INFLUENCE OF pH ON THE TOXICITY OF AMMONIA TO CHIRONOMUS TENTANS AND LUMBRICULUS VARIEGATUS

Abstract

The U.S. Environmental Protection Agency water-quality criteria establish permissible levels of ammonia in the nation's fresh waters. These criteria are based on accumulated research suggesting that, for most aquatic species (primarily fishes), the toxicity of un-ionized ammonia predominates over that of the ammonium ion. The development of a sediment-quality criterion for ammonia requires evaluation of the relative toxicity of the two ammonia forms to benthic and epibenthic macroinvertebrates to determine whether the water-quality toxicity model can be applied to sediments. Flow-through ammonia toxicity tests were conducted over 10 d with the oligochaete Lumbriculus variegatus and the larval midge Chironomus tenfans at four pH values (6.3, 7.2, 7.8, and 8.6) using a unique pH control system. Total ammonia was more toxic at elevated than at low pH to both species, suggesting that un-ionized ammonia (more prevalent at high pH) is important in determining the toxicity of ammonia to these two species. Hardness or alkalinity differences in the range of 30 to 200 mg/kg (as CaCO,) did not appear to affect the toxicity of ammonia to the two species in separate 4-d tests. Based on results of the 10-d tests, the joint toxicity/pH model that establishes the water-quality criterion value for ammonia appears to be sufficiently protective of L. variegatus and C. tentans, by factors of at least 3 and 10, respectively. However, this study did not address potential differences in exposure of benthic organisms to ammonia in sediments vs. that in the water column; nor were the chronic effects of ammonia on these species measured in this study.

Structure of Macrozoobenthos of the East Dongting Nature Reserve, with Emphasis on Relationships with Environmental Variables

“…Ca-poor environments could be limiting for snail eggshell formation and skeletal growth in nestlings, and during the reproduction period, snails usually concentrate on Ca-high zones (Tipping et al 2002, Scheuhammer et al 1997, Graveland et al 1994, Schubauer-Berigan et al 1995. Compared to oligochaetes and insects, mollusks may be more acid-sensitive, since Ca concentration is negatively related to acidification (Scheuhammer et al 1997).…”

Short-term responses of Oryzias latipes (Pisces: Adrianichthyidae) and Macrobrachium nipponense (Crustacea: Palaemonidae) to municipal and pharmaceutical waste water in Beijing, China: survival, behaviour, biochemical biomarkers

“…EROD and AHH were low and could not differentiate between pharmaceutical waste water before and after treatment (P-IF and P-EF). The waste water treatment reduced N-toxicity for prawn by creating slightly alkaline conditions, which resulted in a shift from NH 3 to less toxic NH þ 4 (Burkhard and Jenson, 1993;Schubauer-Berigan et al, 1995). The effluent contained up to 10.9 mg l À1 nitrite.…”

pH dependent toxicity of five metals to three marine organisms

“…lower pHs Walker et al, 1996 . However, empirical studies have indicated toxicity changes are often metal Ž and organism dependent Campbell and Stokes, 1985;Schubauer-Berigan et al, 1993;Sandifer and Hopkin, . 1996;Walker et al, 1996;Cuismano et al, 1986.…”

“…Metal toxicity is often dependent upon pH in freshwa-Ž ter and soils Campbell and Stokes, 1985;Schubauer-. Berigan et al, 1993;Sandifer and Hopkin, 1996 .…”