Toxicity Of Un-ionized Ammonia Research Articles

Toxicity of ammonia to nine native New Zealand freshwater invertebrate species

The toxic concentration for un-ionized ammonia (NH3) was assessed for nine native New Zealand invertebrate species. The 96-h EC50 values at 15°C and pH 7.6 and pH 8.2 ranged from 0.18 to >0.8 g/m3 NH3. The rank of species sensitivity was: shrimp (Paratya curvirostris) (least) ≈ mayfly (Zephlebia dentata) ≈ stonefly (Zealandobius furcillatus) < Oligochaeta (Lumbriculus variegatus) < fingernail clam (Sphaerium novaezelandiae) < mayfly (Deleatidium spp.) < a snail (Potamopyrgus antipodarum) < caddis (Pycnocentria evecta) < crustacean (Paracalliope fluviatilis) (most). Surprisingly, the more sensitive species were those which would normally be associated with lowland streams (the snail and crustacean) rather than the normally accepted “sensitive” species (mayflies and stoneflies). Temperature had no significant effect on the acute toxicity of un-ionized ammonia with snails tested at 15, 20, and 25°C. The invertebrates were more sensitive than the native fish species tested (inanga, EC50 1.60 g/m3 NH3; Richardson 1991). A final acute value (FAV) calculated for these species was 0.15 g/m3 NH3. This compares with the FAV value of 0.52 g/m3 NH3 derived by the US Environmental Protection Agency (EPA) as the basis for the ammonia criterion for salmonid containing waters. Thus EPA criteria may not provide adequate protection for New Zealand species. These data suggest that chronic studies would be particularly desirable on native New Zealand species to better determine their sensitivity to long term ammonia exposure.

Lethal Effects of Elevated pH and Ammonia on Early Life Stages of Hybrid Striped Bass

Hybrid striped bass larvae (striped bass, Morone saxatilis, ♀ x white bass, M. chrysops, ♂) are often stocked into fertile culture ponds. High rates of photosynthesis may result in elevated pH which can be lethal to fry and can affect the toxicity of ammonia. Six-hour static toxicity tests were performed on hybrid larvae of various ages to determine the toxicity of elevated pH and the effects of elevated pH on ammonia toxicity. Six-hour mortality threshold pH's with no measurable ammonia were estimated for various age larvae and found to be between pH's 9.8 and 10.2 for D2 (Dl is day of hatch), between 9.0 and 9.4 for D4, between 8.8 and 9.2 for D13, and between 9.2 and 9.4 for D20 fish. The addition of 0.7% NaCl had no effect on the toxicity of elevated pH to D2 or D4 fish but caused a significant reduction in the mortality of Dl3 and D20 fish exposed to high pH. The tolerance to elevated pH decreased as ammonia concentration increased. Sub-lethal un-ionized ammonia concentrations increased the toxicity of elevated pH, suggesting an interaction of pH and un-ionized ammonia toxicity.

Effects of Sodium and Calcium on Acute Toxicity of Un-ionized Ammonia to Atlantic Salmon and Lake Trout

Acute, static 6-hour toxicity tests were conducted on two sizes each of lake trout and Atlantic salmon in the presence of three levels each of NaCl and CaCl2. Calcium did not protect smolts from NH3 toxicity but had no effect on the tolerance of Atlantic salmon fry to NH3. Both cations increased the tolerance of 8-g lake trout fingerlings to NH3, but neither significantly affected the toxicity of NH3 to 0.9-g lake trout fry. These results suggest that the mitigating effects of solution cations of NH3 toxicity may be related to species, size, and life stage.

The acute and chronic toxicity of ammonia to marine fish and a mysid

The acute toxicity (96-hr LC50) of un-ionized ammonia to mysids (Mysidopsis bahia) and larval inland silversides (Menidia beryllina) was influenced by pH and salinity in a species specific manner. With mysids, NH3 was most toxic at pH 7.0 and less toxic at pH 8.0 and 9.0. In contrast, NH3 toxicity to inland silversides was greatest at pH 7.0 and 9.0 and lowest at pH 8.0. A drop in salinity from 31 g/kg to 11 g/kg uniformly increased toxicity to mysids over this pH range. In contrast, in silversides at 11 g/kg, NH3 toxicity was less at pH 7.0, greater at pH 8, and slightly less at pH 9, relative to the toxicity at 31 g/kg. Temperature had no significant effect on the acute toxicity of un-ionized ammonia with acclimated mysids tested at 18, 25 and 32.5 degrees C, but did have a small effect with acclimated larval sheepshead minnows (Cyprinodon variegatus) tested at 13, 25 and 32.5 degrees C. The chronic toxicity value (the geometric mean of the highest no-effect concentration and lowest effect concentration) at pH 8.0, 25 degrees C and 31 g/kg salinity is 0.061 mg NH3/L for inland silversides and 0.232 mg NH3/L for mysids; the acute:chronic ratio is 21.3 and 7.2, respectively.

Ammonia Toxicity to Chinook Salmon Parr: Reduction in Saline Water

The acute toxicity of un-ionized ammonia (NH3) to parr of chinook salmon Oncorhynchus tshawytscha in fresh water and in water of four different salinities was determined in 24-hour static tests. The 24-hour median lethal concentration (LC50) in fresh water was 0.36 mg NH3/liter. The LC50 at a salinity of 9.6‰ was considerably higher (2.2 mg NH3/liter). Lower LC50 values, indicating greater toxicity, were obtained in water of both lesser and greater salinity. Reduction of ammonia toxicity is a major benefit of brackish-water culture of chinook salmon. Received February 8, 1982 Accepted August 5, 1983

Acute Toxicity of Un-ionized Ammonia to Fingerling Coho Salmon

Abstract Duplicate groups of fingerling coho salmon (Oncorhynchus kisutch) were exposed to nine concentrations of un-ionized ammonia for 96 h. The LC50 was 0.45 mg un-ionized NH3N per liter (95% confidence limits, 0.43 to 0.47). Acute lethality ceased relatively early, presumably from an acceleration of biosynthetic detoxifying reactions, as shown by blood urea nitrogen measurements.

Evaluation of the short-term toxicity of nitrogenous compounds to channel catfish, Ictalurus punctatus

The acute toxicity of un-ionized ammonia, nitrite, and nitrate to 50–76-mm fingerling channel catfish ( Ictalurus punctatus) was investigated using a static bioassay system at 22, 26 and 30°C. The 96-h LC50 values at 30°C for un-ionized ammonia, nitrite, and nitrate were 3.8, 44, and 6 200 mg/l.