Trends in Phosphorus loads and concentrations, Baltic Sea, 1900-2030
The graphic shows trends in Phosphorus loads and concentrations in the Baltic Sea from 1900 to 1995 with projections to 2030. Phosphorus is an agricultural fertilizer. Phosphorus is produced in nature, but never in its pure form. As an agricultural fertilizer or from sewage released into water, it can cause excessive algae growth.
13 Feb 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Population density in the Baltic Sea drainage basin
The density of people per square kilometers have been calculated from various statistical sources, and displays the situation at approximately 1990. Population, and specifically cities, act as driving forces in regards to eutrophication on the Baltic Sea, primarily through nutrients (nitrogen, phosphorous) released through sewage plants.
04 Oct 2005 - by Hugo Ahlenius, UNEP/GRID-Arendal
Major cities in the Andean community
The urbanisation of the population has been happening since the first city, and is rapidly increasing in rate - especially since the dawn of industrialization. The Andean community consists out of five countries: Venezuela, Colombia, Ecuador, Peru and Bolivia - that are in the middle income class. The fast growing cities create new problems, like slums, sewage and the supply of resources.
20 Sep 2005 - by Hugo Ahlenius, UNEP/GRID-Arendal
Regional trends in biological oxygen demand
The graphic is a global comparison of the biological oxygen demand measured in milligrams per litre. It covers the years from 1976 - 2000. The biological oxygen demand refers to the amount of oxygen required by aerobic microorganisms to decompose the organic matter in a sample of water, such as that polluted by sewage.
28 Sep 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Ratio of wastewater treatment
Sewage treatment is low or absent in many parts of the World, leading to eutrophication of the coastal zone, (toxic) algae blooms and dramatically reduce the ability of coral to recover from bleaching events dramatically. The data reflects the bodies of the UNEP Regional Seas programme.
01 Nov 2008 - by Hugo Ahlenius, UNEP/GRID-Arendal
Urban water cycle
This graphic illustrates the impact of human activity on groundwater. It shows that groundwater is obtained from periurban wellfields and urban wells, then used and disposed of as wastewater through pluvial drainage, piped sewage and on-site sanitation and industrial effluent disposal. It also shows that wastewater is treated and then reused for irrigation, with excess flows re-entering the aquifers.
17 May 2005 - by Delphine Digout, UNEP/GRID-Arendal
Latvia, topographic map
Latvia is located in Eastern Europe, bordering the Baltic Sea, between Estonia and Lithuania, comprising of 64,589 sq km. It has a population of 2,290,237 (2005). Major environmental concerns are: Latvia's environment has benefited from a shift to service industries after the country regained independence; the main environmental priorities are improvement of drinking water quality and sewage system, household, and hazardous waste management, as w...
27 Sep 2005 - by Philippe Rekacewicz, Emmanuelle Bournay, UNEP/GRID-Arendal
Discharge of selected pollutants
Nitrogen and phosphorous represents nutrients that can be seen as pollutants, as large concentations of those increase eutrophication. Nutrients are present in primarily commercial fertilisers and in sewage. A measure of eutrophication is biochemical oxygen demand (BOD), which measures the activity in the water column. High BOD means that there is low water quality (in terms of eutrophication) and high activity of bacteria in the water. This grap...
29 Nov 2007 - by Philippe Rekacewicz, UNEP/GRID-Arendal
Caribbean casualties due to hurricanes
From Trinidad to Tallahassee, Florida, tropical storms have ravaged the Caribbean basin, exacting a multibillion-dollar toll on housing, schools, hospitals, roads and sewage systems. Most of the casualties were in Haiti. But almost no community escaped unscathed. In Grenada, half of the population is now homeless, the famed nutmeg groves flattened, the power plants wrecked. The tourism industry that was the island’s lifeblood could take years to ...
01 Feb 2006 - by Emmanuelle Bournay, UNEP/GRID-Arendal
Centralized or decentralized? - Uganda. A study case
Looking at the costs and benefits, centralized systems may not be the answer in terms of best result for the investment. The chart on the left shows that the financial NPV does not change with increasing population size for centralized sewage and wastewater connection, however the economic NPV (which includes benefits to health and the environment) shows a positive trend with increas- ing populations. Centralized systems therefore generate a grea...
01 Mar 2010 - by UNEP/GRID-Arendal
Industrial areas and seasonal zones of oxygen depleted waters
This graphic illustrates the strong link between areas with high densities of industrial activity and zones of seasonally oxygen-depleted waters.
There is a strong link between areas with high densities of industrial activity and zones of seasonal oxygen-depleted waters. In recent years there has been an increasing focus on treating and reducing municipal and industrial waste, and on reducing nitrogen levels in agricultural runoff. However, less...
26 Jan 2009 - by Phillipe Rekacewicz, (Le Monde diplomatique) February 2008
Access to sanitation in Yaoundè
Proper disposal of sewage is essential for urban water quality, and in Yaoundè the treatment of wastewater, excreta, and sewage can be classified into two categories – individual wastewater systems (septic tanks and latrines) and collective wastewater systems (sewer and treatment plants). About half of the residents of Yaoundè are connected to the sewer system, while the rest depend on either septic tanks, latrines, or a combination of the two.
18 Mar 2011 - by Riccardo Pravettoni, UNEP/GRID-Arendal