Influence of dissolved organic matter (DOM) source on copper speciation and toxicity to Brachionus plicatilis

2016 ◽  
Vol 13 (3) ◽  
pp. 496 ◽  
Author(s):  
Tara N. Tait ◽  
Christopher A. Cooper ◽  
James C. McGeer ◽  
Chris M. Wood ◽  
D. Scott Smith
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Brachionus Plicatilis ◽  
Salt Water ◽  
Copper Toxicity ◽  
Good News ◽  
Toxicity Tests ◽  
Organic Matter Quality ◽  
Degree Of Protection ◽  
Copper Speciation

Environmental context Organic matter dissolved in water can mitigate toxic effects of copper, which should be taken into account when estimating risks of copper pollution. The composition of this organic matter, however, can vary widely, and these variations might also need to be taken into account. This work addresses the question of organic matter quality and demonstrates that only the amount and not the source influences copper toxicity – good news for risk analysis because it simplifies predictions of the effects of copper in specific receiving waters. Abstract The toxicity of copper in marine systems is dependent on its speciation and bioavailability. Dissolved organic matter (DOM) can complex copper, resulting in decreased bioavailability and hence decreased toxicity. The purpose of this study was to measure acute copper LC50 values (concentration lethal to 50% of the organisms) in natural marine waters in a sensitive organism, and identify the relationships between DOM quality and copper toxicity and speciation. Static acute copper toxicity tests (48-h LC50) were performed using the euryhaline rotifer Brachionus plicatilis. Ion-selective electrode measurements of free copper were performed at the LC50 concentrations to determine the influence of DOM source on copper speciation. LC50 values ranged from 333 to 980nM (21.1 to 62.3µgL–1) with DOC concentrations ranging from 0.55 to 7.57mgCL–1. DOC was found to be protective (R2 = 0.72, P = 0.016); however, the degree of protection decreased as DOC increased. This suggests salt-induced colloid formation could be occurring, resulting in a decrease of binding sites available to complex free copper. Free copper remained fairly constant between each sample site, with an average pCu of 10.14. Overall, this study is consistent with other studies that suggest free copper is the best species for predicting toxicity. Additionally, no significant correlation between DOM source and copper toxicity was observed as compared with total DOC concentration and copper toxicity, suggesting that DOM quality does not need to be taken into account for copper toxicity modelling in salt water.

scholarly journals Mimicking floodplain reconnection and disconnection using <sup>15</sup>N mesocosm incubations

2012 ◽  
Vol 9 (11) ◽  
pp. 4263-4278 ◽  
Author(s):  
N. Welti ◽  
E. Bondar-Kunze ◽  
M. Mair ◽  
P. Bonin ◽  
W. Wanek ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Nitrogen Retention ◽  
Danube River ◽  
Nitrous Oxide Emissions ◽  
Organic Matter Quality ◽  
Main River Channel ◽  
Order Of Magnitude ◽  
Floodplain Reconnection ◽  
Floodplain Sediments

Abstract. Floodplain restoration changes the nitrate delivery pattern and dissolved organic matter pool in backwaters, though the effects these changes have are not yet well known. We performed two mesocosm experiments on floodplain sediments to quantify the nitrate metabolism in two types of floodplains. Rates of denitrification, dissimilatory nitrate reduction to ammonium (DNRA) and anammox were measured using 15N-NO3 tracer additions in mesocosms of undisturbed floodplain sediments originating from (1) restored and (2) disconnected sites in the Alluvial Zone National Park on the Danube River downstream of Vienna, Austria. DNRA rates were an order of magnitude lower than denitrification and neither rate was affected by changes in nitrate delivery pattern or organic matter quality. Anammox was not detected at any of the sites. Denitrification was out-competed by assimilation, which was estimated to use up to 70% of the available nitrate. Overall, denitrification was higher in the restored sites, with mean rates of 5.7 ± 2.8 mmol N m−2 h−1 compared to the disconnected site (0.6 ± 0.5 mmol N m−2 h−1). In addition, ratios of N2O : N2 were lower in the restored site indicating a more complete denitrification. Nitrate addition had neither an effect on denitrification, nor on the N2O : N2 ratio. However, DOM (dissolved organic matter) quality significantly changed the N2O : N2 ratio in both sites. Addition of riverine-derived organic matter lowered the N2O : N2 ratio in the disconnected site, whereas addition of floodplain-derived organic matter increased the N2O : N2 ratio in the restored site. These results demonstrate that increasing floodplains hydrological connection to the main river channel increases nitrogen retention and decreases nitrous oxide emissions.

Influence of bedrock geology on dissolved organic matter quality in stream water

2010 ◽  
Vol 41 (11) ◽  
pp. 1177-1188 ◽  
Author(s):  
Jennifer J. Mosher ◽  
Geoffrey C. Klein ◽  
Alan G. Marshall ◽  
Robert H. Findlay
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Stream Water ◽  
Organic Matter Quality ◽  
Bedrock Geology

Copper toxicity toParatya australiensis: III. Influence of dissolved organic matter

1990 ◽  
Vol 9 (8) ◽  
pp. 1013-1018 ◽  
Author(s):  
Helen R. Daly ◽  
Michael J. Jones ◽  
Barry T. Hart ◽  
Ian C. Campbell
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Copper Toxicity

Selection of an organic acid analogue of dissolved organic matter for use in toxicity testing

1999 ◽  
Vol 56 (8) ◽  
pp. 1484-1493 ◽  
Author(s):  
Russell K MacRae ◽  
Ann S Maest ◽  
Joseph S Meyer
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Toxicity Testing ◽  
Binding Constants ◽  
Toxicity Tests ◽  
Conditional Stability ◽  
Copper Binding ◽  
Binding Characteristics ◽  
Geochemical Models ◽  
Stream Waters

Uncontaminated stream waters in the vicinity of a Co mine in Idaho were titrated with Cu to determine the Cu-binding characteristics of natural dissolved organic matter (DOM) and suspended particles. Nonlinear regressions of bound versus free Cu concentrations were consistent with a two-ligand model for DOM complexation of Cu, in which the conditional stability constants (log K) and complexation capacities (CC) were log K1 = 7.26, CC1 = 0.21 µmol Cu·mg dissolved organic carbon (DOC)-1 and log K2 = 5.13, CC2 = 2.89 µmol Cu·mg DOC-1. Copper-binding constants were similar in filtered (0.45 µm) and unfiltered water samples. Calcium, Mg, and Co did not compete appreciably with Cu for DOM complexation at concentrations present in site waters. Copper binding to amorphous iron oxide flocs also was not important at the Fe concentrations present in the stream waters. We selected a mixture of three organic acids, dipicolinic, oxalic, and malonic, to mimic the Cu-binding properties of this DOM. Geochemical models were developed to estimate Cu speciation and evaluate its bioavailability in companion fish toxicity tests using the DOM analogue (Marr et al. 1999. Can. J. Fish. Aquat. Sci. 56: 1471-1483).

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