Copper Speciation and Binding by Organic Matter in Copper-Contaminated Streamwater

Breault, Robert F.; Colman, John A.; Aiken, George R.; McKnight, Diane M.

doi:10.1021/es9601301

Cited by 127 publications

(87 citation statements)

References 37 publications

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“…However, the free Cu concentrations in planktonic cultures grown in MSVP did not change significantly during growth as P. aeruginosa consumed pyruvate (data not shown). The concentrations of added heavy metals used in this study do exceed many reported values for the total metal concentrations at contaminated sites (3,9,42). However, the amounts of a free ion and the different complexes that it forms are poorly understood in environmental systems.…”

Section: Discussionmentioning

confidence: 54%

Heavy Metal Resistance of Biofilm and Planktonic Pseudomonas aeruginosa

Teitzel

Parsek

2003

Appl Environ Microbiol

597

373

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A study was undertaken to examine the effects of the heavy metals copper, lead, and zinc on biofilm and planktonic Pseudomonas aeruginosa. A rotating-disk biofilm reactor was used to generate biofilm and freeswimming cultures to test their relative levels of resistance to heavy metals. It was determined that biofilms were anywhere from 2 to 600 times more resistant to heavy metal stress than free-swimming cells. When planktonic cells at different stages of growth were examined, it was found that logarithmically growing cells were more resistant to copper and lead stress than stationary-phase cells. However, biofilms were observed to be more resistant to heavy metals than either stationary-phase or logarithmically growing planktonic cells. Microscopy was used to evaluate the effect of copper stress on a mature P. aeruginosa biofilm. The exterior of the biofilm was preferentially killed after exposure to elevated concentrations of copper, and the majority of living cells were near the substratum. A potential explanation for this is that the extracellular polymeric substances that encase a biofilm may be responsible for protecting cells from heavy metal stress by binding the heavy metals and retarding their diffusion within the biofilm.Heavy metals are ubiquitous and persistent environmental pollutants that are introduced into the environment through anthropogenic activities, such as mining and smelting, as well as through other sources of industrial waste. In fact, over one-half the superfund sites in the United States are contaminated with at least one heavy metal (www.atsdr.cdc.gov). Heavy metals contaminate drinking water reservoirs and freshwater habitats and can alter macro-and microbiological communities (18, 24). The known mechanisms of heavy metal toxicity include inducing oxidative stress and interfering with protein folding and function (30).Bacteria have developed a variety of resistance mechanisms to counteract heavy metal stress. These mechanisms include the formation and sequestration of heavy metals in complexes, reduction of a metal to a less toxic species, and direct efflux of a metal out of the cell (30-33). Pseudomonas aeruginosa is a ubiquitous, environmentally important microbe that may employ many resistance mechanisms, such as the mer operon that reduces toxic Hg 2ϩ to volatile Hg 0 , which then diffuses out of the cell (33). However, in bacteria, efflux systems are a more common resistance mechanism for dealing with heavy metals. One such system is the cop system of Pseudomonas syringae, which contains the structural genes copABCD and is homologous to the pco system in Escherichia coli. The copB and copD genes are involved in the transport of copper across the membrane, while the products of the copA and copC genes are outer membrane proteins that bind Cu 2ϩ in the periplasm, protecting the cell from copper (6, 36). Other types of efflux systems simply pump toxic metal ions out of the cell; these systems include the P-type ATPase cadA, which was first identified in Staphylococcus aureus and...

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Section: Discussionmentioning

confidence: 54%

Heavy Metal Resistance of Biofilm and Planktonic Pseudomonas aeruginosa

Teitzel

Parsek

2003

Appl Environ Microbiol

597

373

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“…In modeling the light regime of a lake under different conditions, DOC-related parameters could be chosen on the basis of a measurement of fluorescence index. Further, it has been found that the metal-binding properties of fulvic acid can vary significantly with source (Breault et al 1996), and fluorescence may be a useful tool in refining metal-fulvic acid formation constants for application of metal-ion binding models to field studies (Benedetti et al 1996). This method may be useful for sorting large sample sets to be tested by other characterization methods or for characterization of archived samples.…”

Section: Potential Applicationsmentioning

confidence: 99%

Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity

McKnight

Boyer

Westerhoff

et al. 2001

Limnology & Oceanography

2,444

1,810

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We studied the fluorescence properties of fulvic acids isolated from streams and rivers receiving predominantly terrestrial sources of organic material and from lakes with microbial sources of organic material. Microbially derived fulvic acids have fluorophores with a more sharply defined emission peak occurring at lower wavelengths than fluorophores in terrestrially derived fulvic acids. We show that the ratio of the emission intensity at a wavelength of 450 nm to that at 500 nm, obtained with an excitation of 370 nm, can serve as a simple index to distinguish sources of isolated aquatic fulvic acids. In our study, this index has a value of ϳ1.9 for microbially derived fulvic acids and a value of ϳ1.4 for terrestrially derived fulvic acids. Fulvic acids isolated from four large rivers in the United States have fluorescence index values of 1.4-1.5, consistent with predominantly terrestrial sources. For fulvic acid samples isolated from a river, lakes, and groundwaters in a forested watershed, the fluorescence index varied in a manner suggesting different sources for the seepage and streamfed lakes. Furthermore, we identified these distinctive fluorophores in filtered whole water samples from lakes in a desert oasis in Antarctica and in filtered whole water samples collected during snowmelt from a Rocky Mountain stream. The fluorescence index measurement in filtered whole water samples in field studies may augment the interpretation of dissolved organic carbon sources for understanding carbon cycling in aquatic ecosystems.Aquatic fulvic acid is a major fraction of dissolved organic matter (DOM) in natural waters. Aquatic fulvic acids are heterogeneous, moderate molecular weight, yellow-colored organic acids. Examples of processes controlled by fulvic acid are (1) chemical speciation and transport of trace metals through complexation reactions (e.g., Breault et al. 1996); (2) formation of trihalomethanes in drinking water by interactions between chlorine and fulvic acid during water AcknowledgmentsWe thank K. Cunningham for help with spectroscopic methods and G. Aiken, J. Debroux, P. Coble, and four anonymous reviewers for valuable comments on the manuscript.

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“…A part of the metals deposited in the sediments are absorbed by aquatic plants such as Paspalum distichum, the dominating aquatic plant, and plankton. Residual bodies of aquatic organism deposited into sediments and bring about the enrichment of heavy metals owning to the increase of organic matter [33]. The origin of sedimentary organic matter can be distinguished by the C/N ratio of compositions of different aquatic plants.…”

Section: Discussionmentioning

confidence: 99%

Ecological Risk Assessment Of Heavy Metals In Sediments Of A Riverine Wetland, Huaihe River Watershed, China

Yuan

Pan

Zhu

et al. 2015

Ecological Chemistry and Engineering S

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Abstract:The concentrations of Zn, Cr, Cu, As, Cd, and Pb in sediment cores collected from a representative riverine wetland located in the Huaihe River watershed, China, dramaticlly increased from the bottom to upper layer of the cores. Application of principal component analysis (PCA) and enrichment factor (EF) suggested that heavy metals might primarily have been derived from the inflow of contaminated water from an industrial park and agricultural region. Component 1 of the PCA was dominated by Zn, Cr, Cu, Cd, and Pb, while Component 2 was dominated by As. Metals' high concentrations and EF values showed that the anthropogenic pollutants have increased sharply in recent years and reflect the continuous development of industry and agriculture in the region of the wetland, with a corresponding dramatic deterioration of the environment due to constant effluent of pollutants. Cd exerted the highest potential ecological risk of individual metals of sediment cores. Additionally, integrated RI values for all metals indicated that sediments possessed low ecological risk from the bottom to about 6 cm depth of the cores, moderate ecological risk from about 5 cm depth upwards, then considerable ecological risk from 4 cm depth to the top layer of the sediment cores, which demonstrates a continuous deterioration of environmental quality in recent years in this region.

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Copper Speciation and Binding by Organic Matter in Copper-Contaminated Streamwater

Cited by 127 publications

References 37 publications

Heavy Metal Resistance of Biofilm and Planktonic Pseudomonas aeruginosa

Heavy Metal Resistance of Biofilm and Planktonic Pseudomonas aeruginosa

Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity

Ecological Risk Assessment Of Heavy Metals In Sediments Of A Riverine Wetland, Huaihe River Watershed, China

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