Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures

Abstract

Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia‐spiked sediments reduced pore‐water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ≥70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia‐spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.

Sensitivity of juvenile freshwater mussels (Lampsilis fasciola, Villosa iris) to total and un-ionized ammonia

“…Ammonia toxicity varies widely among invertebrate taxa, and uncertainty exists as to whether ammonia toxicity is at tributable primarily to the un‐ionized form and mechanisms responsible for toxicity [8–11]. Documented toxic effects of ammonia solutions to freshwater and marine bivalves include reduction in the amount of time valves are held open for respiration and feeding [12]; impaired secretion of the byssus thread [13]; reduced ciliary action [6,14]; depleted lipid, glycogen, and other carbohydrate stores; and altered metabolism [15] as well as acute toxicity [7,16,17].…”

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

“…Zeolite has been successfully used to preferentially bind ammonia , and it was expected that the zeolite produced in Australia would be no different. The zeolite amendment ANZ38 is mined, produced, and manufactured in Australia (Castle Mountain Zeolites).…”

“…Zeolite was rinsed with deionized water and allowed to rest overnight before being decanted before use, resulting in a thick paste that could be added to test sediments. An amending ratio of 20% (via wet wt) was used in TIE bioassays, based on published literature with similar zeolite products .…”

Application of toxicity identification evaluation to sediment in a highly contaminated water reservoir in southeastern Brazil

“…In each batch test, 20 g of the resin were added to 200 ml of sample (10% w/v). After 24 h of contact with moderate stirring, the sample was passed through a filter paper [27]. A range of concentrations of the filtrate (100.0, 50.0, 25.0, and 12.5%) was tested with C. dubia.…”