Agriculture Reference
In-Depth Information
for irrigation provided certain precautions are taken (Abbot and Hasnip,
1997). Such water is polluted as a consequence of mixing with wastewater
or agricultural drainage (Cornish et al, 1999).
Indirect use of wastewater: This is the unplanned application to land of
wastewater from a receiving water body. Municipal and industrial
wastewater is discharged without treatment or monitoring into the
watercourses draining an urban area. Irrigation water is drawn from rivers
and streams or other natural water bodies that receive wastewater flows.
There is often no control over the use of water for irrigation or domestic
consumption downstream of the urban centre. Consequently, many farmers
indirectly use marginal-quality water of unknown composition that they
draw from many points downstream of the urban centre.
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Research objectives
This chapter has four primary objectives:
1 To assess the water quality (biological and chemical) of irrigation water
sources used for vegetable cultivation.
2 To trace the (microbiological and helminth) contamination pathways of
vegetables in urban and peri-urban sites to identify where interventions
should take place along the production-consumption continuum.
3 To isolate and identify fecal coliform (FC) bacteria found on irrigated
vegetables from urban and peri-urban sites.
4 To determine the level of pathogen and pesticide contamination of vegetables
produced on urban agricultural sites.
Hypotheses
Three basic hypotheses underlie this research:
1 Fecal coliform (FC) and helminth egg population levels in wastewater from
different urban sources exceed common standards recommended for irrigation.
2 Microbiological (FC and helminth levels) contamination of wastewater-
irrigated vegetables is increased through handling and distribution within
the production marketing chain.
3 Potential health risks to consumers are not reduced to acceptable levels after
the normal household treatment of vegetables.
M
ETHODS
Phases of research and cities studied
The study was divided into three phases. The first phase (market sampling)
was conducted in the three Ghanaian cities of Accra, Kumasi and Tamale
(Figure 6.1). The second phase (water to field to market sampling) took place
