Agriculture Reference
In-Depth Information
or urbanized may be drowned, causing the addition of nutrients,
particularly N and P, to coastal systems. Additionally, as sea levels
rise, wetland habitats are lost. Wetlands act as natural filters for
anthropogenic nutrients and are therefore important in regulating
nutrient loads to coastal waters. Wetlands and mangrove habitats
also provide a natural form of protection from storm surges and
flooding (Nicholls et al., 2007). Without these habitats, coastal wa-
ters may be more prone to increased levels of nutrients and nutrient
imbalance.
18.5 ENVIRONMENTAL CONTAMINANTS AND CHEMICAL
RESIDUES IN THE FOOD CHAIN
There are many pathways through which global climate change and vari-
ability mayimpact environmental contamination and chemical hazards in
foods. Contamination of agricultural and pastureland soil with dioxins
have been associated with climate change related extreme events, particu-
larly with the increased frequency of inland floods. Soil contamination can
be attributed to remobilization of contaminated river sediments, which are
subsequently deposited on the flooded areas. In other cases, contamination
of the river water bodies, and subsequently of the flooded soils, may have
resulted from mobilization in upstream-contaminated terrestrial areas such
as industrial sites, landfills, sewage treatment plants, etc. Results showed
very high levels of polychlorinated dibenzo-p-dioxins and dibenzofurans
(PCDD/Fs) present in soil in periodically flooded pastureland riverside of
the dikes, and grazing on the floodplains revealed a significant transfer of
PCDD/Fs into milk (Umlauf et al., 2005). While the uptake of contaminat-
ed soils during grazing is an important factor considering the transfer into
the food chain, barn feeding of properly harvested greens from the same
floodplains is less critical (Umlauf et al., 2005). Sources of chemical con-
tamination of flood water included oil spills from refineries and storage
tanks, pesticides, metals and hazardous waste. Several chemicals, such as
hexavalent chromium, manganese, p-cresol, toluene, phenol, 2, 4-D (an
herbicide), nickel, aluminum, copper, vanadium, zinc, andBenzidine were
detected in flood water. Trace levels of some organic acids, phenols, trace
cresols, metals, sulfur chemicals, and minerals associated with seawater
were also detected (EPA, 2005). Concentrations of most contaminants
