Development and application of whole‐sediment toxicity test using immobilized freshwater microalgae Pseudokirchneriella subcapitata

Abstract

Abstract-A method for a whole-sediment toxicity test using alginate immobilized microalgae Pseudokirchneriella subcapitata was developed using spiked sediments and applied to contaminated field sediment samples. For method development, a growth inhibition test (72 h) with algal beads was conducted for the sediments spiked with Cu or diuron. The method was validated by determining doseresponse relationships for Cu and diuron in both fine-grained and coarse-grained sediments. The results of a spiked sediment toxicity test suggested that sediment particle size distribution (clay content) had a significant effect on the growth of P. subcapitata. The developed method using immobilized microalgae P. subcapitata beads was applied successfully in the toxicity test and toxicity identification evaluation (TIE) for the four field sediment samples. After a series of extractions with 0.01 M CaCl 2 solution, acetone, and dichloromethane, the extracted sediment, which was shown to be nontoxic to algae, was used as the control and diluent for the same sediment in the whole-sediment toxicity test. The results showed that all investigated field sediment samples were found to be toxic to the immobilized algae P. subcapitata, with their median effective concentration (EC50) values ranging from 41.4 to 79.0% after 72 h exposure. In the whole sediment TIE, growth of P. subcapitata was improved to varying degrees after adding zeolite, resin, or activated charcoal, suggesting different contributions to toxicity from ammonia, metals, and organic contaminants in the tested sediments.

What's causing toxicity in sediments? Results of 20 years of toxicity identification and evaluations

“…Sediment TIEs have been successfully performed in many countries around the world over the last 20 yr [20][21][22][23][24][25][26][27][28]. The present study builds on a 2002 article [29] that analyzed the available set of data at the time (n ¼ 18).…”

Optimisation of Growth of Raphidocelis subcapitata Immobilised for Biofuel Production: Influence of Alginate and CaCl2 Concentrations on Growth

“…The alginate beads are relatively large compared to free cells and can be easily collected through a simple filtration method such as sieving without a significant amount of energy consumed. In addition, although R. subcapitata was incubated under standard microalgal culture conditions, its growth exhibited better results than was found in the literature [46]. This research therefore suggests that optimizing the conditions of culture could provide even more promising results.…”

“…The differences in the growth values observed in the study of Li-Juan Zhang et al [46] could be attributed to the alginate and CaCl 2 concentrations used. The researchers used concentrations higher than what is proposed in this paper because their objective was to obtain dissolution-resistant beads in contaminated freshwater sediments.…”

“…This is a decrease The growth value of R. subcapitata obtained in this study under the optimal conditions of immobilization (2% alginate and 1% CaCl 2 ) was higher than the values reported in other articles. Li-Juan Zhang et al [46] obtained a growth of 18.5 × 10 4 ± 0.3 cells/mL under the optimal immobilization conditions, which were determined to be 4% alginate and CaCl 2 , after three days of culture. If the growth value of the study presented here is converted into the same unit, it gives a growth of 34.3 × 10 4 ± 0.34 cells/mL after three days of culture.…”

Guanicid and PHMG Toxicity Tests on Aquatic Organisms

“…These algae species belong to the order Chlorococcales and are usually unicellular in culture (ČNI, 2005). Algae are common test organisms susceptible to many toxic substances, and thus are widely used in toxicity tests (Zhang, 2012).…”