Methane stimulates massive nitrogen loss from freshwater reservoirs in India: An international team of researchers has identified an unusual pathway that predominantly facilitates loss of reactive nitrogen from freshwater lake waters, according to the results of the collaborative study now published in the journal Nature Communications.
Human activities are causing the release of enormous amounts of reactive nitrogen (RN) to the environment. India alone accounts for about one-fifth of the global synthetic nitrogen consumption. Unused fertilizers from agriculture together with RN derived from other sources such as sewage discharge and fossil fuel combustion are expected to result in large nitrogen over-enrichment in water bodies both on land and in the sea.
This superabundance promotes excessive growth of algae and the deoxygenation of water. However, an extensive survey of 15 freshwater dam-lakes, spread all over India, revealed unexpectedly low levels of RN.
A team of researchers from India, Germany and the UK around Wajih Naqvi from India's Council of Scientific & Industrial Research (CSIR) and Marcel Kuypers from the Max-Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany, collected a unique set of data - the first of its kind - to better understand the fate and behavior of the RN.
In summer, most of the lakes were found to contain no oxygen below a thin surface layer. These so-called anoxic conditions are suitable for the removal of RN by microorganisms that use oxygen from nitrate, the most abundant form of RN, to breathe.
This conversion of nitrate to biologically inert elemental nitrogen is called denitrification. However, measured denitrification rates were surprisingly low – unless methane was present in the lakes. In the presence of methane, denitrification rates increased 12-fold. Methane is a powerful greenhouse gas that is amply produced in anaerobic freshwater ecosystems.
Anaerobic oxidation of methane by oxidized nitrogen has been known to occur in soils and wetland muds, but this is the first study that shows that nitrate respiration coupled to methane oxidation is a major sink for RN in the water itself. Intriguingly, the microbes known to facilitate this unique linkage elsewhere were rare in the Indian lakes.
Instead, some common methane-oxidizing bacteria were abundant in these anoxic waters. Up to now, these bacteria were thought to live only in the presence of oxygen. They either have an alternative lifestyle, or they work closely with other microbes when oxygen disappears. Apparently, they mediate a phenomenon that is more widespread than believed so far.
"We have identified what we believe is the principal pathway of RN loss from Indian freshwater lakes”, states Naqvi, who led the study while he was a Marie Curie Incoming Fellow at the MPIMM from 2008 to 2011. “This pathway might limit nitrogen over-enrichment - eutrophication - not only in freshwater bodies but also in the coastal ocean. Our results are of enormous environmental significance because they also show unexpectedly low build-up of nitrous oxide, which is commonly known as laughing gas and a potent greenhouse molecule, in Indian lakes. Moreover, anaerobic methane oxidation also constrains methane accumulation in the lakes."
"Similar processes may occur in other freshwater ecosystems where methane is available in significant quantities", predicts Kuypers, who led the German team in the study funded by the European Commission, CSIR, and the Department of Science & Technology (DST), Government of India.
The microbial community structure of the reservoirs examined is quite intriguing. "We are finding new players mediating nitrogen transformations through unexpected pathways – through ‘old players’ in the methane cycle. The study clearly shows that a lot remains to be learnt in this extremely important field of research", says co-author Phyllis Lam, now Associate Professor at Ocean and Earth Science, University of Southampton, UK.
S. Wajih A. Naqvi, Phyllis Lam, Gayatree Narvenkar, Amit Sarkar, Hema Naik, Anil Pratihary, Damodar M. Shenoy, Mangesh Gauns, Siby Kurian, Samir Damare, Manon Duret, Gaute Lavik & Marcel M.M. Kuyper (2018): Methane stimulates massive nitrogen loss from freshwater reservoirs in India. Nature Communications.
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India
Max-Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany
Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, European Way, Southampton, SO14 3ZH, U.K.
Please direct your queries to
Dr. Fanni Aspetsberger
Max Planck Institute for Marine Microbiology
Telefon: +49 421 2028 947
Prof. Dr. Marcel Kuypers
Max Planck Institute for Marine Microbiology
Phone: +49 421 2028 602
Dr. S. Wajih A. Naqvi
Council of Scientific & Industrial Research, Ministry of Science & Technology, Government of India
Phone: +91 11 2347 0222
Dr. Fanni Aspetsberger | Max-Planck-Institut für Marine Mikrobiologie
Decades of satellite monitoring reveal Antarctic ice loss
14.06.2018 | University of Maryland
Scientists find pre-earthquake activity in central Alaska
06.06.2018 | University of Alaska Fairbanks
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
15.06.2018 | Materials Sciences
15.06.2018 | Ecology, The Environment and Conservation
15.06.2018 | Power and Electrical Engineering