Emissions from land

As indicated above, national policies and international conventions have been invoked to curb known, and usually obvious, sources of marine pollution. National legislation is used to control coastal discharges of contaminants. A major problem remains owing to the inadequate treatment of sewage prior to emission from land-based sources. The most important deleterious effects in this case are with respect to microbial water quality. This can have a direct influence on bathing criteria and result in beach closures during contamination episodes. An additional problem from land-based sources pertains to transboundary effects, whereby pollution may inadvertently be exported from one country to another. 

Figure 5. Carbon footprint of different types of food products at retail. Average values estimated to be representative for food products sold on the Swedish market. Error bars show ranges of values found in the literature. Emissions from land use change and carbon stock changes in soils are not included [47]...

Searchinger, T., Heimlich, R., Houghton, R. A. et al. (2008). Use of US croplands for biofuels increases greenhouse gases through emissions from land-use change. Science Express, 319 (4th January), 1238-1240. 

Second, for several thousand years preceding 1850 (approximately the start of the industrial revolution), the concentration of CO2 varied by less than lOppmv (Etheridge et al., 1996) (Figure 2(b)). Since 1850, concentrations have increased by 85 ppmv (—30%). The timing of the increase is coincident with the annual emissions of carbon from combustion of fossil fuels and the net emissions from land-use change (Figure 3). 

In this discussion of heavy metals, geochemical cycles are treated in a simple manner emissions from land and oceans to the global atmosphere and subsequent deposition on the land and ocean surface, and runoff from the land to the ocean and eventual deposition in marine sediments. Only two components of this simple cycle will be discussed due to the availability of relatively accurate... 

Searchinger, T. Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change. Science 2008,319 (Feb 29), 1238-1248. 

Another important methodological aspect in the bioplastics life cycle relates to biogenic CO2 emission from land-use change. This is especially relevant when raw materials entering the bioplastics supply chain come from agricultural processes. 

For arable land, plus urea emissions from pasture. Based on total UK fertilizer consumption (Asman, 1992) ° and 0.68 agricultural land area as arable and ungrazed grass (MAFF, 1990). ... 

F or NjO, estimates of soil emissions are perhaps slightly more straightforward, simply because so much more information on soil NjO emissions is available. For agricultural soils, estimates as a percentage of fertilizer input have been published " and, for the remaining land use classes listed in Table 5, mean annual emissions from a series of long-term flux measurements are available. The total annual soil NjO emissions for the ElK (27 kt N) are very similar to the annual soil NO emissions. Soils, however, have by far a greater impact on the... 

Controlling methane release from wetland, rice paddies and gaseous emissions from animals is more problematic. The release from rice paddies and wet lands is slow, intermittent and takes place over a wide geographic area, and thus very difficult to control. Gaseous emissions from agricultural animals contribute to atmospheric accumulation of methane due to fermentative digestion that produces methane in... 

Houghton, R. A. (1993). Emissions of carbon from land-use change, paper presented at the 1993 Global Change Institute on the Carbon Cycle, Off. Interdisciplinary Earth Stud. Univ. Corp. Atmos. Res., Snowmass, Colorado, July 18-30. 

Being on-farm emissions (from cultivation and animals breeding) the most important source of GHG in food life cycle, numerous studies have tried to reduce them. Ahlgren [55] has used LCA to evaluate the use of biofuels in tractors and the substitution of mineral nitrogen fertilizers. This implied that 3-6% of a farm s available land was needed to produce the required biomass (to produce biofuels and fertilizer). 

Acid rain is caused primarily by sulfur dioxide emissions from burning fossil fuels such as coal, oil, and natural gas. Sulfur is an impurity in these fuels for example, coal typically contains 2-3% by weight sulfur.1M Other sources of sulfur include the industrial smelting of metal sulfide ores to produce the elemental metal and, in some parts of the world, volcanic eruptions. When fossils fuels are burned, sulfur is oxidized to sulfur dioxide (SO2) and trace amounts of sulfur trioxide (SC>3)J21 The release of sulfur dioxide and sulfur trioxide emissions to the atmosphere is the major source of acid rain. These gases combine with oxygen and water vapor to form a fine mist of sulfuric acid that settles on land, on vegetation, and in the ocean. 

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