Development of whole-sediment toxicity identification and evaluation (TIE) techniques for two Australian freshwater species: Chironomus tepperi and Austrochiltonia subtenuis

Abstract

Most of the public literature and available guidance documents on the conduct of freshwater whole-sediment toxicity identification and evaluations (TIEs) detail the use of test organisms and amending agents that are readily available in North America. These commonly used test organisms and the supported amending agents, however, are not available and largely inappropriate (i.e., not native species) for conducting whole-sediment TIEs outside of North America. The overall objective of the present study was to build foundational methods for performing freshwater whole-sediment TIEs in Australia. We examined the capability of 3 amending agents: ANZ38 Zeolite (for ammonia; Castle Mountain Zeolites), Oxpure 325B-9 Activated Carbon (for nonpolar organics; Oxbow Activated Carbon), and Lewatit MonoPlus TP 207 (for cationic metals; Lanxess Deutschland) on 2 Australian native freshwater species: the midge Chironomus tepperi and the amphipod Austrochiltonia subtenuis. To evaluate the effectiveness of each amendment, bioassays were conducted with spiked sediments of ammonia, permethrin (as part of a commercial formulation), and copper using acute median lethal concentrations (LC50s) for both species and growth median effect concentration (EC50) of midges as the endpoints of interest. Environ Toxicol Chem 2017;36:2476-2484. © 2017 SETAC.

Resolving the false-negative issues of the nonpolar organic amendment in whole-sediment toxicity identification evaluations

“…Although powdered coconut charcoal is a more common nonpolar organics amendment (Ho et al 2004;US Environmental Protection Agency 2007;Mehler et al 2010), previous whole-sediment TIE work in Australia has shown the effectiveness of this activated carbon as a nonpolar organics amendment as well (Mehler et al 2017). Sand, to account for any type of dilution effect in TIE testing, was purchased from Chem-Supply and had a size of 300 to 350 mm.…”

“…All bioassays were conducted in 350-mL beakers in the same manner as previous TIE work in Australia (Mehler et al 2017). In each replicate, a total of 60 g wet weight sediment was used with approximately 250 mL of artificial water.…”

“…Activated carbon was added 3 d before the initiation of testing as performed in previous TIE work, and this time frame for amendment addition was utilized in all subsequent bioassays (Mehler et al 2017). Five amendment addition ratios (nominal addition ratios [wet wt activated carbon/wet wt sediment]: 0.25, 0.5, 1.0, 2.5, and 5%) as a well as a control were used to understand the impacts of activated carbon on survival, growth, emergence, and mean development rate of C. tepperi in 2 control sediments (Glynn's Wetland and Bittern Reservoir).…”

“…Preparation details for the chelating resin can be found in previous TIE work (Mehler et al 2017). The general procedure of the whole-sediment field TIE bioassays with contaminated field sediments was the same as discussed in the nonpolar organic-spiked sediment bioassays, with 2 additional treatments included to evaluate the risk of cationic metals.…”

“…In past studies, amendments used in nonpolar organic characterization, namely activated carbon and powdered coconut charcoal, have encountered all 3 types of falsenegative results (US Environmental Protection Agency 2007; Mehler et al 2017). The USEPA guidance (US Environmental Protection Agency 2007) suggests conducting preliminary evaluations with the carbon and test organism of choice to determine the levels, typically on a wet weight basis, that should be used to avoid these issues (typically 2% for fine and 5% for medium charcoal in freshwater sediments).…”