Abstract
Dissolved organic carbon (DOC), through its ability to complex metals and thereby reduce their bioavailability, plays a major role in ameliorating metal toxicity in natural waters. Indeed DOC is a key variable in the Biotic Ligand Model (BLM) for predicting metal toxicity on a site-specific basis. However, recent evidence indicates that all DOCs are not alike, but rather heterogeneous in their ability to protect organisms against metal toxicity, at least in fresh water. The degree of protection appears to correlate with optical properties, such that dark, aromatic-rich compounds of allochthonous origin, with greater humic acid content, are more effective in this regard, particularly against Cu, Ag, and Pb toxicity. The specific absorption coefficient of the DOC in the 300-350nm range (SAC 300-350) has proven to be a simple and effective index of this protective ability. PARAFAC, a multivariate statistical technique for analysis of excitation-emission fluorescence spectroscopy data, also holds promise for quantifying the humic-like and fulvic-like fluorophores, which tend to be positively and negatively correlated with protective ability, respectively. However, what has been largely missing in the toxicological realm is any appreciation that DOC may also affect the physiology of target organisms, such that part of the protection may occur by a mechanism other than metal complexation. Recently published evidence demonstrates that DOC has effects on Na + transport, diffusive permeability, and electrical properties of the gills in fish and crustaceans in a manner which will promote Na + homeostasis. These actions could thereby protect against metal toxicity by physiological mechanisms. Future research should investigate potential direct interactions of DOC molecules with the branchial epithelium. Incorporation of optical properties of DOC could be used to improve the predictive capabilities of the BLM.
| Original language | English |
|---|---|
| Pages (from-to) | 3-8 |
| Number of pages | 6 |
| Journal | Aquatic Toxicology |
| Volume | 105 |
| Issue number | 3-4 SUPPL. |
| DOIs | |
| Publication status | Published - Oct 2011 |
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Keywords
- Aromaticity
- Dissolved organic carbon
- Gill physiology
- Metal toxicity
- Natural organic matter
- PARAFAC
ASJC Scopus subject areas
- Aquatic Science
- Health, Toxicology and Mutagenesis
Cite this
The two faces of DOC. / Wood, Chris M.; Al-Reasi, H. A.; Smith, D. Scott.
In: Aquatic Toxicology, Vol. 105, No. 3-4 SUPPL., 10.2011, p. 3-8.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The two faces of DOC
AU - Wood, Chris M.
AU - Al-Reasi, H. A.
AU - Smith, D. Scott
PY - 2011/10
Y1 - 2011/10
N2 - Dissolved organic carbon (DOC), through its ability to complex metals and thereby reduce their bioavailability, plays a major role in ameliorating metal toxicity in natural waters. Indeed DOC is a key variable in the Biotic Ligand Model (BLM) for predicting metal toxicity on a site-specific basis. However, recent evidence indicates that all DOCs are not alike, but rather heterogeneous in their ability to protect organisms against metal toxicity, at least in fresh water. The degree of protection appears to correlate with optical properties, such that dark, aromatic-rich compounds of allochthonous origin, with greater humic acid content, are more effective in this regard, particularly against Cu, Ag, and Pb toxicity. The specific absorption coefficient of the DOC in the 300-350nm range (SAC 300-350) has proven to be a simple and effective index of this protective ability. PARAFAC, a multivariate statistical technique for analysis of excitation-emission fluorescence spectroscopy data, also holds promise for quantifying the humic-like and fulvic-like fluorophores, which tend to be positively and negatively correlated with protective ability, respectively. However, what has been largely missing in the toxicological realm is any appreciation that DOC may also affect the physiology of target organisms, such that part of the protection may occur by a mechanism other than metal complexation. Recently published evidence demonstrates that DOC has effects on Na + transport, diffusive permeability, and electrical properties of the gills in fish and crustaceans in a manner which will promote Na + homeostasis. These actions could thereby protect against metal toxicity by physiological mechanisms. Future research should investigate potential direct interactions of DOC molecules with the branchial epithelium. Incorporation of optical properties of DOC could be used to improve the predictive capabilities of the BLM.
AB - Dissolved organic carbon (DOC), through its ability to complex metals and thereby reduce their bioavailability, plays a major role in ameliorating metal toxicity in natural waters. Indeed DOC is a key variable in the Biotic Ligand Model (BLM) for predicting metal toxicity on a site-specific basis. However, recent evidence indicates that all DOCs are not alike, but rather heterogeneous in their ability to protect organisms against metal toxicity, at least in fresh water. The degree of protection appears to correlate with optical properties, such that dark, aromatic-rich compounds of allochthonous origin, with greater humic acid content, are more effective in this regard, particularly against Cu, Ag, and Pb toxicity. The specific absorption coefficient of the DOC in the 300-350nm range (SAC 300-350) has proven to be a simple and effective index of this protective ability. PARAFAC, a multivariate statistical technique for analysis of excitation-emission fluorescence spectroscopy data, also holds promise for quantifying the humic-like and fulvic-like fluorophores, which tend to be positively and negatively correlated with protective ability, respectively. However, what has been largely missing in the toxicological realm is any appreciation that DOC may also affect the physiology of target organisms, such that part of the protection may occur by a mechanism other than metal complexation. Recently published evidence demonstrates that DOC has effects on Na + transport, diffusive permeability, and electrical properties of the gills in fish and crustaceans in a manner which will promote Na + homeostasis. These actions could thereby protect against metal toxicity by physiological mechanisms. Future research should investigate potential direct interactions of DOC molecules with the branchial epithelium. Incorporation of optical properties of DOC could be used to improve the predictive capabilities of the BLM.
KW - Aromaticity
KW - Dissolved organic carbon
KW - Gill physiology
KW - Metal toxicity
KW - Natural organic matter
KW - PARAFAC
UR - http://www.scopus.com/inward/record.url?scp=81355122620&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=81355122620&partnerID=8YFLogxK
U2 - 10.1016/j.aquatox.2011.03.007
DO - 10.1016/j.aquatox.2011.03.007
M3 - Article
VL - 105
SP - 3
EP - 8
JO - Aquatic Toxicology
JF - Aquatic Toxicology
SN - 0166-445X
IS - 3-4 SUPPL.
ER -