Ocean pollution caused by fertilisers is increasing at a fast rate. Since the 1970s the riverine input of nitrogen and phosphor into the sea has tripled leading to excessive algal growth in many regions, which in turn threatens valuable ecosystems such as coral reefs.
Researchers from the Leibniz Center for Tropical Marine Ecology (ZMT) have conducted measurements in a densely populated river basin in India. Besides agricultural use of the hinterland, there is another prominent reason of water pollution: the largest pilgrimage on earth – the Sabarimala Temple. During their studies the ZMT researchers made a surprising discovery – the Pamba River in the Indian state of Kerala is less contaminated by nutrients than, for example, the German Weser River.
A high population density, untreated sewage, use of fertilisers on farmland: Southeast Asian rivers are highly contaminated with nutrients such as nitrogen and phosphorus. During the monsoon season torrential rains wash large quantities of pollutants into the rivers. Data about ocean pollution caused by riverine input are plentiful in industrial nations, but are still rare in developing and emerging countries.
Dr. Tim Jennerjahn, a biogeochemist at the ZMT, and his PhD student Shilly Elizabeth David looked at the contamination of the Pamba River in the southern Indian state of Kerala, which has a population of more than 33 million. The results of their study have just been published in the journal “Science of the Total Environment”.
The Pamba River with a length of 176 km rises in the Western Ghats mountains, flows through the Kerala State and discharges into the Vembanad lake which, in turn, provides the connection to the Arabian Sea. An average of 400 people live within one square kilometre of land in the river catchment.
The ZMT scientists tested different sections of the river characterized by specific land uses like tea and rubber plantations, settlements with horticulture, rice crops and the pilgrimage site of the Sabarimala Temple. More than 50 million Hindus from all over the world flock to the sanctuary each year. Every day countless pilgrims take a bath in the Pamba to wash away their sins.
“Near the Sabarimala Temple we found large quantities of ammonium nitrogen as a result of human waste. We measured 3.1 kg per hectare and year,” says Tim Jennerjahn. “Close to the pilgrimage site the phosphorus load from detergents was also high.” With 5.6 kg per hectare and year the concentration of nitrate nitrogen resulting from fertilisers used in plantations and gardens was also considerable in the corresponding sections of the rivers.
“It has still come as a bit of a surprise to us that the nutrient load in such a densely populated area is lower than in German rivers such as the Weser, for example,” says Dr. Jennerjahn. “Lower-Saxony has a problem with manure, too much of it is washed from the fields into the Weser.”
While the Weser carries an average nitrogen load of 12 kg per hectare and year, the Pamba only contains 3.5 kg on average. In the Vembanad lake, forming the estuary of the Pamba, the concentration of nutrients is even lower, because abundant water hyacinths absorb nutrients, hence to some extent serve as ‘sewage treatment plants’.
“Our study highlights the importance of collecting further data on a local scale that take into account different types of land use, especially in densely populated tropical river catchments,” stresses Tim Jennerjahn. “Only then global trends can be ascertained on the one hand and region-specific measures can be taken to sustain healthy waters on the other hand.”
David, S.E., Chattopadhyay, M., Chattopadhyay, S., Jennerjahn, T.C. (2015) Impact of human interventions on nutrient biogeochemistry in the Pamba River, Kerala, India. Science of The Total Environment 541, pp. 1420–1430.
Dr. Susanne Eickhoff | idw - Informationsdienst Wissenschaft
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences