Environmental problems – An overview - Environmental Deterioration and Contamination: Problems and their Management - page 8

Figure 1.5 Comparisons of density, biomass, and productivity of the organisms of a simplified trophic
chain (from the bottom up: phototrophs, herbivori, carnivori, and predators).
trophic hierarchy are exposed to the largest concentrations of persistent and highly
bioaccumulative elements and compounds. The high concentrations due to bioaccu-
mulation and biomagnification may pose a very large risk in the case of hazardous
chemical substances.
A food chain is a linear sequence within a more complex food web. The scheme
in Figure 1.4 shows a simplified model of a community with four trophic levels. The
beginning of the food chain is always a primary producer, phototrophic plants or bacte-
ria, which can capture solar energy and convert it into chemical energy. The density of
individual organisms, their biomass, and productivity (the specific biomass production
per square meter and per day) are compared as shown in the prisms of Figure 1.5.
By considering productivity, we can observe the so-called 10% rule, which reflects
the fact that a large part of the energy moving up along the food chain is lost. Produc-
tivity or the incorporation of energy into the reduced organic matter building up the
body of living organism becomes less and less as we move along the food chain (the
100% in the phototrophs is only 10% in herbivores, 1% in carnivores, and 0.1% in
the predators).
By considering humans and the scarcity of food resources globally, we can under-
stand that vegetarians impact and load the ecosystem less than omnivores who eat
everything. This is the reason for the recommendation by many green organizations,
i.e., contribute to sustainability by becoming vegetarian, using slogans such as “healthy
people, healthy planet'' (EarthSave, 2011). It is true that methane is the main contrib-
utor to global warming and husbandry, mainly cattle farming, is largely responsible
for global methane production (see Table 1.1). General vegetarianism would largely
reduce cattle farming and, as a consequence, would result in better resource utilization
and less methane in our atmosphere. Methane is one of the main problems of our globe