That is what a study by the Universidad de Almería says, confirming for the first time that human excrements contribute to water pollution, primarily with nitrogen and phosphorus.
A team of researchers from the Universidad de Almería (UAL) has estimated the environmental impact of the Spanish diet and role that human excrements play in the life cycle of food. It is the first time that a scientific study of this type incorporates the role played by human excrements.
"Food in Spain produces emissions of around two tonnes of carbon dioxide per person and per year (more than 20% of total emissions per person and per year) and consumes 20 gigajoules of primary energy," main author of the study and researcher at the UAL Iván Muñoz told SINC.
The study, which was published recently in The International Journal of Life Cycle Assessment, analyses the relationship of the food production and consumption chain with global warming and the acidification and eutrophication (excess of nutrients) of the environment, taking what a person in Spain ate in 2005 (881 kilograms) as a reference.
Calculations included agricultural and animal production, industrial food processing, sale and distribution, preparation and cooking at home, solid waste treatment (food remains and packaging), as well as human excretion.
According to the study, producing food from animals, such as meat and dairy products, causes the greatest impact. Agriculture, livestock, fishing and the food industry are the greatest source of carbon dioxide water pollution, but in both cases the effects of human excretion (through breathing or due to waste water treatment) are next on the list.
Human Excretion Contributes Nutrients
"Human excretion contributes significantly to water polluting through providing organic matter and nutrients, such as nitrogen and phosphorus, which fosters the growth of algae, a decrease in the level of oxygen dissolved in the water, bad smells and other problems associated to eutrophication," Muñoz says, "although such effects are minimised by the purification processes performed before wastewaters are discharged into rivers or to the coast."
The researcher makes the point that returning these wastewaters to the environment is not a bad thing in itself, as they are nutrients, just like manure is reused as fertiliser in agriculture.
"The problem is that in many cases our rivers have a very low water level and find it difficult to soak up wastewaters, not only from excrements, but also from other sources such as pesticides and fertilisers used in farming and pollutants from industry," Muñoz indicates.
The researchers have also estimated the CO2 and methane produced by the human metabolism and the energy consumption associated to aspects such as using toilet paper, soap and basin water, together with the treatment of sewage at treatment stations.
As regards emissions, "human excrements have a net null effect on global warming, as they are offset by carbon fixation in photosynthesis. As a result, they do not contribute to increasing the concentration of CO2 in the atmosphere".
Ivan Muñoz, Llorenç Milà i Canals y Amadeo R. Fernández-Alba. "Life cycle assessment of the average Spanish diet including human excretion". The International Journal of Life Cycle Assessment 15(8): 794-805, 2010. DOI: 10.1007/s11367-010-0188-z
SINC | EurekAlert!
A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg
Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction