Adverse Effects of Ammonia on Nitrification Process: the Case of Chinese Shallow Freshwater Lakes

Abstract

Nitrification is a process in which ammonia is oxidized to nitrite (NO 2 − ) that is further oxidized to nitrate (NO 3 − ). The relations between these two steps and ambient ammonia concentrations were studied in surface water of Chinese shallow lakes with different trophic status. For the oxidations of both ammonia and NO 2 − , more eutrophic lakes generally showed significantly higher potential and actual rates, which was linked with excessive ammonia concentrations. Additionally, both potential and actual rates for ammonia oxidation were higher than those for NO 2 − oxidation in the more eutrophic lakes, while in the lakes with lower trophic status, both potential and actual rates for ammonia oxidation were almost equivalent to those for NO 2 − oxidation. This can be explained by the excessive unionized ammonia (NH 3 ) concentration that inhibits nitrite-oxidizing bacteria in the more eutrophic lakes. The laboratory experiment with different ammonia concentrations, using the surface water in a eutrophic lake, showed that ammonia oxidation rates were proportional to the ammonia concentrations, but NO 2 − oxidation rates did not increase in parallel. Furthermore, NO 2 − oxidation was less associated with particles in natural water of the studied lakes. Without effective protection, it would be selectively inhibited by the excessive ammonia in hypereutrophic lakes, resulting in NO 2 − accumulation.Shortly, the increased concentrations of ammonia cause a misbalance between the NO 2 − -producing and the NO 2 − -consuming processes, thereby exacerbating the lake eutrophication.

Ice duration drives winter nitrate accumulation in north temperate lakes

“…Controls on nitrification in such lakes may also include: levels of connectivity between sediment microbes, N pools, and water column oxygen sources; exposure to excess light (French et al ), ammonium (Chen et al ), acidity (Jeschke et al ), or anthropogenic pollutants such as metals or pharmaceuticals (Kraigher and Mandic‐Mulec ; Rosi‐Marshall and Royer ); competition for ammonium or nitrite by heterotrophic microbes or algae (Agbeti and Smol ), which may be elevated in lakes with high sediment‐water contact or primary productivity. In unpolluted freshwaters, nitrite is thought to occur at trace concentrations and nitrite oxidation is not commonly viewed as a rate‐limiting step of nitrification, although nitrite may sometimes accumulate to toxic concentrations in agricultural streams or groundwater (Stanley and Maxted ; Chen et al ). While these factors can influence spatio‐temporal variability in gross or net N transformation rates, understanding of total winter production of nitrate and ammonium could be enhanced through ecosystem‐level studies that employ long‐term winter data.…”

Water Quality of Streams Receiving Municipal Waste Water in Port Harcourt, Niger Delta, Nigeria

“…al., 2007, Hill et. al., 2005and Chen, 2010. Similarly other indices implicating municipal waste discharges on the stream systems are the high total coliform and faecal coliform concentrations observed in the water bodies which are below concentrations recorded in most of the systems in the past studies (Amadi et.…”

“…al., 2005. The study shows that the rapid growth of Port Harcourt and associated municipal wastes introduced into the five main steams have caused the deterioration of the water quality of the streams and therefore presents the need for a better waste management system (Chen, 2010).…”

Changes in rainfall level and litter stoichiometry affect aquatic community and ecosystem processes in bromeliad phytotelmata

“…CH 4 ) out from the sediment to the water column(Figueiredo-Barros et al, 2009). High NH + 4 concentrations delay the nitrification process (conversion of NH + 4 into NO − 3 ), a key step in the loss of this compound, which, in large amounts, is toxic for the organisms that comprise the aquatic community(Chen, Cao, Song, & Zhou, 2010). Our results suggest that Naididae might control the accumulation and flux of organic matter, as well as of NH + 4 , in the bromeliad aquatic system.…”