the greatest increase in solubility. Simultaneous equilibria calculations indicate the formation of mixed-ligand complexes in the copper(II) succinate–amino acid systems, the first time such mixed-ligand complexes have been observed. In contrast, mixed-ligand complexes are not predicted in the copper(II) citrate–amino acid systems. Potential bioavailability of copper(II) appears to be increased by the inclusion of amino acids in solution, roughly in parallel with the increase in solubility of the copper(II) salt. Therefore, measurement of the change in solubility caused by addition of amino acids to aqueous solution gives qualitative insight to the potential increase in bioavailability of the metal ion.     

Determination of copper, manganese and zinc in human liver

Autopsied liver tissue samples collected from 42 males and 31 females were analyzed for copper, manganese and zinc using atomic absorption spectrometry (AAS). With the exception of two liver samples for which the copper levels were determined to be 74.8 and 104.0 g/g (dry weight), hepatic copper concentrations were found to range from 1.7 to 32.4 g/g with a mean concentration of 14.2 g/g and standard deviation of 7.0 g/g. Manganese concentrations (with the exception of one sample having 12.9 g/g) ranged from 0.22 to 4.6 g/g with a mean of 2.26 ± 1.00 g/g. Hepatic zinc levels averaged 118.3 ± 44.4 g/g and ranged from 38.5 to 231.3 g/g. There were no apparent trends for the levels of any metals versus age nor were there any differences in average hepatic metal concentrations for males and females. © Rapid Science 1998.     

Life cycle contributions of copper from vessel painting and maintenance activities

Copper-based epoxy and ablative antifouling painted panels were exposed in natural seawater to evaluate environmental loading parameters. In situ loading factors including initial exposure, passive leaching, and surface refreshment were measured utilizing two protocols developed by the US Navy: the dome method and the in-water hull cleaning sampling method. Cleaning techniques investigated included a soft-pile carpet and a medium duty 3M^? pad for fouling removal. Results show that the passive leach rates of copper peaked three days after both initial deployment and cleaning events (CEs), followed by a rapid decrease over about 15 days and a slow approach to asymptotic levels on approximately day 30. Additionally, copper was more bioavailable during a CE in comparison to the passive leaching that immediately followed. A paint life cycle model quantifying annual copper loading estimates for each paint and cleaning method based on a three-year cycle of painting, episodic cleaning, and passive leaching is presented.     

鱼体(去鳃)和鱼鳃对不同形态铜的积累特征

在实验室条件下研究实验鱼Ｐａｒａｃｈｅｉｒｏｄｏｎ对人工河水中不同形态的积累特征,对比了鱼体（去鳃）和鱼鳃对铜吸收量的差异,并探讨了鱼对铜的吸收机理。研究结果表明,实验鱼鳃部和体内铜积累量均随水相游离铜浓度增高,暴露时间增长而增加,但鳃部积累浓度较鱼体其余部分高一个数量级,其从水相富集铜的速率显著高于鱼体。     

Influence of breed on blood and tissue copper status in growing and finishing steers fed diets supplemented with copper

To evaluate the influence of breed on the accumulation of dietary copper (Cu) in tissue, and on blood parameters indicative of Cu status, ten Galician Blond, nine Holstein-Friesian and ten Galician Blond × Holstein-Friesian cross (GB × HF) steers were fed diets supplemented with 35 mg/kg DM of CuSO₄ during their growing and finishing periods. Blood samples were taken monthly, and samples of liver, kidney, brain, heart, spleen and muscle were taken at slaughter. Cu concentrations were determined by ICP-AES. Holstein-Friesian calves had significantly higher total liver Cu contents than Galician Blonds and GB × HF crosses (mean 1070, 663 and 868 mg, respectively), combined with higher hepatic Cu concentrations (174, 140 and 166 mg/kg wet weight, respectively). Holstein-Friesian calves had also the highest prevalence (89%) of hepatic Cu concentrations exceeding the toxic limit of 150 mg/kg wet weight. Breed did not have a statistically significant influence on blood parameters. With the exception of the semitendinosus muscle, where Holstein-Friesians (0.790 mg/kg) had significantly higher Cu levels than Galician Blonds (0.541 mg/kg) or GB × HF crosses (0.631 mg/kg), no other statistically significant differences by breed in the extrahepatic tissue Cu distribution were observed. A negative statistical association between carcass performance and the ratio of semitendinosus and liver Cu concentration could indicate that the animals with a better carcass performance (Galician Blonds) could need a higher Cu mobilisation into the muscle, resulting in a lower hepatic storage.     

Phosphate limitation influences the sensitivity to copper in periphytic algae

1. To assess the influence of nutrient limitation on copper toxicity, periphitic communities from an oligotrophic stream were exposed to copper for six to 12 days with and without the supply of nutrients (mainly P). 2. In contrast to the hypothesis that nutrient cycling in mature biofilms would protect them from Cu toxicity, low and high biomass biofilms did not differ in their physiological response to copper after 6 days of exposure. 3. A clear influence of P‐limitation on copper toxicity was observed. Periphytic communities that were previously fertilised for 18 days were three times more tolerant than control communities indicating that P‐limitation enhanced Cu toxicity and tolerance induction were probably related to the higher P‐availability. In addition, a compensation of Cu toxicity after P‐addition was observed in the long‐term (after 12 days). 4. We conclude that periphyton from oligotrophic streams is more sensitive to copper than periphyton from fertilised streams, and that therefore a higher effect of chronic copper exposure is expected to occur in oligotrophic P‐limited fluvial systems. 5. Extrapolation of our results to the area of study (Catalonia, north‐east of Spain) indicates that while the levels of Cu commonly found in the zone may negatively affect the periphyton from oligotrophic streams, because of the interaction between Cu and P, they are not able to control the growth of nuisance algae which is common under high nutrient conditions.     

Response of shape in vitro cultures of shape Nicotiana tabacum L. to copper stress and selection of plants from Cu-tolerant callus

In Nicotiana tabacum L. var. BEL W3 copper (Cu) at concentrations higher than 50 μM significantly inhibited callus growth and shoot regeneration. After 5–6 months of culture only a few morphogenic callus lines survived in the presence of 100 μM Cu. These calluses showed the capacity to grow and regenerate shoots through successive subcultures on medium containing 100 μM Cu. The 100 μM Cu-tolerant shoots, in comparison to regenerated control shoots, formed roots only when cultured in the presence of 100 μM Cu. From five independent Cu-tolerant callus lines in a culture period of 4–5 months more than 50 plants (defined ‘tolerant’) able to grow in presence of 100 μM Cu were obtained. These plants showed normal xylem tissue formation while control regenerated plants growing in normal Cu MS content (0.1 μM) had few xylem elements in the central cylinder. No difference as far chlorophyll content and chloroplast structure was found among Cu-tolerant and control plants. In Cu-tolerant plants, dry matter production was higher than in controls, particularly in roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of copper on periphyton communities assessed in situ using chemical-diffusing substrates

Chemical-diffusing substrates were designed to allow delivery of toxicants to mature periphyton communities under natural conditions without contaminating the surrounding environment. Artificial stream validation studies were conducted in which the effects of substrate-released copper (Cu) on periphyton communities were compared to those generated in a more conventional manner (via water column additions). Effects of copper on the following community parameters were assessed: total community biomass (measured as ash-free dry mass), relative chlorophyll a (chl a and adenosine triphosphate contents, and relative biomass of heterotrophic bacteria. Exposure of more laboratory periphyton communities to substrate-released Cu generated dose-response relationships and recovery models that were indistinguishable from those generated by the conventional route of exposure. The results of this study demonstrate the utility of chemical-diffusing substrates in field validations of laboratory toxicity tests and in investigations of the effects of stress history on periphyton tolerance to toxicants. This revised version was published online in September 2006 with corrections to the Cover Date.     

Impact of environmental pollution on cyanobacterial proline content

This study describes the toxic effects of different prominent aquatic pollutants—heavy metals (Cd & Pb), pesticides (alphamethrin and deltamethrin) and salt (NaCl)—on the intracellular proline content in the cyanobacterium, Westiellopsis prolifica–Janet strain–NCCU331. Despite a reduction in growth (measured as chlorophyll a content), the intracellular proline content increased in the presence of heavy metals, pesticides and high salt concentration. The intracellular cyanobacterial proline accumulation was more pronounced under salt stress than in the presence of pesticides and heavy metals. We have also compared whether or not anionic components influence heavy metal toxicity. It was found that the chlorides of Cd and Pb were more toxic than the NO₃ and the order of toxicity was CdCl₂ > PbCl₂ > Cd (NO₃)₂ > Pb (NO₃)₂. Among pyrethroids, deltamethrin was more toxic than alphamethrin. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Comparison of five cladoceran species in short- and long-term copper exposure

The study was carried out to assess the effect of both short-and long-term copper exposure on five cladoceran species differing in body size and habitat, i.e. Daphnia magna, D. pulex, D. galeata, Bosmina longirostris, and Chydorus sphaericus. The species-specific 48 h EC₅₀ values for fed neonates were used to determine the chronic exposure levels (52% and 65% of the EC₅₀ values). The experiment was run at two food levels. Long-term copper exposure retarded growth in each of the species studied. However, the copper treatments did not affect the clutch sizes of the experimental animals. At a low food level, copper exposure increased mortality in every species studied. The intrinsic rate of increase, r, was reduced in the copper-exposed populations. The sensitivity to copper was higher in the small lake species, compared to D. magna and D. pulex that are commonly used in standard toxicity tests. Of the species studied, B. longirostris had the highest sensitivity to both acute and chronic copper stress. The different sensitivities of the species studied are discussed in an ecological context.     

Quantification of toxic and inhibitory impact of copper and zinc on mixed cultures of sulfate-reducing bacteria

The adverse effects of copper and zinc on an acetate-utilizing mixed cultures of sulfate-reducing bacteria (SRB) at concentrations below the toxic concentration (minimum metal concentration at which no sulfate reduction is observed) are reported in this paper. Mathematical models were developed to incorporate the toxic and inhibitory effects (defined as the reduction in bacterial population upon exposure to the metal and the decrease in the metabolic rate of sulfate reduction by the SRB, respectively) into the sulfate-reduction biokinetics. The characteristic toxicity and inhibition constants were obtained from the measurements of bacterial populations and dissolved metal concentrations in serum bottle studies conducted at 35 degrees C and pH 6.6. Both copper and zinc had toxic and inhibitory effects on SRB. The toxicity constants for copper and zinc were 10.6 and 2.9 mM(-1), respectively, indicating that exposure to copper resulted in a higher mortality of SRB than did exposure to zinc. The values of the inhibition constants were found to be 17.9 +/- 2.5 and 25.2 +/- 1.0 mM(-1) for copper and zinc, respectively. This implies that dissolved zinc was slightly more inhibitory to SRB than copper. The models presented in the paper can be used to predict the response of a sulfate-reduction bioreactor to heavy metals during acid mine drainage treatment.     

Chronological changes in tissue copper, zinc and iron in the toxic milk mouse and effects of copper loading

The toxic milk (tx) mouse is a rodent model for Wilson disease, an inherited disorder of copper overload. Here we assessed the effect of copper accumulation in the tx mouse on zinc and iron metabolism. Copper, zinc and iron concentrations were determined in the liver, kidney, spleen and brain of control and copper-loaded animals by atomic absorption spectroscopy. Copper concentration increased dramatically in the liver, and was also significantly higher in the spleen, kidney and brain of control tx mice in the first few months of life compared with normal DL mice. Hepatic zinc was increased with age in the tx mouse, but zinc concentrations in the other organs were normal. Liver and kidney iron concentrations were significantly lower at birth in tx mice, but increased quickly to be comparable with control mice by 2 months of age. Iron concentration in the spleen was significantly higher in tx mice, but was lower in 5 day old tx pups. Copper-loading studies showed that normal DL mice ingesting 300 mg/l copper in their diet for 3 months maintained normal liver, kidney and brain copper, zinc and iron levels. Copper-loading of tx mice did not increase the already high liver copper concentrations, but spleen and brain copper concentrations were increased. Despite a significant elevation of copper in the brain of the copper-loaded tx mice no behavioural changes were observed. The livers of copper-loaded tx mice had a lower zinc concentration than control tx mice, whilst the kidney had double the concentration of iron suggesting that there was increased erythrocyte hemolysis in the copper-loaded mutants.     

Influences on copper bioaccumulation,growth, and survival of the midge,Chironomus tentans,in metal-contaminated sediments

Sediment bioassays with larvae of the midge, Chironomus tentans, were used to evaluate influences on the bioavailability and toxicity of copper (Cu) in sediments with a wide range of concentrations of metals, acid-volatile sulfide (AVS), and other physicochemical characteristics. Sediments were collected from sixteen lakes in Michigan, USA, and from twelve sites in the Clark Fork River drainage of Montana, USA, which are contaminated with metals from mining activities and from other anthropogenic sources. Bioassays with C. tentans larvae were conducted for ten days in a static-renewal test system, with endpoints of survival, growth, and metal bioaccumulation. Bioaccumulation of copper (Cu) was strongly correlated with Cu concentrations in porewater, and was increased significantly at Cu concentrations less than those affecting growth or survival. Midge survival and growth were not significantly correlated with concentrations of Cu in sediment or porewater, and were poorly predicted by ratios of acid-extractable metals to AVS in sediments. Principal components analysis indicated that Cu concentrations in porewater and bioaccumulation of Cu by midge larvae were influenced by AVS, sediment organic carbon, and porewater pH, and that toxicity was associated with high concentrations of Cu, high concentrations of zinc (Zn) and ammonia. No toxicity was observed in several sediments which contained low concentrations of AVS and high concentrations of Cu and Zn. In sediments which contain little AVS, bioavailability of metals may be controlled by constituents other than sulfides, such as organic matter and metal hydrous oxides. These results indicate that assessments of toxicity in metal-contaminated sediments should evaluate the importance of metal-binding phases other than sulfides, and the possible contributions of ammonia or other toxicants to toxicity in sediment bioassays.The U.S. Government right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.