Date of Award


Degree Type


Degree Name

Master of Science (MS)




Pb (lead) appears in the environment as a consequence of both natural and anthropogenic processes. Mining, smelting, coal burning, lead acid batteries, and cement manufacturing substantially release Pb into aquatic environments. The goal of this study was to determine the influence of salinity and organism age on chronic toxicity of Pb to Atherinops affinis (topsmelt) in support of development of a species sensitivity distribution (SSD). Species sensitivity distributions assist in ecological risk assessments and establishing quality criteria for contaminants. Three chronic exposure studies were conducted for 28 days in a water flow-through testing system. Survival, standard length, dry weight, and tissue Pb concentration were measured and lethal concentrations (LC), effective concentrations (EC), and bioconcentration factor (BCF) were calculated. In general, increasing salinity and organism age decreased Pb toxicity. The 28-day LC50 values for larval fish at 14 and 28 parts per thousand (ppt) salinity were 15.1 and 79.8 µg/L dissolved Pb, respectively, whereas the 28-d LC50 for juvenile fish was 167.6 µg/L dissolved Pb at 28 ppt salinity. Using standard length, the EC10 values for larval fish were 16.6 and 82.3 µg/L dissolved Pb at low and high salinity, respectively. The dry weight EC25 for low and high salinity were 15.6 and 46.9 µg/L dissolved Pb, respectively. The BCF was higher with the lower salinity study (2.00) in comparison to the higher salinity study (0.73). This is likely due to competition between salt ions and Pb at biotic ligand binding sites as well as lowered Pb speciation rates.

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Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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