PARENT SESSION
PM11 - Sediment Toxicology
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P313) Bioaccumulation and toxicity of sediment associated herbicides in invertebrates.

Mäenpää, Kimmo^*,1, Sormunen, Arto¹, Kukkonen, Jussi¹, ¹ University of Joensuu, Joensuu, Finland., Finland

ABSTRACT- Benthic macroinvertebrates, Lumbriculus variegatus and Chironomus riparius, were used in toxicity and bioaccumulation tests to determine the toxic concentrations and accumulation potential of sediment associated herbicides, ioxynil, bentazone and pendimethalin. The bioaccumulation tests with L. variegatus were performed in four different sediments, each having different characteristics. Water only LC50 tests were performed with both L. variegatus and C. riparius. A sublethal effect of model compounds in sediments was assessed by C. riparius larvae growth test. Of the model compounds, ioxynil appeared to be the most toxic with LC50 values 4.82 and 7.52 mol L-1 for L. variegatus and C. riparius, respectively. The LC50 water concentrations for bentazone were 329.22 and 259.30 mol L-1 for L. variegatus and C. riparius, respectively. Similarly, ioxynil revealed the highest bioaccumulation potential in bioaccumulation tests. The most important characters affecting chemical fate in the sediment seemed to be the organic matter content and particle size distribution. The bioavailability of compounds in sediments with low organic material and coarse particle size was higher than in more organic sediments. In C. riparius growth tests bentazone had statistically significant effect on larval growth at sediment concentrations 4827 mol kg-1 dw (p<0.05). It is noteworthy that standard deviations tend to be greater at high chemical concentrations, which addresses that part of the individuals started to suffer. Ioxynil exposure had a statistically significant effect on the larval growth in one test sediment at the concentration 41.67 mol kg-1 dw. Generally, head capsule length and larval weight had negative correlation with exposure concentrations in the growth tests. The current results indicate the important role of sediment characteristics on bioavailability and toxicity of sediment associated pesticides.

Key words: Bioaccumulation, Herbicide, Invertebrate, Sediment