Edited by Robert U. Ayres and Leslie W. Ayres
Chapter 33: Heavy metals in agrosystems
Simon W. Moolenaar* Agrosystems belong to the biosphere as well as the anthroposphere. They serve not only as signiﬁcant sources of energy and matter, but also as sinks for many residual ﬂuxes. Soils are vital constituents of agrosystems. Important functions include habitat protection for ﬂora and fauna, contribution to global nutrient cycling, the bearing function, the ﬁltering or buﬀer function, and others. Soil quality especially inﬂuences the quality of groundwater, which may serve as a resource for drinking water or as surface water recharge (de Haan 1996; Blum 1990; Harris et al 1996). One aspect of soil quality is the accumulation of heavy metals in soil. An analysis of the input and output ﬂuxes of Cd, Cu, Pb and Zn in agriculture and of their resulting accumulation in agricultural soils is necessary to ensure sustainable management of these metals in agricultural systems. Agrosystems may be viewed as ‘domesticated ecosystems’ intermediate between natural ecosystems (such as wild forest) and fabricated systems (for example, a city). Both agrosystems and natural ecosystems are solar-powered and are composed of primary producers, consumers and decomposers. Agrosystems diﬀer from natural systems in that they use manufactured products, including synthetic fertilizers, pesticides and hybrid seeds, as well as fossil fuels, while species diversity is greatly reduced by human management to optimize yields of desired products. The dominant plants and animals are under artiﬁcial rather than natural selection, and control is external to the system rather than via feedback and self-regulation as in...
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