미국 지질연구소(USGS) 소속의 과학자들은 버지니아 해양과학연구소 및 코네티컷대학교 연구진과의 협업으로 분야 최초로 지하수에서의 아나목스(anammox) 활동량을 연구하고, 지하수 내에서 질소제거는 자연적으로 발생하는 박테리아의 활동을 통해 일어날 수 있다는 사실을 입증했다.

‘혐기성암모늄산화(anaerobic ammonium oxidation)’, 즉 아나목스는 자연적으로 발생하는 박테리아에 의해 수행된 과정으로 박테리아는 유해 질소가스 생산을 위해 두 성분을 결합하면서 암모늄 제거와 질소산화물 저감을 동시에 할 수 있다.

 

 

 

Scientists from the U.S. Geological Survey (USGS) -- in collaboration with partners from the Virginia Institute of Marine Science and the University of Connecticut -- have conducted the first-ever field measurements of anammox activity in groundwater, demonstrating that nitrogen removal from groundwater can occur through the action of naturally occurring bacteria.

 

Anammox, short for "anaerobic ammonium oxidation," is a process carried out by naturally occurring bacteria that can simultaneously remove ammonium and reduce nitrogen oxides (such as nitrate and nitrite), combining the two to produce harmless nitrogen gas.

 

Over the past 100 years, humans have drastically altered the global nitrogen budget by fixing nitrogen gas from air to produce fertilizer in the form of ammonium and nitrate. Nitrate and ammonium are now prevalent fixed nitrogen contaminants that may be found in surface water and groundwater worldwide. Until fixed nitrogen is converted back to nitrogen gas, it remains as a potential water contaminant. Anammox and denitrification are the only two processes that can remove excess fixed nitrogen by chemically changing it back to nitrogen gas.

 

Discovered just 20 years ago in wastewater treatment systems, anammox has been studied since then in laboratory settings using enrichment cultures. Relatively recently, anammox was found to be ecologically important in marine and other surface water environments.

 

Working at a carefully monitored USGS groundwater study site at Cape Cod, Mass., the research team found that anammox was active in the subsurface in a variety of geochemical conditions, even where groundwater ammonium concentrations were low. The rates of activity were relatively low, but anammox could potentially affect inorganic nitrogen concentrations in situations where groundwater residence times are sufficiently long.

 

The paper documents the competition between anammox and denitrification for nitrogen oxides and explores the effect of altered organic carbon concentrations on that competition. The results of this study indicate that anammox does occur in groundwater, that it can be an important mechanism for fixed nitrogen removal, and that it should be included when interpreting subsurface geochemistry and constructing groundwater nitrogen budgets.

 

[출처 = Water World / 2015년 11월 5일]