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!
Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University
New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences